FOCAL COMMUNICATIONS CORP
10-Q, 1999-05-07
RADIOTELEPHONE COMMUNICATIONS
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<PAGE>
 
     As filed with the Securities and Exchange Commission on May 7, 1999 

   
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549


                                   FORM 10-Q


  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
                                  ACT OF 1934

                 For the Quarterly Period Ended March 31, 1999

                            Commission file number
                                   333-49397

                       Focal Communications Corporation
            (Exact name of registrant as specified in its charter)

                                        
                                   Delaware
                           (State of incorporation)
                                        
                                  36-4167094
                     (IRS Employer Identification Number)
                                        

                             200 N. LaSalle Street
                                  Suite 1100
                               Chicago, IL 60601
                   (Address of principal executive offices)

                                (312) 895-8400
                        (Registrant's telephone number)


     Indicate by check mark whether the registrant (1) has filed all reports 
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days:

                                Yes   X      No 
                                    -----  -----

     The number of shares outstanding of the issuer's common stock, as of May 1,
1999:

                 Common stock ($.01 par value)  97,764 shares

<PAGE>
 
                                     INDEX

<TABLE> 
<CAPTION> 
                                                                                                               Page
                                                                                                               ----

<S>              <C>                                                                                           <C> 
PART I--FINANCIAL INFORMATION                                                                                    -

Item 1.          Financial Statements (Unaudited)

                 Consolidated Statements of Operations -- Three months ended March 31, 1999 and 1998......       3

                 Consolidated Balance Sheets -- March 31, 1999 and December 31, 1998......................       4

                 Consolidated Statements of Cash Flows -- Three months ended March 31, 1999 and 1998......       5

                 Condensed Notes to Unaudited Interim Consolidated Financial Statements...................       6

Item 2.          Management's Discussion and Analysis of Financial Condition and Results of Operations....      11

Item 3.          Quantitative and Qualitative Disclosures About Market Risk...............................      15


PART II--OTHER INFORMATION

Item 1.          Legal Proceedings........................................................................      16

Item 2.          Changes in Securities and Use of Proceeds................................................      17  

Item 4.          Submission of Matters to a Vote of Security Holders......................................      17  

Item 6.          Exhibits and Reports on Form 8-K.........................................................      18

SIGNATURES................................................................................................      22
</TABLE> 
<PAGE>
 
                         Part I--Financial Information

Item 1. Financial Statements


               FOCAL COMMUNICATIONS CORPORATION AND SUBSIDIARIES

                     CONSOLIDATED STATEMENTS OF OPERATIONS

<TABLE>
<CAPTION>
                                                                                   For the three months
                                                                                   --------------------
                                                                                      ended March 31,
                                                                                      ---------------
                                                                                 1999               1998
                                                                              -----------        -----------
<S>                                                                           <C>                <C>
REVENUES.........................................................             $26,003,897        $ 5,102,448

EXPENSES:

   Customer service and network operations.......................              10,369,319          1,826,893

   Selling, general and administrative...........................               5,665,896          1,307,625

   Depreciation and amortization.................................               4,026,750            890,871

   Non-cash compensation expense.................................                 397,410            325,000
                                                                              -----------        -----------
       Total operating expenses..................................              20,459,375          4,350,389
                                                                              -----------        -----------
       Operating Income..........................................               5,544,522            752,059
                                                                              -----------        -----------
OTHER INCOME (EXPENSE):

   Interest income...............................................               1,306,082          1,015,902

   Interest expense..............................................              (5,403,584)        (2,109,152)
                                                                              -----------        -----------
   Total Other Expense...........................................              (4,097,502)        (1,093,250)

NET INCOME(LOSS).................................................             $ 1,447,020        $  (341,191)
                                                                              ===========        ===========
</TABLE> 
<PAGE>

<TABLE>
<CAPTION>
<S>                                                                              <C>                <C>
BASIC NET INCOME (LOSS) PER SHARE
  OF COMMON STOCK....................................................            $  16.46           $  (3.86)
                                                                                 ========           ========

DILUTED NET INCOME (LOSS) PER SHARE
  OF COMMON STOCK....................................................            $  14.44           $  (3.86)
                                                                                 ========           ========

BASIC WEIGHTED AVERAGE NUMBER OF SHARES
  OF COMMON STOCK OUTSTANDING........................................              87,922             88,307
                                                                                 ========           ========

DILUTED WEIGHTED AVERAGE NUMBER OF SHARES
  OF COMMON STOCK OUTSTANDING........................................             100,208             88,307
                                                                                 ========           ========
</TABLE>
<PAGE>
 
               FOCAL COMMUNICATIONS CORPORATION AND SUBSIDIARIES

                          CONSOLIDATED BALANCE SHEETS

                     March 31, 1999 and December 31, 1998

<TABLE>
<CAPTION>
                                                                                March 31, 1999     December 31, 1998
                                                                                --------------     -----------------
<S>                                                                             <C>                <C>
ASSETS
- ------

CURRENT ASSETS:

   Cash and cash equivalents................................................       $106,598,881        $126,041,001

   Short-term investments...................................................          7,460,850           7,959,940

   Accounts receivable, trade (net of allowance for doubtful accounts of
     $1,960,000 and $1,189,000 at March 31, 1999 and
     December 31, 1998, respectively).......................................         15,975,803           9,792,532
   Other current assets.....................................................          1,149,104             843,793
                                                                                   ------------        ------------
       Total current assets.................................................        131,184,638         144,637,266

FIXED ASSETS, at cost:......................................................        100,595,860          76,119,650
   Less--Accumulated depreciation and Amortization  ........................          9,872,098           6,146,530
                                                                                   ------------        ------------
       Fixed assets, net....................................................         90,723,762          69,973,120

   Other Non-Current Assets (net)...........................................          4,662,711           4,963,894

                                                                                   $226,571,111        $219,574,280
                                                                                   ============        ============


                                                                                March 31, 1999     December 31, 1998
                                                                                --------------     -----------------
LIABILITY AND STOCKHOLDERS' EQUITY
- ----------------------------------


CURRENT LIABILITIES:
</TABLE> 
<PAGE>

<TABLE>
<CAPTION>
<S>                                                                              <C>                <C>
  Accounts payable.......................................................          $  5,152,815        $  8,365,470

  Accrued liabilities....................................................             2,513,581           1,941,377

  Income taxes payable...................................................                    --           4,055,000

  Current maturities of long-term debt...................................             4,108,935           2,887,036
                                                                                   ------------        ------------
     Total current liabilities...........................................            11,775,331          17,248,883

LONG-TERM DEBT, net of current maturities................................           191,436,957         182,408,757
                                                                                   ------------        ------------

OTHER NONCURRENT LIABILITIES.............................................             1,644,128             588,228
                                                                                   ------------        ------------

STOCKHOLDERS' EQUITY:
  Common Stock, Class A, $.01 par value, 100,000 shares authorized,
    75,746 and 75,374 issued and outstanding at March 31, 1999 and
    December 31, 1998....................................................                   757                 753


  Common Stock, Class B, $.01 par value; 35,000 shares authorized,
    22,000 shares issued at March 31, 1999 and December 31, 1998.........                   220                 220
  Additional paid-in capital  ...........................................            35,955,194          35,413,345

  Deferred compensation  ................................................            (4,339,022)         (4,736,432)

  Accumulated deficit  ..................................................            (9,902,454)        (11,349,474)
                                                                                   ------------        ------------
     Total stockholders' equity   .......................................            21,714,695          19,328,412
                                                                                   ------------        ------------
                                                                                   $226,571,111        $219,574,280
                                                                                   ============        ============
</TABLE>
<PAGE>
 
               FOCAL COMMUNICATIONS CORPORATION AND SUBSIDIARIES

                     CONSOLIDATED STATEMENTS OF CASH FLOWS

<TABLE>
<CAPTION>
                                                                              For three  months ended
                                                                           -----------------------------
                                                                                     March 31,
                                                                           -----------------------------
                                                                               1999              1998
                                                                           ------------      -----------
<S>                                                                        <C>                <C>
Cash Flows From Operating Activities:

Net Income (loss)........................................................  $  1,447,020      $  (341,191)

Adjustments to reconcile net income (loss) to net cash
  provided by (used in) operating activities-
     Depreciation and amortization.......................................     4,026,750          890,871

     Deferred lease costs................................................       389,234           89,741

     Deferred compensation...............................................       397,410          325,000

     Amortization of discount on Senior Discount Notes...................     4,952,327        2,062,174

     Provision for losses on accounts receivable.........................     1,145,000          577,000

     Changes in operating assets and liabilities-

        Accounts receivable..............................................    (7,328,271)      (3,418,065)

        Related-party receivables........................................            --          (85,466)

        Other current assets.............................................      (305,311)        (238,072)
        Accounts payable and accrued liabilities.........................    (2,640,451)       3,883,263

        Income taxes payable.............................................    (4,055,000)              --

        Other non-curent liabilities.....................................       666,666               --
                                                                           ------------     ------------

           Net cash provided by(used in) operating activities............    (1,304,626)       3,745,255
                                                                           ------------     ------------
Cash Flows From Investing Activities:

     Capital expenditures................................................   (24,476,209)      (7,593,061)

     Change in short-term investments....................................       499,090               --
                                                                           ------------      -----------
           Net cash used in investing activities.........................   (23,977,119)      (7,593,061)
                                                                           ------------      -----------
Cash Flow From Financing Activities:
</TABLE>
<PAGE>

<TABLE>
<S>                                                                        <C>                <C>
     Proceeds from issuance of long-term debt............................     5,807,191      144,083,351

     Payments on long-term debt..........................................      (509,419)      (3,533,153)

     Proceeds from the issuance of Class A Common Stock..................       541,853       13,800,000
                                                                           ------------     ------------

           Net cash provided by financing activities.....................     5,839,625      154,350,198
                                                                           ------------     ------------

Net Increase (Decrease) In Cash And Cash Equivalents.....................   (19,442,120)     150,502,392

Cash and Cash Equivalents, beginning of period...........................   126,041,001        2,256,552
                                                                           ------------     ------------

Cash and Cash Equivalents, end of period.................................  $106,598,881     $152,758,944
                                                                           ============     ============
</TABLE>
<PAGE>
 
               FOCAL COMMUNICATIONS CORPORATION AND SUBSIDIARIES

    CONDENSED NOTES TO UNAUDITED INTERIM CONSOLIDATED FINANCIAL STATEMENTS

                       Three months ended March 31, 1999

1.   Basis of Presentation

  The accompanying unaudited interim consolidated financial statements reflect
all adjustments, consisting of normal recurring accruals, which management
believes are necessary to present fairly the financial position, results of
operations, and cash flows for Focal Communications Corporation and Subsidiaries
(the "Company") for the respective periods presented. Certain information and
footnote disclosures normally included in the annual financial statements
prepared in accordance with generally accepted accounting principles have been
condensed or omitted pursuant to the rules and regulations of the Securities and
Exchange Commission for Form 10-Q. These unaudited interim consolidated
financial statements should be read in conjunction with the Company's Annual
Report on Form 10-K for the year ended December 31, 1998, filed on March 31,
1999, as amended by Form 10-K/A filed on April 7, 1999. The consolidated balance
sheet at December 31, 1998 included herein was derived from the Company's
audited consolidated financial statements, but does not include all disclosures
required under generally accepted accounting principles.

2.  Risks and Uncertainties

     Reciprocal compensation payments are amounts paid by one carrier to send 
particular traffic to another carrier's network. Reciprocal compensation is 
currently a significant component of the Company's total revenues representing 
approximately 73% and 77% of our total revenues for the three month periods 
ended March 31, 1999 and 1998, respectively.

     One carrier is disputing its obligation to pay some of the reciprocal
compensation owed to the Company. Although this dispute was ruled on in favor of
the Company by the Illinois Commerce Commission in March 1998 and by a federal
court in July 1998, it is currently subject to appeal. Substantially all of the
disputed amounts have been collected. There is a risk that prior decisions and
any future appeal regarding the settlement of this dispute in favor of the
Company could be revisited, which could allow the carrier to obtain a refund of
prior reciprocal compensation payments.

     As a result of several trends in our business and the current regulatory 
environment, the Company expects revenues from reciprocal compensation to
decline significantly. A reduction in or elimination of revenues attributable to
reciprocal compensation which is not offset by increases in other revenues
generated by the Company may have a material adverse effect on the Company.

3.   Property and Equipment

  Property and equipment consist of the following:

<TABLE>
<CAPTION>
                                       March 31,          December 31,
                                   ------------------  ------------------
                                          1999                1998
                                   ------------------  ------------------
<S>                                <C>                 <C>
      Buildings and improvements      $  2,350,000         $ 2,350,000
      Communications Network            57,015,325          44,774,965
      Construction in progress          23,496,685          15,103,564
      Computer Equipment                 4,550,282           3,503,512
      Leasehold Improvements            11,089,518           8,577,724
</TABLE> 
<PAGE>
<TABLE> 
<S>                                    <C>                  <C>  
      Furniture and fixtures.........     2,041,502           1,790,596
      Motor vehicles.................        52,548              19,289
                                       ------------         -----------
                                        100,595,860          76,119,650
      Less--Accumulated Depreciation
       and Amortization..............     9,872,098           6,146,530
                                       ------------         -----------
                                       $ 90,723,762         $69,973,120
                                       ============         ===========
</TABLE>

4.   Debt

  Long-term debt consists of the following:

<TABLE>
<CAPTION>
                                                                          March 31,      December 31,
                                                                       ---------------  --------------
                                                                            1999             1998
                                                                       ---------------  --------------
<S>                                                                    <C>              <C>
      12.125% senior discount notes due 2008, net of
        unamortized Discount of $98,944,689 and $103,897,016
         at March 31, 1999 and December 31, 1998, respectively.......     $171,055,311    $166,102,984

      Secured equipment term loan, maximum borrowing level at........       24,490,581      19,192,809
       $25,000,000...................................................  ---------------    ------------
                                                                           195,545,892     185,295,793
      Less--current maturities.......................................        4,108,935       2,887,036
                                                                          ------------    ------------
                                                                          $191,436,957    $182,408,757
                                                                          ============    ============
</TABLE>

In December, 1998, the Company obtained a secured equipment term loan (the
"Facility") from a third party with a maximum borrowing level of $25,000,000.
The Facility provides for, among other things, equipment drawdowns through
December 30, 1999, and requires repayment based on 60 equal monthly installments
of principal and interest for each drawdown. All drawdowns under the Facility
bear interest at the five-year swap rate percent plus additional basis points,
as defined in the Facility. Total drawdowns of $24,490,581 and $19,192,809 were
outstanding under the Facility as of March 31, 1999 and December 31, 1998,
respectively. The Facility provides for certain restrictive financial and
nonfinancial covenants. Among other things, these covenants require the
<PAGE>

maintenance of minimum cash flow and revenue levels. The Company was in
compliance with these covenants as of December 31, 1998 and March 31, 1999.

In April 1999, the Company amended the Facility to provide a maximum borrowing
level of $50 million.

5.   Earnings Per Share

  In February 1997, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards (SFAS) No. 128 ''Earnings Per Share''. SFAS No.
128 changed the methodology of calculating earnings per share and renamed the
two calculations to basic earnings per share and diluted earnings per share. 
Basic earnings per common share are based on the average quarterly weighted
average number of shares of common stock outstanding. This calculation includes
all Class A shares and the vested portion of the Class B shares. Diluted
earnings per common share are adjusted for the assumed exercise of dilutive
stock options and unvested class B Common shares. Since the adjustments required
for the calculation of diluted weighted average common shares outstanding are
anti-dilutive, this calculation has been excluded from the loss per share
calculation for the first quarter of 1998. Under the requirements of SFAS No.
128 the Company's basic and diluted weighted average number of shares
outstanding at March 31, 1999 and 1998 is as follows:

<TABLE>
<CAPTION>
                                                  March 31,     March 31,
                                                 ------------  ------------
                                                     1999          1998
                                                 ------------  ------------
<S>                                              <C>           <C>
       Basic Weighted Average Number of Common
        Shares Outstanding......................     87,922        88,307
       Dilutive Stock Options and unvested
        Class B common stock....................     12,286        13,304
                                                    -------       -------
      Dilutive Weighted Average Number of
        Common Shares Outstanding...............    100,208       101,611
                                                    =======       =======
</TABLE>

  Diluted weighted average common shares outstanding are anti-dilutive and have
been excluded from the loss per share calculation for the first quarter of 1998.

6.   Commitments and Contingencies

  Under the terms of various short and long-term contracts, the Company is
obligated to pay office rents and rent for leasing fiber optic transmission
facilities. The Company is obligated to pay office rents through 2012. The
office rent contracts provide for certain scheduled increases and for possible
escalation of basic rentals based on a change in the cost of living or on other
factors. The Company expects to enter into other contracts for additional office
space, other facilities, equipment and maintenance services in the future.

  A summary of such fixed commitments at March 31, 1999 is as follows:

<TABLE>
<CAPTION>
                          Year                           Amount
                          ----                           ------       
                          <S>                            <C>
                          1999                         $4,110,359
                          2000                          5,820,645
</TABLE> 
<PAGE>

<TABLE>
<CAPTION>
                     <S>             <C>      <C> 
                     2001            .          5,677,135
                     2002            .          5,795,391
                     2003            .          5,876,725
                     Thereafter      .         29,440,140
                                              -----------
                                              $56,720,395
                                              ===========
</TABLE>
     On March 25, 1999, the Company amended its product purchase agreement with
a vendor, which provides for, among other things, a minimum commitment to
purchase $25 million in communications network equipment every 12 months, or an
aggregate over the term of the agreement of $75 million, at pre-established
prices.

     In April and May of 1999, the Company entered into two agreements for the
rights of use for fiber transport capacity with a combined total minimum
commitment of $87.9 million (Note 9).

7.   Stock Options

     The Company has chosen to account for stock based compensation using the
intrinsic value method prescribed in Accounting Principals Board Opinion
("APB") No. 25, "Accounting for Stock Issued To Employees." Accordingly, no
compensation expense has been recorded for its stock option awards, but rather,
the Company has determined the pro forma net loss amount for the first quarter
of 1999 as if compensation expense had been recorded for options granted during
1998 and the first quarter of 1999 under the fair value method described in SFAS
No. 123, "Accounting for Stock-Based Compensation."

     The Company utilizes the Black-Scholes option pricing model to estimate the
fair value of options at the date of grant. Had the Company adopted SFAS No.
123, pro forma net income applicable to common stockholders and pro forma basic
and diluted net income per share of common stock would have been approximately
$936,000 and $10.65 and $9.34, respectively, for the quarter ended March 31,
1999.

     The Black-Scholes option model estimated the weighted average fair value at
the date of grant of options granted for the three months ended March 31, 1999 
to be approximately $1,113 per option. Principal assumptions used in applying 
the Black-Scholes model were as follows:

<TABLE>
<CAPTION>

                                               For the
                                             Three Months
                                                Ended
                                               March 31,
                                                 1999
                                             ------------
<S>                                          <C>
Risk-free interest rates...................       4.57%
Expected life..............................    5 years
Expected volatility........................      87.29%
Expected dividend yield....................         --
                                               =======
</TABLE>

     The following summarizes option activity:

<TABLE>
<CAPTION>
                                                                                               Weighted
                                                                    Shares of                   Average
                                                                     Class A      Exercise     Exercise
                                                                      Common       Prices        Price
                                                                    ---------   ------------   ---------
<S>                                                                 <C>         <C>            <C>
         Outstanding at December 31, 1998........................     7,190     $ 290-$1,500      $1,090
         Activity for the three months ended March 31, 1999:
            Options Granted......................................     1,034     $      1,575   $   1,575
            Options Exercised....................................       (72)       290-1,500         962
            Options Canceled....................................       (30)     1,500-1,575       1,530
                                                                      -----     ------------   ---------
         Outstanding at March 31, 1999...........................     8,122     $  290-1,575   $   1,165
                                                                      =====     ============   =========
</TABLE>
               FOCAL COMMUNICATIONS CORPORATION AND SUBSIDIARIES

     The following table summarizes information about fixed stock options 
outstanding at March 31, 1999:

<TABLE>
<CAPTION>

                                            Options Outstanding                  Options Exercisable
                                  ----------------------------------------     ------------------------
                                                   Weighted
                                                    Average       Weighted                     Weighted
                                                   Remaining       Average                     Average
                                    Options       Contractual     Exercise       Options       Exercise
Range of Exercise Prices          Outstanding        Life           Price      Exercisable      Price
- ------------------------          -----------     -----------     --------     -----------     --------
<S>                               <C>             <C>             <C>          <C>             <C>
$290-$335                            1,767            8.3          $  311           596         $  307
$1,050-$1,575                        6,355            9.4           1,384           494          1,504
                                     -----            ---          ------         -----         ------
At March 31, 1999                    8,122            9.4          $1,165         1,090         $  850
                                     =====            ===          ======         =====         ======
</TABLE>

8.   SEGMENT INFORMATION

     In 1998, the Company adopted SFAS No. 131, "Disclosures about Segments of 
an Enterprise and Related Information." The Company is organized primarily on 
the basis of strategic geographic operating segments that provide communications
services in each respective geographic region. All of the Company's geographic 
operating segments have been aggregated into one reportable segment,
"Communications Services," as of and for the three months ended March 31, 1999
and 1998.

     The Company's chief operating decision maker views earnings before 
interest, taxes, depreciation and amortization ("EBITDA") as the primary measure
of profit and loss. The following represents information about revenues and 
EBITDA (which excludes non-cash compensation), total assets and capital 
expenditures for the Communications Services reportable segment as of and for 
the year ended December 31, 1998, and the three months ended March 31, 1999 and
1998:


<TABLE>
<CAPTION>
                                                 March 31,     December 31,
                                                   1999            1998
                                                -----------    ------------
    <S>                                        <C>             <C>
     Revenues.................................  $26,003,897    $43,531,846
     EBITDA...................................   10,000,062     15,161,031
     Total assets.............................   94,287,205     73,436,768
     Capital expenditures.....................   24,476,209     64,229,247
                                                ===========    ===========
</TABLE>

     The following reconciles total segment EBITDA to consolidated net income
(loss) before income taxes for the three months ended March 31, 1999 and 1998:

<TABLE>
<CAPTION>                                       Three months    Three months
                                                   ended           ended
                                               March 31, 1999  March 31, 1998
                                               --------------  --------------
    <S>                                      <C>             <C>
     Total EBITDA for reportable segment......  $10,000,062      $ 1,851,736
     Corporate EBITDA.........................      (31,380)         116,194
     Depreciation and amortization............   (4,026,750)        (890,871)
     Interest expense.........................   (5,403,584)      (2,109,152)
     Interest income..........................    1,306,082        1,015,902
     Non-cash compensation....................     (397,410)        (325,000)
                                                -----------      -----------
       Net income (loss) before income taxes..  $ 1,447,020      $  (341,191)
                                                ===========      ===========
</TABLE>

     The following reconciles segment total assets to consolidated total assets 
as of March 31, 1999 and 1998:

<TABLE> 
<CAPTION> 
                                                 March 31,       December 31,
                                                   1999              1998
                                                -----------      ------------
     <S>                                        <C>            <C> 
     Total assets for reportable segment......  $ 94,287,205     $ 73,436,768
     Cash, cash equivalents and short-term
       investments............................   114,059,731      133,307,515
     Other current assets.....................       199,235        1,125,124
     Fixed assets, net........................    13,362,229        6,740,979
     Other noncurrent assets..................     4,662,711        4,963,894
                                                ------------     ------------  
       Total consolidated assets..............  $226,571,111     $219,574,280
                                                ============     ============
</TABLE> 

     The Company currently only operates in the United States. Revenues by major
customer for the three months ended March 31, 1999 and 1998, are as follows:

<TABLE> 
<CAPTION>                                       Three months    Three months
                                                   ended           ended
                                               March 31, 1999  March 31, 1998
                                               --------------  --------------
    <S>                                       <C>             <C> 
     Revenues from major customer A...........  $13,265,330      $  3,694,508
     Revenues from major customer B...........  $ 5,761,531      $     --
                                                ============     ============
</TABLE> 

<PAGE>
 
         CONDENSED NOTES TO UNAUDITED INTERIM CONSOLIDATED FINANCIAL 
                            STATEMENTS--(Continued)
                                        
9.   Subsequent Events

     On April 15, 1999, the Company amended the Facility to increase the maximum
borrowing level from $25 million to $50 million.

     On April 28, 1999, the Company signed an agreement for the acquisition of
indefeasible rights of use for fiber transport capacity for a minimum of 8,300
fiber miles. The term of the agreement is 20 years and the total minimum
commitment is approximately $17.9 million. The agreement requires an initial
payment of approximately $3.6 million in the second quarter of 1999.

     On May 4, 1999, the Company signed an agreement with another carrier for
the lease of fiber transport capacity for a five year term and a minimum
commitment of $70 million. The Company has committed to $10 million in year one;
$13.2 million in year 2; and $15.6 million for each of the remaining three years
of the agreement.

<PAGE>
 
Item 2.   Management's Discussion and Analysis of Financial Condition and
          Results of Operations

Overview
 
     General.  We provide data, voice and colocation services to large,
communications-intensive users in major cities. We began operations in 1996 and
initiated service first in Chicago in May 1997. We currently serve a total of
12 markets, which encompass a total of 31 metropolitan statistical areas, or
MSAs, and plan to serve 16 markets, or 42 MSAs, by the end of 1999 and 20
markets, or 50 MSAs, by the end of 2000. We believe our market expansion will
allow us to reach a critical mass of geographic coverage and service capability
for our target customer base of communications-intensive users. As of March 31, 
1999, we had sold 85,329 access lines, of which 70,572 were installed and in
service.
 
     Our operating results are expected to change over the next 15 months as a
result of several trends in our business and in the regulatory environment.
First, we anticipate that the mix of lines we sell will shift from being
dominated by ISP customer lines to being more evenly balanced among ISP,
corporate and VAR customer lines due to expanded marketing efforts. Second, we
expect our revenue from and margin on ISP lines to decline as our
interconnection agreements in each state in which we operate come up for
renewal. In response to these trends, we intend to emphasize the sale of new
products that leverage our network to maximize revenues per line and operating
margins. These products include high-speed access to the Internet and LANs using
DSL technology. Third, our continued expansion may result in negative operating
cash flow and operating losses for a period of time. If this occurs, we expect
to again produce positive operating cash flows once these trends stabilize and
operating activities in our newer markets are established and mature. If,
however, these trends do not stabilize or our operating activities are not
established or do not mature as expected, we may continue to sustain negative
operating cash flow and net losses.
 
     Revenue.  Our revenue is comprised of monthly recurring charges, usage
charges and initial, non-recurring charges. Monthly recurring charges include
the fees paid by our customers for lines in service, additional features on
those lines, and colocation space. Monthly recurring charges are derived only
from end user customers. Usage charges consist of fees paid by end users for
each call made, fees paid by the ILEC and other CLECs as reciprocal
compensation, and access charges paid by the IXCs for long distance traffic
that we originate and terminate. Non-recurring revenues are typically derived
from fees charged to install new customer lines.
 
     We earn reciprocal compensation revenue for calls made by customers of
another local exchange carrier to our customers. Conversely, we incur
reciprocal compensation expense to other local exchange carriers for calls by
our customers to their customers. Reciprocal compensation has historically been
a significant component of our total revenue due to the preponderance of
inbound applications utilized by our customers. Reciprocal compensation
represented approximately 73% and 77% of total revenues for the three months 
ended March 31, 1999 and 1998, respectively.
 
     We expect the proportion of revenues represented by reciprocal compensation
to substantially decrease in the future as a result of the expiration and
subsequent renegotiation of our existing interconnection agreements with the
ILECs and as a result of our focus on increasing the percentage of our lines
that are sold to non-ISP customers. We expect the most significant impact of
the reduction in reciprocal compensation to occur when our existing
interconnection agreement with Ameritech Illinois, which expires during the
fourth quarter of 1999, is renegotiated. Although we expect to renew our
existing interconnection agreements on satisfactory terms, we expect that the
new agreements will result in lower negotiated interconnection rates for future
reciprocal compensation. Revenues from reciprocal compensation could also
decline as a result of adverse judicial or regulatory determinations.

<PAGE>
 
     Operating Expenses.  Our operating expenses are categorized as customer
service and network operations, selling, general and administrative,
depreciation and amortization, and non-cash compensation expense. Settlement
costs are a significant portion of customer service and network operations
expense and are comprised of leased transport charges and reciprocal
compensation payments. Leased transport charges are the lease payments we make
for the use of fiber transport facilities connecting our customers to our
switches and for our connection to the ILECs' and other CLECs' networks. Our
strategy of initially leasing rather than building our own fiber transport
facilities has resulted in our cost of service being a significant component of
total costs. To date, we have been successful in negotiating lease agreements
that match the duration of our customer contracts, thereby allowing us to avoid
the risk of incurring expenses associated with transport facilities that are
not being used by revenue generating customers.
 
     Historically leasing rather than building our transport network has
resulted in capital expenditures which we believe are lower than those of CLECs
of similar size that own their fiber networks. Our capital expenditures have
been driven by customer service demands and projected near-term revenue streams
from our established markets. In addition, we believe that the percentage of
these "success-based" capital expenditures is higher than those of fiber-based
CLECs. In contrast, we incur operating expenses for leased facilities that are
proportionately higher than those incurred by fiber-based CLECs. The margin
impact of these higher, anticipated operating expenses is expected to be
mitigated, in part, by a higher revenue per line, which we anticipate as a
result of our focus on communications-intensive users. In April and May of 1999,
we entered into a number of agreements to use fiber transport facilities for a
combined minimum commitment of $87.9 million over five years. See Note 9 to
Unaudited Interim Consolidated Financial Statements. These commitments will
result in increased operating expenses for future periods, which we believe
should be more than offset by future revenues associated with new services made
possible, in part, by these agreements.

     Our business plan contemplates selected purchases of our own local fiber
transport capacity to support our customer network and service demands. We
expect that our purchase of local fiber transport capacity as part of
developing our hybrid network will partially mitigate the increase in 
transport expense previously discussed.
 
     Other customer service and network operations expense consists of the costs
of operating our network and the costs of providing customer care activities.
Major components include wages, rent, power, equipment maintenance, supplies
and contract employees.
 
     Selling, general and administrative expense consists of sales force
compensation and promotional expenses as well as the cost of corporate
activities related to regulatory, finance, human resources, legal, executive,
and other administrative activities. We expect our selling, general and
administrative expense to be lower as a percentage of revenue than that of our
competitors because we have relatively high sales productivity associated with
our strategy of serving communications-intensive customers. These customers
generally utilize a large number of switched access lines relative to the
average business customer, resulting in more revenue per sale. Further, fewer
sales representatives are required to service the relatively smaller number of
communications-intensive customers in a given region.
 
     We record monthly non-cash compensation expense related to shares issued to
some of our executive officers in November 1996, and in connection with the
September 30, 1998 amendments to vesting agreements with some of our executive
officers. We will continue to record non-cash compensation expense in future
periods relating to these events through the third quarter of 2002.


Quarterly Results
 
     The following table sets forth unaudited financial, operating and
statistical data for each of the specified quarters of 1998 and 1999. The
unaudited quarterly financial information has been prepared on the same basis
as our Consolidated Financial Statements and, in our opinion, contains all
normal recurring adjustments necessary to fairly state this information. The
operating results for any quarter are not necessarily indicative of results for
any future period.
 

<PAGE>
 
<TABLE>
<CAPTION>
                                              1998                             1999
                          ------------------------------------------------  -----------
                            First       Second       Third       Fourth        First
                           Quarter     Quarter      Quarter      Quarter      Quarter
                          ----------  ----------  -----------  -----------  -----------
<S>                       <C>         <C>         <C>          <C>          <C>
Revenues................  $5,102,448  $8,078,043  $12,755,293  $17,596,062  $26,003,897
EBITDA..................  $1,967,930  $3,326,828   $4,348,713  $ 6,393,913  $ 9,968,682
Lines sold to date......      21,082      30,385       41,316       68,184       85,329
Lines in service to
 date(1)................      14,528      24,357       33,188       52,011       70,572
Estimated data lines (%
 of installed lines)....          83%         81%          69%          71%          71%
Lines on switch (%).....         100%        100%         100%         100%         100%
Customer lines colocated
 (%)....................         N/A         N/A          N/A          N/A           48%
ILEC central offices
 interconnected.........         N/A         249          297          340          443
ILEC central office
 colocations in service
 and under development..           0           0            0            0           23
Average monthly revenue
 per line...............        $155        $139         $148         $138         $141
Quarterly minutes of use
 switched (in millions).         402         683        1,039        1,444        2,033
Markets in operation....           2           2            6           10           12
MSAs served.............           6           6           13           29           31
Switches operational....           2           2            4            6            7
Focal customer
 colocation space in
 service (square feet)..         N/A       2,938        9,882       23,302       29,282
Capital expenditures (in
 millions)..............          $8         $13          $24          $21          $24
Employees...............          82         131          186          233          312
</TABLE>
- --------
(1)  Does not include approximately 12,000 access lines in Boston that are being
     managed by us on behalf of Level 3 Communications as a result of our
     purchase of Level 3's switch in January of 1999. These lines are expected
     to eventually migrate to Level 3's network.
 
     Although we have generated positive EBITDA in the most recent six quarters,
we anticipate that as a result of the recent operating and regulatory trends
described above, we may experience negative EBITDA for a period of time until
these trends stabilize and operating activities in our newer markets mature.
 
 Three Months Ended March 31, 1999 Compared to Three Months Ended March 31, 1998
 
     Total revenues for the three months ended March 31, 1999 were $26.0 million
compared to $5.1 million for the three months ended March 31, 1998. This $20.9
million increase is primarily due to our rapid growth in our Chicago and New
York markets. Customer service and network operations expenses totaled $10.4
million for the first quarter of 1999 compared to $1.8 million for the first
quarter of 1998. This increase resulted from our rapid expansion and related
costs for leased facilities, usage settlements, customer care and operational
personnel, equipment maintenance and other operating expenses. Selling, general
and administrative expense also increased due to our expansion from $1.3
million during the three months ended March 31, 1998 to $5.7 million during the
most recent three month period. Similarly, depreciation and amortization
increased from $0.9 million to $4.0 million in the comparative periods as a
result of a significant increase in the level of fixed assets we put into
service between April 1, 1998 and March 31, 1999. Non-cash compensation expense
was $0.4 million for the first quarter of 1999 compared to $0.3 million for the
first quarter of 1998. The increase in non-cash compensation expense is the
result of the September 30, 1998 amendments of vesting agreements with some of
our executive officers. 

     Interest income increased from $1.0 million in the three months ended March
31, 1998, to $1.3 million in the three months ended March 31, 1999 due to our
receiving interest income from the Notes proceeds for only half of the first
quarter of 1998. Interest expense increased from $2.1 million in the first
quarter of 1998 to $5.4 million in the first quarter of 1999. This increase is
due to an additional $2.9 million of amortization of our Notes and $0.4 million
of interest expense on our secured equipment term loan that was entered into
during December 1998. Interest on the Notes is not payable in cash until August
2003.
 

<PAGE>
 
Liquidity and Capital Resources
 
     We intend to continue to increase our coverage of major U.S. cities by
expanding our services to four additional markets in 1999 and another four
markets in 2000. This business plan will require that we expand our existing
networks and services, deploy our own fiber capacity in a majority of our
markets and fund our initial operating losses. We will require significant
capital to fund the purchase and installation of telecommunications switches,
equipment, infrastructure and fiber facilities and/or long-term rights to use
fiber transport capacity. The implementation of this plan requires significant 
capital expenditures, a substantial portion of which will be incurred
before significant related revenues from our new markets are expected to be
realized. These expenditures, together with associated early operating
expenses, may result in our having substantial negative operating cash flow and
substantial net operating losses for the foreseeable future, including in 1999
and 2000. Although we believe that our cost estimates and the scope and timing
of our build-out are reasonable, we cannot assure you that actual costs or the
timing of the expenditures, or that the scope and timing of our build-out, will
be consistent with current estimates.
 
     Our capital expenditures were approximately $24.5 million for the first
quarter of 1999, primarily reflecting capital spending for the build-out of our
planned markets, including the $7.7 million acquisition of network assets and
associated infrastructure from Level 3 Communications for our Boston market. We
estimate that our capital expenditures in connection with our business plan will
be approximately $125 million for the remainder of 1999. The 1999 expenditures
are expected to be made primarily for the build-out of additional markets, the
expansion of our existing markets and services, including high-speed data
services, and the purchase of local fiber transport capacity in a majority of
our markets.
 
     We estimate that the implementation of our business plan, as currently
contemplated, including the remaining 1999 capital expenditures previously
described, operating losses in newer markets and working capital needs, will
require approximately $230 million from April 1, 1999 through the third quarter
of 2000. We plan to fund these capital requirements with cash, cash
equivalents and short-term investments currently on hand, borrowing capacity
under our $50 million equipment term loan facility (described below),
anticipated cash flows from future operations and the net proceeds from
potential future equity or debt offerings.

     Our business plan, and our expectations of our future capital requirements
and cash flows from operations, are based on current estimates. Our actual
capital expenditures and cash flows could differ significantly from these
estimates. If we require additional capital to complete our budgeted expansion
or if customer demand significantly differs from our current expectations, our
funding needs may increase. In addition, we may be unable to produce sufficient
cash flows from ongoing operations or net proceeds from equity or debt
financings to fund our business plan and future growth. This would require us
to alter our business plan, including delaying or abandoning our future
expansion or spending plans, which could have a material adverse effect on our
business. In addition, we may elect to pursue other attractive business
opportunities, including accelerating the pace or expanding the geographic scope
of our build-out, that could require additional capital investments in our
networks. If any of these events were to happen, we could incur additional
borrowings, issue additional debt or equity securities or enter into joint
ventures.

     We cannot assure you that we will be successful in producing sufficient
cash flows or raising sufficient debt or equity capital on terms that we will
consider acceptable. Further, there can be no assurance that expenses will not
exceed our estimates or that the funds needed will not likewise be higher than
estimated. Failure to generate sufficient funds may require us to delay, abandon
or reduce the scope of our future expansion or expenditures, which could have a
material adverse effect on the implementation of our business plan and our
results of operations.
 
     Net cash used in operating activities for the three months ended March 31,
1999 was $1.3 million, a decrease of $5.0 million from the same period in 1998.
This decrease is primarily the result of the $3.7 million in income taxes we
paid during the first quarter of 1999 and the increase in the change in accounts
receivable between comparable periods totaling $3.3 million, which was offset by
increased depreciation and amortization of $3.1 million during the first quarter
of 1999. Net cash used in investing activities for the first quarter of 1999 was
$24.0 million compared to $7.6 million in the first quarter of 1998. This
increase of $16.4 million from the first quarter of 1998 is primarily due to our
build-out of additional markets and includes the $7.7 million acquisition of
network assets and associated infrastructure from Level 3 Communications for our
Boston market. Net cash provided by financing activities for the first quarter
of 1999 was $5.8 million, a decrease of $148.5 million from the first quarter of
1998. This decrease is primarily the result of our receipt of $144.1 million in
net proceeds from the issuance of the Notes during the first quarter of 1998.

     Our Credit Agreement provides that NTFC Capital Corporation will make term
loans to us in an aggregate principal amount of up to $50 million. These loans
are to be used solely for the purchase of telecommunications equipment and
related software licenses. To secure the loans, we have granted a security
interest in the assets acquired with the loans. Loans must be repaid over a 
five-year period from the date of the borrowing, which must be on or prior to
December 31, 1999. Principal and interest payments are due monthly, and interest
accrues based on the five-year swap rate, plus additional basis points. Interest
will accrue at a lower rate if we meet specified financial tests. As of March
31, 1999, we had $24.5 million outstanding under this term loan facility.
 
     We have historically incurred net losses and have an accumulated deficit of
$9.9 million as of March 31, 1999. Most recently, we funded a large portion of
our future operating losses and capital expenditures through the 1998 offering
of the Notes and by other financings. On February 18, 1998, we received $150
million in gross proceeds from the sale of the Notes. The Notes will accrete to
an aggregate stated principal amount of $270 million by February 15, 2003. As of
March 31, 1999, the principal amount of the Notes had accreted to approximately
$171.1 million. No interest is payable on the Notes prior to August 15, 2003.
Thereafter, cash interest will be payable semiannually on August 15 and February
15 of each year.


<PAGE>
 

Impact of the Year 2000 Issue
 
     The year 2000 issue results from computer programs being written using two
digits rather than four to define the year. Any of our computer programs or
systems, or those of our suppliers, that have date-sensitive software may
recognize a date using "00" as the year 1900 rather than the year 2000. This
could result in a system failure or miscalculation causing disruption of
operations, including, among other things:
 
     .  A temporary inability to process transactions
 
     .  A temporary inability to send invoices
 
     .  A temporary inability to engage in normal business activities
 
     .  Interruptions of customer service
 
     Our Year 2000 compliance program can be divided into several phases. These
phases include:
 
     .  Assessing our material information systems and hardware for Year 2000
        readiness
 
     .  Assessing the Year 2000 readiness of third parties with whom we have
        significant business relationships and on whose systems and hardware we
        rely
 
     .  Contingency planning
 
     As part of our internal assessment phase, we examined our material
information systems, including our DMS-500 SuperNode central office switches,
and hardware to determine whether these systems and hardware are Year 2000
compliant. However, we have not nor do we plan to identify, validate as
compliant or remediate integrated circuits in any other systems or hardware. We
have received assurances from all of our major software and hardware vendors
that the products we use are Year 2000 compliant in all material respects and
will function adequately after December 31, 1999.
 
     Our services are also dependent on network systems and transport facilities
maintained by other carriers, including incumbent local exchange carriers and
interexchange carriers. We are in the process of assessing the Year 2000
compliance status of other carriers with whom we have material relationships.
Our assessment relies, without any independent verification, on the statements
and assumptions underlying the statements these carriers have made in their
periodic reports filed with the Securities and Exchange Commission. The risks
associated with the failure of these carriers' systems or transport facilities
include potential interruption of service, including blocked calls and delayed
call completion. Interruptions of this type would heavily impact our customers
and, if prolonged, could have a material adverse effect on our business,
financial condition or results of operations.
 
     Because we currently lease 100% of our transport facilities, we are
dependent on the availability of fiber transport facilities owned by other
carriers. There are few, if any, contingency measures we can take if Year 2000
problems cause these carriers' facilities to fail. We lease transport
facilities from multiple carriers in each market in which we operate in an
attempt to provide redundancy and diversity in service. However, we cannot
assure you that there will not be multiple network failures in a particular
market. If our transport vendors experience facilities failures, our business
may be disrupted and we may suffer a material adverse effect.
 
     To date, we have spent approximately $0.2 million on our Year 2000
compliance program. We expect future Year 2000 remediation expenditures to
total approximately $0.3 million. All of these costs will be expensed as they
are incurred.
 
     We intend to continue our Year 2000 compliance assessment of our software.
If it comes to our attention that any of our software is not Year 2000
compliant, we intend to develop an action plan and further assess the risks of
non-compliance and the resources that would be required to resolve the problem.
We also intend to develop contingency plans to the extent we believe those
plans would be useful.
<PAGE>

 
     Based on our current schedule for completion of our Year 2000 compliance
program, we believe that our planning is adequate to secure Year 2000 readiness
of our critical systems. Nevertheless, Year 2000 readiness is subject to a
number of risks and uncertainties, some of which, like the readiness of other
carriers upon whom we rely, are out of our control. We are not able to predict
all the factors that could cause actual results to differ materially from our
current expectations about Year 2000 readiness. The cost of our Year 2000
compliance program is based upon our management's best estimate. At this time,
we believe that the major risks associated with an inability of our systems or
software to process Year 2000 data correctly are a system failure or
miscalculation causing a disruption of business activities or interruptions in
customer service. If we, or third parties with whom we have significant business
relationships, fail to achieve Year 2000 readiness with respect to critical
systems, there could be a material adverse effect on our business, financial
condition or results of operations.
 
     The discussions under "Management's Discussion and Analysis of Financial
Condition and Results of Operations" contain forward-looking statements. These 
forward-looking statements are subject to risks and uncertainties, including 
financial and regulatory developments and industry growth and trend projections,
that could cause actual events or results to differ materially from those 
expressed or implied by the statements. The most important factors that could 
impact the variability of future results include, but are not limited to, our 
failure to:

     .  Prevail in legal and regulatory proceedings regarding reciprocal
        compensation for Internet-related calls or changes to laws and
        regulations that govern reciprocal compensation

     .  Raise sufficient capital on terms we consider acceptable and on a timely
        basis

     .  Successfully expand our operations into new geographic markets on a 
        timely and cost-effective basis

     .  Successfully introduce and expand our data and voice service offerings
        on a timely and cost-effective basis

     .  Respond to competitors in our existing and planned markets

     .  Execute and renew interconnection agreements with incumbent carriers on 
        terms satisfactory to us

     .  Maintain our agreements for transport facilities

     .  Maintain acceptance of our services by new and existing customers

     .  Attract and retain talented employees

     .  Obtain and maintain any required governmental authorizations, franchises
        and permits, all in a timely manner, at reasonable costs and on
        satisfactory terms and conditions

     .  Respond effectively to regulatory, legislative and judicial developments

     .  Manage administrative, technical and operational issues presented by our
        expansion plans

     .  Address Year 2000 remediation issues

Quantitative and Qualitative Disclosures about Market Risk
 
     We are exposed to minimal market risks. We manage sensitivity of our
results of operations to these risks by maintaining a conservative investment
portfolio, which primarily consists of debt securities, typically maturing
within one year, and entering into long-term debt obligations with appropriate
pricing and terms. We do not hold or issue derivative, derivative commodity or
other financial instruments for trading purposes. Financial instruments held for
other than trading purposes do not impose a material market risk on us.

     We are exposed to interest rate risk, as additional financing is
periodically needed due to the large operating losses and capital expenditures
associated with establishing and expanding our network coverage. The interest
rate that we will be able to obtain on debt financing will depend on market
conditions at that time, and may differ from the rates we have secured on our
current debt.










<PAGE>

                           PART II--OTHER INFORMATION

Item 1. Legal and Administrative Proceedings

     With the exception of the matters discussed in our December 31, 1998 Annual
Report on Form 10-K, filed on March 31, 1999, as amended by Form 10-K/A filed on
April 7, 1999, we are not aware of any material litigation against us. In the
ordinary course of our business, we are involved in a number of regulatory
proceedings before various state commissions and the FCC.

Item 2. Changes in Securities and Use of Proceeds

     On March 15, 1999, we issued 300 shares of our Class A Common Stock to one
of our Directors for an aggregate purchase price of $472,500. No underwriter was
engaged in connection with this sale, and the sale was exempt from registration
under the Securities Act of 1933, as amended (the "Securities Act"), pursuant
to Section 4(2) of the Securities Act, as a transaction not involving any public
offering. 

     On March 27, 1999, we issued 72.25 shares of our Class A Common Stock to
one of our employees upon the exercise of stock options granted under our 1997
Non-Qualified Stock Option Plan for an aggregate purchase price of $69,352.50.
No underwriter was engaged in connection with this sale, and the sale was exempt
from registration under the Securities Act of 1933, as amended (the "Securities
Act"), pursuant to Section 4(2) of the Securities Act, as a transaction not
involving any public offering, or Rule 701 of the Securities Act, as a sale of 
securities pursuant to certain compensatory benefit plans.

Item 4. Submission of Matters to a Vote of Security Holders

     Pursuant to a written consent of our stockholders dated February 16, 
1999, effected in accordance with the General Corporation Law of the State of 
Delaware, our stockholders voted to increase the number of authorized shares of 
our Class A Common Stock from 85,567 to 100,000.
<PAGE>

Item 6. Exhibits and Reports on Form 8-K

     (a)   Exhibits


<TABLE>
<CAPTION>
     Exhibit
     -------                        EXHIBIT DESCRIPTION                                      LOCATION
     Number       -----------------------------------------------------------             --------------
     -------
<S>               <C>                                                                    <C>
      10.1        Interconnection Agreement with Bell-Atlantic-District of               Filed herewith
                  Columbia dated October 1, 1998.

      10.2        Interconnection Agreement with Bell-Atlantic-Maryland dated            Filed herewith
                  October 2, 1998.

      10.3        Interconnection Agreement with Bell-Atlantic-Virginia dated            Filed herewith
                  October 2, 1998.

      10.4        Interconnection Agreement with U.S. West-Washington State              Filed herewith
                  dated January 15, 1999.

      10.5        Interconnection Agreement with Ameritech Information Industry          Filed herewith
                  Services, on behalf of and as agent for Ameritech Michigan
                  dated February 10, 1999.

      10.6        Interconnection Agreement with Bell-Atlantic-Massachusetts             Filed herewith
                  dated February 15, 1999.

      10.7        Amendment No. 3 to Network Products Purchase Agreement with            Filed herewith
                  Northern Telecom Inc., dated March 25, 1999.*

      10.8        Purchase Agreement with XCOM Technologies, Inc., dated January         Filed herewith
                  6, 1999.*

      10.9        Fifth Amendment to Lease Agreement for property located at 200         Filed herewith
                  North LaSalle, Chicago, IL, dated October 14, 1998.

      10.10       Sixth Amendment to Lease Agreement for property located at 200         Filed herewith
                  North LaSalle, Chicago, IL, dated February 18, 1999.

      10.11       First Amendment to Lease Agreement for property located at 650         Filed herewith
                  Townsend Street, San Francisco, CA, dated March 3, 1998.

      10.12       Second Amendment to Lease Agreement for property located at            Filed herewith
                  650 Townsend Street, San Francisco, CA, dated June 16, 1998.

      10.13       Third Amendment to Lease Agreement for property located at 650         Filed herewith
                  Townsend Street, San Francisco, CA, dated February 16, 1999.

      10.14       Lease Agreement for property located at 1950 Stemmons Freeway,         Filed herewith
                  Dallas, TX, dated December 15, 1998.

      10.15       Lease Agreement for property located at One Main Street,               Filed herewith
                  Cambridge, MA, dated January 6, 1999.

      10.16       Lease Agreement for property located at 250 Williams Street,           Filed herewith
                  Atlanta, GE, dated February 5, 1999.

      10.17       Lease Agreement for property located at Christopher Columbus           Filed herewith
                  Drive & Washington Street, Jersey City, NJ, dated February
                  19, 1999.

      27.1        Financial Data Schedule.                                               Filed herewith
</TABLE>

(*) Portions of this exhibit have been omitted pursuant to a request for
confidential treatment, and the omitted portions have been filed separately with
the Securities and Exchange Commission.



<PAGE>
 

                                  SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.

                                  Focal Communications Corporation

Date:   May 7, 1999        
                                 /s/ Robert C. Taylor, Jr.

                                     Robert C. Taylor, Jr.,
                            President and Chief Executive Officer
                                     (Authorized Officer)


Date:   May 7, 1999        
                                 /s/ Joseph A. Beatty

                                     Joseph A. Beatty,
                               Executive Vice President and
                                 Chief Financial Officer
                              (Principal Financial Officer)


Date:   May 7, 1999        
                                 /s/ Gregory J. Swanson 

                                     Gregory J. Swanson,
                                      Controller
                              (Principal Accounting Officer)

<PAGE>
 
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996



                          DATED AS OF OCTOBER 1, 1998



                                BY AND BETWEEN


                    BELL ATLANTIC - WASHINGTON, D.C., INC.


                                      AND


                       FOCAL COMMUNICATIONS CORPORATION
                              OF THE MID-ATLANTIC



<PAGE>
 
         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement (this "Agreement"), under Sections 251 and
252 of the Telecommunications Act of 1996 (the "Act"), is effective as of the
1/st/ day of October (the "Effective Date"), by and between Bell Atlantic -
Washington, D.C., Inc. ("BA"), a New York corporation with offices at 1710 H.
Street, N.W., Washington, D.C. 20006, and Focal Communications Corporation of
the Mid-Atlantic ("Focal"), a Delaware corporation with offices at 200 N.
LaSalle Street, Suite 800, Chicago, Illinois 60601 (each a "Party" and,
collectively, the "Parties").

     WHEREAS, Focal has requested that BA make available to Focal
Interconnection, service and unbundled Network Elements upon the same terms and
conditions as provided in the Interconnection Agreement (and amendments thereto)
between MFS Intelenet of Washington, D.C., Inc. and BA, dated as of July 16,
1996 (revised as of July 29, 1997), for the District of Columbia, approved by
the Commission under Section 252 of the Act (the "Separate Agreement") and
attached as Appendix 1 hereto; and

     WHEREAS, BA has undertaken to make such terms and conditions available to
Focal hereby only because and, to the extent required by, Section 252(i) of the
Act.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Focal and BA hereby agree as follows:

     1.0  INCORPORATION OF APPENDICES BY REFERENCE

     1.1  Except as expressly stated herein, the terms and conditions of the
Separate Agreement (as set forth in Appendix 1 hereto), as it is in effect on
the date hereof after giving effect to operation of law, and of the other
Appendices hereto, are incorporated by reference in their entirety herein and
form an integral part of this Agreement.

     1.2  References in Appendix 1 hereto to MFS Intelenet of Washington, D.C.,
Inc. or to MFS shall for purposes of this Agreement be deemed to refer to Focal.

     1.3  References in Appendix 1 hereto to the "Effective Date", the date of 
effectiveness thereof and like provisions shall for purposes of this Agreement 
be deemed to refer to the date first written above. Unless terminated earlier in
accordance with the terms of Appendix 1 hereto, this Agreement shall continue in
effect until the Separate Agreement expires or is otherwise terminated.
<PAGE>
 
     1.4  The Joint Plan referred to in Section 10.1 of Appendix 1 hereto shall 
be developed upon the request of either Party within a reasonable amount of time
after receipt of such request.

     1.5  Notwithstanding Section 27.5 of Appendix 1 hereto, at such time as BA 
makes available the Performance Monitoring Reports set forth in the Memorandum 
Opinion and Order adopted by the FCC on August 14, 1997 (the "FCC Merger Order")
to other Telecommunications Carriers purchasing Interconnection from BA, BA 
shall provide Focal with the Performance Monitoring Reports applicable to Focal 
in accordance with the requirements of said FCC Merger Order.

     1.6  All notices, affidavits, exemption-certificates or other 
communications to Focal under Section 29.6.6 of Appendix 1 hereto shall be sent 
to the following address:

          Focal Communications Corporation of the Mid-Atlantic
          Attn: Corporate Tax Department
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone: (312) 895-8400

     1.7  All notices, affidavits, exemption-certificates or other
communications to BA under Section 29.6.6 of Appendix 1 hereto shall be sent to
the following address:

          Tax Administration
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          Room 3109
          New York, New York 10036

     1.8  Notices to Focal under Section 29.10 of Appendix 1 hereto shall be 
sent to the following address:

          Focal Communications Corporation of the Mid-Atlantic
          Attn: Senior Manager - Carrier Relations
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone: (312) 895-8400

     1.9  Notices to BA under Section 29.10 of Appendix 1 hereto shall be sent 
to the following address:

                                       2
<PAGE>
 
               President - Telecom Industry Services                         
               Bell Atlantic Corporation                       
               1095 Avenue of the Americas                     
               40/th/ Floor                                      
               New York, New York 10036                        
               Facsimile: (212) 597-2585                       
                                                               
               with a copy to:                                 
                                                               
               Bell Atlantic Network Services, Inc.            
               Attn: Mr. Jack H. White,                        
                Associate General Counsel                      
               1320 N. Court House Road, 8/th/ Floor             
               Arlington, Virginia 22201                       
               Facsimile: (703) 974-0744                       
                                                               
               with a copy to:                                 
                                                               
               Vice President and General Counsel              
               Bell Atlantic - Washington, D.C., Inc.          
               1710 H. Street, N.W.                            
               11/th/ Floor                                      
               Washington, D.C. 20006                          
               Facsimile: (202) 887-9195                        

     1.10      Schedules 3.0 and 4.0 set forth at Appendix 2 hereto shall
replace and supersede in their entirety Schedules 3.0 and 4.0 of Appendix 1
hereto.

     2.0       CLARIFICATIONS

     2.1       The entry into, filing and performance by BA of this Agreement 
does not in any way constitute a waiver by BA of any of the rights and remedies 
it may have to seek review of any of the provisions of the Separate Agreement, 
or to petition the Commission, other administrative body or court for 
reconsideration or reversal of any determination made by any of them, or to seek
review in any way of any portion of this Agreement in connection with Focal's 
election under Section 252(i) of the Act.

                                       3

<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be 
executed as of this 1/st/ day of October, 1998.


FOCAL COMMUNICATIONS                  BELL ATLANTIC-
 CORPORATION OF THE                    WASHINGTON, D.C., INC.
 MID-ATLANTIC

By: /s/ John R. Barnicle              By: /s/ Jeffrey A. Masoner
   -----------------------               --------------------------
Printed: JOHN R. BARNICLE             Printed: Jeffrey A. Masoner
        ------------------                    ---------------------
Title:  E.V.P. - C.O.O.               Title: Vice-President - Interconnection 
      --------------------                   --------------------------------
                                             Services Policy & Planning
                                             --------------------------

                                       4

<PAGE>
 



                                  APPENDIX 1


<PAGE>
 
 
         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996


                           DATED AS OF JULY 16, 1996



                                BY AND BETWEEN



                         BELL ATLANTIC-VIRGINIA, INC.

                                      AND

                        MFS INTELENET OF VIRGINIA, INC.





<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------

<TABLE> 
<CAPTION> 
                                                                            Page
                                                                            ----
<S>                                                                         <C> 
1.0  DEFINITIONS                                                              2

2.0  INTERPRETATION AND CONSTRUCTION                                         10

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION
     SCHEDULE                                                                11

4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)                           11
4.1  Scope                                                                   12
4.2  Physical Architecture                                                   13
4.3  Initial Architecture                                                    13
4.4  Interconnection in Additional LATAs                                     14
4.5  Interconnection Points for Different Types of Traffic                   15

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE
     TRAFFIC PURSUANT TO SECTION 251(c)(2)                                   15
5.1  Scope of Traffic                                                        15
5.2  Trunk Group Connections and Ordering                                    15
5.3  Additional Switching System Hierarchy and Trunking Requirements         15
5.4  Signaling                                                               16
5.5  Grades of Service                                                       16
5.6  Measurement and Billing                                                 16
5.7  Reciprocal Compensation Arrangements -- Section 251(b)(5)               17

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC
     PURSUANT TO 251(c)(2)                                                   18
6.1  Scope of Traffic                                                        18
6.2  Trunk Group Architecture and Traffic Routing                            18
6.3  Meet-Point Billing Arrangements                                         19
6.4  800/888 Traffic                                                         21

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC                     22
7.1  Information Services Traffic                                            22
7.2  LSV/VCI Traffic                                                         23
7.3  Transit Service                                                         24
7.4  911/E911 Arrangements                                                   25
7.5  Ancillary Traffic Generally                                             26

8.0  NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS                       26
</TABLE> 
<PAGE>
 
<TABLE> 
     <S>                                                                                   <C> 
     9.0   NETWORK MAINTENANCE AND MANAGEMENT; OUTRAGES                                    26

     9.3   Interference or Impairment                                                      28
     9.4   Repeated or Willful Noncompliance                                               28
     9.5   Outage Repair Standard                                                          28
     9.6   Notice of Changes -- Section 251(c)(5)                                          28  
     
     10.0  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND
           INSTALLATION, MAINTENANCE, TESTING AND REPAIR                                   28
     10.1  Joint Network Reconfiguration and Grooming Plan                                 28  
     10.2  Installation, Maintenance, Testing and Repair                                   29
     10.3  Forecasting Requirements for Trunk Provisioning                                 29
     
     11.0  UNBUNDLED ACCESS -- SECTION 251(c)(3)                                           30  
     11.1  Unbundled Local Loop (ULL) Transmission Types                                   30
     11.2  Port Types                                                                      31
     11.3  Trunk Side Local Transport                                                      32
     11.4  Limitations on Unbundled Access                                                 32
     11.5  Availability of Other Network Elements on an Unbundled Basis                    33 
     11.6  Provisioning of Unbundled Local Loops                                           33
     11.7  Maintenance of Unbundled Local Loops                                            35   
     11.8  Rates and Charges                                                               35

     12.0  RESALE -- SECTIONS 251(c)(4) and 251(b)(1)                                      35
     12.1  Availability of Retail Rates for Resale                                         35
     12.2  Availability of Wholesale Rates for Resale                                      35
     
     13.0  COLLOCATION -- SECTION 251(c)(6)                                                36
     
     14.0  NUMBER PORTABILITY -- SECTION 251(b)(2)                                         37   
     14.1  Scope                                                                           37    
     14.2  Procedures for Providing INP Through Remote Call Forwarding                     38
     14.3  Procedures for Providing INP Through Direct Inward Dial Trunks (Flex-DID)       39
     14.4  Procedures for Providing LTNP Through Full NXX Code Migration                   39  
     14.5  Receipt of Terminating Compensation on Traffic to INP'ed Numbers                39    
     14.6  Recovery of INP Costs Pursuant to FCC Order and Rulemaking                      40
     

     15.0  DIALING PARITY -- SECTION 251(b)(3)                                             41
     
     16.0  ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                                    41    

     17.0  DATABASES AND SIGNALING                                                         41
</TABLE> 

                                      ii
<PAGE>
 
<TABLE> 
<S>                                                                          <C> 
18.0   COORDINATED SERVICE ARRANGEMENTS                                      42
18.1   Intercept and Referral Announcements                                  42
18.2   Coordinated Repair Calls                                              43
18.3   Customer Authorization                                                43

19.0   DIRECTORY SERVICES ARRANGEMENTS                                       43
19.1   Directory Listings and Directory Distributions                        44
19.2   Yellow Page Maintenance                                               45
19.3   Service Information Pages                                             45
19.4   Directory Assistance (DA); Call Completion                            46

20.0   COORDINATION WITH TARIFF TERMS                                        45
                                       
21.0   INSURANCE                                                             46
                                       
22.0   TERM AND TERMINATION                                                  47

23.0   DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                          48
                                                          
24.0   CANCELLATION CHARGES                                                  48
                                                          
25.0   INDEMNIFICATION                                                       48
                                                          
26.0   LIMITATION OF LIABILITY                                               49

27.0   PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                        50
27.1   Certain Definitions                                                   50
27.2   Performance Standards                                                 51
27.3   Limitations                                                           51
27.4   Service Quality Standards                                             52
27.5   Records                                                               52

28.0   COMPLIANCE WITH LAWS; REGULATORY APPROVAL                             52

29.0   MISCELLANEOUS                                                         53
29.1   Authorization                                                         53
29.2   Independent Contractor                                                53
29.3   Force Majeure                                                         53
29.4   Confidentialty                                                        54
29.5   Choice of Law                                                         55
29.6   Taxes                                                                 55
29.7   Assignment                                                            57
29.8   Billing and Payment; Disputed Amounts                                 57
29.9   Dispute Resolution                                                    58
29.10  Notices                                                               59
</TABLE> 

<PAGE>
 
29.11     Section 252(i) Obligations                                       59
29.12     Joint Work Product                                               60
29.13     No Third Party Beneficiaries; Disclaimer of Agency               61
29.14     No License                                                       61
29.15     Technology Upgrades                                              61
29.16     Survival                                                         62
29.17     Entire Agreement                                                 62
29.18     Counterparts                                                     62
29.19     Modification, Amendment, Supplement or Waiver                    62
29.20     Successors and Assigns                                           62
29.21     Publicity                                                        62

                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------

Schedules
- ---------

Schedule 1.0   Certain Terms As Defined in the Act, As of July 16, 1996
Schedule 3.0   Implementation Schedule 
Schedule 4.0   Interconnection Points in LATA
Schedule 4.2   Physical Architecture Diagram
Schedule 4.3   Initial Architecture Diagram 
Schedule 4.5   Interconnection Points for Different Types of Traffic
Schedule 6.3   Rate Elements Under Meet Point Billing
Schedule 27.0  Performance Interval Dates for Specified Activities
Schedule 27.1  MFS Service Quality Standards

Exhibits
- --------

Exhibit A      Detailed Schedule of Itemized Charges 
Exhibit B      Network Element Bona Fide Request 
Exhibit C      Directory Assistance and Call Completion Services Agreement
<PAGE>
 
         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement under Sections 251 and 252 of the 
Telecommunications Act of 1996, is effective as of the 16th day of July, 1996 
(the "Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched
Exchange Access Services, and other Telecommunications Services (all as defined
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the 
respective obligations of the Parties and the terms and conditions under which 
the Parties will interconnect their networks and provide other services as 
required by the Act (as defined below) and additional services as set forth 
herein; and 

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996 
have specific requirements for interconnection, unbundling, and service resale, 
commonly referred to as the "Checklist", and the Parties intend that this 
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein 
and other good and valuable consideration, the receipt and sufficiency of which 
are hereby acknowledged, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA 
and MFS (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements,
ancillary services, and wholesale Telecommunications Services available for
resale within each LATA in which they both operate within Virginia. As such,
this Agreement is an integrated package that reflects a balancing of interests
critical to the Parties. It will be submitted to the Virginia State Corporation
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of
the Agreement. So long as the Agreement remains in effect, neither Party shall
advocate before any legislative, regulatory, or other public forum that any term
of this Agreement be modified or eliminated, unless otherwise mutually agreed by
the Parties.
<PAGE>
 
1.0  DEFINITIONS.

     As used in this Agreement, the following terms shall have the meanings 
specified below in this Section 1.0. For convenience of reference only, the 
definitions of certain terms that are As Defined in the Act (as defined below) 
are set forth on Schedule 1.0.

     1.1   "Act" means the Communications Act of 1934 (47 U.S.C 151 et, seq,),
                                                                    --  ---
as amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission.

     1.2  "ADSL" or "Asymmetrical Digital Subscriber Line" means a transmission 
technology which transmits an asymmetrical digital signal of up to 6 mbps to the
Customer and up to 640kbps from the Customer.

     1.3  [Reserved]

     1.4  "Agreement" means this Interconnection Agreement under Sections 251 
and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5  "Ancillary Traffic," means all traffic that is destined for ancillary 
services, or that may have special billing requirements, including but 
not limited to the following: LSV/VCI, Directory Assistance, 911/E911, Operator 
Services (call completion), 800/888 database query, LIDB, and information 
services requiring special billing.

     1.6  "As Defined in the Act" means as specifically defined by the Act and 
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     1.7  "As Described in the Act" means as described in or required by the Act
and as from time to time interpreted in the duly authorized rules and 
regulations of the FCC or the Commission.

     1.8  "Automatic Number Identification" or "ANI" means a Feature Group D 
signaling parameter which refers to the number transmitted through a network 
identifying the billing number of the calling party.

     1.9  "Calling Party Number" or "CPN" is a Common Channel Signaling ("CCS") 
parameter which refers to the number transmitted through a network identifying 
the calling party.

     1.10 "Central Office Switch" means a switch used to provide 
Telecommunications Services, including, but not limited to:

          (a)  "End Office Switch" or "End Office" which is used to terminate 
Customer station Loops for the purpose of interconnection to each other and to 
trunks; and 
<PAGE>
 
          (b) "Tandem Switch" or "Tandem Office" which is a switching entity
that is used to connect and switch truck circuits between and among End Office
Switches and between and among End Office Switches and carriers' aggregation
points, points of termination, or points of presence. An "Access Tandem Office"
or "Access Tandem" is a Tandem Office with billing and recording capabilities
that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End 
Office/Tandem Office Switch.

     1.11 [Reserved]

     1.12 "CLASS Features" means certain CCS-based features available to 
Customers including, but not limited to: Automatic Call Back; Call Trace; Caller
Identification, and future offerings.

     1.13 "Collocation" means an arrangement whereby one Party's (the 
"Collocating Party") facilities are terminated in equipment necessary for 
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a 
second Party (the "Housing Party"). For purposes of Collocation, the "premises" 
of a Housing Party is limited to a Housing Party Wire Center, other mutually 
agreed-upon locations of the Housing Party, or any other location for which 
Collocation has been ordered by the FCC or Commission. Collocation may be 
"physical" or "virtual". In "Physical Collocation," the Collocating Party 
installs and maintains its own equipment in the Housing Party's premises. In 
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA
currently provides Collocation under terms, rates, and conditions as described 
in tariffs on file or soon to be filed with the FCC and the Commission. Upon 
request by either Party, BA and MFS will address the provision of additional 
types of Collocation arrangements, including additional physical locations and 
alternative utilizations of space and facilities.

     1.14 "Commission" means the Virginia State Corporation Commission.

     1.15 "Common Channel Signaling" or "CCS" means a method of transmitting 
call set-up and network control data over a digital signaling network separate 
from the public switched telephone network facilities that carry the actual 
voice or data traffic of the call. "SS7" means the common channel out of band 
signaling protocol developed by the Consultative Committee for International 
Telephone and Telegraph ("CCITT") and the American National Standards Institute 
("ANSI"). BA and MFS currently utilize this out-of-band signaling protocol. 
"CCSAC" or "CCSAS" means the common channel signaling access connection or 
service, respectively, which connects one Party's signaling point of 
interconnection ("SPOI") to the other Party's STP for the exchange of SS7 
messages.
<PAGE>
 
     1.16 "Competing Local Exchange Carrier" or "CLEC" means any Local Exchange 
Carrier other than BA, operating as such in BA's certificated territory in 
Virginia. MFS is or will shortly become a CLEC.

     1.17 "Cross Connection" means a jumper cable or similar connection provided
pursuant to Collocation at the digital signal cross connect, Main Distribution 
Frame or other suitable frame or panel between (i) the Collocating Party's 
equipment and (ii) the equipment or facilities of the Housing Party.

     1.18 "Customer" means a third-party residence or business subscriber to 
Telecommunications Services provided by either of the Parties.

     1.19 "Dialing Parity" is As Defined in the Act.

     1.20 "Digital Signal Level" means one of several transmission rates in the 
time-division multiplex hierarchy.

     1.21 "Digital Signal Level O" or "DS0" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.

     1.22 "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level 
signal in the time-division multiplex hierarchy. In the time-division 
multiplexing hierarchy of the telephone network, DSI is the initial level of 
multiplexing.

     1.23 "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level in
the time-division multiplex hierarchy. In the time-division multiplexing 
hierarchy of the telephone network, DS3 is defined as the third level of 
multiplexing.

     1.24 "Exchange Access" is As Defined in the Act.

     1.25 "Exchange Message Record" or "EMR" means the standard used for 
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is 
contained in BR-010-200-010 CRIS Exchange Message Record, a Bell Communications 
Research, Inc. ("Bellcore") document that defines industry standards for 
Exchange Message Records.

     1.26 [Reserved]

     1.27 "FCC" means the Federal Communications Commission.

     1.28 "HDSL" or "High-Bit Rate Digital Subscriber Line" means a transmission
technology which transmits up to 784 kbps simultaneously in both directions on a
two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line code.
<PAGE>
 
     1.29 "Independent Telephone Company" or "ITC" means any entity other than 
BA which, with respect to its operations within Virginia, is an "Incumbent Local
Exchange Carrier" As Described in the Act. 

     1.30 "Information Service Traffic" means Local Traffic or IntraLATA Toll 
Traffic which originates on a Telephone Exchange Service line and which is 
addressed to an information service provided over a Party's information 
services platform.

     1.31 "Integrated Digital Loop Carrier" means a subscriber loop carrier 
system which integrates within the switch at a DS1 level that is twenty-four 
(24) loop transmission paths combined into a 1.544 Mbps digital signal. 

     1.32 "Integrated Services Digital Network" or "ISDN" means a switched 
network service providing end-to-end digital connectivity for the simultaneous 
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN") provides 
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B+D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for
digital transmission of twenty three (23) 64 kbps bearer channels and one 16
kbps data and signalling channel (23 B+D).

     1.33 "Interconnection" is as Described in the Act, and means the connection
of separate pieces of equipment or transmission facilities within, between, or
among networks. The architecture of Interconnection may include, but is not
limited to, Collocation Arrangements, entrance facilities, and Mid-Span Meet
arrangements.

     1.34 "Interexchange Carrier" or "IXC" means a carrier that provides, 
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35 "Interim Number Portability" or "INP" means the use of existing and
available call routing, forwarding, and addressing capabilities (e.g. remote
call forwarding) to enable a Customer to receive Telephone Exchange Service
provided by any Local Exchange Carrier operating within the exchange area with
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of
whether the Customer's chosen Local Exchange Carrier is the carrier that
originally assigned the number to the Customer.

     1.36 "InterLATA" is As Defined in the Act.

     1.37 "IntraLATA Toll Traffic" means those intraLATA calls that are not 
defined as Local Traffic in this Agreement. 

     1.38 "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.
<PAGE>
 
     1.39.     "Line Status Verification" or "LSV" means an operator request for
a status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40.     "Lock Access and Transport Area" or "LATA" is As Defined in the 
Act.

     1.41.     "Local Exchange Carrier" or "LEC" is As Defined in the Act. The 
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42.     "Local Serving Wire Center" means a Wire Center that (i) serves 
the area in which the other Party's or a third party's Wire Center, aggregation 
point, point of termination, or point of presence is located, or any Wire Center
in the LATA in which the other Party's Wire Center, aggregation point, point of 
termination or point of presence is located in which the other Party has 
established a Collocation Arrangement or is purchasing an entrance facility, and
(ii) has the necessary multiplexing capabilities for providing transport 
services.

     1.43.     "Local Telephone Number Portability" or "LTNP" means "number 
portability" As Defined in the Act.

     1.44.     "Local Traffic," means traffic that is originated by a Customer 
of one Party on that Party's network and terminates to a Customer of the other 
Party on that other Party's network, within a given local calling area, or 
expanded area service ("EAS") area, as defined in BA's effective Customer 
tariffs. Local Traffic does not include traffic originated or terminated by a 
commercial mobile radio service carrier.

     1.45.     "Main Distribution Frame" or "MDF" means the primary point at 
which outside plant facilities terminate within a Wire Center, for 
interconnection to other telecommunications facilities within the Wire Center.

     1.46. "MECAB" means the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
("OBF"), which functions under the auspices of the Carrier Liaison Committee
("CLC") of the Alliance for Telecommunications Industry Solutions ("ATIS"). The
MECAB document, published by Bellcore as Special Report SR-BDS-000983, contains
the recommended guidelines for the billing of an Exchange Access service
provided by two or more LEC's, or by one LEC in two or more states, within a
single LATA.

     1.47.     "MECOD" means the Multiple Exchange Carriers Ordering and Design 
(MECOD) Guidelines for Access Services - Industry Support Interface, a document 
developed by the Ordering/Provisioning Committee under the auspices of OBF. The 
MECOD document, published by Bellcore as Special Report SR-STS-002643, 
establishes methods for processing orders for Exchange Access service which is 
to be provided by two or more LECs.

     1.48.     "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched 
Exchange Access Service to one
     
                                       6
<PAGE>
 
of the LECs' End Office Switches, with each LEC receiving an appropriate share 
of the transport element revenues as defined by their effective Exchange Access 
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an 
effective Meet-Point Billing arrangement.

     1.49.  "Mid-Span Meet" means an Interconnection architecture whereby two
carriers' fiber transmission facilities meet at a mutually agreed-upon
Interconnection point.

     1.50.  "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff"
means the MPB method whereby each LEC prepares and renders its own meet point
bill in accordance with its own Tariff(s) for the portion of the jointly-
provided Switched Exchange Access Service which the LEC provides.

     1.51.  "Network Element" is As Defined in the Act.

     1.52.  "Network Element Bona Fide Request" means the process described on
Exhibit B that prescribes the terms and conditions relating to a Party's request
that the other Party provide a Network Element not otherwise provided by the
terms of this Agreement.

     1.53.  "North American Numbering Plan" or "NANP" means the numbering plan
used in the United States that also serves Canada, Bermuda, Puerto Rico and
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 3-
digit NXX code and 4-digit line number.

     1.54.  "Numbering Plan Area" or "NPA" is also sometimes referred to as an
area code. There are two general categories of NPAs, "Geographic NPAs" and "Non-
Geographic NPAs." A Geographic NPA is associated with a defined geographic area,
and all telephone numbers bearing such NPA are associated with services provided
within that geographic area. A Non-Geographic NPA, also known as a "Service
Access Code" or "SAC Code," is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55.  "NXX," "NXX Code," or "End Office Code" means the three digit switch
entity indicator (i.e. the first three digits of a seven digit telephone
number).

     1.56.  "Permanent Number Portability" or "PNP" means the use of a database
or other technical solution that comports with regulations issued by the FCC to
provide LTNP for all customers and service providers.

     1.57.  "Port Element" or "Port" means a line card (or equivalent) and
associated peripheral equipment on an End Office Switch which serves as the
Interconnection between individual loops or individual Customer trunks and the
switching components of an End Office Switch and the associated switching
functionality in that End Office Switch. Each Port is typically associated with
one (or more) telephone number(s) which serves as the Customer's network
address.

<PAGE>
 
     1.58 "Rate Center Area" or "Exchange Area" means the specific geographic 
point and corresponding geographic area which has been identified by a given LEC
as being associated with a particular NPA-NXX code assigned to the LEC for its 
provision of Telephone Exchange Services. The Rate Center Area is the exclusive 
geographic area which the LEC has identified as the area within which it will 
provide Telephone Exchange Services bearing the particular NPA-NXX designation 
associated with the specific Rate Center Area. A "Rate Center Point" is a 
specific geographic point, defined by a V&H coordinate, located within the Rate 
Center Area and used to measure distance for the purpose of billing Customers 
for distance-sensitive Telephone Exchange Services and Toll Traffic.

     1.59 "Rate Demarcation Point" means the point of minimum penetration at the
Customer's premises or other point, as defined in a Party's Tariffs, where 
network access recurring charges and LEC responsibility ends and beyond which 
Customer responsibility begins.

     1.60 "Rating Point" or "Routing Point" means a specific geographic point 
identified by a specific V&H coordinate. The Rating Point is used to route 
inbound traffic to specified NPA-NXXs and to calculate mileage measurements for 
distance-sensitive transport charges of switched access services. Pursuant to 
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office
location, or a "LEC Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point/Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point corresponding to each unique and separate Rate Center.

     1.61 "Reciprocal Compensation" is As Described in the Act, and refers to 
the payment arrangements that recover costs incurred for the transport and 
termination of Local Traffic originating on one Party's network and terminating 
on the other Party's network.

     1.62 "Service Control Point" or "SCP" means the node in the common channel 
signaling network to which informational requests for service handling, such as 
routing, are directed and processed. The SCP is a real time database system 
that, based on a query from a service switching point and via a Signaling 
Transfer Point, performs subscriber or application-specific service logic, and 
then sends instructions back to the SSP on how to continue call processing.

     1.63 "Signaling Transfer Point" or "STP" means a specialized switch that 
provides SS7 network access and performs SS7 message routing and screening.

     1.64 "Switched Access Detail Usage Data" means a category 1101XX record as 
defined in the EMR Bellcore Practice BR-010-200-010.

     1.65 "Switched Access Summary Usage Data" means a category 1150XX record 
as defined in the EMR Bellcore Practice BR-010-200-010.



<PAGE>
 
     1.66 "Switched Exchange Access Service" means the offering of transmission 
and switching services for the purpose of the origination or termination of Toll
Traffic.  Switched Exchange Access Services include but may not be limited to: 
Feature Group A, Feature Group B, Feature Group D, 700 access, 800 access, 888 
access, and 900 access.
     
     1.67 "Synchronous Optical Network" or "SONET" means an optical interface 
standard that allows inter-networking of transmission products from multiple 
vendors.  The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are direct 
multiples of the base rate, up to 13.22 Gpbs.

     1.68 "Tariff" means any applicable federal or state tariff of a Party, or 
standard agreement or other document that sets forth the generally available 
terms and conditions under which a Party offers a particular service, facility, 
or arrangement.

     1.69 "Technically Feasible Point" is As Described in the Act.

     1.70 "Telecommunications" is As Defined in the Act.

     1.71 "Telecommunications Act" means the Telecommunication Act of 1996 and 
any rules and regulations promulgated thereunder.

     1.72 "Telecommunications Carrier" is  As Defined in the Act.

     1.73 "Telecommunications Service" is As Defined in the Act.

     1.74 "Telephone Exchange Services," sometimes also referred to as "Exchange
Service," is As Defined in the Act. Telephone Exchange Service generally 
provides the Customer with a telephonic connection to, and a unique telephone 
number address on, the public switched telecommunications network, and 
enables such Customer to place or receive calls to all other stations on the 
public switched telecommunications network.

     1.75 "Toll Traffic" means traffic that is originated by a Customer of one 
Party on that Party's network and terminates to a Customer of the other Party 
on that Party's network and is not Local Traffic or Ancillary Traffic.  Toll 
Traffic may be either "IntraLATA Toll Traffic" or "InterLATA Toll Traffic," 
depending on whether the originating and terminating points are within the same 
LATA.

     1.76 "Transit Traffic" means any traffic that originates from or terminates
at MFS's network, "transits" BA's network substantially unchanged, and 
terminates to or originates from a third carrier's network, as the case may be. 
"Transit Traffic Service" provides MFS with the ability to use its connection to
a BA Access Tandem Switch for the delivery of calls which originate or 
terminate with MFS and terminate to or originate from a carrier other than
BA, such as another CLEC, a LEC other than BA, or a wireless carrier.  In 
these cases, neither the originating nor terminating Customer is a Customer 
of BA.  This service is provided through BA's Access Tandem

<PAGE>
 
Switches.  "Transit Traffic" and "Transit Traffic Service" do not include or 
apply to traffic that is subject to an effective Meet-Point Billing arrangement.

     1.77 "Trunk Side" means a Central Office Switch connection that is capable 
of, and has been programmed to treat the circuit as, connecting to another 
switching entity (e.g. another carrier's network).  Trunk Side connections offer
those transmission and signaling features appropriate for the connection of 
switching entities.

     1.78 "Unbundled Local Loop Element" or "ULL" means a transmission path that
extends from a Main Distribution Frame, DSX-panel, or functionally comparable 
piece of equipment in the Customer's serving End Office to the Rate Demarcation 
Point (or network interface device (NID) if installed) in or at a Customer's 
premises.  The actual loop transmission facilities used to provide an ULL may 
utilize any of several technologies.

     1.79 "Verification with Call Interruption" or "VCI" means a service that 
may be requested and provided when Line Statue Verification has determined that 
a line is busy due to an ongoing call.  VCI is an operator interruption of that 
ongoing call to inform the called party that a calling party is seeking to 
complete his or her call to the called party.

     1.80 "Voice Grade" means either an analog signal of 300 to 3000 Hz or a 
digital signal of 56/64 kilobits per second.  When referring to digital voice 
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.81 "Wire Center" means a building or portion thereof in which a Party has
the exclusive right of occupancy and which serves as a Routing Point for 
Switched Exchange Access Service.


2.0  INTERPRETATION AND CONSTRUCTION.

     2.1  All references to Sections, Exhibits and Schedules shall be deemed to 
be references to Sections of, and Exhibits and Schedules to, this Agreement 
unless the context shall otherwise require.  The headings used in this Agreement
are inserted for convenience of reference only and are not intended to be a 
part of or to affect the meaning of this Agreement.  Unless the context shall 
otherwise require, any reference to any agreement, other instrument (including 
BA or other third party offerings, guides or practices), statute, regulation, 
rule or tariff is to such agreement, instrument, statue, regulation, or rule or 
tariff as amended and supplemented from time to time (and, in the case of a 
statute, regulation, rule or tariff, to any successor provision).

     2.2  Subject to the terms set forth in Section 20, each Party hereby 
incorporates by reference those provisions of its tariff that govern the 
provision of any of the services or facilities provided hereunder.  If any 
provision of this Agreement and an applicable tariff cannot be reasonably 
construed or interpreted to avoid conflict, the Parties agree to negotiate in 
good faith to reconcile and resolve such conflict.  If any provision contained 
in this main body of the Agreement and any Exhibit hereto cannot be reasonable 
construed or interpreted to avoid conflict, the
<PAGE>
 
provision contained in this main body of the Agreement shall prevail. The fact 
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for 
finding, a conflict for purposes of this Section 2.

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1  Subject to the terms and conditions of this Agreement, each Party 
shall exercise its best efforts to adhere to the Interconnection Activation
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to
provide fully operational service predominantly over its own Telephone Exchange
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes
of this Agreement, MFS's service in Virginia shall be considered provided
"predominantly over its own Telephone Exchange Service facilities" if MFS uses
its own Central Office Switch(es) (as opposed to resale of another carrier's
Telephone Exchange Service or Ports) to serve the majority of its Telephone
Exchange Service Customers, its own interoffice transport facilities for the
majority of its interoffice transport needs, and its own local loops (or
functional equivalent), in addition to resale of other carriers' Telephone
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2  Schedule 3.0 may be revised and supplemented from time to time upon 
the mutual agreement of the Parties to reflect the intention of the Parties to 
interconnect in additional LATAs pursuant to subsection 4.4 by attaching one or 
more supplementary schedules to Schedule 3.0. The Parties stipulate and agree 
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act, and the requirements of
the Competitive Checklist, under Section 271 of the Act. MFS represents that it 
is, or intends to become, a provider of Telephone Exchange Service to 
residential and business subscribers offered exclusively over its own Telephone 
Exchange Service facilities or predominantly over its own Telephone Exchange 
Service facilities in combination with the resale of the Telecommunications 
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local 
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit 
Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to the terms
and conditions of this Agreement, Interconnection of the Parties facilities and 
equipment for the transmission and routing of Local Traffic and Toll Traffic 
pursuant to this Section 4 shall be established on or before the corresponding 
"Interconnection Activation Date" shown for each such LATA within Virginia on 
Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and supplemented
from time to time upon the mutual agreement of the Parties to reflect 
Interconnection in additional LATAs
                                                
<PAGE>
 
in Virginia pursuant to subsection 4.4 by attaching one or more supplementary 
addenda to such Schedules.

     4.1  SCOPE

          4.1.1  Section 4 describes the architecture for Interconnection of the
Parties' facilities and equipment over which the Parties shall configure the 
following separate and distinct trunk groups:

          Traffic Exchange Trunks for the transmission and routing of 
          -----------------------
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251(c)(2) of the Act, in accordance with Section 5 below;

          Access Toll Connecting Trunks for the transmission and routing of 
          -----------------------------
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Access Service via
          a BA Access Tandem, pursuant to Section 251(c)(2) of the Act, in
          accordance with Section 6 below;

          Information Services Trunks for the transmission and routing of 
          ---------------------------
          terminating Information Services Traffic in accordance with Section 7 
          below;

          LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
          --------------
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating 
          ---------------     
          E911/911 traffic, in accordance with Section 7 below;

          Directory Assistance Trunks for the transmission and routing of 
          ---------------------------
          terminating directory assistance traffic, in accordance with
          subsection 19.4 below; and

          Operator services (call completion) Trunks for the transmission and 
          ------------------------------------------
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2  The SONET interconnection arrangement described in subsection 
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA 
Toll Traffic until such time as the Parties have agreed to appropriate 
compensation arrangements relating to the exchange of other types of traffic 
over such system, and (ii) subject to the Parties' reaching agreement on an 
appropriate compensation arrangement in the event either Party will be providing
or utilizing (in terms of minutes of use) significantly more than one-half of
the SONET facility. Unless otherwise agreed to by the Parties, the SONET system
described herein shall not be used to exchange InterLATA Toll Traffic. Until the
SONET system has been established by the Parties in accordance with subsection
4.3 and this subsection 4.1.2, the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
(IntraLATA and InterLATA) Traffic.
<PAGE>
 
          4.1.3  To the extent required by Section 251 of the Act, the Parties 
represent that the arrangements provided in susbsections 4.2 and 4.3 of this 
Agreement provide for Interconnection to each other's networks at any 
technically feasible point. For the purposes of this Agreement, the Parties 
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a Local
Serving Wire Center and/or other points as specified herein, and, in the case 
of MFS, at a node or Central Office and/or other points as specified herein
(collectively, the "Interconnection Points" or "IPs").

          4.1.4  The Parties shall establish physical interconnection points at
the available IPs at the locations designated in Schedule 4.0. The mutually
agreed-upon IPs on the MFS network at which MFS will provide transport and 
termination of traffic shall be designated as the MFS Interconnection Points 
("M-IPs"); the mutually agreed-upon IPs on the BA network shall be designated as
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of 
charging for the transport of traffic from the BA-IP to the M-IP in any given 
LATA, the M-IP shall be no further than an entrance facility away from the BA-IP
in such LATA. The Parties may by mutual agreement establish additional 
interconnection points at any technically feasible points consistent with the 
Act.

     4.2  PHYSICAL ARCHITECTURE. In each LATA identified on Schedule 4.0, MFS 
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous 
Optical Network ("SONET") transmission system by which they shall interconnect 
their networks pursuant to the joint network reconfiguration and grooming plan 
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the 
following specifications:

          4.2.1  The SONET system shall be used to deliver appropriate traffic
to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2  The SONET transmission system in each LATA shall be configured 
substantially as illustrated in Schedule 4.2 and pursuant to the Joint Grooming 
Plan, or as otherwise mutually agreed. The Parties shall agree upon which Party 
or Parties shall be responsible for procuring, installing, and maintaining the 
agreed-upon Optical Line Terminating Multiplexor ("OLTM") equipment, fiber optic
facilities and other equipment pursuant to the Joint Grooming Plan, as 
illustrated in that Schedule.

          4.2.3  The physical interface of MFS's and BA's facilities necessary
to effect SONET transmission shall be at the optical level via a Mid-Span Meet
or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1  The Parties agree to provide initial interconnection 
arrangements utilizing electrical handoffs, substantially as illustrated in
Schedule 4.3 for a period of no more than

<PAGE>
 
eighteen (18) months after the later of the Effective Date and the LATA Start 
Date set forth for the LATA in Schedule 3.0; provided, however, that such 
initial interconnection arrangements shall continue until (i) facilities 
suitable for the SONET arrangements described in subsection 4.2 are established 
by each of the Parties in its own sole discretion in the LATA at the mutually 
agreed-upon SONET meet points and made available, and (ii) the Parties have 
agreed upon fully compatible OLTM equipment for use with such facilities.

          4.3.2  The Parties agree to utilize the M-IP and BA-IP in each LATA as
designated in Schedule 4.0 as the points from which each Party will provide the 
transport and termination of traffic.

          4.3.3  MFS shall provide its own facilities for the delivery of 
traffic to a collocation arrangement established at the BA-IP pursuant to 
Section 13. Bell Atlantic shall provide transport and termination of the traffic
beyond the BA-IP.

          4.3.4  BA shall purchase an MFS entrance facility (and any necessary 
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the M-
IP. Alternatively, BA may choose to provide its own facilities to a collocation
arrangement established at the M-IP pursuant to Section 13. MFS shall provide
transport and termination of the traffic beyond the M-IP.

          4.3.5  Under this initial architecture described in this subsection 
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5 
below and pursuant to the other Party's Switched Exchange Access Service 
tariffs. The other Party's Switched Exchange Access Service rates shall apply to
such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk 
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.

     4.4       INTERCONNECTION IN ADDITIONAL LATAs

          4.4.1  If MFS determines to offer Telephone Exchange Services in any 
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange 
Services, MFS shall provide written notice to BA of the need to establish 
Interconnection in such LATA pursuant to this Agreement.

          4.4.2  The notice provided in subsection 4.4.1 shall include (i) the 
initial Routing Point MFS has designated in the new LATA; (ii) MFS's requested 
Interconnection Activation Date (and related milestone dates in accordance with 
the format in Schedule 3.0); and (iii) a non-binding forecast of MFS's trunking 
requirements.

          4.4.3  Unless otherwise agreed to by the Parties, the Parties shall 
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local 
Serving Wire Center that houses an Access Tandem Office within the LATA nearest 
to the M-IP (as measured in airline miles

                                      14
<PAGE>
 
utilizing the V&H coordinates method) as the BA-IP in that LATA, provided that, 
for the purpose of charging for the transport of traffic from the BA-IP to the 
M-IP, the M-IP shall be no further than an entrance facility away from the 
BA-IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to
reflect the schedule applicable to each new LATA requested by MFS; provided,
however, that unless agreed by the Parties, the Interconnection Activation Date
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten
(10) business days of BA's receipt of MFS's notice, BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party
shall make available Interconnection Points and facilities for routing of
traffic from those Interconnection Points as designated in Schedule 4.5. Any
additional traffic that is not covered in Schedule 4.5 shall be subject to
separate negotiations between the Parties, except that (i) either Party may
deliver traffic of any type or character to the other Party for termination as
long as the delivering Party pays the receiving Party's then current Switched
Exchange Access rates for such traffic, and (ii) upon a bona fide request from
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an
agreement covering the exchange of such traffic.

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO 
SECTION 251(C)(2)   

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups
(the "Traffic Exchange Trunks") to be effected over the Interconnections
specified in Section 4.0 for the transmission and routing of Local Traffic and
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-1 level or higher
for exchange of Local and Toll Traffic. Higher speed connections shall be made,
when and where available, in accordance with the Joint Grooming Plan prescribed
in Section 10. Ancillary Traffic trunk groups made below a DS-1 level, as may be
agreed to by the Parties.

          5.2.2  Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

          5.3.1  For purposes of routing MFS traffic to BA, the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own or
<PAGE>
 
other carriers' traffic. For purposes of routing BA traffic to MFS, the 
subtending arrangements between MFS Access Tandem Switches (or functional 
equivalent) and MFS End Office Switches (or functional equivalent) shall be the 
same as the Access Tandem/End Office subtending arrangements (or functional 
equivalent) which MFS maintains for the routing of its own or other carriers' 
traffic.

     5.4  SIGNALING

     Each Party will provide the other Party with access to its databases and 
associated signaling necessary for the routing and completion of the other 
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5  GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6  MEASUREMENT AND BILLING

          5.6.1  For billing purposes, each Party shall pass Calling Party
Number ("CPN") information on each call carried over the Traffic Exchange
Trunks, wherever technically feasible. At such time as either Party has the
ability, as the Party receiving the traffic, to use such CPN information to
classify on an automated basis traffic delivered by the other Party as either
Local Traffic or Toll Traffic, such receiving Party shall bill the originating
Party the Local Traffic termination rates, Intrastate Exchange Access rates, or
Interstate Exchange Access rates applicable to each minute of Traffic for which
CPN is passed, as provided in Exhibit A and applicable Tariffs.

          5.6.2  If, under the circumstances set forth in subsection 5.6.1. it
is not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party the
Local Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, for which CPN is passed. For the remaining up
to ten percent (10%) of calls without CPN information, the receiving Party shall
bill the originating Party for such traffic as Local Traffic termination rates,
Intrastate Exchange Access rates, or Interstate Exchange Access rates applicable
to each minute of traffic, as provided in Exhibit A and applicable Tariffs, in
direct proportion to the minutes of use of calls passed with CPN information.

          5.6.3  If it is not technically feasible for the originating Party to
pass CPN on more than ten percent (10%) of calls, or if the receiving Party
lacks the ability to use CPN information to classify on an automated basis
traffic delivered by the other Party as either Local Traffic or Toll Traffic,
and the originating Party chooses to combine Local and Toll Traffic on the same
trunk group, it will supply an auditable Percent Local Use ("PLU") report
quarterly, based on the previous three months' traffic, and applicable to the
following three months. If the originating
<PAGE>
 
Party also chooses to combine Interstate and Intrastate Toll Traffic on the same
trunk group, it will supply an auditable Percent Interstate Use ("PIU") report 
quarterly, based on the previous three months' terminating traffic, and 
applicable to the following three months. In lieu of the foregoing PLU and/or 
PIU reports, the Parties may agree to provide and accept reasonable surrogate 
measures for an agreed-upon interim period.

          5.6.4  Measurement of billing minutes for purposes of determining
terminating compensation shall be in conversation seconds.

     5.7  RECIPROCAL COMPENSATION ARRANGEMENTS--SECTION 251(B)(5).

     Reciprocal Compensation arrangements address the transport and termination
of Local Traffic. BA's delivery of Traffic to MFS that originated with a third
carrier is addressed in subsection 7.3. Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and termination of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

          5.7.1  Nothing in this Agreement shall be construed to limit either
Party's ability to designate the areas within which that Party's Customers may
make calls which that Party rates as "local" in its Customer Tariffs.

          5.7.2  The Parties shall compensate each other for transport and
termination of Local Traffic in an equal and symmetrical manner at the rates
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if
not set forth therein, in the applicable Tariff(s) of the terminating Party, as
the case may be. These rates are to be applied at the M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges,
including port or transport charges, shall apply for the termination of Local
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A.
When Local Traffic is terminated over the same trunks as Toll Traffic, any port
or transport or other applicable access charges related to the Toll Traffic
shall be prorated to be applied only to the Toll Traffic.

          5.7.3  The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs.

          5.7.4  Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5.

                                      17
<PAGE>
 
          5.7.5  The designation of Traffic as Local or Toll for purposes of
compensation shall be based on the actual originating and terminating points of
the complete end-to-end call, regardless of the carrier(s) involved in carrying
any segment of the call.

          5.7.6  Each Party reserves the right to measure and audit all Traffic
to ensure that proper rates are being applied appropriately. Each Party agrees
to provide the necessary Traffic data or permit the other Party's recording
equipment to be installed for sampling purposes in conjunction with any such
audit.

          5.7.7  The Parties will engage in settlements of alternate-billed
calls (e.g. collect, calling card, and third-party billed calls) originated or
authorized by their respective Customers in Virginia in accordance with the
terms of an appropriate billing services agreement for intraLATA intrastate
alternate-billed calls or such other arrangement as may be agreed to by the
Parties.

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2)

     6.1  SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over
the Interconnections specified in Section 4 for the transmission and routing of
traffic between MFS Telephone Exchange Service Customers and Interexchange
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

          6.2.1  MFS shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from MFS's Customers.

          6.2.2  Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access to allow MFS's Customers to connect
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

          6.2.3  The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch MFS utilizes to provide Telephone Exchange
Service and Switched Exchange Access in a given LATA to an Access Tandem BA
utilizes to provide Exchange Access in such LATA.

          6.2.4  The Parties shall jointly determine which BA Access Tandem(s)
will be subtended by each MFS End Office Switch. MFS's End Office switch shall
subtend the BA Access Tandem that would have served the same rate center on BA's
network. Alternative configurations will be discussed as part of the Joint Plan.

                                      18
<PAGE>
 
     6.3  MEET-POINT BILLING ARRANGEMENTS

          6.3.1  MFS and BA will establish Meet-Point Billing arrangements in 
order to provide a common transport option to Switched Access Services Customers
via an Access Tandem Switch in accordance with the Meet-Point Billing guidelines
contained in the OBF's MECAB and MECOD documents, except as modified herein, and
BA's Virginia Tariff Number 217, Section 2.4.8. The arrangements described in 
this Section 6 are intended to be used to provide Switched Exchange Access 
Service that originates and/or terminates on a Telephone Exchange Service that 
is provided by either Party, where the transport component of the Switched 
Exchange Access Service is routed through a Tandem Switch that is provided by 
BA.

          6.3.2  In each LATA, the Parties shall establish MPB arrangements 
between the applicable Rating Point/BA Local Serving Wire Center combinations.

          6.3.3  Interconnection for the MPB arrangement shall occur at the 
BA-IP in the LATA, unless otherwise agreed to by the Parties.

          6.3.4. MFS and BA will use reasonable efforts, individually and 
collectively, to maintain provisions in their respective state access tariffs, 
and/or provisions within the National Exchange Carrier Association ("NECA") 
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

          6.3.5  Each Party shall implement the "Multiple Bill/Single Tariff" or
"Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an IXC
for the portion of the jointly provided telecommunications service provided by
that Party.

          6.3.6  The rate elements to be billed by each Party are as set forth
in Schedule 6.3. The actual rate values for each Party's affected access service
rate element shall be the rates contained in that Party's own effective federal
and state access tariffs, or other document that contains the terms under which
that Party's access services are offered. The MPB billing percentages for each
Rating Point/BA Local Serving Wire Center combination shall be calculated in
accordance with the formula set forth in subsection 6.3.16 below.

          6.3.7  Each Party shall provide the other Party with the billing
name, billing address, and Carrier Identification Code ("CIC") of the IXC, and
identification of the IXC's Local Serving Wire Center in order to comply with
the MPB notification process as outlined in the MECAB document via facsimile or
such other media as the Parties may agree to.

          6.3.8  BA shall provide MFS with the Switched Access Detail Usage
Data (category 1101XX records) on magnetic tape or via such other media as the
Parties may agree to, no later than ten (10) business days after the date the
usage occurred.

          6.3.9  MFS shall provide BA with the Switched Access Summary Usage
Data (category 1150XX records) on magnetic tape or via such other media as the
Parties may agree, no
                     
                                      19

<PAGE>
 
later than ten (10) business days after the date of its rendering of the bill to
the relevant IXC, which bill shall be rendered no less frequently than monthly.

          6.3.10  Each Party shall coordinate and exchange the billing account 
reference ("BAR") and billing account cross reference ("BACR") numbers or 
Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each Party 
shall notify the other if the level of billing or other BAR/BACR elements 
change, resulting in a new BAR/BACR number, or if the OCN changes.

          6.3.11. Errors may be discovered by MFS, the IXC or BA. Each Party 
agrees to provide the other Party with notification of any errors it discovers 
within two (2) business days of the date of such discovery. In the event of a 
loss of data, both Parties shall cooperate to reconstruct the loss data and, if 
such reconstruction is not possible, shall accept a reasonable estimate of the 
lost data based upon prior usage data.

          6.3.12  Either Party may request a review or audit of the various 
components of access recording up to a maximum of two (2) audits per calendar 
year. All costs associated with each review and audit shall be borne by the 
requesting Party. Such review or audit shall be conducted subject to 
confidentiality protection and during regular business hours. A Party may 
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

          6.3.13. Nothing contained in this subsection 6.3. shall create any 
liability for damages, losses, claims, costs, injuries, expenses or other 
liabilities whatsoever on the part of either Party (other than as may be set 
forth in MECAB or in any applicable Tariff).

          6.3.14. The Parties shall not charge one another for the services 
rendered or information provided pursuant to this subsection 6.3.

          6.3.15  MPB will apply for all traffic bearing the 500, 900, 800/888 
(to the extent provided by an IXC) or any other non-geographic NPA which may be 
likewise designated for such traffic in the future.

          6.3.16  In the event MFS determines to offer Telephone Exchange 
Services in another LATA in which BA operates an Access Tandem Switch, BA shall 
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for 
the BA End Offices in the area where the MFS Rating Point(s) associated with the
NPA-NXX(s) to/from which the Switched Exchange Access Services are homed. The 
MPB billing percentages for each new Rating Point/BA Local Serving Wire Center 
combination shall be calculated according to the following formula:

                           a/(a + b) = MFS Billing Percentage
                                         and
                           b/(a + b) = BA Billing Percentage

                  where:
                  -----

                                      20
<PAGE>
 
                  a = the airline mileage between the Rating Point and the
               actual point of interconnection for the MPB arrangement; and

                  b = the airline mileage between the BA Local Serving Wire
               Center and the actual point of interconnection for the MPB
               arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange
Services and its calculation of the billing percentages which should apply for
such arrangement, as part of the notice required by subsection 4.4.1 above.
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS
shall confirm the new Rating Point/BA Local Serving Wire Center combination and
billing percentages. Nothing in this subsection 6.3.16 shall be construed to
limit MFS's ability to select to interconnect with BA in additional LATAs by
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

     6.4  800/888 TRAFFIC

     The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

          6.4.1.  When MFS delivers untranslated 800/888 calls to BA for
completion

                  (a)  to an IXC, BA shall:

                       (i)   Provide a MPB record in an industry standard format
                       to MFS; and

                       (ii)  Bill the IXC the appropriate BA query charge 
                       associated with the call.

                  (b)  as an IntraLATA call to BA or another LEC in the LATA, 
BA shall

                       (i)   Provide a copy record in an industry standard
                       format to MFS;

                       (ii)  Bill MFS the appropriate BA query charge associated
                       with the call; and

                       (iii) Submit the call records to ITORP for payment by BA
                       or the LEC that is the 800/888 service provider of MFS's
                       and any intermediate LEC's Tariffed Exchange Access
                       charges and query charges.

                                      21
<PAGE>
 
          6.4.2  When BA delivers 800/888 calls originated by BA's or another 
LEC's Customers to MFS for completion

                 (a)  to MFS in its capacity as an IXC, BA shall:

                      (i)  Bill MFS to appropriate BA query charge associated 
                      with the call; and

                      (ii) Bill MFS the appropriate FGD Exchange Access charges 
                      associated with the call.

                 (b)  as an IntraLATA call to MFS in its capacity as a LEC,

                      (i)  BA shall submit the appropriate call records to ITORP
                      for payment by MFS of BA's (and another LEC's, if
                      appropriate) Tariffed Exchange Access charges; and

                      (ii) MFS shall pay the originating LEC's appropriate query
                      charge associated with the call.

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to MFS-originated Information 
Services Traffic directed to an information services platform connected to BA's 
network. At such time as MFS connects Information Services platforms to its 
network, the Parties shall agree upon a suitable arrangement for BA-originated 
Information Services Traffic.

          7.1.1  MFS shall route Information Services Traffic that originates on
its own network to the appropriate information services platform(s) connected to
BA's network. MFS will establish a dedicated trunk group to the BA information 
services serving switch. This trunk group will be utilized to allow MFS to route
information service traffic originated on its network to BA.

          7.1.2  MFS shall provide an electronic file transfer or monthly 
magnetic tape containing recorded call detail information to BA.

          7.1.3  BA shall provide to MFS via electronic file transfer or 
magnetic tape or other means as available all necessary information to rate the 
Information Services Traffic to MFS's Customers pursuant to the BA's agreements 
with each information services provider. Information shall be provided in as 
timely a fashion as practical in order to facilitate record review and reflect 
actual prices set by the individual information services providers.

                                      22
<PAGE>
 
          7.1.4  MFS shall bill and collect such information services provider 
charges and remit the amounts collected to BA less:

          (a)    The Information Services Billing and Collection fee set forth
     in Exhibit A; and

          (b)    An uncollectibles reserve calculated based on the
     uncollectibles reserve in BA's billing and collection agreement with the
     applicable information services provider; and

          (c)    Customer adjustments provider by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and 
Customer adjustments to allow BA to pass through the adjustments to the 
information services provider, and BA shall pass through such adjustments. 
However, if the information services provider disputes such adjustments and 
refuses to accept such adjustments, MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputed adjustments shall be solely
between MFS and the information services provider.

          7.1.5  Nothing in this Agreement shall restrict either Party from 
offering to its Telephone Exchange Service Customers the ability to block the 
completion of Information Service Traffic.

          7.1.6  The Parties may agree to separate arrangements for the billing 
and compensation of variable rated (e.g. 970, 540) information services.

          7.1.7  The Information Services Traffic addressed herein does not 
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1  Each Party shall offer LSV and VCI services to enable its 
Customers to verify and/or interrupt calls of the other Party's Customers. In 
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party 
(Party A) and the responding Party (Party B) shall perform in accordance with 
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to 
be agreed upon between the Parties.

          7.2.2  The Party B operator shall only verify the status of the line 
(LSV) or interrupt the line to inform the called party that there is a call 
waiting. The Party B operator will not complete the telephone call of the 
Customer initiating the LSV/VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable 
charges apply whether or not the called party releases the line.
<PAGE>
 
          7.2.3  Each Party's operator bureau shall accept LSV and VCI inquiries
from the operator bureau of the other Party in order to allow transparent 
provision of LSV/VCI Traffic between the Paries' networks.

          7.2.4  Each Party shall route LSV/VCI Traffic inquiries over separate
direct trunks (and not the Local/IntraLATA/InterLATA Trucks) established between
the Parties' respective operator bureaus. Each Party shall offer interconnection
for LSV/VCI traffic at its Local Serving Wire Center, operator services Tandem
Office subtended by such Local Serving Wire Center, or other mutually agreed
point in the LATA. Separate LSV/VCI trunks delivered at the Local Serving Wire
Center will be directed to the operator services Tandem Office designated by
Party B. Unless otherwise mutually agreed, the Parties shall configure LSV/VCI
trunks over the Interconnection architectures in accordance with the terms of
Section 4, consistent with the Joint Grooming Plan. Party A shall outpulse the
appropriate NPA, ATC Code, and Routing Code (operator code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a 
reciprocal local traffic exchange arrangement (either via written agreement or
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as
quickly as commercially reasonable following the Effective Date and to provide
copies thereof to BA, but continues to utilize BA's Transit Service for the
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC,
MFS shall, in addition to paying the rate set forth in Exhibit A for said
Transit Service, pay BA any charges or costs such terminating third party
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred
                                       ----
by BA in delivering or terminating such Traffic and/or resulting from MFS's
failure to secure said reciprocal local traffic exchange arrangement. BA will,
upon request, provide MFS with all reasonable cooperation and assistance in
obtaining such arrangements. The Parties agree to work cooperatively in
appropriate industry fora to promote the adoption of reasonable industry
guidelines relating to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will
deliver each call to each involved network with CCS and the appropriate 
Transactional Capabilities Application Part ("TCAP") message to facilitate full 
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and 
exchange records between the Parties and with the terminating carrier to
facilitate the billing process to the originating network.

                                      24





<PAGE>
 
          7.3.4  Transit Traffic shall be routed over the Traffic Exchange 
Trunks described in Section 5 above.

     7.4. 911/E911 ARRANGEMENTS

          7.4.1  MFS will interconnect to the BA 911/E911 selective routers or
911 Tandem Offices, where available, which serve the areas in which MFS 
provides Telephone Exchange Services, for the provision of 911/E911 services and
for access to all subtending Public Safety Answering Points ("PSAP"). In such
situations, BA will provide MFS with the appropriate CLLI codes and 
specifications of the Tandem Office serving area. In areas where E911 is not
available, MFS and BA will negotiate arrangements to connect MFS to the 911
service.

          7.4.2  Path and route diverse interconnections for 911/E911 shall be
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed, 
and as required by law or regulation.

          7.4.3  Upon request, BA will provide MFS with the following:

          (a)    an electronic interface, when available, through which MFS 
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911 
     information such as name, address and telephone number in writing for
     BA's entry into the 911 database system. Any 911-related data exchanged
     between the Parties shall conform to the National Emergency Number
     Association standards;

          (b))    a file containing the Master Street Address Guide ("MSAG"),
     as may be updated from time to time, for the exchanges or communities 
     specified;

          (c)    a return of any MFS E911 data entry files containing errors,
     so that MFS may ensure the accuracy of the Customer records; and

          (d)    PSAP 911 Tandem information.

          7.4.4  In cases where a Customer of one Party elects to discontinue
its service and become the Customer of the other Party ("Party B") but desires
to retain its original telephone number pursuant to an INP or PNP arrangement,
Party B will outpulse the telephone number to which the call has been forwarded
(i.e. the Customer's ANI) to 911 Tandem Office. Party B will also provide the 
 - -
911 database with both the forwarded number and the directory number, as well
as the appropriate address information of the Customer.

          7.4.5  BA and MFS will use their best efforts to facilitate the
prompt, robust, reliable and efficient interconnection of MFS systems to the
911/E911 platforms.

                               25              
<PAGE>
 
          7.4.6  BA and MFS will work cooperatively to arrange meetings with
PSAPs to answer any technical questions the PSAPs, or county or municipal
coordinators may have regarding the 911/E911 arrangements. BA shall assist MFS
in identifying the appropriate person in each municipality for the purpose of
obtaining the ten-digit subscriber number of each PSAP.

          7.4.7  The Parties acknowledge that the provision of INP, until PNP 
with full 911 compatability is available, creates a special need to have the 
Automatic Location Identification ("ALI") screen reflect two number: the "old" 
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification 
("TCI") of the company that provides service to the calling line as part of ALI 
display. Until such time as TCI is operational, however, BA and MFS agree to 
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8  MFS will compensate BA for connections to its 911/E911 pursuant
to Exhibit A.

          7.4.9  MFS will comply with all applicable rules and regulations 
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY   Ancillary Traffic that may be terminated
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise 
adversely affect in any manner either Party's right to employ or to request and 
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code 
Assignment Guidelines, as may be amended from time to time, or to establish, by 
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX 
codes. Until such time as number administration is provided by a third party, BA
shall provide MFS access to telephone numbers by assigning NXX codes to MFS in 
accordance with such Assignment Guidelines.

     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing
Guide ("LERG") in order to recognize and route traffic to the other Party's
assigned NXX codes at all times. Neither Party shall impose any fees or charges
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, MFS shall 
adopt the Rate Center Areas and Rate Center Points that the Commission has 
approved for BA in all areas where BA and 

                                      26
<PAGE>
 
MFS service areas overlap, and MFS shall assign whole NPA-NXX codes to each Rate
Center unless the LEC industry adopts alternative methods of utilizing NXXs in
the manner adopted by the NANP.

     8.4  MFS will also designate a Routing Point for each assigned NXX code. 
MFS shall designate one location for each Rate Center Area as the Routing Point 
for the NPA-NXXs associated with that Area, and such Routing Point shall be 
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in 
this Agreement is intended to, and nothing in this Agreement shall be construed 
to, in any way constrain MFS's choices regarding the size of the local calling 
area(s) that MFS may establish for its Customers, which local calling areas may 
be larger than, smaller than, or identical to, BA's local calling areas.

9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance 
contact numbers, network information, information required to comply with law 
enforcement and other security agencies of the Government) to achieve this 
desired reliability. In addition, the Parties will work cooperatively to apply 
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that 
may be agreed to between the Parties and to employ characteristics and methods 
of operation that will not interfere with or impair the service or any 
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of 
operation used by Party B will or may interfere with or impair its provision of 
services, Party A shall have the right to discontinue Interconnection subject, 
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days' prior written 
notice of interference or impairment or potential interference or impairment 
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice 
provided to Party B under (a) above to the appropriate federal and/or state 
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall 
not be required in emergencies and Party A may immediately discontinue 
Interconnection if reasonably necessary

                                      27
<PAGE>
 
to meet its obligations. In such case, however, Party A shall use all reasonable
means to notify Party B and the appropriate federal and/or state regulatory 
bodies.

          9.3.4 Upon correction of the interference or impairment, Party A will 
promptly renew the Interconnection. During such period of discontinuance, there 
will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE 

          9.4.1 The Interconnection provided hereunder may be discontinued by 
either Party upon thirty (30) days written notice to the other for repeated or 
willful violation of and/or a refusal to comply with this Agreement. The Party 
discontinuing will notify the appropriate federal and/or state regulatory bodies
concurrently with the notice to the other Party of the prospective 
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or 
service being provided by a Party hereunder, the providing Party will follow 
procedures for isolating and clearing the outage or trouble that are no less 
favorable than those that apply to comparable arrangements, facilities, or 
services being provided by the providing Party to any other carrier whose 
network is connected to that of the providing Party. MFS and BA may agree to 
modify those procedures from time to time based on their experience with 
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES -- SECTION 251(C)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN.  On or before 
December 1, 1996, unless the Parties agree to a different date, MFS and BA shall
jointly develop a grooming plan (the "Joint Plan") which shall define and 
detail, inter alia,
        ----- ----

          (a)  modifications to the agreement on physical architecture
     consistent with the guidelines defined in Section 4;

          (b)  standards to ensure that Interconnection trunk groups experience
     a grade of service, availability and quality which is comparable to that
     achieved on interoffice trunks within BA's network and in accord with all
     appropriate relevant industry-accepted

                                      28
 
<PAGE>
 
     quality, reliability and availability standards. Trunks provided by either
     Party for Interconnection services will be engineered using a design
     blocking objective of B.01;

          (c)  the respective duties and responsibilities of the Parties with 
     respect to the administration and maintenance of the trunk groups,
     including, but not limited to, standards and procedures for notification
     and discoveries of trunk disconnects;

          (d)  disaster recovery provision escalations;

          (e)  migration from one-way to two-way Interconnection Trunks upon 
     mutual agreement of the Parties;

          (f)  actual meet point locations on the SONET system; and

          (g)  such other matters as the Parties may agree.

     10.2 INSTALLATION, MAINTENANCE, TESTING AND REPAIR. BA's standard intervals
for Feature Group D Switched Exchange Access Services will be used for 
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of its facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its
inability to do so and will negotiate such intervals in good faith. The Parties
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than
those applicable to comparable arrangements, facilities, or services being
provided by such Party to any other carrier whose network is connected to that
of the providing Party.

     10.3 FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING. Within sixty (60) 
days of executing this Agreement, MFS shall provide BA a one (1) year traffic 
forecast. This initial forecast will provide the amount of traffic to be 
delivered to each of BA's End Offices affected by the exchange of traffic. The 
forecast shall be updated and provided to BA on a quarterly basis, and include 
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator 
services, 911, etc.), code (identifies truck group), A location/Z location (CLLI
codes), interface type (e.g., DS1), and trunks in service each year 
(cumulative).

          10.3.1  Initial Forecasts/Trucking Requirements. Because BA's trunking
                  ---------------------------------------
requirements will, at least during an initial period, be dependent on the
customer segments and service segments within customer segments to whom MFS
decides to market its services, BA will be largely dependent on MFS to provide
accurate trunk forecasts for both inbound (from BA) and outbound (from MFS)
traffic. BA will, as an initial matter and upon request, provide the same number
of trunks to terminate local traffic to MFS as MFS provides to terminate local
traffic to BA, unless MFS expressly identifies particular situations that are
expected to produce traffic that is substantially skewed in either the inbound
or outbound direction, in which case BA will provide the number of trucks MFS
suggests. Upon the establishment of any new set of trunks for traffic from BA to
MFS, BA will monitor traffic for ninety (90) days, and will, as

                                      29

<PAGE>
 
necessary at the end of that period, either augment trunks or disconnect trunks,
based on the application of reasonable engineering criteria to the actual 
traffic volume experienced. If, after such 90-day period, BA has determined that
the trunks are not warranted by actual traffic volumes, then, on ten (10) days'
written notice, BA may hold MFS financially responsible for such trunks 
retroactive to the start of the 90-day period until such time as they are 
justified by actual traffic volumes, based on the application of reasonable 
engineering criteria. To the extent that BA requires MFS to install trunks for 
delivery of traffic to BA, MFS may apply the same procedures with respect to 
BA's trunking requirements.

11.0 UNBUNDLED ACCESS - SECTION 251(C)(3).

     To the extent required of each Party by Section 251 of the Act, each Party
shall offer to the other Party nondiscriminatory access to Network Elements on
an unbundled basis at any technically feasible point. BA shall unbundle and
separately price and offer Network Elements such that MFS will be able to lease
and interconnect to whichever of the Network Elements MFS requires, and to
combine the BA-provided elements with any facilities and services that MFS may
itself provide, except that MFS shall not recombine Network Elements purchased
from BA for use as a substitute for the purchase at wholesale rates of
Telecommunications Services that BA provides unless otherwise mandated by the
FCC or the Commission or agreed to by BA with other carriers.

     11.1 UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

     Subject to subsection 11.4, BA shall allow MFS to access the following ULL 
types (in addition to those ULLs available under applicable tariffs) unbundled 
from local switching and local transport in accordance with the terms and 
conditions set forth in this subsection 11.1.

          11.1.1    "2-Wire Analog Voice Grace ULL" or "Analog 2W" provides an 
effective 2-wire channel with 2-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals and loop-
start signaling. The service is more fully described in Bell Atlantic TR-72565.
If "Customer-Specified Signaling" is requested, the service will operate with
one of the following signaling types that may be specified when the service is
ordered: loop-start, ground-start, loop-reverse-battery, and no signaling. The
service is more fully described in Bell Atlantic TR-72570.

          11.1.2    "4-Wire Analog Voice Grade ULL" or "Analog 4W" provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The 
service will operate with one of the following signaling types that may be 
specified when the service is ordered: loop-start, ground-start, 
loop-reverse-battery, duplex, and no signaling. The service is more fully 
described in Bell Atlantic TR-72570.

          11.1.3    "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides a 
channel with 2-wire interfaces at each end that is suitable for the transport of
160 kbps digital services using the ISDN 2B1Q line code.

                                      30
<PAGE>
 
          11.1.4 "2-Wire ADSL-Compatible ULL" or "ADSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of digital
signals up to 6Mbps toward the Customer and up to 640 kbps from the Customer. BA
will offer ADSL-Compatible ULLs only when the technology BA uses to provide such
ULLs is compatible with that of MFS. In addition, ADSL-Compatible ULLs will be 
available only where existing copper facilities can meet applicable industry 
standards.

          11.1.5 "2-Wire HDSL-Compatible ULL" or "HDSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of 784
kbps digital signals simultaneously in both directions using the 2B1Q line code.
HDSL compatible ULLs will be available only where existing copper facilities can
meet the specifications.

          11.1.6 "4-Wire HDSL-Compatible ULL" or "HDSL 4W" provides a channel 
with 4-wire interfaces at each end. Each 2-wire channel is suitable for the 
transport of 784 kbps digital signals simultaneously in both directions using 
the 2B1Q line code. HDSL compatible ULLs will be available only where existing 
copper facilities can meet the specifications.

          11.1.7 ULLs will be offered on the terms and conditions specified 
herein and on such other terms in applicable Tariffs that are not inconsistent 
with the terms and conditions set forth herein. BA shall make ULLs available to 
MFS at the rates specified by the Commission, as amended from time to time, 
subject to the provisions of subsection 11.1.8 below.

          11.1.8 BA will make Analog 2-Wire ULLs available for lease by MFS in 
accordance with the schedule set forth in Schedule 3.0. BA will make BRI ISDN 
and Analog 4W ULLs available for lease by MFS by the later of January 1, 1997, 
or the date when the ULL milestone contained in Schedule 3.0 is achieved in the 
LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease by 
MFS as soon as practicable, but in any event no later than six months, after BA 
makes the services using equivalent loop facilities commercially available to 
its own end-user Customers in Virginia. Upon request by either BA or MFS, the 
Parties shall agree upon a reasonable schedule and location for a technical and 
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s) 
may, by mutual agreement, be conducted in any jurisdiction in which affiliates 
of BA and MFS both operate. Upon successful completion of such trial(s), the 
Parties shall agree upon an implementation schedule for the ULL type(s) subject 
to such trial(s), which schedule shall begin no later than ninety (90) days 
after successful completion of such trial(s).

    11.2  PORT TYPES

    BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.

                                      31
<PAGE>
 
     11.3    TRUNK SIDE LOCAL TRANSPORT
     
     BA shall provide MFS local transport from the trunk side of BA's Central
Office Switches using private lines and special access services unbundled from
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

     11.4    LIMITATIONS ON UNBUNDLED ACCESS
     
             11.4.1 Unless otherwise mandated by the FCC or the Commission or 
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under 
applicable tariffs.
     
             11.4.2 BA shall only be required to make available ULLs and Ports
where such ULLs and Ports are available.

             11.4.3 MFS shall access BA's unbundled Network Elements
specifically identified in this Agreement via Collocation in accordance with
Section 13 at the BA Wire Center where those elements exist and each ULL or Port
shall be delivered to MFS's Collocation by means of a Cross Connection.

             11.4.4 BA shall provide MFS access to its Unbundled Local Loops at
each of BA's Wire Centers for loops terminating in that Wire Center. In
addition, if MFS requests one or more ULLs provisioned via Integrated Digital
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA
shall, where available, move the requested ULL(s) to a spare, existing physical
ULL at no additional charge to MFS. If, however, no spare physical ULL is
available, BA shall within three (3) business days of MFS's request notify MFS
of the lack of available facilities. MFS may then at its discretion make a
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the
ULL concentration site point. Alternatively, MFS may choose to avail itself of
BA's Special Construction services, as set forth in Exhibit A, for the
provisioning of such ULL(s). Notwithstanding anything to the contrary in this
Agreement, the provisioning intervals set forth in subsection 11.6 and the
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this
subsection 11.4.4.

             11.4.5 If MFS orders a ULL type and the distance requested on such 
ULL exceeds the transmission characteristics in applicable technical references,
distance extensions may be required and additional rates and charges shall apply
as set forth in Exhibit A or applicable Tariffs.

             11.4.6 BA will exercise all reasonable efforts to ensure that the 
service intervals that apply to ULLs and unbundled Ports are comparable to the 
(i) repair intervals that apply to the bundled dial tone line service, and (ii) 
installation intervals that apply to other BA-coordinated services, except as 
provided in Section 27. Although BA will make commercially

                                      32
<PAGE>
 
reasonable efforts to ensure that ULLs and unbundled ports meet specified or
agreed-upon technical standards, BA makes no warranty that the ULLs or 
unbundled Ports supplied by BA hereunder will be compatible with the services
MFS may offer to its Customers if they are used in a manner not contemplated by
the Parties.

     11.5   AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

            11.5.1 BA shall, upon request of MFS, and to the extent technically 
feasible, provide to MFS access to its Network Elements on an unbundled basis 
for the provision of MFS's Telecommunications Service.  Any request by MFS for
access to an BA Network Element that is not already available shall be treated 
as a Network Element Bona Fide Request.  MFS shall provide BA access to its 
Network Elements as mutually agreed by the Parties or as required by the 
Commission or FCC.

            11.5.2 A Network Element obtained by one Party from the other Party
under this subsection 11.5 may be used in combination with the facilities of the
requesting Party only to provide a Telecommunications Service, including 
obtaining billing and collection, transmission, and routing of the
Telecommunications Service.

            11.5.3 Notwithstanding anything to the contrary in this subsection
11.5, a Party shall not be required to provide a proprietary Network Element to
the other Party under this subsection 11.5 except as required by the Commission 
or FCC.

     11.6   PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs.  These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA
to MFS and from MFS to BA.

            11.6.1 Upon request by MFS, BA will apply the following coordination
procedures to conversions of live Telephone Exchange Services to ULLs.  
Coordinated cutover charges will apply to any such arrangement, only to the 
extent provided by Section A.4.a of Exhibit A.  If MFS elects not to request 
coordinated cutover, BA will process MFS's request in the normal course and 
subject to the normal installation intervals.

            11.6.2 MFS shall request ULLs from BA by delivering to BA a valid 
electronic transmittal service order (when available) or another mutually agreed
- -upon type of service order.  Such service order shall be provided in accordance
with industry format and specifications or such format and specifications as 
may be agreed to by the Parties.  Within forty-eight (48) hours of BA's receipt 
of such valid service order, BA shall provide MFS the firm order commitment date
according to the Performance Interval Dates set forth in Schedule 27 by which 
the ULLs covered by such service order will be installed.  In addition, BA shall
provide MFS with the related ULL design information, if available, at least 
forty eight (48) hours prior to the scheduled cutover time.

                                      33
 




<PAGE>
 
          11.6.3   On each ULL order in a Wire Center, MFS and BA will agree on
a cutover time at least forty eight (48) hours before that cutover time. The
cutover time will be defined as a 15-30 minute window within which both the MFS
and BA personnel will make a telephone contact to complete the cutover.

          11.6.4   Within the appointed 15-30 minute cutover time, the MFS
person will call the BA organization designated to coordinate cross-connection
work and when the BA organization is reached in that interval such work will be
promptly performed.

          11.6.5   If MFS requires a change in scheduling, it must contact BA to
issue a supplement to the original order. The negotiations process to determine
the date and time of cutover will then be reinitiated as usual.

          11.6.6   If the MFS person is not ready within the appointed interval 
and if MFS had not called to reschedule the work at least two (2) hours prior to
the start of the interval, MFS shall be liable for the non-recurring charge for
the unbundled elements scheduled for the missed appointment. In addition, non-
recurring charges for the rescheduled appointment will apply.

          11.6.7   If BA is not available or not ready at any time during the 
appointed 15-30 minute interval, MFS and BA will reschedule and BA will waive 
the non-recurring charge for the unbundled elements originally scheduled for 
that interval, whenever those unbundled elements are actually cut over pursuant 
to an agreed-upon rescheduling.

          11.6.8   The standard time expected from disconnection of a live 
Telephone Exchange Service to the connection of the unbundled element to the MFS
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all 
orders consisting of fifteen (15) ULLs or less. Orders involving more than 
fifteen (15) ULLs will require a negotiated interval.

          11.6.9   If unusual or expected circumstances prolong or extend the
time required to accomplish the coordinated cutover, the Party responsible for
such circumstances is responsible for the reasonable labor charges of the other
Party. Delays caused by the Customer are the responsibility of MFS.

          11.6.10  If MFS has ordered INP as part of an ULL installation, BA
will coordinate implementation of INP with the ULL installation. BA's provision
of unbundled elements shall in all cases be subject to the availability of
suitable facilities, to the extent permitted by Section 251 of the Act.

          11.6.11  If MFS requests or approves a BA technician to perform 
services on the network side of the Rate Demarcation Point beyond normal 
installation of the ULLs covered by the service order, BA may charge MFS for any
additional and reasonable labor charges to perform such services. BA may also 
charge MFS its normal overtime rates for services MFS requests to be performed 
outside of BA's normal business hours (M-F,9 am to 5 pm, E.S.T.).

                                      34
<PAGE>
 
      11.7   MAINTENANCE OF UNBUNDLED LOCAL LOOPS

      If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a dispatch,
(iii) BA dispatches a technician, and (iv) such trouble was not caused by BA's
facilities or equipment, then MFS shall pay BA a per-trip charge charge and
labor charges per quarter hour increments for time associated with said
dispatch, as set forth in Exhibit A. In addition this charge also applies in
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA with appropriate dispatch information based on their test results.
If, as the result of MFS instructions, BA is erroneously requested to dispatch
within the Central Office, BA may levy on MFS an appropriate charge.

      11.8   RATES AND CHARGES

      BA shall charge the non-recurring and monthly recurring rates for
unbundled Local Loops and other Network Elements set forth in Exhibit A.


12.0  RESALE -- SECTIONS 251(C)(4) AND 251(B)(1).

      12.1   AVAILABILITY OF RETAIL RATES FOR RESALE

      Each Party shall make available its Telecommunications Services for resale
at retail rates to the other Party in accordance with Section 251(b)(1) of the 
Act.

      12.1   AVAILABILITY OF WHOLESALE RATES FOR RESALE

      BA shall make available to MFS for resale at the wholesale rates set forth
in Exhibit A all Telecommunications Services that BA provides at retail to
Customers that are not Telecommunications Carriers. Such services shall be
provided in accordance with the terms of the applicable retail services
Tariff(s), including, without limitation, user or user group restrictions, as
the case may be, subject to the requirement that such restrictions shall in all
cases comply with the requirements of Section 251 of the Act regarding
restrictions on resale. In addition, BA and MFS shall each allow the resale by
the other of all Telecommunications Services that are offered primarily or
entirely to other Telecommunications Carriers (e.g., Switched and special
Exchange Access Services) at the rates already applicable to such services. BA
shall also allow the resale by MFS of such other non-Telecommunications Services
as BA, in its sole discretion, determines to provide for resale under terms and
conditions to be agreed to by the Parties. If MFS requests resale at wholesale
rates of Telecommunications Services that BA provides at retail to Customers
that are not Telecommunications Carriers before April 1, 1997, the Parties
shall nogotiate and agree upon the terms and conditions for ordering,
provisioning, billing, and maintaining such resale arrangements before MFS
submits any orders for such resale, which terms and conditions are unlikely to
rely on automated interfaces. During the period before April 1, 1997, the
Parties shall negotiate and agree upon, in the form of a separate agreement to
be appended hereto, resale arrangements to apply after that date. Such
arrangements shall, to the extent feasible and

                                      35
 
<PAGE>
 
economically reasonable, employ automated interfaces for ordering, provisioning,
billing, and maintaining resold accounts. The Parties may also agree to
negotiate term and/or volume discounts for resold services.

13.0      COLLOCATION - SECTION 251(C)(6).

          13.1 BA shall offer to MFS Physical Collocation of equipment necessary
for Interconnection (pursuant to Section 4) or for access to unbundled Network
Elements (pursuant to Section 11.0), except that BA may offer only Virtual
Collocation if BA demonstrates to the Commission that Physical Collocation is
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for
the purpose of Interconnection with facilities or services of BA or access to
unbundled Network Elements of BA, except as otherwise mutually agreed to in
writing by the Parties or as required by the FCC or the Commission, subject to
applicable federal and state Tariffs.

          13.2 Although not required to do so by Section 251(c)(6) of the Act, 
by this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to 
Section 4) on a non-discriminatory basis and at comparable rates, terms and 
conditions as MFS may provide to other third parties. MFS shall provide such 
Collocation subject to applicable Tariffs.

          13.3 Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for Physical Collocation for MFS, MFS may elect to 
(i) retain its Virtual Collocation in that premises, and/or (ii) establish 
Physical Collocation in that premises pursuant to current procedures and 
applicable Tariffs. BA will not assess to MFS non-recurring charges for central 
office common area construction to transition existing virtual collocation 
arrangements to physical collocation arrangements in offices where MFS 
previously paid such charges. BA will also waive cage construction charges for 
cages of the same size originally paid for by MFS. MFS shall coordinate with BA 
for rearrangement of MFS's equipment, facilities, and circuits. All applicable 
Physical Collocation recurring charges shall apply.

          13.4 Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for MFS as Virtual Collocation, MFS may elect to (i)
retain its Virtual Collocation in that premises, or (ii) unless it is not 
practical for technical reasons or because of space limitations, convert its 
Virtual Collocation at such premises to Physical Collocation, in which case MFS 
shall coordinate the construction and rearrangement with BA of its equipment, 
facilities, and circuits, and for which MFS shall pay BA at applicable Tariff 
rates. In addition, all Physical Collocation recurring charges shall apply.

          13.5 For both Physical Collocation and Virtual Collocation, the 
Collocating Party shall provide its own or third-party leased transport 
facilities and terminate those transport facilities in equipment located in its 
Physical Collocation space, or in its virtually collocated equipment, at the 
Housing Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

                                      36
<PAGE>
 
     13.6 Collocation shall occur under the terms of each Party's applicable and
available Tariffs. Collocation is offered for network Interconnection between 
the Parties. Unless otherwise agreed to by the Parties or either Party is 
required by applicable law to permit on its collocated premises, neither Party 
shall use a Collocation Arrangement to directly interconnect with a third 
party's equipment or facilities collocated at the same location.


                           SECTION 251(B) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2).

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability 
("LTNP") on a reciprocal basis to each other to the extent technically 
feasible, and in accordance with rules and regulations as from time to time 
prescribed by the FCC and/or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the 
industry pursuant to regulations issued by the FCC and/or the Commission, the 
Parties agree to reciprocally provide Interim Number Portability to each other 
at the prices listed in Exhibit A. Such agreed-upon prices for INP are not 
intended to reflect either Party's views on the cost recovery mechanisms being 
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable
FCC and/or Commission order(s) or regulations mandating the adoption of a
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as
practically possible while minimizing interruption or degredation of service to
their respective Customers. Once PNP is implemented, either Party may withdraw,
at any time and at its sole discretion, its INP offerings, subject to advance
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant
to FCC or Commission regulation, both Parties agree to conform and provide such
PNP. To the extent PNP rates or cost recovery mechanisms are not established by
the applicable FCC or Commission order or regulation mandating the adoption of
PNP, the Parties will negotiate in good faith the charges or cost recovery
mechanism for PNP service at such time as a PNP arrangement is adopted by the
Parties.

          14.1.4  Under either an INP or PNP arrangement, MFS and BA will
implement a process to coordinate LTNP cutovers with ULL conversions (as
described in Section 11 of this Agreement).

                                      37

<PAGE>
 
     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1 A Customer of one Party ("Party A") elects to become a Customer
of the other Party ("Party B"). The Customer elects to utilize the original 
telephone number(s) corresponding to the Telephone Exchange Service(s) it 
previously received from Party A, in conjunction with the Telephone Exchange 
Service(s) it will now receive from Party B. Upon receipt of a service order 
from Party B requesting assignment of the number(s) to Party B, Party A will 
implement an arrangement whereby all calls to the original telephone number(s) 
will be forwarded to a new telephone number(s) designated by Party B, only 
within the same Exchange Area as the original telephone number(s). Party A will 
route the forwarded traffic to Party B over the appropriate traffic exchange 
trunk groups.

          14.2.2 Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties, Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3 Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated 
with those forwarded numbers as directed by Party B. In addition, Party A will 
update the retained numbers in the LIDB with the screening options provided by 
Party B on a per order basis. Party B shall determine which of the screening 
options offered by Party A should apply to the Party B Customer account.

          14.2.4 Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          14.2.5 Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a 
third party that is authorized to act on behalf of the Customer. Party A shall 
provide notification to Party B of third party orders affecting the INP service 
of a Party B customer. The Parties agree to work cooperatively to develop 
procedures or adopt industry standards or practices concerning the initiation 
and termination of INP service in a multi-carrier environment.

          14.2.6 The INP service offered herein shall not initially apply to NXX
Codes 555, 915, 976, or 950, or for Feature Group A or coin telephone service. 
Upon request of either Party, provision of INP to these services will be 
mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any 
arrangement that would render the forwarded call Toll Traffic.

                                      38

<PAGE>
 
          14.2.7 The ordering of INP arrangements and the exchange of screening 
information shall be made in accordance with industry-accepted (e.g. OBF 
developed) format and specifications to the extent they have been implemented by
the Parties.

     14.3 PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS 
(FLEXDID) Either Party may also request INP through Direct Inward Dial Trunks 
pursuant to any applicable Tariffs.

     14.4 PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION Where 
either Party has activated an entire NXX for a single Customer, or activated a 
substantial portion of an NXX for a single Customer, with the remaining numbers 
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other 
Party, the first Party shall cooperate with the second Party to have the entire 
NXX reassigned in the LERG (and associated industry databases, routing tables, 
etc.) to an End Office operated by the second Party. Such transfer will be 
accomplished with appropriate coordination between the Parties and subject to 
appropriate industry lead-times for movements of NXXs from one switch to 
another. Neither Party shall charge the other in connection with this 
coordinated transfer.

     14.5 RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described 
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed 
numbers should be received by each Customer's chosen LEC as if each call to the 
Customer had been originally addressed by the caller to a telephone number 
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to 
accomplish this objective where INP is employed, the Parties shall utilize the 
process set forth in this subsection 14.5 whereby terminating compensation on 
calls subject to INP will be passed from the Party (the "Performing Party") 
which performs the INP to the other Party (the "Receiving Party") for whose 
Customer the INP is provided.

          14.5.1 The Parties shall individually and collectively make best 
efforts to track and quantify INP traffic between their networks based on the
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving
Party shall charge the Performing Party for each minute of INP traffic at the
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other
compensation charges for terminating such traffic, except as provided in
subsection 14.5.2.

          14.5.2 By the Interconnection Activation Date in each LATA, the 
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal 
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra 
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as 
Transit Traffic. On the date which is six (6) months after the Interconnection 
Activation Date, the Parties shall establish new INP traffic percentages to be 
applied in the prospective six (6) month period, based

                                      39
<PAGE>
 
on the Performing Party's choice of actual INP traffic percentages from the 
preceding six (6) month period of historic data of all traffic in the LATA.

          14.5.3 The INP Traffic Rate shall be equal to the sum of:

  (Recip Traffic percentage times the Reciprocal Compensation Rate set forth
                            -----
in Exhibit A)
                                     plus
                                     ----
      (Intra Traffic percentage times Receiving Party's effective intrastate FGD
                                -----
rates)
                                     plus
                                     ----
      (Inter Traffic percentage times Receiving Party's effective interstate FGD
                                -----
rates)

     The Receiving Party shall compensate the Performing Party for its billing 
and collection of charges for the intrastate and interstate FGD access services 
provided by the Receiving Party to a third party through the greater of (i) the 
difference between the intrastate and interstate FGD rates of the Receiving 
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     14.6 RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this Section 14, in 
light of the FCC's First Report and Order and Further Notice of Proposed 
Rulemaking, adopted June 27, 1996, in CC docket 95-116 (the "Order"), the 
Parties stipulate and agree as follows:

          14.6.1 The rates listed in Exhibit A for the provision of INp are 
appropriate amounts that each Party providing INP service should recover for the
provision of those INP functionalities in BA's operating territory. For the INP 
functions it provides, each Party should be allowed to recover these amounts in 
a manner consistent with any final FCC and/or Commission order on INP cost 
recovery (such as a state-wide fund contributed to by all telecommunications 
carriers).

          14.6.2 Within three (3) weeks of the Effective Date, the parties will 
jointly seek a Commission proceeding and ruling to develop and implement an INP 
cost recovery mechanism consistent with the policy described in the Order and/or
any subsequent FCC or Commission decision.

          14.6.3 Until such time as a final FCC and/or Commission order, 
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the other Party at the INP rates listed in Exhibit A. All revenues 
received by the providing Party from its provision of INP service to the other 
Party shall be placed into an escrow fund maintained by or tracked separately by
the providing Party. Upon issuance of a final FCC and/or Commission order, and 
to the extent that it permits the Party providing INP to recover the associated 
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal

                                      40
     
<PAGE>
 
to the amount it recovers from such fund for its provision of INP service to the
purchasing Party from the Effective Date, provided that in no event shall the 
refund amount exceed the aggregate amount the providing Party has received from 
the purchasing Party for INP services. If no such fund is ordered or 
established, the providing Party shall retain the full amount of the revenues 
tracked or held in escrow by it pursuant to this subsection 14.6.3.

          14.6.4 The Parties agree that neither Party waives its rights to 
advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.


15.0 DIALING PARITY -- SECTION 251(B)(3).

     BA and MFS shall each provide the other with nondiscriminatory access to 
such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.


16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4).

     Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C. (S)
224, as set forth in Exhibit A, where facilities are available, on terms, 
conditions and prices comparable to those offered to any other entity pursuant 
to each Party's applicable Tariffs. Where no such Tariffs exist, such access 
shall be provided in accordance with the requirements of 47 U.S.C. (S) 224, 
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C. (S) 224 
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the 
appropriateness of applying such changes on a retroactive basis to the date 
hereof. If the Parties are unable to agree on the necessary changes to the 
existing arrangements or the appropriateness of applying them on a retroactive 
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.


17.0 DATABASES AND SIGNALING.

     17.1 Each Party shall provide the other Party with access to databases and 
associated signaling necessary for call routing and completion by providing SS7 
Common Channel Signaling (CCS) Interconnection in accordance with existing 
Tariffs, and Interconnection and access to 800/888 databases, LIDB, and any 
other necessary databases in accordance with existing Tariffs and/or agreements 
with other unaffiliated carriers, as set forth in the Exhibit A. Alternatively, 
either Party may secure CCS Interconnection from a commercial

                                      41

<PAGE>
 
SS7 hub provider, and in that case the other Party will permit the purchasing 
Party to access the same databases as would have been accessible if the 
purchasing party had connected directly to the other Party's CCS network.

     17.2  The Parties will provide CCS Signaling to one another, where and as 
available, in conjunction with all Local Traffic, Toll Traffic, Meet Point 
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between 
their respective networks, including all CLASS features and functions, to the 
extent each Party offers such features and functions to its Customers. All CCS 
Signaling parameters will be provided upon request (where available), including 
called party number, calling party number, originating line information, calling
party category, and charge number. All privacy indicators will be honored. The 
Parties will follow all Ordering and Billing Forum-adopted standards pertaining 
to CIC/OZZ codes. Where CCS Signaling is not available, in-band multi-frequency 
(MF) wink start signaling will be provided. Any such MF arrangement will require
a separate local trunk circuit between the Parties' respective switches. In such
an arrangement, each Party will outpulse the full ten-digit telephone number of 
the called party to the other Party.


     17.3  Each Party shall provide trunk groups, where available and upon 
reasonable request, that are configured utilizing the B8ZS ESF protocol for 64 
kbps clear channel transmission to allow for ISDN interoperability between the 
Parties' respective networks.

     17.4  The following publications describe the practices, procedures and 
specifications generally utilized by BA for signaling purposes and is listed 
herein to assist the Parties in meeting their respective Interconnection 
responsibilities related to Signaling:

           (a) Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC 
Networks-Signaling; and

           (b) Bell Atlantic Supplement Common Channel Signaling Network 
Interface Specification (BA-905).

     17.5  Each Party shall charge the other Party mutual and reciprocal rates 
for CCS Signaling as follows: BA shall charge MFS in accordance with Exhibit A 
hereto and applicable Tariffs; MFS shall charge BA rates equal to the rates BA 
charges MFS, unless MFS'S Tariffs for CCS signaling provide for lower generally 
available rates, in which case MFS shall charge BA such lower rates.

18.0 COORDINATED SERVICE ARRANGEMENTS.

     18.1 INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its
service provider from BA to MFS, or from MFS to BA, and does not retain its
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides
 

















<PAGE>
 
details on the Customer's new number or provide other appropriate information to
the extent known. Referral Announcements shall be provided reciprocally, free of
charge to either the other Party or the Customer to the extent the providing
Party does not charge its own customers for such service, for a period of not
less than four (4) months after the date the Customer changes its telephone
number in the case of business Customers and not less than sixty (60) days after
the date the Customer changes its telephone number in the case of residential
Customers. However, if either Party provides Referral Announcements for
different periods than the above respective periods when its Customers change
their telephone numbers, such Party shall provide the same level of service to
Customers of the other Party.

     18.2 COORDINATED REPAIR CALLS. MFS and BA will employ the following 
procedures for handling misdirected repair calls:

          18.2.1    MFS and BA will educate their respective Customers as to the
correct telephone numbers to call in order to access their respective repair
bureaus.

          18.2.2    To the extent Party A is identifiable as the correct 
provider of service to Customers that make misdirected repair calls to Party B, 
Party B will immediately refer the Customers to the telephone number provided by
Party A, or to an information source that can provide the telephone number of
Party A, in a courteous manner and at no charge. In responding to misdirected
repair calls, neither Party shall make disparaging remarks about the other
Party, its services, rates, or service quality.

          18.2.3    MFS and BA will provide their respective repair contact 
numbers to one another on a reciprocal basis.

     18.3 CUSTOMER AUTHORIZATION. In order for either Party to order or 
terminate service on the behalf of the other Party's Customer, the requesting 
Party must have proper written authorization from the customer in its files, and
provide a copy of such authorization to the other Party upon request. In the 
event the requesting Party (i) fails to provide a copy of the Customer's proper 
written authorization upon request, (ii) requests changes in the other Party's 
Customer's service without having such authorization in its files, or (iii) 
mistakenly changes the other Party's Customer's service, the requesting Party 
shall be liable to the other Party for all charges that would be applicable to 
the Customer for restoring service to the other Party.

19.0 DIRECTORY SERVICES ARRANGEMENTS

     BA will, upon request, provide the following directory services to MFS in 
accordance with the terms set forth herein. In this Section 19, references to a 
MFS Customer's "primary listing" shall mean such Customer's name, address, and 
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP 
arrangements with BA or any other carrier within the geographic area covered in 
the relevant BA directory.

                                      43

<PAGE>
 
     19.1 DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

          19.1.1  BA will include the MFS Customer's primary listing in its 
"White Pages" directory (residence and business listings) and "Yellow Pages" 
directory (business listings) that cover the address of the Customer. Listings
of MFS's Customers will be interfiled with listings of BA's Customers and the
Customers of other LECs included in the BA directories. MFS will pay BA a non-
recurring charge as set forth in Exhibit A for providing such service for each
MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as the
case may be, for additional and foreign white page listings and other white 
pages services for MFS's Customers. BA will not require a minimum number of
listings per order.

          19.1.2  BA will also include the MFS Customer's primary listing in 
BA's directory assistance database on the same basis the BA's own Customers are 
included, as well as in any electronic directories in which BA's Customers are
ordinarily included, for no charge other than the charges identified in
subsection 19.1.1.

          19.1.3  BA will distribute to MFS Customers copies of their primary 
white pages and yellow pages directories at the same time and on the same basis 
that BA distributes primary directories to its own Customers. BA will also 
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional 
directories from BA's Directory Fulfillment Centers, which Centers will provide 
such additional directories for the same charges applicable to comparable 
requests by BA Customers.

          19.1.4  BA will include all MFS NXX codes associated with the areas to
which each directory pertains, along with BA's own NXX codes in any maps or 
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same 
manner as BA's NXX information.

          19.1.5  MFS shall provide BA with daily listing information on all new
MFS Customers in the format required by BA or a mutually-agreed upon industry 
standard format. The information shall include the Customer's name, address, 
telephone number, the delivery address and number of directories to be 
delivered, and, in the case of a business listing, the primary business heading 
under which the business Customer desires to be placed, and any other 
information necessary for the publication and delivery of directories. MFS will 
also provide BA with daily listing information showing Customers that have 
disconnected or terminated their service with MFS. BA will provide MFS with 
confirmation of listing order activity within forty eight (48) hours.

          19.1.6  BA will accord MFS's directory listing information the same 
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be 
used solely for the purpose of providing directory services; provided, however, 
that BA may use or license information contained in its directory listings for 
direct marketing purposes so long as the MFS Customers are not separately 
identified as such; and provided further that MFS may identify those of its 
Customers that request

                                      44

<PAGE>
 
that their names not be sold for direct marketing purposes, and BA will honor 
such requests to the same extent as it does for its own Customers.

            19.1.7  BA or BA's publisher shall provide MFS with a report of all 
MFS Customer listings ninety (90) days prior to directory publication in such 
form and format as may be mutually agreed to by both Parties. Both Parties shall
use their best efforts to ensure the accurate listing of such information. BA 
will also provide MFS, upon request, a copy of the BA listings standards and 
specifications manual. In addition, BA will provide MFS with a listing of Yellow
Pages headings and directory close schedules on an ongoing basis.

            19.1.8  MFS will adhere to all practices, standards, and ethical 
requirements of BA with regard to listings, and, by providing BA with listing 
information, warrants to BA that MFS has the right to place such listings on 
behalf of its Customers. MFS agrees that it will undertake commercially 
practicable and reasonable steps to attempt to ensure that any business or 
person to be listed is authorized and has the right (i) to provide the product 
or service offered, and (ii) to use any personal or corporate name, trade name 
or language used in the listing.

            19.1.9  BA's liability to MFS in the event of a BA error in or
omission of a listing shall be subject to the same limitations that BA's
liability to its own Customers are subject to. In addition, MFS agrees to take,
with respect to its own Customers, all reasonable steps to ensure that its and
BA's liability to MFS's Customers in the event of a BA error in or omission of a
listing shall be subject to the same limitations that BA's liability to its own
Customers are subject to.

      19.2  YELLOW PAGE MAINTENANCE.  The Parties agree to work cooperatively to
ensure that Yellow Page advertisements purchased by Customers that switch their
service to MFS (including Customers utilizing MFS-assisgned telephone numbers
and MFS Customers utilizing LTNP) are maintained without interruption. BA will
allow MFS Customers to purchase new Yellow Pages advertisements without
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. BA and MFS may implement a commission program whereby MFS may, at
MFS's sole discretion, act as a sales, billing and collection agent for Yellow
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

      19.3  SERVICE INFORMATION PAGES.  BA will include in the "Customer Guide" 
or comparable section of the applicable white pages directories listings 
provided by MFS for MFS's installation, repair and customer service and other 
essential service oriented information, as agreed by the Parties, including 
appropriate identifying logo. Such listings shall appear in the manner agreed to
by the Parties. BA shall not charge MFS for inclusion of this essential 
service-oriented information, but reserves the right to impose charges on other 
information MFS may elect to submit and BA may elect to accept for inclusion in 
BA's white pages directories. BA will provide MFS with the annual directory 
close dates and reasonable notice of any changes in said dates.

                                      45
<PAGE>
 
      19.4  DIRECTORY ASSISTANCE (DA); CALL COMPLETION

            19.4.1  Upon request, BA will provide MFS with directory assistance 
and/or call completion services substantially in accordance with the terms set 
forth in the form Directory Assistance and Call Completion Services Agreement 
appended hereto as Exhibit C.

            19.4.2  Also upon request, BA will provide to MFS operator services 
trunk groups, utilizing Feature Group D type signaling, with ANI, minus OZZ, 
when interconnecting to the BA operator services network.

20.0  COORDINATION WITH TARIFF TERMS

      20.1  The Parties acknowledge that some of the services, facilities, and 
arrangements described herein are or will be available under and subject to the 
terms of the federal or state tariffs of the other Party applicable to such 
services, facilities, and arrangements. To the extent a Tariff of the providing 
Party applies to any service, facility, and arrangement described herein, the 
Parties agree as follows:

            20.1.1  Those rates and charges set forth in Exhibit A for the 
services, facilities, and arrangements described herein that are designated with
an asterisk shall remain fixed for the initial term of the Agreement, 
notwithstanding that such rates may be different from those contained in an 
effective, pending, or future Tariff of the providing Party (including any 
changes to such Tariff subsequent to the Effective Date). Those rates and 
charges for services, facilities, and arrangements that are not designated with 
an asterisk, and reference or are identical to a rate contained in an existing 
Tariff of the providing Party, shall conform with those contained in the 
then-prevailing Tariff and vary in accordance with any changes that may be made 
to the Tariff rates and charges subsequent to the Effective Date. Even the 
asterisked fixed rates and charges shall be changed to reflect any changes in
the Tariff rates and charges they reference, however, if the Parties agree to
adopt the changed Tariff rates and charges.

      20.2  Except with respect to the rates and charges described in subsection
20.1 above, all other terms contained in an applicable Tariff of the providing 
Party shall apply in connection with its provision of the particular service, 
facility, and arrangement hereunto.

21.0  INSURANCE

      21.1  MFS shall maintain, during the term of this Agreement, all insurance
and/or bonds required by law and necessary to satisfy its obligations under this
Agreement, including, without limitation, its obligations set forth in Section 
25 hereof. At a minimum and without limiting the foregoing covenant, MFS shall 
maintain the following insurance:

            (a)  Commercial General Liability Insurance, on an occurrence basis,
      including but not limited to, premises-operations, broad form property
      damage, products/completed

                                      46
<PAGE>
 
     operations, contractual liability, independent contractors, and personal
     injury, with limits of at least $1,000,000 combined single limit for each
     occurrence.

          (b)  Automobile Liability, Comprehensive Form, with limits of at least
     $500,000 combined single limit for each occurrence.

          (c)  Excess Liability, in the umbrella form, with limits of at least 
     $15,000,000 combined single limit for each occurrence.

          (d)  Worker's Compensation Insurance as required by law and Employer's
     Liability Insurance with limits of not less than $1,000,000 per occurrence.

     21.2 MFS shall name BA as an additional insured on the foregoing insurance.
MFS agrees that MFS's insurer(s) and anyone claiming by, through, under or on 
behalf of MFS, shall have no claim, right of action, or right of subrogation, 
against BA, BA's affiliated companies, or the directors, officers or employees 
of BA or BA's affiliated companies, based on any loss or liability insurable 
under the foregoing insurance.

     21.3 MFS shall, within two (2) weeks of the date hereof and on a quarterly 
basis thereafter, furnish certificates or other adequate proof of the foregoing 
insurance. The certificates or other proof of the foregoing insurance shall be 
sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court House 
Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall require its 
agents, representatives, or contractors, if any, that may enter upon the 
premises of BA or BA's affiliated companies to maintain similar and appropriate 
insurance and, if requested, to furnish BA certificates or other adequate proof 
of such insurance. Certificates furnished by MFS or MFS's agents, 
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to 
cancellation of, or any material change in, the insurance."


22.0 TERM AND TERMINATION.

     22.1 This Agreement shall be effective as of the date first above written 
and continue in effect until July 1, 1999, and thereafter the Agreement shall 
continue in force and effect unless and until terminated as provided herein. 
Upon the expiration of the initial term, either Party may terminate this 
Agreement by providing written notice of termination to the other Party, such 
written notice to be provided at least ninety (90) days in advance of the date 
of termination. In the event of such termination, those service arrangements 
made available under this Agreement and existing at the time of termination 
shall continue without interruption under (a) a new agreement executed by the 
Parties, (b) standard Interconnection terms and conditions approved and made 
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of 
this Agreement on a month-to month basis until such time as (a), (b), or (c) 
becomes available.

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<PAGE>
 
     22.2 For service arrangements made available under this Agreement and 
existing at the time of termination, if the standard Interconnection terms and 
conditions or Tariff terms and conditions result in the non-terminating Party 
physically rearranging facilities or incurring programming expense, the 
non-terminating Party shall be entitled to recover such rearrangement or 
programming costs, from the terminating Party. By mutual agreement, the Parties 
may jointly petition the appropriate regulatory bodies for permission to have 
this Agreement supersede any future standardized agreements or rules as such 
regulators might adopt or approve.

     22.3 If either Party defaults in the payment of any amount due hereunder,
or if either Party violates any other provision of this Agreement, and such
default or violation shall continue for sixty (60) days after written notice
thereof, the other Party may terminate this Agreement and services hereunder by
written notice; provided the other Party has provided the defaulting Party and
the appropriate federal and/or state regulatory bodies with written notice at
least twenty five (25) days' prior to terminating service. Notice shall be
posted by certified mail, return receipt requested. If the defaulting Party
cures the default or violation within the twenty five (25) day period, the other
Party will not terminate service or this Agreement but shall be entitled to
recover all costs, if any, incurred by it in connection with the default or
violation, including, without limitation, costs incurred to prepare for
termination of service.

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES ANY
WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE PARTIES
DISCLAIM THE IMPLIED WARRANTIES OR MERCHANTABILITY OR OF FITNESS FOR A
PARTICULAR PURPOSE.

24.0 CANCELLATION CHARGES.

     Except as provided in this Agreement or as otherwise provided in any 
applicable Tariff no cancellation charges shall apply.

25.0 INDEMNIFICATION.

     25.1 Each Party agrees to release, indemnify, defend and hold harmless the
other Party from and against all losses, claims, demands, damages, expenses,
suits or other actions, or any liability whatsoever, including, but not limited
to, costs and attorneys' fees (collectively, a "Loss"), (a) whether suffered,
made,instituted, or asserted by any other party or person, (i) relating to
personal injury to or death of any person, or for loss, damage to, or
destruction of real and/or personal property, whether or not owned by others,
incurred during the term of this Agreement and to the extent proximately caused
by the acts or omissions of the indemnifying Party, regardless of the form of
action, or (ii) arising out of BA's listing of the directory information
provided by
<PAGE>
 
MFS pursuant to subsection 19.1, or (b) suffered, made, instituted, or asserted 
by its own customer(s) against the other Party arising out the other Party's
provision of services to the indemnifying Party under this Agreement.
Notwithstanding the foregoing indemnification, nothing in this such Section 25.
shall affect or limit any claims, remedies, or other actions the indemnifying
Party may have against the indemnified Party under this Agreement, any other
contract, or any applicable Tariff(s), regulations or laws for the indemnified
Party's provision of said services.

     25.2 The indemnification provided herein shall be conditioned upon:

          (a)  The indemnified Party shall promptly notify the indemnifying
     Party of any action taken against the indemnified Party relating to the
     indemnification.

          (b)  The indemnifying Party shall have sole authority to defend any
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c)  In no event shall the indemnifying Party settle or consent to any
     judgment pertaining to any such action without the prior written consent of
     the indemnified Party, which consent shall not be unreasonably withheld.

          (d)  The indemnified Party shall, in all cases, assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e)  The indemnified Party shall offer the indemnifying Party all 
     reasonable cooperation and assistance in the defense of any such action.

     25.3 In addition to its indemnity obligations under subsection 25.1, each 
Party shall provide, in its tariffs and contracts with its Customers that relate
to any Telecommunications Service or Network Element provided or contemplated 
under this Agreement, that in no case shall such Party or any of its agents, 
contractors or others retained by such parties be liable to any Customer or 
third party for (i) any Loss relating to or arising out of this Agreement, 
whether in contract or tort, that exceeds the amount such Party would have 
charged the applicable Customer for the service(s) or function(s) that gave rise
to such Loss, and (ii) any Consequential Damages (as defined in subsection 26.2 
below).

26.0 LIMITATION OF LIABILITY.

     26.1 Except as may be provided pursuant to Section 27 below, the liability 
of either Party to the other Party for damages arising out of failure to comply 
with a direction to install, restore or terminate facilities; or out of 
failures, mistakes, omissions, interruptions, delays, errors, or defects 
occurring in the course of furnishing any services, arrangements, or facilities 
hereunder shall be determined in accordance with the terms of the applicable 
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro

                                      49
<PAGE>
 
rata monthly charge for the period in which such failures, mistakes, omissions,
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for 
such failures, mistakes, omissions, interruptions, delays, errors or defects.

     26.2 Neither Party shall be liable to the other in connection with the 
provision or use of services offered under this Agreement for indirect, 
incidental, consequential, reliance or special damages, including, (without 
limitation) damages for lost profits (collectively, "Consequential Damages"), 
regardless of the form of action, whether in contract, warranty, strict
liability, or tort, including, without limitation, negligence of any kind, even
if the other Party has been advised of the possibility of such damages;
provided, that the foregoing shall not limit a Party's obligation under Section
25.

     26.3 The Parties agree that neither Party shall be liable to the customers 
of the other Party in connection with its provision of services to the other 
Party under this Agreement. Nothing in this Agreement shall be deemed to create 
a third party beneficiary relationship between the Party provided the service 
and the customers of the Party purchasing the service. In the event of a dispute
involving both Parties with a customer of one Party, both Parties shall assert 
the applicability of any limitations of liability to customers that may be 
contained in either Party's applicable Tariff(s).

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

     27.1 CERTAIN DEFINITIONS. When used in this Section 27, the following terms
shall have the meanings indicated:

          27.1.1  "Specified Performance Breach" means the failure by BA to meet
the Performance Criteria for any one of the three Specified Activities for a 
period of three (3) consecutive calendar months.

          27.1.2  "Specified Activity" means any of the following activities:

          (a)  the installation by BA of Unbundled Local Loop Elements for MFS
     ("ULL Installation");

          (b)  BA's provision of INP to MFS or

          (c)  repair of out of service problems for MFS ("Out of Service
     Repairs")

          27.1.3  "Performance Criteria" means, with respect to any calendar 
month during the term of this Agreement, the performance by BA during such month
of each Specified Activity (except Out-of-Service Repairs) shown in Schedule 
27.0, within the time interval shown, in at least eighty percent (80%) of the 
covered instances. BA shall perform the Out-of-Service Repairs within the 
specified time interval in at least seventy percent (70%) of the covered

                                      50
<PAGE>
 
instances. Within one week of each anniversary of the Effective Date, the
Parties shall jointly review BA's actual network-wide monthly performance
percentages for Out-of-Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual
percentages for any three consecutive month period and/or the full preceding
year, up to and including an eighty percent (80%) standard, as the Out-of-
Service Repairs percentage standard applicable to the following year.

     27.2 PERFORMANCE STANDARDS.  BA shall exercise best efforts to meet the 
Performance Criteria for the three Specified Activities. In the event BA fails 
to meet the Performance Criteria at any time during the term of this Agreement, 
MFS shall be entitled to pursue all remedies set forth in the applicable BA 
Tariffs, except as may be agreed to by the Parties. In addition, if BA commits a
Specified Performance Breach during the term of this Agreement, the Parties 
agree to meet immediately to determine whether any liquidated damages provisions
are appropriate as an amendment hereof in light of such Breach and, if so, the
terms therein; provided, however, that if BA commits a Specified Performance
Breach during initial nine (9) months of this Agreement, the Parties agree to
meet at the end of the nine-month period. If the Parties are unable to agree as
to the appropriateness of the liquidated damages provisions and/or the terms
therein within ninety (90) days after the date of the first meeting pursuant to
this subsection, or if no such meeting has occurred within ninety (90) days of
the end of the nine-month period for reasons other than the mutual agreement of
the Parties, the Parties agree to submit to arbitration such disagreement and
request that the arbitrators base their decision on comparable ILEC-CLEC
interconnection agreements. Unless otherwise agreed to by the Parties, the
arbitration shall be conducted by a panel of three (3) arbitrators, one to be
appointed by each Party pursuant to CPR's Non-Administered Arbitration Rules and
subject to the United States Arbitration Act (9 U.S.C. (SS) 1-16), to be
conducted in Arlington, Virginia. The Parties agree that the liquidated damages
provisions, if any, finally determined by the arbitral process shall be adopted
as an amendment to this Agreement.

     27.3 LIMITATIONS.  In no event shall BA be deemed to have failed to meet 
any of the Performance Criteria if:

          27.3.1 BA's failure to meet or exceed any of the Performance Criteria 
is caused, directly or indirectly, by a Delaying Event. A "Delaying Event" means
(a) a failure by MFS to perform any of its obligations set forth in this 
Agreement (including, without limitation, the Implementation Schedule and the 
Joint Grooming Plan), (b) any delay, act or failure to act by a Customer, agent,
representative, or subcontractor of MFS or (c) any Force Majeure Event. If a 
Delaying Event prevents or delays BA from performing a Specified Activity, then 
such Specified Activity shall be excluded from the calculation of BA's 
compliance with the Performance Criteria, provided BA performs the Specified 
Activity in the course of its normal service cycle once the Delaying Event no 
longer exists; or

          27.3.2 the Parties agree to a time interval with respect to a 
particular order that exceeds the interval set forth in Schedule 27. In such 
event, the time interval for BA's performance of the Specified Activit(ies) set 
forth in the order shall be extended to such later date agreed to by the 
Parties.

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<PAGE>
 
     27.4 SERVICE QUALITY STANDARDS. MFS agrees to specific performance 
standards associated with quality of service requests as specified in Schedule
27.1. Should MFS fail to meet these service quality standards, during a period
in which BA has failed to meet the Performance Criteria, BA's failure during 
such time period shall be excused and not apply toward the calculation of a 
Specified Performance Breach.

     27.5 RECORDS. Each Party shall maintain complete and accurate records in 
the manner and format agreed to by the Parties, on a monthly basis, of BA's 
performance under this Agreement of each Specified Activity and its compliance 
with the Performance Criteria during the initial nine-month period. Each Party 
shall provide to the other Party such records in a self-reporting format on a 
monthly basis. The Parties agree that such records shall be deemed "Proprietary 
Information" for purposes of subsection 29.4.


28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

     28.1 Each Party represents and warrants that it is now and will remain in 
compliance with all laws, regulations, and orders applicable to the performance 
of its obligations hereunder (collectively, "Applicable Laws"). Each Party shall
promptly notify the other Party in writing of any governmental action that 
suspends, cancels, withdraws, limits, or otherwise materially affects its 
ability to perform its obligations hereunder.

     28.2 The Parties understand and agree that this Agreement will be filed 
with the Commission and may thereafter be filed with the FCC. The Parties 
covenant and agree that this Agreement is satisfactory to them as an agreement 
under Section 251 of the Act. Each Party covenants and agrees to fully support 
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek 
regulatory relief and otherwise seek redress from each other regarding 
performance and implementation of this Agreement.

     28.3 The Parties recognize that the FCC is currently promulgating 
regulations implementing the Act, including, without limitation, Sections 251, 
252, and 271 thereof (the "FCC Regulations"), that may effect the terms 
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties 
agree to make only the minimum revisions necessary to eliminate the 
inconsistency. Such minimum changes to conform this Agreement to the FCC 
Regulations shall not be considered material, and shall not require further 
Commission approval (beyond any Commission approval required under Section 
252(e) of the Act).

     28.4 In the event any Applicable Law other than the FCC Regulations 
requires modification of any material term(s) contained in this Agreement, 
either Party may require a renegotiation of the term(s) that require direct 
modification as well as of any term(s) that are reasonably affected thereby. If 
neither Party requests a renegotiation or if an Applicable Law requires 
modification of any non-material term(s), then the Parties agree to make only 
the minimum

                                      52
<PAGE>
 
modifications necessary, and the remaining provisions of this Agreement shall 
remain in full force and effect. For purposes of this subsection 28.4 and 
without limitation of any other modifications required by Applicable Laws, the 
Parties agree that any modification required by Applicable Laws (i) to the 
two-tier Reciprocal Call Termination compensation structure for the transport 
and termination of Local Traffic described in Exhibit A, or (ii) that affects 
either Party's receipt of reciprocal compensation for the transport and 
termination of Local Traffic, shall be deemed to be a modification of a material
term that requires immediate good faith renegotiation between the Parties. Until
such renegotiation results in a new agreement or an amendment to this Agreement 
between the Parties, the Parties agree that (y) in the case of (i) above, they 
will pay each other appropriate transport charges in addition to the usual call
termination charge for Local Traffic that it delivers to the other Party's Local
Serving Wire Center, provided each Party continues to offer the option of 
delivering Local Traffic to another IP in the LATA at the usual call termination
charge only, and (z) in the case of (ii) above, the Party whose receipt of 
reciprocal compensation is affected shall not be obligated to pay the other 
Party reciprocal compensation for the other Party's transport and termination of
the same kind of Local Traffic delivered by the affected Party in excess of what
the affected Party is permitted to receive and retain.

29.0 MISCELLANEOUS.

     29.1 AUTHORIZATION.

          29.1.1  BA is a corporation duly organized, validly existing and in 
good standing under the laws of the Commonwealth of Virginia and has full power 
and authority to execute and deliver this Agreement and to perform the 
obligations hereunder on behalf of BA.

          29.1.2  MFS is a corporation duly organized, validly existing and in 
good standing under the laws of the State of Delaware and has full power and 
authority to execute and deliver this Agreement and to perform its obligations 
hereunder.

     29.2 INDEPENDENT CONTRACTOR.  Each Party shall perform services hereunder 
as an independent contractor and nothing herein shall be construed as creating 
any other relationship between the Parties. Each Party and each Party's 
contractor shall be solely responsible for the withholding or payment of all 
applicable federal, state and local income taxes, social security taxes and 
other payroll taxes with respect to their employees, as well as any taxes, 
contributions or other obligations imposed by applicable state unemployment or 
workers' compensation acts. Each Party has sole authority and responsibility to 
hire, fire and otherwise control its employees.

     29.3 FORCE MAJEURE.  Neither Party shall be responsible for delays or 
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in 
performance were foreseen or foreseeable as of the date of this Agreement, 
including, without limitation: adverse weather conditions, fire, explosion, 
power failure, acts of God, war, revolution, civil commotion, or acts of public 
enemies; any law, order, regulation, ordinance or requirement of any government 
or legal body; or labor unrest, including, without limitation, strikes, 
slowdowns, picketing or boycotts; or delays caused by the 

                                      53

<PAGE>
 
other Party or by other service or equipment vendors; or any other circumstances
beyond the Party's reasonable control. In such event, the affected Party shall, 
upon giving prompt notice to the other Party, be excused from such performance 
on a day-to-day basis to the extent of such interferences (and the other Party 
shall likewise be excused from performance of its obligations on a day-for-day 
basis to the extent such Party's obligations relate to the performance so 
interfered with). The affected Party shall use its best efforts to avoid or 
remove the cause(s) of non-performance and both Parties shall proceed to perform
with dispatch once the cause(s) are removed or cease.

     29.4 CONFIDENTIALITY.

          29.4.1  All information, including but not limited to specification, 
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches, 
models, samples, tools, technical information, data, employee records, maps, 
financial reports, and market data, (i) furnished by one Party to the other 
Party dealing with customer specific, facility specific, or usage specific 
information, other than customer information communicated for the purpose of 
publication or directory database inclusion, or (ii) in written, graphic, 
electromagnetic, or other tangible form and marked at the time of delivery as 
"Confidential" or "Proprietary," or (iii) communicated orally and declared to 
the receiving Party at the time of delivery, or by written notice given to the 
receiving Party within ten (10) days after delivery, to be "Confidential" or 
"Proprietary" (collectively referred to as "Proprietary Information"), shall 
remain the property of the disclosing Party.

          29.4.2  Each Party shall keep all of the other Party's Proprietary 
Information confidential and shall use the other Party's Proprietary Information
only for performing the covenants contained in this Agreement. Neither Party 
shall use the other Party's Proprietary Information for any other purpose except
upon such terms and conditions as may be agreed upon between the Parties in 
writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality 
and non-use set forth in this Agreement do not apply to such Proprietary 
Information that:

          (a)     was, at the time of receipt, already known to the receiving
     Party free of any obligation to keep it confidential as evidenced by
     written records prepared prior to delivery by the disclosing Party; or

          (b)     is or becomes publicly known through no wrongful act of the 
     receiving Party; or

          (c)     is rightfully received from a third person having no direct or
     indirect secrecy or confidentiality obligation to the disclosing Party with
     respect to such information; or

          (d)     is independently developed by an employee, agent, or
     contractor of the receiving Party that is not involved in any manner with
     the provision of services pursuant to this Agreement and does not have any
     direct or indirect access to the Proprietary Information; or

                                      54
<PAGE>
 
          (e)    is approved for release by written authorization of the 
     disclosing Party; or

          (f)    is required to be made public by the receiving Party pursuant
     to applicable law or regulation, provided that the receiving Party shall
     give sufficient notice of the requirement to the disclosing Party to enable
     the disclosing Party to seek protective orders.

          29.4.4 Upon request by the disclosing Party, the receiving Party shall
return all tangible copies of Proprietary Information, whether written, graphic 
or otherwise, except that the receiving Party may retain one copy for archival 
purposes only.

          29.4.5 Notwithstanding any other provision of this Agreement, the 
provisions of this subsection 29.4 shall apply to all Proprietary Information 
furnished by either Party to the other in furtherance of the purpose of this 
Agreement, even if furnished before the Effective Date.

     29.5 CHOICE OF LAW.  The construction, interpretation and performance of 
this Agreement shall be governed by and construed in accordance with the laws of
the state in which this Agreement is to be performed, except for its conflicts 
of laws provisions. In addition, insofar as and to the extent federal law may 
apply, federal law will control.

     29.6 TAXES

          29.6.1. In General. With respect to any purchase hereunder of 
                  ----------
services, facilities or arrangements, if any federal, state or local tax, fee, 
surcharge or other tax-like charge (a "Tax") is required or permitted by 
Applicable Law (as defined in subsection 28.1) to be collected from the 
purchasing Party by the providing Party, then (i) the providing Party shall 
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

          29.6.2. Taxes Imposed on the Providing Party. With respect to any 
                  ------------------------------------
purchase hereunder of services, facilities or arrangements, if any federal, 
state or local Tax is imposed by Applicable Law on the receipts of the providing
Party, which Law permits the providing Party to exclude certain receipts 
received from sales for resale to a public utility, distributor, telephone 
company, local exchange carrier, telecommunications company or other 
communications company ("Telecommunications Company"), such exclusion being 
based solely on the fact that the purchasing Party is also subject to a tax 
based upon receipts ("Receipts Tax"), then the purchasing Party (i) shall 
provide the providing Party with notice in writing in accordance with subsection
29.6.6 of this Agreement of its intent to pay the Receipts Tax and (ii) shall 
timely pay the Receipts Tax to the applicable tax authority.

          29.6.3. Taxes Imposed on Customers. With respect to any purchase 
                  --------------------------       
hereunder of services, facilities or arrangements that are resold to a third 
party, if any federal, state or local Tax is imposed by Applicable Law on the 
subscriber, end-user, Customer or ultimate consumer ("Subscriber") in connection
with any such purchase, which a Telecommunications Company is

                                      55

<PAGE>
 
required to impose and/or collect from a Subscriber, then the purchasing Party 
(i) shall be required to impose and/or collect such Tax from the Subscriber and 
(ii) shall timely remit such Tax to the applicable taxing authority.

          29.6.4. Liability for Uncollected Tax, Interest and Penalty. If the 
                  ---------------------------------------------------
providing Party has not received an exemption certificate and fails to collect 
any Tax as required by subsection 29.6.1, then, as between the providing Party 
and the purchasing Party, (i) the purchasing Party shall remain liable for such 
uncollected Tax and (ii) the providing Party shall be liable for any interest 
assessed thereon and any penalty assessed with respect to such uncollected Tax 
by such authority. If the providing Party properly bills the purchasing Party 
for any Tax but the purchasing Party fails to remit such Tax to the providing 
Party as required by subsection 29.6.1, then, as between the providing Party and
the purchasing Party, the purchasing Party shall be liable for such uncollected 
Tax and any interest assessed thereon, as well as any penalty assessed with 
respect to such uncollected Tax by the applicable taxing authority. If the 
providing Party does not collect any Tax as required by subsection 29.6.1 
because the purchasing Party has provided such providing Party with an
exemption certificate that is later found to be inadequate by a taxing
authority, then, as between the providing Party and the purchasing Party, the
purchasing Party shall be liable for such uncollected Tax and any interest
assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. If the purchasing Party
fails to pay the Receipts Tax as required by subsection 29.6.2, then, as between
the providing Party and the purchasing Party, (x) the providing Party shall be
liable for any Tax imposed on its receipts and (y) the purchasing Party shall be
liable for any interest assessed thereon and any penalty assessed upon the
providing Party with respect to such Tax by such authority. If the purchasing
Party fails to impose and/or collect any Tax from Subscribers as required by
subsection 29.6.3, then, as between the providing Party and the purchasing
Party, the purchasing Party shall remain liable for such uncollected Tax and any
interest assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. With respect to any Tax that
the purchasing Party has agreed to pay, or is required to impose on and/or
collect from Subscribers, the purchasing Party agrees to indemnify and hold the
providing Party harmless on an after-tax basis for any costs incurred by the
providing Party as a result of actions taken by the applicable taxing authority
to recover the Tax from the providing Party due to the failure of the purchasing
Party to timely pay, or collect and timely remit, such Tax to such authority. In
the event either Party is audited by a taxing authority, the other Party agrees 
to cooperate fully with the Party being audited in order to respond to any audit
inquiries in a proper and timely manner so that the audit and/or any resulting
controversy may be resolved expeditiously.

          29.6.5. Tax Exemptions and Exemption Certificates. If Applicable Law 
                  -----------------------------------------
clearly exempts a purchase hereunder from a Tax, and if such Law also provides 
an exemption procedure, such as an exemption-certificate requirement, then, if 
the purchasing Party complies with such procedure, the providing Party shall not
collect such Tax during the effective period of such exemption. Such exemption 
shall be effective upon receipt of the exemption certificate or affidavit in 
accordance with the terms set forth in subsection 29.6.6. If Applicable Law 
clearly exempts a purchase hereunder from a Tax, but does not also provide an 
exemption procedure, then the providing Party shall not collect such Tax if the 
purchasing Party (i) furnishes the 

<PAGE>
 
providing Party with a letter signed by an officer requesting such an exemption 
and citing the provision in the Law which clearly allows such exemption and (ii)
supplies the providing Party with an indemnification agreement, reasonably 
acceptable to the providing Party (e.g., an agreement commonly used in the 
industry), which holds the providing Party harmless on an after-tax basis with 
respect to its forbearing to collect such Tax.

          29.6.6.  Notices for Purposes of this Subsection 29.6. All notices, 
                   --------------------------------------------
affidavits, exemption-certificates or other communications required or permitted
to be given by either Party to the other, for purposes of this subsection 29.6, 
shall be made in writing and shall be delivered in person or sent by certified 
mail, return receipt requested, or registered mail, or a courier service 
providing proof of service, and sent to the addresses set forth in subsection 
29.10 as well as to the following:

     To Bell Atlantic:        Tax Administration
                              Bell Atlantic Network Services, Inc.
                              1717 Arch Street
                              30th Floor
                              Philadelphia, PA 19103

     To MFS:                  Corporate Tax Department
                              MFS Communications Company, Inc.
                              11808 Miracle Hills Drive
                              Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addresses 
by giving notice is accordance with the terms of this subsection 29.6. Any 
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT. Neither Party shall assign this Agreement nor any of its 
rights or obligations hereunder without the prior written consent of the other 
Party, which consent shall not be unreasonably withheld. Any assignment or 
delegation in violation of this subsection 29.7 shall be void and ineffective 
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS.

          29.8.1   Except may otherwise be provided in this Agreement, each 
Party shall submit on a monthly basis an itemized statement of charges incurred
by the other Party during the preceding month(s) for services rendered 
hereunder. Payment of billed amounts under this Agreement, whether billed on a 
monthly basis or as otherwise provided herein, shall be due, in immediately 
available U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2   Although it is the intent of both Parties to submit timely 
and accurate statements of charges, failure by either Party to present 
statements to the other Party in a timely manner shall not constitute a breach
or default, or a waiver of the right to payment of the incurred charges, by the
billing Party under this Agreement, and the billed Party shall not be entitled
to

                                      57
<PAGE>
 
dispute the billing Party's statement(s) based on such Party's failure to 
submit them in a timely fashion.

          29.8.3  If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60) days 
of its receipt of the invoice containing such disputed amount give notice to the
Billing Party of the amounts it disputes ("Disputed Amounts") and include in 
such notice the specific details and reasons for disputing each item. The 
Non-Paying Party shall pay when due (i) all undisputed amounts to the Billing 
Party and (ii) all Disputed Amounts into an interest bearing escrow account with
a third party escrow agent mutually agreed upon by the Parties.

          29.8.4  If the Parties are unable to resolve the issues related to the
Disputed Amounts in the normal course of business within ninety (90) days after 
delivery to the Billing Party of notice of the Disputed Amounts, each of the 
Parties shall appoint a designated representative that has authority to settle 
the dispute and that is at a higher level of management than the persons with 
direct responsibility for administration of this Agreement. The designated 
representatives shall meet as often as they reasonably deem necessary in order 
to discuss the dispute and negotiate in good faith in an effort to resolve such 
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

          29.8.5  If the Parties are unable to resolve issues related to the 
Disputed Amounts within forty-five (45) days after the Parties' appointment of 
designated representatives pursuant to subsection 29.8.4, then either Party may 
file a complaint with the Commission to resolve such issues or proceed with any 
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus 
applicable late fees, to be paid to either Party.

          29.8.6  The Parties agrees that all negotiations pursuant to this 
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state 
rules of evidence.

          29.8.7  Any undisputed amounts not paid when due shall accrue interest
from the date such amounts were due at the lesser of (i) one and one-half 
percent (1-1/2%) per month or (ii) the highest rate of interest that may be 
charged under applicable law.

     29.9 DISPUTE RESOLUTION. Any dispute between the Parties regarding the 
interpretation or enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial
forum ofcompetent jurisdiction.

                                      58
<PAGE>
 
     29.10     NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing and shall be (a) delivered personally, (b) 
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by 
telecopy to the following addresses of the Parties:

               To MFS:

               MFS Intelenet of Virginia, Inc.
               33 Whitehall St.
               15/th/ Floor
               New York, NY 10004
               Attn: Director, Regulatory Affairs - Eastern Region
               Facsimile: 212/843-3060

               To Bell Atlantic:

               Director - Interconnection Services
               Bell Atlantic Network Services, Inc.
               1320 N. Courthouse Road
               9th Floor
               Arlington, VA 22201
               Facsimile: 703/974-2183

               with a copy to:

               Vice President and General Counsel
               Bell Atlantic - Virginia, Inc.
               600 East Main Street
               24th Floor
               Richmond, VA 23261
               Facsimile: (804) 772-2143

or to such other address as either Party shall designate by proper notice. 
Notices will be deemed given as of the earlier of (i) the date of actual 
receipt, (ii) the next business day when notice is sent via express mail or 
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of telecopy.

     29.11     SECTION 252(I) OBLIGATIONS

               29.11.1 If, at any time during the term of this Agreement, either
Party enters into an agreement to provide an integrated package of services or 
arrangements substantially similar to that described herein to another CLEC (in 
the case of BA), or another incumbent LEC (in the case of MFS), operating within
the same state to which this Agreement applies, on terms significantly

                                      59
<PAGE>
 
different than those available under this Agreement (the "Other Agreement"), 
then the other Party may opt to adopt, on a prospective basis only, the rates, 
terms, and conditions contained in the Other Agreement (i) in its entirety, or
(ii) that relate directly to any of the following individual services, Network 
Elements, or arrangements, for its own reciprocal arrangements with the first 
Party, including, without limitation, any term or volume commitments or network 
architecture configurations:

          (a)  Unbundled Loop Elements - Section 251(c)(3) of the Act (Section 
     11 of this Agreement); or

          (b)  Collocation - Section 251(c)(6) of the Act (Section 13 of this 
     Agreement); or

          (c)  Number Portability - Section 251(b)(2) of the Act (Section 14 of 
     this Agreement); or

          (d)  Access to Rights of Way - Section 251(b)(4) of the Act (Section 
     16 of this Agreement).

          (e)  transiting arrangements.

          29.11.2  To the extent the exercise of the foregoing options requires 
a rearrangement of facilities by the providing Party, the opting Party shall be 
liable for the non-recurring charges associated therewith.

          29.11.3  The Party electing to exercise such option shall do so by 
delivering written notice to the first Party. Upon receipt of said notice by the
first Party, the Parties shall amend this Agreement to provide the same rates, 
terms and conditions to the notifying Party for the remaining term of this 
Agreement; provided, however, that the Party exercising its option under this 
subsection 29.11 must continue to provide the same services or arrangements to 
the first Party as required by this Agreement, subject either to the rates, 
terms, and conditions applicable to the first Party in its agreement with the 
third party or to the rates, terms, and conditions of this Agreement, whichever 
is more favorable to the first Party in its sole determination.

          29.11.4  BA represents and warrants that, as of the date of this 
Agreement, it has not entered into any comparable Interconnection agreement with
any other CLEC in BA's service territory that is significantly more favorable 
than the terms contained herein. BA makes no warranty or representation with 
respect to its Interconnection arrangements with its affiliates or ITCs.

   29.12  JOINT WORK PRODUCT. This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and
shall be fairly interpreted in accordance with its terms and, in the event of
any ambiguities, no inferences shall be drawn against either Party.
 
                                      60
<PAGE>
 
     29.13   NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. This Agreement
is for the sole benefit of the Parties and their permitted assigns, and nothing
herein express or implied shall create or be construed to create any third-party
beneficiary rights hereunder. Except for provisions herein expressly authorizing
a Party to act for another, nothing in this Agreement shall constitute a Party
as a legal representative or agent of the other Party, nor shall a Party have
the right or authority to assume, create or incur any liability or any
obligation of any kind, express or implied, against or in the name or on behalf
of the other Party unless otherwise expressly permitted by such other Party.
Except as otherwise expressly provided in this Agreement, no Party undertakes to
perform any obligation of the other Party, whether regulatory or contractual, or
to assume any responsibility for the management of the other Party's business.

     29.14   NO LICENSE.

             29.14.1 Nothing in this Agreement shall be construed as the grant
of a license, either express or implied, with respect to any patent, copyright,
trademark, trade name, trade secret or any other proprietary or intellectual
property now or hereafter owned, controlled or licensable by either Party.
Neither Party may use any patent, copyrightable materials, trademark, trade
name, trade secret or other intellectual property right of the other Party
except in accordance with the terms of a separate license agreement between the
Parties granting such rights.

             29.14.2 Neither Party shall have any obligation to defend,
indemnify or hold harmless, or acquire any license or right for the benefit of,
or owe any other obligation or have any liability to, the other Party or its
customers based on or arising from any claim, demand, or proceeding by any third
party alleging or asserting that the use of any circuit, apparatus, or system,
or the use of any software,or the performance of any service or method, or the
provision of any facilities by either Party under this Agreement, alone or in
combination with that of the other Party, constitutes direct, vicarious or
contributory infringement or inducement to infringe, misuse or misappropriation
of any patent, copyright, trademark, trade secret, or any other proprietary or
intellectual property right of any Party or third party. Each Party, however,
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

             29.14.3  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE
PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, ANY
WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15   TECHNOLOGY UPGRADES.  Nothing in this Agreement shall limit BA's
ability to upgrade its network through the incorporation of new equipment, new
software or otherwise. BA shall provide MFS written notice at least ninety (90)
days prior to the incorporation of any such upgrades in BA's network that will
materially affect MFS's service. MFS shall be solely responsible for the cost
and effort of accommodating such changes in its own network.

                                      61

<PAGE>
 
     29.16  SURVIVAL. The Parties' obligations under this Agreement which by 
their nature are intended to continue beyond the termination or expiration of 
this Agreement shall survive the termination or expiration of this Agreement.

     29.17  ENTIRE AGREEMENT. The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other documents or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with respect to the subject matter 
hereof, superseding all prior understandings, proposals and other 
communications, oral or written. Neither Party shall be bound by any preprinted 
terms additional to or different from those in this Agreement that may appear 
subsequently in the other Party's form documents, purchase orders, quotations, 
acknowledgements, invoices or other communications.

     29.18  COUNTERPARTS. This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19  MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No modification, 
amendment, supplement to, or waiver of the Agreement or any of its provisions 
shall be effective and binding upon the Parties unless it is made in writing 
and duly signed by the Parties. A failure or delay of either Party to enforce 
any of the provisions hereof, to exercise any option which is herein provided, 
or to require performance of any of the provisions hereof shall in no way be 
construed to be a waiver of such provisions or options.

     29.20  SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and inure
to the benefit of the Parties and their respective legal successors and 
permitted assigns.

     29.21  PUBLICITY. Neither Party shall use the name of the other Party in 
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      62
<PAGE>
 

          IN WITNESS WHEREOF, the Parties hereto have caused this Agreement
to be executed as of this 16th day of July, 1996.


MFS INTELENET OF                                  BELL ATLANTIC -
VIRGINIA, INC.                                    VIRGINIA, INC.


By: /s/ Alex J Harris                             By: /s/ H.R. Stallard
   ---------------------------------------           -------------------

Printed: Alex J. Harris                           Printed: H.R. STALLARD
        ----------------------------------                -------------- 

Title: Vice President Regulatory Affairs          Title PRES. / CEO - BA-UA 
      ------------------------------------             -----------------

                                      63


<PAGE>
 
SCHEDULE 1.0

CERTAIN TERMS AS DEFINED IN THE ACT, AS OF JULY 16, 1996

     "Dialing Parity" means that a person that is not an affiliate of a local 
exchange carrier is able to provide Telecommunications Services in such a manner
that Customers have the ability to route automatically, without the use of any 
access code, their Telecommunications to the Telecommunications Services 
provider of the customer's designation from among two (2) or more 
Telecommunications Services providers (including such LEC).

     "Exchange Access" means the offering of access to Telephone Exchange 
Services or facilities for the purpose of the origination or termination of 
Telephone Toll Services.

     "InterLATA" means Telecommunications between a point located in a local 
access and transport area and a point located outside such area.

     "Local Access and Transport Area" or "LATA" means a contiguous geographic 
area: (a) established before the date of enactment of the Act by a Bell 
operating company such that no Exchange Area includes points within more than 
one (1) metropolitan statistical area, consolidated metropolitan statistical 
area, or State, except as expressly permitted under the AT&T Consent Decree; or 
(b) established or modified  by a Bell operating company after such date of 
enactment and approved by the FCC.

     "Local Exchange Carrier" means any person that is engaged in the provision 
of Telephone Exchange Service or Exchange Access. Such term does not include a 
person insofar as such person is engaged in the provision of a commercial mobile
service under Section 322(c) of the Act, except to the extent that the FCC finds
that such service should be included in the definition of such term.

     "Network Element" means a facility or equipment used in the provision of a 
Telecommunications Service. Such term also includes features, functions, and 
capabilities that are provided by means of such facility or equipment, including
subscriber numbers, databases, signaling systems, and information sufficient for
billing and collection or used in the transmission, routing, or other provision 
of a Telecommunications Service.

     "Number Portability" means the ability of end users of telecommunications 
services to retain, at the same location, existing telecommunications numbers 
without impairment of quality, reliability, or convenience when switching from 
one telecommunications carrier to another.

     "Telecommunications" means the transmission, between or among points 
specified by the user, of information of the user's choosing, without change in 
the form or content of the information as sent and received.
<PAGE>
 
     "Telecommunications Carrier" means any provider of Telecommunications 
Services, except that such term does not include aggregators of 
Telecommunications Services (as defined in Section 226 of the Communications 
Act).

     "Telecommunications Service" means the offering of Telecommunications for a
fee directly to the public, or to such classes of users as to be effectively 
available directly to the public regardless of the facilities used.

     "Telephone Exchange Service" means (a) service within a telephone exchange 
or within a connected system of telephone exchanges within the same exchange
area operated to furnish subscribers intercommunicating service of the character
ordinarily furnished by a single exchange, and which is covered by the exchange
service charge, or (b) comparable service provided through a system of switches,
transmission equipment, or other facilities (or combination thereof) by which a
subscriber can originate and terminate a telecommunications service.

     "Telephone Toll Service" means telephone service between stations in 
different exchange areas for which there is made a separate charge not included 
in contracts with subscribers for exchange service.

<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA

     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
than the listed Dates.

================================================================================
LATA IN VIRGINIA    MILESTONE                                   DATE
- --------------------------------------------------------------------------------
LATA 236            LATA Start Date ("SD")                      Effective Date
                   -------------------------------------------------------------
                    SS7 Certification, Collocation, and NXX(s)  SD plus 15 days
                    Applied For
                   -------------------------------------------------------------
                    Parties Agree on Initial Network Design     SD plus 30 days
                   -------------------------------------------------------------
                    Valid Access Service Request(s) ("ASRs")    SD plus 45 days
                    and Routing Information Received by BA
                   -------------------------------------------------------------
                    Collocation Arrangements Complete for       SD plus 135 days
                    Trunk Interconnection and IDLC for ULLs
                   -------------------------------------------------------------
                    All Trunks Tested and Turned Up; SS7        SD plus 155 days
                    Certification Achieved; /1/ VG ULL 
                    Capability Available
                   -------------------------------------------------------------
                    Call-through Testing Completed;             SD plus 180 days
                    "Interconnection Activation Date"
================================================================================

     Failure of a Party or the Parties to meet an earlier Milestone Date shall 
not relieve either Party of the responsibility to make its best efforts to meet 
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that, 
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when 
MFS has an effective Tariff for business Telephone Exchange Service in the 
Commonwealth of Virginia and has a significant number of Telephone Exchange 
Service Customer lines in service for business Telephone Exchange Service 
Customers in that LATA in the Commonwealth of Virginia that are not affiliates 
or employees of either BA or MFS, and (ii) residential Telephone Exchange 
Service shall be considered "fully operational" in a LATA in the Commonwealth of
Virginia when MFS has an effective Tariff for residential Telephone Exchange 
Service in the Commonwealth of Virginia and has a significant number of 
Telephone Exchange Service Customer lines in service for residential Telephone 
Exchange Service Customers in that LATA in the COmmonwealth of Virginia that are
not affiliates or employees of either BA or MFS.



___________________
/1/  SS7 certification scheduling depends on actual schedule availability at 
     time of request.

                                       1
<PAGE>
 
SCHEDULE 4

INTERCONNECTION POINTS IN LATA


                                   LATA 236
                                   --------

M-IP:     Reston Switch
          12379 Sunrise Valley Dr.
          Reston, VA

BA-IP     Arlington Tandem
          1025 N. Irving Street
          Arlington, VA
<PAGE>
 
                     SCHEDULE 4.2 - PHYSICAL ARCHITECTURE

                                [Illustrative]


                           [FLOOR PLAN APPEARS HERE]



<PAGE>
 
                      SCHEDULE 4.3 - INITIAL ARCHITECTURE

                                [Illustrative]


     Bell Atlantic Leases MFS-owned Facilities for Delivery of BA Traffic


                           [FLOOR PLAN APPEARS HERE]



               MFS-owned Facilities for Delivery of MFS Traffic

              
<PAGE>
 
SCHEDULE 4.5

INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC

     Each Party shall provide the other Party with Interconnection to its 
network at the following points for transmission, routing and termination. Each 
Party shall make available at its Interconnection Points facilities to route the
traffic it receives to the appropriate final destination. Interconnection at a 
BA-IP that is a Local Serving Wire Center provides access to all of the 
Interconnection Points identified below (except for paragraphs 8 through 11), 
via facilities appropriate for the traffic types and destinations identified 
below. Compensation for such facilities will be as set forth in Exhibit A or as 
provided elsewhere herein.

     1.   For the termination of Local Traffic or Toll Traffic originated by one
Party's Customer and terminated to the other Party's Customer, at the points set
forth in subsections 4.2 and/or 4.3 of the main body of the Agreement.

     2.   For the termination of Meet Point Billing Traffic Traffic from an IXC 
to:

          (a)  MFS, at the M-IP in LATA in which the Traffic is to terminate.

          (b)  BA, at the BA-IP in LATA in which the Traffic is to terminate.

     3.   For the termination of Transit Traffic from an ITC, wireless carrier 
or other CLEC to:

          (a)  MFS, at the M-IP in which the Traffic is to terminate.

          (b)  BA, at the BA-IP in LATA in which the Traffic is to terminate.

     4.   For 911/E911 traffic originated on MFS's network, at the PSAP in areas
where only Basic 911 service is available, or at the BA 911 Tandem Office 
serving the area in which the MFS Customer is located, in accordance with 
applicable state laws and regulations and PSAP requirements.

     5.   For Directory Assistance (411 or NPA-555-1212) traffic, at the
applicable BA Local Serving Wire Center or the BA operator services Tandem
Office subtended by such Local Serving Wire Center.

     6.   For Operator Services (call completion) traffic, at the applicable BA 
Local Serving Wire Center or the BA operator services Tandem Office subtended by
such Local Serving Wire Center.

     7.   For LSV/VCI traffic, at the terminating Party's Local Serving Wire 
Center or operator services Tandem Office subtended by such Local Serving Wire 
Center.
<PAGE>
 
     8.   For SS7 signaling originated by:

          (a)  MFS, at mutually agreed-upon Signaling Point of 
Interconnection(s) ("SPOI") in the LATA in which the Local or Toll Traffic 
originates, over CCSAC links provisioned in accordance with Bellcore GR-905 and 
Bell Atlantic Supplement Common Channel Signaling Network Interface 
Specification (BA_905).

          (b)  BA, at mutually agreed-upon SPOIs in the LATA in which the Local 
or Toll Traffic originates, over a CCSAC links provisioned in accordance with 
Bellcore GR-905 and BA-905.

Alternatively, either Party may elect to interconnect for SS7 signaling through 
a commercial SS7 hub provider.

     9.   For 800/888 database inquiry traffic, at any BA Signaling Transfer 
Point in the LATA in which the originating MFS Wire Center is located, over a 
CCSAC link. Alternatively, MFS may elect to interconnect through a commercial 
SS7 hub provider.

     10.  For Line Information Database ("LIDB") inquiry traffic, at any BA 
Signaling Transfer Point in the LATA in which the LIDB is located, over a CCSAC 
link. Alternatively, MFS may elect to interconnect through a commercial SS7 hub 
provider.

     11.  For any other type of traffic, at reasonable points to be agreed upon 
by the Parties, based on the network architecture of the terminating Party's 
network.

                                       2
<PAGE>
 
SCHEDULE 6.3

RATE ELEMENTS UNDER MEET POINT BILLING

INTERSTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS
- --------------------------------------------------------------------

RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/               
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage 
                                        (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query

INTRASTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS/1/
- -----------------------------------------------------------------------

RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage
                                        (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query


____________________________
/1/  Pending approval of the BA intrastate local transport restructure tariff, 
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

                                       1
<PAGE>
 
SCHEDULE 27.0

PERFORMANCE INTERVAL DATES FOR SPECIFIED 
ACTIVITIES


- --------------------------------------------------------------------------------
          SPECIFIED ACTIVITY                 PERFORMANCE INTERVAL DATE/2/
(I) UNBUNDLE LOCAL LOOP INSTALLATION/1/
    -----------------------------------
- --------------------------------------------------------------------------------
1-10 Loops per service order                 6 business days from BA's receipt 
                                             of valid service order
- --------------------------------------------------------------------------------
11-20 Loops per service order                10 business days from BA's receipt 
                                             of valid service order
- --------------------------------------------------------------------------------
21 + Loops per service order                 To be negotiated on order-by-order
                                             basis
- --------------------------------------------------------------------------------
(II) INTERIM NUMBER PORTABILITY INSTALLATION
     ---------------------------------------
- --------------------------------------------------------------------------------
1-10 Numbers per service order               6 business days from BA's receipt 
                                             of valid service order
- --------------------------------------------------------------------------------
11-20 Numbers per service order              10 business days from BA's receipt 
                                             of valid service order
- --------------------------------------------------------------------------------
21 + Numbers per service order               To be negotiated on order-by-order
                                             basis
- --------------------------------------------------------------------------------
(III) OUT-OF-SERVICE REPAIRS                 Less than 24 hours from BA's
      ----------------------
                                             receipt of notification of out-of-
                                             service condition
- --------------------------------------------------------------------------------

______________________________
/1/  The Unbundled Loop Installation intervals set forth in this Schedule 27.0 
apply only to ULLs offered by BA as of the date of this Agreement. Installation 
intervals for new ULLS will be developed by the Parties as such ULLs become
available.

/2/  Unless otherwise agreed to by the Parties, in which case the Performance 
Interval Date shall be extended until the agreed-upon date. Notwithstanding the 
Performance Interval Dates contained in this Schedule 27.0, under no 
circumstances will BA be obligated to extend installation, provision, or repair 
intervals to MFS that are more favorable than BA extends to its own customers 
for comparable services.

                                       2
<PAGE>
 
SCHEDULE 27.1

MFS SERVICE QUALITY STANDARDS

1.0  UNBUNDLED LOCAL LOOP INSTALLATION ORDERS

1.1  All order information submitted by MFS is valid (e.g. street address, 
floor/unit number, cable pair assignment, etc.).

1.2  Customer (end user) is available at appointed time and day.


2.0  "LIVE" CUTOVER UNBUNDLED LOCAL LOOP INSTALLATION ORDERS (PURSUANT TO 
SECTION 11.6)

2.1  Accurate account and end user information submitted on service request.

2.2  Accurate tie cable and pair assignment provided by MFS on service request.
<PAGE>
 
                                                                       EXHIBIT A

                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.

                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   -------------------------------------

A.   BA SERVICES, FACILITIES, AND ARRANGEMENTS:

- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING            RECURRING
     ----------                    -------------            ---------
- --------------------------------------------------------------------------------
1.a. Entrance facilities, and      Per interstate [BA FCC #1 sec. 6.9.1.] and
     transport, as appropriate     (proposed) intrastate [BA-VA SCC 217 sec. 
     for Interconnection at BA     6.8.2] access tariffs for Feature Group D 
     End Office, Tandem Office,    service/2/
     Serving Wire Center, or 
     other Point of 
     Interconnection

                                   Illustrative:
     
                                     Interstate non-recurring: $1, plus $1 
                                   switched access connection charge per trunk; 
                                   DS-1 entrance facility $210-$212/mo.

                                     Intrastate nonrecurring: $895 for first DS-
                                   1, $280 for additional, plus $25 switched
                                   access connection charge per trunk; DS-1
                                   entrance facility $270/mo.

- --------------------------------------------------------------------------------
1.b. Collocation and related       Per interstate [BA FCC 1 sec. 19] and 
     services for Interconnection  intrastate access tariffs/3/
     at BA End Office, Tandem 
     Office, or Serving Wire 
     Center
- --------------------------------------------------------------------------------

/1/  Rates listed herein for services, facilities, or arrangements that are 
marked with an asterisk (*) are fixed pursuant to Section 20 of the Agreement
for the initial term of the Agreement, as set forth in Section 22 of the
Agreement. Rates for services, facilities, or arrangements that are not marked
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.

/2/  Pending approval of the BA intrastate local transport restructure tariff, 
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

/3/  Pending approval of the BA intrastate collocation tariff to be filed no 
later December 31, 1996, all collocation services shall be charged at rates 
found in BA FCC 1 sec. 19.

                                       1
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING            RECURRING           
     ----------                    -------------            ---------           
- --------------------------------------------------------------------------------
1.c. Tandem transit arrangements   Per tariffs cited in     Per interstate [BA  
     (for Interconnection between  sections 1.a. and 1.b.   FCC 1 sec. 6.9.1.B]
     MFS and carriers other than   above, as applicable;    and (proposed)     
     BA)                           separate trunks          intrastate [BA-VA
                                   required for IXC         SCC 217 sec.       
                                   subtending trunks/4/     6.8.2.B] for tandem
                                                            switching and      
                                                            tandem switched    
                                                            transport, as      
                                                            applicable/5/      
                                                                               
                                                            Illustrative:      
                                                                               
                                                            Interstate,         
                                                            (proposed)         
                                                            intrastate tandem  
                                                            switching          
                                                            $.000999/mou, tandem
                                                            switched transport 
                                                            $.000195/mou plus  
                                                            $.000045/mou/mile   
- --------------------------------------------------------------------------------
1.d. 911 Interconnection           Per tariffs cited in 1.a., 1.b., and 1.c.
                                   above, as applicable, for entrance facility
                                   plus applicable transport, or Collocation
                                   Arrangement at 911 tandem
- --------------------------------------------------------------------------------

/4/  See note 2 above.

/5/  See note 2 above.

                                       2
<PAGE>
 
 
- --------------------------------------------------------------------------------
       BA SERVICE                    NON-RECURRING         RECURRING
       ----------                    -------------         ---------
- --------------------------------------------------------------------------------
1.e.   Directory assistance          Intrastate per        Intrastate per       
       Interconnection               (proposed) BA-VA      (proposed) BA-VA     
                                     SCC 217 sec. 9.6.B    SCC 217 sec. 9.6.B;  
                                     (transport)/6/
                                                           Illustrative:        

                                                             Per call rate      
                                                           $.000092 fixed,      
                                                           $.000021 per mile,   
                                                           $.000462 tandem      
                                                           switching, $.003705  
                                                           interconnection/7/
                                                           
                                     Interstate per BA     Interstate per BA    
                                     FCC 1 sec. 9.6.B      FCC 1 sec. 9.6.B     
                                                           
                                                           Illustrative:        
                                                             
                                                             Per call rate      
                                                           $.000082 fixed,      
                                                           $.000019 per mile,   
                                                           $.000353 tandem      
                                                           switching, $.002311  
                                                           interconnection  
- --------------------------------------------------------------------------------
1.f.   Operator services (call       Per separate contract
       completion) Interconnection
- --------------------------------------------------------------------------------
2.     Unbundled elements            Available as listed herein and in 
                                     interstate and intrastate tariffs, and 
                                     pursuant to Section 11. of the Agreement
- --------------------------------------------------------------------------------
3.     Poles, ducts, conduits, ROW   Per contract rates pursuant to 47 U.S.C. 
                                     sec. 224
                                     
                                     Illustrative:

                                       Duct (Northern Virginia) $4.50/ft/yr.

                                       Pole $4.46/attachment/yr.
- --------------------------------------------------------------------------------

/6/    See note 2 above.

/7/    See note 2 above.

                                       3
<PAGE>
 
<TABLE> 
 
- ------------------------------------------------------------------------------------------------------------------------------------
        BA SERVICE                              NON-RECURRING               RECURRING
        ----------                              -------------               ---------
- ------------------------------------------------------------------------------------------------------------------------------------
<S>     <C>                                     <C>                         <C> 
4.a.    Local loop transmission*                Permanent rates to be       Permanent rates to 
        Unbundled Local Loop Element            determined by               determined by  
        Cross Connection to POTS loop           appropriate arbitral        appropriate arbitral
                                                body. Interim rates         body. Interim rates
                                                will apply until the        will apply until the 
                                                permanent rates are         permanent rates are
                                                determined./8/              determined./9/
- ------------------------------------------------------------------------------------------------------------------------------------
4.b.    Special construction charges            As applicable per BA-VA SCC 203 sec. 2
- ------------------------------------------------------------------------------------------------------------------------------------
4.c     Central office technician charges       Per interstate [BA FCC 1 sec. 13.2 or sec. 19.5] tariff
        (during normal working hours)
- ------------------------------------------------------------------------------------------------------------------------------------
5.a.    Trunk Side local transport
      
        DS-1 transport                          Per interstate [BA FCC 1 sec. 6.9.1.C] and (proposed) intrastate [BA-VA SCC 217
                                                sec. 6.8.2.C] tariffs/10/
 
                                                Illustrative recurring:
                                                  Interstate $60/mo. fixed, $17.70/mile/mo.
                                                  Intrastate $75/mo. fixed, $30/mile/mo.
- ------------------------------------------------------------------------------------------------------------------------------------
5.b.    DS-3 transport                          Tariff reference see 5.a. above.

                                                Illustrative recurring:
                                                 
                                                  Interstate, intrastate $900/mo. fixed, $180/mile/mo.
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 


/8/     Interim rates will be based on the following order of precedence: (i)
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in the
state, (iii) any Commission recommendation, or (iv) mutual agreement of the
Parties.

/9/     See preceding note.

/10/    See note 2 above.

                                       4
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                 NON-RECURRING            RECURRING
     ----------                 -------------            ---------      
- --------------------------------------------------------------------------------
6.   Local switching*

     POTS switch Port           $6/service order plus    $1.50/mo., plus usage
                                $6/Port                  per tariff, minus
                                                         wholesale discount 
                                                         per section 14 below
- --------------------------------------------------------------------------------
7.a. Operator services   
          
     911 service (data entry;   No charge    
     database maintenance)*
- --------------------------------------------------------------------------------
7.b. Directory assistance       Per tariff or separate   Per tariff or separate
                                contract; branding       contract
                                available                
                                                         Illustrative tariff 
                                                         rates:

                                                         Interstate [BA FCC 1
                                                         sec. 9.6], $.275-.288
                                                         per call

                                                         Intrastate (proposed)
                                                         [BA-VA SCC 217
                                                         sec. 9.6.A], $.25 per
                                                         call

                                                         Directory transport
                                                         per section 1.e. above
- --------------------------------------------------------------------------------
7.c  Operator call completion   Per separate contract; branding available
- --------------------------------------------------------------------------------
8.a. White pages directory      $5.00 per primary        No charge
     listings*                  listing per number
- --------------------------------------------------------------------------------
8.b  Books & delivery (annual   No charge for normal numbers of books delivered
     home area directories      to end users; bulk deliveries to CLEC per 
     only)*                     separate arrangement
- --------------------------------------------------------------------------------

                                       5
<PAGE>
 
<TABLE> 
<CAPTION>  
- -----------------------------------------------------------------------------------
     BA SERVICE                          NON-RECURRING        RECURRING
     ----------                          -------------        ---------
- -----------------------------------------------------------------------------------
<S>                                      <C>                  <C>        
8.c.  Additional listings, changes to    Per tariff [BA-VA    Per tariff [BA-VA
     listing, non-listed, non-published, SCC 203 sec. 4]      SCC 203 sec. 4]
     and other extra services 
                                         Illustrative:        Illustrative:
                                          
                                          Additional listing: Additional listing:
                                         $9 residence; $17    $1.12/mo. residence
                                         business             $1.42/mo. business
 
                                          Change to listing:  Non-list:
                                         $9 residence; $17    $1.06/mo. residence
                                         business             or business

                                          Non-list:
                                         $9 residence; $17    Non-published:
                                         business             $1.71/mo. 
                                                              residence
                                                              or business
 
                                          Non-published:
                                         $9 residence; $17
                                         business
- -----------------------------------------------------------------------------------
9.   Access to telephone numbers
     (NXX codes issued per ICCF          No charge
     Code Administration Guidelines)*
- -----------------------------------------------------------------------------------
10.a SS7 Interconnection                 Per interstate [BA   Per interstate [BA
                                         FCC 1 sec. 6.9.1.G]  FCC 1 sec. 6.9.1.L]   
                                         and intrastate [BA-  and intrastate [BA-
                                         VA SCC 217 sec.      VA SCC 217 sec.
                                         6.8.2.C] tariff      6.8.2.G] tariff

                                                              Illustrative:
               
                                                               STP ports,
                                                              $900/mo.;
                              
                                                               STP access,
                                                              $3.50/mile/mo. to
                                                              $5.72/mile/mo.
- -----------------------------------------------------------------------------------
</TABLE> 

                                       6
<PAGE>
 
- ------------------------------------------------------------------------------- 
          BA SERVICE               NON-RECURRING            RECURRING
          ----------               -------------            ---------
- ------------------------------------------------------------------------------- 
 10.b     LIDB Interconnection     Per tariff [BA FCC 1     Per tariff [BA FCC 
                                   sec. 6.9.1M]             1 sec. 6.9.1M]

                                   Illustrative.            Illustrative:

                                    Originating point        Query validation
                                   code, $125               $.04/query

                                                             Query transport
                                                            $.0002/query
- ------------------------------------------------------------------------------- 
 10.c     800/888 data base        No separate charge       Per interstate [BA
          Interconnection          (included in FGD         FCC 1 sec.
                                   trunk and STP links)     6.9.2.A.1], and 
                                                            intrastate [BA-VA 
                                                            SCC 217 sec. 
                                                            6.8.2.K] tariffs

                                                            Illustrative:

                                                             Interstate basic
                                                            query, 
                                                            $.003105/query;
                                                            vertical feature 
                                                            package,
                                                            $.000337/query

                                                             Intrastate basic
                                                            query,
                                                            $.003089/query;
                                                            vertical feature
                                                            package,
                                                            $.000327/query

- ------------------------------------------------------------------------------- 
 11.a     Interim number           service order per        $3/mo. per number
          portability              location $30             for up to 10 paths;
          through co-carrier                                $.40/mo. per
          call forwarding          installation per         additional path
                                   number $35 (unless
                                   installed with unbundled 
                                   loop)

                                   installation per
                                   separate path
                                   arrangement $20
- ------------------------------------------------------------------------------- 
                                                       
                                        7
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                               NON-RECURRING      RECURRING
     ----------                               -------------      --------- 
- --------------------------------------------------------------------------------
 11.b     Access pass-through to number                          In accordance 
         portability purchaser*                                  with section 
                                                                 14.5 of 
                                                                 Agreement.
- --------------------------------------------------------------------------------
 12.     Local dialing parity*                 No charge  
- --------------------------------------------------------------------------------
 13.a    Reciprocal call termination

          Local Traffic delivered to Bell 
         Atlantic Interconnection Point

          First year*                                            $.009/mou 
        ------------------------------------------------------------------------
          After first year*                                      In accordance 
                                                                 with note 13 
                                                                 below
- --------------------------------------------------------------------------------
 13.b     Access charges for termination                         Per interstate 
         of intrastate and interstate Toll                       and intrastate 
         Traffic                                                 access tariffs 
                                                                 (charged in 
                                                                 conjunction
                                                                 with Local
                                                                 Traffic, using
                                                                 PLU and PIU, as
                                                                 appropriate)
- --------------------------------------------------------------------------------
 14.a    Wholesale rates for resale of        Percentage discount from retail 
                                              -------------------------------
         telecommunications services provided tariff/12/
                                              ----------
         to end users*/11/
- --------------------------------------------------------------------------------
 14.b     Individual Case Basis services      No discount 
         and similar single-customer serving
         arrangements; directory assistance
         and operator call completion*
- --------------------------------------------------------------------------------

/11/   Excludes telecommunications services designed primarily for wholesale,
such as switched and special access, and, subject to Section 12 of the
Agreement, the following additional arrangements that are not subject to resale:
limited duration promotional offerings, public coin telephone service, and
technical and market trials. Taxes shall be collected and remitted by the
reseller and BA in accordance with legal requirements and as agreed between the
Parties. Surcharges (e.g., 911, telecommunications relay service, universal
service fund) shall be collected by the reseller and either remitted to the
recipient agency or NECA, or passed through to BA for remittance to the
recipient agency or NECA, as appropriate and agreed between the Parties. End
user common line charges shall be collected by the reseller and remitted to BA.

/12/   Pending establishment of mechanized billing procedures adapted to
resale,the Parties will agree upon a composite "bottom-of-the-bill" discount
that reflects the discounts and exclusions identified herein, and such other
adjustments as the Parties agree.

                                       8
<PAGE>
 
- --------------------------------------------------------------------------------
        BA SERVICE                   NON-RECURRING                RECURRING
        ----------                   -------------                ---------
- --------------------------------------------------------------------------------
 14.c    IntraLATA toll, including   Discount per sections 14.d. and 14.e. below
        discount plans*              applied to composite weighted average toll
                                     rate per minute
- --------------------------------------------------------------------------------
 14.d    Other retail residential    6% discount
         services*
- --------------------------------------------------------------------------------
 14.e    Other retail business       9% discount
         services*
- --------------------------------------------------------------------------------

                                       9
<PAGE>
 
B.   MFS SERVICES, FACILITIES, AND ARRANGEMENTS:

<TABLE> 
<CAPTION> 
- -------------------------------------------------------------------------------------------------
     MFS SERVICE                         NON-RECURRING                  RECURRING
     -----------                         -------------                  ---------
- -------------------------------------------------------------------------------------------------
<S>                                      <C>                            <C> 
1.a. Interim Number Portability                                        
     through co-carrier call                                          
     forwarding*                                                       
                                                                       
     Number portability*                 $30/service order,             $3/mo. for ten paths 
                                         $35/number (not                per number; plus     
                                         ordered with ULL)              $.40/mo. per         
                                                                        additional path
                                         $20 per additional            
                                         path order                    
- -------------------------------------------------------------------------------------------------
1.b  Access pass-through to number                                      In accordance with
     portability purchaser*                                             sec. 14.5 of 
                                                                        Agreement
- -------------------------------------------------------------------------------------------------
2.   Local dialing parity*               No charge                     
- -------------------------------------------------------------------------------------------------
3.a  Reciprocal call termination                                       
                                                                       
     Local Traffic delivered                                         
     to MFS Interconnection Point*                                                            
                                                                       
      First year*                                                       $.009/mou
     --------------------------------------------------------------------------------------------
      After first year*                                                 In accordance with
                                                                        note 13 below
- -------------------------------------------------------------------------------------------------
3.b  Access charges for                                                 Per MFS interstate
     termination of intrastate                                          and intrastate access
     and interstate Toll Traffic                                        rates (charged in
                                                                        conjunction with
                                                                        Local Traffic, using
                                                                        PLU and PIU, as
                                                                        appropriate)
- -------------------------------------------------------------------------------------------------
4.   All other MFS services              Available at MFS tariffed or otherwise  
     available to BA for                 generally available rates, not to exceed BA
     purposes of                         rates for equivalent services available to 
     effectuating local                  MFS                      
     exchange competition                                  
- -------------------------------------------------------------------------------------------------
5.   Other Services                                                    
                                                                        
     Information Service billing fee     No Charge                      $.03 per call
- -------------------------------------------------------------------------------------------------
</TABLE> 
                                      10
<PAGE>
 
13   LOCAL TRAFFIC TERMINATION RATES (AFTER FIRST YEAR)

A.   Charges by BA
     -------------

     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA 
          Access Tandem: $.009 per mou

     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou

     Note: All BA-IPs identified in Schedule 4.0 as of the Effective Date are
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs
     shall be subject to the rate of $.009 per mou.



B.   Charges by MFS
     --------------

1.   Single-tiered interconnection structure:

     MFS's rates for the termination of BA's Local Traffic under the single-
     tiered interconnection structure shall be recalculated once each year on
     each anniversary of the Effective Date (the "Rate Determination Date"). The
     initial Rate Determination Date shall be the first anniversary of the
     Effective Date. The methodology for recalculating the rates is as follows:

          LSWC/Access Tandem Minutes = Total minutes of use of Local Traffic
          delivered by MFS to the BA LSWC or BA Access Tandem for most recent
          billed month.

          End Office Minutes = Total minutes of use Local Traffic delivered by
          MFS directly to the terminating BA End Office for most recent billed
          month.

          Total Minutes = Total minutes of use of Local Traffic delivered by MFS
          to BA for most recent billed month.

          MFS Charge at the M-IP =

          (LSWC/Access Tandem Minutes x $.009) + (End Office Minutes x $.007)
          -------------------------------------------------------------------
                                        Total Minutes

2.   Multiple-tiered interconnection structure (if offered by MFS to any
     carrier)

     (a) Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009

     (b) Local Traffic delivered to terminating MFS End Office/node: $.007

                                      11
<PAGE>
 
C.   Miscellaneous Notes
     -------------------

1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended,
and/or (ii) where the Tandem Office that it subtends is not located within 25
miles of the Tandem Office that is subtended by the terminating End Office, then
such Party shall (x) in addition to paying the LSWC/Access Tandem termination
rate described above, purchase the necessary facilities from the terminating
Party to transport such Traffic to a qualifying LSWC or Access Tandem that is
not subject to either conditions (i) or (ii) above, (y) purchase such other
service(s) as the terminating Party may offer under applicable tariff to remedy
such condition(s), or (z) enter into a new compensation arrangement as the
Parties may agree. Notwithstanding the foregoing, nothing in this Agreement
shall obligate BA to provide switching services at a LSWC when it functions as
such.

2.   In the event the two-tiered rate structure described above is modified 
pursuant to Applicable Law to a single rate structure, BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting
Local Traffic it receives at its LSWC to the first point of switching in its 
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure 
set forth above is intended by the Parties to be a Local Traffic termination 
rate for Interconnection to the M-IP within each LATA that is reciprocal and 
equal to the actual rates that will be charged by BA to MFS under the two-tiered
Local Traffic termination rate structure described above that will apply after 
the first anniversary of the Effective Date. The single MFS termination rate is 
also intended to provide financial incentives to MFS to deliver traffic directly
to BA's terminating End Offices once MFS's traffic volumes reach an appropriate 
threshold. The Parties agree that the Reciprocal Compensation rate(s) set forth 
herein recover a reasonable approximation of each Party's additional costs of 
terminating calls that originate on the network facilities of the other Party.

                                      12
<PAGE>
 
EXHIBIT B

                       NETWORK ELEMENT BONA FIDE REQUEST

     1.   Each Party shall promptly consider and analyze access to a new 
unbundled Network Element with the submission of a Network Element Bona Fide
Request hereunder. The Network Element Bona Fide Request process set forth
herein does not apply to those services requested pursuant to Report & Order and
Notice of Proposed Rulemaking 91-141 (rel. October 19, 1992), Paragraph 259 and
Footnote 603 or subsequent orders.

     2.   A Network Element Bona Fide Request shall be submitted in writing and 
shall include a technical description of each requested Network Element, the 
telecommunications service(s) to be provided by the requesting Party using the 
requested Network Element(s), the means of Interconnection, the number or volume
requested, the locations, and the date(s) such Network Elements are desired. The
requesting Party shall either make a binding commitment to order the Network 
Elements requested in the quantity and within the time frame requested or to pay
the requested Party the costs of processing the Requests.

     3.   The requesting Party may cancel a Network Element Bona Fide Request at
any time, but shall pay the other Party's reasonable and demonstrable costs of 
processing and/or implementing the Network Element Bona Fide Request up to date 
of cancellation.

     4.   Within ten (10) business days of its receipt, the receiving Party 
shall acknowledge receipt of the Network Element Bona Fide Request.

     5.   Except under extraordinary circumstances, within thirty (30) days of 
its receipt of a Network Element Bona Fide Request, the receiving Party shall 
provide to the requesting Party a preliminary analysis of such Network Element 
Bona Fide Request. The preliminary analysis shall confirm that the receiving 
Party will offer access to the Network Element or will provide a detailed 
explanation that access to the Network Element is not technically feasible 
and/or that the request does not qualify as a Network Element that is required 
to be provided under the Act.

     6.   If the receiving Party determines that the Network Element Bona Fide 
Request is technically feasible and otherwise qualifies under the Act, it shall 
promptly proceed with developing the requested Network Element upon receipt of 
written authorization from the requesting Party. When it receives such 
authorization, the receiving Party shall promptly develop the requested 
services, determine their availability, calculate the applicable prices and 
establish installation intervals.

     7.   Unless the Parties otherwise agree, the requested Network Element must
be priced in accordance with Section 252(d)(1) of the Act.

                                       1
<PAGE>
 
     8.   As soon as feasible, but not more than ninety (90) days after its 
receipt of authorization to proceed with developing the requested Network
Element, the receiving Party shall provide to the requesting Party a Network
Element Bona Fide Request quote which will include, at a minimum, a description
of each Network Element, the availability, the applicable rates and the
installation intervals.

     9.   Within thirty (30) days of its receipt of the Network Element Bona 
Fide Request quote, the requesting Party must either confirm its order for the 
requested Network Element pursuant to the Network Element Bona Fide Request 
quote or seek arbitration by the Commission pursuant to Section 252 of the Act.

     10.  If a Party to a Network Element Bona Fide Request believes that the 
other Party is not requesting, negotiating or processing the Network Element 
Bona Fide Request in good faith, or disputes a determination, or price or cost 
quote, or is failing to act in accordance with section 251 of the Act, such 
Party may seek mediation or arbitration by the Commission pursuant to Section 
252 of the Act.

                                       2
<PAGE>
 
EXHIBIT C

                   DIRECTORY ASSISTANCE AND CALL COMPLETION
                              SERVICES AGREEMENT

     THIS AGREEMENT is made, effective this ______ day of _________, 1996, by 
and between BELL ATLANTIC NETWORK SERVICES, INC. (hereinafter referred to as 
"Bell Atlantic"), a Delaware corporation with offices at 13100 Columbia Pike, 
Silver Spring, Atlantic"), a Delaware corporation with offices at 13100 Columbia
Pike, Silver Spring, MD 20904, and _________________________, (hereinafter
referred to as "Carrier"), a _______________ corporation with offices at
__________________________________.


1.   SCOPE AND TERM OF AGREEMENT
     ---------------------------

1.1  SCOPE This Agreement sets forth the terms and conditions which shall govern
the use of and payment for Directory Assistance (DA) Service and IntraLATA Call
Completion Service (hereinafter collectively referred to as "Services") to be
provided by Bell Atlantic, or its affiliated companies, to Carrier. Carrier
shall subscribe to and pay for Services for Carrier's local exchange customers
in the _______________ LATAs.

1.2  TERM The initial term of this Agreement shall commence as of 12:01 a.m. on 
the date first written above and shall expire upon the conclusion of the 
subscription period selected by Carrier in Appendix A. At the end of this 
initial term, this Agreement, including Carrier's subscription to Services, 
shall automatically renew for the same length of time as the initial 
subscription period unless either party provides written notice to the other of 
its intent to terminate at least three (3) months prior to the expiration of the
current term.


2.   DESCRIPTION OF SERVICES
     -----------------------

2.1  DIRECTORY ASSISTANCE (DA) SERVICE

     a. Directory Assistance Service shall consist of 1) directory transport by 
Bell Atlantic from the point of Bell Atlantic's interconnection with Carrier's 
trunks to Bell Atlantic's designated DA locations, and 2) the provision of 
telephone number listings by Bell Atlantic Carrier Call Representatives (CCRs)
in response to calls from Carrier's local exchange customers located in the 
LATAs designated in Section 1.1, at the rates specified in Appendix A.

<PAGE>
 
     b. A maximum of two requests for telephone numbers will be accepted per DA 
call. A "DA call" as used in this Agreement shall mean a call answered by or 
forwarded to Bell Atlantic, regardless of whether a telephone number is 
requested, provided or available. The listings that will be available to 
Carrier's customers are those telephone numbers that are listed in Bell 
Atlantic's DA records for the LATAs or NPAs designated in Section 1.1.

2.2  CONNECT REQUEST(TM) SERVICE

     a) Connect ReQuest(TM) Service is an optional DA call completion service. 
It provides Directory Assistance end users the option of placing a call to a 
requested DA listing without having to hang up and redial. If a caller requests 
two numbers on a DA call, only the second number will be completed using Connect
ReQuest(TM).

     b) Connect ReQuest(TM) requires that the Carrier meet switching, facility, 
and other technical standards as required by Bell Atlantic to provide this 
Service. Bell Atlantic will deliver all Connect ReQuest(TM) calls back to the 
Carrier for completion.

2.3  INTRALATA CALL COMPLETION SERVICE

     a) IntraLATA Call Completion Service consists of the live and automated 
call completion services specified in Appendix B, including the completion of 
collect, card and bill-to-third party calls; busy line verification; customer 
requested interrupt; and other assistance to callers. IntraLATA Call Completion 
Service includes the support of the Bell Atlantic carrier call centers and call 
completion facilities used to provide such services to Carrier.

     b) Bell Atlantic will provide Carrier with unrated records for the call 
completion services provided by Bell Atlantic on behalf of Carrier. The rating, 
billing, and settlement of end-user charges for the calls are the responsibility
of Carrier.

2.4  BRANDING  Branding is a service option that permits the Carrier to deliver 
a customized front end announcement to its callers, identifying the Carrier as 
the customer service provider. Branding is available for DA as well as Call 
Completion Services. Carrier shall provide the information required by Bell 
Atlantic to create this announcement. Branding also requires that the Carrier 
maintain dedicated trunking arrangements to the designated Bell Atlantic DA or 
operator switch location.

2.5  CARRIER SUBSCRIPTION SELECTION FORM  The specific Services to which Carrier
shall subscribe and the applicable service subscription periods are contained in
Appendix A ("Carrier Subscription Selection Form").

3.   COMMENCEMENT AND IMPLEMENTATION OF SERVICE
     ------------------------------------------

                                       2

<PAGE>
 

3.1  TECHNICAL QUESTIONNAIRE  Each party shall make good-faith efforts to carry 
out its respective responsibilities in meeting a jointly established schedule 
for implementation. All records and other required information specified in 
Appendix C will be furnished by Carrier at least sixty (60) days prior to the 
commencement of Services (i.e., the cutover date described in Section 3.2.) 
Notices of any changes, additions, or deletions to such records and information 
shall be provided promptly in writing by Carrier to Bell Atlantic.

3.2  CUTOVER  The cutover date for a selected Services shall be the date on 
which such Service shall be available to all of Carrier's local exchange 
customers in the LATAs designated in Section 1.1. The subscription term set 
forth in Appendix A for such Services shall commence on the cutover date.

3.3  SERVICE REVIEW MEETINGS  Bell Atlantic will meet and confer with Carrier 
during the term of this Agreement to review and discuss the Services provided 
under this Agreement. The times for meetings will be established by mutual 
agreement of the parties.

4.   EQUIPMENT AND FACILITIES
     ------------------------

4.1  BELL ATLANTIC will establish and maintain such access equipment and related
facilities for its Carrier Call Centers as may be necessary to perform the 
Services specified in Appendix A, provided that Carrier furnishes Bell Atlantic 
the information specified in Appendix C and any changes in such information in a
timely and accurate manner. Any additional Services that Carrier seeks during 
the term of this Agreement will be subject to mutual agreement and availability 
of facilities and equipment.

4.2  CARRIER will provide and maintain such equipment within its premises as is 
necessary to permit the Bell Atlantic to perform the agreed upon Services in 
accordance with Bell Atlantic standard equipment operation and traffic 
operation procedures.

4.3  CARRIER TRANSPORT AND SWITCHED ACCESS CONNECTION

     a)   Carrier shall, at its expense, arrange for and establish the trunking
and other transport, interface, and signaling arrangements required for Bell
Atlantic to provide Services to Carrier. Separate dedicated trunks for each NPA
or LATA may be required. Any trunks or other transport and access that Carrier
obtains from Bell Atlantic to deliver Carrier's calls to Bell Atlantic shall be
provided pursuant to the applicable tariffs, and not under this Agreement. Bell
Atlantic agrees to coordinate the scheduling of Services to be provided under
this Agreement with the scheduling of any trunking or related services
provisioned by Bell Atlantic under this tariffs.

                                       3

<PAGE>
 
     b)   Carrier shall specify the number of trunks required for Services. For 
Directory Assistance Service, Carrier must provide Feature Group D (FGD) trunks 
directly to the location designated by Bell Atlantic. For IntraLATA Call
Completion Service, Carrier must provide trunks with operator services signaling
directly to the location designated by Bell Atlantic. Bell Atlantic shall
provide Carrier at least three (3) months advance notice in the event of any
change in designated locations.

5.   PAYMENT FOR SERVICES
     --------------------

5.1  RATES  Carrier agrees to pay for Services at the rates contained in 
Appendix A.

5.2  SETTLEMENTS  Carrier shall render payment to Bell Atlantic net thirty (30)
calendar days from the date of delivery of the Service or from the date of 
billing for the Service, whichever occurs later. Carrier shall pay interest on 
any amount overdue at the rate of fifteen (15) percent per annum.

5.2  TAXES  The rates specified in this Agreement and Appendices are exclusive 
of all taxes, duties or similar charges imposed by law. Carrier shall be liable 
for and shall reimburse Bell Atlantic for any sales, use, excise or other taxes 
applicable to the services performed under this Agreement.

5.4  LIQUIDATED DAMAGES  In the event that Carrier discontinues using Bell 
Atlantic's Services in whole or in part, or terminates this agreement prior to 
the expiration of the subscription term, the parties agree the Bell Atlantic 
will incur expenses and damages that will be difficult to calculate. Therefore, 
the parties agree that in the event of such discontinuance or termination, 
Carrier shall pay an amount equal to the charges billed for the month in which 
the highest usage of Services occurred, multiplied by the number of months 
remaining in the then-current term, or b) the sum of $100,000, whichever is 
greater. If Carrier causes this Agreement to terminate before the commencement 
of any Service selected in Appendix A, Carrier shall pay for all costs already 
incurred by Bell Atlantic in establishing and preparing for the commencement of
such Service or the sum of $100,000, whichever is greater.

5.5  CARRIER'S CUSTOMERS  Carrier shall be responsible for all contacts and 
arrangements with its customers concerning the provision and maintenance, and 
the billing and collection, of charges for Services furnished to Carrier's 
customers.

6.   LIMITATION OF LIABILITY
     -----------------------

6.1  DIRECT DAMAGES  In the event that Bell Atlantic, through negligence or 
willful misconduct, fails to provide the Services selected and contracted for 
under this Agreement, Bell Atlantic shall be liable to Carrier for Carrier's 
direct damages resulting from such failure, up to an amount not to exceed the 
payment of charges under this Agreement for the Services affected.

                                       4
<PAGE>
 
6.2  OTHER REMEDIES  THE EXTENT OF BELL ATLANTIC'S LIABILITY ARISING UNDER THIS 
AGREEMENT SHALL BE LIMITED AS DESCRIBED IN PARAGRAPH 6.1 ABOVE. IN NO EVENT 
SHALL BELL ATLANTIC BE LIABLE FOR ANY OTHER LOSS, COST, CLAIM, INJURY, 
LIABILITY, OR EXPENSE RELATED TO OR ARISING OUT OF THIS AGREEMENT OR THE 
SERVICES PROVIDED HEREUNDER INCLUDING, BUT NOT LIMITED TO, ANY INCIDENTAL, 
SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS 
OF REVENUE OR PROFIT, WHETHER RECOVERY IS SOUGHT IN TORT, CONTRACT, OR 
OTHERWISE, EVEN IF BELL ATLANTIC HAD NOTICE OF SUCH DAMAGES.

7.   DEFAULTS AND TERMINATION
     ------------------------

7.1  DEFAULTS OR VIOLATIONS    If Carrier defaults in the payment of any amount 
due hereunder, or if Bell Atlantic fails to provide Services as agreed 
hereunder, and such default or failure shall continue for thirty (30) days after
written notice thereof, the other company may terminate this agreement with 
seven (7) days written notice.

8.   CONFIDENTIAL INFORMATION
     -------------------------

8.1  CONFIDENTIALITY    The parties agree that all confidential and proprietary
information that is marked as specified in Section 8.2 and that is disclosed by
either party to the other party for the purposes of this Agreement, including
rates and terms, shall be treated as confidential unless a) such information was
previously or becomes known to the receiving party free of any obligation to
keep it confidential, b) has been or is subsequently made public by the
disclosing party, or c) is required to be disclosed by law. The receiving party
shall not, except in the performance of the Services under this Agreement or
with the express prior written consent of the other party, disclose or permit
access to any confidential information to any other parties.  The parties
agree to advise their respective employees, agents and representatives to take
such action as may be advisable to preserve and protect the confidentiality of
such information.

8.2  MARKING OF CONFIDENTIAL INFORMATION    All information the disclosing party
considers proprietary or confidential, if in writing or other tangible form, 
shall be conspicuously labeled or marked as "Proprietary" or "Confidential" 
and, if oral, shall be identified as proprietary at the time of disclosure and 
promptly confirmed in writing. Either party shall have the right to correct any 
inadvertent failure to designate information as proprietary by written 
notification within ten (10) days following disclosure.

9.   RELATIONSHIP OF THE PARTIES
     ---------------------------

9.1  INDEPENDENT CONTRACTORS    Bell Atlantic and Carrier shall be independent
contractors under this Agreement and all services under this Agreement shall be
performed by Bell Atlantic as an independent contractor and not as an agent of
Carrier.

<PAGE>
 
9.2    RESPONSIBILITY FOR EMPLOYEES AND AGENTS  All persons furnished by Bell 
Atlantic shall be considered solely Bell Atlantic's employees or agents, and 
Bell Atlantic shall be responsible for compliance with all laws, rules, and 
regulations relating to such persons including, but not limited to, hours of 
labor, working conditions, workers' compensation, payment of wages, benefits, 
unemployment, social security and other payroll taxes. Each party's employees 
and agents, while on premises of the other, shall comply with all rules and 
regulations, including any applicable security procedures and safeguarding of 
confidential data.

10.  GENERAL CONDITIONS
     ------------------

10.1   ASSIGNMENT  Neither party may assign or delegate its rights and
obligations under this Agreement without the prior written consent of the other
party except that Bell Atlantic may assign this Agreement to an affiliate or
subsidiary without such consent.

10.2   CHOICE OF LAW  The validity, construction and performance of this
Agreement shall be governed by the laws of _________________.

10.3   COMPLIANCE WITH LAWS  Each party shall comply with all applicable
federal, state, county and local laws, ordinances, regulation, rules and codes
in the performance of this Agreement. Neither party shall be liable to the other
for termination of this Agreement or any services to be provided hereunder
necessitated by compliance with any law, rule, regulation or court order of a
duly authorized governmental body.

10.4   CONTINGENCY  Neither party shall be held responsible or liable to the
other for any delay or failure in performance caused by fires, strikes,
embargoes, requirements imposed by Government regulation, civil or military
authorities, act of God or by the public enemy, or other causes beyond the
control of Carrier or Bell Atlantic. If such a contingency occurs, the party
injured by the other's inability to perform may: a) terminate the affected
services or part thereof not already rendered; or b) suspend the affected
services or part thereof for the duration of the delaying cause and resume
performance once the delaying causes cease.

10.5   LICENSES  No licenses, expressed or implied, under any patents,
copyrights, trademarks or other intellectual property rights are granted by Bell
Atlantic to Carrier under this Agreement.

10.6   NOTICES Except as otherwise specified in this Agreement, any notice
required or permitted under this Agreement shall be in writing and shall be
given to the other party at the address designated below by hand delivery,
registered return-receipt requested mail, confirmed facsimile, or nationally
recognized courier service.

                                       6

<PAGE>
 
          For Bell Atlantic:  Bell Atlantic Network Services, Inc.
                              13100 Columbia Pike, D39
                              Silver Spring, MD 20904
                              Attn:______________, Product Manager


          For Carrier:



The above addresses may be changed by giving thirty (30) calendar days prior 
written notice as prescribed above. Notice shall be deemed to have been given or
made on the date of delivery if received by hand, facsimile or express courier, 
and three days after delivery to the U.S. Postal Service, if mailed.

10.7   PUBLICITY   Bell Atlantic and Carrier agree to submit to each other prior
to publication all advertising, sales promotions, press releases and other
publicity matters containing or mentioning a) the services performed by Bell
Atlantic under this Agreement, b) either party's name or marks, or c) language
from which either party's names or marks may be inferred or implied. Bell
Atlantic and Carrier further agree not to publish or use any such advertising,
sales promotions, press releases, or publicity matters unless it obtains the
other party's prior written consent.

10.8   SEVERABILITY   If any provision of this Agreement or the application of 
any provision shall be held by a tribunal of competent jurisdiction to be 
contrary to law or unenforceable, the remaining provisions of this Agreement 
shall continue in full force and effect.

10.9   SURVIVAL   All obligations hereunder, incurred by either Bell Atlantic or
Carrier prior to the cancellation, termination or expiration of this Agreement 
shall survive such cancellation, termination or expiration.

10.10  CAPTIONS AND SECTION HEADINGS   The captions and section headings in this
Agreement are for convenience only and do not affect the meaning or
interpretation of this Agreement.

10.11  DUPLICATE ORIGINALS   This Agreement may be executed separately by the 
parties in one or more counterparts. Each duplicate executed shall be deemed an 
original, and all together shall constitute one and the same document.

10.12  NONDISCLOSURE OF AGREEMENT   Each party agrees not to disclose the terms
and conditions of this Agreement to any third party, except that it shall not be
deemed a breach of this provision for the parties to disclose the terms and
conditions of this

<PAGE>
 
Agreement to their respective subsidiaries and affiliated companies or to any 
duly constituted governmental body which requires disclosure.

10.13  ENTIRE AGREEMENT  The terms and conditions of this Agreement, including 
Appendices A, B, and C, attached to this Agreement, constitute the entire 
Agreement between Bell Atlantic and Carrier relating to the subject matter of 
this Agreement, and supersede any and all prior or contemporaneous 
understandings, promises or representations, whether written or oral, between 
the parties relating to the subject matter of this Agreement. Any waiver, 
modification or amendment of any provision of this Agreement, or of any right or
remedy hereunder, shall not be effective unless made in writing and signed by 
both parties.


IN WITNESS WHEREOF, the parties agree that the effective date of this Agreement
is the date first written above, and each party warrants that it has caused this
Agreement to be signed and delivered by its duly authorized representative.


BELL ATLANTIC
NETWORK SERVICES, INC.

Name:_____________________________           Name:_____________________________
                                             
Title:____________________________           Title:____________________________
                                             
Signature:________________________           Signature:________________________
                                             
Date:_____________________________           Date:_____________________________ 

                                       8

<PAGE>
 
                                                                      APPENDIX A

                      CARRIER SUBSCRIPTION SELECTION FORM
                      -----------------------------------

- ------------------------------------------------------------------------
 CONTRACT DA SERVICE                  SUBSCRIPTION       RATE PER
 SELECTED                             PERIOD             CALL
- ------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - STANDARD           YEAR(S)
- ------------------------------------------------------------------------ 
 DIRECTORY ASSISTANCE - STANDARD WITH      
 FRONT END BRANDING*                       YEAR(S) 
- ------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE      YEAR(S) 
- ------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE
 WITH FRONT END BRANDING*                  YEAR(S) 
- ------------------------------------------------------------------------
 DIRECTORY ASSISTANCE CALL COMPLETION      YEAR(S) 
- ------------------------------------------------------------------------
 INTRALATA CALL COMPLETION                 YEAR(S)       SEE RATES BELOW   
- ------------------------------------------------------------------------
 BRANDED INTRALATA CALL COMPLETION*        YEAR(S)       SEE RATES BELOW   
- ------------------------------------------------------------------------
 * PLUS NONRECURRING BRANDING FEE OF $__________.


For informational purposes, the following are the charges for Directory
Transport to be provided under the applicable tariffs. (Call miles are measured
from the BA Wire Center serving Carrier's premises to the DA location):

         Call Miles                          Rate Per Call
         ----------                          -------------
         0 to 1 mile.......................  $0.0014  
         ** 1 to 4 miles...................   0.0015
         ** 4 to 8 miles...................   0.0016
         ** 8 to 16 miles..................   0.0018
         ** 16 to 25 miles.................   0.0018    
         ** 25 to 50 miles.................   0.0019
         ** 50 to 200 miles................   0.0020
         
         ** More than.

- --------------------------------------------------------------------------------
                             CALL COMPLETION RATES
- --------------------------------------------------------------------------------
 TOTAL ANNUAL CALL VOLUME     AUTO    AUTO COLLECT/     LIVE CCR HANDLED
 (ALL CALLS)                PER CALL  THIRD (PER CALL)  PER CCR WORK SECOND
- --------------------------------------------------------------------------------
 0 - 20,000
- --------------------------------------------------------------------------------
 20,001 - 100,000
- --------------------------------------------------------------------------------
 100,001 +
- --------------------------------------------------------------------------------
 Notes:  1) Trunking and switched access costs are not included in the above DA 
 -----    
            and Call Completion rates.
         2) Rates for automated IntraLATA Call Completion calls are based on
            call attempts.

 _________________________                     _________________________
 SIGNATURE (BELL ATLANTIC)                     SIGNATURE(CARRIER)  
<PAGE>
 
                           BELL ATLANTIC RATE SHEET

              VIRGINIA LOCAL EXCHANGE CARRIER DIRECTORY ASSISTANCE


   DIRECTORY ASSISTANCE CALL CHARGE (PER CALL, BASED ON LENGTH OF CONTRACT)

 Type of Service                          Month-to-Month   1-year      3-year
 ---------------                          --------------   ------      ------

- --------------------------------------------------------------------------------
 Standard                                 $.275            $.25        $.23
- --------------------------------------------------------------------------------
 Standard w/Customized Branding*           .278             .253        .233
- --------------------------------------------------------------------------------
 Live Carrier Call Representative (CCR)    .285             .26         .24
- --------------------------------------------------------------------------------
 Live CCR w/Customized Branding*           .288             .263        .243
- --------------------------------------------------------------------------------

 * Customized branding fee (non-recurring charge):  $6,000


     CONNECT REQUEST(TM) DIRECTORY ASSISTANCE CALL COMPLETION (OPTIONAL)

- --------------------------------------------------------------------------------
 Charge per Request (in addition to above $.27             $.25        $.22
 charges)
- --------------------------------------------------------------------------------


                          DIRECTORY TRANSPORT CHARGE

(For each call to Directory Assistance service; call miles measured from the 
wire center serving the customer's premises to the DA location).

        Call Miles                          Rate Per Call
        ----------                          -------------

        0 to 8............................  $0.0037
        ** 8 to 13........................   0.0062
        ** 13 to 18.......................   0.0076
        ** 18 to 23.......................   0.0089
        ** 23 to 28.......................   0.0137
        ** 28 miles.......................   0.0223

** More than.



Trunk installation charges are not included.


<PAGE>
 
                                                            [LOGO] BELL ATLANTIC

                            PROPOSED PRICING TERMS

                      INTRALATA CALL COMPLETION SERVICES

                      COMPETITIVE LOCAL EXCHANGE CARRIERS

                        (Prices effective June 1, 1996)

<TABLE> 
<CAPTION>           
- ------------------------------------------------------------------------------------------------------------------------------------
                              TWO YEAR TERM                        THREE YEAR TERM                       FIVE YEAR TERM
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL ANNUAL        AUTO         AUTO        OPERATOR       AUTO        AUTO        OPERATOR       AUTO        AUTO       OPERATOR
CALL VOLUME         CARD         COLLECT/    HANDLED        CARD        COLLECT/    HANDLED        CARD        COLLECT/   HANDLED
(all calls)         (per call)   THIRD       (per OWS)      (per call)  THIRD       (per OWS)      (per call)  THIRD      (per OWS)
                                 (per call)                             (per call)                             (per call)
- ------------------------------------------------------------------------------------------------------------------------------------
<S>                 <C>          <C>         <C>            <C>         <C>         <C>            <C>         <C>        <C>  
0 - 20,000          $0.15        $0.20       $0.0145        $0.14       $0.19       $0.0141        $0.13       $0.18      $0.0136

- ------------------------------------------------------------------------------------------------------------------------------------

20,001 - 100,000    $0.14        $0.19       $0.0141        $0.13       $0.18       $0.0136        $0.12       $0.17      $0.0131

- ------------------------------------------------------------------------------------------------------------------------------------

100,001 +           $0.13        $0.18       $0.0136        $0.12       $0.17       $0.0131        $0.11       $0.16      $0.0126

- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 

Notes:    Trunking costs are not included in the above rates.
          The rates quoted above for automated calls are based on call attempts.
          All prices include company specific branding.




                            PROPRIETARY INFORMATION
                NOT FOR USE OR DISCLOSURE OUTSIDE BELL ATLANTIC
                        EXCEPT UNDER WRITTEN AGREEMENT.

<PAGE>
 
                                                                      APPENDIX B

                      INTRALATA CALL COMPLETION SERVICES
                      ---------------------------------- 

A.   Calling Card 
     ------------
     Bell Atlantic Carrier Call Representative keys the calling card number and
     call details into the system, secures validation, and releases the call
     into the network.

B.   Collect
     -------
     Bell Atlantic Carrier Call Representative obtains the calling party's name,
     keys the call details if necessary, announces the call to the called party,
     waits for acceptance, and releases the call into the network.

C.   Billed To A Third Party
     -----------------------
     Bell Atlantic Carrier Call Representative requests the calling party's
     name, keys the call details if necessary, calls the third party to verify
     acceptance of billing, and releases the call once acceptance is given.

D.   Assistance - Other
     ------------------
     Bell Atlantic Carrier Call Representative will dial a called number for the
     customer for any of the following reasons:
     
     1. Customer encounters trouble such as wrong number, poor transmission or 
     cutoff, and requests a credit or reconnection.

     2. Customer desires time and charges at the end of conversation.

     3. Customer requires dialing assistance due to a disability..

     4. Customer is unwilling to dial call.

E.   Person-to-Person
     ----------------
     Bell Atlantic Carrier Call Representative requests the person or department
     the calling party has specified, ensures appropriate party has been
     reached (person or department), and releases call.

F.   Busy-Line Verification
     ----------------------
     Bell Atlantic Carrier Call Representative determines if the number
     specified by the customer is in use, idle, or out of order.

G.   Customer-Requested Interrupt 
     ----------------------------

                                      10
<PAGE>
 
     At the customer's request, Bell Atlantic Carrier Call Representative will
     interrupt conversation in progress on a line that has been verified in use.

                                                            APPENDIX B (CONT'D)

H.   Assistance (0-)
     ---------------
     Bell Atlantic Carrier Call Representative will provide customer dialing 
     instructions, assistance with emergency calls, area code information, and 
     business office or repair service.

I.   Validation Services  
     -------------------
     Bell Atlantic will launch a query for the validation of all calling card
     calls, collect calls, billed-to-third number calls and public telephone
     checks to a Line Information Data Base (LIDB). The query costs for query of
     the Bell Atlantic LIDB are included in Bell Atlantic Carrier Call
     Representative (CCR) Work Second or Automated call rate specified in
     Appendix A. Bell Atlantic will also launch queries as stated for
     validations to other companies' LIDBs.

<PAGE>
 
                                                                      APPENDIX C


                            EXCHANGE OF INFORMATION
                            -----------------------

Technical information will be furnished via the use of a Technical Questionnaire
to be provided by Bell Atlantic. Such information will include, but not be 
limited to, the following:

1.   Central Office Exchange Names
2.   Usage Forecasts
3.   Local Central Office Characteristics
4.   Trunking Arrangements and Trunk Group Types
5.   Emergency Reporting System and Procedures
6.   Business Office Information
7.   Repair Service Information
8.   Name and Address Request Information
9.   Tariffs and Rate Information
10.  Customer Dialing Capabilities
11.  Access to EMI Records

                                      12













<PAGE>
 
                                AMENDMENT NO.2

                                    to the

                           INTERCONNECTION AGREEMENT

                                    between

                         BELL ATLANTIC-VIRGINIA, INC.

                                      and

                        MFS INTELENET OF VIRGINIA, INC.

     This Amendment No. 2 is made this 29th day of July, 1997, by and between 
Bell Atlantic-Virginia, Inc. ("BA"), a Virginia corporation with offices at 600
East Main Street, Richmond, Virginia 23219, and MFS Intelenet of Virginia, Inc. 
("MFS"), a Delaware corporation with offices at 33 Whitehall Street, 15th 
Floor, New York, New York 10004. (BA and MFS may be referred to individually as 
a "Party" and collectively as the "Parties").

                                  WITNESSETH:
                                  ----------

     WHEREAS, BA and MFS are Parties to an Interconnection Agreement under 
Sections 251 and 252 of the Telecommunications Act of 1996 dated effective as of
July 16, 1996 (the "Agreement"); and
     
     WHEREAS, the Parties now desire to amend the Agreement to reflect the 
agreement between the Parties to permit MFS, pursuant to Section 251(c)(4) of 
the Communications Act of 1934, to purchase retail telecommunications services 
from BA for resale by MFS in the State of Virginia;

     NOW, THEREFORE, in consideration of the promises and mutual agreements 
herein contained, the Parties agree to amend the Agreement as follows:

     1.   Remove the existing cover page through page 64 of the Agreement and
     insert the attached revised cover page through page 63 of the Agreement,
     which includes deletion of the existing Section 12.0. Resale, in its
     entirety, and insertion of a revised Section 12.0, Resale, in its entirety.

     2.   Insert a new Schedule 12.3. Support Services for Resale, as attached 
     hereto.

                                       1
<PAGE>
 
     3.   Delete the existing Exhibit A and insert the revised Exhibit A, as
     attached hereto.

     4.   Except for the foregoing, the substantive terms and provisions
     contained in the Agreement shall remain in full force and effect.

     This Amendment may be executed in counterparts, each of which shall be
deemed an original and all of which together shall constitute one and the same
instrument.



                          [Intentionally Left Blank]

                                       2
<PAGE>
 
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be 
duly executed as of the date first set forth above.

MFS INTELENET OF                             BELL ATLANTIC
 VIRGINIA, INC.                               VIRGINIA, INC.



By:________________________                  By: /s/ H. R. Stallard
                                                --------------------------

Printed:___________________                  Printed: H. R. Stallard
                                                     ---------------------

Title:_____________________                  Title: President and CEO
                                                   -----------------------

                                       3
<PAGE>
 

         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996


                           DATED AS OF JULY 16, 1996


                                BY AND BETWEEN


                         BELL ATLANTIC-VIRGINIA, INC.

                                      AND

                        MFS INTELENET OF VIRGINIA, INC.
<PAGE>
 
                              TABLE OF CONTENTS
                              -----------------

<TABLE> 
<CAPTION> 
                                                                 Page
                                                                 ----
<S>                                                              <C> 
1.0  DEFINITIONS                                                   2
                                                                 
2.0  INTERPRETATION AND CONSTRUCTION                              10
                                                                 
3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION         
     SCHEDULE                                                     11
                                                                 
4.0  INTERCONNECTION PURSUANT TO SECTION 251(C)(2)                11
4.1  Scope                                                        12
4.2  Physical Architecture                                        13
4.3  Initial Architecture                                         13
4.4  Interconnection in Additional LATAs                          14
4.5  Interconnection Points for Different Types of Traffic        15

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE
     TRAFFIC PURSUANT TO SECTION 251(c)(2)                        15
5.1  Scope of Traffic                                             15
5.2  Trunk Group Connections and Ordering                         15
5.3  Additional Switching System Hierarchy and Trunking           
     Requirements                                                 15
5.4  Signaling                                                    16
5.5  Grades of Service                                            16
5.6  Measurement and Billing                                      16
5.7  Reciprocal Compensation Arrangements--Section 251(b)(5)      17

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC
     PURSUANT TO 251(c)(2)                                        18
6.1  Scope of Traffic                                             18
6.2  Trunk Group Architecture and Traffic Routing                 18
6.3  Meet-Point Billing Arrangements                              19
6.4  800/888 Traffic                                              21

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC          22
7.1  Information Services Traffic                                 22
7.2  LSV/VCI Traffic                                              23
7.3  Transit Service                                              24
7.4  911 E911 Arrangements                                        25
7.5  Ancillary Traffic Generally                                  26

8.0  NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS            26
</TABLE> 

<PAGE>
 
<TABLE> 
<S>                                                                                 <C>  
9.0    NETWORK MAINTENANCE AND MANAGEMENT: OUTAGES                                  26
                                                                                      
9.3    Interference or Impairment                                                   28
9.4    Repeated or Willful Noncompliance                                            28
9.5    Outage Repair Standard                                                       28
9.6    Notice of Changes -- Section 251(c)(5)                                       28
                                                                                      
10.0   JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND INSTALLATION, 
       MAINTENANCE, TESTING AND REPAIR                                              28
10.1   Joint Network Reconfiguration and Grooming Plan                              28
10.2   Installation, Maintenance, Testing and Repair                                29
10.3   Forecasting Requirements for Trunk Provisioning                              29
                                                                                      
11.0   UNBUNDLED ACCESS -- SECTION 251(c)(3)                                        30
11.1   Unbundled Local Loop (ULL) Transmission Types                                30
11.2   Port Types                                                                   31
11.3   Trunk Side Local Transport                                                   32
11.4   Limitations on Unbundled Access                                              32
11.5   Availability of Other Network Elements on an Unbundled Basis                 33
11.6   Provisioning of Unbundled Local Loops                                        33
11.7   Maintenance of Unbundled Local Loops                                         35
11.8   Rates and Charges                                                            35
                                                                                      
12.0   RESALE -- SECTIONS 251(c)(4) and 251(b)(1)                                   35
12.1   Availability of Retail Rates for Resale                                      35
12.2   Availability of Wholesale Rates for Resale                                   35
12.3   Availability of Support Services and Branding for Resale                     35
12.4   Additional Terms Governing Resale and Use of BA Services                     35
                                                                                      
13.0   COLLOCATION -- SECTION 251(c)(6)                                             36
                                                                                      
14.0   NUMBER PORTABILITY -- SECTION 251(b)(2)                                      37
14.1   Scope                                                                        37
14.2   Procedures for Providing INP Through Remote Call Forwarding                  38
14.3   Procedures for Providing INP Through Direct Inward Dial Trunks (Flex-DID)    39
14.4   Procedures for Providing LTNP Through Full NXX Code Migration                39
14.5   Receipt of Terminating Compensation on Traffic to INP'ed Numbers             39
14.6   Recovery of INP Costs Pursuant to FCC Order and Rulemaking                   40
                                                                                  
15.0   DIALING PARITY -- SECTION 251(b)(3)                                          41
                                                                                  
16.0   ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                                 41
</TABLE> 

                                      ii
<PAGE>
 
17.0 DATABASES AND SIGNALING                                                  41

18.0 COORDINATED SERVICE ARRANGEMENTS                                         42
18.1 Intercept and Referral Announcements                                     42
18.2 Coordinated Repair Calls                                                 43
18.3 Customer Authorization                                                   43

19.0 DIRECTORY SERVICES ARRANGEMENTS                                          43
19.1 Directory Listings and Directory Distributions                           44
19.2 Yellow Page Maintenance                                                  45
19.3 Service Information Pages                                                45
19.4 Directory Assistance (DA): Call Completion                               46

20.0 COORDINATION WITH TARIFF TERMS                                           45

21.0 INSURANCE                                                                46

22.0 TERM AND TERMINATION                                                     47

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                             48

24.0 CANCELLATION CHARGES                                                     48

25.0 INDEMNIFICATION                                                          48

26.0 LIMITATION OF LIABILITY                                                  49

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                           50
27.1 Certain Definitions                                                      50
27.2 Performance Standards                                                    51
27.3 Limitations                                                              51
27.4 Service Quality Standards                                                52
27.5 Records                                                                  52

28.0 COMPLIANCE WITH LAWS: REGULATORY APPROVAL                                52

29.0 MISCELLANEOUS                                                            53
29.1 Authorization                                                            53
29.2 Independent Contractor                                                   53
29.3 Force Majeure                                                            53
29.4 Confidentiality                                                          54
29.5 Choice of Law                                                            55
29.6 Taxes                                                                    55
29.7 Assignment                                                               57
29.8 Billing and Payment; Disputed Amounts                                    57
<PAGE>
 
29.9      Dispute Resolution                                               58
29.10     Notices                                                          59
29.11     Section 252(i) Obligations                                       59
29.12     Joint Work Product                                               60
29.13     No Third Party Beneficiaries; Disclaimer of Agency               61
29.14     No License                                                       61
29.15     Technology Upgrades                                              61
29.16     Survival                                                         62
29.17     Entire Agreement                                                 62
29.18     Counterparts                                                     62
29.19     Modification, Amendment, Supplement or Waiver                    62
29.20     Successors and Assigns                                           62
29.21     Publicity                                                        62

                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------

Schedules
- ---------

Schedule 1.0        Certain Terms As Defined in the Act, As of July 16, 1996
Schedule 3.0        Implementation Schedule
Schedule 4.0        Interconnection Points in LATA
Schedule 4.2        Physical Architecture Diagram
Schedule 4.3        Initial Architecture Diagram
Schedule 4.5        Interconnection Points for Different Types of Traffic
Schedule 6.3        Rate Elements Under Meet Point Billing
Schedule 12.3       Support Services for Resale
Schedule 27.0       Performance Interval Dates for Specified Activities
Schedule 27.1       MFS Service Quality Standards

Exhibits
- --------

Exhibit A           Detailed Schedule of Itemized Charges
Exhibit B           Network Element Bona Fide Request
Exhibit C           Directory Assistance and Call Completion Services Agreement

                                      iv

<PAGE>
 
         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement under Sections 251 and 252 of the 
Telecommunications Act of 1996, is effective as of the 16th day of July, 1996 
(the "Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a 
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia 
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with 
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched 
Exchange Access Services, and other Telecommunications Services (all as defined 
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the 
respective obligations of the Parties and the terms and conditions under which 
the Parties will interconnect their networks and provide other services as 
required by the Act (as defined below) and additional services as set forth 
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996 
have specific requirements for interconnection, unbundling, and service resale, 
commonly referred to as the "Checklist", and the Parties intend that this 
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein 
and other good and valuable consideration, the receipt and sufficiency of which 
are hereby acknowledge, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA
and MFS (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements,
ancillary services, and wholesale Telecommunications Services available for
resale within each LATA in which they both operate within Virginia. As such,
this Agreement is an integrated package that reflects a balancing of interests
critical to the Parties. It will be submitted to the Virginia State Corporation
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of
the Agreement. So long as the Agreement remains in effect, neither Party shall
advocate before any legislative, regulatory, or other public forum that any term
of this Agreement be modified or eliminated, unless otherwise mutually agreed by
the Parties.

                                       1
<PAGE>
 
1.0  DEFINITIONS

     As used in this Agreement, the following terms shall have the meanings 
specified below in this Section 1.0. For convenience of reference only, the 
definitions of certain terms that are As Defined in the Act (as defined below) 
are set forth on Schedule 1.0.

     1.1   "Act" means the Communications Act of 1934 (47 U.S.C. 151 et. seq.), 
                                                                     --- ----
as amended by the Telecommunications Act of 1996, and as from time to time 
interpreted in the duly authorized rules and regulations of the FCC or the 
Commission.

     1.2   "ADSL" or "Asymmetrical Digital Subscriber Line" means a transmission
technology which transmits an asymmetrical digital signal of up to 0 mbps to the
Customer and up to 640 kbps from the Customer.

     1.3   [Reserved]

     1.4   "Agreement" means this Interconnection Agreement under Sections 251 
and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5   "Ancillary Traffic," means all traffic that is destined for ancillary
services, or that may have special billing requirements, including but not 
limited to the following: LSV/VCI, Directory Assistance, 911/E911. Operator 
Services (call completion), 800/888 database query, LIDB, and information 
services requiring special billing.

     1.6   "As Described in the Act" means as specifically defined by the Act 
and as from time to time interpreted in the duly authorized rules and 
regulations of the FCC or the Commission.

     1.7   "As Described in the Act" means as described in or required by the 
Act and as from time to time interpreted in the duly authorized rules and 
regulations of the FCC or the Commission.

     1.8   "Automatic Number Identification" or "ANI" means a Feature Group D 
signaling parameter which refers to the number transmitted through a network 
identifying the billing number of the calling party.

     1.9   "Calling Party Number" or "CPN" is a Common Channel Signaling ("CCS")
parameter which refers to the number transmitted through a network identifying 
the calling party.

     1.10  "Central Office Switch" means a switch used to provide 
Telecommunications Services, including, but not limited to:

           (a)  "End Office Switch" or "End Office" which is used to terminate 
Customer station Loops for the purpose of interconnection to each other and 
to trunks and

                                       2

<PAGE>
 
           (b)  "Tandem Switch" or "Tandem Office" which is a switching entity 
that is used to connect and switch trunk circuits between and among End Office 
Switches and between and among End Office Switches and carriers' aggregation
points, points of termination, or points of presence. An "Access Tandem Office"
or "Access Tandem" is a Tandem Office with billing and recording capabilities
that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End 
Office/Tandem Office Switch.

     1.11  [Reserved]

     1.12  "CLASS Features" means certain CCS-based features available to 
Customers including, but not limited to: Automatic Call Back: Call Trace: Caller
Identification, and future offerings.

     1.13  "Collocation" means an arrangement whereby one Party's (the
"Collocating Party") facilities are terminated in equipment necessary for
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a
second Party (the "Housing Party"). For purposes of Collocation, the "premises"
of a Housing Party is limited to a Housing Party Wire Center, other mutually
agreed-upon locations of the Housing Party, or any other location for which
Collocation has been ordered by the FCC or Commission. Collocation may be
"physical" or "virtual". In "Physical Collocation," the Collocating Party
installs and maintains its own equipment in the Housing Party's premises. In
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA
currently provides Collocation under terms, rates, and conditions as described
in tariffs on file or soon to be filed with the FCC and the Commission. Upon
request by either Party. BA and MFS will address the provision of additional
types of Collocation arrangements, including additional physical locations and
alternative utilizations of space and facilities.

     1.14  "Commission" means the Virginia State Corporation Commission.

     1.15  "Common Channel Signaling" or "CCS" means a method of transmitting 
call set-up and network control data over a digital signaling network separate 
from the public switched telephone network facilities that carry the actual 
voice or data traffic of the call. "SS7" means the common channel out of band 
signaling protocol developed by the Consultative Committee for International 
Telephone and Telegraph ("CCITT") and the American National Standards Institute 
("ANSI"). BA and MFS currently utilize this out-of-band signaling protocol. 
"CCSAC" or "CCSAS" means the common channel signaling access connection or 
service, respectively, which connects one Party's signaling point of 
interconnection ("SPOI") to the other Party's STP for the exchange of SS7 
messages.

<PAGE>
 
     1.16  "Competing Local Exchange Carrier" or "CLEC" means any Local Exchange
Carrier other than BA, operating as such in BA's certificated territory in 
Virginia. MFS is or will shortly become a CLEC.

     1.17  "Cross Connection" means a jumper cable or similar connection 
provided pursuant to Collocation at the digital signal cross connect, Main 
Distribution Frame or other suitable frame or panel between (i) the Collocating 
Party's equipment and (ii) the equipment or facilities of the Housing Party.

     1.18  "Customer" means a third-party residence or business subscriber to 
Telecommunications Services provided by either of the Parties.

     1.19  "Dialing Parity" is As Defined in the Act.

     1.20  "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.21  "Digital Signal Level 0" or "DS0" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.

     1.22  "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level 
signal in the time-division multiplex hierarchy. In the time-division 
multiplexing hierachy of the telephone network, DS1 is the initial level of 
multiplexing.

     1.23  "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level 
in the time-division multiplex hierarchy. In the time-division multiplexing 
hierarchy of the telephone network, DS3 is defined as the third level of 
multiplexing.

     1.24  "Exchange Access" is As Defined in the Act.

     1.25  "Exchange Message Record" or "EMR" means the standard used for
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is
contained in BR-010-200-010 CRIS Exchange Message Record, a Bell Communications
Research, Inc. ("Bellcore") document that defines industry standards for
Exchange Message Records.

     1.26  [Reserved]

     1.27  "FCC" means the Federal Communications Commission.

     1.28  "HDSL" or "High-Bit Rate Digital Subscriber Line" means a 
transmission technology which transmits up to 784 kbps simultaneously in both 
directions on a two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line 
code.

                                       4
 







 



<PAGE>
 
     1.29   "Independent Telephone Company" or "ITC" means any entity other than
BA which, with respect to its operations within Virginia, is an "Incumbent Local
Exchange Carrier" As Described in the Act.

     1.30   "Information Service Traffic" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which is
addressed to an information service provided over a Party's information services
platform.

     1.31   "Integrated Digital Loop Carrier" means a subscriber loop carrier
system which integrates within the switch at a DSI level that is twenty-four
(24) loop transmission paths combined into a 1.544 Mbps digital signal.

     1.32   "Integrated Services Digital Network" or "ISDN" means a switched
network service providing end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN") provides
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B-D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for
digital transmission of twenty-three (23) 64 kbps bearer channels and one 16
kbps data and signaling channel (23 B+D).

     1.33   "Interconnection" is as Described in the Act, and means the
connection of separate pieces of equipment or transmission facilities within,
between, or among networks. The architecture of Interconnection may include, but
is not limited to, Collocation Arrangements, entrance facilities, and Mid-Span
Meet arrangements.

     1.34   "Interexchange Carrier" or "IXC" means a carrier that provides,
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35   "Interim Number Portability" or "INP" means the use of existing and
available call routing, forwarding, and addressing capabilities (e.g. remote
                                                                 - -
call forwarding) to enable a Customer to receive Telephone Exchange Service 
provided by any Local Exchange Carrier operating within the exchange area with
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of
whether the Customer's chosen Local Exchange Carrier is the carrier that
originally assigned the number to the Customer.

     1.36   "InterLATA" is As Defined in the Act.

     1.37   "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.38   "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.

                                       5
<PAGE>
 
     1.39  "Line Status Verification" or "LSV" means an operator request for a 
status check on the line of a called party. The request is made by one Party's 
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40  "Local Access and Transport Area" or "LATA" is As Defined in the Act.

     1.41  "Local Exchange Carrier" or "LEC is As Defined in the Act. The 
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42  "Local Serving Wire Center" means a Wire Center that (i) serves the 
area in which the other Party's or a third party's Wire Center, aggregation 
point, point of termination, or point of presence is located, or any Wire Center
in the LATA in which the other Party's Wire Center, aggregation point, point of
termination or point of presence is located in which the other Party has
established a Collocation Arrangement or is purchasing an entrance facility, and
(ii) has the necessary multiplexing capabilities for providing transport
services.

     1.43  "Local Telephone Number Portability" or "LTNP" means "number
portability" As Defined in the Act.

     1.44  "Local Traffic," means traffic that is originated by a Customer of
one Party on that Party's network and terminates to a Customer of the other
Party on that other Party's network, within a given local calling area, or
expanded area service ("EAS") area, as defined in BA's effective Customer
tariffs. Local Traffic does not include traffic originated or terminated by a
commercial mobile radio service carrier.

     1.45  "Main Distribution Frame" or "MDF" means the primary point at which
outside plant facilities terminate within a Wire Center, for interconnection to
other telecommunications facilities within the Wire Center.

     1.46  "MECAB" means the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
("OBF"), which functions under the auspices of the Carrier Liaison Committee
("CLC") of the Alliance for Telecommunications Industry Solutions ("ATIS"). The
MECAB document, published by Bellcore as Special Report SR-BDS-000983, contains
the recommended guidelines for the billing of an Exchange Access service
provided by two or more LECs, or by one LEC in two or more states, within a
single LATA.

     1.47  "MECOD" means the Multiple Exchange Carriers Ordering and Design
(MECOD) Guidelines for Access Services - Industry Support Interface, a document
developed by the Ordering/Provisioning Committee under the auspices of OBF. The
MECOD document, published by Bellcore as Special Report SR-STS-002643,
establishes methods for processing orders for Exchange Access service which is
to be provided by two or more LLCs.

     1.48  "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched
Exchange Access Service to one

                                       6
   
<PAGE>
 
of the LEC's End Office Switches, with each LEC receiving an appropriate share 
of the transport element revenues as defined by their effective Exchange Access 
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an 
effective Meet-Point Billing arrangement.

     1.49 "Mid-Span Meet" means an Interconnection architecture whereby two
carriers fiber transmission facilities meet at a mutually agreed-upon 
Interconnection point.

     1.50 "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff" means
the MPB method whereby each LEC prepares and renders its own meet point bill in
accordance with its own Tariff(s) for the portion of the jointly-provided
Switched Exchange Access Service which the LEC provides.

     1.51  "Network Element" is As Defined in the Act.

     1.52 "Network Element Bona Fide Request" means the process described on
Exhibit B that prescribes the terms and conditions relating to a Party's request
that the other Party provide a Network Element not otherwise provided by the
terms of this Agreement.

     1.53  "North American Numbering Plan" or "NANP" means the numbering plan 
used in the United States that also serves Canada, Bermuda, Puerto Rico and 
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 
3-digit NXX code and 4-digit line number.

     1.54  "Numbering Plan Area" or "NPA" is also sometimes referred to as an 
area code. There are two general categories if NPAs, "Geographic NPAs" and 
"Non-Geographic NPAs". A Geographic NPA is associated with a defined geographic 
area, and all telephone numbers bearing such NPA are associated with services 
provided within that geographic area. A Non-Geographic NPA, also known as a 
"Service Access Code" or "SAC Code", is typically associated with a specialized 
telecommunications service which may be provided across multiple geographic NPA 
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55  "NXX," "NXX Code," or "End Office Code" means the three digit switch 
entity indicator (i.e. the first three digits of a seven digit telephone 
                  - - 
number).


     1.56  "Permanent Number Portability" or "PNP" means the use of a database
or other technical solution that comports with regulations issued by the FCC to
provide LTNP for all customers and service providers.

     1.57  "Port Element" or "Port" means a line card (or equivalent) and
associated peripheral equipment on an End Office Switch which serves as the
Interconnection between individual loops or individual Customer trunks and the
switching components of an End Office Switch and the associated switching
functionality in that End Office Switch. Each Port is typically associated with
one (or more) telephone number(s) which serves as the Customer's network
address.
<PAGE>
 
     1.58 "Rate Center Area" or "Exchange Area" means the specific geographic
point and corresponding geographic area which has been identified by a given LEC
as being associated with a particular NPA-NXX code assigned to the LEC for its
provision of Telephone Exchange Services. The Rate Center Area is the exclusive
geographic area which the LEC has identified as the area within which it will
provide Telephone Exchange Services bearing the particular NPA-NXX designation
associated with the specific Rate Center Area. A "Rate Center Point" is a
specific geographic point, defined by a V&H coordinate, located within the Rate
Center Area and used to measure distance for the purpose of billing Customers
for distance-sensitive Telephone Exchange Services and Toll Traffic.

     1.59 "Rate Demarcation Point" means the point of minimum penetration at the
Customer's premises or other point, a defined in a Party's Tariffs, where
network access recurring charges and LEC responsibility ends and beyond which
Customer responsibility begins.

     1.60 "Rating Point" or "Routing Point" means a specific geographic point
identified by a specific V&H coordinate. The Rating Point is used to route
inbound traffic to specified NPA-NXXs and to calculate mileage measurements for
distance-sensitive transport charges of switched access services. Pursuant to
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office
location, or a "LEC Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point corresponding to each unique and separate Rate Center.

     1.61 "Reciprocal Compensation" is As Described in the Act, and refers to 
the payment arrangements that recover costs incurred for the transport and 
termination of Local Traffic originating on one Party's network and terminating 
on the other Party's network.

     1.62 "Service Control Point" or "SCP" means the node in the common channel 
signaling network to which informational requests for service handling, such as 
routing, are directed and processed. The SCP is a real time database system 
that, based on a query from a service switching point and via a Signaling 
Transfer Point, performs subscriber or application-specific service logic, and 
then sends instructions back to the SSP on how to continue call processing.

     1.63 "Signaling Transfer Point" or "STP" means a specialized switch that 
provides SS7 network access and performs SS7 message routing and screening.

     1.64 "Switched Access Detail Usage Data" means a category 1101XX record as 
defined in the EMR Bellcore Practice BR-010-200-010.

     1.65 "Switched Access Summary Usage Data" means a category 1150XX record as
defined in the EMR Bellcore Practice BR-010-200-010.

                                       8

<PAGE>
 
     1.66  "Switched Exchange Access Service" means the offering of
transmission and switching services for the purpose of the origination or
termination of Toll Traffic. Switched Exchange Access Services include but may
not be limited to: Feature Group A, Feature Group B, Feature Group D, 700
access, 800 access, 888 access, and 900 access.

     1.67  "Synchronous Optical Network" or "SONET" means an optical 
interface standard that allows inter-networking of transmission products from 
multiple vendors. The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are 
direct multiples of the base rate, up to 13.22 Gpbs.

     1.68  "Tariff" means any applicable federal or state tariff of a Party,
or standard agreement or other document that sets forth the generally available 
terms and conditions under which a Party offers a particular service, facility, 
or arrangement.

     1.69  "Technically Feasible Point" is As Described in the Act.

     1.70  "Telecommunications" is As Defined in the Act.

     1.71  "Telecommunications Act" means the Telecommunications Act of 1996
and any rules and regulations promulgated thereunder.

     1.72  "Telecommunications Carrier" is As Defined in the Act.

     1.73  "Telecommunications Service" is As Defined in the Act.

     1.74  "Telephone Exchange Service," sometimes also referred to as 
"Exchange Service," is As Defined in the Act. Telephone Exchange Service 
generally provides the Customer with a telephonic connection to, and a unique 
telephone number address on, the public switched telecommunications network, and
enables such Customer to place or receive calls to all other stations on the 
public switched telecommunications network.

     1.75  "Toll Traffic" means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that Party's network and is not Local Traffic or Ancillary Traffic. Toll Traffic
may be either "IntraLATA Toll Traffic" or "InterLATA Toll Traffic," depending on
whether the originating and terminating points are within the same LATA.

     1.76  "Transit Traffic" means any traffic that originates from or
terminates at MFS's network, "transits" BA's network substantially unchanged,
and terminates to or originates from a third carrier's network, as the case may
be. "Transit Traffic Service" provides MFS with the ability to use its
connection to a BA Access Tandem Switch for the delivery of calls which
originate or terminate with MFS and terminate to or originate from a carrier
other than BA, such as another CLEC, A LEC other than BA, or a wireless carrier.
In these cases, neither the originating nor terminating Customer is a Customer
of BA. This service is provided through BA's Access Tandem

                                       9
<PAGE>
 
Switches. "Transit Traffic" and "Transit Traffic Service" do not include or
apply to traffic that is subject to an effective Meet-Point Billing arrangement.


     1.77   "Trunk Side" means a Central Office Switch connection that is 
capable of, and has been programmed to treat the circuit as, connecting to 
another switching entity (e.g. another carrier's network). Trunk Side 
connections offer those transmission and signaling features appropriate for the 
connection of switching entities.

     1.78   "Unbundled Local Loop Element" or "ULL" means a transmission path 
that extends from a Main Distribution Frame, DSX-panel, or functionally 
comparable piece of equipment in the Customer's serving End Office to the Rate 
Demarcation Point (or network interface device (NID) if installed) in or at a 
Customer's premises. The actual loop transmission facilities used to provide an 
ULL may utilize any of several technologies.

     1.79   "Verification with Call Interruption" or "VCI" means a service that 
may be requested and provided when Line Status Verification has determined that 
a line is busy due to an ongoing call. VCI is an operator interruption of that 
ongoing call to inform the called party that a calling party is seeking to 
complete his or her call to the called party.

     1.80   "Voice Grade" means either an analog signal of 300 to 3000 Hz or a 
digital signal of 56/64 kilobits per second. When referring to digital voice 
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.81   "Wire Center" means a building or portion thereof in which a Party 
has the exclusive right of occupancy and which serves as a Routing Point for 
Switched Exchange Access Service.


2.0  INTERPRETATION AND CONSTRUCTION.

     2.1   All references to Sections, Exhibits and Schedules shall be 
deemed to be references to Sections of, and Exhibits and Schedules to, this
Agreement unless the context shall otherwise require. The headings used in this
Agreement are inserted for convenience of reference only and are not intended to
be a part of or to affect the meaning of this Agreement. Unless the context
shall otherwise require, any reference to any agreement, other instrument
(including BA or other third party offerings, guides or practices), statute,
regulation, rule or tariff is to such agreement, instrument, statute,
regulation, or rule or tariff as amended and supplemented from time to time
(and, in the case of a statute, regulation, rule or tariff, to any successor
provision).

     2.2   Subject to the terms set forth in Section 20, each Party hereby 
incorporates by reference those provisions of its tariffs that govern the 
provision of any of the services or facilities provided hereunder. If any 
provision of this Agreement and an applicable tariff cannot be reasonably 
construed or interpreted to avoid conflict, the Parties agree to negotiate in 
good faith to reconcile and resolve such conflict. If any provision contained in
this main body of the Agreement and any Exhibit hereto cannot be reasonably 
construed or interpreted to avoid conflict, the 

                                      10
<PAGE>
 
provision contained in this main body of the Agreement shall prevail. The fact
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for
finding, a conflict for purposes of this Section 2.

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1   Subject to the terms and conditions of this Agreement, each Party 
shall exercise its best efforts to adhere to the Interconnection Activation 
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to 
provide fully operational service predominantly over its own Telephone Exchange 
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes 
of this Agreement, MFS's service in Virginia shall be considered provided 
"predominantly over its own Telephone Exchange Service facilities" if MFS uses 
its own Central Office Switch(es) (as opposed to resale of another carrier's 
Telephone Exchange Service or Ports) to serve the majority of its Telephone 
Exchange Service Customers, its own interoffice transport facilities for the 
majority of its interoffice transport needs, and its own local loops (or 
functional equivalent), in addition to resale of other carriers' Telephone 
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2   Schedule 3.0 may be revised and supplemented from time to time upon 
the mutual agreement of the Parties to reflect the intention of the Parties to 
interconnect in additional LATAs pursuant to subsection 4.4 by attaching one or 
more supplementary schedules to Schedule 3.0. The Parties stipulate and agree 
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act. MFS represents that it 
is, or intends to become, a provider of Telephone Exchange Service to 
residential and business subscribers offered exclusively over its own Telephone 
Exchange Service facilities or predominantly over its own Telephone Exchange 
Service facilities in combination with the resale of the Telecommunications 
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local 
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit 
Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to the terms
and conditions of this Agreement, Interconnection of the Parties facilities and 
equipment for the transmission and routing of Local Traffic and Toll Traffic 
pursuant to this Section 4 shall be established on or before the corresponding 
"Interconnection Activation Date" shown for each such LATA within Virginia on 
Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and supplemented
from time to time upon the mutual agreement of the Parties to reflect 
Interconnection in additional LATAs in Virginia pursuant to subsection 4.4 by 
attaching one or more supplementary addenda to such Schedules.

                                      11
<PAGE>
 
     4.1  SCOPE

          4.1.1   Section 4 describes the architecture for Interconnection of 
the Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct trunk groups:

          Traffic Exchange Trunks for the transmission and routing of
          -----------------------
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251 (c)(2) of the Act, in accordance with Section 5 below;

          Access Toll Connecting Trunks for the transmission and routing of
          -----------------------------
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Service via a BA
          Access Tandem, pursuant to Section 251 (c)(2) of the Act, in
          accordance with Section 6 below;

          Information Services Trunks for the transmission and routing of
          ---------------------------
          terminating Information Services Traffic in accordance with Section 7
          below;

          LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
          --------------
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating 
          ---------------
          E911/911 traffic, in accordance with Section 7 below;

          Directory Assistance Trunks for the transmission and routing of
          ---------------------------
          terminating directory assistance traffic, in accordance with 
          subsection 19.4 below; and

          Operator services (call completion) Trunks for the transmission and
          ------------------------------------------
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2   The SONET interconnection arrangement described in subsection 
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA
Toll Traffic until such time as the Parties have agreed to appropriate
compensation arrangements relating to the exchange of other types of traffic
over such system, and (ii) subject to the Parties' reaching agreement on an
appropriate compensation arrangement in the event either Party will be providing
or utilizing (in terms of minutes of use) significantly more than one-half of
the SONET facility. Unless otherwise agreed to by the Parties, the SONET system
described herein shall not be used to exchange InterLATA Toll TRaffic. Until the
SONET system has been established by the Parties in accordance with subsection
4.3 and this subsection 4.1.2 the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
IntraLATA and InterLATA) Traffic.

                                      12
<PAGE>
 
          4.1.3   To the extent required by Section 251 of the Act, the Parties 
represent that the arrangements provided in subsections 4.2 and 4.3 of this 
Agreement provide for Interconnection to each other's networks at any 
technically feasible point.  For the purposes of this Agreement, the Parties 
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a 
Local Servicing Wire Center and/or other points as specified herein, and, in the
case of MFS, at a node or Central Office and/or other points as specified herein
(collectively, the "Interconnection Points" or "IPs").

          4.1.4   The Parties shall establish physical interconnection points at
the available IPs at the locations designated in Schedule 4.0.  The mutually 
agreed-upon IPs and the MFS network at which MFS will provide transport and 
termination of traffic shall be designated as the MFS Interconnection Points 
("M-IPs"); the mutually agreed-upon IPs and BA network shall be designated as 
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of 
charging for the transport of traffic from the BA-IP to the M-IP in any given 
LATA, the M-IP shall be no further than an entrance facility away from the BA-IP
in such LATA.  The Parties may by mutual agreement establish additional 
interconnection points at any technically feasible points consistent with the 
Act.

     4.2  PHYSICAL ARCHITECTURE.  In each LATA identified on Schedule 4.0 MFS 
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous 
Optical Network ("SONET") transmission system by which they shall interconnect 
their networks pursuant to the joint network reconfiguration and grooming plan 
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the 
following specifications:

          4.2.1   The SONET system shall be used to deliver appropriate traffic 
to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2   The SONET transmission system in each LATA shall be configured
substantially as illustrated in Schedule 4.2 and pursuant to the Joint Grooming 
Plan, or as otherwise mutually agreed.  The Parties shall agree upon which Party
or Parties shall be responsible for procuring, installing, and maintaining the 
agreed-upon Optical Line Terminating Multiplexor ("OLTM") equipment, fiber optic
facilities and other equipment pursuant to the Joint Grooming Plan, as 
illustrated in that Schedule.

          4.2.3   The physical interface of MFS's and BA's facilities necessary 
to effect SONET transmission shall be at the optical level via a Mid-Span Meet 
or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1   The Parties agree to provide initial interconnection 
arrangements utilizing electric handoffs, substantially as illustrated in 
Schedule 4.3, for a period of no more than eighteen (18) months after the later 
of the Effective Date and the LATA Start Date set forth for the LATA in Schedule
3.0; provided, however, that such initial interconnection arrangements

                                      13
<PAGE>
 
shall continue until (i) facilities suitable for the SONET arrangements 
described in subsection 4.2 are established by each of the Parties in its own 
sole discretion in the LATA at the mutually agreed-upon SONET meet points and 
made available, and (ii) the Parties have agreed upon fully compatible OLTM 
equipment for use with such facilities.

          4.3.2   The Parties agree to utilize the M-IP and BA-IP in each LATA 
as designated in Schedule 4.0 as the points from which each Party will provide 
the transport and termination of traffic.

          4.3.3   MFS shall provide its own facilities for the delivery of 
traffic to a collocation arrangement established at the BA-IP pursuant to 
Section 13.  Bell Atlantic shall provide transport and termination of the 
traffic beyond the BA-IP.

          4.3.4   BA shall purchase an MFS entrance facility (and any necessary 
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the 
M-IP.  Alternatively, BA may choose to provide its own facilities to a 
collocation arrangement established at the M-IP pursuant to Section 13. MFS 
shall provide transport and termination of the traffic beyond the M-IP.

          4.3.5   Under this initial architecture described in this subsection
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5
below and pursuant to the other Party's Switched Exchange Access Service
tariffs. The other Party's Switched Exchange Access Service rates shall apply to
such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.

     4.4  INTERCONNECTION IN ADDITIONAL LATAs

          4.4.1   If MFS determines to offer Telephone Exchange Services in any 
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange 
Services, MFS shall provide written notice to BA of the need to establish   
Interconnection in such LATA pursuant to this Agreement.

          4.4.2   The notice provided in subsection 4.4.1 shall include (i) the
initial Routing Point MFS has designated in the new LATA: (ii) MFS's requested 
Interconnection Activation Date (and related milestone dates in accordance with 
the format in Schedule 3.0): and (iii) a non-binding forecast of MFS's trunking 
requirements.

          4.4.3   Unless otherwise agreed to by the Parties, the Parties shall 
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local 
Serving Wire Center that houses an Access Tandem Office within the LATA nearest 
to the M-IP (as measured in airline miles utilizing the V&H coordinates method) 
as the BA-IP in that LATA, provided that, for the 

                                      14



<PAGE>
 
purpose of charging for the transport of traffic from the BA-IP to the M-IP, the
M-IP, shall be no further than an entrance facility away from the BA-IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to
reflect the schedule applicable to each new LATA requested by MFS, provided,
however, that unless agreed by the Parties, the Interconnection Activation Date
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten
(10) business days of BA's receipt of MFS's notice. BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party
shall make available Interconnection Points and facilities for routing of
traffic from those Interconnection Points as designated in Schedule 4.5. Any
additional traffic that is not covered in Schedule 4.5 shall be subject to
separate negotiations between the Parties, except that (i) either Party may
deliver traffic of any type or character to the other Party for termination as
long as the delivering Party pays the receiving Party's then current Switched
Exchange Access rates for such traffic, and (ii) upon a bona fide request from
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an
agreement covering the exchange of such traffic.


5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO 
SECTION 251(C)(2)

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups 
(the "Traffic Exchange Trunks") to be effected over the Interconnections 
specified in Section 4.0 for the transmission and routing of Local Traffic and 
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange 
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-1 level or higher
for exchange of Local and Toll Traffic. Higher speed connections shall be made,
when and where available, in accordance with the Joint Grooming Plan prescribed
in Section 10. Ancillary Traffic trunk groups may be made below a DS-1 level, as
may be agreed to by the Parties.

          5.2.2. Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

          5.3.1  For purposes of routing MFS traffic to BA, the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own or other carriers' traffic. For purposes of routing
BA traffic to MFS, the subtending arrangements

                                      15
<PAGE>
 
between MFS Access Tandem Switches (or functional equivalent and MFS End Office 
Switches (or functional equivalent) shall be the same as the Access Tandem/End 
Office subtending arrangements (or functional equivalent) which MFS maintains 
for the routing of its own or other carriers' traffic.

     5.4  SIGNALING

     Each Party will provide the other Party with access to its databases and 
associated signaling necessary for the routing and completion of the other 
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5  GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance 
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6  MEASUREMENT AND BILLING

        5.6.1  For billing purposes, each Party shall pass Calling Party Number 
("CPN") information on each call carried over the Traffic Exchange Trunks, 
wherever technically feasible. At such time as either Party has the ability, as 
the Party receiving the traffic, to use such CPN information to classify on an 
automated basis traffic delivered by the other Party as either Local Traffic or 
Toll Traffic, such receiving Party shall bill the originating Party the Local 
Traffic termination rates, Intrastate Exchange Access rates, or Interstate 
Exchange Access rates applicable to each minute of Traffic for which CPN is 
passed, as provided in Exhibit A and applicable Tariffs.

        5.6.2  If, under the circumstances set forth in subsection 5.6.1, it is
not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party the
Local Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, for which CPN is passed. For the remaining up
to ten percent (10%) of calls without CPN information, the receiving Party shall
bill the originating Party for such traffic as Local Traffic termination rates,
Intrastate Exchange Access rates, or Interstate Exchange Access rates applicable
to each minute of traffic, as provided in Exhibit A and applicable Tariffs, in
direct proportion to the minutes of use of calls passed with CPN information.

        5.6.3  If it is not technically feasible for the originating Party to 
pass CPN on more than ten percent (10%) of calls, or if the receiving Party 
lacks the ability to use CPN information to classify on an automated basis 
traffic delivered by the other Party as either Local Traffic or Toll Traffic, 
and the originating Party chooses to combine Local and Toll Traffic on the same 
trunk group, it will supply an auditable Percent Local Use ("PLU") report 
quarterly, based on the previous three months' traffic, and applicable to the 
following three months. If the originating Party also chooses to combine 
Interstate and Intrastate Toll Traffic on the same trunk

                                      16
<PAGE>
 
group, it will supply an auditable Percent Interstate Use ("PLI") report 
quarterly, based on the previous three months' terminating traffic, and 
applicable to the following three months. In lieu of the foregoing PLU and/or 
PIU reports, the Parties may agree to provide and accept reasonable surrogate 
measures for an agreed-upon interim period.

        5.6.4. Measurement of billing minutes for purposes of determining 
terminating compensation shall be in conversation seconds.

     5.7  RECIPROCAL COMPENSATION ARRANGEMENTS - SECTION 251(B)(5)

      Reciprocal Compensation arrangements address the transport and termination
of Local Traffic. BA's delivery of Traffic to MFS that originated with a third
carrier is addressed in subsection 7.3. Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and terminations of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

        5.7.1  Nothing in this Agreement shall be construed to limit either 
Party's ability to designated the areas within which that Party's Customers may 
make calls which that Party rates as "local" in its Customer Tariffs.

        5.7.2  The Parties shall compensate each other for transport and 
termination of Local Traffic in an equal and symmetrical manner at the rates 
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if 
not set forth therein, in the applicable Tariff(s) of the terminating Party, as 
the case may be. These rates are to be applied at he M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges, 
including port or transport charges, shall apply for the termination of Local 
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A. 
When Local Traffic is terminated over the same trunks as Toll Traffic, any port 
or transport or the other applicable access charges related to the Toll Traffic 
shall be prorated to be applied only to the Toll Traffic.

        5.7.3  The Reciprocal Compensation arrangements set forth in this 
Agreement are not applicable to Switched Exchange Access Service. All Switched 
Exchange Access Service and Toll Traffic shall continue to be goverened by the 
terms and conditions of the applicable federal and state Tariffs.

        5.7.4  Compensation for transport and termination of all Traffic which 
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5.

        5.7.5  The designation of Traffic as Local or Toll for purposes of 
compensation shall be based on the actual originating and terminating points of 
the complete end-to-end call, regardless of the carrier(s) involved in carrying 
any segment of the call.

                                      17
<PAGE>
 
          5.7.6  Each Party reserves the right to measure and audit all Traffic 
to ensure that proper rates are being applied appropriately. Each Party agrees 
to provide the necessary Traffic data or permit the other Party's recording 
equipment to be installed for sampling purposes in conjunction with any such 
audit.

          5.7.7  The Parties will engage in settlements of alternate-billed 
calls (e.g. collect, calling card, and third-party billed calls) originated or 
authorized by their respective Customers in Virginia in accordance with the 
terms of an appropriate billing services agreement for intraLATA intrastate 
alternate-billed calls or such other arrangement as may be agreed to by the 
Parties.

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2).

     6.1  SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over 
the Interconnections specified in Section 4 for the transmission and routing of 
traffic between MFS Telephone Exchange Service Customers and Interexchange 
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

       6.2.1  MFS shall establish Access Toll Connecting Trunks by which it will
provide tandem-transported Switched Exchange Access Services to Interexchange
Carriers to enable such Interexchange Carriers to originate and terminate
traffic to and from MFS's Customers.

       6.2.2  Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access to allow MFS's Customers to connect
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

       6.2.3  The Access Toll Connecting Trunks shall be two-way trunks 
connecting an End Office Switch MFS utilizes to provide Telephone Exchange 
Service and Switched Exchange Access in a given LATA to an Access Tandem BA 
utilizes to provide Exchange Access in such LATA.

       6.2.4  The Parties shall jointly determine which BA Access Tandem(s) will
be subtended by each MFS End Office Switch. MFS's End Office switch shall 
subtend the BA Access Tandem that would have served the same rate center on BA's
network. Alternative configurations will be discussed as part of the Joint Plan.

     6.3  MEET-POINT BILLING ARRANGEMENTS

                                      18

<PAGE>
 
          6.3.1     MFS and BA will establish Meet-Point Billing arrangements in
order to provide a common transport option to Switched Access Services Customers
via an Access Tandem Switch in accordance with the Meet-Point Billing guidelines
contained in the OBF's MECAB and MECOD documents, except as modified herein, and
BA's Virginia Tariff Number 217. Section 2.4.8. The arrangements described in
this Section 6 are intended to be used to provide Switched Exchange Access
Service that originates and/or terminates on a Telephone Exchange Service that
is provided by either Party, where the transport component of the Switched
Exchange Access Service is routed through a Tandem Switch that is provided by
BA.

          6.3.2     In each LATA, the Parties shall establish MPB arrangements 
between the applicable Rating Point/BA Local Serving Wire Center combinations.

          6.3.3     Interconnection for the MPB arrangement shall occur at the 
BA-IP in the LATA, unless otherwise agreed to by the Parties.

          6.3.4     MFS and BA will use reasonable efforts, individually and
collectively, to maintain provisions in their respective state access tariffs,
and or provisions within the National Exchange Carrier Association ("NECA")
tariff No. 4. or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

          6.3.5     Each Party shall implement the "Multiple Bill Single Tariff"
or "Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an 
IXC for the portion of the jointly provided telecommunications service provided 
by that Party.

          6.3.6     The rate elements to be billed by each Party are as set
forth in Schedule 6.3. The actual rate values for each Party's affected access
service rate element shall be the rates contained in that Party's own effective
federal and state access tariffs, or other document that contains the terms
under which that Party's access services are offered. The MPB billing
percentages for each Rating Point/BA Local Serving Wire Center combination shall
be calculated in accordance with the formula set forth in subsection 6.3.16
below.

          6.3.7     Each Party shall provide the other Party with the billing 
name, billing address, and Carrier Identification Code ("CIC") of the IXC, and 
identification of the IXC's Local Serving Wire Center in order to comply with 
the MPB notification process as outlined in the MECAB document via facsimile or 
such other media as the Parties may agree to.

          6.3.8     BA shall provide MFS with the Switched Access Detail Usage 
Data (category 1101XX records) on magnetic tape or via such other media as the 
Parties may agree to, no later than ten (10) business days after the date the 
usage occurred.

          6.3.9     MFS shall provide BA with the Switched Access Summary Usage
Data (category 1150XX records) on magnetic tape or via such other media as the 
Parties may agree, no later than ten (10) business days after the date of its 
rendering of the bill to the relevant IXC, which bill shall be rendered no less 
frequently than monthly.

                                      19




<PAGE>
 
          6.3.10  Each Party shall coordinate and exchange the billing account
reference ("BAR") and billing account cross reference ("BACR") numbers or 
Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each Party 
shall notify the other if the level of billing or other BAR/BACR elements 
change, resulting in a new BAR BACR number, or if the OCN changes.

          6.3.11  Errors may be discovered by MFS, the IXC or BA. Each Party 
agrees to provide the other Party with notification of any errors it discovers 
within two (2) business days of the date of such discovery. In the event of a 
loss of data, both Parties shall cooperate to reconstruct the lost data and, if 
such reconstruction is not possible, shall accept a reasonable estimate of the 
lost data based upon prior usage data.

          6.3.12  Either Party may request a review or audit of the various 
components of access recording up to a maximum of two (2) audits per calendar 
year. All costas associated with each review and audit shall be borne by the 
requesting Party. Such review or audit shall be conducted subject to 
confidentiality protection and during regular business hours. A Party may 
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

          6.3.13  Nothing contained in this subsection 6.3. shall create any
liability for damages, losses, claims, costs, injuries, expenses or other
liabilities whatsoever on the part of either Party (other than as may be set
forth in MECAB or in any applicable Tariff).

          6.3.14  The Parties shall not charge one another for the services 
rendered or information provided pursuant to this subsection 6.3.

          6.3.15  MPB will apply for all traffic bearing the 500, 900, 800/888
(to the extent provided by an IXC) or any other non-geographic NPA which may be
likewise designated for such traffic in the future.

          6.3.16  In the event MFS determines to offer Telephone Exchange
Services in another LATA in which BA operates an Access Tandem Switch, BA shall
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for
the BA End Offices in the area where the MFS Rating Point(s) associated with the
NPA-NXX(s) to from which the Switched Exchange Access Services are homed. The
MPB billing percentages for each new Rating Point/BA Local Serving Wire Center
combination shall be calculated according to the following formula:

                        a / (a - b)= MFS Billing Percentage
                                      and
                        b / (a + b)= BA Billing Percentage

                    where:
                    ------
          
                    a = the airline mileage between the Rating Point and the 
          actual point of interconnection for the MPB arrangement; and

                                      20
<PAGE>
 
                    b = the airline mileage between the BA Local Serving Wire
               Center and the actual point of interconnection for the MPB
               arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange 
Services and its calculation of the billing percentages which should apply for 
such arrangement, as part of the notice required by subsection 4.4.1 above. 
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS 
shall confirm the new Rating Point/BA Local Serving Wire Center combination and 
billing percentages. Nothing in this subsection 6.3.16 shall be construed to 
limit MFS's ability to select to interconnect with BA in additional LATAs by 
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

     6.4       800/888 TRAFFIC

     The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.
          
               6.4.1.    When MFS delivers untranslated 800/888 calls to BA for 
completion 

                         (a)   to an IXC, BA shall:

                               (i)   Provide a MPB record in an industry
                               standard format to MFS; and

                               (ii)  Bill the IXC the appropriate BA query
                               charge associated with the call.

                         (b)   as an IntraLATA call to BA or another LEC in the 
LATA, BA shall


                               (i)   Provide a copy record in an industry
                               standard format to MFS:
   

                               (ii)  Bill MFS the appropriate BA query charge 
                               associated with the call: and 

                               (iii) Submit the call records to ITORP for
                               payment by BA or the LEC that is the 800/888
                               service provider of MFS's and any intermediate
                               LEC's Tariffed Exchange Access charges and query
                               charges.

               
               6.4.2     When BA delivers 800/888 calls originated by BA's or 
another LEC's Customers to MFS for completion
<PAGE>
 
                    (a)  to MFS in its capacity as an IXC, BA shall:

                         (i)   Bill MFS the appropriate BA query charge 
                         associated with the call: and

                         (ii)  Bill MFS the appropriate FGD Exchange Access
                         charges associated with the call.

                    (b)  as an IntraLATA call to MFS in its capacity as a LEC.

                         (i)   BA shall submit the appropriate call records to
                         ITORP for payment by MFS of BA's (and another LEC's, if
                         appropriate) Tariffed Exchange Access charges: and

                         (ii)  MFS shall pay the originating LEC's appropriate
                         query charge associated with the call.
               
     
7.0       TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

          7.1  INFORMATION SERVICES TRAFFIC

          The following provisions shall apply only to MFS-originated
Information Services Traffic directed to an information services platform
connected to BA's network. At such time as MFS connects Information Services
platforms to its network, the Parties shall agree upon a suitable arrangement
for BA-Originated Information Services Traffic.

               7.1.1  MFS shall route Information Services Traffic that
originates on its own network to the appropriate information services
platform(s) connected to BA's network. MFS will establish a dedicated trunk
group to the BA information services serving switch. This trunk group will be
utilized to allow MFS to route information service traffic originated on its
network to BA.

               7.1.2  MFS shall provide an electronic file transfer or monthly
magnetic tape containing recorded call detail information to BA.

               7.1.3  BA shall provide to MFS via electronic file transfer or 
magnetic tape or other means as available all necessary information to rate the 
Information Services Traffic to MFS's Customers pursuant to the BA's agreements 
with each information services provider. Information shall be provided in as 
timely a fashion as practical in order to facilitate record review and reflect 
actual prices set by the individual information services providers.

               7.1.4  MFS shall bill and collect such information services 
provider charges and remit the amounts collected to BA less:

                                      22




   


 





















           
<PAGE>
 
          (a)    The Information Services Billing and Collection fee set forth
     in Exhibit A; and

          (b)    An uncollectibles reserve calculated based on the
     uncollectibles reserve in BA's billing and collection agreement with the
     applicable information services provider; and

         (c)     Customer adjustments provided by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and
Customer adjustments to allow BA to pass through the adjustments to the
information services provider, and BA shall pass through such adjustments.
However, if the information services provider disputes such adjustments and
refuses to accept such adjustments, MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputed adjustments shall be solely
between MFS and the information services provider.

          7.1.5  Nothing in this Agreement shall restrict either Party from
offering to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

          7.1.6  The Parties may agree to separate arrangements for the billing
and compensation of variable rated (e.g. 970.540) information services.

          7.1.7  The Information Services Traffic addressed herein does not
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1  Each Party shall offer LSV and VCI services to enable its
Customers to verify and/or interrupt calls of the other Party's Customers. In
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party
(Party A) and the responding Party (Party B) shall perform in accordance with
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to
be agreed upon between the Parties.

          7.2.2  The Party B operator shall only verify the status of the line
(LSV) or interrupt the line to inform the called party that there is a call
waiting. The Party B operator will not complete the telephone call of the
Customer initiating the LSV VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable
charge apply whether or not the called party releases the line.

          7.2.3  Each Party's operator bureau shall accept LSV and VCI inquires
from the operator bureau of the other Party in order to allow transparent
provision of LSV/VCI Traffic between the Parties' networks.

                                      23

<PAGE>
 
          7.2.4 Each Party shall route LSV/VCI Traffic inquiries over separate
direct trunks (and not the Local/IntraLATA/InterLATA Trunks) established between
the Parties' respective operator bureaus. Each Party shall offer interconnection
for LSV/VCI traffic at its Local Serving Wire Center, operator services Tandem
Office subtended by such Local Serving Wire Center, or other mutually agreed
point in the LATA. Separate LSV/VCI trunks delivered at the Local Serving Wire
Center will be directed to the operator services Tandem Office designated by
Party B. Unless otherwise mutually agreed, the Parties shall configure LSV/VCI
trunks over the Interconnection architectures in accordance with the terms of
Section 4, consistent with the Joint Grooming Plan. Party A shall outpulse the
appropriate NPA, ATC Code, and Routing Code (operator code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a 
reciprocal local traffic exchange arrangement (either via written agreement or 
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it 
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as 
quickly as commercially reasonable following the Effective Date and to provide 
copies thereof to BA, but continues to utilize BA's Transit Service for the 
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC, 
MFS shall, in addition to paying the rate set forth in Exhibit A for said 
Transit Service, pay BA any charges or costs such terminating third party 
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred by 
                                       ----
BA in delivering or terminating such Traffic and/or resulting from MFS's failure
to secure said reciprocal local traffic exchange arrangement. BA will, upon 
request, provide MFS with all reasonable cooperation and assistance in obtaining
such arrangements. The Parties agree to work cooperatively in appropriate 
industry fora to promote the adoption of reasonable industry guidelines relating
to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in 
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will 
deliver each call to each involved network with CCS and the appropriate 
Transactional Capabilities Application Part ("TCAP") message to facilitate full 
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and
exchange records between the Parties and with the terminating carrier to 
facilitate the billing process to the originating network.

          7.3.4  Transit Traffic shall be routed over the Traffic Exchange 
Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

                                      24

<PAGE>
 
          7.4.1  MFS will interconnect to the BA 911/E911 selective routers or 
911 Tandem Offices, where available, which serve the areas in which MFS provides
Telephone Exchange Services, for the provision of 911/E911 services and for 
access to all subtending Public Safety Answering Points ("PSAP"). In such 
situations, BA will provide MFS with the appropriate CLLI codes and 
specifications of the Tandem Office serving area. In areas where E911 is not 
available. MFS and BA will negotiate arrangements to connect MFS to the 911 
service.

          7.4.2  Path and route diverse interconnections for 911/E911 shall be 
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed,
and as required by law or regulation.

          7.4.3  Upon request, BA will provide MFS with the following:

          (a)    an electronic interface, when available, through which MFS 
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911
     information such as name, address, and telephone number in writing for BA's
     entry into the 911 database system. Any 911-related data exchanged between
     the Parties shall conform to the National Emergency Number Association
     standards;

          (b)    a file containing the Master Street Address Guide ("MSAG"), as 
     may be updated from time to time, for the exchanges or communities
     specified;

          (c)    a return of any MFS E911 data entry files containing errors, so
     that MFS may ensure the accuracy of the Customer records; and

          (d)    PSAP 911 Tandem information.

          7.4.4  In cases where a Customer of one Party elects to discontinue 
its service and become the Customer of the other Party ("Party B") but desires
to retain its original telephone number pursuant to an INP or PNP arrangement,
Party B will outpulse the telephone number to which the call has been forwarded
(i.e. the Customer's ANI) to the 911 Tandem Office. Party B will also provide
 - -
the 911 database with both the forwarded number and the directory number, as
well as the appropriate address information of the Customer.

          7.4.5  BA and MFS will use their best efforts to facilitate the
prompt, robust, reliable and efficient interconnection of MFS systems to the
911/E911 platforms.

          7.4.6  BA and MFS will work cooperatively to arrange meetings with 
PSAPs to answer any technical questions the PSAPs, or county or municipal 
coordinators may have regarding the 911/E911 arrangements. BA shall assist MFS 
in identifying the appropriate person in each municipality for the purpose of 
obtaining the ten-digit subscriber number of each PSAP.

                                      25
<PAGE>
 
          7.4.7  The Parties acknowledge that the provision of INP, until PNP
with full 911 compatability is available, creates a special need to have the
Automatic Location Identification ("ALI") screen reflect two number: the "old"
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification
("TCI") of the company that provides service to the calling line as part of the
ALI display. Until such time as TCI is operational, however, BA and MFS agree to
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8  MFS will compensate BA for connections to its 911/E911 pursuant
to Exhibit A.

          7.4.9  MFS will comply with all applicable rules and regulations 
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY  Ancillary Traffic that may be terminated 
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be 
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise
adversely affect in any manner either Party's right to employ or to request and
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code
Assignment Guidelines, as may be amended from time to time, or to establish, by
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX
codes. Until such time as number administration is provided by a third party,
BA shall provide MFS access to telephone numbers by assigning NXX codes to MFS
in accordance with such Assignment Guidelines.

     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing 
Guide ("LERG") in order to recognize and route traffic to the other Party's 
assigned NXX codes at all times. Neither Party shall impose any fees or charges 
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this agreement, MFS shall 
adopt the Rate Center Areas and Rate Center Points that the Commission has 
approved for BA, in all areas where BA and MFS service areas overlap, and MFS 
shall assign whole NPA-NXX codes to each Rate Center unless the LEC industry 
adopts alternative methods of utilizing NXXs in the manner adopted by the NANP.

                                      26

<PAGE>
 
     8.4  MFS will also designate a Routing Point for each assigned NXX code. 
MFS shall designate one location for each Rate Center Area as the Routing Point 
for the NPA-NXXs associated with that Area, and such Routing Point shall be 
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in 
this Agreement is intended to, and nothing in this Agreement shall be construed 
to, in any way constrain MFS's choices regarding the size of the local calling 
area(s) that MFS may establish for its Customers, which local calling areas may 
be larger than, smaller than, or identical to BA's local calling areas.

9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance 
                                                           - -
contact numbers, network information, information required to comply with law 
enforcement and other security agencies of the Government) to achieve this 
desired reliability. In addition, the Parties will work cooperatively to apply 
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that 
may be agreed to between the Parties and to employ characteristics and methods 
of operation that will not interfere with or impair the service or any 
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of 
operation used by Party B will or may interfere with or impair its provision of 
services. Party A shall have the right to discontinue Interconnection subject, 
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days prior written 
notice of interference or impairment or potential interference or impairment 
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice 
provided to Party B under (a) above to the appropriate federal and/or state 
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall 
not be required in emergencies and Party A may immediately discontinue 
Interconnection if reasonably necessary to meet its obligations. In such case, 
however, Party A shall use all reasonable means to notify Party B and the 
appropriate federal and/or state regulatory bodies.


<PAGE>
 
          9.3.4 Upon correction of the interference or impairment. Party A will 
promptly renew the Interconnection. During such period of discontinuance, there 
will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

          9.4.1 The Interconnection provided hereunder may be discontinued by 
either Party upon thirty (30) days written notice to the other for repeated or 
willful violation of and/or a refusal to comply with this Agreement. The Party 
discontinuing will notify the appropriate federal and/or state regulatory bodies
concurrently with the notice to the other Party of the prospective 
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility or
service being provided by a Party hereunder, the providing Party will follow
procedures for isolating and clearing the outage or trouble that are no less
favorable than those that apply to comparable arrangements, facilities, or
services being provided by the providing Party to any other carrier whose
network is connected to that of the providing Party. MFS and BA may agree to
modify those procedures from time to time based on their experience with
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES -- SECTION 251(c)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN. On or before December
1, 1996, unless the Parties agree to a different date. MFS and BA shall jointly
develop a grooming plan (the "Joint Plan") which shall define and detail, inter
alia.

          (a)  modifications to the agreement on physical architecture 
     consistent with the guidelines defined in Section 4:

          (b)  standards to ensure that Interconnection trunk groups experience
     a grade of service, availability and quality which is comparable to that
     achieved on interoffice trunks within BA's network and in accord with all
     appropriate relevant industry-accepted quality, reliability and
     availability standards. Trunks provided by either Party for Interconnection
     services will be engineered using a design blocking objective of B.01;

                                      28
<PAGE>
 
               (c)  the respective duties and responsibilities of the Parties
     with respect to the administration and maintenance of the trunk groups,
     including, but not limited to, standards and procedures for notification
     and discoveries of trunk disconnects;
     
               (d)  disaster recovery provision escalations;

               (e)  migration from one-way to two-way Interconnection Trunks
     upon mutual agreement of the Parties;
     
               (f)  actual meet point locations on the SONET system; and

               (g)  such other matter as the Parties may agree. 


     10.2       INSTALLATION, MAINTENANCE, TESTING AND REPAIR. BA's standard
intervals for Feature Group D Switched Exchange Access Services will be used for
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of it facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its
inability to do so and will negotiate such intervals in good faith. The Parties
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than
those applicable to comparable arrangements, facilities, or services being
provided by such Party to any other carrier whose network is connected to that
of the providing Party.

     10.3      FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING.  Within sixty 
(60) days of executing this Agreement, MFS shall provide BA a one (1) year 
traffic forecast. This initial forecast will provide the amount of traffic to be
delivered to each of BA's End Offices affected by the exchange of traffic. The 
forecast shall be updated and provided to BA on a quarterly basis, and include 
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator 
services, 911, etc.), code (identifies trunk group). A location Z location (CLLI
codes), interface type (e.g., DSI), and trunks in service each year 
(cumulative).

               10.3.1 Initial Forecasts/Trunking Requirements.  Because BA's 
                      ---------------------------------------
trunking requirements will, at least during an initial period, be dependent on
the customer segments and service segments within customer segments to whom MFS
decides to market its services. BA will be largely dependent on MFS to provide
accurate trunk forecasts for both inbound (from BA) and outbound (from MFS)
traffic. BA will, as an initial matter and upon request, provide the same number
of trunks to terminate local traffic to MFS as MFS provides to terminate local
traffic to BA, unless MFS expressly identifies particular situations that are
expected to produce traffic that is substantially skewed in either the inbound
or outbound direction, in which case BA will provide the number of trunks MFS
suggests. Upon the establishment of any new set of trunks for traffic from BA to
MFS, BA will monitor traffic for ninety (90) days, and will, as necessary at the
end of that period, either augment trunks or disconnect trunks, based on the
application of reasonable engineering criteria to the actual traffic volume
experienced. If, after such 90-day period, BA has determined that the trunks are
not warranted by actual traffic volumes, then, on ten (10) days' written notice,
BA may hold MFS financially responsible for

  
<PAGE>
 
such trunks retroactive to the start of the 90-day period until such time as 
they are justified by actual traffic volumes, based on the application of 
reasonable engineering criteria. To the extent that BA requires MFS to install 
trunks for delivery of traffic to BA. MFS may apply the same procedures with 
respect to BA's trunking requirements.


11.0 UNBUNDLED ACCESS -- SECTION 251(C)(3).

     To the extent required of each Party by Section 251 of the Act, each Party 
shall offer to the other Party nondiscriminatory access to Network Elements on 
an unbundled basis at any technically feasible point. BA shall unbundle and 
separately price and offer Network Elements such that MFS will be able to lease 
and interconnect to whichever of the Network Elements MFS requires, and to 
combine the BA-provided elements with any facilities and services that MFS may 
itself provide, except that MFS shall not recombine Network Elements purchased 
from BA for use as a substitute for the purchase at wholesale rates of 
Telecommunications Services that BA provides unless otherwise mandated by the 
FCC or the Commission or agreed to by BA with other carriers.

     11.1 UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

     Subject to subsection 11.4, BA shall allow MFS to access the following ULL 
types (in addition to those ULLs available under applicable tariffs) unbundled 
from local switching and local transport in accordance with the terms and 
conditions set forth in this subsection 11.1.

          11.1.1    "2-Wire Analog Voice Grade ULL" or "Analog 2W" provides an 
effective 2-wire channel with 2-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals and 
loop-start signaling. The service is more fully described in Bell Atlantic 
TR-72565. If "Customer-Specified Signaling" is requested, the service will 
operate with one of the following signaling types that may be specified when 
the service is ordered: loop-start, ground-start, loop-reverse-battery, and no 
signaling. The service is more fully described in Bell Atlantic TR-72570.

          11.1.2    "4-Wire Analog Voice Grade ULL" or "Analog 4W" provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The 
service will operate with one of the following signaling types that may be 
specified when the service is ordered: loop-start, ground-start, 
loop-reverse-battery, duplex, and no signaling. The service is more fully 
described in Bell Atlantic TR-72570.

          11.1.3    "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides a 
channel with 2-wire interfaces at each end that is suitable for transport of 160
kbps digital services using the ISDN 2B1Q line code.

          11.1.4    "2-Wire ADSL-Compatible ULL" or "ADSL 2W" provides a channel
with 2-wire interfaces at each end that is suitable for the transport of digital
signals up to 6Mbps toward the Customer and up to 640 kbps from the Customer. BA
will offer ADSL-Compatible

                                      30

<PAGE>
 
ULLs only when the technology BA uses to provide such ULLs is compatible with 
that of MFS. In addition, ADSL-Compatible ULLs will be available only where 
existing copper facilities can meet applicable industry standards.

          11.1.5  "2-Wire HDSL-Compatible ULL" or "HDSL 2W"  provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of 784 
kbps digital signals simultaneously in both directions using the 2B1Q line code.
HDSL compatible ULLs will be available only where existing copper facilities can
meet the specifications.

          11.1.6  "4-Wire HDSL-Compatible ULL" or "HDSL 4W" provides a channel
with 4-wire interfaces at each end. Each 2-wire channel is suitable for the 
transport of 784 kbps digital signals simultaneously in both directions using
the 2B1Q line code. HDSL compatible ULLs will be available only where existing
copper facilities can meet the specifications.

          11.1.7  ULLs will be offered on the terms and conditions specified 
herein and on such other terms in applicable Tariffs that are not inconsistent 
with the terms and conditions set forth herein. BA shall make ULLs available to 
MFS at the rates specified by the Commission, as amended from time to time, 
subject to the provisions of subsection 11.1.8 below. 

          11.1.8  BA will make Analog 2-Wire ULLs available for lease by MFS in 
accordance with the schedule set forth in Schedule 3.0. BA will make BRI ISDN 
and Analog 4W ULLs available for lease by MFS by the later of January 1, 1997, 
or the date when the ULL milestone contained in Schedule 3.0 is achieved in the 
LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease by MFS
as soon as practicable, but in any event no later than six months, after BA 
makes the services using equivalent loop facilities commercially available to 
its own end-user Customers in Virginia. Upon request by either BA or MFS, the 
Parties shall agree upon a reasonable schedule and location for a technical and 
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s) 
may, by mutual agreement, be conducted in any jurisdiction in which affiliates 
of BA and MFS both operate. Upon successful completion of such trial(s), the 
Parties shall agree upon an implementation schedule for the ULL type(s) subject
to such trial(s), which schedule shall begin no later than ninety (90) days 
after successful completion of such trial(s).

     11.2 PORT TYPES

     BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.
                                            ---- ----
<PAGE>
 
     11.3  TRUNK SIDE LOCAL TRANSPORT

     BA shall provide MFS local transport from the trunk side of BA's Central
Office Switches using private lines and special access services unbundled from
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

     11.4  LIMITATIONS ON UNBUNDLED ACCESS

           11.4.1   Unless otherwise mandated by the FCC or the Commission or
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under
applicable tariffs.

           11.4.2   BA shall only be required to make available ULLs and Ports
where such ULLs and Ports are available.

           11.4.3   MFS shall access BA's unbundled Network Elements
specifically identified in this Agreement via Collocation in accordance with
Section 13 at the BA Wire Center where those elements exist and each ULL or
Port shall be delivered to MFS's Collocation by means of a Cross Connection.

           11.4.4   BA shall provide MFS access to its Unbundled Local Loops at
each of BA's Wire Centers for loops terminating in that Wire Center. In
addition, if MFS requests one or more ULLs provisioned via Integrated Digital
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA
shall, where available, move the requested ULL(s) to a spare, existing physical
ULL at no additional charge to MFS. If, however, no spare physical ULL is
available, BA shall within three (3) business days of MFS's request notify MFS
of the lack of available facilities. MFS may then at its discretion make a
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the
ULL concentration site point. Alternatively, MFS may chose to avail itself of
BA's Special Construction services, as set forth in Exhibit A, for the
provisioning of such ULL(s). Notwithstanding anything to the contrary in this
Agreement, the provisioning intervals set forth in subsection 11.6 and the
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this
subsection 11.4.4.

           11.4.5   If MFS orders a ULL type and the distance requested on such
ULL exceeds the transmission characteristics in applicable technical references,
distance extensions may be required and additional rates and charges shall apply
as set forth in Exhibit A or applicable Tariffs.

           11.4.6   BA will exercise all reasonable efforts to ensure that the 
service intervals that apply to ULLs and unbundled Ports are comparable to the 
(i) repair intervals that apply to the bundled dial tone line service, and (ii) 
installation intervals that apply to other BA-

                                      32


<PAGE>
 
coordinated services, except as provided in Section 27. Although BA will make
commercially reasonable efforts to ensure that ULLs and unbundled ports meet
specified or agreed-upon technical standards. BA makes no warranty that the ULLs
or unbundled Ports supplied by BA hereunder will be compatible with the services
MFS may offer to its Customers if they are used in a manner not contemplated by
the Parties.

     11.5  AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

           11.5.1   BA shall, upon request of MFS, and to the extent technically
feasible, provide to MFS access to its Network Elements on an unbundled basis 
for the provision of MFS's Telecommunications Service. Any request by MFS for 
access to an BA Network Element that is not already available shall be treated 
as a Network Element Bona Fide Request. MFS shall provide BA access to its 
Network Elements as mutually agreed by the Parties or as required by the 
Commission or FCC.

           11.5.2.  A Network Element obtained by one Party from the other under
this subsection 11.5 may be used in combination with the facilities of the 
requesting Party only to provide a Telecommunications Service, including
obtaining billing and collection, transmission and routing of the
Telecommunications Service.

           11.5.3   Notwithstanding anything to the contrary in this subsection 
11.5., a Party shall not be required to provide a proprietary Network Element to
the other Party under this subsection 11.5 except as required by the Commission 
or FCC.

     11.6  PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs.  These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA
to MFS and from MFS to BA.

           11.6.1   Upon request by MFS, BA will apply the following
coordination procedures to conversions of live Telephone Exchange Services to
ULLs. Coordinated cutover charges will apply to any such arrangement, only to
the extent provided by Section A.4a of Exhibit A. If MFS elects not to request
coordinated cutover, BA will process MFS's request in the normal course and
subject to the normal installation intervals.

           11.6.2   MFS shall request ULLs from BA by delivering to BA a valid 
electronic transmittal service order (when available) or another mutually agree-
upon type of service order. Such service order shall be provided in accordance
with industry format and specifications or such format and specifications as may
be agreed to by the Parties. Within forty-eight (48) hours of BA's receipt of
such valid service order. Ba shall provide MFS the firm order commitment date
according to the Performance Interval Dates set forth in Schedule 27 by which
the ULLs covered by such service order will be installed. In addition, BA shall
provide MFS with the related ULL design information, if available, at least
forty eight (48) hours prior to the schedule cutover time.

                                      33
<PAGE>
 
     11.6.3  On each ULL order in a Wire Center, MFS and BA will agree on a 
cutover time at least forty eight(48) hours before that cutover time. The 
cutover time will be defined as a 15-30 minute window within which both the MFS 
and BA personnel will make telephone contact to complete the cutover.
  
     11.6.4 Within the appointed 15-30 minute cutover time, the MFS person will
call the BA organization designated to coordinate cross-connection work and when
the BA organization is reached in that interval such work will be promptly
performed. 
 
     11.6.5 If MFS requires a change in scheduling, it must contact BA to issue
a supplement to the original order. The negotiations process to determine the
date and time of cutover will then be reinitiated as usual.

     11.6.6 If the MFS person is not ready within the appointed interval and if
MFS had not called to reschedule the work at least two (2) hours prior to the
start of the interval. MFS shall be liable for the non-recurring charge for the
unbundled elements scheduled for the missed appointment. In addition, non-
recurring charges for the rescheduled appointment will apply.
  
     11.6.7 If BA is not available or not ready at any time during the appointed
15-30 minute interval, MFS and BA will reschedule and BA will waive the non-
recurring charge for the unbundled elements originally scheduled for that
interval, whenever those unbundled elements are actually cut over pursuant to an
agreed-upon rescheduling.
  
     11.6.8  The standard time expected from disconnection of a live Telephone 
Exchange Service to the connection of the unbundled element to the MFS 
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all 
orders consisting of fifteen (15) ULLs or less. Orders involving more than 
fifteen (15) ULLs will require a negotiated interval.
 
     11.6.9 If unusual or unexpected circumstances prolong or extend the time
required to accomplish the coordinated cutover, the Party responsible for such
circumstances is responsible for the reasonable labor charges of the other
Party. Delays caused by the Customer are the responsibility of MFS.
 
     11.6.10 If MFS has ordered INP as part of an ULL installation, BA will
coordinate implementation of INP with the ULL installation. BA's provision of
unbundled elements shall in all cases be subject to the availability of suitable
facilities, to the extent permitted by section 251 of the Act.
 
     11.6.11 If MFS requests or approves a BA technician to perform services on
the network side of the Rate Demarcation Point beyond normal installation of the
ULLs covered by the service order, BA may charge MFS for any additional and
reasonable labor charges to perform such services. BA may also charge MFS its
normal overtime rates for services MFS requests to be performed outside of BA's
normal business hours (M-F. 9am to 5pm. E.S.T.).
 
                                      34

<PAGE>
 
     11.7  MAINTENANCE OF UNBUNDLED LOCAL LOOPS

     If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a dispatch, 
(iii) BA dispatches a technician, and (iv) such trouble was not caused by BA's 
facilities or equipment, then MFS shall pay BA a per-trip charge charge and 
labor charges per quarter hour increments for time associated with said 
dispatch, as set forth in Exhibit A. In addition this charge also applies in 
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA with appropriate dispatch information based on their test results.
If, as the result of MFS instructions, BA is erroneously requested to dispatch
within the Central Office, BA may levy on MFS an appropriate charge.

     11.8  RATES AND CHARGES

     BA shall charge the non-recurring and monthly recurring rates for unbundled
Local Loops and other Network Elements set forth in Exhibit A.

12.0 RESALE -- SECTIONS 251(C)(4) AND 251(B)(1).

     12.1  AVAILABILITY OF RETAIL RATES FOR RESALE

     Each Party shall make available its Telecommunications Services for resale 
at the retail rates set forth in its Tariffs to the other Party in accordance 
with Section 251(b)(1) of the Act. In addition, BA and MFS shall each allow the 
resale by the other of all Telecommunications Services that are offered 
primarily or entirely to other Telecommunications Carriers (e.g., Switched and 
                                                            - -
special Exchange Access Services) at the rates already applicable to such 
services. BA shall also allow the resale by MFS of such other 
non-Telecommunications Services as BA, in its sole discretion, determines to 
provide for resale under terms and conditions to be agreed to by the Parties.

     12.2  AVAILABILITY OF WHOLESALE RATES FOR RESALE

     BA shall make available to MFS for resale all Telecommunications Services 
that BA provides at retail to Customers that are not Telecommunications Carriers
at the retail prices set forth in BA's Tariffs less the wholesale discount set
forth in Exhibit A in accordance with Section 251(c)(4) of the Act. Such 
services shall be provided in accordance with the terms of the applicable retail
services Tariff(s), including, without limitation, user or user group 
restrictions, as the case may be, subject to the requirement that such 
restrictions shall in all cases comply with the requirements of Section 251 of 
the Act and the FCC Regulations regarding restrictions on resale. The Parties
may also agree to negotiate term and or volume discounts for resold services.

     12.3  AVAILABILITY OF SUPPORT SERVICES AND BRANDING FOR RESALE

<PAGE>
 
     BA shall make available to MFS the various support services for resale 
described in Schedule 12.3 hereto in accordance with the terms set forth 
therein. In addition, to the extent required by Applicable Laws, upon request by
MFS and at prices, terms and conditions to be negotiated by MFS and BA. BA shall
provide BA Retail Telecommunications Services (as defined in Schedule 12.3) 
that are identified by MFS's trade name, or that are not identified by trade 
name, trademark or service mark.

     12.4  ADDITIONAL TERMS GOVERNING RESALE AND USE OF BA SERVICES

           12.4.1   MFS shall comply with the provisions of this Agreement
(including, but not limited to, all applicable BA Tariffs) regarding resale or
use of BA services. In addition, MFS shall make reasonable efforts in good faith
to ensure that its Customers comply with the provisions of BA's Tariffs
applicable to their use of BA's Telecommunications Services.

           12.4.2   Without in any way limiting subsection 12.4.1, MFS shall not
resell (a) residential service to business or other nonresidential Customers of
MFS, (b) Lifeline or other means-tested service offerings, or grandfathered
service offerings, to persons not eligible to subscribe to such service
offerings from BA, or (c) any other BA service in violation of any user or user
group restriction that may be contained in the Ba Tariff applicable to such
service to the extent such restriction is not prohibited by Applicable Laws. In
addition, MFS shall be subject to the same limitations that BA's own retail
Customers may be subject to with respect to any Telecommunications Service that
BA may, in its discretion and to the extent not prohibited by Applicable Laws,
discontinue offering. Except as otherwise provided by this Agreement or
Applicable Laws, BA will give MFS notice in writing or electronically (which may
be by giving MFS access to a database or an Internet site that contains the
applicable information, or by other electronic means) of material modification
of the operation, or discontinuance, of BA Retail Telecommunications Services
(as defined in Schedule 12.3) furnished under this Agreement for resale at least
60 days prior to the time the material modification or discontinuance becomes
effective.

           12.4.3   BA shall not be obligated to offer to MFS at a wholesale
discount Telecommunications Services that BA offers at a special promotional
rate if such promotions are for a limited duration of ninety (90) days or less.

           12.4.4   MFS shall provide to BA, in accordance with BA's Tariffs,
adequate assurance of payment of charges due to BA in connection with MFS's
purchase of BA Telecommunications Services for resale. For the purposes of
providing such adequate assurance of payment. MFS shall be deemed to be a
business customer, even if MFS is purchasing Telecommunications Services for
resale to residential customers.

           12.4.5   MFS shall not be eligible to participate in any BA plan or 
program under which BA end user retail Customers may obtain products or 
merchandise, or services which are not Bell Atlantic Retail Telecommunications 
Services (as defined in Schedule 12.3), in return for trying, agreeing to 
purchase, purchasing, or using Bell Atlantic Retail Telecommunications Services.

                                      36

<PAGE>
 
13.0    COLLOCATION -- SECTION 251(c)(6)

        13.1   BA shall offer to MFS Physical Collocation of equipment necessary
for Interconnection (pursuant to Section 4) or for access to unbundled Network
Elements (pursuant to Section 11.0), except that BA may offer only Virtual
Collocation if BA demonstrates to the Commission that Physical Collocation is
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for
the purpose of Interconnection with facilities or services of BA or access to
unbundled Network Elements of BA, except as otherwise mutually agreed to in
writing by the Parties or as required by the FCC or the Commission, subject to
applicable federal and state Tariffs.

        13.2   Although not required to do so by Section 251(c)(6) of the Act,
by this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to
Section 4) on a non-discriminatory basis and at comparable rates, terms and
conditions as MFS may provide to other third parties. MFS shall provide such
Collocation subject to applicable Tariffs.

        13.3   Where MFS is Virtually Collocated on the date hereof on a
premise that was initially prepared for Physical Collocation for MFS, MFS may
elect to (i) retain its Virtual Collocation in that premises, and/or (ii)
establish Physical Collocation in that premises pursuant to current procedures
and applicable Tariffs. BA will not assess to MFS non-recurring charges for
central office common area construction to transition existing virtual
collocation arrangements to physical collocation arrangements in offices where
MFS previously paid such charges. BA will also waive cage construction charges
for cages of the same size originally paid for by MFS. MFS shall coordinate with
BA for rearrangement of MFS's equipment, facilities, and circuits. All
applicable Physical Collocation recurring charges shall apply.

        13.4   Where MFS is Virtually Collocated on the date hereof on a
premise that was initially prepared for MFS as Virtual Collocation, MFS may
elect to (i) retain its Virtual Collocation in that premises, or (ii) unless it
is not practical for technical reasons or because of space limitations, convert
its Virtual Collocation at such premises to Physical Collocation, in which case
MFS shall coordinate the construction and rearrangement with BA of its
equipment, facilities and circuits, and for which MFS shall pay BA at applicable
Tariffs rates. In addition, all Physical Collocation recurring charges shall
apply.

        13.5   For both Physical Collocation and Virtual Collocation, the 
Collocating Party shall provide its own or third-party leased transport 
facilities and terminate those transport facilities in equipment located in its 
Physical Collocation space, or in its virtually collocated equipment, at the 
Housing Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

        13.6   Collocation shall occur under the terms of each Party's
applicable and available Tariffs. Collocation is offered for network
Interconnection between the Parties. Unless otherwise agreed to by the Parties
or either Party is required by applicable law to permit on its collocated

                                      37 

<PAGE>
 
premises, neither Party shall use a Collocation Arrange to directly interconnect
with a third party's equipment or facilities collocated at the same location.

                           SECTION 251(B) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2)

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability
("LTNP") on a reciprocal basis to each other to the extent technically
feasible, and in accordance with rules and regulations as from time to time
prescribed by the FCC and or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the 
industry pursuant to regulations issued by the FCC and/or the Commission, the 
Parties agree to reciprocally provide Interim Number Portability to each other 
at the prices listed in Exhibit A. Such agreed-upon prices for INP  are not 
intended to reflect either Party's views on the cost recovery mechanisms being 
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable 
FCC and/or Commission order(s) or regulations mandating the adoption of a 
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence 
migration from INP  to the agreed-upon or mandated PNP arrangement as quickly as
practically possible while minimizing interruption or degradation of service to 
their respective Customers. Once PNP is implemented, either Party may withdraw, 
at any time and at its sole discretion, its INP offerings, subject to advance 
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant 
to FCC or Commission regulation, both Parties agree to conform and provide such 
PNP. To the extent PNP rates or cost recovery mechanisms are not established by 
the applicable FCC or Commission order or regulation mandating the adoption of 
PNP, the Parties will negotiate in good faith the charges or cost recovery 
mechanism for PNP service at such time as a PNP arrangement is adopted by the 
Parties.

          14.1.4  Under either an INP or PNP arrangement. MFS and BA will 
implement a process to coordinate LTNP cutovers with ULL conversions (as 
described in Section 11 of this Agreement).

     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1  A Customer of one Party ("Party A") elects to become a 
Customer of the other Party ("Party B"). The Customer elects to utilize the 
original telephone number(s)

                                      38
<PAGE>
 
corresponding to the Telephone Exchange Service(s) it previously received from 
Party A in conjunction with the Telephone Exchange Service(s) it will now 
receive from Party B. Upon receipt of a service order from Party B requesting 
assignment of the number(s) to Party B. Party A will implement an arrangement 
whereby all calls to the original telephone number(s) will be forwarded to a 
new telephone number(s) designated by Party B only within the same Exchange Area
as the original telephone number(s). Party A will route the forwarded traffic to
Party B over the appropriate traffic exchange trunk groups.

          14.2.2 Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties. Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3 Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated
with those forwarded numbers as directed by Party B. In addition, Party A will
update the retained numbers in the LIDB with the screening options provided by
Party B on a per order basis. Party B shall determine which of the screening
options offered by Party A should apply to the Party B Customer account.

          14.2.4 Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          14.2.5 Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a 
third party that is authorized to act on behalf of the Customer. Party A shall 
provide notification to Party B of third party orders affecting the INP service 
of a Party B customer. The Parties agree to work cooperatively to develop 
procedures or adopt industry standards or practices concerning the initiation 
and termination of INP service in a multi-carrier environment.

          14.2.6 The INP service offered herein shall not initially apply to NXX
Codes 555,915,976, or 950, or for Feature Group A or coin telephone service. 
Upon request of either Party, provision of INP to these services will be 
mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any 
arrangement that would render the forwarded call Toll Traffic.

          14.2.7 The ordering of INP arrangements and the exchange of screening 
information shall be made in accordance with industry-accepted (e.g. OBF 
developed) format and specifications to the extent they have been implemented by
the Parties.

                                      39
<PAGE>
 
     14.3 PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS 
(FLEXDID) Either Party may also request INP through Direct Inward Dial Trunks 
pursuant to any applicable Tariffs.

     14.4 PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION Where 
either Party has activated an entire NXX for a single Customer, or activated a 
substantial portion of an NXX for a single Customer, with the remaining numbers 
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other 
Party, the first Party shall cooperate with the second Party to have the entire 
NXX reassigned in the LERG (and associated industry databases, routing tables, 
etc.) to an End Office operated by the second Party. Such transfer will be 
accomplished with appropriate coordination between the Parties and subject to 
appropriate industry lead-times for movements of NXXs from one switch to 
another. Neither Party shall charge the other in connection with this 
coordinated transfer.

     14.5 RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described 
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed 
numbers should be received by each Customer's chosen LEC as if each call to the 
Customer had been originally addressed by the caller to a telephone number 
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to 
accomplish this objective where INP is employed, the Parties shall utilize the 
process set forth in this subsection 14.5 whereby terminating compensation on 
calls subject to INP will be passed from the Party (the "Performing Party") 
which performs the INP to the other Party (the "Receiving Party") for whose 
Customer the INP is provided.

          14.5.1 The Parties shall individually and collectively make best
efforts to track and quantify INP traffic between their networks based on the
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving
Party shall charge the Performing Party for each minute of INP traffic at the
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other
compensation charges for terminating such traffic, except as provided in
subsection 14.5.2.
  
          14.5.2 By the Interconnection Activation Date in each LATA, the 
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as
Transit Traffic. On the date which is six (6) months after the Interconnection
Activation Date, and thereafter on each succeeding six month anniversary of
such Interconnection Activation Date, the Parties shall establish new INP
traffic percentages to be applied in the prospective six (6) month period, based
on the Performing Party's choice of actual INP traffic percentages from the
preceding six (6) month period or historic data of all traffic in the LATA.

          14.5.3 The INP Traffic Rate shall be equal to the sum of:

                                      40
<PAGE>
 
     (Recip Traffic percentage times the Reciprocal Compensation Rate set forth
                               -----
     in Exhibit A) 
                                     plus
                                     ----
          (Intra Traffic percentage times Receiving Party's effective intrastate
                                    -----
          FGD rates)
                                     plus
                                     ----
          (Inter Traffic percentage times Receiving Party's effective interstate
                                    -----
          FGD rates)

     The Receiving Party shall compensate the Performing Party for its billing 
and collection of charges for the intrastate and interstate FGD access services
provided by the Receiving Party to a third party through the greater of (i) the
difference between the intrastate and interstate FGD rates of the Receiving
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     14.6 RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this Section 14, in 
light of the FCC's First Report and Order and Further Notice of Proposed 
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the 
Parties stipulate and agree as follows:

          14.6.1    The rates listed in Exhibit A for the provision of INP are 
appropriate amounts that each Party providing INP service should recover for the
provision of those INP functionalities in BA's operating territory. For the INP
functions it provides, each Party should be allowed to recover these amounts in
a manner consistent with any final FCC and/or Commission order or INP cost
recovery (such as a state-wide fund contributed to by all telecommunications
carriers).

          14.6.2    Within three (3) weeks of the Effective Date, the Parties 
will jointly seek a Commission proceeding and ruling to develop and implement an
INP cost recovery mechanism consistent with the policy described in the Order 
and/or any subsequent FCC or Commission decision.

          14.6.3    Until such time as a final FCC and/or Commission order, 
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the Party at the INP rates listed in Exhibit A. All revenues received
by the providing Party from its provision of INP service to the other Party 
shall be placed into an escrow fund maintained by or tracked separately by the 
providing Party. Upon issuance of a final FCC and/or Commission order, and to 
the extent that it permits the Party providing INP to recover the associated 
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal to the amount it recovers from such fund for its provision
of INP service to the purchasing Party from the Effective Date, provided that in
no event shall the refund amount exceed the aggregate amount the providing Party
has received from the purchasing Party for INP services. If no such

     

<PAGE>
 
fund is ordered or established, the providing Party shall retain the full amount
of the revenues tracked or held in escrow by it pursuant to this subsection 
14.6.3.

               14.6.4    The Parties agree that neither Party waives its rights 
to advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.

15.0 DIALING PARTY -- SECTION 251(B)(3).

     BA and MFS shall each provide the other with nondiscriminatory access to 
such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4).

     Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C (S) 
224, as set forth in Exhibit A, where facilities are available, on terms, 
conditions and prices comparable to those offered to any other entity pursuant 
to each Party's applicable Tariffs. Where no such Tariffs exist, such access 
shall be provided in accordance with the requirements of 47 U.S.C (S) 224, 
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C (S)224 
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the 
appropriateness of applying such changes on a retroactive basis to the date 
hereof. If the Parties are unable to agree on the necessary changes to the 
existing arrangements or the appropriateness of applying them on a retroactive 
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.

17.0 DATABASES AND SIGNALING.

     17.1      Each Party shall provide the other Party with access to databases
and associated signaling necessary for call routing and completion by providing 
SS7 Common Channel Signaling (CCS) Interconnection in accordance with existing 
Tariffs, and Interconnection and access to 800/888 databases. LIDB, and any 
other necessary databases in accordance with existing Tariffs and/or agreements 
with other unaffiliated carriers, as set forth in the Exhibit A. Alternatively, 
either Party may secure CCS Interconnection from a commercial SS7 hub provider,
and in that case the other Party will permit the purchasing Party to access the 
same databases as would have been accessible if the purchasing party had 
connected directly to the other Party's CCS network.

                                      42
<PAGE>
 
     17.2 The Parties will provide CCS Signaling to one another, where and as 
available, in conjunction with all Local Traffic, Toll Traffic, Meet Point
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between
their respective networks, including all CLASS features and functions, to the
extent each Party offers such features and functions to its Customers. All CCS
Signaling parameters will be provided upon request (where available), including
called party number, calling party number, originating line information, calling
party category, and charge number. All privacy indicators will be honored. The
Parties will follow all Ordering and Billing Forum-adopted standards pertaining
to CIC/OZZ codes. Where CCS Signaling is not available, in-band multi-frequency
(MF) wink start signaling will be provided. Any such MF arrangement will require
a separate local trunk circuit between the Parties' respective switches. In such
an arrangement, each Party will outpulse the full ten-digit telephone number of
the called party to the other Party.

     17.3 Each Party shall provide trunk groups, where available and upon 
reasonable request, that are configured utilizing the B8ZS ESF protocol for 64 
kbps clear channel transmission to allow for ISDN interoperability between the 
Parties' respective networks.

     17.4 The following publications describe the practices, procedures and 
specifications generally utilized by BA for signaling purposes and is listed 
herein to assist the Parties in meeting their respective Interconnection 
responsibilities related to Signaling:

          (a)  Bellcore Special Report SR-TSV-002275. BOC Notes on the LEC 
Networks - Signaling; and

          (b)  Bell Atlantic Supplement Common Channel Signaling Network 
Interface Specification (BA-905).

     17.5 Each Party shall charge the other Party mutual and reciprocal rates 
for CCS Signaling as follows: BA shall charge MFS in accordance with Exhibit A 
hereto and applicable Tariffs: MFS shall charge BA rates equal to the rates BA 
charges MFS, unless MFS's Tariffs for CCS signaling provide for lower generally 
available rates, in which case MFS shall charge BA such lower rates.

18.0 COORDINATED SERVICE ARRANGEMENTS.

     18.1 INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its 
service provider from BA to MFS, or from MFS to BA, and does not retain its 
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides details on the Customer's new number or provide 
other appropriate information to the extent known. Referral Announcements shall 
be provided reciprocally, free of charge to either the other Party or the 
Customer to the extent the providing Party does not charge its own customers for

<PAGE>
 
such service, for a period of not less than four (4) months after the date the 
Customer changes its telephone number in the case of business Customers and not 
less than sixty (60) days after the date the Customer changes its telephone 
number in the case of residential Customers. However, if either Party provides 
Referral Announcements for different periods than the above respective periods 
when its Customers change their telephone numbers, such Party shall provide the 
same level of service to Customers of the other Party.

     18.2  COORDINATED REPAIR CALLS. MFS and BA will employ the following 
procedures for handling misdirected repair calls:

           18.2.1  MFS and BA will educate their respective Customers as to the 
correct telephone numbers to call in order to access their respective repair 
bureaus.

           18.2.2  To the extent Party A is identifiable as the correct provider
of service to Customers that make misdirected repair calls to Party B. Party B
will immediately refer the Customers to the telephone number provided by Party
A, or to an information source that can provide the telephone number of Party A,
in a courteous manner and at no charge. In responding to misdirected repair
calls, neither Party shall make disparaging remarks about the other Party, its
services, rates, or service quality.

           18.2.3  MFS and BA will provide their respective repair contact 
numbers to one another on a reciprocal basis.

     18.3  CUSTOMER AUTHORIZATION. In order for either Party to order or 
terminate service on behalf of the other Party's Customer, the requesting Party 
must have proper written authorization from the customer in its files, and 
provide a copy of such authorization to the other Party upon request. In the 
event the requesting Party (i) fails to provide a copy of the Customer's proper 
written authorization upon request, (ii) requests changes in the other Party's 
Customer's service without having such authorization in its files, or (iii) 
mistakenly changes the other Party's Customer's service, the requesting Party 
shall be liable to the other Party for all charges that would be applicable to 
the Customer for restoring service to the other Party.


19.0  DIRECTORY SERVICES ARRANGEMENTS

      BA will, upon request, provide the following directory services to MFS in 
accordance with the terms set forth herein. In this Section 19, references to a 
MFS Customer's "primary listing" shall mean such Customer's name, address, and 
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP 
arrangements with BA or any other carrier within the geographic area covered in 
the relevant BA directory.

      19.1  DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

                                      44



<PAGE>
 
          19.1.1   BA will include the MFS Customer's primary listing in its 
"White Pages" directory (residence and business listings) and "Yellow Pages" 
directory (business listings) that cover the address of the Customer. Listings 
of MFS's Customers will be interfiled with listings of BA's Customers and the 
Customers of other LECs included in the BA directories. MFS will pay BA a 
non-recurring charge as set forth in Exhibit A for providing such service for 
each MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as
the case may be, for additional and foreign white page listings and other white 
pages services for MFS's Customers. BA will not require a minimum number of 
listings per order.

          19.1.2   BA will also include the MFS Customer's primary listing in 
BA's directory assistance database on the same basis that BA's own Customers 
are included, as well as in any electronic directories in which BA's Customers 
are ordinarily included, for no charge other than the charges identified in 
subsection 19.1.1.

          19.1.3   BA will distribute to MFS Customers copies of their primary 
white pages and yellow pages directories at the same time and on the same basis 
that BA distributes primary directories to its own Customers. BA will also 
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional 
directories from BA's Directory Fulfillment Centers, which Centers will provide 
such additional directories for the same charges applicable to comparable 
requests by BA Customers.

          19.1.4   BA will include all MFS NXX codes associated with the areas 
to which each directory pertains, along with BA's own NXX codes in any maps or 
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same 
manner as BA's NXX information.

          19.1.5   MFS shall provide BA with daily listing information on all 
new MFS Customers in the format required by BA or a mutually-agreed upon 
industry standard format. The information shall include the Customer's name, 
address, telephone number, the delivery address and number of directories to be 
delivered, and, in the case of a business listing, the primary business heading 
under which the business Customer desires to be placed, and any other 
information necessary for the publication and delivery of directories. MFS will 
also provide BA with daily listing information showing Customers that have 
disconnected or terminated their service with MFS. BA will provide MFS with 
confirmation of listing order activity within forty eight (48) hours.

          19.1.6   BA will accord MFS's directory listing information the same 
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be 
used solely for the purpose of providing directory services: provided, however, 
that BA may use or license information contained in its directory listings for 
direct marketing purposes so long as the MFS Customers are not separately 
identified as such: and provided further that MFS may identify those of its 
Customers that request that their names not be sold for direct marketing 
purposes, and BA will honor such requests to the same extent as it does for its 
own Customers.


<PAGE>
 
           19.1.7   BA or BA's publisher shall provide MFS with a report of all 
MFS Customer listings ninety (90) days prior to directory publication in such 
form and format as may be mutually agreed to by both Parties. Both Parties shall
use their best efforts to ensure the accurate listing of such information. BA
will also provide MFS, upon request, a copy of the BA listings standards and
specifications manual. In addition, BA will provide MFS with a listing of Yellow
Pages headings and directory close schedules on an ongoing basis.

           19.1.8   MFS will adhere to all practices, standards, and ethical 
requirements of BA with regard to listings, and, by providing BA with listing 
information, warrants to BA that MFS has the right to place such listings on 
behalf of its Customers. MFS agrees that it will undertake commercially 
practicable and reasonable steps to attempt to ensure that any business or 
person to be listed is authorized and has the right (i) to provide the product 
or service offered, and (ii) to use any personal or corporate name, trade name 
or language used in the listing.

           19.1.9   BA's liability to MFS in the event of a BA error in or 
omission of a listing shall be subject to the same limitations that BA's 
liability to its own Customers are subject to. In addition, MFS agrees to take, 
with respect to its own Customers, all reasonable steps to ensure that its and 
BA's liability to MFS's Customers in the event of a BA error in or omission of a
listing shall be subject to the same limitations that BA's liability to its own 
Customers are subject to.

     19.2  YELLOW PAGE MAINTENANCE. The Parties agree to work cooperatively to 
ensure that Yellow Page advertisements purchased by Customers that switch their 
service to MFS (including Customers utilizing MFS-assigned telephone numbers and
MFS Customers utilizing LTNP) are maintained without interruption. BA will allow
MFS Customers to purchase new Yellow Pages advertisements without 
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. BA and MFS may implement a commission program whereby MFS may, at 
MFS's sole discretion, act as a sales, billing and collection agent for Yellow 
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

     19.3  SERVICE INFORMATION PAGES. BA will include in the "Customer Guide" or
comparable section of the applicable white pages directories listings provided
by MFS for MFS's installation, repair and customer service and other essential
service oriented information, as agreed by the Parties, including appropriate
identifying logo. Such listings shall appear in the manner agreed to by the
Parties. BA shall not charge MFS for inclusion of this essential service-
oriented information, but reserves the right to impose charges on other
information MFS may elect to submit and BA may elect to accept for inclusion in
BA's white pages directories. BA will provide MFS with the annual directory
close dates and reasonable notice of any changes in said dates.

     19.4  DIRECTORY ASSISTANCE (DA); CALL COMPLETION

           19.4.1   Upon request, BA will provide MFS with directory assistance 
and/or call completion services substantially in accordance with the terms set 
forth in the form Directory Assistance and Call Completion Services Agreement 
appended hereto as EXhibit C.

                                      46

<PAGE>
 
            19.4.2 Also upon request, BA will provide to MFS operator services
trunk groups, utilizing Feature Group D type signaling, with ANI, minus OZZ,
when interconnecting to the BA operator services network.


20.0  COORDINATION WITH TARIFF TERMS

      20.1  The Parties acknowledge that some of the services, facilities, and 
arrangements described herein are or will be available under and subject to the 
terms of the federal or state tariffs of the other Party applicable to such 
services, facilities, and arrangements. To the extent a Tariff of the providing 
Party applies to any service, facility, and arrangement described herein, the 
Parties agree as follows:

            20.1.1  Those rates and charges set forth in Exhibit A for the 
services, facilities and arrangements described herein that are designated with 
an asterisk shall remain fixed for the initial term of the Agreement, 
notwithstanding that such rates may be different from those contained in an 
effective, pending, or future Tariff of the providing Party (including any 
changes to such Tariff subsequent to the Effective Date). Those rates and 
charges for services, facilities and arrangements that are not designated with 
an asterisk, and reference or are identical to a rate contained in an existing 
Tariff of the providing Party, shall conform with those contained in the 
then-prevailing Tariff and vary in accordance with any changes that may be made 
to the Tariff rates and charges subsequent to the Effective Date. Even the 
asterisked fixed rates and charges shall be changed to reflect any changes in 
the Tariff rates and charges they reference, however, if the Parties agree to 
adopt the changed Tariff rates and charges.

      20.2  Except with respect to the rates and charges described in subsection
20.1 above, all other terms contained in an applicable Tariff of the providing 
Party shall apply in connection with its provision of the particular service, 
facility, and arrangement hereunder.


21.0  INSURANCE

      21.1  MFS shall maintain, during the term of this Agreement, all insurance
and/or bonds required by law and necessary to satisfy its obligations under this
Agreement, including, without limitation, its obligations set forth in Section 
25 hereof. At a minimum and without limiting the foregoing covenant, MFS shall 
maintain the following insurance:

            (a)  Commercial General Liability Insurance, on an occurrence basis,
      including but not limited to, premises-operations, broad form property
      damage, products/completed operations, contractual liability, independent
      contractors, and personal injury, with limits of at least $1,000,000
      combined single limit for each occurrence.

            (b)  Automobile Liability, Comprehensive Form, with limits of at 
      least $500,000 combined single limit for each occurrence.
<PAGE>
 
            (c)   Excess Liability, in the umbrella form, with limits of at 
      least $15,000,000 combined single limit for each occurrence.

            (d)   Worker's Compensation Insurance as required by law and
      Employer's Liability Insurance with limits of not less than $1,000,000 per
      occurrence.

      21.2  MFS shall name BA as an additional insured on the foregoing 
insurance. MFS agrees that MFS's insurer(s) and anyone claiming by, through, 
under or on behalf of MFS, shall have no claim, right of action, or right of 
subrogation, against BA. BA's affiliated companies, or the directors, officers 
or employees of BA or BA's affiliated companies, based on any loss or liability 
insurable under the foregoing insurance.

      21.3  MFS shall within two (2) weeks of the date hereof and on a quarterly
basis thereafter, furnish certificates or other adequate proof of the foregoing
insurance. The certificates or other proof of the foregoing insurance shall be
sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court House
Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall require its
agents, representatives, or contractors, if any, that may enter upon the
premises of BA or BA's affiliated companies to maintain similar and appropriate
insurance and, if requested, to furnish BA certificates or other adequate proof
of such insurance. Certificates furnished by MFS or MFS's agents,
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to
cancellation of, or any material change in, the insurance."



22.0  TERM AND TERMINATION

      22.1  This Agreement shall be effective as of the date first above written
and continue in effect until July 1, 1999, and thereafter the Agreement shall 
continue in force and effect unless and until terminated as provided herein. 
Upon the expiration of the initial term, either Party may terminate this 
Agreement by providing written notice of termination to the other Party, such 
written notice to be provided at least ninety (90) days in advance of the date 
of termination. In the event of such termination, those service arrangements 
made available under this Agreement and existing at the time of termination 
shall continue without interruption under (a) a new agreement executed by the 
Parties, (b) standard Interconnection terms and conditions approved and made 
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of 
this Agreement on a month-to-month basis until such time as (a), (b), or (c) 
becomes available.

      22.2  For service arrangements made available under this Agreement and 
existing at the time of termination, if the standard Interconnection terms and 
conditions or Tariff terms and conditions result in the non-terminating Party 
physically rearranging facilities or incurring programming expense, the 
non-terminating Party shall be entitled to recover such rearrangement or 
programming costs, from the terminating Party. By mutual agreement, the Parties 
may jointly petition the appropriate regulatory bodies for permission to have 
this Agreement supersede any future standardized agreements or rules as such 
regulators might adopt or approve.

                                      48
<PAGE>
 
     22.3  If either Party defaults in the payment of any amount due hereunder,
or if either Party violates any other provision of this Agreement, and such
default or violation shall continue for sixty (60) days after written notice
thereof, the other Party may terminate this Agreement and services hereunder by
written notice; provided the other Party has provided the defaulting Party and
the appropriate federal and/or state regulatory bodies with written notice at
least twenty five (25) days' prior to terminating service. Notice shall be
posted by certified mail, return receipt requested. If the defaulting Party
cures the default or violation within the twenty five (25) day period, the other
Party will not terminate service or this Agreement but shall be entitled to
recover all costs, if any, incurred by it in connection with the default or
violation, including, without limitation, costs incurred to prepare for the
termination of service.

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES ANY 
WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND 
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE PARTIES 
DISCLAIM THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A 
PARTICULAR PURPOSE.

24.0 CANCELLATION CHARGES.

     Except as provided in this Agreement or as otherwise provided in any 
applicable Tariff, no cancellation charges shall apply.

25.0 INDEMNIFICATION.

     25.1   Each Party agrees to release, indemnify, defend and hold harmless 
the other Party from and against all losses, claims, demands, damages, expenses,
suits or other actions, or any liability whatsoever, including, but not limited 
to, costs and attorneys' fees (collectively, a "Loss"), (a) whether suffered, 
made, instituted, or asserted by any other party or person, (i) relating to 
personal injury to or death of any person, or for loss, damage to, or 
destruction of real and/or personal property, whether or not owned by others, 
incurred during the term of this Agreement and to the extent proximately caused 
by the acts or omissions of the indemnifying Party, regardless of the form of
action, or (ii) arising out of BA's listing of the directory listing information
provided by MFS pursuant to subsection 19.1 or (b) suffered, made, instituted, 
or asserted by its own customer(s) against the other Party arising out the 
Party's provision of services to the indemnifying Party under this Agreement. 
Notwithstanding the foregoing indemnification, nothing in this such Section 25,
shall affect or limit any claims, remedies, or other actions the indemnifying 
Party may have against the indemnified Party under this Agreement, any other 
contract, or any applicable Tariff(s), regulations or laws for the indemnified 
Party's provision of said services.
<PAGE>
 
     25.2 The indemnification provided herein shall be conditioned upon:

          (a)  The indemnified Party shall promptly notify the indemnifying 
     Party of any action taken against the indemnified Party relating to the 
     indemnification.

          (b)  The indemnifying Party shall have sole authority to defend any 
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c)  In no event shall the indemnifying Party settle or consent to any
     judgement pertaining to any such action without the prior written consent
     of the indemnified Party, which consent shall not be unreasonably withheld.

          (d)  The indemnified Party shall, in all cases, assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e)  The indemnified Party shall offer the indemnifying Party all
     reasonable cooperation and assistance in the defense of any such action.

     25.3 In addition to its indemnity obligations under subsection 25.1, each 
Party shall provide, in its tariffs and contracts with its Customers that relate
to any Telecommunications Service or Network Element provided or contemplated 
under this Agreement, that in no case shall such Party or any of its agents,
contractors or others retained by such parties be liable to any Customer or
third party for (i) any Loss relating to or arising out of this Agreement,
whether in contract or tort, that exceeds the amount such Party would have
charged the applicable Customer for the service(s) or function(s) that gave rise
to such Loss, and (ii) any Consequential Damages (as defined in subsection 26.2
below).

26.0 LIMITATION OF LIABILITY.

     26.1 Except as may be provided pursuant to Section 27 below, the liability
of either Party to the other Party for damages arising out of failure to comply
with a direction to install, restore or terminate facilities: or out of
failures, mistakes, omissions, interruptions, delays, errors, or defects
occurring in the course of furnishing any services, arrangements, or facilities
hereunder shall be determined in accordance with the terms of the applicable
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro rata monthly
charge for the period in which such failures, mistakes, omissions,
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for
such failures, mistakes, omissions, interruptions, delays, errors or defects.

     26.2 Neither Party shall be liable to the other in connection with the 
provision or use of services offered under this Agreement for indirect, 
incidental, consequential, reliance or special

                                      50
<PAGE>
 
damages, including (without limitation) damages for lost profits (collectively, 
"Consequential Damages"), regardless of the form of action, whether in contract 
warranty, strict liability, or tort, including, without limitation, negligence 
of any kind, even if the other Party has been advised of the possibility of such
damages; provided, that the foregoing shall not limit a Party's obligation under
Section 25.

     26.3 The Parties agree that neither Party shall be liable to the customers
of the other Party in connection with its provision of services to the other
Party under this Agreement. Nothing in this Agreement shall be deemed to create
a third party beneficiary relationship between the Party providing the service
and the customers of the Party purchasing the service. In the event of a
dispute involving both Parties with a customer of one Party, both Parties shall
assert the applicability of any limitations on liability to customers that may
be contained in either Party's applicable Tariff(s).

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

     27.1 CERTAIN DEFINITIONS. When used in this Section 27, the following terms
shall have the meanings indicated:

          27.1.1  "Specified Performance Breach" means the failure by BA to
meet the Performance Criteria for any of the three Specified Activities for a
period of three (3) consecutive calendar months.
     
          27.1.2  "Specified Activity" means any of the following activities:

          (a)     the installation by BA of Unbundled Local Loop ELements for 
     MFS ("ULL Installation");

          (b)     BA's provision of INP to MFS or

          (c)     repair of out of service problems for MFS ("Out of Service 
     Repairs").

          27.1.3  "Performance Criteria" means, with respect to any calendar
month during the term of this Agreement, the performance by BA during such month
of each Specified Activity (except Out-of-Service Repairs) shown in Schedule
27.0. within the time interval shown in at least eighty percent (80%) of the
covered instances. BA shall perform the Out-of-Service Repairs within the
specified time interval in at least seventy percent (70%) of the covered
instances. Within one week of each anniversary of the Effective Date, the
Parties shall jointly review BA's actual network-wide monthly performance
percentages for Out-of-Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual
percentages for any three consecutive month period and/or the full preceding
year, up to and including an eighty percent (80%) standard as the Out-of-Service
Repairs percentage standard applicable to the following year.

                                      51

<PAGE>
 
     27.2  PERFORMANCE STANDARDS.  BA shall exercise best efforts to meet the 
Performance Criteria for the three Specified Activities. In the event BA fails 
to meet the Performance Criteria at any time during the term of this Agreement.
MFS shall be entitled to pursue all remedies set forth in the applicable BA
Tariffs, except as may be agreed to by the Parties. In addition, if BA commits a
Specified Performance Breach during the term of this Agreement, the Parties
agree to meet immediately to determine whether any liquidated damages provisions
are appropriate as an amendment hereof in light of such Breach and, if so, the
terms therein; provided, however, that if BA commits a Specified Performance
Breach during initial nine (9) months of this Agreement, the Parties agree to
meet at the end of the nine-month period. If the Parties are unable to agree as
to the appropriateness of the liquidated damages provisions and or the terms
therein within ninety (90) days after the date of the first meeting pursuant to
this subsection, or if no such meeting has occurred within ninety (90) days of
the end of the nine-month period for reasons other than the mutual agreement of
the Parties, the Parties agree to submit to arbitration such disagreement and
request that the arbitrators base their decision on comparable ILEC-CLEC
interconnection agreements. Unless otherwise agreed to by the Parties, the
arbitration shall be conducted by a panel of three (3) arbitrators, one to be
appointed by each Party pursuant to CPR's Non-Administered Arbitration Rules and
subject to the United States Arbitration Act (9 U.S.C. (S)(S) 1-16), to be
conducted in Arlington, Virginia. The Parties agree that the liquidated damages
provisions, if any, finally determined by the arbitral process shall be adopted
as an amendment to this Agreement.

     27.3  LIMITATIONS.  In no event shall BA be deemed to have failed to meet 
any of the Performance Criteria if:

           27.3.1   BA's failure to meet or exceed any of the Performance 
Criteria is caused, directly or indirectly, by a Delaying Event. A "Delaying 
Event" means (a) a failure by MFS to perform any of its obligations set forth in
this Agreement (including, without limitation, the Implementation Schedule and 
the Joint Grooming Plan), (b) any delay, act or failure to act by a Customer, 
agent, representative, or subcontractor of MFS or (c) any Force Majeure Event. 
If a Delaying Event prevents or delays BA from performing a Specified Activity, 
then such Specified Activity shall be excluded from the calculation of BA's 
compliance with the Performance Criteria, provided BA performs the Specified 
Activity in the course of its normal service cycle once the Delaying Event no 
longer exists; or

           27.3.2   the Parties agree to a time interval with respect to a
particular order that exceeds the interval set form in Schedule 27. In such
event, the time interval for BA's performance of the Specified Activit(ies) set
forth in the order shall be extended to such later date agreed to by the
Parties.

     27.4  SERVICE QUALITY STANDARDS.  MFS agrees to specific performance 
standards associated with quality of service requests as specified in Schedule 
27.1. Should MFS fail to meet these service quality standards, during a period 
in which BA has failed to meet the Performance Criteria. BA's failure during
such time period shall be excused and not apply toward the calculation of a
Specified Performance Breach.

                                      52
     
<PAGE>
 
     27.5 RECORDS. Each Party shall maintain complete and accurate records in 
the manner and format agreed to by the Parties, on a monthly basis, of BA's 
performance under this Agreement of each Specified Activity and its compliance 
with the Performance Criteria during the initial nine-month period. Each Party 
shall provide to the other Party such records in a self-reporting format on a 
monthly basis. The Parties agree that such records shall be deemed "Proprietary 
Information" for purposes of subsection 29.4.

28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

     28.1 Each Party represents and warrants that it is now and will remain in 
compliance with all laws, regulations, and orders applicable to performance of 
its obligations hereunder (collectively, "Applicable Laws"). Each Party shall 
promptly notify the other Party in writing of any governmental action that 
suspends, cancels, withdraws, limits, or otherwise materially affects its 
ability to perform its obligations hereunder.

     28.2 The Parties understand and agree that this Agreement will be filed 
with the Commission and may thereafter be filed with the FCC. The Parties  
covenant and agree that this Agreement is satisfactory to them as an agreement 
under Section 251 of the Act. Each Party covenants and agrees to fully support 
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek 
regulatory relief and otherwise seek redress from each other regarding 
performance and implementation of this Agreement.

     28.3 The Parties recognize that the FCC is currently promulgating 
regulations implementing the Act, including, without limitation, Section 251, 
252, and 271 thereof (the "FCC Regulations"), that may affect the terms 
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties 
agree to make only the minimum revisions necessary to eliminate the 
inconsistency. Such minimum changes to conform this Agreement to the FCC 
Regulations shall not be considered material, and shall not require further 
Commission approval (beyond any Commission approval required under Section 
252(e) of the Act).

     28.4 In the event any Applicable Laws other than the FCC Regulations 
requires modification of any material term(s) contained in this Agreement, 
either Party may require a renegotiation of the term(s) that require direct 
modification as well as of any term(s) that are reasonably affected thereby. If 
neither Party requests a renegotiation or if an Applicable Laws requires 
modification of any non-material term(s), then the Parties agree to make only 
the minimum modifications necessary, and the remaining provisions of this 
Agreement shall remain in full force and effect. For purposes of this subsection
28.4 and without limitation of any other modifications required by Applicable 
Laws, the Parties agree that any modification required by Applicable Laws (i) to
the two-tier Reciprocal Call Termination compensation structure for the 
transport and termination of Local Traffic described in Exhibit A, or (ii) that 
affects either Party's receipt of reciprocal compensation for the transport and 
termination of Local Traffic, shall be deemed to be a modification of a material
term that requires immediate good faith renegotiation between the Parties.

                                      53
     
<PAGE>
 
Until such renegotiation results in a new agreement or an amendment to this
Agreement between the Parties, the Parties agree that (y) in the case of (i)
above, they will pay each other appropriate transport charges in addition to the
usual call termination charge for Local Traffic that it delivers to the other
Party's Local Serving Wire Center, provided each Party continues to offer the
option of delivering Local Traffic to another IP in the LATA at the usual call
termination charge only, and (z) in the case of (ii) above, the Party whose
receipt of reciprocal compensation is affected shall not be obligated to pay the
other Party reciprocal compensation for the other Party's transport and
termination of the same kind of Local Traffic delivered by the affected Party in
excess of what the affected Party is permitted to receive and retain.



29.0 MISCELLANEOUS.

     29.1 AUTHORIZATION.

          29.1.1  BA is a corporation duly organized, validly existing and in 
good standing under the laws of the Commonwealth of Virginia and has full power 
and authority to execute and deliver this Agreement and to perform the 
obligations hereunder on behalf of BA.

          29.1.2  MFS is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware and has full power and 
authority to execute and deliver this Agreement and to perform its obligations 
hereunder.

     29.2 INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder 
as an independent contractor and nothing herein shall be construed as creating 
any other relationship between the Parties. Each Party and each Party's 
contractor shall be solely responsible for the withholding or payment of all 
applicable federal, state and local income taxes, social security taxes and 
other payroll taxes with respect to their employees, as well as any taxes, 
contributions or other obligations imposed by applicable state unemployment or 
workers' compensation acts. Each Party has sole authority and responsibility to 
hire, fire and otherwise control its employees.

     29.3  FORCE MAJEURE. Neither Party shall be responsible for delays or 
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in 
performance were foreseen or foreseeable as of the date of this Agreement, 
including, without limitation; adverse weather conditions, fire, explosion, 
power failure, acts of God, war, revolution, civil commotion, or acts of public 
enemies; any law, order, regulation, ordinance or requirement of any government 
or legal body; or labor unrest, including, without limitation, strikes, 
slowdowns, picketing or boycotts; or delays caused by the other Party or by 
other service or equipment vendors; or any other circumstances beyond the 
Party's reasonable control. In such event, the affected Party shall, upon giving
prompt notice to the other Party, be excused from such performance on a 
day-to-day basis to the extent of such interferences (and the other Party shall 
likewise be excused from performance of its obligations on a day-to-day basis to
the extent such Party's obligations relate to the performance so interfered 
with). The affected Party shall use its best efforts to avoid or remove the 
cause(s) of non-

                                      54
<PAGE>
 
performance and both Parties shall proceed to perform with dispatch once the 
cause(s) are removed or cease.

     29.4 CONFIDENTIALITY.

          29.4.1 All information, including but not limited to specification,
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches,
models, samples, tools, technical information, data, employee records, maps,
financial reports, and market data, (i) furnished by one Party to the other
Party dealing with customer specific, facility specific, or usage specific
information, other than customer information communicated for the purpose of
publication or directory database inclusion, or (ii) in written, graphic,
electromagnetic, or other tangible form and marked at the time of delivery as
"Confidential" or "Proprietary," or (iii) communicated orally and declared to
the receiving Party at the time of delivery, or by written notice given to the
receiving Party within ten (10) days after delivery, to be "Confidential" or
"Proprietary" (collectively referred to as "Proprietary Information"), shall
remain the property of the disclosing Party.

          29.4.2  Each Party shall keep all of the other Party's Proprietary 
Information confidential and shall use the other Party's Proprietary Information
only for performing the covenants contained in this Agreement. Neither Party 
shall use the other Party's Proprietary Information for any other purpose except
upon such terms and conditions as may be agreed upon between the Parties in 
writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality 
and non-use set forth in this Agreement do not apply to such Proprietary 
Information that:

          (a)     was, at the time of receipt, already known to the receiving 
Party free of any obligation to keep it confidential as evidenced by written 
records prepared prior to delivery by the disclosing Party; or

          (b)     is or becomes publicly known through no wrongful act of the 
receiving Party; or

          (c)     is rightfully received from a third person having no direct 
or indirect secrecy or confidentiality obligation to the disclosing Party with 
respect to such information; or

          (d)     is independently developed by an employee agent, or
contractor of the receiving Party that is not involved in any manner with the
provision of services pursuant to this Agreement and does not have any direct or
indirect access to the Proprietary Information; or

          (e)     is approved for release by written authorization of the 
disclosing Party; or

          (f)     is required to be made public by the receiving Party pursuant
to applicable law or regulation, provided that the receiving Party shall give
sufficient notice of the requirement to the disclosing Party to enable the
disclosing Party to seek protective orders.


                                      55
<PAGE>
 
          29.4.4 Upon request by the disclosing Party, the receiving Party shall
return all tangible copies of Proprietary Information, whether written, graphic
or otherwise, except that the receiving Party may retain one copy for archival
purposes only.

          29.4.5 Notwithstanding any other provision of this Agreement, the 
provisions of this subsection 29.4 shall apply to all Proprietary Information 
furnished by either Party to the other in furtherance of the purpose of this 
Agreement, even if furnished before the Effective Date.

       29.5 CHOICE OF LAW.  The construction, interpretation and performance of
this Agreement shall be governed by and construed in accordance with the laws of
the state in which this Agreement is to be performed except for its conflicts of
laws provisions. In addition, insofar as and to the extent federal law may
apply, federal law will control.

       29.6  TAXES

               29.6.1. In General. With respect to any purchase hereunder of 
                       ----------
services, facilities or arrangements, if any federal, state or local tax, fee, 
surcharge or other tax-like charge (a "Tax") is required or permitted by 
Applicable Laws (as defined in subsection 28.1) to be collected from the
purchasing Party by the providing Party, then (i) the providing Party shall
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

               29.6.2. Taxes Imposed on the Providing Party. With respect to any
                       ------------------------------------
purchase hereunder of services, facilities or arrangements, if any federal, 
state or local Tax is imposed by Applicable Laws on the receipts of the 
providing Party, which Law permits the providing Party to exclude certain 
receipts received from sales for resale to a public utility, distributor, 
telephone company, local exchange carrier, telecommunications company or other 
communications company ("Telecommunications Company"), such exclusion being 
based solely on the fact that the purchasing Party is also subject to a tax 
based upon receipts ("Receipts Tax"), then the purchasing Party (i) shall 
provide the providing Party with notice in writing in accordance with 
subsection 29.6.6 of this Agreement of its intent to pay the Receipts Tax and 
(ii) shall timely pay the Receipts Tax to the applicable tax authority.

               29.6.3. Taxes Imposed on Customers. With respect to any purchase 
                       -------------------------- 
hereunder of services, facilities or arrangements that are resold to a third 
party, if any federal, state or local Tax is imposed by Applicable Laws on the 
subscriber, end-user, Customer or ultimate consumer ("Subscriber") in connection
with any such purchase, which a Telecommunications Company is required to impose
and/or collect from a Subscriber than the purchasing Party (i) shall be required
to impose and/or collect such Tax from the Subscriber and (ii) shall timely
remit such Tax to the applicable taxing authority.

               29.6.4 Liability for Uncollected Tax, Interest and Penalty. If 
                      ---------------------------------------------------
the providing Party has not received an exemption certificate and fails to 
collect any Tax as required by subsection

                                      56
<PAGE>
 
29.6.1. then, as between the providing Party and the purchasing Party, (i) the 
purchasing Party shall remain liable for such uncollected Tax and (ii) the 
providing Party shall be liable for any interest assessed thereon and any 
penalty assessed with respect to such uncollected Tax by such authority. If the 
providing Party properly bills the purchasing Party for any Tax but the 
purchasing Party fails to remit such Tax to the providing Party as required by 
subsection 29.6.1, then, as between the providing Party and the purchasing 
Party, the purchasing Party shall be liable for such uncollected Tax and any 
interest assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. If the providing Party does 
not collect any Tax as required by subsection 29.6.1 because the purchasing 
Party has provided such providing Party with an exemption certificate that is 
later found to be inadequate by a taxing authority, then, as between the 
providing Party and the purchasing Party, the purchasing Party shall be liable 
for such uncollected Tax and any interest assessed thereon, as well as any 
penalty assessed with respect to such uncollected Tax by the applicable taxing 
authority. If the purchasing Party fails to pay the Receipts Tax as required by 
subsection 29.6.2, then, as between the providing Party and the purchasing 
Party, (x) the providing Party shall be liable for any Tax imposed on its 
receipts and (y) the purchasing Party shall be liable for any interest assessed 
thereon and any penalty assessed upon the providing Party with respect to such 
Tax by such authority. If the purchasing Party fails to impose and or collect 
any Tax from Subscribers as required by subsection 29.6.3 then, as between the 
providing Party and the purchasing Party, the purchasing Party shall remain 
liable for such uncollected Tax and any interest assessed thereon, as well as 
any penalty assessed with respect to such uncollected Tax by the applicable 
taxing authority. With respect to any Tax that the purchasing Party has agreed 
to pay, or is required to impose on and/or collect from Subscribers, the 
purchasing Party agrees to indemnify and hold the providing Party harmless on an
after-tax basis for any costs incurred by the providing Party as a result of 
actions taken by the applicable taxing authority to recover the Tax from the 
providing Party due to the failure of the purchasing Party to timely pay, or 
collect and timely remit, such Tax to such authority. In the event either Party 
is audited by a taxing authority, the other Party agrees to cooperate fully with
the Party being audited in order to respond to any audit inquiries in a proper 
and timely manner so that the audit and/or any resulting controversy may be 
resolved expeditiously.

          29.6.5.   Tax Exemptions and Exemption Certificates. If Applicable 
                    -----------------------------------------
Laws clearly exempts a purchase hereunder from a Tax, and if such Law also 
provides an exemption procedure, such as an exemption-certificate requirement, 
then, if the purchasing Party complies with such procedure, the providing Party 
shall not collect such Tax during the effective period of such exemption. Such 
exemption shall be effective upon receipt of the exemption certificate or 
affidavit in accordance with the terms set forth in subsection 29.6.6. If 
Applicable Laws clearly exempts a purchase hereunder from a Tax, but does not 
also provide an exemption procedure, then the providing Party shall not collect 
such Tax if the purchasing Party (i) furnishes the providing Party with a letter
signed by an officer requesting such an exemption and citing the provision in 
the Law which clearly allows such exemption and (ii) supplies the providing 
Party with an indemnification agreement, reasonably acceptable to the providing 
Party (e.g., an agreement commonly used in the industry), which holds the 
       - -
providing Party harmless on an after-tax basis with respect to its forbearing to
collect such Tax.

                                      57

<PAGE>
 
               29.6.6.  Notices for Purposes of this Subsection 29.6. All 
                        --------------------------------------------
notices, affidavits, exemption-certificates or other communications required or 
permitted to be given by either Party to the other, for purposes of this 
subsection 29.6. shall be made in writing and shall be delivered in person or 
sent by certified mail, return receipt requested, or registered mail, or a 
courier service providing proof of service, and sent to the addressees set forth
in subsection 29.10 as well as to the following:

          To Bell Atlantic:        Tax Administration
                                   Bell Atlantic Network Services, Inc.
                                   1717 Arch Street
                                   30/th/ Floor
                                   Philadelphia, PA 19103

          To MFS:                  Corporate Tax Department
                                   MFS Communications Company, Inc.
                                   11808 Miracle Hills Drive
                                   Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addressees
by giving notice is accordance with the terms of this subsection 29.6. Any
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT. Neither Party shall assign this Agreement nor any of its
rights or obligations hereunder without the prior written consent of the other 
Party, which consent shall not be unreasonably withheld. Any assignment or 
delegation in violation of this subsection 29.7 shall be void and ineffective 
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS

          29.8.1 Except may otherwise be provided in this Agreement, each Party
shall submit on a monthly basis an itemized statement of charges incurred by the
other Party during the preceding month(s) for services rendered hereunder.
Payment of billed amounts under this Agreement, whether billed on a monthly
basis or as otherwise provided herein, shall be due, in immediately available 
U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2 Although it is the intent of both Parties to submit timely and
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or
a waiver of the right to payment of the incurred charges, by the billing Party
under this Agreement, and the billed Party shall not be entitled to dispute the
billing Party statement(s) based on such Party's failure to submit them in a
timely fashion.

          29.8.3  If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60)days 
of its receipt of the invoice containing such

                                      58
<PAGE>
 
disputed amount give notice to the Billing Party of the amounts it disputes 
("Disputed Amounts") and include in such notice the specific details and reasons
for disputing each item. The Non-Paying Party shall pay when due (i) all 
undisputed amounts to the Billing Party and (ii) all Disputed Amounts into an 
interest bearing escrow account with a third party escrow agent mutually agreed 
upon by the Parties.

          29.8.4   If the Parties are unable to resolve the issues related to 
the Disputed Amounts in the normal course of business within ninety (90) days
after delivery to the Billing Party of notice of the Disputed Amounts, each of 
the Parties shall appoint a designated representative that has authority to 
settle the dispute and that is at a higher level of management than the persons 
with direct responsibility for administration of this Agreement. The designated 
representatives shall meet as often as they reasonably deem necessary in order 
to discuss the dispute and negotiate in good faith in an effort to resolve such 
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant 
information made by one Party to the other Party shall be honored.

          29.8.5   If the Parties are unable to resolve issues related to the 
Disputed Amounts within forty-five (45) days after the Parties' appointment of 
designated representatives pursuant to subsection 29.8.4, then either Party may 
file a complaint with the Commission to resolve such issues or proceed with any 
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus 
applicable late fees, to be paid to either Party.

          29.8.6   The Parties agree that all negotiations pursuant to this 
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state 
rules of evidence.

          29.8.7   Any undisputed amounts not paid when due shall accrue 
interest from the date such amounts were due at the lesser of (i) one and 
one-half percent (1-1/2%) per month or (ii) the highest rate of interest that 
may be charged under applicable law.

     29.9  DISPUTE RESOLUTION.  Any dispute between the Parties regarding the 
interpretation or enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial 
forum of competent jurisdiction.

     29.10 NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing and shall be (a) delivered personally, (b)
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by
telecopy to the following addresses of the Parties:

           To MFS:


<PAGE>
 
          MFS Intelenet of Virginia, Inc.
          33 Whitehall St.
          15/th/ Floor
          New York, NY 10004
          Attn: Director, Regulatory Affairs - Eastern Region
          Facsimile: 212/843-3060

          To Bell Atlantic:

          Director - Interconnection Services
          Bell Atlantic Network Services, Inc.
          1320 N. Courthouse Road
          9/th/ Floor
          Arlington, VA 22201
          Facsimile: 703/974-2183

          with a copy to:

          Vice President and General Counsel
          Bell Atlantic - Virginia, Inc.
          600 East Main Street
          24/th/ Floor
          Richmond, VA 23261
          Facsimile: (804) 772-2143

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual 
receipt, (ii) the next business day when notice is sent via express mail or 
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of telecopy.

     29.11  SECTION 252(I) OBLIGATIONS.

            29.11.1 If, at any time during the term of this Agreement, either
Party enters into an agreement to provide an intergrated package of services or
arrangements substantially similar to that described herein to another CLEC (in
the case of BA), or another incumbent LEC (in the case of MFS), operating within
the same state to which this Agreement applies, on terms significantly 
different than those available under this Agreement (the "Other Agreement"), 
then the other Party may opt to adopt, on a prospective basis only, the rates, 
terms, and conditions contained in the Other Agreement (i) in its entirety, or 
(ii) that relate directly to any of the following individual services, Network 
Elements, or arrangements, for its own reciprocal arrangements with the first 
Party, including, without limitation, any term or volume commitments or network 
architecture configurations:

                                      60











  
         
<PAGE>
 
          (a)  Unbundled Loop Elements - Section 251(c)(3) of the Act (Section
11 of this Agreement): or

          (b)  Collocation - Section 251(c)(6) of the Act (Section 13 of this 
Agreement): or

          (c)  Number Portability - Section 251(b)(2) of the Act (Section 14 of
this Agreement): or

          (d)  Access to Rights of Way - Section 251(b)(4) of the Act (Section
16 of this Agreement).

          (e)  transiting arrangements.

          29.11.2  To the extent the exercise of the foregoing options requires 
a rearrangement of facilities by the providing Party, the opting Party shall be 
liable for the non-recurring charges associated therewith.

          29.11.3  The Party electing to exercise such option shall do so by 
delivering written notice to the first Party. Upon receipt of said notice by the
first Party, the Parties shall amend this Agreement to provide the same rates, 
terms and conditions to the notifying Party for the remaining term of this 
Agreement; provided, however, that the Party exercising its option under this 
subsection 29.11 must continue to provide the same services or arrangements to 
the first Party as required by this Agreement, subject either to the rates, 
terms, and conditions applicable to the first Party in its agreement with the 
third party or to the rates, terms, and conditions of this Agreement, whichever 
is more favorable to the first Party in its sole determination.

          29.11.4  BA represents and warrants that, as of the date of this 
Agreement, it has not entered into any comparable Interconnection agreement with
any other CLEC in BA's service territory that is significantly more favorable 
than the terms contained herein.  BA makes no warranty or representation with 
respect to its Interconnection arrangements with its affiliates of ITCs.

     29.12 JOINT WORK PRODUCT. This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and
shall be fairly interpreted in accordance with its terms and, in the event of
any ambiguities, no inferences shall be drawn against either Party.

     29.13 NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. This Agreement is
for the sole benefit of the Parties and their permitted assigns, and nothing
herein express or implied shall create or be construed to create any third-party
beneficiary rights hereunder. Except for provisions herein expressly authorizing
a Party to act for another, nothing in this Agreement shall constitute a party
as a legal representative or agent of the other Party, nor shall a Party have
the right or authority to assume, create or incur any liability or any
obligation of any kind, express or implied, against or in the name or on behalf
of the other Party unless otherwise expressly

                                      61

<PAGE>
 
permitted by such other Party. Except as otherwise expressly provided in this 
Agreement, no Party undertakes to perform any obligation of the other Party, 
whether regulatory or contractual, or to assume any responsibility for the 
management of the other Party's business.

     29.14  NO LICENSE.
            
            29.14.1  Nothing in this Agreement shall be construed as the grant 
of a license, either express or implied, with respect to any patent, copyright, 
trademark, trade name, trade secret or any other proprietary or intellectual 
property now or hereafter owned, controlled or licensable by either Party. 
Neither Party may use any patent, copyrightable materials, trademark, trade 
name, trade secret or other intellectual property right of the other Party 
except in accordance with the terms of a separate license agreement between the 
Parties granting such rights.

            29.14.2  Neither Party shall have any obligation to defend, 
indemnify or hold harmless, or acquire any license or right for the benefit of, 
or owe any other obligation or have any liability to, the other Party or its 
customers based on or arising from any claim, demand, or proceeding by any third
party alleging or asserting that the use of any circuit, apparatus, or system, 
or the use of any software, or the performance of any service or method, or the 
provision of any facilities by either Party under this Agreement, alone or in 
combination with that of the other Party, constitutes direct, vicarious or 
contributory infringement or inducement to infringe, misuse or misappropriation
of any patent, copyright, trademark, trade secret, or any other proprietary or
intellectual property right of any Party or third party. Each Party, however,
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

            29.14.3  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, 
THE PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, 
ANY WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S 
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT 
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR 
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15  TECHNOLOGY UPGRADES.  Nothing in this Agreement shall limit BA's 
ability to upgrade its network through the incorporation of new equipment, new 
software or otherwise. BA shall provide MFS written notice at least ninety (90) 
days prior to the incorporation of any such upgrades in BA's network that will 
materially affect MFS's service. MFS shall be solely responsible for the cost 
and effort of accommodating such changes in its own network.

     29.16  SURVIVAL.  The Parties' obligations under this Agreement which by 
their nature are intended to continue beyond the termination or expiration of 
this Agreement shall survive the termination or expiration of this Agreement.

     29.17  ENTIRE AGREEMENT.  The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other documents or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with

                                      62
<PAGE>
 
respect to the subject matter hereof, superseding all prior understandings,
proposals and other communications, oral or written. Neither Party shall be
bound by any preprinted terms additional to or different from those in this
Agreement that may appear subsequently in the other Party's form documents,
purchase orders, quotations, acknowledgments, invoices or other communications.

     29.18.  COUNTERPARTS. This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19.  MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No modification, 
amendment, supplement to, or waiver of the Agreement or any of its provisions 
shall be effective and binding upon the Parties unless it is made in writing and
duly signed by the Parties. A failure or delay of either Party to enforce any of
the provisions hereof, to exercise any option which is herein provided, or to 
require performance of any of the provisions hereof shall in no way be construed
to be a waiver of such provisions or options.

     29.20.  SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and
inure to the benefit of the Parties and their respective legal successors and
permitted assigns.

     29.21.  PUBLICITY. Neither Party shall use the name of the other Party in 
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      63
<PAGE>
 
                                 SCHEDULE 12.3
                          SUPPORT SERVICES FOR RESALE
                          ---------------------------


1.   BA OSS SERVICES
     ---------------

     1.1  Definitions
          -----------
     
     As used in this Schedule 12.3, the following terms shall have the meanings 
     stated below:

     1.1.1  "BA Operations Support Systems" means BA systems for pre-ordering, 
     ordering, provisioning, maintenance and repair, and billing.

     1.1.2  "BA OSS Services" means access to BA Operations Support Systems
     functions. The term "BA OSS Services" includes, but is not limited to: (a)
     BA's provision of MFS Usage Information to MFS pursuant to Section 1.3
     below: and, (b) "BA OSS Information", as defined in Section 1.1.4 below.
     
     1.1.3  "BA OSS Facilities" means any gateways, interfaces, databases,
     facilities, equipment, software, or systems, used by BA to provide BA OSS
     Services to MFS.

     1.1.4  "BA OSS Information" means any information accessed by, or disclosed
     or provided to, MFS through or as a part of BA OSS Services. The term "BA
     OSS Information" includes, but is not limited to: (a) any Customer
     Information related to a BA Customer or an MFS Customer accessed by, or
     disclosed or provided to, MFS through or as a part of BA OSS Services: and,
     (b) any MFS Usage Information (as defined in Section 1.1.6 below) accessed
     by, or disclosed or provided to, MFS.

     1.1.5  "BA Retail Telecommunications Service" means any Telecommunications
     Service that Bell Atlantic provides at retail to subscribers that are not
     Telecommunications Carriers. The term "BA Retail Telecommunications
     Service" does not include any exchange access service (as defined in
     Section 3(16) of the Act. 47 U.S.C. (S) 153(16)) provided by BA.

     1.1.6  "MFS Usage Information" means the usage information for a BA Retail
     Telecommunications Service purchased by MFS under this Agreement that BA
     would record if BA was furnishing such BA Retail Telecommunications Service
     to a BA end-user retail Customer.
<PAGE>
 
     1.1.7  "Customer Information" means CPNI, as defined in the Act, of a
     Customer and any other non-public, individually identifiable information
     about a Customer or the purchase by a Customer of the services or products
     of a Party.

     1.2 BA OSS Services
         ---------------

     1.2.1  Upon request by MFS, BA shall provide to MFS, pursuant to Section 
     251(c)(3) of the Act, 47 U.S.C. (S) 251(c)(3), BA OSS Services.

     1.2.2  Subject to the requirements of Applicable Laws, BA Operations
     Support Systems, BA Operations Support Systems functions, BA OSS
     Facilities, BA OSS Information, and the BA OSS Services that will be
     offered by BA, shall be as determined by BA. Subject to the requirements of
     Applicable Laws, BA shall have the right to change BA Operations Support
     Systems, BA Operations Support Systems functions, BA OSS Facilities, BA OSS
     Information, and the BA OSS Services, from time-to-time, without the
     consent of MFS. Except as otherwise provided by this Agreement or
     Applicable Laws, BA will give MFS notice in writing or electronically
     (which may be by giving MFS access to a database or an Internet site that
     contains the applicable information, or by other electronic means) of
     material modification of the operation of BA OSS Services furnished under
     this Agreement at least sixty (60) days prior to the time the material
     modification becomes effective.

     1.3 MFS Usage Information
         ---------------------

     1.3.1  Upon request by MFS, BA shall provide to MFS, pursuant to Section   
     251(c)(3) of the Act, 47 U.S.C. (S) 251(c)(3), MFS Usage Information.

     1.3.2  MFS Usage Information will be available to MFS through the 
     following:
     
            (a) Daily Usage File on Data Tape.

            (b) Daily Usage File through Network Data Mover ("NDM").
          
            (c) Daily Usage File through Centralized Message Distribution System
     ("CMDS").

     1.3.3.1  MFS Usage Information will be provided in a Bellcore Exchange 
     Message Records ("EMR") format.

     1.3.3.2  Daily Usage File Data Tapes provided pursuant to Section 1.3.2(a) 
     above will be issued each day, Monday through Friday, except holidays
     observed by BA.
<PAGE>
 
     1.3.4   Except as stated in this Section 1.3, subject to the requirements 
     of Applicable Laws, the manner in which, and the frequency with which, MFS
     Usage Information will be provided to MFS shall be determined by BA.

     1.4     Access to and Use of BA OSS Facilities
             --------------------------------------

     1.4.1   BA OSS Facilities may be accessed and used by MFS only to the 
     extent necessary for MFS's access to and use of BA OSS Services pursuant to
     this Agreement.

     1.4.2   BA OSS Facilities may be accessed and used by MFS only to provide 
     Telecommunications Services to MFS Customers.

     1.4.3   MFS shall restrict access to and use of BA OSS Facilities to MFS. 
     This Schedule 12.3 does not grant to MFS any right or license to grant
     sublicenses to other persons, or permission to other persons (except MFS's
     employees, agents and contractors, in accordance with section 1.4.7
     below), to access or use BA OSS Facilities.

     1.4.4   MFS shall not (a) alter, modify or damage the BA OSS Facilities 
     (including, but not limited to, BA software), (b) copy, remove, derive,
     reverse engineer, or decompile, software from the BA OSS Facilities, or (c)
     obtain access through BA OSS Facilities to BA databases, facilities,
     equipment, software, or systems, which are not offered for MFS's use under
     this Schedule 12.3.

     1.4.5   MFS shall comply with all practices and procedures established by 
     BA for access to and use of BA OSS Facilities (including, but not limited
     to, BA practices and procedures with regard to security and use of access
     and user identification codes).

     1.4.6   All practices and procedures for access to and use of BA OSS 
     Facilities, and all access and user identification codes for BA OSS
     Facilities: (a) shall remain the property of BA; (b) shall be used by MFS
     only in connection with MFS's use of BA OSS Facilities permitted by this
     Schedule 12.3; and, (c) shall be treated by MFS as Proprietary Information
     of BA pursuant to subsection 29.4 of the Agreement.

     1.4.7   MFS's employees, agents and contractors may access and use BA OSS 
     Facilities only to the extent necessary for MFS's access to and use of the
     BA OSS Facilities permitted by this Agreement. Any access to or use of BA
     OSS Facilities by MFS's employees, agents, or contractors, shall be subject
     to the provisions of the Agreement, including, but not limited to,
     subsection 29.4 thereof and Sections 1.4.6 and 1.5.3.3 of this Schedule
     12.3.

     1.5     BA OSS Information
             ------------------

<PAGE>
 
     1.5.1     Subject to the provisions of this Agreement and Applicable Laws,
     BA grants to MFS a non-exclusive license to use BA OSS information.

     1.5.2     All BA OSS Information shall at all times remain the property of 
     BA. Except as expressly stated in this Schedule 12.3, MFS shall acquire no 
     rights in or to any BA OSS Information.

     1.5.3.1   The provisions of this Section 1.5.3 shall apply to all BA OSS 
     Information, except (a) MFS Usage Information, (b) CPNI of MFS, and (c)
     CPNI of a BA Customer or an MFS Customer, to the extent the Customer has
     authorized MFS to use the Customer Information.

     1.5.3.2   BA OSS Information may be accessed and used by MFS only to 
     provide Telecommunications Services to MFS Customers.

     1.5.3.3   MFS shall treat BA OSS Information that is designated by BA, 
     through written or electronic notice (including, but not limited to,
     through the BA OSS Services), as "Confidential" or "Proprietary" as
     Proprietary Information of BA pursuant to subsection 29.4 of the Agreement.

     1.5.3.4   Except as expressly stated in this Schedule 12.3, this Agreement 
     does not grant to MFS any right or license to grant sublicenses to other
     persons, or permission to other persons (except MFS's employees, agents or
     contractors, in accordance with Section 1.5.3.5 below), to access, use or
     disclose BA OSS Information.

     1.5.3.5   MFS's employees, agents and contractors may access, use and 
     disclose BA OSS Information only to the extent necessary for MFS's access
     to, and use and disclosure of, BA OSS Information permitted by this
     Schedule 12.3. Any access to, or use disclosure of, BA OSS Information by
     MFS's employees, agents or contractors, shall be subject to the provisions
     of this Agreement, including, but not limited to, subsection 29.4 of the
     Agreement and Section 1.5.3.3 above.

     1.5.3.6   MFS's license to use BA OSS Information shall expire upon the 
     earlier of: (a) termination of the license in accordance with this Schedule
     12.3; or (b) expiration or termination of the Agreement.

     1.5.3.7   All BA OSS Information received by MFS shall be destroyed or 
     returned by MFS to BA, upon expiration, suspension or termination of the
     license to use such BA OSS Information.

     1.5.4     Unless sooner terminated or suspended in accordance with the 
     Agreement or this Schedule 12.3 (including, but not limited to, subsection
     22.3 of the

<PAGE>
 
     Agreement and Section 1.6.1 below). MFS's access to BA OSS Information
     through BA OSS Services shall terminate upon the expiration or termination
     of the Agreement.

     1.5.5.1   BA shall have the right (but not the obligation) to perform at 
     BA's expense (provided that there will be no charge to BA for reasonable
     access to MFS' employees, books, records, documents and facilities) an
     audit of MFS upon three (3) full business days notice to MFS to ascertain
     whether MFS is complying with the requirements of Applicable Laws and this
     Agreement with regard to MFS's access to, and use and disclosure of, BA OSS
     Information.

     1.5.5.2   Without in any way limiting any other rights BA may have under 
     the Agreement or Applicable Laws, BA shall have the right but not the
     obligation) to monitor MFS's access to and use of BA OSS Information which
     is made available by BA to MFS pursuant to this Agreement, to ascertain
     whether MFS is complying with the requirements of Applicable Laws and this
     Agreement, with regard to MFS's access to, and use and disclosure of, such
     BA OSS Information. The foregoing right shall include, but not be limited
     to, the right (but not the obligation) to electronically monitor at BA's
     expense (provided that there will be no charge to BA by MFS to perform this
     activity). MFS's access to and use of BA OSS Information which is made
     available by BA to MFS through BA OSS Facilities.

     1.5.5.3   Information obtained by BA pursuant to this Section 1.5.5 shall 
     be treated by BA as Proprietary Information of MFS pursuant to subsection
     29.4 of the Agreement; provided that, BA shall have the right (but not the
     obligation) to use and disclose information obtained by BA pursuant to this
     Section 1.5.5 to enforce BA's rights under this Agreement or Applicable
     Laws.

     1.5.6     MFS acknowledges that the BA OSS Information, by its nature, is 
     updated and corrected on a continuous basis by BA, and therefore that BA
     OSS Information is subject to change from time to time.

     1.6  Liabilities and Remedies
          ------------------------

     1.6.1     Any breach by MFS, or MFS's employees, agents or contractors, of 
     the provisions of Sections 1.4 or 1.5 above shall be deemed a material
     breach of the Agreement. In addition, if MFS or an employee agent or
     contractor of MFS at any time breaches a provision of Sections 1.4 or 1.5
     above and such breach continues for more than fifteen (15) days after
     written notice thereof from BA, then, except as otherwise required by
     Applicable Laws, BA shall have the right, upon the notice to MFS, to
     suspend the license to use BA OSS Information granted by Section 1.5.1
     above and/or the provision of BA OSS Services, in whole or in part.


<PAGE>
 
     1.6.2   MFS agrees that BA would be irreparably injured by a breach of 
     Sections 1.4 or 1.5 above by MFS or the employees, agents or contractors of
     MFS, and that BA shall be entitled to seek equitable relief, including
     injunctive relief and specific performance, in the event of any such
     breach. Such remedies shall not be deemed to be the exclusive remedies for
     any such breach, but shall be in addition to any other remedies available
     under this Agreement or at law or in equity.

     1.7  Relation to Applicable Laws
          ---------------------------

     The provisions of Sections 1.4, 1.5 and 1.6 above shall be in addition to
     and not in derogation of any provisions of Applicable Laws, including, but
     not limited to, 47 U.S.C (S) 222, and are not intended to constitute a
     waiver by BA of any right with regard to protection of the confidentiality
     of the information of BA or BA Customers provided by Applicable Laws.

     1.8  Cooperation
          -----------

     MFS, at MFS's expense, shall reasonably cooperate with BA in using BA OSS
     Services. Such cooperation shall include, but not be limited to, the
     following:

     1.8.1   Upon request by BA, MFS shall by no later than the fifteenth (15th)
     day of the month preceding the first calendar month of each calendar
     quarter submit to BA reasonable, good faith estimates (by geographic area
     designated by BA) of the volume of each BA Retail Telecommunications
     Service for which MFS anticipates submitting orders in each week of the
     next calendar quarter.

     1.8.2   MFS shall participate in cooperative testing of BA OSS Services and
     shall provide assistance to BA in identifying and correcting mistakes,
     omissions, interruptions, delays, errors, defects, faults, failures, or
     other deficiencies, in BA OSS Services. The Parties will jointly agree upon
     the schedule for such testing and the tests that will be conducted.

     1.9  BA Access to Information Related to MFS Customers
          -------------------------------------------------

     BA shall have the right to access, use and disclose information related to
     MFS Customers that is in BA's possession (including, but not limited to, in
     BA OSS Facilities) to the extent such access, use and/or disclosure has
     been authorized by the MFS Customer in the manner required by Applicable
     Laws.

2    BELL ATLANTIC PRE-OSS SERVICES
     ------------------------------

     2.1  As used in this Schedule 12.3, "BA Pre-OSS Service" means a service 
     that allows the performance of an activity that is comparable to an
     activity to be performed through a BA OSS Service and that BA offers to
     provide to MFS. The term "BA Pre-OSS Service" includes, but is not limited
     to, the activity of placing

<PAGE>
 
     orders for BA Telecommunications Services through a telephone facsimile
     communication. Prior to purchasing BA OSS Services, MFS may purchase BA 
     Pre-OSS Services.

     2.2  Subject to the requirements of Applicable Laws, the BA Pre-OSS
     Services that will be offered by BA shall be as determined by BA and BA
     shall have the right to change BA Pre-OSS Services, from time-to-time,
     without the consent of MFS. Except as otherwise provided by this Agreement
     or Applicable Laws, BA will give MFS notice in writing or electronically
     (which may be by giving MFS access to a database or an Internet site that
     contains the applicable information, or by other electronic means) of
     material modification of the operation of BA Pre-OSS Services furnished
     under this Agreement at least thirty (30) days prior to the time the
     material modification becomes effective.

     2.3  Subject to the requirements of Applicable Laws, the prices for BA Pre-
     OSS Services shall be as determined by BA and shall be subject to change by
     BA from time-to-time.

     2.4  The provisions of Section 1.5 through 1.9 above shall also apply to BA
     Pre-OSS Services. For the purposes of this Section 2.4: (a) references in
     Sections 1.5 through 1.9 above to BA OSS Services shall be deemed to
     include BA Pre-OSS Services; and, (b) references in Sections 1.5 through
     1.9 above to BA OSS Information shall be deemed to include information made
     available to MFS through BA Pre-OSS Services.

3.   RATES AND CHARGES
     -----------------

     3.1  The prices for the foregoing services shall be as set forth in BA's
     Tariffs or, in the absence of an applicable BA Tariff price, in Exhibit A
     or, if not set forth in either, as may be determined by BA from time to
     time. If BA at any time offers a resale support service the prices for
     which are not stated in BA's Tariffs or Exhibit A and MFS elects to
     purchase such service. BA shall have the right to revise Exhibit A to add
     such prices; provided that, if the resale support service is already being
     used by MFS at the time BA revises Exhibit A to add such prices, except as
     otherwise required by this Agreement or Applicable Laws, the revision shall
     not become effective until BA has given MFS thirty (30) days prior notice
     of the revision.
<PAGE>
 
                                                                       EXHIBIT A

                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.

                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   ------------------------------------

A.   BA SERVICES, FACILITIES, AND ARRANGEMENTS:

<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------------
       BA SERVICE                                      NON-RECURRING             RECURRING
       ----------                                      -------------             ---------
- ----------------------------------------------------------------------------------------------------
 <S>                                                   <C>                       
 1.a.  Entrance facilities, and transport, as          Per interstate [BA FCC #1 sec. 6.9.1.] and 
       appropriate, for Interconnection at             (proposed) intrastate [BA-VA SCC 217 
       BA End Office, Tandem Office,                   sec. 6.8.2] access tariffs for Feature Group
       Serving Wire Center, or other Point             D service/2/
       of Interconnection

                                                       Illustrative:

                                                         Interstate non-recurring: $1, plus $1
                                                       switched access connection charge per 
                                                       trunk; DS-1 entrance facility $210-$212/mo.

                                                         Intrastate nonrecurring: $895 for first DS-
                                                       1, $280 for additional, plus $25 switched 
                                                       access connection charge per trunk; DS-1
                                                       entrance facility $270/mo.

- ----------------------------------------------------------------------------------------------------
 1.b.  Collocation and related services for            Per interstate [BA FCC 1 sec. 19] and
       Interconnection at BA End Office,               intrastate access tariffs/3/
       Tandem Office, or Serving Wire
       Center

- ----------------------------------------------------------------------------------------------------
</TABLE> 

________________________

/1/  Rates listed herein for services, facilities, or arrangements that are 
marked with an asterisk (*) are fixed pursuant to Section 20 of the Agreement 
for the initial term of the Agreement, as set forth in Section 22 of the 
Agreement.  Rates for services, facilities or arrangements that are not marked 
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.

/2/  Pending approval of the BA intrastate local transport restructure tariff 
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

/3/  Pending approval of the BA intrastate collocation tariff to be filed no 
later December 31, 1996, all collocation services shall be charged at rates 
found in BA FCC 1 sec.19.

                                       1
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------
       BA SERVICE                                      NON-RECURRING               RECURRING
       ----------                                      -------------               ---------
- ------------------------------------------------------------------------------------------------------------
<S>                                                    <C>                         <C> 
 1.c.  Tandem transit arrangements (for                Per tariffs cited in 
       Interconnection between MFS and                 sections 1.a. and           Per interstate [BA
       carriers other than BA)                         1.b. above, as              FCC 1 sec. 6.9.1.B]
                                                       applicable; separate        and (proposed)
                                                       trunks required for         intrastate [BA-VA
                                                       IXC subtending              SCC 217 sec.
                                                       trunks                      6.8.2.B] for tandem
                                                                                   switching and 
                                                                                   tandem switched 
                                                                                   transport, as
                                                                                   applicable/5/


                                                                                   Illustrative:        
                                                                                                        
                                                                                     Interstate,        
                                                                                   (proposed) intrastate
                                                                                   tandem switching     
                                                                                   $.000999/mou.        
                                                                                   tandem switched      
                                                                                   transport            
                                                                                   $.000195/mou plus    
                                                                                   $.000045/mou/mile     

- ------------------------------------------------------------------------------------------------------------ 
 1.d.  911 Interconnection                             Per tariffs citied in 1.a., 1.b., and 1.c. above,
                                                       as applicable, for entrance facility plus
                                                       applicable transport, or Collocation 
                                                       Arrangement at 911 tandem

- ------------------------------------------------------------------------------------------------------------ 
</TABLE> 

________________

/4/  See note 2 above.
/5/  See note 2 above.

                                       2
<PAGE>
 
<TABLE> 
<CAPTION> 
- --------------------------------------------------------------------------------------- 
     BA SERVICE                              NON-RECURRING        RECURRING
     ----------                              -------------        ---------
- --------------------------------------------------------------------------------------- 
<S>                                          <C>                  <C>     
1.e. Directory assistance Interconnection    Intrastate per       Intrastate per   
                                             (proposed) BA-VA     (proposed) BA-VA 
                                             SCC 217 sec. 9.6.B   SCC 217 sec. 9.6.B:
                                             (transport)/6/
                                                                  Illustrative:

                                                                    Per call rate
                                                                  $.000092 fixed,
                                                                  $.000021 per mile,
                                                                  $.000462 tandem
                                                                  switching, $.003705
                                                                  interconnection    

                                              Interstate per BA   Interstate per BA 
                                              FCC 1 sec. 9.6.B    FCC 1 sec. 9.6.B 

                                                                  Illustrative: 

                                                                    Per call rate
                                                                  $.000082 fixed,
                                                                  $.000019 per mile,
                                                                  $.000353 tandem
                                                                  switching, $002311
                                                                  interconnection     
- --------------------------------------------------------------------------------------- 
1.f. Operator services (call completion)      Per separate contract 
     Interconnection                          
- --------------------------------------------------------------------------------------- 
2.   Unbundled elements                       Available as listed herein and in 
                                              interstate and intrastate tariffs, and 
                                              pursuant to Section 11, of the Agreement
- --------------------------------------------------------------------------------------- 
3.   Poles, ducts, conduits, ROW              Per contract rates pursuant to 47 U.S.C.
                                              sec. 224

                                              Illustrative: 

                                                Duct (Northern Virginia) $4.50/ft/yr.

                                                Pole $4.46/attachment/yr.  
- --------------------------------------------------------------------------------------- 
</TABLE> 

________________________

 .    See note 2 above.
 .    See note 2 above.

                                       3
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------
       BA SERVICE                                      NON-RECURRING               RECURRING
       ----------                                      -------------               ---------
- ------------------------------------------------------------------------------------------------------------
<S>                                                    <C>                         <C> 
 4.a.  Local loop transmission*                        Permanent rates to          Permanent rates to
                                                       be determined by            be determined by 
        Unbundled Local Loop Element                   appropriate arbitral        appropriate arbitral
                                                       body. Interim rates         body. Interim rates
        Cross Connection to POTS loop                  will apply until the        will apply until the
                                                       permanent rates are         permanent rates are
                                                       determined./8/              determined./9/     

- ------------------------------------------------------------------------------------------------------------
 4.b.  Special construction charges                    As applicable per BA-VA SCC 203 sec. 2

- ------------------------------------------------------------------------------------------------------------ 
 4.c.  Central office technician charges               Per interstate [BA FCC 1 sec. 13.2 or sec.
       (during normal working hours)                   19.5] tariff.

- ------------------------------------------------------------------------------------------------------------ 
 5.a.  Trunk Side local transport
                                                       Per interstate [BA FCC 1 sec. 6.9.1.C] and
        DS-1 transport                                 (proposed) intrastate [BA-VA SCC 217 
                                                       sec. 6.8.2.C] tariffs

                                                       Illustrative recurring:

                                                         Interstate $60/mo. fixed, $17.70/mile/mo.

                                                         Intrastate $75 mo. fixed, $30/mile/mo.
- ------------------------------------------------------------------------------------------------------------ 
 5.b.  DS-3 transport                                  Tariff reference see 5.a. above.


                                                       Illustrative recurring:

                                                         Interstate, intrastate $900/mo.fixed,
                                                       $180/mile/mo.

- ------------------------------------------------------------------------------------------------------------ 
</TABLE> 


___________________

/8/  Interim rates will be based on the following order of precedence of 
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in 
the state, (iii) any Commission recommendation, or (iv) mutual agreement of the 
Parties.

/9/  See preceding note.

/10/ See note 2 above.

                                       4
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------
       BA SERVICE                                      NON-RECURRING               RECURRING
       ----------                                      -------------               ---------
- ------------------------------------------------------------------------------------------------------------
<S>                                                    <C>                         <C> 
 6.    Local switching*

        POTS switch Port                               $6 service order            $1.50/mo., plus
                                                       plus $6/Port                usage per tariff,
                                                                                   minus wholesale
                                                                                   discount per section
                                                                                   14 below            
- ------------------------------------------------------------------------------------------------------------
 7.a.  Operator services

        911 service (data entry; database              No charge
       maintenance)*
- ------------------------------------------------------------------------------------------------------------
 7.b.  Directory assistance                            Per tariff or separate      Per tariff or separate
                                                       contract; branding          contract
                                                       available
                                                                                   Illustrative tariff
                                                                                   rates:

                                                                                   Interstate [BA FCC
                                                                                   1 sec. 9.6], $.275-
                                                                                   .288 per call

                                                                                   Intrastate (proposed)
                                                                                   [BA-VA SCC 217
                                                                                   sec. 9.6.A], $.25 per
                                                                                   call

                                                                                   Directory transport
                                                                                   per section 1.e.
                                                                                   above

- ------------------------------------------------------------------------------------------------------------
 7.c.  Operator call completion                        Per separate contract; branding available
- ------------------------------------------------------------------------------------------------------------   
 8.a.  White pages directory listings*                 $5.00 per primary           No charge
                                                       listing per number
- ------------------------------------------------------------------------------------------------------------   
 8.b.    Books & delivery (annual home                 No charge for normal numbers of books
       area directories only)*                         delivered to end users; bulk deliveries to 
                                                       CLEC per separate arrangement
- ------------------------------------------------------------------------------------------------------------   
</TABLE> 

                                       5
<PAGE>
 
<TABLE> 
<CAPTION> 
- ---------------------------------------------------------------------------------------------
       BA SERVICE                              NON-RECURRING            RECURRING
       ----------                              -------------            ---------
- ---------------------------------------------------------------------------------------------
 <S>                                           <C>                      <C> 
 8.c.    Additional listings, changes to       Per tariff [BA-VA        Per tariff [BA-VA
       listing, non-listed, non-published      SCC 203 sec. 4]          SCC 203 sec.4]
       and other extra services.
                                               Illustrative:            Illustrative:
                                                
                                                Additional listing:     Additional listing:
                                               $9 residence: $17        $1.12/mo. residence,
                                               business                 $1.42/mo. business


                                                Change to listing:      Non-list:
                                               $9 residence: $17        $1.06/mo. residence
                                               business                 or business


                                                Non-list:    
                                               $9 residence: $17        Non-published:
                                               business                 $1.71/mo. residence
                                                                        or business

                                                Non-published:
                                               $9 residence: $17
                                               business
- ---------------------------------------------------------------------------------------------
 9.    Access to telephone numbers (NXX
       codes issued per ICCF Code              No charge
       Administration Guidelines)*

- ---------------------------------------------------------------------------------------------
 10.a  SS7 Interconnection                     Per interstate [BA       Per interstate [BA
                                               FCC 1 sec. 6.9.1.G]      FCC 1 sec. 6.9.1.L]
                                               and intrastate [BA-      and intrastate [BA-
                                               VA SCC 217 sec.          VA SCC 217 sec.
                                               6.8.2.C] tariff          6.8.2.G] tariff


                                                                        Illustrative:

                                                                          STP ports,
                                                                        $900/mo.,
                                      
                                                                          STP access,
                                                                        $3.50/mile/mo. to
                                                                        $5.72/mile/mo.
- ---------------------------------------------------------------------------------------------
</TABLE> 

                                       6
<PAGE>
 
- --------------------------------------------------------------------------------
       BA SERVICE             NON-RECURRING            RECURRING
       ----------             -------------            --------- 
- --------------------------------------------------------------------------------
10.    LIDB Interconnection   Per tariff [BA FCC       Per tariff [BA FCC
b                             1 sec. 6.9.1.M]          1 sec. 6.9.1M]

                              Illustrative:            Illustrative:

                               Originating point        Query validation
                              code, $125               $.04/query

                                                        Query transport
                                                       $.0002/query

- --------------------------------------------------------------------------------
10.c   800/888 data base      No separate charge       Per interstate [BA
       Interconnection        (included in FGD         FCC 1 sec.
                              trunk and STP            6.9.2.A.1]. and
                              links)                   intrastate [BA-VA
                                                       SCC 217 sec.
                                                       6.8.2.K] tariffs


                                                       Illustrative:

                                                        Interstate basic
                                                       query, $.003105/query;
                                                       vertical feature package,
                                                       $.000337/query

                                                        Intrastate basic query,
                                                       $.003089/query; vertical
                                                       feature package, 
                                                       $.000327/query

- --------------------------------------------------------------------------------
11.a   Interim number port-   service order per        $3/mo. per number for up
       ability through co-    location $30             to 10 paths; $.40/mo.per
       carrier call for-                               additional path
       warding 
                              installation per
                              number $35 (unless
                              installed with 
                              unbundled loop)

                              installation per
                              separate path
                              arrangement $20
- --------------------------------------------------------------------------------

                                       7

<PAGE>
 
- ------------------------------------------------------------------------------ 
     BA SERVICE                              NON-RECURRING   RECURRING
     ----------                              -------------   ---------
- -------------------------------------------------------------------------------
11.   Access pass-through to number                          In accordance with
b    portability purchaser*                                  section 14.5 of
                                                             Agreement.
- -------------------------------------------------------------------------------
12.  Local dialing parity*                   No charge
- -------------------------------------------------------------------------------
13.a Reciprocal call termination

      Local Traffic delivered to Bell
     Atlantic Interconnection Point

      First year*                                            $.009/mou
     --------------------------------------------------------------------------
      After first year*                                      In accordance with
                                                             note 14 below
- -------------------------------------------------------------------------------
13.   Access charges for termination of                      Per interstate and
b    intrastate and interstate Toll Traffic                  intrastate access
                                                             tariffs (charged in
                                                             conjunction with
                                                             Local Traffic,
                                                             using PLU and PIU, 
                                                             as appropriate)
- --------------------------------------------------------------------------------
14.a Wholesale rates for resale of           Percentage discount from retail 
                                             -------------------------------
     telecommunications services             tariff/12/
                                             ----------
     provided to end users/11/                              
- --------------------------------------------------------------------------------
14.  Resale of retail Telecommunications     21.3% or discount as determined by
b    Services if MFS provides its own        further Commission order.
     Operator Services
- --------------------------------------------------------------------------------
14.c Resale of retail Telecommunications     18.5% or discount as determined by
     Services if MFS uses BA Operator        further Commission order.
     Services
- --------------------------------------------------------------------------------
___________________________

/11/ Excludes telecommunications services designated primarily for wholesale, 
such as switched and special access, and, subject to Section 12 of the 
Agreement, the following additional arrangements that are not subject to resale:
limited duration (90 days or less) promotional offerings, public coin telephone 
services, and technical and market trials. Taxes shall be collected and remitted
by the reseller and BA in accordance with legal requirements and as agreed 
between the Parties. Surcharges (e.g., 911, telecommunications relay service, 
universal service fund) shall be collected by the reseller and either remitted 
to the recipient agency or NECA, or passed through to BA for remittance to the 
recipient agency or NECA, as appropriate and agreed between the Parties. End 
user common line charges shall be collected by the reseller and remitted to BA.

/12/ Pending establishment of mechanized billing procedures adapted to resale, 
the Parties will agree upon a composite "bottom-of-the-bill" discount that 
reflects the discounts and exclusions identified herein, and such other 
adjustments as the Parties agree.

                                       8

<PAGE>
 
<TABLE> 
<CAPTION>  
- ----------------------------------------------------------------------------------------------------------------------
          BA SERVICE                                   NON-RECURRING                           RECURRING
          ----------                                   -------------                           ---------
- ----------------------------------------------------------------------------------------------------------------------
<S>                                                    <C>                                    <C> 
15.      Access to BA OSS/13/ 
- ----------------------------------------------------------------------------------------------------------------------
15.a     Access to Pre-Ordering OSS                                                           $.26/Query
- ----------------------------------------------------------------------------------------------------------------------
15.b     Access to Ordering OSS                                                              $4.53/Transaction
- ----------------------------------------------------------------------------------------------------------------------
15.c     Access to Provisioning OSS                                                           Included in Ordering
- ----------------------------------------------------------------------------------------------------------------------
15d      Access to Maintenance and Repair                                                     $1.23/Trouble Ticket
         OSS
- ----------------------------------------------------------------------------------------------------------------------
15.e.1   Access to Billing OSS; CD-ROM                                                        $261.04/CD-ROM
- ----------------------------------------------------------------------------------------------------------------------
15.e.2   Access to Billing OSS; Daily Usage
         File
            Existing Message Recording                                                        $.000274/Message
- ----------------------------------------------------------------------------------------------------------------------
15.e.3   Access to Billing OSS; Daily Usage
         File Delivery
             Data Tape                                $64.96/Programming Hour                 $20.11/Tape
                                                      
             Network Data Mover                       Not Applicable                          $.000099/Message

             CMDS                                     $64.96/Programming Hour                 $.000099/Message
                                                      
- ----------------------------------------------------------------------------------------------------------------------
15.e.4   Access to Billing OSS; Daily Usage
         File Transport
           9.6 kb Communications Port                 $8,335.27/Port                          $10.84/Month
- ----------------------------------------------------------------------------------------------------------------------
</TABLE> 

______________________________

/13/      The rates for BA OSS Services that appear in Section 15 above shall
apply until the earlier of August 15, 1997 or the date the Commission approves
rates for BA OSS Services. If the Commission approves rates for BA OSS Services
on or before August 15, 1997, the rates approved by the Commission will apply
from the date they are approved by the Commission until any subsequent change in
rates becomes effective in accordance with this Agreement.

          If by August 15, 1997 the commission has not approved rates for BA OSS
Services ,from August 16, 1997 until such time as the Commission approves rates
for BA OSS Services. BA will track the usage of BA OSS Services by MFS. When the
Commission approves rates for BA OSS Services, those rates will apply from
August 16, 1997 until any subsequent change in rates becomes effective in
accordance with this Agreement.

          MFS reserves the right to at any time prior to the above-mentioned
Commission approval of rates for BA OSS Services initiate or participate in a
proceeding before the Commission or other governmental entity of appropriate
jurisdiction to obtain a determination as to the lawfulness of the rates stated
above in Section 15 for Bell Atlantic OSS Services. However, until such time as
the Commission or other governmental entity of appropriate jurisdiction, in an
order that is binding upon Bell Atlantic, requires Bell Atlantic to change or
delete the rates stated above in Section 15 for Bell Atlantic OSS Services. MFS 
agrees to pay such rates as provided in this Footnote.

          When rates for BA OSS Services are approved by the Commission. Section
15 above shall be amended by the Parties to state such rates.

                                       9

<PAGE>
 
- --------------------------------------------------------------------------------
       BA SERVICE                     NON-RECURRING               RECURRING
       ----------                     -------------               ---------
- --------------------------------------------------------------------------------
         56 kb Communications Port    $34,494.62/Port             $29.93/Month
- --------------------------------------------------------------------------------
         256 kb Communications Port   $57,422.87/Port             $29.93/Month
- --------------------------------------------------------------------------------
         T1 Communications Port       $204,901.39/Port            $380.18/Month
- --------------------------------------------------------------------------------
         Line Installation            $64.96/Programming          Not Applicable
                                      Hour/Port
- --------------------------------------------------------------------------------
         Port Set-up                  $10.43/Port                 Not Applicable
- --------------------------------------------------------------------------------
         Network Control              $64.96/Programming          Not Applicable
         Programming Coding           Hour/Port         
- --------------------------------------------------------------------------------

                                      10
<PAGE>
 
<TABLE> 
<CAPTION> 
       MFS SERVICES, FACILITIES, AND ARRANGEMENTS:
- ----------------------------------------------------------------------------------------------- 
       MFS SERVICE                           NON-RECURRING              RECURRING
       -----------                           -------------              ---------
- ----------------------------------------------------------------------------------------------- 
<S>                                          <C>                        <C> 
1.a.   Interim Number Portability        
       through co-carrier call           
       forwarding*                       
                                         
         Number portability*                 $30/service order.         $3/mo. for ten paths
                                             $35/number (not            per number; plus
                                             ordered with ULL)          $.40/mo. per
                                                                        additional path
                                             $20 per additional
                                             path order
- ----------------------------------------------------------------------------------------------- 
1.b      Access pass-through to number                                  In accordance with   
       portability purchaser*                                           sec. 14.5 of
                                                                        Agreement
- ----------------------------------------------------------------------------------------------- 
2.     Local dialing parity*                 No change
- ----------------------------------------------------------------------------------------------- 
3.a    Reciprocal call termination       

         Local Traffic delivered to MFS  
       Interconnection Point*            

         First year*                                                    $.009/mou
       ----------------------------------------------------------------------------------------
         After first year*                                              In accordance with 
                                                                        note 14 below
- -----------------------------------------------------------------------------------------------  
3.b      Access charges for termination                                 Per MFS interstate
       of intrastate and interstate Toll                                and intrastate access
       Traffic                                                          rates (charged in
                                                                        conjunction with
                                                                        Local Traffic, using
                                                                        PLU and PIU, as
                                                                        appropriate)
- -----------------------------------------------------------------------------------------------  
4.     All other MFS services available      Available at MFS tariffed or otherwise
       to BA for purposes of                 generally available rates, not to exceed BA
       effectuating local exchange           rates for equivalent services available to MFS
       competition                       
- ----------------------------------------------------------------------------------------------- 
5.       Other Services                  
       Information Service billing fee       No Charge                  $.03 per call
- ----------------------------------------------------------------------------------------------- 
</TABLE> 

                                      11

<PAGE>
 
14   LOCAL TRAFFIC TERMINATION RATES (AFTER FIRST YEAR)

A.   Charges by BA
     -------------
     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA 
          Access Tandem: $.009 per mou.

     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou
     Note:  All BA-IPs identified in Schedule 4.0 as of the Effective Date are 
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs
     shall be subject to rate of $.009 per mou.

B.   Charges by MFS
     --------------
1.   Single-tiered interconnection structure:
     MFS's rates for the termination of BA's Local Traffic under the 
     single-tiered interconnection structure shall be recalculated once each 
     year on each anniversary of the Effective Date (the "Real Determination 
     Date"). The initial Rate Determination Date shall be the first anniversary 
     of the Effective Date. The methodology for recalculating the rates are as
     follows:
          LSWC/Access Tandem Minutes = Total minutes of use of Local Traffic
          delivered by MFS to the BA LSWC or BA Access Tandem for most recent
          billed month.
          End Office Minutes = Total minutes of use Local Traffic delivered by 
          MFS directly to the terminating BA End Office for most recent billed 
          month.
          Total Minutes = Total minutes of use of Local Traffic delivered by MFS
          to BA for most recent billed month.
          MFS Charge at the M-IP =
          (LSWC/Access Tandem Minutes x $.009) + (End Office Minutes x $.007)
          -------------------------------------------------------------------
                                 Total Minutes

2.   Multiple-tiered interconnection structure (if offered by MFS to any 
     carrier)
     (a) Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009
     (b) Local Traffic delivered to terminating MFS End Office/node: $.007

C.   Miscellaneous Notes
     -------------------
1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended, 
and/or (ii) where the Tandem Office that it subtends is not located within 25 
miles of the Tandem Office that is subtended by the terminating End Office, then
such Party shall (x) in addition to paying the LSWC/Access Tandem termination 
rate described above, purchase the necessary facilities from the terminating 
Party to transport such Traffic to a qualifying LSWC or Access Tandem that is 
not subject to either conditions (i) or (ii) above, (y) purchase such other 
service(s) as the terminating Party may offer under applicable tariff to remedy 
such condition(s), or (z) enter into a new compensation arrangement as the 
Parties may agree. Notwithstanding the foregoing, nothing in this Agreement 
shall obligate BA to provide switching services at a LSWC when it functions as 
such.

                                      12



<PAGE>
 
2.   In the event the two-tiered rate structure described above is modified
pursuant to Applicable Law to a single rate structure. BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting
Local Traffic it receives at its LSWC to the first point of switching in its
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure
set forth above is intended by the Parties to be a Local Traffic termination
rate for Interconnection to the M-IP within each LATA that is reciprocal and
equal to the actual rates that will be charged by BA to MFS under the two-tiered
Local Traffic termination rate structure described above that will apply after
the first anniversary of the Effective Date. The single MFS termination rate is
also intended to provide financial incentives to MFS to deliver traffic directly
to BA's terminating End Offices once MFS's traffic volumes reach an appropriate
threshold. The Parties agree that the Reciprocal Compensation rate(s) set forth
herein recover a reasonable approximation of each Party's additional costs of
terminating calls that originate on the network facilities of the other Party.

                                      13
<PAGE>
 

                                  APPENDIX 2


<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA

     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
the listed Dates.

<TABLE> 
<CAPTION> 
- --------------------------------------------------------------------------------------------------------------------
LATA IN VIRGINIA         MILESTONE                                                                   DATE
- --------------------------------------------------------------------------------------------------------------------
<S>                      <C>                                                                         <C> 
LATA 236                 LATA Start Date ("SD)                                                       7/21/98                  
                         ------------------------------------------------------------------------------------------- 
                         SS7 Certification, Collocation, and NXX(s)                                  8/19/98   
                         Applied For 
                         -------------------------------------------------------------------------------------------              
                         Parties Agree on Initial Network Design                                     8/24/98
                         -------------------------------------------------------------------------------------------
                         Valid Access Service Request(s) ("ASRs") and                                TBD 
                         Routing Information Received by BA
                         -------------------------------------------------------------------------------------------
                         Collocation Arrangements Complete for Trunk                                 N/A
                         Interconnection and IDLC for ULLs
                         -------------------------------------------------------------------------------------------
                         All Trunks Tested and Turned Up; SS7 Certification Achieved; /1/            11/20/98     
                         VG ULL Capability Available
                         -------------------------------------------------------------------------------------------
                         Call-through Testing Completed;                                             12/11/98
                         "Interconnection Activation Date"
- --------------------------------------------------------------------------------------------------------------------
</TABLE> 

     Failure of a Party or the Parties to meet an earlier Milestone Date shall 
not relieve either Party of the responsibility to make its best efforts to meet 
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that, 
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when 
Focal has an effective Tariff for business Telephone Exchange Service in the 
Commonwealth of Virginia and has a significant number of Telephone Exchange 
Service Customer lines in service for business Telephone Exchange Service 
Customers in that LATA in the Commonwealth of Virginia that are not affiliates 
or employees of either BA or Focal, and (ii) residential Telephone Exchange 
Service shall be considered "fully operational" in a LATA in the Commonwealth of
Virginia when Focal has an effective Tariff for residential Telephone Exchange 
Service in the Commonwealth of Virginia and has a significant number of 
Telephone Exchange Service Customer lines in service for residential Telephone 
Exchange Service Customers in that LATA in the Commonwealth of Virginia that are
not affiliates or employees of either BA or Focal.



_________________________________

/1/ SS7 certification scheduling depends on actual schedule availability at time
of request.


                                       1
<PAGE>
 
SCHEDULE 4.0


VIRGINIA - INTERCONNECTION POINTS IN LATA


                                   LATA 236
                                   --------


F-IP:     Washington D.C. Switch
          1120 Vermont Ave. N.W.
          Washington, D.C.
          WASHDCRKDS2

BA-IP     WorldCom COLO
          1025 N. Irving Street
          Arlington, VA
          ARTNVAARHVA



<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                          Dated as of October 2, 1998


                                by and between


                        BELL ATLANTIC - MARYLAND, INC.

                                      and

                       FOCAL COMMUNICATIONS CORPORATION
                              OF THE MID-ATLANTIC
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996


     This Interconnection Agreement (this "Agreement"), under Sections 251 and
252 of the Telecommunications Act of 1996 (the "Act"), is effective as of the
2nd day of October, 1998 (the "Effective Date"), by and between Bell Atlantic -
Maryland, Inc. ("BA"), a Maryland corporation with offices at 1 East Pratt
Street, Baltimore, Maryland 21202, and Focal Communications Corporation of the
Mid - Atlantic ("Focal"), a Delaware corporation with offices at 200 N. LaSalle
Street, Suite 800, Chicago, Illinois 60601 (each a "Party" and, collectively,
the "Parties").

     WHEREAS, Focal has requested that BA make available to Focal
Interconnection, service and unbundled Network Elements upon the same terms and
conditions as provided in the Interconnection Agreement (and amendments thereto)
between MFS Intelenet of Maryland, Inc. and BA, dated as of July 16, 1996
(revised as of July 29, 1997), for the State of Maryland, approved by the
Commission under Section 252 of the Act (the "Separate Agreement") and attached
as Appendix 1 hereto; and

     WHEREAS, BA has undertaken to make such terms and conditions available to
Focal hereby only because and, to the extent required by, Section 252(i) of the
Act.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Focal and BA hereby agree as follows:

     1.0  INCORPORATION OF APPENDICES BY REFERENCE

     1.1  Except as expressly stated herein, the terms and conditions of the
Separate Agreement (as set forth in Appendix 1 hereto), as it is in effect on
the date hereof after giving effect to operation of law, and of the other
Appendices hereto are incorporated by reference in their entirety herein and
form an integral part of this Agreement.

     1.2  References in Appendix 1 hereto to MFS Intelenet of Maryland, Inc. or
to MFS shall for purposes of this Agreement be deemed to refer to Focal.

     1.3  References in Appendix 1 hereto to the "Effective Date", the date of
effectiveness thereof and like provisions shall for purposes of this Agreement
be deemed to refer to the date first written above. Unless terminated earlier in
accordance with the terms of Appendix 1 hereto, this Agreement shall continue in
effect until the Separate Agreement expires or is otherwise terminated.
<PAGE>
 
     1.4  The Joint Grooming Plan referred to in Section 10.1 of Appendix 1
hereto shall be developed upon the request of either Party within a reasonable
amount of time after receipt of such request.

     1.5  Notwithstanding Section 27.5 of Appendix 1 hereto, at such time as BA
makes available the Performance Monitoring Reports set forth in the Memorandum
Opinion and Order adopted by the FCC on August 14, 1997 (the "FCC Merger Order")
to other Telecommunications Carriers purchasing Interconnection from BA, BA
shall provide Focal with the Performance Monitoring Reports applicable to Focal
in accordance with the requirements of said FCC Merger Order.

     1.6  All notices, affidavits, exemption-certificates or other
communications to Focal under Section 29.6.6 of Appendix 1 hereto shall be sent
to the following address:

          Focal Communications Corporation of the Mid - Atlantic
          Attn:  Corporate Tax Department
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone:  (312) 895-8400

     1.7  All notices, affidavits, exemption-certificates or other
communications to BA under Section 29.6.6 of Appendix 1 hereto shall be sent to
the following address:

          Tax Administration
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          Room 3109
          New York, New York 10036

     1.8  Notices to Focal under Section 29.10 of Appendix 1 hereto shall be
sent to the following address:

          Focal Communications Corporation of the Mid - Atlantic
          Attn:  Senior Manager - Carrier Relations
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone:  (312) 895-8400

     1.9  Notices to BA under Section 29.10 of Appendix 1 hereto shall be sent
to the following address:

                                       2
<PAGE>
 
          President - Telecom Industry Services
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          40/th/ Floor
          New York, New York 10036
          Facsimile: (212) 597-2585

          with a copy to:

          Bell Atlantic Network Services, Inc.
          Attn: Mr. Jack H. White,
          Associate General Counsel
          1320 N. Court House Road, 8/th/ Floor
          Arlington, Virginia 22201
          Facsimile: (703) 974-O744

          with a copy to:

          Vice President and General Counsel
          Bell Atlantic - Maryland, Inc.
          1 East Pratt Street
          8th Floor
          Baltimore, Maryland 21202
          Facsimile: (410) 393-4078

     1.10 Schedules 3.0 and 4.0 set forth at Appendix 2 hereto shall replace and
supersede in their entirety Schedules 3.0 and 4.0 of Appendix 1 hereto.

     2.0  CLARIFICATIONS

     2.1  The entry into, filing and performance by BA of this Agreement does
not in any way constitute a waiver by BA of any of the rights and remedies it
may have to seek review of any of the provisions of the Separate Agreement, or
to petition the Commission, other administrative body or court for
reconsideration or reversal of any determination made by any of them, or to seek
review in any way of any portion of this Agreement in connection with Focal's
election under Section 252(i) of the Act.

                                       3
<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be 
executed as of this 2nd day of October, 1998.



FOCAL COMMUNICATIONS                    BELL ATLANTIC-
 CORPORATION OF                          MARYLAND, INC.
 THE MID - ATLANTIC



By: /s/ John R. Barnicle                By: /s/ Jeffrey A. Masoner
    --------------------------             -----------------------------------

Printed: JOHN R. BARNICLE               Printed: Jeffrey A. Masoner
         ---------------------                  ------------------------------

Title: E.V.P. - C.O.O.                  Title: Vice-President - Interconnection 
       -----------------------                 --------------------------------
                                               Services Policy & Planning
                                               -------------------------- 
      
                                       4
<PAGE>
 




                                   APPENDIX 1
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                           DATED AS OF JULY 16, 1996


                                BY AND BETWEEN


                         BELL ATLANTIC-VIRGINIA, INC.

                                      AND

                        MFS INTELENET OF VIRGINIA, INC.
<PAGE>
 

                               TABLE OF CONTENTS
                               -----------------
<TABLE> 
<CAPTION>                                                                   PAGE
                                                                            ----
<S>                                                                         <C> 
1.0   DEFINITIONS                                                             2

2.0   INTERPRETATION AND CONSTRUCTION                                        10 

3.0   INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION 
      SCHEDULE                                                               11 

4.0   INTERCONNECTION PURSUANT TO SECTION TO SECTION 251(c)(2)               11
4.1   Scope                                                                  12
4.2   Physical Architecture                                                  13 
4.3   Initial Architecture                                                   13
4.4   Interconnection in Additional LATAs                                    14
4.5   Interconnection Points for Different Types of Traffic                  15

5.0   TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE 
      TRAFFIC PURSUANT TO SECTION 251(c)(2)                                  15
5.1   Scope of Traffic                                                       15
5.2   Trunk Group Connections and Ordering                                   15
5.3   Additional Switching System Hierarchy and Trunking Requirements        15
5.4   Signaling                                                              16
5.5   Grades of Service                                                      16
5.6   Measurement and Billing                                                16
5.7   Reciprocal Compensation Arrangements -- Section 251(b)(5)              17

6.0   TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC 
      PURSUANT TO 251(c)(2)                                                  18
6.1   Scope of Traffic                                                       18
6.2   Trunk Group Architecture and Traffic Routing                           18
6.3   Meet-Point Billing Arrangements                                        19
6.4   800/888 Traffic                                                        21 

7.0   TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC                    22
7.1   Information Services Traffic                                           22
7.2   LSV/VCI Traffic                                                        23
7.3   Transit Service                                                        24
7.4   911/E911 Arrangements                                                  25
7.5   Ancillary Traffic Generally                                            26

8.0   NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS                      26 
</TABLE> 

                                       i
<PAGE>
 
9.0   NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES                        26

9.3   Interference or Impairment                                         28
9.4   Repeated or Willful Noncompliance                                  28
9.5   Outage Repair Standard                                             28
9.6   Notice of Changes -- Section 251(c)(5)                             28

10.0  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND
      INSTALLATION, MAINTENANCE, TESTING AND REPAIR                      28
10.1  Joint Network Reconfiguration and Grooming Plan                    28
10.2  Installation, Maintenance, Testing and Repair                      29
10.3  Forecasting Requirements for Trunk Provisioning                    29

11.0  UNBUNDLED ACCESS -- SECTION 251(c)(3)                              30
11.1  Unbundled Local Loop (ULL) Transmission Types                      30
11.2  Port Types                                                         31
11.3  Trunk Side Local Transport                                         32
11.4  Limitations on Unbundled Access                                    32
11.5  Availability of Other Network Elements on an Unbundled Basis       33
11.6  Provisioning of Unbundled Local Loops                              33
11.7  Maintenance of Unbundled Local Loops                               35
11.8  Rates and Charges                                                  35

12.0  RESALE -- SECTIONS 251(c)(4)and 251(b)(1)                          35
12.1  Availability of Retail Rates for Resale                            35
12.2  Availability of Wholesale Rates for Resale                         35

13.0  COLLOCATION -- SECTION 251(c)(6)                                   36

14.0  NUMBER PORTABILITY -- SECTION 251(b)(2)                            37
14.1  Scope                                                              37
14.2  Procedures for Providing INP Through Remote Call Forwarding        38     
14.3  Procedures for Providing INP Through Direct Inward Dial Trunks
      (Flex-DID)                                                         39
14.4  Procedures for Providing LTNP Through Full NXX Code Migration      39
14.5  Receipt of Terminating Compensation on Traffic to INP'ed Numbers   39
14.6  Recovery of INP Costs Pursuant to FCC Order and Rulemaking         40


15.0  DIALING PARITY -- SECTION 251(b)(3)                                41

16.0  ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                       41

17.0  DATABASES AND SIGNALING                                            41

                                     ii   
<PAGE>
 
18.0  COORDINATED SERVICE ARRANGEMENTS                                42
18.1  Intercept and Referral Announcements                            42
18.2  Coordinated Repair Calls                                        43
18.3  Customer Authorization                                          43
                                                              
19.0  DIRECTORY SERVICES ARRANGEMENTS                                 43
19.1  Directory Listings and Directory Distributions                  44
19.2  Yellow Page Maintenance                                         45
19.3  Service Information Pages                                       45
19.4  Directory Assistance (DA); Call Completion                      46
                                                              
20.0  COORDINATION WITH TARIFF TERMS                                  45
                                                              
21.0  INSURANCE                                                       46
                                                              
22.0  TERM AND TERMINATION                                            47
                                                              
23.0  DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                    48
                                                              
24.0  CANCELLATION CHARGES                                            48
                                                              
25.0  INDEMNIFICATION                                                 48
                                                              
26.0  LIMITATION OF LIABILITY                                         49
                                                              
27.0  PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                  50
27.1  Certain Definitions                                             50
27.2  Performance Standards                                           51
27.3  Limitations                                                     51
27.4  Service Quality Standards                                       52
27.5  Records                                                         52
                                                              
28.0  COMPLIANCE WITH LAWS; REGULATORY APPROVAL                       52
                                                              
29.0  MISCELLANEOUS                                                   53
29.1  Authorization                                                   53
29.2  Independent Contractor                                          53
29.3  Force Majeure                                                   53
29.4  Confidentiality                                                 54
29.5  Choice of Law                                                   55
29.6  Taxes                                                           55
29.7  Assignment                                                      57
29.8  Billing and Payment; Disputed Amounts                           57
29.9  Dispute Resolution                                              58
29.10 Notices                                                         59

                                      iii
<PAGE>
 



29.11 Section 252(i) Obligations                                       59
29.12 Joint Work Product                                               60
29.13 No Third Party Beneficiaries; Disclaimer of Agency               61 
29.14 No License                                                       61
29.15 Technology Upgrades                                              61
29.16 Survival                                                         62
29.17 Entire Agreement                                                 62 
29.18 Counterparts                                                     62
29.19 Modification, Amendment, Supplement or Waiver                    62
29.20 Successors and Assigns                                           62   
29.21 Publicity                                                        62

                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------ 
                 
Schedules
- ---------

Schedule 1.0        Certain Terms As Defined in the Act, As of July 16, 1996
Schedule 3.0        Implementation Schedule
Schedule 4.0        Interconnection Points in LATA
Schedule 4.2        Physical Architecture Diagram
Schedule 4.3        Initial Architecture Diagram
Schedule 4.5        Interconnection Points for Different Types of Traffic
Schedule 6.3        Rate Elements Under Meet Point Billing
Schedule 27.0       Performance Interval Dates for Specified Activities
Schedule 27.1       MFS Service Quality Standards

Exhibits      
- --------

Exhibit A           Detailed Schedule of Itemized Charges
Exhibit B           Network Element Bona Fide Request
Exhibit C           Directory Assistance and Call Completion Services Agreement


                               iv               
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996


     This Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996, is effective as of the 16th day of July, 1996
(the "Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched
Exchange Access Services, and other Telecommunications Services (all as defined
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will interconnect their networks and provide other services as
required by the Act (as defined below) and additional services as set forth
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996
have specific requirements for interconnection, unbundling, and service resale,
commonly referred to as the "Checklist", and the Parties intend that this
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA
and MFS (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements,
ancillary services, and wholesale Telecommunications Services available for
resale within each LATA in which they both operate within Virginia. As such,
this Agreement is an integrated package that reflects a balancing of interests
critical to the Parties. It will be submitted to the Virginia State Corporation
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of
the Agreement. So long as the Agreement remains in effect, neither Party shall
advocate before any legislative, regulatory, or other public forum that any term
of this Agreement be modified or eliminated, unless otherwise mutually agreed by
the Parties.

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1.0  DEFINITIONS.

     As used in this Agreement, the following terms shall have the meanings
specified below in this Section 1.0. For convenience of reference only, the
definitions of certain terms that are As Defined in the Act (as defined below)
are set forth on Schedule 1.0.

     1.1  "Act" means the Communications Act of 1934 (47 U.S.C. 151 et. seq.) as
                                                                    --  ---
amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission.

     1.2  "ADSL" or "Asymmetrical Digital Subscriber Line" means a transmission
technology which transmits an asymmetrical digital signal of up to 6 mbps to the
Customer and up to 640 kbps from the Customer.

     1.3  [Reserved]

     1.4  "Agreement" means this Interconnection Agreement under Sections 251
and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5  "Ancillary Traffic," means all traffic that is destined for ancillary
services, or that may have special billing requirements, including but not
limited to the following: LSV/VCI, Directory Assistance, 911/E911, Operator
Services (call completion), 800/888 database query, LIDB, and information
services requiring special billing.

     1.6  "As Defined in the Act" means as specifically defined by the Act and
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     1.7  "As Described in the Act" means as described in or required by the Act
and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.8  "Automatic Number Identification" or "ANI" means a Feature Group D
signaling parameter which refers to the number transmitted through a network
identifying the billing number of the calling party.

     1.9  "Calling Party Number" or "CPN" is a Common Channel Signaling ("CCS")
parameter which refers to the number transmitted through a network identifying
the calling party.

     1.10 "Central Office Switch" means a switch used to provide
Telecommunications Services, including, but not limited to:

          (a) "End Office Switch" or "End Office" which is used to terminate
Customer station Loops for the purpose of interconnection to each other and to
trunks; and

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          (b) "Tandem Switch" or "Tandem Office" which is a switching entity
that is used to connect and switch trunk circuits between and among End Office
Switches and between and among End Office Switches and carriers' aggregation
points, points of termination, or points of presence. An "Access Tandem Office"
or "Access Tandem" is a Tandem Office with billing and recording capabilities
that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End
Office/Tandem Office Switch.

     1.11 [Reserved]

     1.12 "CLASS Features" means certain CCS-based features available to
Customers including, but not limited to: Automatic Call Back; Call Trace; Caller
Identification, and future offerings.

     1.13 "Collocation" means an arrangement whereby one Party's (the
"Collocating Party") facilities are terminated in equipment necessary for
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a
second Party (the "Housing Party"). For purposes of Collocation, the "premises"
of a Housing Party is limited to a Housing Party Wire Center, other mutually
agreed-upon locations of the Housing Party, or any other location for which
Collocation has been ordered by the FCC or Commission. Collocation may be
"physical" or "virtual". In "Physical Collocation," the Collocating Party
installs and maintains its own equipment in the Housing Party's premises. In
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA
currently provides Collocation under terms, rates, and conditions as described
in tariffs on file or soon to be filed with the FCC and the Commission. Upon
request by either Party, BA and MFS will address the provision of additional
types of Collocation arrangements, including additional physical locations and
alternative utilizations of space and facilities.

     1.14 "Commission" means the Virginia State Corporation Commission.

     1.15 "Common Channel Signaling" or "CCS" means a method of transmitting
call set-up and network control data over a digital signaling network separate
from the public switched telephone network facilities that carry the actual
voice or data traffic of the call. "SS7" means the common channel out of band
signaling protocol developed by the Consultative Committee for International
Telephone and Telegraph ("CCITT") and the American National Standards Institute
("ANSI"). BA and MFS currently utilize this out-of-band signaling protocol.
"CCSAS" or "CCSAS" means the common channel signaling access connection or
service, respectively, which connects one Party's signaling point of
interconnection ("SPOI") to the other Party's STP for the exchange of SS7
messages.

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     1.16  "Competing Local Exchange Carrier" or "CLEC" means any Local Exchange
Carrier other than BA, operating as such in BA's certificated territory in
Virginia. MFS is or will shortly become a CLEC.

     1.17  "Cross Connection" means a jumper cable or similar connection
provided pursuant to Collocation at the digital signal cross connect, Main
Distribution Frame or other suitable frame or panel between (i) the Collocating
Party's equipment and (ii) the equipment or facilities of the Housing Party.

     1.18  "Customer" means a third-party residence or business subscriber to
Telecommunications Services provided by either of the Parties.

     1.19  "Dialing Parity" is As Defined in the Act.

     1.20  "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.21  "Digital Signal Level 0" or "DS0" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.

     1.22  "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level
signal in the time-division multiplex hierarchy. In the time-division
multiplexing hierarchy of the telephone network, DS1 is the initial level of
multiplexing.

     1.23  "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level
in the time-division multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS3 is defined as the third level of
multiplexing.

     1.24  "Exchange Access" is As Defined in the Act.

     1.25. "Exchange Message Record" or "EMR" means the standard used for
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is
contained in BR-010-200-010 CRIS Exchange Message Record, a Bell Communications
Research, Inc. ("Bellcore") document that defines industry standards for
Exchange Message Records.

     1.26  [Reserved]

     1.27  "FCC" means the Federal Communications Commission.

     1.28  "HDSL" or "High-Bit Rate Digital Subscriber Line" means a
transmission technology which transmits up to 784 kbps simultaneously in both
directions on a two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line
code.

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     1.29  "Independent Telephone Company" or "ITC" means any entity other than
BA which, with respect to its operations within Virginia, is an "Incumbent Local
Exchange Carrier" As Described in the Act.

     1.30  "Information Service Traffic" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which is
addressed to an information service provided over a Party's information services
platform.

     1.31  "Integrated Digital Loop Carrier" means a subscriber loop carrier
system which integrates within the switch at a DSI level that is twenty-four
(24) loop transmission paths combined into a 1.544 Mbps digital signal.

     1.32. "Integrated Services Digital Network" or "ISDN" means a switched
network service providing end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN") provides
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B+D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for
digital transmission of twenty three (23) 64 kbps bearer channels and one 16
kbps data and signaling channel (23 B+D).

     1.33  "Interconnection" is as Described in the Act, and means the
connection of separate pieces of equipment or transmission facilities within,
between, or among networks. The architecture of Interconnection may include, but
is not limited to, Collocation Arrangements, entrance facilities, and Mid-Span
Meet arrangements.

     1.34  "Interexchange Carrier" or "IXC" means a carrier that provides,
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35  "Interim Number Portability" or "INP" means the use of existing and
available call routing, forwarding, and addressing capabilities (e.g. remote
call forwarding) to enable a Customer to receive Telephone Exchange Service
provided by any Local Exchange Carrier operating within the exchange area with
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of
whether the Customer's chosen Local Exchange Carrier is the carrier that
originally assigned the number to the Customer.

     1.36  "InterLATA" is As Defined in the Act.

     1.37  "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.38  "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.

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     1.39. "Line Status Verification" or "LSV" means an operator request for a
status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40  "Local Access and Transport Area" or "LATA" is As Defined in the Act.

     1.41  "Local Exchange Carrier" or "LEC" is As Defined in the Act. The
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42. "Local Serving Wire Center" means a Wire Center that (i) serves the
area in which the other Party's or a third party's Wire Center, aggregation
point, point of termination, or point of presence is located, or any Wire Center
in the LATA in which the other Party's Wire Center, aggregation point, point of
termination or point of presence is located in which the other Party has
established a Collocation Arrangement or is purchasing an entrance facility, and
(ii) has the necessary multiplexing capabilities for providing transport
services.

     1.43  "Local Telephone Number Portability" or "LTNP" means "number
portability" As Defined in the Act.

     1.44  "Local Traffic," means traffic that is originated by a Customer of
one Party on that Party's network and terminates to a Customer of the other
Party on that other Party's network, within a given local calling area, or
expanded area service ("EAS") area, as defined in BA's effective Customer
tariffs. Local Traffic does not include traffic originated or terminated by a
commercial mobile radio service carrier.

     1.45. "Main Distribution Frame" or "MDF" means the primary point at which
outside plant facilities terminate within a Wire Center, for interconnection to
other telecommunications facilities within the Wire Center.

     1.46. "MECAB" means the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
("OBF"), which functions under the auspices of the Carrier Liaison Committee
("CLC") of the Alliance for Telecommunications Industry Solutions ("ATIS"). The
MECAB document, published by Bellcore as Special Report SR-BDS-000983, contains
the recommended guidelines for the billing of an Exchange Access service
provided by two or more LECs, or by one LEC in two or more states, within a
single LATA.

     1.47  "MECOD" means the Multiple Exchange Carriers Ordering and Design
(MECOD) Guidelines for Access Services - Industry Support Interface, a document
developed by the Ordering/Provisioning Committee under the auspices of OBF. The
MECOD document, published by Bellcore as Special Report SR-STS-002643,
establishes methods for processing orders for Exchange Access service which is
to be provided by two or more LECs.

     1.48  "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched
Exchange Access Service to one

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of the LECs' End Office Switches, with each LEC receiving an appropriate share
of the transport element revenues as defined by their effective Exchange Access
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an
effective Meet-Point Billing arrangement.

     1.49. "Mid-Span Meet" means an Interconnection architecture whereby two
carriers' fiber transmission facilities meet at a mutually agreed-upon
Interconnection point.

     1.50  "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff"
means the MPB method whereby each LEC prepares and renders its own meet point
bill in accordance with its own Tariff(s) for the portion of the jointly-
provided Switched Exchange Access Service which the LEC provides.

     1.51  "Network Element" is As Defined in the Act.

     1.52  "Network Element Bona Fide Request" means the process described on
Exhibit B that prescribes the terms and conditions relating to a Party's request
that the other Party provide a Network Element not otherwise provided by the
terms of this Agreement.

     1.53  "North American Numbering Plan" or "NANP" means the numbering plan
used in the United States that also serves Canada, Bermuda, Puerto Rico and
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 3-
digit NXX code and 4-digit line number.

     1.54. "Numbering Plan Area" or "NPA" is also sometimes referred to as an
area code. There are two general categories of NPAs, "Geographic NPAs" and "Non-
Geographic NPAs." A Geographic NPA is associated with a defined geographic
area, and all telephone numbers bearing such NPA are associated with services
provided within that geographic area. A Non-Geographic NPA, also known as a
"Service Access Code" or "SAC Code," is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55  "NXX," "NXX Code," or "End Office Code" means the three digit switch
entity indicator (i.e. the first three digits of a seven digit telephone
number).

     1.56  "Permanent Number Portability" or "PNP" means the use of a database
or other technical solution that comports with regulations issued by the FCC to
provide LTNP for all customers and service providers.

     1.57  "Port Element" or "Port" means a line card (or equivalent) and
associated peripheral equipment on an End Office Switch which serves as the
Interconnection between individual loops or individual Customer trunks and the
switching components of an End Office Switch and the associated switching
functionality in that End Office Switch. Each Port is typically associated with
one (or more) telephone number(s) which serves as the Customer's network 
address.

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     1.58  "Rate Center Area" or "Exchange Area" means the specific geographic
point and corresponding geographic area which has been identified by a given LEC
as being associated with a particular NPA-NXX code assigned to the LEC for its
provision of Telephone Exchange Services. The Rate Center Area is the exclusive
geographic area which the LEC has identified as the area within which it will
provide Telephone Exchange Services bearing the particular NPA-NXX designation
associated with the specific Rate Center Area. A "Rate Center Point" is a
specific geographic point, defined by a V&H coordinate, located within the Rate
Center Area and used to measure distance for the purpose of billing Customers
for distance-sensitive Telephone Exchange Services and Toll Traffic.

     1.59  "Rate Demarcation Point" means the point of minimum penetration at
the Customer's premises or other point, as defined in a Party's Tariffs, where
network access recurring charges and LEC responsibility ends and beyond which
Customer responsibility begins.

     1.60  "Rating Point" or "Routing Point" means a specific geographic point
identified by a specific V&H coordinate. The Rating Point is used to route
inbound traffic to specified NPA-NXXs and to calculate mileage measurements for
distance-sensitive transport charges of switched access services. Pursuant to
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office
location, or a "LEC Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point/Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point corresponding to each unique and separate Rate Center.

     1.61  "Reciprocal Compensation" is As Described in the Act, and refers to
the payment arrangements that recover costs incurred for the transport and
termination of Local Traffic originating on one Party's network and terminating
on the other Party's network.

     1.62  "Service Control Point" or "SCP" means the node in the common channel
signaling network to which informational requests for service handling, such as
routing, are directed and processed. The SCP is a real time database system
that, based on a query from a service switching point and via a Signaling
Transfer Point, performs subscriber or application-specific service logic, and
then sends instructions back to the SSP on how to continue call processing.

     1.63  "Signaling Transfer Point" or "STP" means a specialized switch that
provides SS7 network access and performs SS7 message routing and screening.

     1.64  "Switched Access Detail Usage Data" means a category 1101XX record
as defined in the EMR Bellcore Practice BR-010-200-010.

     1.65  "Switched Access Summary Usage Data" means all category 1150XX as
defined in the EMR Bellcore Practice BR-0l0-200-0l0.

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     1.66  "Switched Exchange Access Service" means the offering of transmission
and switching services for the purpose of the origination or termination of Toll
Traffic. Switched Exchange Access Services include but may not be limited to:
Feature Group A, Feature Group B, Feature Group D, 700 access, 800 access, 888
access, and 900 access.

     1.67  "Synchronous Optical Network" or "SONET" means an optical interface
standard that allows inter-networking of transmission products from multiple
vendors. The base rate is 51.84 Mbps (OC-l/STS-l) and higher rates are direct
multiples of the base rate, up to 13.22 Gpbs.

     1.68  "Tariff" means any applicable federal or state tariff of a Party, or
standard agreement or other document that sets forth the generally available
terms and conditions under which a Party offers a particular service, facility,
or arrangement.

     1.69  "Technically Feasible Point" is As Described in the Act.

     1.70  "Telecommunications" is As Defined in the Act.

     1.71  "Telecommunications Act" means the Telecommunications Act of 1996 and
any rules and regulations promulgated thereunder.

     1.72  "Telecommunications Carrier" is As Defined in the Act.

     1.73  "Telecommunications Service" is As Defined in the Act.

     1.74  "Telephone Exchange Service," sometimes also referred to as "Exchange
Service," is As Defined in the Act. Telephone Exchange Service generally
provides the Customer with a telephonic connection to, and a unique telephone
number address on, the public switched telecommunications network, and enables
such Customer to place or receive calls to all other stations on the public
switched telecommunications network.

     1.75. "Toll Traffic" means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that Party's network and is not Local Traffic or Ancillary Traffic. Toll Traffic
may be either "IntraLATA Toll Traffic" or "InterLATA Toll Traffic," depending on
whether the originating and terminating points are within the same LATA.

     1.76  "Transit Traffic" means any traffic that originates from or
terminates at MFS's network, "transits" BA's network substantially unchanged,
and terminates to or originates from a third carrier's network, as the case may
be. "Transit Traffic Service" provides MFS with the ability to use its
connection to a BA Access Tandem Switch for the delivery of calls which
originate or terminate with MFS and terminate to or originate from a carrier
other than BA, such as another CLEC, a LEC other than BA, or a wireless carrier.
In these cases, neither the originating nor terminating Customer is a Customer
of BA. This service is provided through BA's Access Tandem

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Switches. "Transit Traffic" and "Transit Traffic Service" do not include or
apply to traffic that is subject to an effective Meet-Point Billing arrangement.

     1.77  "Trunk Side" means a Central Office Switch connection that is capable
of, and has been programmed to treat the circuit as, connecting to another
switching entity (e.g. another carrier's network). Trunk Side connections offer
those transmission and signaling features appropriate for the connection of
switching entities.

     1.78  "Unbundled Local Loop Element" or "ULL" means a transmission path
that extends from a Main Distribution Frame, DSX-panel, or functionally
comparable piece of equipment in the Customer's serving End Office to the Rate
Demarcation Point (or network interface device (NID) if installed) in or at a
Customer's premises. The actual loop transmission facilities used to provide an
ULL may utilize any of several technologies.

     1.79  "Verification with Call Interruption" or "VCI" means a service that
may be requested and provided when Line Status Verification has determined that
a line is busy due to an ongoing call. VCI is an operator interruption of that
ongoing call to inform the called party that a calling party is seeking to
complete his or her call to the called party.

     1.80  "Voice Grade" means either an analog signal of 300 to 3000 Hz or a
digital signal of 56/64 kilobits per second. When referring to digital voice
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.81  "Wire Center" means a building or portion thereof in which a Party
has the exclusive right of occupancy and which serves as a Routing Point for
Switched Exchange Access Service.

2.0  INTERPRETATION AND CONSTRUCTION.

     2.1   All references to Sections, Exhibits and Schedules shall be deemed to
be references to Sections of, and Exhibits and Schedules to, this Agreement
unless the context shall otherwise require. The headings used in this Agreement
are inserted for convenience of reference only and are not intended to be a part
of or to affect the meaning of this Agreement. Unless the context shall
otherwise require, any reference to any agreement, other instrument (including
BA or other third party offerings, guides or practices), statute, regulation,
rule or tariff is to such agreement, instrument, statute, regulation, or rule or
tariff as amended and supplemented from time to time (and, in the case of a
statute, regulation, rule or tariff, to any successor provision).

     2.2   Subject to the terms set forth in Section 20, each Party hereby
incorporates by reference those provisions of its tariffs that govern the
provision of any of the services or facilities provided hereunder. If any
provision of this Agreement and an applicable tariff cannot be reasonably
construed or interpreted to avoid conflict, the Parties agree to negotiate in
good faith to reconcile and resolve such conflict. If any provision contained in
this main body of the Agreement and any Exhibit hereto cannot be reasonably
construed or interpreted to avoid conflict, the

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provision contained in this main body of the Agreement shall prevail. The fact
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for
finding, a conflict for purposes of this Section 2.


3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1  Subject to the terms and conditions of this Agreement, each Party
shall exercise its best efforts to adhere to the Interconnection Activation
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to
provide fully operational service predominantly over its own Telephone Exchange
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes
of this Agreement, MFS's service in Virginia shall be considered provided
"predominantly over its own Telephone Exchange Service facilities" if MFS uses
its own Central Office Switch(es) (as opposed to resale of another carrier's
Telephone Exchange Service or Ports) to serve the majority of its Telephone
Exchange Service Customers, its own interoffice transport facilities for the
majority of its interoffice transport needs, and its own local loops (or
functional equivalent), in addition to resale of other carriers' Telephone
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2  Schedule 3.0 may be revised and supplemented from time to time upon
the mutual agreement of the Parties to reflect the intention of the Parties to
interconnect in additional LATAs pursuant to subsection 4.4 by attaching one or
more supplementary schedules to Schedule 3.0. The Parties stipulate and agree
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act, and the requirements of
the Competitive Checklist, under Section 271 of the Act. MFS represents that it
is, or intends to become, a provider of Telephone Exchange Service to
residential and business subscribers offered exclusively over its own Telephone
Exchange Service facilities or predominantly over its own Telephone Exchange
Service facilities in combination with the resale of the Telecommunications
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit
Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to the terms
and conditions of this Agreement, Interconnection of the Parties facilities and
equipment for the transmission and routing of Local Traffic and Toll Traffic
pursuant to this Section 4 shall be established on or before the corresponding
"Interconnection Activation Date" shown for each such LATA within Virginia on
Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and supplemented
from time to time upon the mutual agreement of the Parties to reflect
Interconnection in additional LATAs

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in Virginia pursuant to subsection 4.4 by attaching one or more supplementary   
addenda to such Schedules.
 
     4.1  SCOPE

          4.1.1  Section 4 describes the architecture for Interconnection of the
Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct trunk groups:

          Traffic Exchange Trunks for the transmission and routing of
          -----------------------
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251 (c)(2) of the Act, in accordance with Section 5 below;

          Access Toll Connecting Trunks for the transmission and routing of
          -----------------------------                                    
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Access Service via
          a BA Access Tandem, pursuant to Section 251 (c)(2) of the Act, in
          accordance with Section 6 below;

          Information Services Trunks for the transmission and routing of
          ---------------------------                                    
          terminating Information Services Traffic in accordance with Section 7
          below;

          LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
          --------------                                                        
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating E911/
          ---------------
          911 traffic, in accordance with Section 7 below;

          Directory Assistance Trunks for the transmission and routing of
          ---------------------------                                    
          terminating directory assistance traffic, in accordance with
          subsection 19.4 below; and

          Operator services (call completion) Trunks for the transmission and
          ------------------------------------------                         
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2  The SONET interconnection arrangement described in subsection
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA
Toll Traffic until such time as the Parties have agreed to appropriate
compensation arrangements relating to the exchange of other types of traffic
over such system, and (ii) subject to the Parties' reaching agreement on an
appropriate compensation arrangement in the event either Party will be providing
or utilizing (in terms of minutes of use) significantly more than one-half of
the SONET facility. Unless otherwise agreed to by the Parties, the SONET system
described herein shall not be used to exchange InterLATA Toll Traffic. Until the
SONET system has been established by the Parties in accordance with subsection
4.3 and this subsection 4.1.2, the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
(IntraLATA and InterLATA) Traffic.

                                      12
<PAGE>
 
          4.1.3  To the extent required by Section 251 of the Act, the Parties
represent that the arrangements provided in subsections 4.2 and 4.3 of this
Agreement provide for Interconnection to each other's networks at any
technically feasible point. For the purposes of this Agreement, the Parties
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a Local
Serving Wire Center and/or other points as specified herein, and, in the case of
MFS, at a node or Central Office and/or other points as specified herein
(collectively, the "Interconnection Points" or "IPs").

          4.1.4  The Parties shall establish physical interconnection points at
the available IPs at the locations designated in Schedule 4.0. The mutually
agreed-upon IPs on the MFS network at which MFS will provide transport and
termination of traffic shall be designated as the MFS Interconnection Points
("M-IPs"); the mutually agreed-upon IPs on the BA network shall be designated as
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of
charging for the transport of traffic from the BA-IP to the M-IP in any given
LATA, the M-IP shall be no further than an entrance facility away from the BA-IP
in such LATA. The Parties may by mutual agreement establish additional
interconnection points at any technically feasible points consistent with the
Act.

     4.2  PHYSICAL ARCHITECTURE. In each LATA identified on Schedule 4.0, MFS
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous
Optical Network ("SONET") transmission system by which they shall interconnect
their networks pursuant to the joint network reconfiguration and grooming plan
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the
following specifications:

          4,2.1  The SONET system shall be used to deliver appropriate traffic
to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2  The SONET transmission system in each LATA shall be configured
substantially as illustrated in Schedule 4.2 and pursuant to the Joint Grooming
Plan, or as otherwise mutually agreed. The Parties shall agree upon which Party
or Parties shall be responsible for procuring, installing, and maintaining the
agreed-upon Optical Line Terminating Multiplexor ("OLTM") equipment, fiber optic
facilities and other equipment pursuant to the Joint Grooming Plan, as
illustrated in that Schedule.

          4.2.3  The physical interface of MFS's and BA's facilities necessary
to effect SONET transmission shall be at the optical level via a Mid-Span Meet
or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1  The Parties agree to provide initial interconnection
arrangements utilizing electrical handoffs, substantially as illustrated in
Schedule 4.3, for a period of no more than

                                      13
<PAGE>
 
eighteen (18) months after the later of the Effective Date and the LATA Start
Date set forth for the LATA in Schedule 3.0; provided, however, that such
initial interconnection arrangements shall continue until (i) facilities
suitable for the SONET arrangements described in subsection 4.2 are established
by each of the Parties in its own sole discretion in the LATA at the mutually
agreed-upon SONET meet points and made available, and (ii) the Parties have
agreed upon fully compatible OLTM equipment for use with such facilities.

          4.3.2  The Parties agree to utilize the M-IP and BA-IP in each LATA as
designated in Schedule 4.0 as the points from which each Party will provide the
transport and termination of traffic.

          4.3.3  MFS shall provide its own facilities for the delivery of
traffic to a collocation arrangement established at the BA-IP pursuant to
Section 13. Bell Atlantic shall provide transport and termination of the traffic
beyond the BA-IP.

          4.3.4  BA shall purchase an MFS entrance facility (and any necessary
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the M-
IP. Alternatively, BA may choose to provide its own facilities to a collocation
arrangement established at the M-IP pursuant to Section 13. MFS shall provide
transport and termination of the traffic beyond the M-IP.

          4.3.5  Under this initial architecture described in this subsection
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5
below and pursuant to the other Party's Switched Exchange Access Service
tariffs. The other Party's Switched Exchange Access Service rates shall apply to
such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.

     4.4  INTERCONNECTION IN ADDITIONAL LATAS

          4.4.1  If MFS determines to offer Telephone Exchange Services in any
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange
Services, MFS shall provide written notice to BA of the need to establish
Interconnection in such LATA pursuant to this Agreement.

          4.4.2  The notice provided in subsection 4.4.1 shall include (i) the
initial Routing Point MFS has designated in the new LATA; (ii) MFS's requested
Interconnection Activation Date (and related milestone dates in accordance with
the format in Schedule 3.0); and (iii) a non-binding forecast of MFS's trunking
requirements.

          4.4.3  Unless otherwise agreed to by the Parties, the Parties shall
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local
Serving Wire Center that houses an Access Tandem Office within the LATA nearest
to the M-IP (as measured in airline miles

                                      14
<PAGE>
 
utilizing the V&H coordinates method) as the BA-IP in that LATA, provided that,
for the purpose of charging for the transport of traffic from the BA-IP to the 
M-IP, the M-IP shall be no further than an entrance facility away from the BA-
IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to
reflect the schedule applicable to each new LATA requested by MFS; provided,
however, that unless agreed by the Parties, the Interconnection Activation Date
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten
(10) business days of BA's receipt of MFS's notice, BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party
shall make available Interconnection Points and facilities for routing of
traffic from those Interconnection Points as designated in Schedule 4.5. Any
additional traffic that is not covered in Schedule 4.5 shall be subject to
separate negotiations between the Parties, except that (i) either Party may
deliver traffic of any type or character to the other Party for termination as
long as the delivering Party pays the receiving Party's then current Switched
Exchange Access rates for such traffic, and (ii) upon a bona fide request from
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an
agreement covering the exchange of such traffic.

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO
SECTION 251(c)(2)

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups
(the "Traffic Exchange Trunks") to be effected over the Interconnections
specified in Section 4.0 for the transmission and routing of Local Traffic and
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-l level or higher
for exchange of Local and Toll Traffic. Higher speed connections shall be made,
when and where available, in accordance with the Joint Grooming Plan prescribed
in Section 10. Ancillary Traffic trunk groups may be made below a DS-l level, as
may be agreed to by the Parties.

          5.2.2  Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

       5.3.1  For purposes of routing MFS traffic to BA, the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own or

                                      15
<PAGE>
 
other carriers' traffic. For purposes of routing BA traffic to MFS, the
subtending arrangements between MFS Access Tandem Switches (or functional
equivalent) and MFS End Office Switches (or functional equivalent) shall be the
same as the Access Tandem/End Office subtending arrangements (or functional
equivalent) which MFS maintains for the routing of its own or other carriers'
traffic.

     5.4     SIGNALING

     Each Party will provide the other Party with access to its databases and
associated signaling necessary for the routing and completion of the other
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5     GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6     MEASUREMENT AND BILLING

         5.6.1   For billing purposes, each Party shall pass Calling Party
Number ("CPN") information on each call carried over the Traffic Exchange
Trunks, wherever technically feasible. At such time as either Party has the
ability, as the Party receiving the traffic, to use such CPN information to
classify on an automated basis traffic delivered by the other Party as either
Local Traffic or Toll Traffic, such receiving Party shall bill the originating
Party the Local Traffic termination rates, Intrastate Exchange Access rates, or
Interstate Exchange Access rates applicable to each minute of Traffic for which
CPN is passed, as provided in Exhibit A and applicable Tariffs.

         5.6.2   If, under the circumstances set forth in subsection 5.6.1. it
is not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party the
Local Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, for which CPN is passed. For the remaining up
to ten percent (10%) of calls without CPN information, the receiving Parry shall
bill the originating Party for such traffic as Local Traffic termination rates,
Intrastate Exchange Access rates, or Interstate Exchange Access rates applicable
to each minute of traffic, as provided in Exhibit A and applicable Tariffs, in
direct proportion to the minutes of use of calls passed with CPN information.

         5.6.3   If it is not technically feasible for the originating Party to
pass CPN on more than ten percent (10%) of calls, or if the receiving Party
lacks the ability to use CPN information to classify on an automated basis
traffic delivered by the other Parts as either Local Traffic or Toll Traffic,
and the originating Party chooses to combine Local and Toll Traffic on the same
trunk group, it will supply an auditable Percent Local Use ("PLU") report
quarterly, based on the previous three months' traffic, and applicable to the
following three months. If the originating

                                      16
<PAGE>
 
Party also chooses to combine Interstate and Intrastate Toll Traffic on the same
trunk group, it will supply an auditable Percent Interstate Use ("PIU") report
quarterly, based on the previous three months' terminating traffic, and
applicable to the following three months. In lieu of the foregoing PLU and/or
PIU reports, the Parties may agree to provide and accept reasonable surrogate
measures for an agreed-upon interim period.

         5.6.4   Measurement of billing minutes for purposes of determining
terminating compensation shall be in conversation seconds.

     5.7     RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

     Reciprocal Compensation arrangements address the transport and termination
of Local Traffic. BA's delivery of Traffic to MFS that originated with a third
carrier is addressed in subsection 7.3. Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and termination of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

         5.7.1   Nothing in this Agreement shall be construed to limit either
Party's ability to designate the areas within which that Party's Customers may
make calls which that Party rates as "local" in its Customer Tariffs.

         5.7.2   The Parties shall compensate each other for transport and
termination of Local Traffic in an equal and symmetrical manner at the rates
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if
not set forth therein, in the applicable Tariff(s) of the terminating Party, as
the case may be. These rates are to be applied at the M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges,
including port or transport charges, shall apply for the termination of Local
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A.
When Local Traffic is terminated over the same trunks as Toll Traffic, any port
or transport or other applicable access charges related to the Toll Traffic
shall be prorated to be applied only to the Toll Traffic.

         5.7.3   The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs.

         5.7.4   Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5. 

                                      17
<PAGE>
 
         5.7.5   The designation of Traffic as Local or Toll for purposes
compensation shall be based on the actual originating and terminating points of
the complete end-to-end call, regardless of the carrier(s) involved in carrying
any segment of the call.

         5.7.6   Each Party reserves the right to measure and audit all Traffic
to ensure that proper rates are being applied appropriately. Each Party agrees
to provide the necessary Traffic data or permit the other Party's recording
equipment to be installed for sampling purposes in conjunction with any such
audit.

         5.7.7   The Parties will engage in settlements of alternate-billed
calls (e.g. collect, calling card, and third-party billed calls) originated or
authorized by their respective Customers in Virginia in accordance with the
terms of an appropriate billing services agreement for intraLATA intrastate
alternate-billed calls or such other arrangement as may be agreed to by the
Parties.


6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2).

     6.1     SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over
the Interconnections specified in Section 4 for the transmission and routing of
traffic between MFS Telephone Exchange Service Customers and Interexchange
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2     TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

         6.2.1   MFS shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from MFS's Customers.

         6.2.2   Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access to allow MFS's Customers to connect
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

         6.2.3   The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch MFS utilizes to provide Telephone Exchange
Service and Switched Exchange Access in a given LATA to an Access Tandem BA
utilizes to provide Exchange Access in such LATA.

         6.2.4   The Parties shall jointly determine which BA Access Tandem(s)
will be subtended by each MFS End Office Switch. MFS's End Office switch shall
subtend the BA Access Tandem that would have served the same rate center on BA's
network. Alternative configurations will be discussed as part of the Joint Plan.

                                      18
<PAGE>
 
     6.3     MEET-POINT BILLING ARRANGEMENTS

             6.3.1  MFS and BA will establish Meet-Point Billing arrangements
in order to provide a common transport option to Switched Access Services
Customers via an Access Tandem Switch in accordance with the Meet-Point Billing
guidelines contained in the OBF's MECAB and MECOD documents, except as modified
herein, and BA's Virginia Tariff Number 217, Section 2.4.8. The arrangements
described in this Section 6 are intended to be used to provide Switched Exchange
Access Service that originates and/or terminates on a Telephone Exchange Service
that is provided by either Party, where the transport component of the Switched
Exchange Access Service is routed through a Tandem Switch that is provided by
BA.

             6.3.2  In each LATA, the Parties shall establish MPB arrangements
between the applicable Rating Point/BA Local Serving Wire Center combinations.

             6.3.3  Interconnection for the MPB arrangement shall occur at the
BA-IP in the LATA, unless otherwise agreed to by the Parties.

             6.3.4. MFS and BA will use reasonable efforts, individually and
collectively, to maintain provisions in their respective state access tariffs,
and/or provisions within the National Exchange Carrier Association ("NECA")
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

             6.3.5  Each Party shall implement the "Multiple Bill/Single Tariff'
or "Multiple Bill/Multiple Tariff' option, as appropriate, in order to bill an
IXC for the portion of the jointly provided telecommunications service provided
by that Party.

             6.3.6  The rate elements to be billed by each Party are as set
forth in Schedule 6.3. The actual rate values for each Party's affected access
service rate element shall be the rates contained in that Party's own effective
federal and state access tariffs, or other document that contains the terms
under which that Party's access services are offered. The MPB billing
percentages for each Rating Point/BA Local Serving Wire Center combination shall
be calculated in accordance with the formula set forth in subsection 6.3.16
below.

             6.3.7  Each Party shall provide the other Party with the billing
name, billing address, and Carrier Identification Code ("CIC") of the IXC, and
identification of the IXC's Local Serving Wire Center in order to comply with
the MPB notification process as outlined in the MECAB document via facsimile
or such other media as the Parties may agree to.

             6.3.8  BA shall provide MFS with the Switched Access Detail Usage
Data (category 1101XX records) on magnetic tape or via such other media as the
Parties may agree to, no later than ten (10) business days after the date the
usage occurred.

             6.3.9  MFS shall provide BA with the Switched Access Summary Usage
Data (category 115OXX records) on magnetic tape or via such other media as the
Parties may agree, no

                                      19
<PAGE>
 
later than ten (10) business days after the date of its rendering of the bill to
the relevant IXC, which bill shall be rendered no less frequently than monthly.

             6.3.10  Each Party shall coordinate and exchange the billing
account reference ("BAR") and billing account cross reference ("BACR") numbers
or Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each
Party shall notify the other if the level of billing or other BAR/BACR elements
change, resulting in a new BAR/BACR number, or if the OCN changes.

             6.3.11. Errors may be discovered by MFS, the IXC or BA. Each Party
agrees to provide the other Party with notification of any errors it discovers
within two (2) business days of the date of such discovery. In the event of a
loss of data, both Parties shall cooperate to reconstruct the lost data and, if
such reconstruction is not possible, shall accept a reasonable estimate of the
lost data based upon prior usage data.

             6.3.12  Either Party may request a review or audit of the various
components of access recording up to a maximum of two (2) audits per calendar
year. All costs associated with each review and audit shall be borne by the
requesting Party. Such review or audit shall be conducted subject to
confidentiality protection and during regular business hours. A Party may
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

             6.3.13. Nothing contained in this subsection 6.3. shall create any
liability for damages, losses, claims, costs, injuries, expenses or other
liabilities whatsoever on the part of either Party (other than as may be set
forth in MECAB or in any applicable Tariff).

             6.3.14. The Parties shall not charge one another for the services
rendered or information provided pursuant to this subsection 6.3.

             6.3.15  MPB will apply for all traffic bearing the 500, 900,
800/888 (to the extent provided by an IXC) or any other non-geographic NPA which
may be likewise designated for such traffic in the future.

             6.3.16  In the event MFS determines to offer Telephone Exchange
Services in another LATA in which BA operates an Access Tandem Switch, BA shall
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for
the BA End Offices in the area where the MFS Rating Point(s) associated with the
NPA-NXX(s) to/from which the Switched Exchange Access Services are homed. The
MPB billing percentages for each new Rating Point/BA Local Serving Wire Center
combination shall be calculated according to the following formula:

                      a / (a + b) = MFS Billing Percentage
                                      and
                      b / (a + b) = BA Billing Percentage

               where:
               ------

                                      20
<PAGE>
 
               a = the airline mileage between the Rating Point and the actual
          point of interconnection for the MPB arrangement; and

               b = the airline mileage between the BA Local Serving Wire Center
          and the actual point of interconnection for the MPB arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange
Services and its calculation of the billing percentages which should apply for
such arrangement, as part of the notice required by subsection 4.4.1 above.
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS
shall confirm the new Rating Point/BA Local Serving Wire Center combination and
billing percentages. Nothing in this subsection 6.3.16 shall be construed to
limit MFS's ability to select to interconnect with BA in additional LATAs by
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

    6.4  800/888 TRAFFIC

    The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

         6.4.1.  When MFS delivers untranslated 800/888 calls to BA for
completion

                 (a)  to an IXC, BA shall:

                      (i)    Provide a MPB record in an industry standard format
                      to MFS; and

                      (ii)   Bill the IXC the appropriate BA query charge
                      associated with the call.

                 (b)  as an IntraLATA call to BA or another LEC in the LATA, BA
shall

                      (i)    Provide a copy record in an industry standard
                      format to MFS;

                      (ii)   Bill MFS the appropriate BA query charge associated
                      with the call; and

                      (iii)  Submit the call records to ITORP for payment by BA
                      or the LEC that is the 800/888 service provider of MFS's
                      and any intermediate LEC's Tariffed Exchange Access
                      charges and query charges.

                                      21
<PAGE>
 
          6.4.2   When BA delivers 800/888 calls originated by BA's or another
LEC's Customers to MFS for completion

                  (a)   to MFS in its capacity as an IXC, BA shall:

                        (i)    Bill MFS the appropriate BA query charge
                        associated with the call; and

                        (ii)   Bill MFS the appropriate FGD Exchange Access
                        charges associated with the call.

                  (b)   as an IntraLATA call to MFS in its capacity as a LEC,

                        (i)    BA shall submit the appropriate call records to
                        ITORP for payment by MFS of BA's (and another LEC's, if
                        appropriate) Tariffed Exchange Access charges; and

                        (ii)   MFS shall pay the originating LEC's appropriate
                        query charge associated with the call.


7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to MFS-originated Information
Services Traffic directed to an information services platform connected to BA's
network. At such time as MFS connects Information Services platforms to its
network, the Parties shall agree upon a suitable arrangement for BA-originated
Information Services Traffic.

          7.1.1  MFS shall route Information Services Traffic that originates on
its own network to the appropriate information services platform(s) connected to
BA's network. MFS will establish a dedicated trunk group to the BA information
services serving switch. This trunk group will be utilized to allow MFS to
route information service traffic originated on its network to BA.

          7.1.2  MFS shall provide an electronic file transfer or monthly
magnetic tape containing recorded call detail information to BA.

          7.1.3  BA shall provide to MFS via electronic file transfer or
magnetic tape or other means as available all necessary information to rate the
Information Services Traffic to MFS's Customers pursuant to the BA's agreements
with each information services provider. Information shall be provided in as
timely a fashion as practical in order to facilitate record review and reflect
actual prices set by the individual information services providers.

                                      22
<PAGE>
 
          7.1.4  MFS shall bill and collect such information services provider
charges and remit the amounts collected to BA less:

          (a)  The Information Services Billing and Collection fee set forth in
     Exhibit A; and

          (b)  An uncollectibles reserve calculated based on the uncollectibles
     reserve in BA's billing and collection agreement with the applicable
     information services provider; and

          (c)  Customer adjustments provided by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and
Customer adjustments to allow BA to pass through the adjustments to the
information services provider, and BA shall pass through such adjustments.
However, if the information services provider disputes such adjustments and
refuses to accept such adjustments, MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputed adjustments shall be solely
between MFS and the information services provider.

          7.1.5  Nothing in this Agreement shall restrict either Party from
offering to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

          7.1.6  The Parties may agree to separate arrangements for the billing
and compensation of variable rated (e.g. 970, 540) information services.
                                    - -

          7.1.7  The Information Services Traffic addressed herein does not
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1  Each Party shall offer LSV and VCI services to enable its
Customers to verify and/or interrupt calls of the other Party's Customers. In
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party
(Party A) and the responding Party (Party B) shall perform in accordance with
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to
be agreed upon between the Parties.

          7.2.2  The Party B operator shall only verify the status of the line
(LSV) or interrupt the line to inform the called party that there is a call
waiting. The Party B operator will not complete the telephone call of the
Customer initiating the LSV/VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable
charges apply whether or not the called party releases the line.

                                      23
<PAGE>
 
          7.2.3  Each Party's operator bureau shall accept LSV and VCI inquiries
from the operator bureau of the other Party in order to allow transparent
provision of LSV/VCI Traffic between the Parties' networks.

          7.2.4  Each Party shall route LSV/VCI Traffic inquiries over separate
direct trunks (and not the Local/IntraLATA/InterLATA Trunks) established between
the Parties' respective operator bureaus. Each Party shall offer interconnection
for LSV/VCI traffic at its Local Serving Wire Center, operator services Tandem
Office subtended by such Local Serving Wire Center, or other mutually agreed
point in the LATA. Separate LSV/VCI trunks delivered at the Local Serving Wire
Center will be directed to the operator services Tandem Office designated by
Party B. Unless otherwise mutually agreed, the Parties shall configure LSV/VCI
trunks over the Interconnection architectures in accordance with the terms of
Section 4, consistent with the Joint Grooming Plan. Party A shall outpulse the
appropriate NPA, ATC Code, and Routing Code (operator code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a
reciprocal local traffic exchange arrangement (either via written agreement or
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as
quickly as commercially reasonable following the Effective Date and to provide
copies thereof to BA, but continues to utilize BA's Transit Service for the
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC,
MFS shall, in addition to paying the rate set forth in Exhibit A for said
Transit Service, pay BA any charges or costs such terminating third party
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred by
                                       ----
BA in delivering or terminating such Traffic and/or resulting from MFS's failure
to secure said reciprocal local traffic exchange arrangement. BA will, upon
request, provide MFS with all reasonable cooperation and assistance in obtaining
such arrangements. The Parties agree to work cooperatively in appropriate
industry fora to promote the adoption of reasonable industry guidelines relating
to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will
deliver each call to each involved network with CCS and the appropriate
Transactional Capabilities Application Part ("TCAP") message to facilitate full
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and
exchange records between the Parties and with the terminating carrier to
facilitate the billing process to the originating network.

                                      24
<PAGE>
 
          7.3.4  Transit Traffic shall be routed over the Traffic Exchange
Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

          7.4.1  MFS will interconnect to the BA 911/E911 selective routers or
911 Tandem Offices, where available, which serve the areas in which MFS provides
Telephone Exchange Services, for the provision of 911/E911 services and for
access to all subtending Public Safety Answering Points ("PSAP"). In such
situations, BA will provide MFS with the appropriate CLLI codes and
specifications of the Tandem Office serving area. In areas where E911 is not
available, MFS and BA will negotiate arrangements to connect MFS to the 911
service.

          7.4.2  Path and route diverse interconnections for 91l/E911 shall be
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed,
and as required by law or regulation.

          7.4.3  Upon request, BA will provide MFS with the following:

          (a)    an electronic interface, when available, through which MFS
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911
     information such as name, address, and telephone number in writing for BA's
     entry into the 911 database system. Any 911-related data exchanged between
     the Parties shall conform to the National Emergency Number Association
     standards;

          (b)    a file containing the Master Street Address Guide ("MSAG"), as
     may be updated from time to time, for the exchanges or communities
     specified;

          (c)    a return of any MFS E911 data entry files containing errors, so
     that MFS may ensure the accuracy of the Customer records; and

          (d)    PSAP 911 Tandem information.

          7.4.4  In cases where a Customer of one Party elects to discontinue
its service and become the Customer of the other Party ("Party B") but desires
to retain its original telephone number pursuant to an INP or PNP arrangement,
Party B will outpulse the telephone number to which the call has been forwarded
(i.e. the Customer's ANI) to the 911 Tandem Office. Party B will also provide
 - -
the 911 database with both the forwarded number and the directory number, as
well as the appropriate address information of the Customer.

          7.4.5  BA and MFS will use their best efforts to facilitate the
prompt, robust, reliable and efficient interconnection of MFS systems to the 
911/E911 platforms.

                                      25
<PAGE>
 
          7.4.6  BA and MFS will work cooperatively to arrange meetings with 
PSAPs to answer any technical questions the PSAPs, or county or municipal
coordinators may have regarding the 911/E911 arrangements. BA shall assist MFS
in identifying the appropriate person in each municipality for the purpose of
obtaining the ten-digit subscriber number of each PSAP.

          7.4.7  The Parties acknowledge that the provision of INP, until PNP
with full 911 compatability is available, creates a special need to have the
Automatic Location Identification ("ALI") screen reflect two number: the "old"
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification
("TCI") of the company that provides service to the calling line as part of the
ALI display. Until such time as TCI is operational, however, BA and MFS agree to
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8  MFS will compensate BA for connections to its 911/E911
pursuant to Exhibit A.

          7.4.9  MFS will comply with all applicable rules and regulations
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY  Ancillary Traffic that may be terminated
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise
adversely affect in any manner either Party's right to employ or to request and
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code
Assignment Guidelines, as may be amended from time to time, or to establish, by
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX
codes. Until such time as number administration is provided by a third party, BA
shall provide MFS access to telephone numbers by assigning NXX codes to MFS in
accordance with such Assignment Guidelines.

     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing
Guide ("LERG") in order to recognize and route traffic to the other Party's
assigned NXX codes at all times. Neither Party shall impose any fees or charges
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, MFS shall
adopt the Rate Center Areas and Rate Center Points that the Commission has
approved for BA, in all areas where BA and

                                      26
<PAGE>
 
MFS service areas overlap, and MFS shall assign whole NPA-NXX codes to each
Rate Center unless the LEC industry adopts alternative methods of utilizing NXXs
in the manner adopted by the NANP.

     8.4  MFS will also designate a Routing Point for each assigned NXX code.
MFS shall designate one location for each Rate Center Area as the Routing Point
for the NPA-NXXs associated with that Area, and such Routing Point shall be
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in
this Agreement is intended to, and nothing in this Agreement shall be construed
to, in any way constrain MFS's choices regarding the size of the local
calling area(s) that MFS may establish for its Customers, which local calling
areas may be larger than, smaller than, or identical to, BA's local calling
areas.


9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance
                                                           - -
contact numbers, network information, information required to comply with law
enforcement and other security agencies of the Government) to achieve this
desired reliability. In addition, the Parties will work cooperatively to apply
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that
may be agreed to between the Parties and to employ characteristics and methods
of operation that will not interfere with or impair the service or any
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of
operation used by Party B will or may interfere with or impair its provision of
services, Party A shall have the right to discontinue Interconnection subject,
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days' prior written
notice of interference or impairment or potential interference or impairment
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice
provided to Party B under (a) above to the appropriate federal and/or state
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall
not be required in emergencies and Party A may immediately discontinue
Interconnection if reasonably necessary

                                      27
<PAGE>
 
to meet its obligations. In such case, however, Party A shall use all reasonable
means to notify Party B and the appropriate federal and/or state regulatory
bodies.

          9.3.4     Upon correction of the interference or impairment, Party A 
will promptly renew the Interconnection. During such period of discontinuance, 
there will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

          9.4.1     The Interconnection provided hereunder may be discontinued 
by either Party upon thirty (30) days written notice to the other for repeated 
or willful violation of and/or a refusal to comply with this Agreement. The 
Party discontinuing will notify the appropriate federal and/or state regulatory 
bodies concurrently with the notice to the other Party of the prospective 
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or 
service being provided by a Party hereunder, the providing Party will follow 
procedures for isolating and clearing the outage or trouble that are no less 
favorable than those that apply to comparable arrangements, facilities, or 
services being provided by the providing Party to any other carrier whose 
network is connected to that of the providing Party. MFS and BA may agree to 
modify those procedures from time to time based on their experience with 
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES -- SECTION 251(C)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN. On or before December
1, 1996, unless the Parties agree to a different date, MFS and BA shall jointly 
develop a grooming plan (the "Joint Plan") which shall define and detail, inter 
                                                                          ----- 
alia,
- ----

          (a)  modifications to the agreement on physical architecture 
     consistent with the guidelines defined in Section 4;

          (b)  standards to ensure that Interconnection trunk groups experience
     a grade of service, availability and quality which is comparable to that
     achieved on interoffice trunks within BA's network and in accord with all
     appropriate relevant industry-accepted

                                      28

<PAGE>
 
     quality, reliability and availability standards. Trunks provided by either 
     Party for Interconnection services will be engineered using a design 
     blocking objective of B.01;

          (c)  the respective duties and responsibilities of the Parties with
     respect to the administration and maintenance of the trunk groups,
     including, but not limited to, standards and procedures for notification
     and discoveries of trunk disconnects;

          (d)  disaster recovery provision escalations;

          (e)  migration from one-way to two-way Interconnection Trunks upon 
     mutual agreement of the Parties;

          (f)  actual meet point locations on the SONET system; and

          (g)  such other matters as the Parties may agree.

     10.2 INSTALLATION, MAINTENANCE, TESTING AND REPAIR.  BA's standard 
intervals for Feature Group D Switched Exchange Access Services will be used for
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of its facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its 
inability to do so and will negotiate such intervals in good faith. The Parties 
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than 
those applicable to comparable arrangements, facilities, or services being 
provided by such Party to any other carrier whose network is connected to that 
of the providing Party.

     10.3 FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING.  Within sixty (60)
days of executing this Agreement, MFS shall provide BA a one (1) year traffic
forecast. This initial forecast will provide the amount of traffic to be
delivered to each of BA's End Offices affected by the exchange of traffic. The
forecast shall be updated and provided to BA on a quarterly basis, and include
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator
services, 911, etc.), code (identifies trunk group), A location/Z location (CLLI
codes), interface type (e.g., DS1), and trunks in service each year
(cumulative).

          10.3.1 Initial Forecast/Trunking Requirements. Because BA's trunking 
                 --------------------------------------
requirements will, at least during an initial period, be dependent on the 
customer segments and service segments within customer segments to whom MFS 
decides to market its services, BA will be largely dependent on MFS to provide 
accurate trunk forecasts for both inbound (from BA) and outbound (from MFS) 
traffic. BA will, as an initial matter and upon request, provide the same 
number of trunks to terminate local traffic to MFS as MFS provides to terminate 
local traffic to BA, unless MFS expressly identifies particular situations that 
are expected to produce traffic that is substantially skewed in either the 
inbound or outbound direction, in which case BA will provide the number of 
trunks MFS suggests. Upon the establishment of any new set of trunks for traffic
from BA to MFS, BA will monitor traffic for ninety (90) days, and will, as

                                      29

<PAGE>
 
necessary at the end of that period, either augment trunks or disconnect 
trunks, based on the application of reasonable engineering criteria to the 
actual traffic volume experienced. If, after such 90-day period, BA has 
determined that the trunks are not warranted by actual traffic volumes, then, on
ten (10) days' written notice, BA may hold MFS financially responsible for such 
trunks retroactive to the start of the 90-day period until such time as they are
justified by actual traffic volumes, based on the application of reasonable 
engineering criteria. To the extent that BA requires MFS to install trunks for 
delivery of traffic to BA, MFS may apply the same procedures with respect to 
BA's trucking requirements.

11.0 UNBUNDLED ACCESS - SECTION 251(C)(3).

     To the extent required of each Party by Section 251 of the Act, each Party
shall offer to the other Party nondiscriminatory access to Network Elements on
an unbundled basis at any technically feasible point. BA shall unbundle and
separately price and offer Network Elements such that MFS will be able to lease
and interconnect to whichever of the Network Elements MFS requires, and to
combine the BA-provided elements with any facilities and services that MFS may
itself provide, except that MFS shall not recombine Network Elements purchased
from BA for use as a substitute for the purchase at wholesale rates of
Telecommunications Services that BA provides unless otherwise mandated by the
FCC or the Commission or agreed to by BA with other carriers.

     11.1 UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

     Subject to subsection 11.4, BA shall allow MFS to access the following ULL
types (in addition to those ULLs available under applicable tariffs) unbundled
from local switching and local transport in accordance with the terms and
conditions set forth in this subsection 11.1.

          11.1.1 "2-Wire Analog Voice Grade ULL" or "Analog 2W" provides an
effective 2-wire channel with 2-wire interfaces at each endthat is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals and loop-
start signaling. The service is more fully described in Bell Atlantic TR-72565.
If "Customer-Specified Signaling" is requested, the service will operate with
one of the following signaling types that may be specified when the service is
ordered: loop-start, ground-start, loop-reverse-battery, and no signaling. The
service is more fully described in Bell Atlantic TR-72570.

          11.1.2 "4-Wire Analog Voice Grade ULL" or "Analog 4W" provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The
service will operate with one of the following signaling types that may be
specified when the service is ordered: loop-start, ground-start, loop-reverse-
battery, duplex, and no signaling. The service is more fully described in Bell
Atlantic TR-72570.

          11.1.3 "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides a 
channel with 2-wire interfaces at each end that is suitable for the transport of
160 kbps digital services using the ISDN 2B1Q line code.

                                      30

<PAGE>
 
          11.1.4 "2-Wire ADSL-Compatible ULL" or "ADSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of digital
signals up to 6Mbps toward the Customer and up to 640 kbps from the Customer. BA
will offer ADSL-Compatible ULLs only when the technology BA uses to provide such
ULLs is compatible with that of MFS. In addition, ADSL-Compatible ULLs will be
available only where existing copper facilities can meet applicable industry
standards.

          11.1.5 "2-Wire HDSL-Compatible ULL" or "HDSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of 784 
kbps digital signals simultaneously in both directions using the 2B1Q line code.
HDSL compatible ULLs will be available only where existing copper facilities can
meet the specifications.

          11.1.6 "4-Wire HDSL-Compatible ULL" or "HDSL 4 W" provides a channel 
with 4-wire interfaces at each end. Each 2-wire channel is suitable for the 
transport of 784 kbps digital signals simultaneously in both directions using 
the 2B1Q line code. HDSL compatible ULLs will be available only where existing 
copper facilities can meet specfications.

          11.1.7 ULLs will be offered on the terms and conditions specified 
herein and on such other terms in applicable Tariffs that are not inconsistent 
with the terms and conditions set forth herein. BA shall make ULLs available to 
MFS at the rates specified by the Commission, as amended from time to time, 
subject to the provisions of subsection 11.1.8 below.

          11.1.8 BA will make Analog 2-Wire ULLs available for lease by MFS in 
accordance with the schedule set forth in Schedule 3.0. BA will make BRI ISDN 
and Analog 4W ULLs available for lease by MFS by the later of January 1, 1997, 
or the date when the ULL milestone contained in Schedule 3.0 is achieved in the 
LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease by MFS
as soon as practicable, but in any event no later than six months, after BA 
makes the services using equivalent loop facilities commercially available to 
its own end-user Customers in Virginia. Upon request by either BA or MFS, the 
Parties shall agree upon a reasonable schedule and location for a technical and 
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s) 
may, by mutual agreement, be conducted in any jurisdiction in which affiliates 
of BA and MFS both operate. Upon successful completion of such trial(s), the 
Parties shall agree upon an implementation schedule for the ULL type(s) subject 
to such trial(s), which schedule shall begin no later than ninety (90) days
after successful completion of such trial(s).

     11.2 PORT TYPES

     BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.
                                            ---- ----

                                      31

<PAGE>
 
     11.3  TRUNK SIDE LOCAL TRANSPORT

     BA shall provide MFS local transport from the trunk side of BA's Central 
Office Switches using private lines and special access services unbundled from 
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

     11.4  LIMITATIONS ON UNBUNDLED ACCESS

           11.4.1 Unless otherwise mandated by the FCC or the Commission or 
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under 
applicable tariffs.

           11.4.2 BA shall not be required to make available ULLs and Ports 
where such ULLs and Ports are available.

           11.4.3 MFS shall access BA's unbundled Network Elements specifically 
identified in this Agreement via Collocation in accordance with Section 13 at 
the BA Wire Center where those elements exist and each ULL or Port shall be 
delivered to MFS's Collocation by means of a Cross Connection.

           11.4.4 BA shall provide MFS access to its Unbundled Local Loops at
each of BA's Wire Centers for loops terminating in that Wire Center. In
addition, if MFS requests one or more ULLs provisioned via Integrated Digital
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA
shall, where available, move the requested ULL(s) to a spare, existing physical
ULL at no additional charge to MFS.  If, however, no spare physical ULL is
available, BA shall within three (3) business days of MFS's request notify MFS
of the lack of available facilities. MFS may then at its discretion make a
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the
ULL concentration site point. Alternatively, MFS may choose to avail itself of
BA's Special Construction services, as set forth in Exhibit A, for the
provisioning of such ULL(s). Notwithstanding anything to the contrary in this
Agreement, the provisioning intervals set forth in subsection 11.6 and the
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this
subsection 11.4.4.

           11.4.5 If MFS orders a ULL type and the distance requested on such 
ULL exceeds the transmission characteristics in applicable technical references,
distance extensions may be required and additional rates and charges shall 
apply as set forth in Exhibit A or applicable Tariffs.

           11.4.6 BA will exercise all reasonable efforts to ensure that the 
service intervals that apply to ULLs and unbundled Ports are comparable to the 
(i) repair intervals that apply to the bundled dial tone line service, and (ii) 
installation intervals that apply to other BA-coordinated services, except as 
provided in Section 27. Although BA will make commercially

                                      32

 





<PAGE>
 
reasonable efforts to ensure that ULLs and unbundled ports meet specified or 
agreed-upon technical standards, BA makes no warranty that the ULLs or unbundled
Ports supplied by BA hereunder will be compatible with the services MFS may 
offer to its Customers if they are used in a manner not contemplated by the 
Parties.

     11.5  AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

           11.5.1 BA shall, upon request of MFS, and to the extent technically 
feasible, provide to MFS access to its Network Elements on an unbundled basis 
for the provision of MFS's Telecommunications Service. Any request by MFS for 
access to an BA Network Element that is not already available shall be treated 
as a Network Element Bona Fide Request. MFS shall provide BA access to its 
Network Elements as mutually agreed by the Parties or as required by the 
Commission or FCC.

           11.5.2 A Network Element obtained by one Party from the other Party 
under this subsection 11.5 may be used in combination with the facilities of the
requesting Party only to provide a Telecommunications Service, including
obtaining billing and collection, transmission, and routing of the
Telecommunications Service.

           11.5.3 Notwithstanding anything to the contrary in this subsection 
11.5, a Party shall not be required to provide a proprietary Network Element to
the other Party under this subsection 11.5 except as required by the Commission 
or FCC.

     11.6  PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs. These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA 
to MFS and from MFS to BA.

           11.6.1 Upon request by MFS, BA will apply the following coordination 
procedures to conversions of live Telephone Exchange Services to ULLs. 
Coordinated cutover charges will apply to any such arrangement, only to the 
extent provided by Section A.4.a of Exhibit A. If MFS elects not to request 
coordinated cutover, BA will process MFS's request in the normal course and 
subject to the normal installation intervals.

           11.6.2 MFS shall request ULLs from BA by delivering to BA a valid 
electronic transmittal service order (when available) or another mutually 
agreed-upon type of service order. Such service order shall be provided in 
accordance with industry format and specifications or such format and 
specifications as may be agreed to by the Parties. Within forty-eight (48) hours
of BA's receipt of such valid service order, BA shall provide MFS the firm order
commitment date according to the Performance Interval Dates set forth in 
Schedule 27 by which the ULLs covered by such service order will be installed. 
In addition, BA shall provide MFS with the relating ULL design information, if 
available, at least forty eight (48) hours prior to the scheduled cutover time

                                      33
<PAGE>
 
          11.6.3    On each ULL order in a Wire Center, MFS and BA will agree on
a cutover time at least forty eight (48) hours before that cutover time. The 
cutover time will be defined as a 15-30 minute window within which both the MFS 
and BA personnel will make telephone contact to complete the cutover.

          11.6.4    Within the appointed 15-30 minute cutover time, the MFS 
person will call the BA organization designated to coordinate cross-connection
work and when the BA organization is reached in that interval such work will be
promptly performed.

          11.6.5    If MFS requires a change in scheduling, it must contact BA 
to issue a supplement to the original order. The negotiations process to 
determine the date and time of cutover will then be reinitiated as usual.

          11.6.6    If MFS person is not ready within the appointed interval and
if MFS had not called to reschedule the work at least two (2) hours prior to the
start of the interval, MFS shall be liable for the non-recurring charge for the 
unbundled elements scheduled for the missed appointment. In addition, 
non-recurring charges for the rescheduled appointment will apply.

          11.6.7    If BA is not available or not ready at any time during the 
appointed 15-30 minute interval, MFS and BA will reschedule and BA will waive 
the non-recurring charge for the unbundled elements originally scheduled for 
that interval, whenever those unbundled elements are actually cutover pursuant 
to an agreed-upon rescheduling.

          11.6.8    The standard time expected from disconnection of a live 
Telephone Exchange Service to the connection of the unbundled element to the MFS
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all 
orders consisting of fifteen (15) ULLs or less. Orders involving more than 
fifteen (15) ULLs will require a negotiated interval.

          11.6.9    If unusual or unexpected circumstances prolong or extend the
time required to accomplish the coordinated cutover, the Party responsible for 
such circumstances is responsible for the reasonable labor charges of the other 
Party. Delays caused by the Customer are the responsibility of MFS.

          11.6.10   If MFS has ordered INP as part of an ULL installation, BA 
will coordinate implementation of INP with the ULL installation. BA's provision 
of unbundled elements shall in all cases be subject to the availability of 
suitable facilities, to the extent permitted by Section 251 of the Act.

          11.6.11   If MFS requests or approves a BA technician to perform 
services on the network side of the Rate Demarcation Point beyond normal 
installation of the ULLs covered by the service order, BA may charge MFS for any
additional and reasonable labor charges to perform such services. BA may also 
charge MFS its normal overtime rates for services MFS requests to be performed 
outside of BA's normal business hours (M-F, 9 am to 5 pm, E.S.T.).

                                      34
<PAGE>
 
     11.7 MAINTENANCE OF UNBUNDLED LOCAL LOOPS

     If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a dispatch,
(iii) BA dispatches a technician, and (iv) such trouble was not caused by BA's
facilities or equipment, then MFS shall pay BA a per-trip charge charge and
labor charges per quarter hour increments for time associated with said
dispatch, as set forth in Exhibit A. In addition this charge also applies in
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA with appropriate dispatch information based on their test results.
If, as the result of MFS instructions, BA is erroneously requested to dispatch
within the Central Office, BA may levy on MFS an appropriate charge.

     11.8 RATES AND CHARGES

     BA shall charge the non-recurring and monthly recurring rates for unbundled
Local Loops and other Network Elements set forth in Exhibit A.


12.0 RESALE -- SECTIONS 251(C)(4) AND 251(B)(1).

     12.1 AVAILABILITY OF RETAIL RATES FOR RESALE

     Each Party shall make available its Telecommunications Services for resale
at retail rates to the other Party in accordance with Section 251(b)(1) of the
Act.

     12.2 AVAILABILITY OF WHOLESALE RATES FOR RESALE

     BA shall make available to MFS for resale at wholesale rates set forth in 
Exhibit A all Telecommunications Services that BA provides at retail to 
Customers that are not Telecommunications Carriers. Such services shall be 
provided in accordance with the terms of the applicable retail services 
Tariff(s), including, without limitation, user or user group restrictions, as 
the case may be, subject to the requirement that such restrictions shall in all 
cases comply with the requirements of Section 251 of the Act regarding 
restrictions on resale. In addition, BA and MFS shall each allow the resale by 
the other of all Telecommunications Services that are offered primarily or 
entirely to other Telecommunications Carriers (e.g., Switched and special 
                                               - - 
Exchange Access Services) at the rates already applicable to such services. BA
shall also allow the resale by MFS of such other non-Telecommunications Services
as BA, in its sole discretion, determines to provide for resale under terms and
conditions to be agreed to by the Parties. If MFS requests resale at wholesale
rates of Telecommunications Services that BA provides at retail to Customers
that are not Telecommunications Carriers before April 1, 1997, the Parties shall
negotiate and agree upon the terms and conditions for ordering, provisioning,
billing, and maintaining such resale arrangements before MFS submits any orders
for such resale, which terms and conditions are unlikely to rely on automated
interfaces. During the period before April 1, 1997, the Parties shall negotiate
and agree upon, in the form of a separate agreement to be appended hereto,
resale arrangements to apply after that date. Such arrangements shall, to the
extent feasible and

                                      35

<PAGE>
 
economically reasonable, employ automated interfaces for ordering, provisioning,
billing, and maintaining resold accounts. The Parties may also agree to 
negotiate term and/or volume discounts for resold services.


13.0 COLLOCATION - SECTION 251(c)(6).

     13.1 BA shall offer to MFS Physical Collocation of equipment necessary for 
Interconnection (pursuant to Section 4) or for access to unbundled Network 
Elements (pursuant to Section 11.0), except that BA may offer only Virtual 
Collocation if BA demonstrates to the Commission that Physical Collocation is 
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for 
the purpose of Interconnection with facilities or services of BA or access to 
unbundled Network Elements of BA, except as otherwise mutually agreed to in 
writing by the Parties or as required by the FCC or the Commission, subject to 
applicable federal and state Tariffs.

     13.2 Although not required to do so by Section 251(c)(6) of the Act, by 
this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either 
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to 
Section 4) on a non-discriminatory basis and at comparable rates, terms and
conditions as MFS may provide to other third parties. MFS shall provide such
Collocation subject to applicable Tariffs.

     13.3 Where MFS is Virtually Collocated on the date hereof on a premise that
was initially prepared for Physical Collocation for MFS, MFS may elect to (i) 
retain its Virtual Collocation in that premises, and/or (ii) establish Physical 
Collocation in that premises pursuant to current procedures and applicable 
Tariffs. BA will not assess to MFS non-recurring charges for central office 
common area construction to transition existing virtual collocation arrangements
to physical collocation arrangements in offices where MFS previously paid such 
charges. BA will also waive cage construction charges for cages of the same size
originally paid for by MFS. MFS shall coordinate with BA for rearrangement of 
MFS's equipment, facilities, and circuits. All applicable Physical Collocation 
recurring charges shall apply.

     13.4 Where MFS is Virtually Collocated on the date hereof on a premise that
was initially prepared for MFS as Virtual Collocation, MFS may elect to (i) 
retain its Virtual Collocation in that premises, or (ii) unless it is not 
practical for technical reasons or because of space limitations, convert its 
Virtual Collocation at such premises to Physical Collocation, in which case MFS 
shall coordinate the construction and rearrangement with BA of its equipment, 
facilities, and circuits, and for which MFS shall pay BA at applicable Tariff
rates. In addition, all Physical Collocation recurring charges shall apply.

     13.5 For both Physical Collocation and Virtual Collocation, the Collocating
Party shall provide its own or third-party leased transport facilities and 
terminate those transport facilities in equipment located in its Physical 
Collocation space, or in its virtually collocated equipment, at the Housing 
Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

                                      36
<PAGE>
 
     13.6  Collocation shall occur under the terms of each Party's applicable
and available Tariffs. Collocation is offered for network Interconnection
between the Parties. Unless otherwise agreed to by the Parties or either Party
is required by applicable law to permit on its collocated premises, neither
Party shall use a Collocation Arrangement to directly interconnect with a third
party's equipment or facilities collocated at the same location.


                           SECTION 251(b) PROVISIONS

14.0  NUMBER PORTABILITY -- SECTION 251(B)(2).

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability
("LTNP") on a reciprocal basis to each other to the extent technically feasible,
and in accordance with rules and regulations as from time to time prescribed by
the FCC and/or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the
industry pursuant to regulations issued by the FCC and/or the Commission, the
Parties agree to reciprocally provide Interim Number Portability to each other
at the prices listed in Exhibit A. Such agreed-upon prices for INP are not
intended to reflect either Party's views on the cost recovery mechanisms being
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable
FCC and/or Commission order(s) or regulations mandating the adoption of a
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as
practically possible while minimizing interruption or degredation of service to
their respective Customers. Once PNP is implemented, either Party may withdraw,
at any time and at its sole discretion, its INP offerings, subject to advance
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant
to FCC or Commission regulation, both Parties agree to conform and provide such
PNP. To the extent PNP rates or cost recovery mechanisms are not established by
the applicable FCC or Commission order or regulation mandating the adoption of
PNP, the Parties will negotiate in good faith the charges or cost recovery
mechanism for PNP service at such time as a PNP arrangement is adopted by the
Parties.

          14.1.4  Under either an INP or PNP arrangement, MFS and BA will
implement a process to coordinate LTNP cutovers with ULL conversions (as
described in Section 11 of this Agreement).

                                      37
<PAGE>
 
     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1  A Customer of one Party ("Party A") elects to become a
Customer of the other Party ("Party B"). The Customer elects to utilize the
original telephone number(s) corresponding to the Telephone Exchange Service(s)
it previously received from Party A, in conjunction with the Telephone Exchange
Service(s) it will now receive from Party B. Upon receipt of a service order
from Party B requesting assignment of the number(s) to Party B, Party A will
implement an arrangement whereby all calls to the original telephone number(s)
will be forwarded to a new telephone number(s) designated by Party B, only
within the same Exchange Area as the original telephone number(s). Party A will
route the forwarded traffic to Party B over the appropriate traffic exchange
trunk groups.

          14.2.2  Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties, Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3  Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated 
with those forwarded numbers as directed by Party B. In addition, Party A will 
update the retained numbers in the LIDB with the screening options provided by 
Party B on a per order basis. Party B shall determine which of the screening 
options offered by Party A should apply to the Party B Customer account.

          14.2.4  Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          14.2.5  Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a 
third party that is authorized to act on behalf of the Customer. Party A shall 
provide notification to Party B of third party orders affecting the INP service 
of a Party B customer. The Parties agree to work cooperatively to develop 
procedures or adopt industry standards or practices concerning the initiation 
and termination of INP service in a multi-carrier environment.

          14.2.6  The INP service offered herein shall not initially apply to 
NXX Codes 555, 915, 976, or 950, or for Feature Group A or coin telephone 
service. Upon request of either Party, provision of INP to these services will 
be mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any
arrangement that would render the forwarded call Toll Traffic.

                                      38




<PAGE>
 
          14.2.7  The ordering of INP arrangements and the exchange of screening
information shall be made in accordance with industry-accepted (e.g. OBF
                                                                - - 
developed) format and specifications to the extent they have been implemented by
the Parties.

     14.3  PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS
(FLEXDID) Either Party may also request INP through Direct Inward Dial Trunks
pursuant to any applicable Tariffs.

     14.4  PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION Where
either Party has activated an entire NXX for a single Customer, or activated a
substantial portion of an NXX for a single Customer, with the remaining numbers
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other
Party, the first Party shall cooperate with the second Party to have the entire
NXX reassigned in the LERG (and associated industry databases, routing tables,
etc.) to an End Office operated by the second Party. Such transfer will be
accomplished with appropriate coordination between the Parties and subject to
appropriate industry lead-times for movements of NXXs from one switch to
another. Neither Party shall charge the other in connection with this
coordinated transfer.

     14.5  RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed
numbers should be received by each Customer's chosen LEC as if each call to the
Customer had been originally addressed by the caller to a telephone number
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to
accomplish this objective where INP is employed, the Parties shall utilize the
process set forth in this subsection 14.5 whereby terminating compensation on
calls subject to INP will be passed from the Party (the "Performing Party")
which performs the INP to the other Party (the "Receiving Party") for whose
Customer the INP is provided.

          14.5.1  The Parties shall individually and collectively make best
efforts to track and quantify INP traffic between their networks based on the
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving
Party shall charge the Performing Party for each minute of INP traffic at the
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other
compensation charges for terminating such traffic, except as provided in
subsection 14.5.2.

          14.5.2  By the Interconnection Activation Date in each LATA, the
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as
Transit Traffic. On the date which is six (6) months after the Interconnection
Activation Date, and thereafter on each succeeding six month anniversary of such
Interconnection Activation Date, the Parties shall establish new INP traffic
percentages to be applied in the prospectives six (6) month period based

                                      39
<PAGE>
 
on the Performing Party's choice of actual INP traffic percentages from the
preceding six (6) month period or historic data of all traffic in the LATA.

          14.5.3  The INP Traffic Rate shall be equal to the sum of:

   (Recip Traffic percentage times the Reciprocal Compensation Rate set forth in
                             -----
                                   Exhibit A)
                                      plus
                                      ----

   (Intra Traffic percentage times Receiving Party's effective intrastate FGD 
                             -----
                                     rates)                                     
                                      plus
                                      ----

   (Inter Traffic percentage times Receiving Party's effective interstate FGD
                             -----
                                    rates).

     The Receiving Party shall compensate the Performing Party for its billing
and collection of charges for the intrastate and interstate FGD access services
provided by the Receiving Party to a third party through the greater of (i) the
difference between the intrastate and interstate FGD rates of the Receiving
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     14.6  RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this section 14, in
light of the FCC's First Report and Order and Further Notice of Proposed
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the
Parties stipulate and agree as follows:

          14.6.1  The rates listed in Exhibit A for the provision of INP are
appropriate amounts that each Party providing INP service should recover for the
provision of those INP functionalities in BA's operating territory. For the INP
functions it provides, each Party should be allowed to recover these amounts in
a manner consistent with any final FCC and/or Commission order on INP cost
recovery (such as a state-wide fund contributed to by all telecommunications
carriers).

          14.6.2  Within three (3) weeks of the Effective Date, the Parties will
jointly seek a Commission proceeding and ruling to develop and implement an INP
cost recovery mechanism consistent with the policy described in the Order and/or
any subsequent FCC or Commission decision.

          14.6.3  Until such time as a final FCC and/or Commission order,
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the other Party at the INP rates listed in Exhibit A. All revenues
received by the providing Party from its provision of INP service to the other
Party shall be placed into an escrow fund maintained by or tracked separately by
the providing Party. Upon issuance of a final FCC and/or Commission order, and
to the extent that it permits the Party providing INP to recover the associated
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal

                                      40
<PAGE>
 
to the amount it recovers from such fund for its provision of INP service to the
purchasing Party from the Effective Date, provided that in no event shall the
refund amount exceed the aggregate amount the providing Party has received from
the purchasing Party for INP services. If no such fund is ordered or
established, the providing Party shall retain the full amount of the revenues
tracked or held in escrow by it pursuant to this subsection 14.6.3.

          14.6.4 The Parties agree that neither Party waives its rights to 
advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.

15.0 DIALING PARITY -- SECTION 251(B)(3).

     BA and MFS shall each provide the other with nondiscriminatory access to 
such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4).

     Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C. (S)
224, as set forth in Exhibit A, where facilities are available, on terms,
conditions and prices comparable to those offered to any other entity pursuant
to each Party's applicable Tariffs. Where no such Tariffs exist, such access
shall be provided in accordance with the requirements of 47 U.S.C. (S) 224,
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C. (S) 224
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the
appropriateness of applying such changes on a retroactive basis to the date
hereof. If the Parties are unable to agree on the necessary changes to the
existing arrangements or the appropriateness of applying them on a retroactive
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.

17.0 DATABASES AND SIGNALING.

     17.1 Each Party shall provide the other Party with access to databases and
associated signaling necessary for call routing and completion by providing SS7
Common Channel Signaling (CCS) Interconnection in accordance with existing
Tariffs, and Interconnection and access 800/888 databases, LIDB, and any other
necessary databases in accordance with existing Tariffs and/or agreements with
other unaffiliated carriers, as set forth in the Exhibit A. Alternatively,
either Party may secure CCS Interconnection from a commercial

                                      41

<PAGE>
 
SS7 hub provider, and in the case the other Party will permit the purchasing 
Party to access the same databases as would have been accessible if the 
purchasing party had connected directly to the other Party's CCS network.

     17.2 The Parties will provide CCS Signaling to one another, where and as 
available, in conjunction with all Local Traffic, Toll Traffic, Meet Point 
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between 
their respective networks, including all CLASS features and functions, to the 
extent each Party offers such features and functions to its Customers. All CCS 
Signaling parameters will be provided upon request (where available), including 
called party number, calling party number, originating line information, calling
party category, and charge number. All privacy indicators will be honored. The 
Parties will follow all Ordering and Billing Forum-adopted standards pertaining 
to CIC/OZZ codes. Where CCS Signaling is not available, in-band multi-frequency 
(MF) wink start signaling will be provided. Any such MF arrangement will require
a separate local trunk circuit between the Parties' respective switches. In such
an arrangement, each Party will outpulse the full ten-digit telephone number of 
the called party to the other Party.

     17.3 Each Party shall provide trunk groups, where available and upon 
reasonable request, that are configured utilizing the B8ZS ESF protocol for 64 
kbps clear channel transmission to allow for ISDN interoperability between the 
Parties' respective networks.

     17.4 The following publications describe the practices, procedures and 
specifications generally utilized by BA for signaling purposes and is listed 
herein to assist the Parties in meeting their respective Interconnection 
responsibilities related to Signaling:

          (a)  Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC 
Networks - Signaling; and 

          (b)  Bell Atlantic Supplement Common Channel Signaling Network 
Interface Specification (BA-905).

     17.5 Each Party shall charge the other Party mutual and reciprocal rates 
for CCS Signaling as follows: BA shall charge MFS in accordance with Exhibit A 
hereto and applicable Tariffs; MFS shall charge BA rates equal to the rates BA 
charges MFS, unless MFS's Tariffs for CCS signaling provide for lower generally 
available rates, in which case MFS shall charge BA such lower rates.


18.0 COORDINATED SERVICE ARRANGEMENTS.

     18.1 INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its 
service provider form BA to MFS, or from MFS to BA, and does not retain its 
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides

                                      42
<PAGE>
 
details on the Customer's new number or provide other appropriate information to
the extent known. Referral Announcements shall be provided reciprocally, free of
charge to either the other Party or the Customer to the extent the providing
Party does not charge its own customers for such service, for a period of not
less than four (4) months after the date the Customer changes its telephone
number in the case of business Customers and not less than sixty (60) days after
the date the Customer changes its telephone number in the case of residential
Customers. However, if either Party provides Referral Announcements for
different periods than the above respective periods when its Customers change
their telephone numbers, such Party shall provide the same level of service to
Customers of the other Party.

     18.2  COORDINATED REPAIR CALLS. MFS and BA will employ the following
procedures for handling misdirected repair calls:

          18.2.1  MFS and BA will educate their respective Customers as to the
correct telephone numbers to call in order to access their respective repair
bureaus.

          18.2.2  To the extent Party A is identifiable as the correct provider
of service to Customers that make misdirected repair calls to Party B, Party B
will immediately refer the Customers to the telephone number provided by Party
A, or to an information source that can provide the telephone number of Party A,
in a courteous manner and at no charge. In responding to misdirected repair
calls, neither Party shall make disparaging remarks about the other Party, its
services, rates, or service quality.

          18.2.3  MFS and BA will provide their respective repair contact
numbers to one another on a reciprocal basis.

     18.3  CUSTOMER AUTHORIZATION. In order for either Party to order or
terminate service on behalf of the other Party's Customer, the requesting Party
must have proper written authorization from the customer in its files, and
provide a copy of such authorization to the other Party upon request. In the
event the requesting Party (i) fails to provide a copy of the Customer's proper
written authorization upon request, (ii) requests changes in the other Party's
Customer's service without having such authorization in its files, or (iii)
mistakenly changes the other Party's Customer's service, the requesting Party
shall be liable to the other Party for all charges that would be applicable to
the Customer for restoring service to the other Party.


19.0  DIRECTORY SERVICES ARRANGEMENTS

      BA will, upon request, provide the following directory services to MFS in
accordance with the terms set forth herein. In this Section 19, references to a
MFS Customer's "primary listing" shall mean such Customer's name, address, and
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP
arrangements with BA or any other carrier within the geographic area covered in
the relevant BA directory.

                                      43
<PAGE>
 
     19.1   DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

            19.1.1 BA will include the MFS Customer's primary listing in its
"White Pages" directory (residence and business listings) and "Yellow Pages"
directory (business listings) that cover the address of the Customer. Listings
of MFS's Customers will be interfiled with listings of BA's Customers and the
Customers of other LECs included in the BA directories. MFS will pay BA a non-
recurring charge as set forth in Exhibit A for providing such service for each
MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as the
case may be, for additional and foreign white page listings and other white
pages services for MFS's Customers. BA will not require a minimum number of
listings per order.

            19.1.2  BA will also include the MFS Customer's primary listing in
BA's directory assistance database on the same basis that BA's own Customers are
included, as well as in any electronic directories in which BA's Customers are
ordinarily included, for no charge other than the charges identified in
subsection 19.1.1.

            19.1.3  BA will distribute to MFS Customers copies of their primary
white pages and yellow pages directories at the same time and on the same basis
that BA distributes primary directories to its own Customers. BA will also
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional
directories from BA's Directory Fulfillment Centers, which Centers will provide
such additional directories for the same charges applicable to comparable
requests by BA Customers.

            19.1.4  BA will include all MFS NXX codes associated with the areas
to which each directory pertains, along with BA's own NXX codes in any maps or
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same
manner as BA's NXX information.

            19.1.5  MFS shall provide BA with daily listing information on all
new MFS Customers in the format required by BA or a mutually-agreed upon
industry standard format. The information shall include the Customer's name,
address, telephone number, the delivery address and number of directories to be
delivered, and, in the case of a business listing, the primary business heading
under which the business Customer desires to be placed, and any other
information necessary for the publication and delivery of directories. MFS will
also provide BA with daily listing information showing Customers that have
disconnected or terminated their service with MFS. BA will provide MFS with
confirmation of listing order activity within forty eight (48) hours.

            19.1.6  BA will accord MFS's directory listing information the same
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be
used solely for the purpose of providing directory services; provided, however,
that BA may use or license information contained in its directory listings for
direct marketing purposes so long as the MFS Customers are not separately
identified as such; and provided further that MFS may identify those of its
Customers that request

                                      44
<PAGE>
 
that their names not be sold for direct marketing purposes, and BA will honor 
such requests to the same extent as it does for its own Customers.

            19.1.7  BA or BA's publisher shall provide MFS with a report of all
MFS Customer listings ninety (90) days prior to directory publication in such
form and format as may be mutually agreed to by both Parties. Both Parties shall
use their best efforts to ensure the accurate listing of such information. BA
will also provide MFS, upon request, a copy of the BA listings standards and
specifications manual. In addition, BA will provide MFS with a listing of Yellow
Pages headings and directory close schedules on an ongoing basis.

            19.1.8  MFS will adhere to all practices, standards, and ethical
requirements of BA with regard to listings, and, by providing BA with listing
information, warrants to BA that MFS has the right to place such listings on
behalf of its Customers. MFS agrees that it will undertake commercially
practicable and reasonable steps to attempt to ensure that any business or
person to be listed is authorized and has the right (i) to provide the product
or service offered, and (ii) to use any personal or corporate name, trade name
or language used in the listing.

            19.1.9  BA's liability to MFS in the event of a BA error in or
omission of a listing shall be subject to the same limitations that BA's
liability to its own Customers are subject to. In addition, MFS agrees to take,
with respect to its own Customers, all reasonable steps to ensure that its and
BA's liability to MFS's Customers in the event of a BA error in or omission of a
listing shall be subject to the same limitations that BA's liability to its own
Customers are subject to.

     19.2 YELLOW PAGE MAINTENANCE. The Parties agree to work cooperatively to
ensure that Yellow Page advertisements purchased by Customers that switch their
service to MFS (including Customers utilizing MFS-assigned telephone numbers and
MFS Customers utilizing LTNP) are maintained without interruption. BA will allow
MFS Customers to purchase new Yellow Pages advertisements without
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. Ba and MFS may implement a commission program whereby MFS may, at
MFS's sole discretion, act as a sales, billing and collection agent for Yellow
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

     19.3   SERVICE INFORMATION PAGES. BA will include in the "Customer Guide" 
or comparable section of the applicable white pages directories listings 
provided by MFS for MFS's installation, repair and customer service and other 
essential service oriented information, as agreed by the Parties, including 
appropriate identifying logo. Such listings shall appear in the manner agreed to
by the Parties. BA shall not charge MFS for inclusion of this essential 
service-oriented information, but reserves the right to impose charges on other 
information MFS may elect to submit and BA may elect to accept for inclusion in 
BA's white pages directories. BA will provide MFS with the annual directory 
close dates and reasonable notice of any changes in said dates.

                                      45
<PAGE>
 
     19.4 DIRECTORY ASSISTANCE (DA); CALL COMPLETION

          19.4.1   Upon request, BA will provide MFS with directory assistance 
and/or call completion services substantially in accordance with the terms set
forth in the form Directory Assistance and Call Completion Services Agreement
appended hereto as Exhibit C.

          19.4.2   Also upon request, BA will provide to MFS operator services 
trunk groups, utilizing Feature Group D type signaling, with ANI, minus OZZ, 
when interconnecting to the BA operator services network.

20.0 COORDINATION WITH TARIFF TERMS

     20.1 The Parties acknowledge that some of the services, facilities, and
arrangements described herein are or will be available under and subject to the
terms of the federal or state tariffs of the other Party applicable to such
services, facilities, and arrangements. To the extent a Tariff of the providing
Party applies to any service, facility, and arrangement described herein, the
Parties agree as follows:

          20.1.1   Those rates and charges set forth in Exhibit A for the
services, facilities, and arrangements described herein that are designated with
an asterisk shall remain fixed for the initial term of the Agreement,
notwithstanding that such rates may be different from those contained in an
effective, pending, or future Tariff of the providing Party (including any
changes to such Tariff subsequent to the Effective Date). Those rates and
charges for services, facilities, and arrangements that are not designated with
an asterisk, and reference or are identical to a rate contained in an existing
Tariff of the providing Party, shall conform with those contained in the then-
prevailing Tariff and vary in accordance with any changes that may be made to
the Tariff rates and charges subsequent to the Effective Date. Even the asterisk
fixed rates and charges shall be changed to reflect any changes in the Tariff
rates and charges they reference, however, if the Parties agree to adopt the
changed Tariff rates and charges.

     20.2 Except with respect to the rates and charges described in subsection
20.1 above, all other terms contained in an applicable Tariff of the providing
Party shall apply in connection with its provision of the particular service,
facility, and arrangement hereunder.

21.0 INSURANCE

     21.1 MFS shall maintain, during the term of this Agreement, all insurance 
and/or bonds required by law and necessary to satisfy its obligations under this
Agreement, including, without limitation, its obligations set forth in Section 
25 hereof. At a minimum and without limiting the foregoing covenant, MFS shall 
maintain the following insurance:

          (a)  Commercial General Liability Insurance, on an occurrence basis, 
     including but not limited to, premises-operations, broad form property
     damage, products/completed

                                      46


<PAGE>
 
     operations, contractual liability, independent contractors, and personal 
     injury, with limits of at least $1,000,000 combined single limit for each 
     occurrence.

          (b)  Automobile Liability, Comprehensive Form, with limits of at least
     $500,000 combined single limit for each occurrence.

          (c)  Excess Liability, in the umbrella form, with limits of at least 
     $15,000,000 combined single limit for each occurrence.

          (d)  Worker's Compensation Insurance as required by law and Employer's
     Liability Insurance with limits of not less than $1,000,000 per occurrence.

     21.2 MFS shall name BA as an additional insured on the foregoing insurance.
MFS agrees that MFS's insurer(s) and anyone claiming by, through, under or on 
behalf of MFS, shall have no claim, right of action, or right of subrogation, 
against BA,  BA's affiliated companies, or the directors, officers or employees 
of BA or BA's affiliated companies, based on any loss or liability insurable 
under the foregoing insurance.

     21.3 MFS shall, within two (2) weeks of the date hereof and on a quarterly
basis thereafter, furnish certificates or other adequate proof of the foregoing
insurance. The certificates or other proof of the foregoing insurance shall be
sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court House
Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall require its
agents, representatives, or contractors, if any, that may enter upon the
premises of BA or BA's affiliated companies to maintain similar and appropriate
insurance and, if requested, to furnish BA certificates or other adequate proof
of such insurance. Certificates furnished by MFS or MFS's agents,
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to
cancellation of, or any material change in, the insurance."


22.0 TERM AND TERMINATION.

     22.1 This Agreement shall be effective as of the date first above written
and continue in effect until July 1, 1999, and thereafter the Agreement shall
continue in force and effect unless and until terminated as provided herein.
Upon the expiration of the initial term, either Party may terminate this
Agreement by providing written notice of termination to the other Party, such
written notice to be provided at least ninety (90) days in advance of the date
of termination. In the event of such termination, those service arrangements
made available under this Agreement and existing at the time of termination
shall continue without interruption under (a) new agreement executed by the
Parties, (b) standard Interconnection terms and conditions approved and made
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of
this Agreement on a month-to-month basis until such time as (a), (b), or (c)
becomes available.

                                      47


<PAGE>
 
     22.2 For service arrangements made available under this Agreement and
existing at the time of termination, if the standard Interconnection terms and
conditions or Tariff terms and conditions result in the non-terminating Party
physically rearranging facilities or incurring programming expense, the non-
terminating Party shall be entitled to recover such rearrangement or programming
costs, from the terminating Party. By mutual agreement, the Parties may jointly
petition the appropriate regulatory bodies for permission to have this Agreement
supersede any future standardized agreements or rules as such regulators might
adopt or approve.

     22.3 If either Party defaults in the payment of any amount due hereunder,
or if either Party violates any other provision of this Agreement, and such
default or violation shall continue for sixty (60) days after written notice
thereof, the other Party may terminate this Agreement and services hereunder by
written notice; provided the other Party has provided the defaulting Party and
the appropriate federal and/or state regulatory bodies with written notice at
least twenty five (25) days' prior to terminating service. Notice shall be
posted by certified mail, return receipt requested. If the defaulting Party
cures the default or violation within the Twenty five (25) day period, the other
Party will not terminate service or this Agreement but shall be entitled to
recover all costs, if any, incurred by it in connection with the default or
violation, including, without limitation, costs incurred to prepare for the
termination of service.

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES ANY
WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE DISCLAIM
THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR
PURPOSE.

24.0 CANCELLATION CHARGES.

     Except as provided in this Agreement or as otherwise provided in any 
applicable Tariff, no cancellation charges shall apply.

25.0 INDEMNIFICATION.

     25.1 Each Party agrees to release, indemnify, defend and hold harmless the
other Party from and against all losses, claims, demands, damages, expenses,
suits or other actions, or any liability whatsoever, including, but not limited
to, costs and attorneys' fees (collectively, a "Loss"), (a) whether suffered,
made, instituted, or asserted by any other party or person, (i) relating to
personal injury to or death of any person, or for loss, damage to, or
destruction of real and/or personal property, whether or not owned by others,
incurred during the term of this Agreement and to the extent proximately caused
by the acts or omissions of the indemnifying Party, regardless of the form of
action, or (ii) arising out of BA's listing of the directory listing information
provided by

                                      48

<PAGE>
 
MFS pursuant to subsection 19.1, or (b) suffered, made, instituted, or asserted
by its own customer(s) against the other Party arising out the other Party's
provision of services to the indemnifying Party under this Agreement.
Notwithstanding the foregoing indemnification, nothing in this such Section 25.
shall affect or limit any claims, remedies, or other actions the indemnifying
Party may have against the indemnified Party under this Agreement, any other
contract, or any applicable Tariff(s), regulations or laws for the indemnified
Party's provision of said services.

     25.2 The indemnification provided herein shall be conditioned upon:

          (a) The indemnified Party shall promptly notify the indemnifying
     Party of any action taken against the indemnified Party relating to the
     indemnification.

          (b) The indemnifying Party shall have sole authority to defend any
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c) In no event shall the indemnifying Party settle or consent to any
     judgment pertaining to any such action without the prior written consent of
     the indemnified Party, which consent shall not be unreasonably withheld.

          (d) The indemnified Party shall, in all cases, assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e) The indemnified Party shall offer the indemnifying Party all
     reasonable cooperation and assistance in the defense of any such action.

      25.3 In addition to its indemnity obligations under subsection 25.1, each
Party shall provide, in its tariffs and contracts with its Customers that relate
to any Telecommunications Service or Network Element provided or contemplated
under this Agreement, that in no case shall such Party or any of its agents,
contractors or others retained by such parties be liable to any Customer or
third party for (i) any Loss relating to or arising out of this Agreement,
whether in contract or tort, that exceeds the amount such Party would have
charged the applicable Customer for the service(s) or function(s) that gave rise
to such Loss, and (ii) any Consequential Damages (as defined in subsection 26.2
below).


26.0  LIMITATION OF LIABILITY.

      26.1 Except as may be provided pursuant to Section 27 below, the liability
of either Party to the other Party for damages arising out of failure to comply
with a direction to install, restore or terminate facilities; or out of
failures, mistakes, omissions, interruptions, delays, errors, or defects
occurring in the course of furnishing any services, arrangements, or facilities
hereunder shall be determined in accordance with the terms of the applicable
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro

                                      49
<PAGE>
 
rata monthly charge for the period in which such failures, mistakes, omissions,
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for
such failures, mistakes, omissions, interruptions, delays, errors or defects.

     26.2 Neither Party shall be liable to the other in connection with the
provision or use of services offered under this Agreement for indirect,
incidental, consequential, reliance or special damages, including (without
limitation) damages for lost profits (collectively, "Consequential Damages"),
regardless of the form of action, whether in contract, warranty, strict
liability, or tort, including, without limitation, negligence of any kind, even
if the other Party has been advised of the possibility of such damages;
provided, that the foregoing shall not limit a Party's obligation under Section
25.

     26.3 The Parties agree that neither Party shall be liable to the customers
of the other Party in connection with its provision of services to the other
Party under this Agreement. Nothing in this Agreement shall be deemed to create
a third party beneficiary relationship between the Party providing the service
and the customers of the Party purchasing the service. In the event of a dispute
involving both Parties with a customer of one Party, both Parties shall assert
the applicability of any limitations on liability to customers that may be
contained in either Party's applicable Tariff(s).


27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

     27.1 CERTAIN DEFINITIONS. When used in this Section 27, the following
terms shall have the meanings indicated:

          27.1.1  "Specified Performance Breach" means the failure by BA to meet
the Performance Criteria for any one of the three Specified Activities for a
period of three (3) consecutive calendar months.

          27.1.2  "Specified Activity" means any of the following activities:

          (a)  the installation by BA of Unbundled Local Loop Elements for MFS
     ("ULL Installation");

          (b)  BA's provision of INP to MFS or

          (c)  repair of out of service problems for MFS ("Out of Service
     Repairs").

          27.1.3  "Performance Criteria" means, with respect to any calendar
month during the term of this Agreement, the performance by BA during such month
of each Specified Activity (except Out-of-Service Repairs) shown in Schedule
27.0, within the time interval shown, in at least eighty percent (80%) of the
covered instances BA shall perform the Out-of-Service Repairs within the
specified time interval in at least seventy percent (70%) of the covered

                                      50
<PAGE>
 
instances. Within one week of each anniversary of the Effective Date, the 
Parties shall jointly review BA's actual network-wide monthly performance 
percentages for Out-of Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual 
percentages for any three consecutive month period and/or the full preceding 
year, up to and including an eighty percent (80%) standard, as the 
Out-of-Service Repairs percentage standard applicable to the following year.

     27.2  PERFORMANCE STANDARDS. BA shall exercise best efforts to meet the 
Performance Criteria for the three Specified Activities. In the event BA fails 
to meet the Performance Criteria at any time during the term of this Agreement, 
MFS shall be entitled to pursue all remedies set forth in the applicable BA 
Tariffs, except as may be agreed to by the Parties. In addition, if BA commits a
Specified Performance Breach during the term of this Agreement, the Parties 
agree to meet immediately to determine whether any liquidated damages provisions
are appropriate as an amendment hereof in light of such Breach and, if so, the 
terms therein; provide, however, that if BA commits a Specified Performance 
Breach during initial nine (9) months of this Agreement, the Parties agree to 
meet at the end of the nine-month period. If the Parties are unable to agree as 
to the appropriateness of the liquidated damages provisions and/or the terms 
therein within ninety (90) days after the date of the first meeting pursuant to 
this subsection, or if no such meeting has occurred within ninety (90) days of 
the end of the nine-month period for reasons other than the mutual agreement of 
the Parties, the Parties agree to submit to arbitration such disagreement and 
request that the arbitrators base their decision on comparable ILEC-CLEC 
interconnection agreements. Unless otherwise agreed to by the Parties, the 
arbitration shall be conducted by a panel of three (3) arbitrators, one to be 
appointed by each Party pursuant to CPR's Non-Administered Arbitration Rules and
subject to the United States Arbitration Act (9 U.S.C (SS) 1-16), to be
conducted in Arlington, Virginia. The Parties agree that the liquidated damages
provisions, if any, finally determined by the arbitral process shall be adopted
as an amendment to this Agreement.

     27.3  LIMITATIONS. In no event shall BA be deemed to have failed to meet 
any of the Performance Criteria if:

           27.3.1   BA's failure to meet or exceed any of the Performance 
Criteria is caused, directly or indirectly, by a Delaying Event. A "Delaying 
Event" means (a) a failure by MFS to perform any of its obligations set forth in
this Agreement (including, without limitation, the Implementation Schedule and 
the Joint Grooming Plan), (b) any delay, act or failure to act by a Customer,
agent, representative, or subcontractor of MFS or (c) any Force Majeure Event. 
If a Delaying Event prevents or delays BA from performing a Specified Activity, 
then such Specified Activity shall be excluded from the calculation of BA's 
compliance with the Performance Criteria, provided BA performs the Specified 
Activity in the course of its normal service cycle once the Delaying Event no 
longer exists; or

           27.3.2   the Parties agree to a time interval with respect to a 
particular order that exceeds the interval set forth in Schedule 27. In such 
event, the time interval for BA's performance of the Specified Activit(ies) set 
forth in the order shall be extended to such later date agreed to by the 
Parties.

                                      51

<PAGE>
 
     27.4 Service Quality Standards. MFS agrees to specific performance
standards associated with quality of service requests as specified in Schedule
27.1. Should MFS fail to meet these service quality standards, during a period
in which BA has failed to meet the Performance Criteria, BA's failure during
such time period shall be excused and not apply toward the calculation of a
Specified Performance Breach.

     27.5 RECORDS. Each Party shall maintain complete and accurate records in
the manner and format agreed to by the Parties, on a monthly basis, of BA's
performance under this Agreement of each Specified Activity and its compliance
with the Performance Criteria during the initial nine-month period. Each Party
shall provide to the other Party such records in a self-reporting format on a
monthly basis. The Parties agree that such records shall be deemed "Proprietary
Information" for purposes of subsection 29.4.


28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

     28.1 Each Party represents and warrants that it is now and will remain in
compliance with all laws, regulations, and orders applicable to the performance
of its obligations hereunder (collectively, "Applicable Laws"). Each Party shall
promptly notify the other Party in writing of any governmental action that
suspends, cancels, withdraws, limits, or otherwise materially affects its
ability to perform its obligations hereunder.

     28.2 The Parties understand and agree that this Agreement will be filed
with the Commission and may thereafter be filed with the FCC. The Parties
covenant and agree that this Agreement is satisfactory to them as an agreement
under Section 251 of the Act. Each Party covenants and agrees to fully support
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek
regulatory relief and otherwise seek redress from each other regarding
performance and implementation of this Agreement.

     28.3 The Parties recognize that the FCC is currently promulgating
regulations implementing the Act, including, without limitation, Sections 251,
252, and 271 thereof (the "FCC Regulations"), that may affect the terms
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties
agree to make only the minimum revisions necessary to eliminate the
inconsistency. Such minimum changes to conform this Agreement to the FCC
Regulations shall not be considered material, and shall not require further
Commission approval (beyond any Commission approval required under Section
252(e) of the Act).

     28.4 In the event any Applicable Law other than the FCC Regulations
requires modification of any material term(s) contained in this Agreement,
either Party may require a renegotiation of the term(s) that require direct
modification as well as of any term(s) that are reasonably affected thereby. If
neither Party requests a renegotiation or if an Applicable Law requires
modification of any non-material term(s), then the Parties agree to make only 
the minimum

                                      52
<PAGE>
 
modifications necessary, and the remaining provisions of this Agreement shall
remain in full force and effect. For purposes of this subsection 28.4 and
without limitation of any other modifications required by Applicable Laws, the
Parties agree that any modification required by Applicable Laws (i) to the two-
tier Reciprocal Call Termination compensation structure for the transport and
termination of Local Traffic described in Exhibit A, or (ii) that affects either
Party's receipt of reciprocal compensation for the transport and termination of
Local Traffic, shall be deemed to be a modification of a material term that
requires immediate good faith renegotiation between the Parties. Until such
renegotiation results in a new agreement or an amendment to this Agreement
between the Parties, the Parties agree that (y) in the case of (i) above, they
will pay each other appropriate transport charges in addition to the usual call
termination charge for Local Traffic that it delivers to the other Party's Local
Serving Wire Center, provided each Party continues to offer the option of
delivering Local Traffic to another IP in the LATA at the usual call termination
charge only, and (z) in the case of (ii) above, the Party whose receipt of
reciprocal compensation is affected shall not be obligated to pay the other
Party reciprocal compensation for the other Party's transport and termination of
the same kind of Local Traffic delivered by the affected Party in excess of what
the affected Party is permitted to receive and retain.


29.0  MISCELLANEOUS.

      29.1  AUTHORIZATION.

            29.1.1  BA is a corporation duly organized, validly existing and in
good standing under the laws of the Commonwealth of Virginia and has full power
and authority to execute and deliver this Agreement and to perform the
obligations hereunder on behalf of BA.

            29.1.2  MFS is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware and has full power and
authority to execute and deliver this Agreement and to perform its obligations
hereunder.

      29.2  INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder
as an independent contractor and nothing herein shall be construed as creating
any other relationship between the Parties. Each Party and each Party's
contractor shall be solely responsible for the withholding or payment of all
applicable federal, state and local income taxes, social security taxes and
other payroll taxes with respect to their employees, as well as any taxes,
contributions or other obligations imposed by applicable state unemployment or
workers' compensation acts. Each Party has sole authority and responsibility to
hire, fire and otherwise control its employees.

      29.3  FORCE MAJEURE. Neither Party shall be responsible for delays or
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in
performance were foreseen or foreseeable as of the date of this Agreement,
including, without limitation: adverse weather conditions, fire, explosion,
power failure, acts of God, war, revolution, civil commotion, or acts of public
enemies; any law, order, regulation, ordinance or requirement of any government
or legal body; or labor unrest, including, without limitation, strikes,
slowdowns, picketing or boycotts; or delays caused by the

                                      53
<PAGE>
 
other Party or by other service or equipment vendors; or any other circumstances
beyond the Party's reasonable control. In such event, the affected Party shall,
upon giving prompt notice to the other Party, be excused from such performance
on a day-to-day basis to the extent of such interferences (and the other Party
shall likewise be excused from performance of its obligations on a day-for-day
basis to the extent such Party's obligations relate to the performance so
interfered with). The affected Party shall use its best efforts to avoid or
remove the cause(s) of non-performance and both Parties shall proceed to perform
with dispatch once the cause(s) are removed or cease.

     29.4 CONFIDENTIALITY.

          29.4.1  All information, including but not limited to specification,
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches,
models, samples, tools, technical information, data, employee records, maps,
financial reports, and market data, (i) furnished by one Party to the other
Party dealing with customer specific, facility specific, or usage specific
information, other than customer information communicated for the purpose of
publication or directory database inclusion, or (ii) in written, graphic,
electromagnetic, or other tangible form and marked at the time of delivery as
"Confidential" or "Proprietary," or (iii) communicated orally and declared to
the receiving Party at the time of delivery, or by written notice given to the
receiving Party within ten (10) days after delivery, to be "Confidential" or
"Proprietary" (collectively referred to as "Proprietary Information"), shall
remain the property of the disclosing Party.

          29.4.2  Each Party shall keep all of the other Party's Proprietary
Information confidential and shall use the other Party's Proprietary Information
only for performing the covenants contained in this Agreement. Neither Party
shall use the other Party's Proprietary Information for any other purpose except
upon such terms and conditions as may be agreed upon between the Parties in
writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality
and non-use set forth in this Agreement do not apply to such Proprietary
Information that:

          (a) was, at the time of receipt, already known to the receiving Party
     free of any obligation to keep it confidential as evidenced by written
     records prepared prior to delivery by the disclosing Party; or

          (b) is or becomes publicly known through no wrongful act of the
     receiving Party; or

          (c) is rightfully received from a third person having no direct or
     indirect secrecy or confidentiality obligation to the disclosing Party with
     respect to such information; or

          (d) is independently developed by an employee, agent, or contractor of
     the receiving Party that is not involved in any manner with the provision
     of services pursuant to this Agreement and does not have any direct or
     indirect access to the Proprietary Information; or

                                      54
<PAGE>
 
          (e)     is approved for release by written authorization of the 
     disclosing Party; or

          (f)     is required to be made public by the receiving Party pursuant
     to applicable law or regulation, provided that the receiving Party shall
     give sufficient notice of the requirement to the disclosing Party to enable
     the disclosing Party to seek protective orders.

          29.4.4  Upon request by the disclosing Party, the receiving Party 
shall return all tangible copies of Proprietary Information, whether written,
graphic or otherwise, except that the receiving Party may retain one copy for
archival purposes only.

          29.4.5  Notwithstanding any other provision of this Agreement, the 
provisions of this subsection 29.4 shall apply to all Proprietary Information
furnished by either Party to the other in furtherance of the purpose of this
Agreement, even if furnished before the Effective Date.

     29.5 CHOICE OF LAW.  The construction, interpretation and performance of 
this Agreement shall be governed by and construed in accordance with the laws of
the state in which this Agreement is to be performed, except for its conflicts
of laws provisions.  In addition, insofar as and to the extent federal law may
apply, federal law will control.

     29.6 TAXES

          29.6.1. In General. With respect to any purchase hereunder of 
                  ----------
services, facilities or arrangements, if any federal, state or local tax, fee,
surcharge or other tax-like charge (a "Tax") is required or permitted by
Applicable Law (as defined in subsection 28.1) to be collected from the
purchasing Party by the providing Party, then (i) the providing Party shall
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

          29.6.2. Taxes Imposed on the Providing Party. With respect to any 
                  ------------------------------------  
purchase hereunder of services, facilities or arrangements, if any federal,
state or local Tax is imposed by Applicable Law on the receipts of the providing
Party, which law permits the providing Party to exclude certain receipts 
received from sales for resale to a public utility, distributor, telephone 
company ("Telecommunications Company"), such exclusion being based solely on the
fact that the purchasing Party is also subject to a tax based upon receipts
("Receipts Tax"), then the purchasing Party (i) shall provide the providing 
Party with notice in writing in accordance with subsection 29.6.6 of this 
Agreement of its intent to pay the Receipts Tax and (ii) shall timely pay the
Receipts Tax to the applicable tax authority.
 
          29.6.2. Taxes Imposed on Customers. With respect to any purchase 
                  --------------------------  
hereunder of services, facilities or arrangements that are resold to a third 
party, if any federal, state or local Tax is imposed by Applicable Law on the 
subscriber, end-user, Customer or ultimate consumer ("Subscriber") in 
connection with any such purchase, which a Telecommunications Company is

                                      55 

 

<PAGE>
 
required to impose and/or collect from a Subscriber, then the purchasing Party 
(i) shall be required to impose and/or collect such Tax from the Subscriber and 
(ii) shall timely remit such Tax to the applicable taxing authority.

               29.6.4 Liability for Uncollected Tax, Interest and Penalty. If
                      ---------------------------------------------------
the providing Party has not received an exemption certificate and fails to
collect any Tax as required by subsection 29.6.1, then, as between the providing
Party and the purchasing Party, (i) the purchasing Party shall remain liable for
such uncollected Tax and (ii) the providing Party shall be liable for any
interest assessed thereon and any penalty assessed with respect to such
uncollected Tax by such authority. If the providing Party properly bills the
purchasing Party for any Tax but the purchasing Party fails to remit such Tax to
the providing Party as required by subsection 29.6.1, then, as between the
providing Party and the purchasing Party, the purchasing Party shall be liable
for such uncollected Tax and any interest assessed thereon, as well as any
penalty assessed with respect to such uncollected Tax by the applicable taxing
authority. If the providing Party does not collect any Tax as required by
subsection 29.6.1 because the purchasing Party has provided such providing Party
with an exemption certificate that is later found to be inadequate by a taxing
authority, then, as between the providing Party and the purchasing Party, the
purchasing Party shall be liable for such uncollected Tax and any interest
assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. If the purchasing Party
fails to pay the Receipts Tax as required by subsection 29.6.2, then, as between
the providing Party and the purchasing Party, (x) the providing Party shall be
liable for any tax imposed on its receipts and (y) the purchasing Party shall be
liable for any interest assessed thereon and any penalty assessed upon the
providing Party with respect to such Tax by such authority. If the purchasing
party fails to impose and/or collect any Tax from Subscribers as required by
subsection 29.6.3, then, as between the providing Party and the purchasing
Party, the purchasing Party shall remain liable for such uncollected Tax and any
interest assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. With respect to any Tax that
the purchasing Party has agreed to pay, or is required to impose on and/or
collect from Subscribers, the purchasing Party agrees to indemnify and hold the
providing Party harmless on an after-tax basis for any costs incurred by the
providing Party as a result of actions taken by the applicable taxing authority
to recover the Tax from the providing Party due to the failure of the purchasing
Party to timely pay, or collect and timely remit, such Tax to such authority. In
the event either Party is audited by a taxing authority, the other Party agrees
to cooperate fully with the Party being audited in order to respond to any audit
inquiries in a proper and timely manner so that the audit and/or any resulting
controversy may be resolved expeditiously.

               29.6.5. Tax Exemptions and Exemption Certificates. If Applicable
                       -----------------------------------------  
Law clearly exempts a purchase hereunder from a Tax, and if such Law also
provides an exemption procedure, such as an exemption-certificate requirement,
then, if the purchasing Party complies with such procedure, the providing Party
shall not collect such Tax during the effective period of such exemption. Such
exemption shall be effective upon receipt of the exemption certificate or
affidavit in accordance with the terms set forth in subsection 29.6.6. If
Applicable Law clearly exempts a purchase hereunder from a Tax, but does not
also provide an exemption procedure, then the providing Party shall not collect
such Tax if the purchasing Party (i) furnishes the

                                      56
<PAGE>
 
providing Party with a letter signed by an officer requesting such an exemption 
and citing the provision in the Law which clearly allows such exemption and 
(ii) supplies the providing Party with an indemnification agreement, reasonably 
acceptable to the providing Party (e.g., an agreement commonly used in the 
                                   - -
industry), which holds the providing Party harmless on an after-tax basis with 
respect to its forbearing to collect such Tax.

          29.6.6. Notices for Purposes of this Subsection 29.6. All notices, 
                  ---------------------------------------------
affidavits, exemption-certificates or other communications required or permitted
to be given by either Party to the other, for purposes of this subsection 29.6,
shall be made in writing and shall be delivered in person or sent by certified
mail, return receipt requested, or registered mail, or a courier service
providing proof of service, and sent to the addressees set forth in subsection
29.10 as well as to the following:

     To Bell Atlantic:        Tax Administration 
                              Bell Atlantic Network Services, Inc.
                              1717 Arch Street
                              30th Floor 
                              Philadelphia, PA 19103

     To MFS:                  Corporate Tax Department
                              MFS Communications Company, Inc.
                              11808 Miracle Hills Drive
                              Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addressees
by giving notice is accordance with the terms of this subsection 29.6. Any 
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT. Neither Party shall assign this Agreement nor any of its 
rights or obligations hereunder without the prior written consent of the other
Party, which consent shall not be unreasonably withheld. Any assignment or
delegation in violation of this subsection 29.7 shall be void and ineffective
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS.

          29.8.1 Except may otherwise be provided in this Agreement, each Party 
shall submit on a monthly basis an itemized statement of charges incurred by 
the other Party during the preceding month(s) for services rendered hereunder.
Payment of billed amounts under this Agreement, whether billed on a monthly
basis or as otherwise provided herein, shall be due, in immediately available
U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2 Although it is the intent of both Parties to submit timely and 
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or
a waiver of the right to payment of the incurred charges, by the billing Party
under this Agreement, and the billed Party shall not be entitled to

                                      57

<PAGE>
 
dispute the billing Party' statement(s) based on such Party's failure to submit 
them in a timely fashion.

           29.8.3   If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60) days 
of its receipt of the invoice containing such disputed amount give notice to the
Billing Party of the amounts it disputes ("Disputed Amounts") and include in 
such notice the specific details and reasons for disputing each item. The 
Non-Paying Party shall pay when due (i) all undisputed amounts to the Billing 
Party and (ii) all Disputed Amounts into an interest bearing escrow account with
a third party escrow agent mutually agreed upon by the Parties.

           29.8.4   If the Parties are unable to resolve the issues related to 
the Disputed Amounts in the normal course of business within ninety (90) days 
after delivery to the Billing Party of notice of the Disputed Amounts, each of 
the Parties shall appoint a designated representative that has authority to 
settle the dispute and that is at a higher level of management than the persons 
with direct responsibility for administration of this Agreement. The designated 
representatives shall meet as often as they reasonably deem necessary in order 
to discuss the dispute and negotiate in good faith in an effort to resolve such 
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant 
information made by one Party to the other Party shall be honored.

           29.8.5   If the Parties are unable to resolve issues related to the 
Disputed Amounts within forty-five (45) days after the Parties' appointment of 
designated representatives pursuant to subsection 29.8.4, then either Party may 
file a complaint with the Commission to resolve such issues or proceed with any 
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus 
applicable late fees, to be paid to either Party.

           29.8.6   The Parties agree that all negotiations pursuant to this 
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state 
rules of evidence.

           29.8.7   Any undisputed amounts not paid when due shall accrue
interest from the date such amounts were due at the lesser of (i) one and one-
half percent (1-1/2%) per month or (ii) the highest rate of interest that may be
charged under applicable law.

     29.9  DISPUTE RESOLUTION. Any dispute between the Parties regarding the 
interpretation of enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial 
forum of component jurisdiction.

                                      58

<PAGE>
 
     29.10   NOTICES. Notices given by one Party to the other Party under this 
Agreement shall be in writing and shall be (a) delivered personally, (b) 
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by 
telecopy to the following addresses of the Parties:

             To MFS:

             MFS Intelenet of Virginia, Inc.
             33 Whitehall St.
             15th Floor
             New York, NY 10004
             Attn: Director, Regulatory Affairs - Eastern Region
             Facsimile: 212/843-3060

             To Bell Atlantic:

             Director - Interconnection Services
             Bell Atlantic Network Services, Inc.
             1320 N. Courthouse Road
             9th Floor
             Arlington, VA 22201
             Facsimile: 703/974-2183

             with a copy to:

             Vice President and General Counsel
             Bell Atlantic - Virginia, Inc.
             600 East Main Street 
             24th Floor
             Richmond, VA 23261
             Facsimile: (804) 772-2143

or to such other address as either Party shall designate by proper notice. 
Notices will be deemed given as of the earlier of (i) the date of actual receipt
(ii) the next business day when notice is sent via express mail or personal
delivery, (iii) three (3) days after mailing in the case of first class or
certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of telecopy.

     29.11   SECTION 252(I) OBLIGATIONS.

             29.11.1 If, at any time during the term of this Agreement, either 
Party enters into an agreement to provide an integrated package of services or 
arrangements substantially similar to that described herein to another CLEC (in 
the case of BA), or another incumbent LEC (in the case of MFS), operating within
the same state to which this Agreement applies, on terms significantly

                                      59
<PAGE>
 
different than those available under this Agreement (the "Other Agreement"),
then the other Party may opt to adopt, on a prospective basis only, the rates,
terms, and conditions contained in the Other Agreement (i) in its entirety, or
(ii) that relate directly to any of the following individual services, Network
Elements, or arrangements, for its own reciprocal arrangements with the first 
Party, including, without limitation, any term or volume commitments or network
architecture configurations:

          (a)   Unbundled Loop Elements - Section 251(c)(3) of the Act (Section
     11 of this Agreement); or

          (b)   Collocation - Section 251(c)(6) of the Act (Section 13 of this
     Agreement); or

          (c)   Number Portability - Section 251(b)(2) of the Act (Section 14 of
     this Agreement); or           

          (d)   Access to Rights of Way - Section 251(b)(4) of the Act (Section
     16 of this Agreement).

          (e)   transiting arrangements.

          29.11.2  To the extent the exercise of the foregoing options requires
a rearrangement of facilities by the providing Party, the opting Party shall be
liable for the non-recurring charges associated therewith.

          29.11.3  The Party electing to exercise such option shall do so by 
delivering written notice to the first Party. Upon receipt of said notice by the
first Party, the Parties shall amend this Agreement to provide the same rates, 
terms and conditions to the notifying Party for the remaining term of this 
Agreement; provided, however, that the Party exercising its option under this
subsection 29.11 must continue to provide the same services or arrangements to
the first Party as required by this Agreement, subject either to the rates,
terms, and conditions applicable to the first Party in its agreement with the
third party or to the rates, terms, and conditions of this Agreement, whichever
is more favorable to the first Party in its sole determination.

          29.11.4  BA represents and warrants that, as of the date of this 
Agreement, it has not entered into any comparable Interconnection agreement with
any other CLEC in BA's service territory that is significantly more favorable
than the terms contained herein. BA makes no warranty or representation with
respect to its Interconnection arrangements with its affiliates or ITCs.

     29.12  JOINT WORK PRODUCT.  This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and 
shall be fairly interpreted in accordance with its terms and, in the event of 
any ambiguities, no inferences shall be drawn against either Party.

                                      60
<PAGE>
 
     29.13  NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. This Agreement 
is for the sole benefit of the Parties and their permitted assigns, and nothing 
herein express or implied shall create or be construed to create any third-party
beneficiary rights hereunder. Except for provisions herein expressly authorizing
a Party to act for another, nothing in this Agreement shall constitute a Party
as a legal representative or agent of the other Party, not shall a Party have
the right or authority to assume, create or incur any liability or any
obligation of any kind, express or implied, against or in the name or on behalf
of the other Party unless otherwise expressly permitted by such other Party.
Except as otherwise expressly provided in this Agreement, no Party undertakes to
perform any obligation of the other Party, whether regulatory or contractual, or
to assume any responsibility for the management of the other Party's business.

     29.14  NO LICENSE.

            29.14.1  Nothing in this Agreement shall be construed as the grant 
of a license, either express or implied, with respect to any patent, copyright, 
trademark, trade name, trade secret or any other proprietary or intellectual 
property now or hereafter owned, controlled or licensable by either Party. 
Neither Party may use any patent, copyrightable materials, trademark, trade 
name, trade secret or other intellectual property right of the other Party 
except in accordance with the terms of a separate license agreement between the 
Parties granting such rights.

            29.14.2  Neither Party shall have any obligation to defend, 
indemnify or hold harmless, or acquire any license or right for the benefit of, 
or owe any other obligation or have any liability to, the other Party or its 
customers based on or arising from any claim, demand, or proceeding by any third
party alleging or asserting that the use of any circuit, apparatus, or system, 
or the use of any software, or the performance of any service or method, or the 
provision of any facilities by either Party under this Agreement, alone or in 
combination with that of the other Party, constitutes direct, vicarious or 
contributory infringement or inducement to infringe, misuse or misappropriation 
of any patent, copyright, trademark, trade secret, or any other proprietary or 
intellectual property right of any Party or third party. Each Party, however, 
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

            29.14.3  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE 
PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, ANY 
WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S 
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT 
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR 
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15  TECHNOLOGY UPGRADES. Nothing in this Agreement shall limit BA's 
ability to upgrade its network through the incorporation of new equipment, new 
software or otherwise. BA shall provide MFS written notice at least ninety (90) 
days prior to the incorporation of any such upgrades in BA's network that will 
materially affect MFS's service. MFS shall be solely responsible for the cost 
and effort of accommodating such changes in its own network.

                                      61

<PAGE>
 
     29.16  SURVIVAL. The Parties' obligations under this Agreement which by 
their nature are intended to continue beyond the termination or expiration of 
this Agreement shall survive the termination or expiration of this Agreement.

     29.17  ENTIRE AGREEMENT. The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other documents or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with respect to the subject matter 
hereof, superseding all prior understandings, proposals and other 
communications, oral or written. Neither Party shall be bound by any preprinted 
terms additional to or different from those in this Agreement that may appear 
subsequently in the other Party's form documents, purchase orders, quotations, 
acknowledgments, invoices or other communications.

     29.18  COUNTERPARTS. This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19  MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No modification, 
amendment, supplement to, or waiver of the Agreement or any of its provisions 
shall be effective and binding upon the Parties unless it is made in writing and
duly signed by the Parties. A failure or delay of either Party to enforce any of
the provisions hereof, to exercise any option which is herein provided, or to 
require performance of any of the provisions hereof shall in no way be construed
to be a waiver of such provisions or options.

     29.20  SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and inure
to the benefit of the Parties and their respective legal successors and 
permitted assigns.

     29.21  PUBLICITY. Neither Party shall use the name of the other Party in 
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      62

<PAGE>
 
          IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to 
be executed as of this 16th day of July, 1996.


MFS INTELENET OF                             BELL ATLANTIC - 
VIRGINIA, INC.                               VIRGINIA, INC.

By: /s/ Alex J. Harris                       By: /s/ H.R. Stallard
   --------------------------------------       -------------------------------
Printed: ALEX J. HARRIS                      Printed: H.R. STALLARD
        ---------------------------------            --------------------------
Title: Vice President Regulatory Affairs     Title: Pres. / CEO - BA - VA
      -----------------------------------          ----------------------------

                                      63

<PAGE>
 
SCHEDULE 1.0

CERTAIN TERMS AS DEFINED IN THE ACT, AS OF JULY 16, 1996

     "Dialing Parity" means that a person that is not an affiliate of a local 
exchange carrier is able to provide Telecommunications Services in such a manner
that Customers have the ability to route automatically, without the use of any 
access code, their Telecommunications to the Telecommunications Services 
provider of the customer's designation from among two (2) or more 
Telecommunications Services providers (including such LEC).

     "Exchange Access" means the offering of access to Telephone Exchange 
Services or facilities for the purpose of the origination or termination of
Telephone Toll Services.

     "InterLATA" means Telecommunications between a point located in a local 
access and transport area and a point located outside such area.

     "Local Access and Transport Area" or "LATA" means a contiguous geographic 
area: (a) established before the date of enactment of the Act by a Bell 
operating company such that no Exchange Area includes points within more than 
one (1) metropolitan statistical area, consolidated metropolitan statistical 
area, or State, except as expressly permitted under the AT&T Consent Decree; or 
(b) established or modified by a Bell operating company after such date of 
enactment and approved by the FCC.

     "Local Exchange Carrier" means any person that is engaged in the provision 
of Telephone Exchange Service or Exchange Access.  Such term does not include a 
person insofar as such person is engaged in the provision of a commercial mobile
service under Section 332(c) of the Act, except to the extent that the FCC finds
that such service should be included in the definition of such term. 

     "Network Element" means a facility or equipment used in the provision of
a Telecommunications Service.  Such term also includes features, functions, and 
capabilities that are provided by means of such facility or equipment, including
subscriber numbers, databases, signaling systems, and information sufficient for
billing and collection or used in the transmission, routing, or other provision 
of a Telecommunications Service.

     "Number Portability" means the ability of end users of telecommunications 
services to retain, at the same location, existing telecommunications numbers 
without impairment of quality, reliability, or convenience when switching from 
one telecommunications carrier to another.

     "Telecommunications" means the transmission, between or among points 
specified by the user, of information of the user's choosing, without change in 
the form or content of the information as sent and received.
<PAGE>
 
     "Telecommunications Carrier" means any provider of Telecommunications 
Services, except that such term does not include aggregators of 
Telecommunications Services (as defined in Section 226 of the Communications 
Act).

     "Telecommunications Service" means the offering of Telecommunications for a
fee directly to the public, or to such classes of users as to be effectively
available directly to the public, regardless of the facilities used.

     "Telephone Exchange Service" means (a) service within a telephone exchange 
or within a connected system of telephone exchanges within the same exchange 
area operated to furnish subscribers intercommunicating service of the character
ordinarily furnished by a single exchange, and which is covered by the exchange 
service charge, or (b) comparable service provided through a system of switches,
transmission equipment, or other facilities (or combination thereof) by which a 
subscriber can originate and terminate a telecommunications service.
     
     "Telephone Toll Service" means telephone service between stations in 
different exchange areas for which there is made a separate charge not included 
in contracts with subscribers for exchange service.
<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA


     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
than the listed Dates.

<TABLE> 
<CAPTION> 
======================================================================================================
LATA IN VIRGINIA         MILESTONE                                              DATE
- ------------------------------------------------------------------------------------------------------
<S>                      <C>                                                    <C> 
LATA 236                 LATA Start Date ("SD")                                 Effective Date
                         -----------------------------------------------------------------------------
                         SS7 Certification, Collocation, and NXX(s)             SD plus 15 days
                         Applied For 
                         -----------------------------------------------------------------------------
                         Parties Agree on Initial Network Design                SD plus 30 days
                         -----------------------------------------------------------------------------
                         Valid Access Service Request(s) ("ASRs") and           SD plus 45 days
                         Routing Information Received by BA
                         -----------------------------------------------------------------------------
                         Collocation Arrangements Complete for Trunk            SD plus 135 days
                         Interconnection and IDLC for ULLs
                         -----------------------------------------------------------------------------
                         All Trunks Tested and Turned Up; SS7 Certification     SD plus 155 days
                         Achieved; /1/ VG ULL Capability Available
                         ----------------------------------------------------------------------------- 
                         Call-through Testing Completed;                        SD plus 180 days   
                         "Interconnection Activation Date"
- ------------------------------------------------------------------------------------------------------
</TABLE> 

     Failure of a Party or the Parties to meet an earlier Milestone Date shall 
not relieve either Party of the responsibility to make its best efforts to meet 
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that, 
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when
MFS has an effective Tariff for business Telephone Exchange Service in the 
Commonwealth of Virginia and has a significant number of Telephone Exchange 
Service Customer lines in service for business Telephone Exchange Service
Customers in that LATA in the Commonwealth of Virginia that are not affiliates
or employees of either BA or MFS, and (ii) residential Telephone Exchange
Service shall be considered "fully operational" in a LATA in the Commonwealth of
Virginia when MFS has an effective Tariff for residential Telephone Exchange
Service in the Commonwealth of Virginia and has a significant number of
Telephone Exchange Service Customer lines in service for residential Telephone
Exchange Service Customers in that LATA in the Commonwealth of Virginia that are
not affiliates or employees of either BA or MFS.


______________________________
/1/   SS7 certification scheduling depends on actual schedule availability at
time of request.

                                       1
<PAGE>
 
SCHEDULE 4

INTERCONNECTION POINTS IN LATA


                                   LATA 236
                                   --------

M-IP:  Reston Switch
       12379 Sunrise Valley Dr.
       Reston, VA

BA-IP  Arlington Tandem
       1025 N. Irving Street
       Arlington, VA
<PAGE>
 

                     SCHEDULE 4.2 - PHYSICAL ARCHITECTURE
                                
                                [ILLUSTRATIVE]




                             [GRAPH APPEARS HERE]


<PAGE>
 
                     SCHEDULE 4.3 - INITIAL ARCHITECTURE 

                                [ILLUSTRATIVE]


     Bell Atlantic Leases MFS-owned Facilities for Delivery of BA Traffic 
     
                           [FLOOR PLAN APPEARS HERE]
               
               MFS-owned Facilities for Delivery of MFS Traffic
<PAGE>
 
SCHEDULE 4.5

INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC

     Each Party shall provide the other Party with Interconnection to its 
network at the following points for transmission, routing and termination. Each 
Party shall make available at its Interconnection Points facilities to route the
traffic it receives to the appropriate final destination. Interconnection at a 
BA-IP that is a Local Serving Wire Center provides access to all of the 
Interconnection Points identified below (except for paragraphs 8 through 11), 
via facilities appropriate for the traffic types and destinations identified 
below. Compensation for such facilities will be as set forth in Exhibit A or as 
provided elsewhere herein. 
 
     1.   For the termination of Local Traffic or Toll Traffic originated by 
one Party's Customer and terminated to the other Party's Customer, at the points
set forth in subsections 4.2 and/or 4.3 of the main body of the Agreement.

     2.   For the termination of Meet Point Billing Traffic Traffic from an IXC 
to:

          (a)   MFS, at the M-IP in LATA in which the Traffic is to terminate.
     
          (b)   BA, at the BA-IP in LATA in which the Traffic is to terminate.
     
     3.   For the termination of Transit Traffic from an ITC, wireless carrier,
or other CLEC to:

          (a)   MFS, at the M-IP in which the Traffic is to terminate.

          (b)   BA, at the BA-IP in LATA in which the Traffic is to terminate.

     4.   For 911/E911 traffic originated on MFS's network, at the PSAP in areas
where only Basic 911 service is available, or at the BA 911 Tandem Office 
serving the area in which the MFS Customer is located, in accordance with
applicable state laws and regulations and PSAP requirements. 

     5.   For Directory Assistance (411 or NPA-555-1212) traffic, at the 
applicable BA Local Serving Wire Center or the BA operator services Tandem 
Office subtended by such Local Serving Wire Center.

     6.   For Operator Services (call completion) traffic, at the applicable BA
Local Serving Wire Center or the BA operator services Tandem Office subtended by
such Local Serving Wire Center.

     7.   For LSV/VCI traffic, at the terminating Party's Local Serving Wire
Center or operator services Tandem Office subtended by such Local Wire Center.
 
                                      1  
 




<PAGE>
 
     8.   For SS7 signaling originated by:

          (a)  MFS, at mutally agreed-upon Signaling Point of Interconnection(s)
("SPOI") in the LATA in which the Local or Toll Traffic originates, over CCSAC
links provisioned in accordance with Bellcore GR-905 and Bell Atlantic 
Supplement Common Channel Signaling Network Interface Specification (BA_905).

          (b)  BA, at mutually agreed-upon SPOIs in the LATA in which the Local 
or Toll Traffic originates, over a CCSAC links provisioned in accordance with 
Bellcore GR-905 and BA-905.

Alternatively, either Party may elect to interconnect for SS7 signaling through 
a commercial SS7 hub provider.

     9.   For 800/888 database inquiry traffic, at any BA Signaling Transfer 
Point in the LATA in which the originating MFS Wire Center is located, over a 
CCSAC link.  Alternatively, MFS may elect to interconnect through a commercial 
SS7 hub provider.

     10.  For Line Information Database ("LIDB") inquiry traffic, at any BA
Signaling Transfer Point in the LATA in which the LIDB is located, over a CCSAC
link. Alternatively, MFS may elect to interconnect through a commercial SS7 hub
provider.

     11.  For any other type of traffic, at reasonable points to be agreed upon 
by the Parties, based on the network architecture of the terminating Party's
network.

                                       2
<PAGE>
 
SCHEDULE 6.3

RATE ELEMENTS UNDER MEET POINT BILLING

INTERSTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS
- --------------------------------------------------------------------

<TABLE> 
<CAPTION> 
<S>                                     <C>
RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/               
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query
</TABLE> 

INTRASTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS/1/
- -----------------------------------------------------------------------

<TABLE> 
<CAPTION> 
<S>                                     <C> 
RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/               
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query
</TABLE> 

____________________
/1/  Pending approval of the BA intrastate local transport restructure tariff, 
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

                                       1

<PAGE>
 
SCHEDULE 27.0

PERFORMANCE INTERVAL DATES FOR SPECIFIED ACTIVITIES


- --------------------------------------------------------------------------------
            SPECIFIED ACTIVITY                    PERFORMANCE INTERVAL DATE/2/
 (i)  UNBUNDLED LOCAL LOOP INSTALLATION/1/     
      ---------------------------------
- --------------------------------------------------------------------------------
 1-10 Loops per service order                     6 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 11-20 Loops per service order                    10 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 21 + Loops per service order                     To be negotiated on order-by-
                                                  order basis
- --------------------------------------------------------------------------------
 (ii) INTERIM NUMBER PORTABILITY INSTALLATION     
      ---------------------------------------
- --------------------------------------------------------------------------------
 1-10 Numbers per service order                   6 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 11-20 Numbers per service order                  10 days from BA's receipt of 
                                                  valid service order
- --------------------------------------------------------------------------------
 21 + Numbers per service order                   To be negotiated on 
                                                  order-by-order basis
- --------------------------------------------------------------------------------
 (iii) OUT-OF-SERVICE REPAIRS                     Less than 24 hours from BA's
       ----------------------
                                                  receipt of notification of 
                                                  out-of-service condition
- --------------------------------------------------------------------------------



__________________________

/1/  The Unbundled Loop Installation intervals set forth in this Schedule 27.0 
apply only to ULLs offered by BA as of the date of this Agreement. Installation 
intervals for new ULLs will be developed by the Parties as such ULLs become 
available.
/2/  Unless otherwise agreed to by the Parties, in which case the Performance 
Interval Date shall be extended until the agreed-upon date. Notwithstanding the 
Performance Interval Dates contained in this Schedule 27.0, under no
circumstances will BA be obligated to extend installation, provision,or repair
intervals to MFS that are more favourable than BA extends to its own customers
for comparable services.

                                       2
<PAGE>
 
SCHEDULE 27.1

MFS SERVICE QUALITY STANDARDS


1.0   UNBUNDLED LOCAL LOOP INSTALLATION ORDERS

1.1   All order information submitted by MFS is valid (e.g. street address, 
floor/unit number, cable pair assignment, etc.).

1.2   Customer (end user) is available at appointed time and day.


2.0   "LIVE" CUTOVER UNBUNDLED LOCAL LOOP INSTALLATION ORDERS (PURSUANT TO 
SECTION 11.6)

2.1   Accurate account and end user information submitted on service request.

2.2   Accurate tie cable and pair assignment provided by MFS on service request.

                                       3

<PAGE>
 
                                                                       EXHIBIT A

                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.


                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   ---------------------------------------- 


A.   BA SERVICES, FACILITIES, AND ARRANGEMENTS:

- --------------------------------------------------------------------------------
     BA SERVICE                NON-RECURRING                 RECURRING
     ----------                -------------                 ---------
- --------------------------------------------------------------------------------
1.a. Entrance facilities,      Per interstate [BA FCC #1 sec. 6.9.1.] and 
     and transport, as         (proposed) intrastate [BA-VA SCC 217 sec. 6.8.2] 
     appropriate, for          access tariffs for Feature Group D service/2/
     Interconnection at 
     BA End Office, Tandem
     Office, Serving Wire
     Center, or other Point
     of Interconnection
                               Illustrative:     

                                Interstate non-recurring: $1, plus $1 switched
                               access connection charge per trunk; DS-1 entrance
                               facility $210-212/mo.
          
                                Intrastate nonrecurring: $895 for first DS-1, 
                               $280 for additional, plus $25 switched access 
                               connection charge per trunk; DS-1 entrance
                               facility $270/mo.
- --------------------------------------------------------------------------------
1.b. Collocation and related   Per interstate [BA FCC 1 sec. 19] and intrastate 
     services for              access tariffs/3/
     Interconnection at BA 
     End Office, Tandem 
     Office, or Serving Wire
     Center
- --------------------------------------------------------------------------------



/1/    Rates listed herein for services, facilities, or arrangements that are
marked with an asterisk (*) are fixed pursuant to section 20 of the Agreement
for the initial term of the Agreement, as set forth in Section 22 of the
Agreement. Rates for services, facilities, or arrangements that are not marked
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.

/2/    Pending approval of the BA intrastate local transport restructure tariff,
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

/3/    Pending approval of the BA intrastate collocation tariff to be filed no 
later December 31, 1996, all collocation services shall be charged at rates 
found in BA FCC 1 sec. 19.

                                       1






<PAGE>
 
- --------------------------------------------------------------------------------
      BA SERVICE                      NON-RECURRING         RECURRING
      ----------                      -------------         ---------          
- --------------------------------------------------------------------------------
1.C   Tandem transit arrangements     Per tariffs cited in
      (for Interconnection between    sections 1.a. and     Per interstate [BA
      MFS and carriers other than     1.b. above, as        FCC 1 sec. 6.9.1.B]
      BA)                             applicable; separate  and (proposed)
                                      trunks required for   intrastate [BA-VA
                                      IXC subtending        SCC 217 sec. 
                                      trunks/4/             6.8.2.B] for tandem
                                                            switching and tandem
                                                            switched transport,
                                                            as applicable/5/

                                                            
                                                            Illustrative:
                    
                                                             Interstate,
                                                            (proposed)
                                                            intrastate tandem
                                                            switching $.000999/
                                                            mou, tandem switched
                                                            transport $.000195/
                                                            mou plus $.000045/
                                                            mou/mile
- --------------------------------------------------------------------------------
1.d.  911 Interconnection             Per tariffs cited in 1.a., 1.b., and 1.c.
                                      above, as applicable, for entrance
                                      facility plus applicable transport, or
                                      Collocation Arrangement at 911 tandem
- --------------------------------------------------------------------------------



/4/  See note 2 above.

/5/  See note 2 above.  
 
                                       2
 
   
                                                           
<PAGE>
 
- --------------------------------------------------------------------------------
       BA SERVICE                  NON-RECURRING            RECURRING
       ----------                  -------------            ---------
- --------------------------------------------------------------------------------
 1.e.  Directory assistance        Intrastate per           Intrastate per
       Interconnection             (proposed) BA-VA         (proposed) BA-VA
                                   SCC 217 sec. 9.6.B       SCC 217 sec. 9.6.B;
                                   (transport)/6/
                                                            Illustrative:

                                                              Per call rate
                                                            $.000092 fixed,
                                                            $.000021 per mile,
                                                            $.000462 tandem
                                                            switching, $.003705
                                                            interconnection/7/

                                   Interstate per BA        Interstate per BA   
                                   FCC 1 sec. 9.6.B         FCC 1 sec. 9.6.B

                                                            Illustrative:

                                                              Per call rate
                                                            $.000082 fixed,
                                                            $.000019 per mile,
                                                            $.000353 tandem
                                                            switching, $.002311
                                                            interconnection
- --------------------------------------------------------------------------------
 1.f.  Operator services (call     Per separate contract
       completion) Interconnection   
- --------------------------------------------------------------------------------
 2.    Unbundled elements          Available as listed herein and in interstate
                                   and intrastate tariffs, and pursuant to 
                                   Section 11. of the Agreement
- --------------------------------------------------------------------------------
 3.    Poles, ducts, conduits,     Per contract rates pursuant to 47 U.S.C. sec.
       ROW                         224

                                   Illustrative:

                                     Duct (Northern Virginia) $4.50/ft/yr.

                                     Pole $4.46/attachment/yr.
- --------------------------------------------------------------------------------

/6/    See note 2 above.

/7/    See note 2 above.

                                       3

<PAGE>
 
<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------
       BA SERVICE                            NON-RECURRING                 RECURRING
       ----------                            -------------                 ---------
- -----------------------------------------------------------------------------------------------------
<S>                                          <C>                           <C> 
4.a.   Local loop transmission*              Permanent rates to be         Permanent rates to be 
                                             determined by                 determined by
        Unbundled Local Loop Element         appropriate arbitral          appropriate arbitral 
                                             body. Interim rates           body. Interim rates   
        Cross Connection to POTS loop        will apply until the          will apply until the  
                                             permanent rates are           permanent rates are   
                                             determined./8/                determined./9/        
                                                                                                 


- -----------------------------------------------------------------------------------------------------
 4.b.  Special construction charges          As applicable per BA-VA SCC 203 sec. 2
- -----------------------------------------------------------------------------------------------------
 4.c   Central office technician charges     Per interstate [BA FCC 1 sec. 13.2 or sec.
       (during normal working hours)         19.5] tariff.

- -----------------------------------------------------------------------------------------------------
 5.a.  Trunk Side local transport

        DS-1 transport                       Per interstate [BA FCC 1 sec. 6.9.1.C] and (proposed)
                                             intrastate [BA-VA SCC 217 sec. 6.8.2.C] tariffs/10/


                                             Illustrative recurring:

                                              Interstate $60/mo. fixed, $17.70/mile/mo.

                                              Intrastate $75/mo. fixed, $30/mile/mo.
- -----------------------------------------------------------------------------------------------------
 5.b.   DS-3 transport                       Tariff reference see 5.a. above.


                                             Illustrative recurring:

                                              Interstate, intrastate $900/mo. fixed,
                                             $180/mile/mo.
- -----------------------------------------------------------------------------------------------------
</TABLE> 

/8/    Interim rates will be based on the following order of precedence: (i)
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in the
state, (iii) any Commission recommendation, or (iv) mutual agreement of the 
Parties.

/9/    See preceding note.

/10/   See note 2 above.

                                       4

<PAGE>
 
<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------
     BA SERVICE                       NON-RECURRING                  RECURRING
     ----------                       -------------                  ---------
- ----------------------------------------------------------------------------------------------
<S>  <C>                              <C>                            <C>  
6.   Local switching*                                                
                                                                     
      POTS switch Port                $6/service order plus          $1.50/mo., plus usage
                                      $6/Port                        per tariff, minus
                                                                     wholesale discount
                                                                     per section 14 below
- ----------------------------------------------------------------------------------------------
7.a. Operator services                                              
                                                               
      911 service (data entry;        No charge                     
     database maintenance)*                                    
- ----------------------------------------------------------------------------------------------
7.b.  Directory assistance            Per tariff or separate         Per tariff or separate
                                      contract; branding             contract
                                      available                     
                                                                     Illustrative tariff rates:
                                                               
                                                                     Interstate [BA FCC 1
                                                                     sec. 9.6], $.275-.288
                                                                     per call
                                                               
                                                                     Intrastate (proposed)
                                                                     [BA-VA SCC 217 sec. 
                                                                     9.6.A], $.25 per call
                                                               
                                                                     Directory transport 
                                                                     per section 1.e. above
- ----------------------------------------------------------------------------------------------
7.c.  Operator call completion        Per separate contract; branding available
- ----------------------------------------------------------------------------------------------
8.a. White pages directory listings*  $5.00 per primary              No charge
                                      listing per number            
- ----------------------------------------------------------------------------------------------
8.b.  Books & delivery (annual home   No charge for normal numbers of books
     area directories only)*          delivered to end users; bulk deliveries to 
                                      CLEC per separate arrangement
- ----------------------------------------------------------------------------------------------
</TABLE> 

                                       5
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                       NON-RECURRING         RECURRING
     ----------                       -------------         ---------
- --------------------------------------------------------------------------------
8.c.   Additional listings, changes   Per tariff [BA-VA     Per tariff [BA-VA
     to listings, non-listed, non-    SCC 203 sec. 4]       SCC 203 sec. 4]
     published, and other extra                           
     services                                             
                                      Illustrative:         Illustrative:

                                       Additional listing:  Additional listing:
                                      $9 residence; $17     $1.12/mo. residence,
                                      business              $1.42/mo. business

                                       Change to listing:   Non-list:
                                      $9 residence; $17     $1.06/mo. residence
                                      business              or business

                                       Non-list:            Non-published:
                                      $9 residence; $17     $1.71/mo. residence
                                      business              or business

                                       Non-published:
                                      $9 residence; $17
                                      business
- --------------------------------------------------------------------------------
9.   Access to telephone numbers
     (NXX codes issued per ICCF
     Code Administrative 
     Guidelines)*                     No charge

- --------------------------------------------------------------------------------
10.a SS7 Interconnection              Per interstate [BA    Per interstate [BA
                                      FCC 1 sec. 6.9.1.G]   FCC 1 sec. 6.9.1.L]
                                      and intrastate [BA-   and intrastate [BA-
                                      VA SCC 217 sec.       VA SCC 217 sec.
                                      6.8.2.C] tariff       6.8.2.G] tariff


                                                            Illustrative:

                                                             STP ports,
                                                            $900/mo.;

                                                             STP access,
                                                            $3.50/mile/mo. to
                                                            $5.72/mile/mo.
- --------------------------------------------------------------------------------

                                       6
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                   NON-RECURRING         RECURRING
     ----------                   -------------         ---------
- --------------------------------------------------------------------------------
10.b LIDB Interconnection         Per tariff [BA FCC 1  Per tariff [BA FCC 1
                                  sec. 6.9.1M]          sec. 6.9.1M]
                                                        
                                  Illustrative:         Illustrative:
                                                        
                                   Originating point     Quering validation
                                  code, $125            $.04/query
                                                        
                                                         Query transport
                                                        $.0002/query
- --------------------------------------------------------------------------------
10.c 800/888 data base            No separate charge    Per interstate [BA
     Interconnection              (including in FGD     FCC 1 sec. 6.9.2.A.1],
                                  trunk and STP links)  and intrastate [BA-VA
                                                        SCC 217 sec. 6.8.2.K]
                                                        tariffs
                                                        
                                                        
                                                        Illustrative:
                                                        
                                                        
                                                         Interstate basic query,
                                                        $.003105/query; vertical
                                                        feature package,
                                                        $.000337/query
                                                        
                                                         Intrastate basic query,
                                                        $.003089/query; vertical
                                                        feature package, 
                                                        $.000327/query
- --------------------------------------------------------------------------------
11.a Interim number portability   service order per     $3/mo. per number
     through co-carrier call      location $30          for up to 10 paths;
     forwarding                                         $.40/mo. per
                                  installation per      additional path
                                  number $35 (unless
                                  installed with
                                  unbundled loop)

                                  installation per
                                  separate path 
                                  arrangement $20
- --------------------------------------------------------------------------------

                                       7
<PAGE>
 
<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------
     BA SERVICE                         NON-RECURRING                RECURRING
     ----------                         -------------                ---------
- ----------------------------------------------------------------------------------------------
<S>  <C>                                <C>                          <C> 
11.b  Access pass-through to number                                  In accordance with 
     portability purchaser*                                          section 14.5 of 
                                                                     Agreement.
- ----------------------------------------------------------------------------------------------
12.  Local dialing parity*              No charge
- ----------------------------------------------------------------------------------------------
13.a Reciprocal call termination

      Local Traffic delivered to Bell
     Atlantic Interconnection Point
     
      First year*                                                    $.009/mou
    ------------------------------------------------------------------------------------------
      After first year*                                              In accordance with note
                                                                     13 below
- ----------------------------------------------------------------------------------------------
13.b  Access charges for termination                                 Per interstate and 
     of intrastate and interstate                                    intrastate access 
     Toll Traffic                                                    tariffs (charged in
                                                                     conjunction with Local
                                                                     Traffic, using PLU and 
                                                                     PIU, as appropriate)
- ----------------------------------------------------------------------------------------------
14.a Wholesale rates for resale of      Percentage discount from retail tariff/12/ 
                                        ------------------------------------------
     telecommunications services      
     provided to end users*/11/
- ----------------------------------------------------------------------------------------------
14.b  Individual Case Basis services    No discount
     and similar single-customer
     serving arrangements; directory
     assistance and operator call
     completion*
- ----------------------------------------------------------------------------------------------
</TABLE> 


/11/      Excludes telecommunications services designed primarily for wholesale,
such as switched and special access, and, subject to Section 12 of the
Agreement, the following additional arrangements that are not subject to resale:
limited duration promotional offerings, public coin telephone service, and
technical and market trials. Taxes shall be collected and remitted by the
reseller and BA in accordance with legal requirements and as agreed between the
Parties. Surcharges (e.g., 911, telecommunications relay service, universal
service fund) shall be collected by the reseller and either remitted to the
recipient agency or NECA, or passed through to BA for remittance to the
recipient agency or NECA, as appropriate and agreed between the Parties. End
user common line charges shall be collected by the reseller and remitted to BA.

/12/      Pending establishment of mechanized billing procedures adapted to
resale, the Parties will agree upon a composite "bottom-of-the-bill" discount
that reflects the discounts and exclusions identified herein, and such other
adjustments as the Parties agree.

                                       8
<PAGE>
 
<TABLE> 
<CAPTION>  
          ----------------------------------------------------------------------------------------------------------------
                    BA SERVICE                            NON-RECURRING               RECURRING   
                    ----------                            -------------               --------- 
          ----------------------------------------------------------------------------------------------------------------
          <S>      <C>                                    <C>                         <C>  
           14.c      IntraLATA toll, including            Discount per sections 14.d. and 14.e. below
                    discount plans*                       applied to composite weighted average toll 
                                                          rate per minute                             
          ----------------------------------------------------------------------------------------------------------------
           14.d      Other retail residential services*   6% discount
          ----------------------------------------------------------------------------------------------------------------
           14.e      Other retail business services*      9% discount
          ----------------------------------------------------------------------------------------------------------------
</TABLE> 
                                       9

<PAGE>
 
<TABLE> 
<CAPTION>  
            B.    MFS Services, Facilities, and Arrangements: 
          ----------------------------------------------------------------------------------------------------------------
                   MFS SERVICE                            NON-RECURRING               RECURRING   
                   -----------                            -------------               --------- 
          ----------------------------------------------------------------------------------------------------------------
          <S>      <C>                                    <C>                         <C>  
           1.a.    Interim Number Portability                                                          
                   through co-carrier call                                                             
                   forwarding*                                                                         

                    Number portability*                   $30/service order,          $3/mo. for ten paths
                                                          $35/number (not             per number; plus
                                                          ordered with ULL)           $.40/mo. per
                                                                                      additional path
                                                          $20 per additional
                                                          path order
          ----------------------------------------------------------------------------------------------------------------
           1.b      Access pass-though to number                                      In accordance with
                   portability purchaser*                                             sec. 14.5 of
                                                                                      Agreement
          ----------------------------------------------------------------------------------------------------------------
           2.      Local dialing parity*                  No charge
          ----------------------------------------------------------------------------------------------------------------
           3.a     Reciprocal call termination

                    Local Traffic delivered to MFS
                   Interconnection Point*

                    First year*                                                       $.009/mou
                   ---------------------------------------------------------------------------------------------------------
                    After first year*                                                 In accordance with
                                                                                      note 13 below
          ------------------------------------------------------------------------------------------------------------------
           3.b      Access charges for termination                                    Per MFS interstate
                   of intrastate and interstate Toll                                  and intrastate access
                   Traffic                                                            rates (charged in conjunction
                                                                                      with Local Traffic, using PLU
                                                                                      and PIU, as appropriate)
          ------------------------------------------------------------------------------------------------------------------
           4.      All other MFS services available       Available at MFS tariffed or otherwise         
                   to BA for purposes of                  generally available rates, not to exceed BA 
                   effectuating local exchange            rates for equivalent services available to MFS
                   competition
          ------------------------------------------------------------------------------------------------------------------
           5.       Other Services

                   Information Service billing fee        No Charge                   $.03 per call 
          ------------------------------------------------------------------------------------------------------------------
</TABLE> 

                                      10

<PAGE>
 
     LOCAL TRAFFIC TERMINATION RATES (AFTER FIRST YEAR)

A.   Charges by BA
     -------------

     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA 
          Access Tandem: $.009 per mou

     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou

     Note: All BA-IPs identified in Schedule 4.0 as of the Effective Date are
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs
     shall be subject to the rate of $.009 per mou.

B.   Charges by MFS
     --------------

1.   Single-tiered interconnection structure:

     MFS's rates for the termination of BA's Local Traffic under the single-
     tiered interconnection structure shall be recalculated once each year on
     each anniversary of the Effective Date (the "Rate Determination Date"). The
     initial Rate Determination Date shall be the first anniversary of the
     Effective Date. The methodology for recalculating the rates is as follows:

          LSWC/Access Tandem Minutes = Total minutes of use of Local Traffic
          delivered by MFS to the BA LSWC or BA Access Tandem for most recent
          billed month.

          End Office Minutes = Total minutes of use Local Traffic delivered by
          MFS directly to the terminating BA End Office for most recent billed
          month.

          Total Minutes = Total minutes of use of Local Traffic delivered by MFS
          to BA for most recent billed month.

          MFS Charge at the M-IP =

          (LSWC/Access Tandem Minutes x $.009) + (End Office Minutes x $.007)
          -------------------------------------------------------------------
                                 Total Minutes


2.   Multiple-tiered interconnection structure (if offered by MFS to any
     carrier)

     (a)  Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009

     (b)  Local Traffic delivered to terminating MFS End Office/node: $.007

                                      11
<PAGE>
 
C.   Miscellaneous Notes
     -------------------

1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended, and/
or (ii) where the Tandem Office that it subtends is not located within 25 miles
of the Tandem Office that is subtended by the terminating End Office, then such
Party shall (x) in addition to paying the LSWC/Access Tandem termination rate
described above, purchase the necessary facilities from the terminating Party to
transport such traffic to a qualifying LSWC or Access Tandem that is not subject
to either conditions (i) or (ii) above, (y) purchase such other service(s) as
the terminating Party may offer under applicable tariff to remedy such
condition(s), or (z) enter into a new compensation arrangement as the Parties
may agree. Notwithstanding the foregoing, nothing in this Agreement shall
obligate BA to provide switching services at a LSWC when it functions as such.

2.   In the event the two-tiered rate structure described above is modified 
pursuant to Applicable Law to a single rate structure, BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting 
Local Traffic it receives at its LSWC to the first point of switching in its 
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure 
set forth above is intended by the Parties to be a Local Traffic termination 
rate for Interconnection to the M-IP within each LATA that is reciprocal and 
equal to the actual rates that will be charged by BA to MFS under the 
two-tiered Local Traffic termination rate structure described above that will 
apply after the first anniversary of the Effective Date. The single MFS 
termination rate is also intended to provide financial incentives to MFS to 
deliver traffic directly to BA's terminating End Offices once MFS's traffic 
volumes reach an appropriate threshold. The Parties agree that the Reciprocal 
Compensation rate(s) set forth herein recover a reasonable approximation of each
Party's additional costs of terminating calls that originate on the network 
facilities of the other Party.

                                      12
<PAGE>
 
EXHIBIT B

                       NETWORK ELEMENT BONA FIDE REQUEST


     1.  Each Party shall promptly consider and analyze access to a new
unbundled Network Element with the submission of a Network Element Bona Fide
Request hereunder. The Network Element Bona Fide Request process set forth
herein does not apply to those services requested pursuant to Report & Order and
Notice of Proposed Rulemaking 91-141 (rel. October 19, 1992), Paragraph 259 and
Footnote 603 or subsequent orders.

     2.  A Network Element Bona Fide Request shall be submitted in writing and
shall include a technical description of each requested Network Element, the
telecommunications service(s) to be provided by the requesting Party using the
requested Network Element(s), the means of Interconnection, the number or volume
requested, the locations, and the date(s) such Network Elements are desired. The
requesting Party shall either make a binding commitment to order the Network
Elements requested in the quantity and within the time frame requested or to pay
the requested Party the costs of processing the Requests.

     3.  The requesting Party may cancel a Network Element Bona Fide Request at
any time, but shall pay the other Party's reasonable and demonstrable costs of
processing and/or implementing the Network Element Bona Fide Request up to the
date of cancellation.

     4.  Within ten (10) business days of its receipt, the receiving Party shall
acknowledge receipt of the Network Element Bona Fide Request.

     5.  Except under extraordinary circumstances, within thirty (30) days of
its receipt of a Network Element Bona Fide Request, the receiving Party shall
provide to the requesting Party a preliminary analysis of such Network Element
Bona Fide Request. The preliminary analysis shall confirm that the receiving
Party will offer access to the Network Element or will provide a detailed
explanation that access to the Network Element is not technically feasible
and/or that the request does not qualify as a Network Element that is required
to be provided under the Act.

     6.  If the receiving Party determines that the Network Element Bona Fide
Request is technically feasible and otherwise qualifies under the Act, it shall
promptly proceed with developing the requested Network Element upon receipt of
written authorization from the requesting Party. When it receives such
authorization, the receiving Party shall promptly develop the requested
services, determine their availability, calculate the applicable prices and
establish installation intervals.

     7.  Unless the Parties otherwise agree, the requested Network Element must
be priced in accordance with Section 252(d)(l) of the Act.

                                       1
<PAGE>
 
     8.  As soon as feasible, but not more than ninety (90) days after its
receipt of authorization to proceed with developing the requested Network
Element, the receiving Party shall provide to the requesting Party a Network
Element Bona Fide Request quote which will include, at a minimum, a description
of each Network Element, the availability, the applicable rates and the
installation intervals.

     9.  Within thirty (30) days of its receipt of the Network Element Bona Fide
Request quote, the requesting Party must either confirm its order for the
requested Network Element pursuant to the Network Element Bona Fide Request
quote or seek arbitration by the Commission pursuant to Section 252 of the Act.

     10.  If a Party to a Network Element Bona Fide Request believes that the
other Party is not requesting, negotiating or processing the Network Element
Bona Fide Request in good faith, or disputes a determination, or price or cost
quote, or is failing to act in accordance with section 251 of the Act, such
Party may seek mediation or arbitration by the Commission pursuant to Section
252 of the Act.

                                       2
<PAGE>
 
EXHIBIT C

                   DIRECTORY ASSISTANCE AND CALL COMPLETION
                              SERVICES AGREEMENT


     THIS AGREEMENT is made, effective this ________ day of _________,1996,
by and between BELL ATLANTIC NETWORK SERVICES, INC. (hereinafter referred to 
as "Bell Atlantic"), a Delaware corporation with offices at 13100 Columbia 
Pike, Silver Spring, MD 20904, and ________________, (hereinafter referred to 
as "Carrier"), a ______________ corporation with offices at _________________
_______________________.


1.   SCOPE AND TERM OF AGREEMENT
     ---------------------------

1.1  SCOPE This Agreement sets forth the terms and conditions which shall govern
the use of payment for Directory Assistance (DA) Service and  IntraLATA Call 
Completion Service (hereinafter collectively referred to as "Services") to be 
provided by Bell Atlantic, or its affiliated companies, to Carrier. Carrier 
shall subscribe to and pay for Services for Carrier's local exchange customers
in the _____________ LATAs.

1.2  TERM The initial term of this Agreement shall commence as of 12:01 a.m. on
the date first written above and shall expire upon the conclusion of the 
subscription period selected by Carrier in Appendix A. At the end of this 
initial term, this Agreement, including Carrier's subscription to Services, 
shall automatically renew for the same length of time as the initial 
subscription period unless either party provides written notice to the other of
its intent to terminate at least three (3) months prior to the expiration of 
the current term.

2.   DESCRIPTION OF SERVICES
     -----------------------

2.1  DIRECTORY ASSISTANCE (DA) SERVICE

     a. Directory Assistance Service shall consist of 1) directory transport by
Bell Atlantic from the point of Bell Atlantic's interconnection with Carrier's
trunks to Bell Atlantic's designated DA locations, and 2) the provision of
telephone number listings by Bell Atlantic Carrier Call Representatives (CCRs)
in response to calls from Carrier's local exchange customers located in the
LATAs designated in Section 1.1, at the rates specified in Appendix A.   

                                       1
 
        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
     b.   A maximum of two requests for telephone numbers will be accepted per 
DA call. A "DA call" as used in this Agreement shall mean a call answered by or 
forwarded to Bell Atlantic, regardless of whether a telephone number is 
requested, provided or available. The listings that will be available to 
Carrier's customers are those telephone numbers that are listed in Bell 
Atlantic's DA records for the LATAs or NPAs designated in Section 1.1.

2.2  CONNECT REQUEST(SM) SERVICE

     a)   Connect ReQuest(SM) Service is an optional DA call completion service.
It provides Directory Assistance end users the option of placing a call to a
requested DA listing without having to hang up and redial. If a caller requests
two numbers on a DA call, only the second number will be completed using
Connect ReQuest(SM).

     b)   Connect ReQuest(SM) requires that the Carrier meet switching,
facility, and other technical standards as required by Bell Atlantic to provide
this Service. Bell Atlantic will deliver all Connect ReQuest(SM) calls back to
the Carrier for completion.

2.3  INTRALATA CALL COMPLETION SERVICE

     a)   IntraLATA Call Completion Service consists of the live and automated 
call completion services specified in Appendix B, including the completion of 
collect, card and bill-to-third party calls; busy line verification; customer 
requested interrupt; and other assistance to callers. IntraLATA Call Completion 
Service includes the support of the Bell Atlantic carrier call centers and call 
completion facilities used to provide such services to Carrier.

     b)   Bell Atlantic will provide Carrier with unrated records for the call 
completion services provided by Bell Atlantic on behalf of Carrier. The rating, 
billing, and settlement of end-user charges for the calls are the responsibility
of Carrier.

2.4  BRANDING   Branding is a service option that permits the Carrier to deliver
a customized front end announcement to its callers, identifying the Carrier as
the customer service provider. Branding is available for DA as well as Call
Completion Services. Carrier shall provide the information required by Bell
Atlantic to create this announcement. Branding also requires that the Carrier
maintain dedicated trunking arrangements to the designated Bell Atlantic DA or
operator switch location.

2.5  CARRIER SUBSCRIPTION SELECTION FORM   The specific Services to which
Carrier shall subscribe and the applicable service subscription periods are
contained in Appendix A ("Carrier Subscription Selection Form").

3.   COMMENCEMENT AND IMPLEMENTATION OF SERVICE
     ------------------------------------------

                                       2

        This information is Bell Altantic Proprietary and Confidential
<PAGE>
 
3.1  TECHNICAL QUESTIONNAIRE  Each party shall make good-faith efforts to carry 
out its respective responsibilities in meeting a jointly established schedule 
for implementation. All records and other required information specified in 
Appendix C will be furnished by Carrier at least sixty (60) days prior to the 
commencement of Services (i.e., the cutover date described in Section 3.2.) 
Notices of any changes, additions, or deletions to such records and information 
shall be provided promptly in writing by Carrier to Bell Atlantic.

3.2  CUTOVER  The cutover date for a selected Services shall be the date on 
which such Service shall be available to all of Carrier's local exchange 
customers in the LATAs designated in Section 1.1.  The subscription term set 
forth in Appendix A for such Services shall commence on the cutover date.

3.3  SERVICE REVIEW MEETINGS  Bell Atlantic will meet and confer with Carrier 
during the term of this Agreement to review and discuss the Services provided 
under this Agreement. The times for meetings will be established by mutual 
agreement of the parties.


4.   EQUIPMENT AND FACILITIES
     ------------------------

4.1  BELL ATLANTIC  will establish and maintain such access equipment and
related facilities for its Carrier Call Centers as may be necessary to perform
the Services specified in Appendix A, provided that Carrier furnishes Bell
Atlantic the information specified in Appendix C and any changes in such
information in a timely and accurate manner. Any additional Services that
Carrier seeks during the term of this Agreement will be subject to mutual
agreement and the availability of facilities and equipment.

4.2  CARRIER  will provide and maintain such equipment within its premises as is
necessary to permit the Bell Atlantic to perform the agreed upon Services in
accordance with Bell Atlantic standard equipment operation and traffic operation
procedures.

4.3  CARRIER TRANSPORT AND SWITCHED ACCESS CONNECTION

     a)   Carrier shall, at its expense, arrange for and establish the trunking 
and other transport, interface, and signaling arrangements required for Bell 
Atlantic to provide Services to Carrier. Separate dedicated trunks for each NPA 
or LATA may be required. Any trunks or other transport and access that Carrier 
obtains from Bell Atlantic to deliver Carrier's call to Bell Atlantic shall be 
provided pursuant to the applicable tariffs, and not under this Agreement. Bell 
Atlantic agrees to coordinate the scheduling of Services to be provided under 
this Agreement with the scheduling of any trunking or related services, 
provisioned by Bell Atlantic under the tariffs.

                                       3

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
     b)   Carrier shall specify the number of trunks required for Services. For 
Directory Assistance Service, Carrier must provide Feature Group D (FGD) trunks 
directly to the location designated by Bell Atlantic. For IntraLATA Call 
Completion Service, Carrier must provide trunks with operator services signaling
directly to the location designated by Bell Atlantic. Bell Atlantic shall 
provide Carrier at least three (3) months advance notice in the event of any 
change in designated locations.

5.   PAYMENT FOR SERVICES
     --------------------

5.1  RATES  Carrier agrees to pay for Services at the rates contained in 
Appendix A.

5.2  SETTLEMENTS  Carrier shall render payment to Bell Atlantic net thirty (30) 
calendar days from the date of delivery of the Service or from the date of 
billing for the Service, whichever occurs later. Carrier shall pay interest on 
any amount overdue at the rate of fifteen (15) percent per annum.

5.3  TAXES  The rates specified in this Agreement and Appendices are exclusive 
of all taxes, duties or similar charges imposed by law. Carrier shall be liable 
for and shall reimburse Bell Atlantic for any sales, use, excise or other taxes 
applicable to the services performed under this Agreement.

5.4  LIQUIDATED DAMAGES  In the event that Carrier discontinues using Bell 
Atlantic's Services in whole or in part, or terminates this agreement prior to 
the expiration of the subscription term, the parties agree that Bell Atlantic   
will incur expenses and damages that will be difficult to calculate. Therefore, 
the parties agree that in the event of such discontinuance or termination, 
Carrier shall pay an amount equal to the charges billed for the month in which 
the highest usage of Services occurred, multiplied by the number of months 
remaining in the then-current term, or b) the sum of $100,000, whichever is 
greater. If Carrier causes this Agreement to terminate before the commencement 
of any Service selected in Appendix A, Carrier shall pay for all costs already 
incurred by Bell Atlantic in establishing and preparing for the commencement of 
such Service or the sum of $100,000, whichever is greater.

5.5  CARRIER'S CUSTOMERS  Carrier shall be responsible for all contacts and 
arrangements with its customers concerning the provision and maintenance, and 
the billing and collection, of charges for Services furnished to Carrier's 
customers.

6.   LIMITATION OF LIABILITY
     -----------------------

6.1  DIRECT DAMAGES  In the event that Bell Atlantic, through negligence or 
willful misconduct, fails to provide the Services selected and contracted for 
under this Agreement, Bell Atlantic shall be liable to Carrier for Carrier's 
direct damages resulting from such failure, up to an amount not to exceed the 
payment of charges under this Agreement for the Services affected.


                                       4

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
6.2   OTHER REMEDIES THE EXTENT OF BELL ATLANTIC'S LIABILITY ARISING UNDER THIS
AGREEMENT SHALL BE LIMITED AS DESCRIBED IN PARAGRAPH 6.1 ABOVE. IN NO EVENT
SHALL BELL ATLANTIC BE LIABLE FOR ANY OTHER LOSS, COST, CLAIM, INJURY,
LIABILITY, OR EXPENSE RELATED TO OR ARISING OUT OF THIS AGREEMENT OR THE
SERVICES PROVIDED HEREUNDER INCLUDING, BUT NOT LIMITED TO, ANY INCIDENTAL,
SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS
OF REVENUE OR PROFIT, WHETHER RECOVERY IS SOUGHT IN TORT, CONTRACT, OR
OTHERWISE, EVEN IF BELL ATLANTIC HAD NOTICE OF SUCH DAMAGES.


7.   DEFAULTS AND TERMINATION
     ------------------------ 

7.1  DEFAULTS OR VIOLATIONS  If Carrier defaults in the payment of any amount 
due hereunder, or if Bell Atlantic fails to provide Services as agreed 
hereunder, and such default or failure shall continue for thirty (30) days after
written notice thereof, the other company may terminate this agreement with (7) 
days written notice.

8.   CONFIDENTIAL INFORMATION
     ------------------------

8.1  CONFIDENTIALITY  The parties agree that all confidential and proprietary 
information that is marked as specified in Section 8.2 and that is disclosed by 
either party to the other party for the purposes of this Agreement, including 
rates and terms, shall be treated as confidential unless a) such information was
previously or becomes known to the receiving party free of any obligation to 
keep it confidential, b) has been or is subsequently made public by the 
disclosing party, or c) is required to be disclosed by law. The receiving party 
shall not, except in the performance of the Services under this Agreement or 
with the express prior written consent of the other party, disclose or permit 
access to any confidential information to any other parties. The parties agree 
to advise their respective employees, agents and representatives to take such 
action as may be advisable to preserve and protect the confidentiality of such 
information.

8.2  MARKETING OF CONFIDENTIAL INFORMATION  All information the disclosing party
considers proprietary or confidential, if in writing or other tangible form, 
shall be conspicuously labeled or marked as "Proprietary" or "Confidential" and,
if oral, shall be identified as proprietary at the time of disclosure and 
promptly confirmed in writing. Either party shall have the right to correct any 
inadvertent failure to designate information as proprietary by written 
notification within ten (10) days following disclosure.


9.   RELATIONSHIP OF THE PARTIES
     ---------------------------

9.1  INDEPENDENT CONTRACTORS   Bell Atlantic and Carrier shall be independent 
contractors under this Agreement and all services under this Agreement shall be 
performed by Bell Atlantic as an independent contractor and not as an agent of 
Carrier.

                                       5

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
9.2  RESPONSIBILITY FOR EMPLOYEES AND AGENTS   All persons furnished by Bell 
Atlantic shall be considered solely Bell Atlantic's employees or agents, and 
Bell Atlantic shall be responsible for compliance with all laws, rules, and 
regulations relating to such persons including, but not limited to, hours of 
labor, working conditions, workers' compensation, payment of wages, benefits, 
unemployment, social security and other payroll taxes. Each party's employees 
and agents, while on premises of the other, shall comply with all rules and 
regulations, including any applicable security procedures and safeguarding of 
confidential data.

10.  GENERAL CONDITIONS
     ------------------

10.1 ASSIGNMENT  Neither party may assign or delegate its rights and obligations
under this Agreement without the prior written consent of the other party except
that Bell Atlantic may assign this Agreement to an affiliate or subsidiary
without such consent.

10.2 CHOICE OF LAW  The validity, construction and performance of this Agreement
shall be governed by the laws of ____________________.

10.3 COMPLIANCE WITH LAWS  Each party shall comply with all applicable federal,
state, county and local laws, ordinances, regulation, rules and codes in the 
performance of this Agreement. Neither party shall be liable to the other for 
termination of this Agreement or any services to be provided hereunder 
necessitated by compliance with any law, rule, regulation or court order of a 
duly authorized governmental body.

10.4 CONTINGENCY  Neither party shall be held responsible or liable to the other
for any delay or failure in performance caused by fires, strikes, embargoes, 
requirements imposed by Government regulation, civil or military authorities, 
act of God or by the public enemy, or other causes beyond the control of Carrier
or Bell Atlantic. If such a contingency occurs, the party injured by the other's
inability to perform may: a) terminate the affected services or part thereof not
already rendered; or b) suspend the affected services or part thereof for the 
duration of the delaying cause and resume performance once the delaying causes 
cease.

10.5 LICENSES  No licenses, expressed or implied, under any patents, copyrights,
trademarks or other intellectual property rights are granted by Bell Atlantic to
Carrier under this Agreement.

10.6 NOTICES  Except as otherwise specified in this Agreement, any notice 
required or permitted under this Agreement shall be in writing and shall be 
given to the other party at the address designated below by hand delivery, 
registered return-receipt requested mail, confirmed facsimile, or nationally 
recognized courier service;

                                       6

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
               For Bell Atlantic:  Bell Atlantic Network Services, Inc.
                                   13100 Columbia Pike, D39
                                   Silver Spring, MD 20904
                                   Attn:___________, Product Manager

               For Carrier:


The above addresses may be changed by giving thirty (30) calendar days prior 
written notice as prescribed above. Notice shall be deemed to have been given or
made on the date of delivery if received by hand, facsimile or express courier, 
and three days after delivery to the U.S. Postal Service, if mailed.

10.7   PUBLICITY  Bell Atlantic and Carrier agree to submit to each other prior
to publication all advertising, sales promotions, press releases and other
publicity matters containing or mentioning a) the services performed by Bell
Atlantic under this Agreement, b) either party's name or marks, or c) language
from which either Party's names or marks may be inferred or implied. Bell
Atlantic and Carrier further agree not to publish or use any such advertising,
sales promotion, press releases, or publicity matters unless it obtains the
other party's prior written consent.

10.8   SEVERABILITY  If any provision of this Agreement or the application of
any provision shall be held by a tribunal of competent jurisdiction to be
contrary to law or unenforceable, the remaining provisions of this Agreement
shall continue in full force and effect.

10.9   SURVIVAL  All obligations hereunder, incurred by either Bell Atlantic or 
Carrier prior to the cancellation, termination or expiration of this Agreement 
shall survive such cancellation, termination or expiration.

10.10  CAPTIONS AND SECTION HEADINGS  The captions and section headings in this 
Agreement are for convenience only and do not affect the meaning or 
interpretation of this Agreement.

10.11  DUPLICATE ORIGINALS  This Agreement may be executed separately by the 
parties in one or more counterparts. Each duplicate executed shall be deemed an 
original, and all together shall constitute one and the same document.

10.12  NONDISCLOSURE OF AGREEMENT  Each party agrees not to disclose the terms 
and conditions of this Agreement to any third party, except that it shall not be
deemed a breach of this provision for the parties to disclose the terms and 
conditions of this

                                       7

<PAGE>
 
Agreement to their respective subsidiaries and affiliated companies or to any 
duly constituted governmental body which requires disclosure.

10.13 ENTIRE AGREEMENT  The terms and conditions of this Agreement, including 
Appendices A, B, and C attached to this Agreement, constitute the entire 
Agreement between Bell Atlantic and Carrier relating to the subject matter of 
this Agreement, and supersede any and all prior or contemporaneous 
understandings, promises or representations, whether written or oral, between 
the parties relating to the subject matter of this Agreement. Any waiver, 
modification or amendment of any provision of this Agreement, or of any right or
remedy hereunder, shall not be effective unless made in writing and signed by 
both parties.

IN WITNESS WHEREOF, the parities agree that the effective date of this 
Agreement is the date first written above, and each party warrants that it has 
caused this Agreement to be signed and delivered by its duly authorized 
representative.


BELL ATLANTIC
NETWORK SERVICES, INC.


NAME:__________________________         NAME:____________________________

TITLE:_________________________         TITLE:___________________________

SIGNATURE:_____________________         SIGNATURE:_______________________

DATE:__________________________         DATE:____________________________

                                       8

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
                                                                      APPENDIX A

                     CARRIER SUBSCRIPTION SELECTION FORM
                     -----------------------------------

- --------------------------------------------------------------------------------
 CONTRACT DA SERVICE                      SUBSCRIPTION         RATE PER
 SELECTED                                 PERIOD               CALL
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - STANDARD                YEAR(S)                
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - STANDARD WITH 
 FRONT END BRANDING*                            YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE           YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE
 WITH FRONT END BRANDING*                       YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE CALL COMPLETION           YEAR(S)
- --------------------------------------------------------------------------------
 INTRALATA CALL COMPLETION                      YEAR(S)        SEE RATES BELOW 
- --------------------------------------------------------------------------------
 BRANDED INTRALATA CALL COMPLETION*             YEAR(S)        SEE RATES BELOW
- --------------------------------------------------------------------------------
 * PLUS NONRECURRING BRANDING FEE OF $ _________.

 For informational purposes, the following are the charges for Directory 
 Transport to be provided under the applicable tariffs. (Call miles are measured
 from the BA Wire Center serving Carrier's premises to the DA location):

     Call Miles                                    Rate Per Call
     ----------                                    -------------
     0 to 1 mile ............................... $ 0.0014
     > 1 to 4 miles ............................   0.0015
     > 4 to 8 miles ............................   0.0016
     > 8 to 16 miles ...........................   0.0018
     > 16 to 25 miles ..........................   0.0018
     > 25 to 50 miles ..........................   0.0019
     > 50 to 200 miles .........................   0.0020

- --------------------------------------------------------------------------------
                             CALL COMPLETION RATES
- --------------------------------------------------------------------------------
 TOTAL ANNUAL CALL VOLUME    AUTO       AUTO COLLECT/      LIVE CCR HANDLED
 (ALL CALLS)                PER CALL    THIRD (PER CALL)   PER CCR WORK SECOND
- --------------------------------------------------------------------------------
 0 - 20,000          
- --------------------------------------------------------------------------------
 20,001 - 100,000
- --------------------------------------------------------------------------------
 100,001 +
- --------------------------------------------------------------------------------
 Notes: 1) Trunking and switched access costs are not included in the above DA 
 ------    
           and Call Completion rates.

        2) Rates for automated IntraLATA Call Completion calls are based on call
           attempts.

_________________________________
SIGNATURE (BELL ATLANTIC)

                                       9

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
                           BELL ATLANTIC RATE SHEET

             VIRGINIA LOCAL EXCHANGE CARRIER DIRECTORY ASSISTANCE


   DIRECTORY ASSISTANCE CALL CHARGE (PER CALL, BASED ON LENGTH OF CONTRACT)

 Type of Service                     Month-to Month        1-year      3-year
 ---------------                    ----------------      --------    --------

- --------------------------------------------------------------------------------
 Standard                           $.275             $.25          $.23
- --------------------------------------------------------------------------------
 Standard w/Customized Branding*     .278              .253          .233
- --------------------------------------------------------------------------------
 Live Carrier Call Representative 
 (CCR)                               .285              .26           .24   
- --------------------------------------------------------------------------------
 Live CCR w/Customized Branding*     .288              .263          .243
- --------------------------------------------------------------------------------

 * Customized branding fee (non-recurring charge): $6,000


       CONNECT REQUEST(TM) DIRECTORY ASSISTANCE CALL COMPLETION (OPTIONAL)

- --------------------------------------------------------------------------------
 Charge per Request (in addition 
 to above charges)                  $.27              $.25          $.22
- --------------------------------------------------------------------------------



                          DIRECTORY TRANSPORT CHARGE

 (For each call to Directory Assistance service; call miles measured from the 
 wire center serving the customer's premises to the DA location).

     Call Miles                                 Rate Per Call
     ----------                                 -------------

     0 to 8 ................................. $ 0.0037
     * 8 to 13 ..............................   0.0062
     * 13 to 18 .............................   0.0076
     * 18 to 23 .............................   0.0089
     * 23 to 28 .............................   0.0137
     * 28 miles .............................   0.0223


 Trunk installation charges are not included.
 
*  Greater than
 
<PAGE>
 
                                                         [LOGO OF BELL ATLANTIC]

<TABLE> 
<CAPTION> 
                                                      PROPOSED PRICING TERMS

                                                INTRALATA CALL COMPLETION SERVICES

                                                COMPETITIVE LOCAL EXCHANGE CARRIERS

                                                  (Prices effective June 1, 1996)

- ---------------------------------------------------------------------------------------------------------------------------------- 
                            TWO YEAR TERM                       THREE YEAR TERM                        FIVE YEAR TERM
- ---------------------------------------------------------------------------------------------------------------------------------- 
TOTAL ANNUAL        Auto        Auto        Operator      Auto        Auto        Operator      Auto        Auto        Operator  
CALL VOLUME         Card        Collect/    Handled       Card        Collect/    Handled       Card        Collect/    Handled
(all calls)         (per call)  Third       (per OWS)     (per call)  Third       (per OWS)     (per call)  Third       (per OWS)  
                                (per call)                            (per call)                            (per call)  
- ---------------------------------------------------------------------------------------------------------------------------------- 
<S>                 <C>         <C>         <C>           <C>         <C>         <C>           <C>         <C>         <C> 
0 - 20,000           $0.15       $0.20       $0.0145       $0.14       $0.19       $0.0141       $0.13       $0.18       $0.0136
- ---------------------------------------------------------------------------------------------------------------------------------- 
20,001 - 100,000     $0.14       $0.19       $0.0141       $0.13       $0.18       $0.0136       $0.12       $0.17       $0.0131
- ---------------------------------------------------------------------------------------------------------------------------------- 
100,000 +            $0.13       $0.18       $0.0136       $0.12       $0.17       $0.0131       $0.11       $0.16       $0.0126
- ---------------------------------------------------------------------------------------------------------------------------------- 
</TABLE> 


Notes:    Trunking costs are not included in the above rates.
          The rates quoted above for automated calls are based on call attempts.
          All prices include company specific branding.



                            PROPRIETARY INFORMATION
                NOT FOR USE OR DISCLOSURE OUTSIDE BELL ATLANTIC
                        EXCEPT UNDER WRITTEN AGREEMENT.

<PAGE>                                                      

                                                                      APPENDIX B
 
                      INTRALATA CALL COMPLETION SERVICES
                      ----------------------------------
A.   Calling Card
     ------------
     Bell Atlantic Carrier Call Representative keys the calling card number and 
     call details into the system, secures validation, and releases the call 
     into the network.

B.   Collect
     -------
     Bell Atlantic Carrier Call Representative obtains the calling party's name,
     keys the call details if necessary, announces the call to the called party,
     waits for acceptance, and releases the call into the network.

C.   Billed To A Third Party
     -----------------------   
     Bell Atlantic Carrier Call Representative requests the calling party's 
     name, keys the call details if necessary, calls the third party to verify
     acceptance of billing, and releases the call once acceptance is given.

D.   Assistance - Other
     ------------------
     Bell Atlantic Carrier Call Representative will dial a called number for the
     customer for any of the following reasons:

     1. Customer encounters trouble such as wrong number, poor transmission or
     cutoff, and requests a credit or reconnection.

     2. Customer desires time and charges at the end of conversation.

     3. Customer requires dialing assistance due to a disability..

     4. Customer is unwilling to dial call.

E.   Person-to-Person
     ----------------
     Bell Atlantic Carrier Call Representative requests the person or department
     the calling party has specified, ensures appropriate party has been reached
     (person or department), and releases call.

F.   Busy-Line Verification
     ----------------------
     Bell Atlantic Carrier Call Representative determines if the number
     specified by the customer is in use, idle, or out of order.

G.   Customer-Requested Interrupt
     ----------------------------

                                      10

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
     At the customer's request, Bell Atlantic Carrier Call Representative will 
     interrupt conversation in progress on a line that has been verified in use.
                                                             APPENDIX B (CONT'D)

H.   Assistance (0-)
     ---------------
     Bell Atlantic Carrier Call Representative will provide customer dialing
     instructions, assistance with emergency calls, area code information, and
     business office or repair service.

I.   Validation Services
     -------------------
     Bell Atlantic will launch a query for the validation of all calling card
     calls, collect calls, billed-to-third number calls and public telephone
     checks to a Line Information Data Base (LIDB). The query costs for query of
     the Bell Atlantic LIDB are included in Bell Atlantic Carrier Call
     Representative (CCR) Work Second or Automated call rate specified in
     Appendix A. Bell Atlantic will also launch queries as stated for
     validations to other companies' LIDBs.

                                      11

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
                                                                      APPENDIX C


                            EXCHANGE OF INFORMATION
                            -----------------------


Technical information will be furnished via the use of a Technical Questionnaire
to be provided by Bell Atlantic.  Such information will include, but not be 
limited to, the following:


1.   Central Office Exchange Names
2.   Usage Forecasts
3.   Local Central Office Characteristics
4.   Trunking Arrangements and Trunk Group Types
5.   Emergency Reporting System and Procedures
6.   Business Office Information
7.   Repair Service Information
8.   Name and Address Request Information
9.   Tariffs and Rate Information
10.  Customer Dialing Capabilities
11.  Access to EMI Records

                                      12

        This information is Bell Atlantic Proprietary and Confidential


<PAGE>
 
                                AMENDMENT NO. 2

                                    TO THE

                           INTERCONNECTION AGREEMENT

                                    BETWEEN

                          BELL ATLANTIC-VIRGINIA, INC.

                                      AND

                        MFS INTELENET OF VIRGINIA, INC.



     This Amendment No. 2 is made this 29th day of July, 1997, by and between
Bell Atlantic-Virginia, Inc. ("BA"), a Virginia corporation with offices at 600
East Main Street, Richmond, Virginia 23219, and MFS Intelenet of Virginia, Inc.
("MFS"), a Delaware corporation with offices at 33 Whitehall Street, 15th Floor,
New York, New York 10004. (BA and MFS may be referred to individually as a
"Party" and collectively as the "Parties").


                                  WITNESSETH:
                                  ----------

     Whereas, BA and MFS are Parties to an Interconnection Agreement under
Sections 251 and 252 of the Telecommunications Act of 1996 dated effective as of
July 16, 1996 (the "Agreement"); and

     Whereas, the Parties now desire to amend the Agreement to reflect the
agreement between the Parties to permit MFS, pursuant to Section 251(c)(4) of
the Communications Act of 1934, to purchase retail telecommunications services
from BA for resale by MFS in the State of Virginia;

     NOW, THEREFORE, in consideration of the promises and mutual agreements
herein contained, the Parties agree to amend the Agreement as follows:

     1.   Remove the existing cover page through page 64 of the Agreement and
     insert the attached revised cover page through page 63 of the Agreement,
     which includes deletion of the existing Section 12.0. Resale, in its
     entirety, and insertion of a revised Section 12.0, Resale, in its entirety.

     2.   Insert a new Schedule 12.3. Support Services for Resale as attached
     hereto.

                                       1


<PAGE>
 
     3.   Delete the existing Exhibit A and insert the revised Exhibit A as 
     attached hereto.

     4.   Except for the foregoing, the substantive terms and provisions 
     contained in the Agreement shall remain in full force and effect.

     This Amendment may be executed in counterparts, each of which shall be 
deemed an original and all of which together shall constitute one and the same 
instrument.





                          [Intentionally Left Blank]

                                       2
<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be
duly executed as of the date first set forth above.





MFS INTELENET OF                            BELL ATLANTIC-
 VIRGINIA, INC.                              VIRGINIA, INC.



By: /s/ Kevin J Dundon                      By: ______________________
   ---------------------------

Printed: Kevin J Dundon                     Printed:__________________
         ----------------------

Title: Vice President -                     Title:____________________
      -------------------------
      Local Network Development

<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be
duly executed as of the date first set forth above.




MFS INTELENET OF                            BELL ATLANTIC-    
 VIRGINIA, INC.                              VIRGINIA, INC.


By:_______________________                  By: H. R. Stallard
                                               ------------------------------- 

Printed:__________________                  Printed: H. R. Stallard
                                                    --------------------------

Title:____________________                  Title: President and CEO 
                                                  ---------------------------- 

                                       3
<PAGE>
 

         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE 
                        TELECOMMUNICATIONS ACT OF 1996


                           Dated as of July 16, 1996


                                by and between


                         BELL ATLANTIC-VIRGINIA, INC.


                                      and


                        MFS INTELENET OF VIRGINIA, INC.
<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------

<TABLE> 
<CAPTION> 
                                                                            Page
                                                                            ----
<S>                                                                         <C> 
1.0  DEFINITIONS                                                               2

2.0  INTERPRETATION AND CONSTRUCTION                                          10

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE             11

4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)                            11
4.1  Scope                                                                    12
4.2  Physical Architecture                                                    13
4.3  Initial Architecture                                                     13
4.4  Interconnection in Additional LATAs                                      14
4.5  Interconnection Points for Different Types of Traffic                    15

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE 
     TRAFFIC PURSUANT TO SECTION 251(c)(2)                                    15
5.1  Scope of Traffic                                                         15
5.2  Trunk Group Connections and Ordering                                     15
5.3  Additional Switching System Hierarchy and Trunking Requirements          15
5.4  Signaling                                                                16
5.5  Grades of Service                                                        16
5.6  Measurement and Billing                                                  16
5.7  Reciprocal Compensation Arrangements -- Section 251(b)(5)                17

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 
     251(c)(2)                                                                18
6.1  Scope of Traffic                                                         18
6.2  Trunk Group Architecture and Traffic Routing                             18
6.3  Meet-Point Billing Arrangements                                          19
6.4  800/888 Traffic                                                          21

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC                      22
7.1  Information Services Traffic                                             22
7.2  LSV/VCI Traffic                                                          23
7.3  Transit Service                                                          24
7.4  911 E911 Arrangements                                                    25
7.5  Ancillary Traffic Generally                                              26

8.0  NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS                        26
</TABLE> 

                                       i
<PAGE>
 
 
<TABLE> 
<S>                                                                           <C>
9.0  NETWORK MAINTENANCE AND MANAGEMENT: OUTAGES                              26

9.3  Interference or Impairment                                               28
9.4  Repeated or Willful Noncompliance                                        28
9.5  Outage Repair Standard                                                   28
9.6  Notice of Changes -- Section 251(c)(5)                                   28

10.0 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND INSTALLATION,
     MAINTENANCE, TESTING AND REPAIR                                          28
10.1 Joint Network Reconfiguration and Grooming Plan                          28
10.2 Installation, Maintenance, Testing and Repair                            29
10.3 Forecasting Requirements for Trunk Provisioning                          29

11.0 UNBUNDLED ACCESS -- SECTION 251(c)(3)                                    30
11.1 Unbundled Local Loop (ULL) Transmission Types                            30
11.2 Port Types                                                               31
11.3 Trunk Side Local Transport                                               32
11.4 Limitations on Unbundled Access                                          32
11.5 Availability of Other Network Elements on an Unbundled Basis             33
11.6 Provisioning of Unbundled Local Loops                                    33
11.7 Maintenance of Unbundled Local Loops                                     35
11.8 Rates and Charges                                                        35

12.0 RESALE -- SECTIONS 251(c)(4) and 251(b)(1)                               35
12.1 Availability of Retail Rates for Resale                                  35
12.2 Availability of Wholesale Rates for Resale                               35
12.3 Availability of Support Services and Branding for Resale                 35
12.4 Additional Terms Governing Resale and Use of BA Services                 35

13.0 COLLOCATION -- SECTION 251(c)(6)                                         36

14.0 NUMBER PORTABILITY -- SECTION 251(b)(2)                                  37
14.1 Scope                                                                    37
14.2 Procedures for Providing INP Through Remote Call Forwarding              38
14.3 Procedures for Providing INP Through Direct Inward Dial Trunks 
     (Flex-DID)                                                               39
14.4 Procedures for Providing LTNP Through Full NXX Code Migration            39
14.5 Receipt of Terminating Compensation on Traffic to INP'ed Numbers         39
14.6 Recovery of INP Costs Pursuant to FCC Order and Rulemaking               40

15.0 DIALING PARITY -- SECTION 251(b)(3)                                      41

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                             41
</TABLE> 

                                      ii

<PAGE>
 
 
<TABLE> 
<S>                                                                   <C> 
17.0      DATABASES AND SIGNALING                                     41

18.0      COORDINATED SERVICE ARRANGEMENTS                            42
18.1      Intercept and Referral Announcements                        42
18.2      Coordinated Repair Calls                                    43
18.3      Customer Authorization                                      43

19.0      DIRECTORY SERVICES ARRANGEMENTS                             43
19.1      Directory Listings and Directory Distributions              44
19.2      Yellow Page Maintenance                                     45
19.3      Service Information Pages                                   45
19.4      Directory Assistance (DA): Call Completion                  46

20.0      COORDINATION WITH TARIFF TERMS                              45

21.0      INSURANCE                                                   46

22.0      TERM AND TERMINATION                                        47

23.0      DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                48

24.0      CANCELLATION CHARGES                                        48

25.0      INDEMNIFICATION                                             48

26.0      LIMITATION OF LIABILITY                                     49

27.0      PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES              50
27.1      Certain Definitions                                         50
27.2      Performance Standards                                       51
27.3      Limitations                                                 51
27.4      Service Quality Standards                                   52
27.5      Records                                                     52

28.0      COMPLIANCE WITH LAWS; REGULATORY APPROVAL                   52

29.0      MISCELLANEOUS                                               53
29.1      Authorization                                               53
29.2      Independent Contractor                                      53
29.3      Force Majeure                                               53
29.4      Confidentiality                                             54
29.5      Choice of Law                                               55
29.6      Taxes                                                       55
29.7      Assignment                                                  57
29.8      Billing and Payment; Disputed Amounts                       57
</TABLE> 

                                      iii

<PAGE>
 

<TABLE> 
<S>                                                                   <C> 
29.9      Dispute Resolution                                          58
29.10     Notices                                                     59
29.11     Section 252(i) Obligations                                  59
29.12     Joint Work Product                                          60
29.13     No Third Party Beneficiaries; Disclaimer of Agency          61
29.14     No License                                                  61
29.15     Technology Upgrades                                         61
29.16     Survival                                                    62
29.17     Entire Agreement                                            62
29.18     Counterparts                                                62
29.19     Modifications, Amendment, Supplement or Waiver              62
29.20     Successors and Assigns                                      62
29.21     Publicity                                                   62
</TABLE> 


                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------

Schedules
- ---------

Schedule 1.0   Certain Terms As Defined in the Act, As of July 16, 1996
Schedule 3.0   Implementation Schedule
Schedule 4.0   Interconnection Points in LATA
Schedule 4.2   Physical Architecture Diagram
Schedule 4.3   Initial Architecture Diagram
Schedule 4.5   Interconnection Points for Different Types of Traffic
Schedule 6.3   Rate Elements Under Meet Point Billing
Schedule 12.3  Support Services for Resale
Schedule 27.0  Performance Interval Dates for Specified Activities
Schedule 27.1  MFS Service Quality Standards


Exhibits
- --------

Exhibit A      Detailed Schedule of Itemized Charges
Exhibit B      Network Element Bona Fide Request
Exhibit C      Directory Assistance and Call Completion Services Agreement

                                      iv
<PAGE>
 
         INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996


     This Interconnection Agreement under Sections 251 and 252 of the
 Telecommunications Act of 1996, is effective as of the 16th day of July, 1996 
(the"Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a 
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia 
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with 
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched 
Exchange Access Services, and other Telecommunications Services (all as defined 
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will interconnect their networks and provide other services as 
required by the Act (as defined below) and additional services as set forth 
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996 
have specific requirements for interconnection, unbundling, and service resale, 
commonly referred to as the "Checklist", and the Parties intend that this
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein 
and other good and valuable consideration, the receipt and sufficiency of which 
are hereby acknowledged, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA 
and MFS (individually, a "Party" and collectively, the  "Parties") will offer 
and provide to each other network Interconnection, access to Network Elements, 
ancillary services, and wholesale Telecommunications Services available for 
resale within each LATA in which they both operate within Virginia.  As such, 
this Agreement is an integrated package that reflects a balancing of interests 
critical to the Parties. It will be submitted to the Virginia State Corporation
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of
the Agreement. So long as the Agreement remains in effect, neither Party shall
advocate before any legislative, regulatory, or other public forum that any term
of this Agreement be modified or eliminated, unless otherwise mutually agreed by
the Parties.

                                       1

<PAGE>
 
1.0  DEFINITIONS.

     As used in this Agreement, the following terms shall have the meanings 
specified below in this Section 1.0. For convenience of reference only, the 
definitions of certain terms that are As Defined in the Act (as defined below) 
are set forth on Schedule 1.0.

     1.1   "Act" means the Communications Act of 1934 (47 U.S.C. 151 et. seq.),
                                                                      -- ---
as amended by the Telecommuications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission.

     1.2   "ADSL" or "Asymmetrical Digital Subscriber Line" means a transmission
technology which transmits an asymmetrical digital signal of up to 6 mbps to the
Customer and up to 640 kbps from the Customer.

     1.3   [Reserved]

     1.4   "Agreement" means this Interconnection Agreement under Sections 251
and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5   "Ancillary Traffic," means all traffic that is destined for ancillary
services, or that may have special billing requirements, including but not
limited to the following: LSV/VCI, Directory Assistance, 911/E911, Operator
Services (call completion), 800/888 database query, LIDB, and information
services requiring special billing.

     1.6   "As Defined in the Act" means as specifically defined by the Act
and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.7   "As Described in the Act" means as described in or required by 
the Act and as from time to time interpreted in the duly authorized rules and 
regulations of the FCC or the Commission.

     1.8   "Automatic Number Identification" or "ANI" means a Feature Group 
D signaling parameter which refers to the number transmitted through a network
identifying the billing number of the calling party.

     1.9   "Calling Party Number" or "CPN" is a Common Channel Signaling 
("CCS") parameter which refers to the number transmitted through a network 
identifying the calling party.

     1.10  "Central Office Switch" means a switch used to provide
Telecommunications Services, including, but not limited to:

           (a) "End Office Switch" or "End Office" which is used to
terminate Customer station Loops for the purpose of interconnection to each
other and to trunks; and

                                       2

<PAGE>
 
           (b) "Tandem Switch" or "Tandem Office" which is a switching entity
that is used to connect and switch trunk circuits between and among End Office
Switches and between and among End Office Switches and carriers' aggregation
points, points of termination, or points of presence. An "Access Tandem Office"
or "Access Tandem" is a Tandem Office with billing and recording capabilities
that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End
Office/Tandem Office Switch.

     1.11  [Reserved]

     1.12  "CLASS Features" means certain CCS-based features available to
Customers including, but not limited to: Automatic Call Back: Call Trace: Caller
Identification, and future offerings.

     1.13  "Collocation" means an arrangement whereby one Party's (the
"Collocating Party") facilities are terminated in equipment necessary for
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a
second Party (the "Housing Party"). For purposes of Collocation, the "premises"
of a Housing Party is limited to a Housing Party Wire Center, other mutually
agreed-upon locations of the Housing Party, or any other location for which
Collocation has been ordered by the FCC or Commission. Collocation may be
"physical" or "virtual". In "Physical Collocation," the Collocating Party
installs and maintains its own equipment in the Housing Party's premises. In
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA
currently provides Collocation under terms, rates, and conditions as described
in tariffs on file or soon to be filed with the FCC and the Commission. Upon
request by either Party, BA and MFS will address the provision of additional
types of Collocation arrangements, including additional physical locations and
alternative utilizations of space and facilities.

     1.14  "Commission" means the Virginia State Corporation Commission.

     1.15  "Common Channel Signaling" or "CCS" means a method of transmitting
call set-up and network control data over a digital signaling network separate
from the public switched telephone network facilities that carry the actual
voice or data traffic of the call. "SS7" means the common channel out of band
signaling protocol developed by the Consultative Committee for International
Telephone and Telegraph ("CCITT") and the American National Standards Institute
("ANSI"). BA and MFS currently utilize this out-of-band signaling protocol.
"CCSAC" or "CCSAS" means the common channel signaling access connection or
service, respectively, which connects one Party's signaling point of
interconnection "SPOI") to the other Party's STP for the exchange of SS7 
messages.

                                       3
<PAGE>
 
     1.16  "Competing Local Exchange Carrier" or "CLEC" means any Local
Exchange Carrier other than BA, operating as such in BA's certificated
territory in Virginia. MFS is or will shortly become a CLEC.

     1.17  "Cross Connection" means a jumper cable or similar connection
provided pursuant to Collocation at the digital signal cross connect, Main
Distribution Frame or other suitable frame or panel between (i) the Collocating
Party's equipment and (ii) the equipment or facilities of the Housing Party.

     1.18  "Customer" means a third-party residence or business subscriber to
Telecommunications Services provided by either of the Parties.

     1.19  "Dialing Parity" is As Defined in the Act.

     1.20  "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.21  "Digital Signal Level 0" or "DS0" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.

     1.22  "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level
signal in the time-division multiplex hierarchy. In the time-division
multiplexing hierarchy of the telephone network, DS1 is the initial level of
multiplexing.

     1.23  "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level
in the time-division multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS3 is defined as the third level of
multiplexing.

     1.24  "Exchange Access" is As Defined in the Act.

     1.25. "Exchange Message Record" or "EMR" means the standard used for
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is
contained in BR-0l0-200-O10 CRIS Exchange Message Record, a Bell Communications
Research, Inc. ("Bellcore") document that defines industry standards for
Exchange Message Records.

     1.26  [Reserved]

     1.27  "FCC" means the Federal Communications Commission.

     1.28  "HDSL" or "High-Bit Rate Digital Subscriber Line" means a
transmission technology which transmits up to 784 kbps simultaneously in both
directions on a two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line
code.

                                       4
<PAGE>
 
      1.29  "Independent Telephone Company" or "ITC" means any entity other
than BA which, with respect to its operations within Virginia, is an "Incumbent
Local Exchange Carrier" As Described in the Act.

     1.30  "Information Service Traffic" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which is
addressed to an information service provided over a Party's information services
platform.

     1.31  "Integrated Digital Loop Carrier" means a subscriber loop carrier
system which integrates within the switch at a DS1 level that is twenty-four 
(24) loop transmission paths combined into a 1.544 Mbps digital signal.

     1.32.  "Integrated Services Digital Network" or "ISDN" means a switched
network service providing end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN") provides
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B-D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for
digital transmission of twenty three (23) 64 kbps bearer channels and one 16
kbps data and signaling channel (23 B+D).

     1.33  "Interconnection" is as Described in the Act, and means the
connection of separate pieces of equipment or transmission facilities within,
between, or among networks. The architecture of Interconnection may include,
but is not limited to, Collocation Arrangements, entrance facilities, and Mid-
Span Meet arrangements.

     1.34  "Interexchange Carrier" or "IXC" means a carrier that provides,
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35  "Interim Number Portability" or "INP" means the use of existing and
available call routing, forwarding, and addressing capabilities (e.g. remote 
                                                                 - -
call forwarding) to enable a Customer to receive Telephone Exchange Service
provided by any Local Exchange Carrier operating within the exchange area with
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of
whether the Customer's chosen Local Exchange Carrier is the carrier that
originally assigned the number to the Customer.

     1.36  "InterLATA" is As Defined in the Act.

     1.37  "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.38  "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.

                                       5
<PAGE>
 
     1.39.     "Line Status Verification" or "LSV" means an operator request for
a status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40.     "Local Access and Transport Area" or "LATA" is As Defined in the 
Act.

     1.41.     "Local Exchange Carrier" or "LEC" is As Defined in the Act. The 
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42.     "Local Serving Wire Center" means a Wire Center that (i) serves 
the area in which the other Party's or a third party's Wire Center, aggregation 
point, point of termination, or point of presence is located, or any Wire 
Center in the LATA in which the other Party's Wire Center, aggregation point, 
point of termination or point of presence is located in which the other Party 
has established a Collocation Arrangement or is purchasing an entrance facility,
and (ii) has the necessary multiplexing capabilities for providing transport 
services.

     1.43.     "Local Telephone Number Portability" or LTNP" means "number 
portability" As Defined in the Act.

     1.44      "Local Traffic," means traffic that is originated by a Customer
of one Party on that Party's network and terminates to a Customer of the other
Party on that other Party's network, within a given local calling area, or
expanded area service ("EAS") area, as defined in BA's effective Customer
tariffs. Local Traffic does not include traffic originated or terminated by a
commercial mobile radio service carrier.

     1.45.     "Main Distribution Frame" or "MDF" means the primary point at 
which outside plant facilities terminate within a Wire Center, for 
interconnection to other telecommunications facilities within the Wire Center.

     1.46.     "MECAB" means the Multiple Exchange Carrier Access Billing 
(MECAB) document prepared by the Billing Committee of the Ordering and Billing 
Forum ("OBF"), which functions under the auspices of the Carrier Liaison 
Committee ("CLC") of the Alliance for Telecommunications Industry Solutions 
("ATIS"). The MECAB document, published by Bellcore as Special Report 
SR-BDS-000983, contains the recommended guidelines for the billing of an 
Exchange Access service provided by two or more LECs, or by one LEC in two or 
more states, within a single LATA.

     1.47.     "MECOD" means the Multiple Exchange Carriers Ordering and Design 
(MECOD) Guidelines for Access Services - Industry Support Interface, a document 
developed by the Ordering/Provisioning Committee under the auspices of OBF. The
MECOD document, published by Bellcore as Special Report SR-STS-002643, 
establishes methods for processing orders for Exchange Access service which is 
to be provided by two or more LECs.

     1.48.     "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched 
Exchange Access Service to one

                                       6
<PAGE>
 
of the LEC's End Office Switches, with each LEC receiving an appropriate share
of the transport element revenues as defined by their effective Exchange Access
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an
effective Meet-Point Billing arrangement.

     1.49  "Mid-Span Meet" means an Interconnection architecture whereby two 
carriers' fiber transmission facilities meet at a mutually agreed-upon 
Interconnection point.

     1.50  "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff"
means the MPB method whereby each LEC prepares and renders its own meet point 
bill in accordance with its own Tariff(s) for the portion of the 
jointly-provided Switched Exchange Access Service which the LEC provides.

     1.51  "Network Element" is As Defined in the Act.          

     1.52  "Network Element Bona Fide Request" means the process described on 
Exhibit B that prescribes the terms and conditions relating to a Party's request
that the other Party provide a Network Element not otherwise provided by the 
terms of this Agreement.

     1.53  "North American Numbering Plan" or "NANP" means the numbering plan 
used in the United States that also serves Canada, Bermuda, Puerto Rico and 
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 
3-digit NXX code and 4-digit line number.

     1.54  "Numbering Plan Area" or "NPA" is also sometimes referred to as an
area code. There are two general categories of NPAs, "Goegraphic NPAs" and "Non-
Geographic NPAs" A Geographic NPA is associated with a defined geographic area,
and all telephone numbers bearing such NPA are associated with services provided
within that geographic area. A Non-Geographic NPA, also known as a "Service
Access Code" or "SAC Code" is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55  "NXX," "NXX Code," or "End Office Code" means the three digit switch 
entity indicator (i.e. the first three digits of a seven digit telephone 
                  - -
number).

     1.56  "Permanent Number Portability" or "PNP" means the use of a database 
or other technical solution that comports with regulations issued by the FCC to 
provide LTNP for all customers and service providers.

     1.57  "Port Element" or "Port" means a line card (or equivalent) and 
associated peripheral equipment on an End Office Switch which serves as the 
Interconnection between individual loops or individual Customer trunks and the 
switching components of an End Office Switch and the associated switching 
functionality in that End Office Switch. Each ?? is typically associated with 
one (or more) telephone number(s) which serves as the Customer's network 
address.

                                       7

<PAGE>
 
     1.58 "Rate Center Area" or "Exchange Area" means the specific geographic 
point and corresponding geographic area which has been identified by a given LEC
as being associated with a particular NPA-NXX code assigned to the LEC for its 
provision of Telephone Exchange Services. The Rate Center Area is the exclusive 
geographic area which the LEC has identified as the area within which it will 
provide Telephone Exchange Services bearing the particular NPA-NXX designation 
associated with the specific Rate Center Area. A "Rate Center Point" is a 
specific geographic point, defined by a V&H coordinate, located within the Rate 
Center Area and used to measure distance for the purpose of billing Customers 
for distance-sensitive Telephone Exchange Services and Toll Traffic.

     1.59 "Rate Demarcation Point" means the point of minimum penetration at the
Customer's premises or other point, as defined in a Party's Tariffs, where 
network access recurring charges and LEC responsibility ends and beyond which 
Customer responsibility begins.

     1.60 "Rating Point" or "Routing Point" means a specific geographic point 
identified by a specific V&H coordinate. The Rating Point is used to route 
inbound traffic to specified NPA-NXXs and to calculate mileage measurements for 
distance-sensitive transport charges of switched access services. Pursuant to 
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office 
location, or a "LEC  Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common 
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point 
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point corresponding to each unique and separate Rate Center.

     1.61 "Reciprocal Compensation" is As Described in the Act, and refers to 
the payment arrangements that recover costs incurred for the transport and 
termination of Local Traffic originating on one Party's network and terminating 
on the other Party's network.

     1.62 "Service Control Point" or "SCP" means the node in the common channel 
signaling network to which informational requests for service handling, such as 
routing, are directed and processed. The SCP is a real time database system 
that, based on a query from a service switching point and via a Signaling 
Transfer Point, performs subscriber or application-specific service logic, and 
then sends instructions back to the SSP on how to continue call processing.

     1.63 "Signaling Transfer Point" or "STP" means a specialized switch that 
provides SS7 network access and performs SS7 message routing and screening.

     1.64 "Switched Access Detail Usage Data" means a category 1101XX record as 
defined in the EMR Bellcore Practice BR-010-200-010.

     1.65 "Switched Access Summary Usage Data" means a category 1150XX record as
defined in the EMR Bellcore Practice BR-010-200-010.

                                       8

<PAGE>
 
     1.66   "Switched Exchange Access Service" means the offering of 
transmission and switching services for the purpose of the origination or 
termination of Toll Traffic. Switched Exchange Access Services include but may 
not be limited to: Feature Group A, Feature Group B, Feature Group D, 700 
access, 800 access, 888 access, and 900 access.

     1.67   "Synchronous Optical Network" or "SONET" means an optical interface 
standard that allows inter-networking of transmission products from multiple 
vendors. The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are direct 
multiples of the base rate, up to 13.22 Gpbs.

     1.68   "Tariff" means any applicable federal or state tariff of a Party, or
standard agreement or other document that sets forth the generally available
terms and conditions under which a Party offers a particular service, facility,
or arrangement.

     1.69   "Technically Feasible Point" is As Described in the Act.

     1.70   "Telecommunications" is As Defined in the Act.

     1.71   " Telecommunications Act" means the Telecommunications Act of 1996 
and any rules and regulations promulgated thereunder.

     1.72   "Telecommunications Carrier" is As Defined in the Act.

     1.73   "Telecommunications Service" is As Defined in the Act.

     1.74   "Telephone Exchange Service," sometimes also referred to as 
"Exchange Service," is As Defined in the Act. Telephone Exchange Service 
generally provides the Customer with a telephonic connection to, and a unique 
telephone number address on, the public switched telecommunications network, and
enables such Customer to place or receive calls to all other stations on the 
public switched telecommunications network.

     1.75   "Toll Traffic" means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that Party's network and is not Local Traffic or Ancillary Traffic. Toll Traffic
may be either "IntraLATA Toll Traffic" or InterLATA Toll Traffic," depending on 
whether the originating and terminating points are within the same LATA.

     1.76   "Transit Traffic" means any traffic that originates from or
terminates at MFS's network, "transits" BA's network substantially unchanged,
and terminates to or originates from a third carrier's network, as the case may
be. "Transit Traffic Service" provides MFS with the ability to use its
connection to a BA Access Tandem Switch for the delivery of calls which
originate or terminate with MFS and terminate to or originate from a carrier
other than BA, such as another CLEC, a LEC other than BA, or a wireless carrier.
In these cases, neither the originating nor terminating Customer is a Customer
of BA. This Service is provided through BA's Access Tandem

                                       9
<PAGE>
 
Switches. "Transit Traffic" and "Transit Traffic Service" do not include or 
apply to traffic that is subject to an effective Meet-Point Billing arrangement.

     1.77   "Trunk Side" means a Central Office Switch connection that is 
capable of, and has been programmed to treat the circuit as, connecting to 
another switching entity (e.g. another carrier's network). Trunk Side 
                          - -   
connections offer those transmission and signaling features appropriate for the 
connection of switching entities.

     1.78   "Unbundled Local Loop Element" or "ULL" means a transmission path 
that extends from a Main Distribution Frame, DSX-panel, or functionally 
comparable piece of equipment in the Customer's serving End Office to the Rate 
Demarcation Point (or network interface device (NID) if installed) in or at a 
Customer's premises. The actual loop transmission facilities used to provide an 
ULL may utilize any of several technologies.

     1.79   "Verification with Call Interruption" or "VCI" means a service that 
may be requested and provided when Line Status Verification has determined that 
a line is busy due to an ongoing call. VCI is an operator interruption of that 
ongoing call to inform the called party that a calling party is seeking to 
complete his or her call to the called party.

     1.80   "Voice Grade" means either an analog signal of 300 to 3000 Hz or a
digital signal of 56/64 kilobits per second. When referring to digital voice 
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.81   "Wire Center" means a building or portion thereof in which a Party 
has the exclusive right of occupancy and which serves as a Routing Point for 
Switched Exchange Access Service.

2.0  INTERPRETATION AND CONSTRUCTION.

     2.1    All references to Sections, Exhibits and Schedules shall be deemed 
to be references to Sections of, and Exhibits and Schedules to, this Agreement 
unless the context shall otherwise require. The headings used in this Agreement
are inserted for convenience of reference only and are not intended to be a part
of or to affect the meaning of this Agreement. Unless the context shall 
otherwise require, any reference to any agreement, other instrument (including
BA or other third party offerings, guides or practices), statute, regulation,
rule or tariff is to such agreement, instrument, statute, regulation, or rule or
tariff as amended and supplemented from time to time (and, in the case of a
statute, regulation, rule or tariff, to any successor provision).

     2.2    Subject to the terms set forth in Section 20, each Party hereby 
incorporates by reference those provisions of its tariffs that govern the 
provision of any of the services or facilities provided hereunder. If any 
provision of this Agreement and an applicable tariff cannot be reasonably 
construed or interpreted to avoid conflict, the Parties agree to negotiate in 
good faith to reconcile and resolve such conflict. If any provision contained in
this main body of the Agreement and any Exhibit hereto cannot be reasonably 
construed or interpreted to avoid conflict, the

                                      10
<PAGE>
 
provision contained in this main body of the Agreement shall prevail. The fact 
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for 
finding, a conflict for purposes of this Section 2.

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1  Subject to the terms and conditions of this Agreement, each Party 
shall exercise its best efforts to adhere to the Interconnection Activation 
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to 
provide fully operational service predominantly over its own Telephone Exchange
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes
of this Agreement, MFS's service in Virginia shall be considered provided 
"predominantly over its own Telephone Exchange Service facilities" if MFS uses 
its own Central Office Switch(es) (as opposed to resale of another carrier's
Telephone Exchange Service or Ports) to serve the majority of its Telephone
Exchange Service Customers, its own interoffice transport facilities for the
majority of its interoffice transport needs, and its own local loops (or
functional equivalent), in addition to resale of other carriers' Telephone
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2  Schedule 3.0 may be revised and supplemented from time to time upon 
the mutual agreement of the Parties to reflect the intention of the Parties to 
interconnect in additional LATAs pursuant to subsection 4.4 by attaching one or 
more supplementary schedules to Schedule 3.0. The Parties stipulate and agree 
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act, and the requirements of
the Competitive Checklist, under Section 271 of the Act. MFS represents that it 
is, or intends to become, a provider of Telephone Exchange Service to 
residential and business subscribers offered exclusively over its own Telephone 
Exchange Service facilities or predominantly over its own Telephone Exchange 
Service facilities in combination with the resale of the Telecommunications 
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local 
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit 
Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to the terms
and conditions of this Agreement, Interconnection of the Parties facilities and 
equipment for the transmission and routing of Local Traffic and Toll Traffic 
pursuant to this Section 4 shall be established on or before the corresponding 
"Interconnection Activation Date" shown for each such LATA within Virginia on 
Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and supplemented
from time to time upon the mutual agreement of the Parties to reflect 
Interconnection in additional LATAs in Virginia pursuant to subsection 4.4 by 
attaching one or more supplementary addenda to such Schedules.

                                      11 
<PAGE>
 
     4.1  SCOPE

          4.1.1  Section 4 describes the architecture for Interconnection of the
Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct trunk groups:

          Traffic Exchange Trunks for the transmission and routing of
          -----------------------                                    
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251 (c)(2) of the Act, in accordance with Section 5 below:

          Access Toll Connecting Trunks for the transmission and routing of
          -----------------------------                                    
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Access Service via
          a BA Access Tandem, pursuant to Section 251 (c)(2) of the Act, in
          accordance with Section 6 below:

          Information Services Trunks for the transmission and routing of
          ---------------------------
          terminating Information Services Traffic in accordance with Section 7
          below:

          LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
          --------------                                                        
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating E91
          ---------------
          1/911 traffic, in accordance with Section 7 below:

          Directory Assistance Trunks for the transmission and routing of
          ---------------------------
          terminating directory assistance traffic, in accordance with
          subsection 19.4 below; and

          Operator services (call completion) Trunks for the transmission and 
          ------------------------------------------
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2  The SONET interconnection arrangement described in subsection
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA
Toll Traffic until such time as the Parties have agreed to appropriate
compensation arrangements relating to the exchange of other types of traffic
over such system, and (ii) subject to the Parties reaching agreement on an
appropriate compensation arrangement in the event either Party will be
providing or utilizing (in terms of minutes of use) significantly more than one-
half-of the SONET facility. Unless otherwise agreed to by the Parties, the SONET
system described herein shall not be used to exchange InterLATA Toll Traffic.
Until the SONET system has been established by the Parties in accordance with
subsection 4.3 and this subsection 4.1.2. the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
(IntraLATA and InterLATA) Traffic.

                                      12
<PAGE>
 
          4.1.3   To the extent required by Section 251 of the Act, the Parties 
represent that the arrangements provided in subsections 4.2 and 4.3 of this 
Agreement provide for Interconnection to each other's networks at any 
technically feasible point. For the purposes of this Agreement, the Parties 
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a Local
Serving Wire Center and/or other points as specified herein, and, in the case of
MFS, at a node or Central Office and/or other points as specified herein 
(collectively, the "Interconnection Points" or "IPs").

          4.1.4   The Parties shall establish physical interconnection points at
the available IPs at the locations designated in Schedule 4.0. The mutually 
agreed-upon IPs on the MFS network at which MFS will provide transport and 
termination of traffic shall be designated as the MFS Interconnection Points 
("M-IPs"); the mutually agreed-upon IPs on the BA network shall be designated as
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of 
charging for the transport of traffic from the BA-IP to the M-IP in any given 
LATA, the M-IP shall be no further than an entrance facility away from the 
BA-IP in such LATA. The Parties may by mutual agreement establish additional 
interconnection points at any technically feasible points consistent with the 
Act.

     4.2  PHYSICAL ARCHITECTURE.  In each LATA identified on Schedule 4.0, MFS 
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous 
Optical Network ("SONET") transmission system by which they shall interconnect 
their networks pursuant to the joint network reconfiguration and grooming plan 
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the 
following specifications:

          4.2.1   The SONET system shall be used to deliver appropriate traffic 
to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2   The SONET transmission system in each LATA shall be configured
substantially as illustrated in Schedule 4.2 and pursuant to the Joint Grooming 
Plan, or as otherwise mutually agreed. The Parties shall agree upon which Party 
or Parties shall be responsible for procuring, installing, and maintaining the 
agreed-upon Optical Line Terminating Multiplexor ("OLTM") equipment, fiber optic
facilities and other equipment pursuant to the Joint Grooming Plan, as 
illustrated in that Schedule.

          4.2.3   The physical interface of MFS's and BA's facilities necessary 
to effect SONET transmission shall be at the optical level via a Mid-Span Meet 
or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1   The Parties agree to provide initial interconnection 
arrangements utilizing electrical handoffs, substantially as illustrated in 
Schedule 4.3, for a period of no more than eighteen (18) months after the later 
of the Effective Date and the LATA Start Date set forth for the LATA in Schedule
3.0; provided, however, that such initial interconnection arrangements

                                      13

<PAGE>
 
shall continue until (i) facilities suitable for the SONET arrangements 
described in subsection 4.2 are established by each of the Parties in its own 
sole discretion in the LATA at the mutually agreed-upon SONET meet points and
made available, and (ii) the Parties have agreed upon fully compatible OLTM
equipment for use with such facilities.

          4.3.2  The Parties agree to utilize the M-IP and BA-IP in each LATA as
designated in Schedule 4.0 as the points from which each Party will provide the 
transport and termination of traffic.

          4.3.3  MFS shall provide its own facilities for the delivery of 
traffic to a collocation arrangement established at the BA-IP pursuant to
Section 13. Bell Atlantic shall provide transport and termination of the traffic
beyond the BA-IP.

          4.3.4  BA shall purchase an MFS entrance facility (and any necessary 
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the 
M-IP. Alternatively, BA may choose to provide its own facilities to a 
collocation arrangement established at the M-IP pursuant to Section 13. MFS 
shall provide transport and termination of the traffic beyond the M-IP.

          4.3.5  Under this initial architecture described in this subsection 
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5 
below and pursuant to the other Party's Switched Exchanged Access Service
tariffs. The other Party's Switched Exchanged Access Service rates shall apply
to such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.
     
     4.4      INTERCONNECTION IN ADDITIONAL LATAs

          4.4.1  If MFS determines to offer Telephone Exchange Services in any 
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange 
Services, MFS shall provide written notice to BA of the need to establish 
Interconnection in such LATA pursuant to this Agreement.

          4.4.2  The notice provided in subsection 4.4.1 shall include (i) the 
initial Routing Point MFS has designated in the New LATA: (ii) MFS's requested 
Interconnection Activation Date (and related milestone dates in accordance with 
the format in Schedule 3.0): and (iii) a non-binding forecast of MFS's trunking 
requirements.

          4.4.3  Unless otherwise agreed to by the Parties, the Parties shall 
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local 
Serving Wire Center that houses an Access Tandem Office within the LATA nearest 
to the M-IP (as measured in airline miles utilizing the V&H coordinates method)
as the BA-IP in that LATA, provided that, for the

                                      14




<PAGE>
 
purpose of charging for the transport of traffic from the BA-IP to the M-IP, the
M-IP shall be no further than an entrance facility away from the BA-IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to 
reflect the schedule applicable to each new LATA requested by MFS: provided, 
however, that unless agreed by the Parties, the Interconnection Activation Date 
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten 
(10) business days of BA's receipt of MFS's notice, BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by 
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party 
shall make available Interconnection Points and facilities for routing of 
traffic from those Interconnection Points as designated in Schedule 4.5. Any 
additional traffic that is not covered in Schedule 4.5 shall be subject to 
separate negotiations between the Parties, except that (i) either Party may 
deliver traffic of any type or character to the other Party for termination as 
long as the delivering Party pays the receiving Party's then current Switched 
Exchange Access rates for such traffic, and (ii) upon a bona fide request from 
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an 
agreement covering the exchange of such traffic.

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT
TO SECTION 251(C)(2)

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups
(the "Traffic Exchange Trunks") to be effected over the Interconnections
specified in Section 4.0 for the transmission and routing of Local Traffic and
IntraLATA Toll Traffic between the Parties, respective Telephone Exchange
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-1 level or higher 
for exchange of Local and Toll Traffic. Higher speed connections shall be made, 
when and where available, in accordance with the Joint Grooming Plan prescribed 
in Section 10. Ancillary Traffic trunk groups may be made below as DS-1 level, 
as may be agreed to by the Parties.

          5.2.2  Each Party will identify its Carrier Identification Code, a 
three or four digit numeric obtained from Bellcore, to the other Party when 
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

          5.3.1  For purposes of routing MFS traffic to BA the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own or other carriers' traffic. For purposes of routing
BA traffic to MFS, the subtending arrangements


                                      15
<PAGE>
 
between MFS Access Tandem Switches (or functional equivalent) and MFS End Office
Switches (or functional equivalent) shall be the same as the Access Tandem/End
Office subtending arrangements (or functional equivalent) which MFS maintains
for the routing of its own or other carriers' traffic.

     5.4  SIGNALING

     Each Party will provide the other Party with access to its databases and
associated signaling necessary for the routing and completion of the other 
Party's traffic in accordance with the provisions contained in Section 17
below.

     5.5  GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6  MEASUREMENT AND BILLING

        5.6.1  For billing purposes, each Party shall pass Calling Party Number
("CPN") information on each call carried over the Traffic Exchange Trunks,
wherever technically feasible. At such time as either Party has the ability, as
the Party receiving the traffic, to use such CPN information to classify on an
automated basis traffic delivered by the other Party as either Local Traffic or
Toll Traffic, such receiving Party shall bill the originating Party the Local
Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of Traffic for which CPN is
passed, as provided in Exhibit A and applicable Tariffs.

        5.6.2  If, under the circumstances set forth in subsection 5.6.1, it is
not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party
the Local Traffic termination rates. Intrastate Exchange Access rates, or
Interstate Exchange Access rates applicable to each minute of traffic, as
provided in Exhibit A and applicable Tariffs, for which CPN is passed. For the
remaining up to ten percent (10%) of calls without CPN information, the
receiving Party shall bill the originating Party for such traffic as Local
Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, in direct proportion to the minutes of use of
calls passed with CPN information.

        5.6.3  If it is not technically feasible for the originating Party to
pass CPN on more than ten percent (10%) of calls, or if the receiving Party
lacks the ability to use CPN information to classify on an automated basis
traffic delivered by the other Party as either Local Traffic or Toll Traffic,
and the originating Party chooses to combine Local and Toll Traffic on the same
trunk group, it will supply an auditable Percent Local Use ("PLU") report
quarterly, based on the previous three months' traffic, and applicable to the
following three months. If the originating Party also chooses to combine
Interstate and Intrastate Toll Traffic on the same trunk
          
                                      16

<PAGE>
 
group, it will supply an auditable Percent Interstate Use ("PIU") report 
quarterly, based on the previous three months' terminating traffic, and 
applicable to the following three months. In lieu of the foregoing PLU and/or 
PIU reports, the Parties may agree to provide and accept reasonable surrogate 
measures for an agreed-upon interim period.

          5.6.4  Measurement of billing minutes for purposes of determining 
terminating compensation shall be in conversation seconds.

     5.7  RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

     Reciprocal Compensation arrangements address the transport and termination 
of Local Traffic.  BA's delivery of Traffic to MFS that originated with a third 
carrier is addressed in subsection 7.3.  Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and termination of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

          5.7.1  Nothing in this Agreement shall be construed to limit either 
Party's ability to designate the areas within which that Party's Customers may 
make calls which that Party rates as "local" in its Customer Tariffs.

          5.7.2  The Parties shall compensate each other for transport and 
termination of Local Traffic in an equal and symmetrical manner at the rates 
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if 
not set forth therein, in the applicable Tariff(s) of the terminating Party, as 
the case may be. These rates are to be applied at the M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges,
including port or transport charges, shall apply for the termination of Local
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A.  
When Local Traffic is terminated over the same trunks as Toll Traffic, any port
or transport or other applicable access charges related to the Toll Traffic
shall be prorated to be applied only to the Toll Traffic.

          5.7.3  The Reciprocal Compensation arrangements set forth in this 
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs.

          5.7.4  Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5.

          5.7.5  The designation of Traffic as Local or Toll for purposes of 
compensation shall be based on the actual originating and terminating points of 
the complete end-to-end call, regardless of the carrier(s) involved in carrying 
any segment of the call.

                                      17
 
<PAGE>
 
          5.7.6  Each Party reserves the right to measure and audit all Traffic 
to ensure that proper rates are being applied appropriately. Each Party agrees 
to provide the necessary Traffic data or permit the other Party's recording 
equipment to be installed for sampling purposes in conjunction with any such 
audit.

          5.7.7  The Parties will engage in settlements of alternate-billed 
calls (e.g. collect, calling card, and third-party billed calls) originated or 
       - -
authorized by their respective Customers in Virginia in accordance with the 
terms of an appropriate billing services agreement for intraLATA intrastate 
alternate-billed calls or such other arrangement as may be agreed to by the 
Parties.

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2).

     6.1  SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over 
the Interconnections specified in Section 4 for the transmission and routing of 
traffic between MFS Telephone Exchange Service Customers and Interexchange 
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

        6.2.1  MFS shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from MFS's Customers.

        6.2.2  Access Toll Connecting Trunks shall be used solely for the 
transmission and routing of Exchange Access to allow MFS's Customers to connect 
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

        6.2.3  The Access Toll Connecting Trunks shall be two-way trunks 
connecting an End Office Switch MFS utilizes to provide Telephone Exchange 
Service and Switched Exchange Access in a given LATA to an Access Tandem BA 
utilizes to provide Exchange Access in such LATA.

        6.2.4  The Parties shall jointly determine which BA Access Tandem(s) 
will be subtended by each MFS End Office Switch.  MFS's End Office switch shall
subtend the BA Access Tandem that would have served the same rate center on BA's
network.  Alternative configurations will be discussed as part of the Joint 
Plan.

     6.3  MEET-POINT BILLING ARRANGEMENTS

                                      18

<PAGE>
 
          6.3.1  MFS and BA will establish Meet-Point Billing arrangements in 
order to provide a common transport option to Switched Access Services Customers
via an Access Tandem Switch in accordance with the Meet-Point Billing guidelines
contained in the OBF's MECAB and MECOD documents, except as modified herein, and
BA's Virginia Tariff Number 217, Section 2.4.8.  The arrangements described in 
this Section 6 are intended to be used to provide Switched Exchange Access 
Service that originates and/or terminates on a Telephone Exchange Service that 
is provided by either Party, where the transport component of the Switched 
Exchange Access Service is routed through a Tandem Switch that is provided by 
BA.

          6.3.2  In each LATA, the Parties shall establish MPB arrangements 
between the applicable Rating Point/BA Local Serving Wire Center combinations.

          6.3.3  Interconnection for the MPB arrangement shall occur at the 
BA-IP in the LATA, unless otherwise agreed to by the Parties.

          6.3.4  MFS and BA will use reasonable efforts, individually and 
collectively, to maintain provisions in their respective state access tariffs, 
and or provisions within the National Exchange Carrier Association ("NECA") 
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

          6.3.5  Each Party shall implement the "Multiple Bill/Single Tariff" or
"Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an IXC 
for the portion of the jointly provided telecommunications service provided by 
that Party.

          6.3.6  The rate elements to be billed by each Party are as set forth 
in Schedule 6.3.  The actual rate values for each Party's affected access 
service rate element shall be the rates contained in that Party's own effective 
federal and state access tariffs, or other document that contains the terms 
under which that Party's access services are offered.  The MPB billing 
percentages for each Rating Point/BA Local Serving Wire Center combination shall
be calculated in accordance with the formula set forth in subsection 6.3.16 
below.

          6.3.7  Each Party shall provide the other Party with the billing name,
billing address, and Carrier Identification Code ("CIC") of the IXC, and 
Identification of the IXC's Local Serving Wire Center in order to comply with 
the MPB notification process as outlined in the MECAB document via facsimile or 
such other media as the Parties may agree to.

          6.3.8  BA shall provide MFS with the Switched Access Detail Usage Data
(category 1101XX records) on magnetic tape or via such other media as the 
Parties may agree to, no later than ten (10) business days after the date the 
usage occurred.

          6.3.9  MFS shall provide BA with the Switched Access Summary Usage 
Data (category 1150XX records) on magnetic tape or via such other media as the 
Parties may agree, no later than ten (10) business days after the date of its 
rendering of the bill to the relevant IXC, which bill shall be rendered no less 
frequently than monthly.

                                      19

<PAGE>
 
          6.3.10 Each Party shall coordinate and exchange the billing account 
reference ("BAR") and billing account cross reference ("BACR") numbers or 
Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each Party 
shall notify the other if the level of billing or other BAR/BACR elements 
change, resulting in a new BAR BACR number, or if the OCN changes.

          6.3.11. Errors may be discovered by MFS, the IXC or BA. Each Party 
agrees to provide the other Party with notification of any errors it discovers 
within two (2) business days of the date of such discovery. In the event of a 
loss of data, both Parties shall cooperate to reconstruct the lost data and, if 
such reconstruction is not possible, shall accept a reasonable estimate of the 
lost data based upon prior usage data.

          6.3.12  Either Party may request a review or audit of the various
components of access recording up to a maximum of two (2) audits per calender
year. All costs associated with each review and audit shall be borne by the
requesting Party. Such review or audit shall be conducted subject to
confidentiality protection and during regular business hours. A Party may
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

          6.3.13. Nothing contained in this subsection 6.3. shall create any 
liability for damages, losses, claims, costs, injuries, expenses or other 
liabilities whatsoever on the part of either Party (other than as may be set 
forth in MECAB or in any applicable Tariff).

          6.3.14. The Parties shall not charge one another for the services 
rendered or information provided pursuant to this subsection 6.3.

          6.3.15  MPB will apply for all traffic bearing the 500, 900 800/888 
(to the extent provided by an IXC) or any other non-geographic NPA which may be 
likewise designated for such traffic in the future.

          6.3.16  In the event MFS determines to offer Telephone Exchange 
Services in another LATA in which BA operates an Access Tandem Switch, BA shall 
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for 
the BA End Offices in the area where the MFS Rating Point(s) associated with 
the NPA-NXX(s) to from which the Switched Exchange Access Services are homed. 
The MPB billing percentages for each new Rating Point/BA Local Serving Wire 
Center combination shall be calculated according to the following formula:

                      a/(a + b) = MFS Billing Percentage
                                      and
                       b/(a +b) = BA Billing Percentage

               where:
               -----

               a = the airline mileage between the Rating Point and the actual 
          point of interconnection for the MPB arrangement: and

                                      20
<PAGE>
 
                b = the airline mileage between the BA Local Serving Wire Center
          and the actual point of interconnection for the MPB arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange 
Services and its calculation of the billing percentages which should apply for 
such arrangement, as part of the notice required by subsection 4.4.1 above. 
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS
shall confirm the new Rating Point/BA Local Serving Wire Center combination and
billing percentages. Nothing in this subsection 6.3.16 shall be construed to
limit MFS's ability to select to interconnect with BA in additional LATAs by
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

     6.4  800/888 TRAFFIC

     The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

          6.4.1.  When MFS delivers untranslated 800/888 calls to BA for 
completion.

                  (a) to an IXC, BA shall:

                      (i)   Provide a MPB record in an industry standard format
                      to MFS; and

                      (ii)  Bill the IXC the appropriate BA query charge 
                      associated with the call.

                  (b) as an IntraLATA call to BA or another LEC in the LATA. BA
shall

                      (i)   Provide a copy record in an industry standard format
                      to MFS:

                      (ii)  Bill MFS the appropriate BA query charge associated
                      with the call; and

                      (iii) Submit the call records to IIORP for payment by BA 
                      or the LEC that is the 800/888 service provider of MFS's 
                      and any intermediate LEC's Tariffed Exchange Access
                      charges and query charges.

          6.4.2   When BA delivers 800/888 calls originated by BA's or another 
LEC's Customers to MFS for completion

                                      21
<PAGE>
 
               (a) to MFS in its capacity as an IXC, BA shall:

                   (i)  Bill MFS the appropriate BA query charge associated with
                   the call; and

                   (ii) Bill MFS the appropriate FGD Exchange Access charges 
                   associated with the call.

               (b) as an IntraLATA call to MFS in its capacity as a LEC,

                   (i)  BA shall submit the appropriate call records to ITORP
                   for payment by MFS of BA's (and another LEC's, if
                   appropriate) Tariffed Exchange Access charges; and

                   (ii) MFS shall pay the originating LEC's appropriate query 
                   charge associated with the call.


7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to MFS-originated Information 
Services Traffic directed to an information services platform connected to BA's 
network. At such time as MFS connects Information Services platforms to its 
network, the Parties shall agree upon a suitable arrangement for BA-originated
Information Services Traffic.

          7.1.1  MFS shall route Information Services Traffic that originates on
its own network to the appropriate information services platform(s) connected to
BA's network. MFS will establish a dedicated trunk group to the BA information 
services serving switch. This trunk group will be utilized to allow MFS to route
information service traffic originated on its network to BA.

          7.1.2  MFS shall provide an electronic file transfer or monthly 
magnetic tape containing recorded call detail information to BA.

          7.1.3  BA shall provide to MFS via electronic file transfer or 
magnetic tape or other means as available all necessary information to rate the 
Information Services Traffic to MFS's Customers pursuant to the BA's agreements 
with each information services provider. Information shall be provided in as 
timely a fashion as practical in order to facilitate record review and reflect 
actual prices set by the individual information services providers.

          7.1.4  MFS shall bill and collect such information services provider 
charges and remit the amounts collected to BA less:

                                      22






<PAGE>
 
          (a)   The Information Services Billing and Collection fee set forth in
     Exhibit A: and

          (b)   An uncollectibles reserve calculated based on the
     uncollectibles reserve in BA's billing and collection agreement with the
     applicable information services provider; and

          (c)   Customer adjustments provided by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and 
Customer adjustments to allow BA to pass through the adjustments to the 
information services provider, and BA shall pass through such adjustments. 
However, if the information services provider disputes such adjustments and 
refuses to accept such adjustments. MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputes adjustments shall be solely
between MFS and the information services provider.

          7.1.5 Nothing in this Agreement shall restrict either Party from 
offering to its Telephone Exchange Service Customers the ability to block the 
completion of Information Service Traffic.

          7.1.6 The Parties may agree to separate arrangements for the billing 
and compensation of variable rated (e.g. 970,540) information services.
                                    - -
  
          7.1.7 The Information Services Traffic addressed herein does not 
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1 Each Party shall offer LSV and VCI services to enable its 
Customers to verify and/or interrupt calls of the other Party's Customers. In 
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party 
(Party A) and the responding Party (Party B) shall perform in accordance with 
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to 
be agreed upon between the Parties.

          7.2.2 The Party B operator shall only verify the status of the line 
(LSV) or interrupt the line to inform the called party that there is a call 
waiting. The Party B operator will not complete the telephone call of the 
Customer initiating the LSV VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable 
charges apply whether or not the called party releases the line.

          7.2.3 Each Party's operator bureau shall accept LSV and VCI inquiries 
from the operator bureau of the other Party in order to allow transparent 
provision of LSV/VCI Traffic between the Parties' networks.


                                      23
<PAGE>
 
          7.2.4  Each Party shall route LSV/VCI Traffic inquires over separate 
direct trunks (and not the Local/IntraLATA, InterLATA Trunks) established 
between the Parties' respective operator bureaus. Each Party shall offer 
interconnection for LSV/VCI traffic at its Local Serving Wire Center, operator 
services Tandem Office subtended by such Local Serving Wire Center, or other 
mutually agreed point in the LATA. Separate LSV VCI trunks delivered at the 
Local Serving Wire Center will be directed to the operator services Tandem 
Office designated by Party B. Unless otherwise mutually agreed, the Parties 
shall configure LSV/VCI trunks over the Interconnection architectures in 
accordance with the terms of Section 4, consistent with the Joint Grooming Plan.
Party A shall outpulse the appropriate NPA, ATC Code, and Routing Code (operator
code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a 
reciprocal local traffic exchange arrangement (either via written agreement or 
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it 
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as 
quickly as commercially reasonable following the Effective Date and to provide 
copies thereof to BA, but continues to utilize BA's Transit Service for the 
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC, 
MFS shall, in addition to paying the rate set forth in Exhibit A for said 
Transit Service, pay BA any charges or costs such terminating third party 
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred by 
                                       ----
BA in delivering or terminating such Traffic and/or resulting from MFS's failure
to secure said reciprocal local traffic exchange arrangement. BA will, upon 
request, provide MFS with all reasonable cooperation and assistance in obtaining
such arrangements. The Parties agree to work cooperatively in appropriate 
industry fora to promote the adoption of reasonable industry guidelines relating
to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in 
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will 
deliver each call to each involved network with CCS and the appropriate 
Transactional Capabilities Application Part ("TCAP") message to facilitate full 
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and 
exchange records between the Parties and with the terminating carrier to 
facilitate the billing process to the original network.

          7.3.4  Transit Traffic shall be routed over the Traffic Exchange 
Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

                                      24

<PAGE>
 
          7.4.1   MFS will interconnect to the BA 911 E911 selective routers or 
911 Tandem Offices, where available, which serve the areas in which MFS provides
Telephone Exchange Services, for the provision of 911 E911 services and for 
access to all subtending Public Safety Answering Points ("PSAP"). In such 
situations, BA will provide MFS with the appropriate CLLI codes and 
specifications of the Tandem Office serving area. In areas where E911 is not 
available, MFS and BA will negotiate arrangements to connect MFS to the 911 
service.

          7.4.2   Path and route diverse interconnections for 911 E911 shall be 
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed, 
and as required by law or regulation.

          7.4.3   Upon request, BA will provide MFS with the following:

          (a)     an electronic interface, when available, through which MFS
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911
     information such as name, address, and telephone number in writing for BA's
     entry into the 911 database system. Any 911-related data exchanged between
     the Parties shall conform to the National Emergency Number Association
     standards:

          (b)     a file containing the Master Street Address Guide ("MSAG"), as
     may be updated from time to time, for the exchanges or communities
     specified;

          (c)     a return of any MFS E911 data entry files containing errors, 
     so that MFS may ensure the accuracy of the Customer records; and

          (d)     PSAP 911 Tandem information.

          7.4.4   In cases where a Customer of one Party elects to discontinue
     its service and become the Customer of the other Party ("Party B") but
     desires to retain its original telephone number pursuant to an INP or PNP
     arrangement, Party B will outpulse the telephone number to which the call
     has been forwarded (i.e. the Customer's ANI) to the 911 Tandem Office.
                         - -
     Party B will also provide the 911 database with both the forwarded number
     and the directory number, as well as the appropriate address information of
     the Customer.

          7.4.5   BA and MFS will use their best efforts to facilitate the
     prompt, robust, reliable and efficient interconnection of MFS systems to
     the 911 E911 platforms.

          7.4.6   BA and MFS will work cooperatively to arrange meetings with 
PSAPs to answer any technical questions the PSAPs, or county or municipal 
coordinators may have regarding the 911 E911 arrangements. BA shall assist MFS 
in identifying the appropriate person in each municipality for the purpose of 
obtaining the ten-digit subscriber number of each PSAP.

                                      25

<PAGE>
 
          7.4.7   The Parties acknowledge that the provision of INP, until PNP 
with full 911 compatability is available, creates a special need to have the 
Automatic Location Identification ("ALI") screen reflect two number: the "old" 
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification 
("TCI") of the company that provides service to the calling line as part of the 
ALI display. Until such time as TCI is operational, however, BA and MFS agree to
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8   MFS will compensate BA for connections to its 911/E911 
pursuant to Exhibit A.

          7.4.9   MFS will comply with all applicable rules and regulations 
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY  Ancillary Traffic that may be terminated
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be 
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise 
adversely affect in any manner either Party's right to employ or to request and 
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code 
Assignment Guidelines, as may be amended from time to time, or to establish, by 
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX 
codes. Until such time as number administration is provided by a third party, BA
shall provide MFS access to telephone numbers by assigning NXX codes to MFS in 
accordance with such Assignment Guidelines.


     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing 
Guide ("LERG") in order to recognize and route traffic to the other Party's 
assigned NXX codes at all times. Neither Party shall impose any fees or charges 
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, MFS shall 
adopt the Rate Center Areas and Rate Center Points that the Commission has 
approved for BA, in all areas where BA and MFS service areas overlap, and MFS 
shall assign whole NPA-NXX codes to each Rate Center unless the LEC industry 
adopts alternative methods of utilizing NXXs in the manner adopted by the NANP.

                                      26

<PAGE>
 
     8.4  MFS will also designate a Routing Point for each assigned NXX code. 
MFS shall designate one location for each Rate Center Area as the Routing Point 
for the NPA-NXXs associated with that Area, and such Routing Point shall be 
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in 
this Agreement is intended to, and nothing in this Agreement shall be construed 
to, in any way constrain MFS's choices regarding the size of the local calling 
area(s) that MFS may establish for its Customers, which local calling areas may 
be larger than, smaller than, or identical to, BA's local calling areas.


9.0  NETWORK MAINTENANCE AND MANAGEMENT: OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance 
                                                           - -
contact numbers, network information, information required to comply with law 
enforcement and other security agencies of the Government) to achieve this 
desired reliability. In addition, the Parties will work cooperatively to apply 
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that 
may be agreed to between the Parties and to employ characteristics and methods 
of operation that will not interfere with or impair the service or any 
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of 
operation used by Party B will or may interfere with or impair its provision of 
services. Party A shall have the right to discontinue Interconnection subject, 
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days' prior written 
notice of interference or impairment or potential interference or impairment 
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice 
provided to Party B under (a) above to the appropriate federal and/or state 
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall 
not be required in emergencies and Party A may immediately discontinue 
Interconnection if reasonably necessary to meet its obligations. In such case, 
however, Party A shall use all reasonable means to notify Party B and the 
appropriate federal and or state regulatory bodies.

                                      27

<PAGE>
 
          9.3.4     Upon correction of the interference or impairment, Party A 
will promptly renew the Interconnection. During such period of discontinuance, 
there will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

          9.4.1     The Interconnection provided hereunder may be discontinued
by either Party upon thirty (30) days written notice to the other for repeated
or willful violation of and/or a refusal to comply with this Agreement. The
Party discontinuing will notify the appropriate federal and/or state regulatory
bodies concurrently with the notice to the other Party of the prospective
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or 
service being provided by a Party hereunder, the providing Party will follow 
procedures for isolating and clearing the outage or trouble that are no less 
favorable than those that apply to comparable arrangements, facilities, or 
services being provided by the providing Party to any other carrier whose 
network is connected to that of the providing Party. MFS and BA may agree to 
modify those procedures from time to time based on their experience with 
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES--SECTION 251(C)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN. On or before December
1, 1996, unless the Parties agree to a different date, MFS and BA shall jointly 
develop a grooming plan (the "Joint Plan") which shall define and detail, inter 
                                                                          -----
alia.
- ----

          (a)  modifications to the agreement on physical architecture 
     consistent with the guidelines defined in Section 4;

          (b)  standards to ensure that Interconnection trunk groups experience 
a grade of service, availability and quality which is comparable to that 
achieved on interoffice trunks within BA's network and in accord with all 
appropriate relevant industry-accepted quality, reliability and availability 
standards. Trunks provided by either Party for Interconnection services will be 
engineered using a design blocking objective of B.01;

                                      28
<PAGE>
 
          (c) the respective duties and responsibilities of the Parties with
respect to the administration and maintenance of the trunk groups, including,
but not limited to, standards and procedures for notification and discoveries of
trunk disconnects;

          (d)  disaster recovery provision escalations;

          (e) migration from one-way to two-way Interconnection Trunks upon
mutual agreement of the Parties;

          (f)  actual meet point locations on the SONET system; and

          (g)  such other matters as the Parties may agree;


     10.2 INSTALLATION REQUIREMENTS FOR TRUNK PROVISIONING. BA's standard 
intervals for Feature Group D Switched Exchange Access Services will be used for
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of its facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its 
inability to do so and will negotiate such intervals in good faith. The Parties 
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than 
those applicable to comparable arrangements, facilities, or services being 
provided by such Party to any other carrier whose network is connected to that 
of the providing Party.

     10.3 FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING. Within sixty (60) 
days of executing this Agreement, MFS shall provide BA a one (1) year traffic 
forecast. This initial forecast will provide the amount of traffic to be 
delivered to each of BA's End Offices affected by the exchange of traffic. The 
forecast shall be updated and provided to BA on a quarterly basis, and include 
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator 
services, 911, etc.), code (identifies trunk group). A location/Z location 
(CLLI codes), interface type (e.g, DS1), and trunks in service each year 
(cumulative).

          10.3 Initial Forecasts/Trunking Requirements. Because BA's trunking
               ---------------------------------------
requirements will, at least during period, be dependent on the customer segments
and service segments within customer segments to whom MFS decides to market its
services, BA will be largely dependent on MFS to provide accurate trunk
forecasts for both inbound (from BA) and outbound (from MFS) traffic. BA will,
as an initial matter and upon request, provide the same number of trunks to
terminate local traffic to MFS as MFS provides to terminate local traffic to BA,
unless MFS expressly identifies particular situations that are expected to
produce traffic that is substantially skewed in either the inbound or outbound
direction, in which case BA will provide the number of trunks MFS suggests. Upon
the establishment of any new set of trunks for traffic from BA to MFS, BA will
monitor traffic for ninety (90) days, and will, as necessary at the end of that
period, either augment trunks or disconnect trunks , based on the application of
reasonable engineering criteria to the actual traffic volume experienced. If,
after such 90-day period, BA has determined that the trunks are not warranted by
actual traffic volumes, then, on ten (10) days written notice, BA may hold MFS
financially responsible for

                                      29
BA-VA/MFS-VA (July 16, 1996) (Revised as of 07/29/97)

          


     
<PAGE>
 
such trunks retroactive to the start of the 90-day period until such time as 
they are justified by actual traffic volumes, based on the application of 
reasonable engineering criteria. To the extent that BA requires MFS to install 
trunks for delivery of traffic to BA, MFS may apply the same procedures with
respect to BA's trunking requirements.

11.0      UNBUNDLED ACCESS--SECTION 251(c)(3).

          To the extent required of each Party by Section 251 of the Act, each
Party shall offer to the other Party nondiscriminatory access to Network
Elements on an unbundled basis at any technically feasible point. BA shall
unbundle and separately price and offer Network Elements such that MFS will be
able to lease and interconnect to whichever of the Network Elements MFS 
requires, and to combine the BA-provided elements with any facilities and 
services that MFS may itself provide, except that MFS shall not recombine 
Network Elements purchased from BA for use as a substitute for the purchase at 
wholesale rates of Telecommunications Services that BA provides unless 
otherwise mandated by the FCC or the Commission or agreed to by BA with other 
carriers.

          11.1   UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

          Subject to subsection 11.4, BA shall allow MFS to access the following
ULL types (in addition to those ULLs available under applicable tariffs) 
unbundled from local switching and local transport in accordance with the terms 
and conditions set forth in this subsection 11.1.

                 11.1.1  "2-Wire Analog Voice Grades ULL" or "Analog 2W" 
provides an effective 2-wire channel with 2-wire interfaces at each end that is 
suitable for the transport of analog voice grade (nominal 300 to 3000 Hz) 
signals and loop-start signaling.  The service is more fully described in Bell 
Atlantic TR-72565.  If "Customer-Specified Signaling" is requested, the service 
will operate with one of the following signaling types that may be specified 
when the service is ordered: loop-start, ground-start, loop-reverse-battery, 
and no signaling. The service is more fully described in Bell Atlantic TR-72570.

                 11.1.2  "4-Wire Analog Grade ULL" or "Analog 4W provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The 
service will operate with one of the following signaling types that may be 
specified when the service is ordered: loop-start, ground-start, 
loop-reverse-battery, duplex, and no signaling. The service is more fully 
described in Bell Atlantic TR-72570.

                 11.1.3  "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides 
a channel with 2-wire interfaces at each end that is suitable for the transport 
of 160 kbps digital services using the ISDN 2B1Q line code.

                 11.1.4  "2-Wire ADSL-Compatible ULL" or "ADSL. 2W" provides a 
channel with 2-wire interfaces at each end that is suitable for the transport of
digital signals up to 6Mbps toward the Customer and up to 640 kbps from the 
Customer. BA will offer ADSL-Compatible

                                      30

  

<PAGE>
 
ULLs only when the technology BA uses to provide such ULLs is compatible with 
that of MFS. In addition, ADSL-Compatible ULLs will be available only where 
existing copper facilities can meet applicable industry standards.

          11.1.5  "2-Wire HDSL-Compatible ULL" or "HDSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of 784 
kbps digital signals simultaneously in both directions using the 2B1Q line code.
HDSL compatible ULLs will be available only where existing copper facilities can
meet the specifications.

          11.1.6  "4-Wire HDSL-Compatible ULL" or "HDSL 4W" provides a channel 
with 4-wire interfaces at each end. Each 2-wire channel is suitable for the 
transport of 784 kbps digital signals simultaneously in both directions using 
the 2B1Q line code. HDSL compatible ULLs will be available only where existing 
copper facilities can meet the specifications.

          11.1.7  ULLs will be offered on the terms and conditions specified 
herein and on such other terms in applicable Tariffs that are not inconsistent 
with the terms and conditions set forth herein. BA shall make ULLs available to 
MFS at the rates specified by the Commission, as amended from time to time, 
subject to the provisions of subsection 11.1.8 below.

          11.1.8  BA will make Analog 2-Wire ULLs available for lease by MFS in
accordance with the schedule set forth in Schedule 3.0. BA will make BRI ISDN
and Analog 4W ULLs available for lease by MFS by the later of January 1, 1997,
or the date when the ULL milestone contained in Schedule 3.0 is achieved in the
LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease by MFS
as soon as practicable, but in any event no later than six months, after BA
makes the services using equivalent loop facilities commercially available to
its own end-user Customers in Virginia. Upon request by either BA or MFS, the
Parties shall agree upon a reasonable schedule and location for a technical and
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s)
may, by mutual agreement, be conducted in any jurisdiction in which affiliates
of BA and MFS both operate. Upon successful completion of such trial(s), the
Parties shall agree upon an implementation schedule for the ULL type(s) subject
to such trial(s), which schedule shall begin no later than ninety (90) days
after successful completion of such trial(s).

     11.2  PORT TYPES

     BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.
                                            ---- ----

                                      31
 









 

       
<PAGE>
 
    11.3  TRUNK SIDE LOCAL TRANSPORT 

    BA shall provide MFS local transport from the trunk side of BA's Central
Office Switches using private lines and special access services unbundled from
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

    11.4  LIMITATIONS ON UNBUNDLED ACCESS

          11.4.1    Unless otherwise mandated by the FCC or the Commission or 
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under 
applicable tariffs.

          11.4.2    BA shall only be required to make available ULLs and Ports 
where such ULLs and Ports are available.

          11.4.3    MFS shall access BA's unbundled Network Elements 
specifically identified in this Agreement via Collocation in accordance with 
Section 13 at the BA Wire Center where those elements exist and each ULL or Port
shall be delivered to MFS's Collocation by means of a Cross Connection.

          11.4.4    BA shall provide MFS access to its Unbundled Local Loops at 
each of BA's Wire Centers for loops terminating in that Wire Center. In 
addition, if MFS requests one or more ULLs provisioned via Integrated Digital 
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA 
shall, where available, move the requested ULL(s) to a spare, existing physical
ULL at no additional charge to MFS. If, however, no spare physical ULL is 
available, BA shall within three (3) business days of MFS's request notify MFS 
of the lack of available facilities. MFS may then at its discretion make a 
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop 
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the
ULL concentration site point. Alternatively, MFS may choose to avail itself of
BA's Special Construction services, as set forth in Exhibit A, for the
provisioning of such ULL(s). Notwithstanding anything to the contrary in this
Agreement, the provisioning intervals set forth in subsection 11.6 and the
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this
subsection 11.4.4.

          11.4.5    If MFS orders a ULL type and the distance requested on such 
ULL exceeds the transmission characteristics in applicable technical references,
distance extensions may be required and additional rates and charges shall 
apply as set forth in Exhibit A or applicable Tariffs. 

          11.4.6    BA will exercise all reasonable efforts to ensure that the 
service intervals that apply to ULLs and unbundled Ports are comparable to the 
(i) repair intervals that apply to the bundled dial tone line service, and (ii) 
installation intervals that apply to other BA-

                                      32

<PAGE>
 
coordinated services, except as provided in Section 27. Although BA will make 
commercially reasonable efforts to ensure that ULLs and unbundled ports meet 
specified or agreed-upon technical standards. BA makes no warranty that the ULLs
or unbundled Ports supplied by BA hereunder will be compatible with the services
MFS may offer to its Customers if they are used in a manner not contemplated by
the Parties.

     11.5  AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

           11.5.1  BA shall, upon request of MFS, and to the extent technically 
feasible, provide to MFS access to its Network Elements on an unbundled basis 
for the provision of MFS's Telecommunications Service. Any request by MFS for 
access to an BA Network Element that is not already available shall be treated 
as a Network Element Bona Fide Request. MFS shall provide BA access to its 
Network Elements as mutually agreed by the Parties or as required by the 
Commission or FCC.

          11.5.2   A Network Element obtained by one Party from the other Party 
under this subsection 11.5 may be used in combination with the facilities of the
requesting Party only to provide a Telecommunications Service, including 
obtaining billing and collection, transmission, and routing of the 
Telecommunications Service.

          11.5.3  Notwithstanding anything to the contrary in this subsection 
11.5, a Party shall not be required to provide a proprietary Network Element to 
the other Party under this subsection 11.5 except as required by the Commission 
or FCC.

     11.6 PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs. These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA 
to MFS and from MFS to BA.

          11.6.1  Upon request by MFS, BA will apply the following coordination 
procedures to conversions of live Telephone Exchange Services to ULLs. 
Coordinated cutover charges will apply to any such arrangement, only to the 
extent provided by Section A.4.a of Exhibit A. If MFS elects not to request 
coordinated cutover, BA will process MFS's request in the normal course and 
subject to the normal installation intervals.

          11.6.2  MFS shall request ULLs from BA by delivering to BA a valid 
electronic transmittal service order (when available) or another mutually 
agreed-upon type of service order. Such service order shall be provided in 
accordance with industry format and specifications or such format and 
specifications as may be agreed to by the Parties. Within forty-eight (48) hours
of BA's receipt of such valid service order, BA shall provide MFS the firm order
commitment date according to the Performance Interval Dates set forth in
Schedule 27 by which the ULLs covered by such service order will be installed.
In addition, BA shall provide MFS with the related ULL design information, if
available, at least forty eight (48) hours prior to the scheduled cutover time.

                                      33

<PAGE>
 
          11.6.3    On each ULL order in a Wire Center, MFS and BA will agree on
a cutover time at least forty eight (48) hours before that cutover time. The
cutover time will be defined as a 15-30 minute window within which both the MFS
and BA personnel will make telephone contact to complete the cutover.
     
          11.6.4    Within the appointed 15-30 minute cutover time, the MFS
person will call the BA organization designated to coordinate cross-connection
work and when the BA organization is reached in that interval such work will be
promptly performed.

          11.6.5    If MFS requires a change in scheduling, it must contact BA
to issue a supplement to the original order. The negotiations process to
determine the date and time of cutover will then be reinitiated as usual.

          11.6.6    If the MFS person is not ready within the appointed interval
and if MFS had not called to reschedule the work at least two (2) hours prior to
the start of the interval. MFS shall be liable for the non-recurring charge for
the unbundled elements scheduled for the missed appointment. In addition, non-
recurring charges for the rescheduled appointment will apply.

          11.6.7    If BA is not available or not ready at any time during the
appointed 15-30 minute interval, MFS and BA will reschedule and BA will waive
the non-recurring charge for the unbundled elements originally scheduled for 
that interval, whenever those unbundled elements are actually cut over pursuant
to an agreed-upon rescheduling.

          11.6.8    The standard time expected from disconnection of a live
Telephone Exchange Service to the connection of the unbundled element to the MFS
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all
orders consisting of fifteen (15) ULLs or less. Orders involving more than
fifteen (15) ULLs will require a negotiated interval.

          11.6.9    If unusual or unexpected circumstances prolong or extend the
time required to accomplish the coordinated cutover, the Party responsible for
such circumstances is responsible for the reasonable labor charges of the Party.
Delays caused by the Customer are the responsibility of MFS.

          11.6.10   If MFS has ordered INP as part of an ULL installation, BA
will coordinate implementation of INP with the ULL installation. BA's provision
of unbundled elements shall in all cases be subject to the availability of
suitable facilities, to the extent permitted by Section 251 of the Act.

          11.6.11   If MFS requests or approves a BA technician to perform
services on the network side of the Rate Demarcation Point beyond normal
installation of the ULLs covered by the service order, BA may charge MFS for any
additional and reasonable labor charges to perform such services. BA may also
charge MFS its normal overtime rates for services MFS requests to be performed
outside of BA's normal business hours (MF 9am to 5pm. E.S.T.).

                                      34

<PAGE>
 
          11.7      MAINTENANCE OF UNBUNDLED LOCAL LOOPS

          If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a
dispatch, (iii) BA dispatches a technician, and (iv) such trouble was not caused
by BA's facilities or equipment, then MFS shall pay BA a per-trip charge charge
and labor charges per quater hour increments for time associated with said
dispatch, as set forth in Exhibit A. In addition this charge also applies in
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA with appropriate dispatch information based on their test results.
If, as the result of MFS instructions. BA is erroneously requested to dispatch
within the Central Office. BA may levy on MFS an appropriate charge.

          11.8      RATES AND CHARGES

          BA shall charge the non-recurring and monthly recurring rates for
unbundled Local Loops and other Network Elements set forth in Exhibit A.


12.0      RESALE--SECTIONS 251(C)(4) AND 251(B)(1).

          12.1      AVAILABILITY OF RETAIL RATES FOR RESALE

          Each Party shall make available its Telecommunications Services for 
resale at the retail rates set forth in its Tariffs to the other Party in 
accordance with Section 251(b)(1) of the Act. In addition, BA and MFS shall each
allow the resale by the other of all Telecommunications Services that are 
offered primarily or entirely to other Telecommunications Carriers (e.g.,
                                                                    - -  
Switched and special Exchange Access Services) at the rates already applicable 
to such services. BA shall also allow the resale by MFS of such other 
non-Telecommunications Services as BA, in its sole discretion, determines to 
provide for resale under terms and conditions to be agreed to by the Parties.

          12.2      AVAILABILITY OF WHOLESALE RATES FOR RESALE

          BA shall make available to MFS for resale all Telecommunications 
Services that BA provides at retail to Customers that are not Telecommunications
Carriers at the retail prices set forth in BA's Tariffs less the wholesale 
discount set forth in Exhibit A in accordance with Section 251(c)(4) of the Act.
Such services shall be provided in accordance with the terms of the applicable 
retail services Tariff(s), including, without limitation, user or user group 
restrictions, as the case may be, subject to the requirement that such 
restrictions shall in all cases comply with the requirements of Section 251 of 
the Act and the FCC Regulations regarding restrictions on resale. The Parties
may also agree to negotiate term and or volume discounts for resold services.

          12.3      AVAILABILITY OF SUPPORT SERVICES AND BRANDING FOR RESALE

                                      35

<PAGE>
 
     BA shall make available to MFS the various support services for resale 
described in Schedule 12.3 hereto in accordance with the terms set forth 
therein. In addition, to the extent required by Applicable Lawss, upon request 
by MFS and at prices, terms and conditions to be negotiated by MFS and BA, BA 
shall provide BA Retail Telecommunications Services (as defined in Schedule 
12.3) that are identified by MFS's trade name, or that are not identified by 
trade name, trademark, or service mark.

     12.4 ADDITIONAL TERMS GOVERNING RESALE AND USE OF BA SERVICES

          12.4.1 MFS shall comply with the provisions of this Agreement 
(including, but not limited to, all applicable BA Tariffs) regarding resale or
use of BA services. In addition, MFS shall make reasonable efforts in good faith
to ensure that its Customers comply with the provisions of BA's Tariffs
applicable to their use of BA's Telecommunications Services.

          12.4.2 Without in any way limiting subsection 12.4.1, MFS shall not 
resell (a) residential service to business or other nonresidential Customers of
MFS, (b) Lifeline or other means-tested service offerings, or grandfathered 
service offerings, to persons not eligible to subscribe to such service 
offerings from BA, or (c) any other BA service in violation of any user or user 
group restriction that may be contained in the BA Tariff applicable to such 
service to the extent such restriction is not prohibited by Applicable Lawss. In
addition, MFS shall be subject to the same limitations that BA's own retail 
Customers may be subject to with respect to any Telecommunications Service that
BA may, in its discretion and to the extent not prohibited by Applicable Lawss,
discontinue offering. Except as otherwise provided by this Agreement or
Applicable Lawss, BA will give MFS notice in writing or electronically (which
may be by giving MFS access to a database or an Internet site that contains the
applicable information, or by other electronic means) of material modification
of the operation, or discontinuance, of BA Retail Telecommunications Services
(as defined in Schedule 12.3) furnished under this Agreement for resale at least
60 days prior to the time the material modification or discontinuance becomes
effective.

          12.4.3 BA shall not be obligated to offer to MFS at a wholesale 
discount Telecommunications Services that BA offers at a special promotional 
rate if such promotions are for a limited duration of ninety (90) days or less.

          12.4.4 MFS shall provide to BA, in accordance with BA's Tariff's, 
adequate assurance of payment of charges due to BA in connection with MFS's 
purchase of BA Telecommunications Services for resale. For the purposes of 
providing such adequate assurance of payment, MFS shall be deemed to be a 
business customer, even if MFS is purchasing Telecommunications Services for 
resale to residential customers.

          12.4.5 MFS shall not be eligible to participate in any BA plan or 
program under which BA end user retail Customers may obtain products or 
merchandise, or services which are not Bell Atlantic Retail Telecommunications 
Services (as defined in Schedule 12.3), in return for trying, agreeing to 
purchase, purchasing, or using Bell Atlantic Retail Telecommunications Services.

                                      36

<PAGE>
 
13.0    COLLOCATION -- SECTION 251(c)(6).

        13.1   BA shall offer to MFS Physical Collocation of equipment necessary
for Interconnection (pursuant to Section 4) or for access to unbundled Network
Elements (pursuant to Section 11.0), except that BA may offer only Virtual
Collocation if BA demonstrates to the Commission that Physical Collocation is
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for
the purpose of Interconnection with facilities or services of BA or access to
unbundled Network Elements of BA, except as otherwise mutually agreed to in
writing by the Parties or as required by the FCC or the Commission, subject to
applicable federal and state Tariffs.


        13.2   Although not required to do so by Section 251(c)(6) of the Act,
by this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to 
Section 4) on a non-discriminatory basis and at comparable rates, terms and 
conditions as MFS may provide to other third parties. MFS shall provide such 
Collocation subject to applicable Tariffs.

        13.3   Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for Physical Collocation for MFS. MFS may elect to
(i) retain its Virtual Collocation in that premises, and/or (ii) establish
Physical Collocation in that premises pursuant to current procedures and
applicable Tariffs. BA will not assess to MFS non-recurring charges for central
office common area construction to transition existing virtual collocation
arrangements to physical collocation arrangements in offices where MFS
previously paid such charges. BA will also waive cage construction charges for
cages of the same size originally paid for by MFS. MFS shall coordinate with BA
for rearrangement of MFS's equipment, facilities, and circuits. All applicable
Physical Collocation recurring charges shall apply.

        13.4   Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for MFS as Virtual Collocation. MFS may elect to (i)
retain its Virtual Collocation in that premises, or (ii) unless it is not 
practical for technical reasons or because of space limitations, convert its 
Virtual Collocation at such premises to Physical Collocation, in which case MFS 
shall coordinate the construction and rearrangement with BA of its equipment, 
facilities, and circuits, and for which MFS shall pay BA at applicable Tariff 
rates. In addition, all Physical Collocation recurring charges shall apply.

        13.5   For both Physical Collocation and Virtual Collocation, the 
Collocating Party shall provide its own or third-party leased transport 
facilities and terminate those transport facilities in equipment located in its 
Physical Collocation space, or in its virtually collocated equipment, at the 
Housing Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

        13.6   Collocation shall occur under the terms of each Party's 
applicable and available Tariffs. Collocation is offered for network 
Interconnection between the Parties. Unless otherwise agreed to by the Parties 
or either Party is required by applicable law to permit on its collocated

                                      37
          
<PAGE>
 
premises, neither Party shall use a Collocation Arrangement to directly 
interconnect with a third party's equipment or facilities collocated at the same
location.


                           SECTION 251(B) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2).

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability
("LTNP") on a reciprocal basis to each other to the extent technically feasible,
and in accordance with rules and regulations as from time to time prescribed by
the FCC and or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the 
industry pursuant to regulations issued by the FCC and/or the Commission, the 
Parties agree to reciprocally provide Interim Number Portability to each other 
at the prices listed in Exhibit A. Such agreed-upon prices for INP are not 
intended to reflect either Party's views on the cost recovery mechanisms being 
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable 
FCC and/or Commission order(s) or regulations mandating the adoption of a 
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence 
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as 
practically possible while minimizing interruption or degradation of service to 
their respective Customers. Once PNP is implemented, either Party may withdraw, 
at any time and at its sole discretion, its INP offerings, subject to advance 
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant 
to FCC or Commission regulation, both Parties agree to conform and provide such 
PNP. To the extent PNP rates or cost recovery mechanisms are not established by 
the applicable FCC or Commission order or regulation mandating the adoption of 
PNP, the Parties will negotiate in good faith the charges or cost recovery 
mechanism for PNP service at such time as a PNP arrangement is adopted by the 
Parties.

          14.1.4  Under either an INP or PNP arrangement, MFS and BA will 
implement a process to coordinate LTNP cutovers with ULL conversions (as 
described in Section 11 of this Agreement).

     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1  A Customer of one Party ("Party A") elects to become a 
Customer of the other Party ("Party B"). The Customer elects to utilize the 
original telephone number(s)

                                      38

<PAGE>
 
corresponding to the Telephone Exchange Service(s) it previously received from 
Party A, in conjunction with the Telephone Exchange Service(s) it will now 
receive from Party B. Upon receipt of a service order from Party B requesting 
assignment of the number(s) to Party B. Party A will implement an arrangement 
whereby all calls to the original telephone number(s) will be forwarded to a new
telephone number(s) designated by Party B, only within the same Exchange Area as
the original telephone number(s). Party A will route the forwarded traffic to 
Party B over the appropriate traffic exchange trunk groups.

          14.2.2 Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties. Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3 Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated 
with those forwarded numbers as directed by Party B. In addition, Party A  will 
update the retained numbers in the LIDB with the screening options provided by 
Party B on a per order basis. Party B shall determine which of the screening 
options offered by Party A should apply to the Party B Customer account.

          14.2.4 Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as 
the appropriate address information of the Customer.

          14.2.5 Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a
third party that is authorized to act on behalf of the Customer. Party A shall
provide notification to Party B of third party orders affecting the INP service
of a Party B customer. The Parties agree to work cooperatively to develop
procedures or adopt industry standards or practices concerning the initiation
and termination of INP services in a multi-carrier environment.

          14.2.6 The INP service offered herein shall not initially apply to NXX
Codes 555, 915, 976, or 950, or for Feature Group A or coin telephone service. 
Upon request of either Party, provision of INP to these services will be 
mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any 
arrangement that would render the forwarded call Toll Traffic.

          14.2.7 The ordering of INP arrangements and the exchange of screening 
information shall be made in accordance with industry-accepted (e.g. OBF 
                                                                - - 
developed) format and specifications to the extent they have been implemented by
the Parties

                                      39
<PAGE>
 
     14.3 PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS 
(FLEX-DID)  Either Party may also request INP through Direct Inward Dial Trunks 
pursuant to any applicable Tariffs.

     14.4 PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION  Where 
either Party has activated an entire NXX for a single Customer, or activated a 
substantial portion of an NXX for a single Customer, with the remaining numbers 
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other 
Party, the first Party shall cooperate with the second Party to have the entire 
NXX reassigned in the LERG (and associated industry databases, routing tables, 
etc.) to an End Office operated by the second Party. Such transfer will be 
accomplished with appropriate coordination between the Parties and subject to 
appropriate industry lead-times for movements of NXXs from one switch to 
another. Neither Party shall charge the other in connection with this 
coordinated transfer.

     14.5 RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described 
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed 
numbers should be received by each Customer's chosen LEC as if each call to the 
Customer had been originally addressed by the caller to a telephone number 
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to 
accomplish this objective where INP is employed, the Parties shall utilize the 
process set forth in this subsection 14.5 whereby terminating compensation on 
calls subject to INP will be passed from the Party (the "Performing Party") 
which performs the INP to the other Party (the "Receiving Party") for whose 
Customer the INP is provided.

          14.5.1  The Parties shall individually and collectively make best 
efforts to track and quantify INP traffic between their networks based on the 
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving 
Party shall charge the Performing Party for each minute of INP traffic at the 
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other 
compensation charges for terminating such traffic, except as provided in 
subsection 14.5.2.

          14.5.2  By the Interconnection Activation Date in each LATA, the 
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal 
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra 
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as 
Transit Traffic. On the date which is six (6) months after the Interconnection 
Activation Date, and thereafter on each succeeding six month anniversary of such
Interconnection Activation Date, the Parties shall establish new INP traffic 
percentages to be applied in the prospective six (6) month period, based on the 
Performing Party's choice of actual INP traffic percentages from the preceding
six (6) month period or historic data of all traffic in the LATA.

          14.5.3  The INP Traffic Rate shall be equal to the sum of:

                                      40
<PAGE>
 
  (Recip Traffic percentage times the Reciprocal Compensation Rate set forth 
                            -----
in Exhibit A)
                                     plus
                                     ----

     (Intra Traffic percentage times Receiving Party's effective intrastate FGD
                               -----
rates)
                                     plus
                                     ----

     (Inter Traffic percentage times Receiving Party's effective interstate FGD
                               -----
rates).

     The Receiving Party shall compensate the Performing Party for its billing
and collection of charges for the intrastate and interstate FGD access services
provided by the Receiving Party to a third party through the greater of (i) the
difference between the intrastate and interstate FGD rates of the Receiving
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     1.46      RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this Section 14, in 
light of the FCC's First Report and Order and Further Notice of Proposed 
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the 
Parties stipulate and agree as follows:

               14.6.1    The rates listed in Exhibit A for the provision of INP 
are appropriate amounts that each Party providing INP service should recover for
the provision of those INP functionalities in BA's operating territory. For the 
INP functions it provides, each Party should be allowed to recover these amounts
in a manner consistent with any final FCC and/or Commission order on INP cost 
recovery (such as a state-wide fund contributed to by all telecommunications 
carriers).

               14.6.2    Within three (3) weeks of the Effective Date, the 
Parties will jointly seek a Commission proceeding and ruling to develop and 
implement an INP cost recovery mechanism consistent with the policy described 
in the Order and/or any subsequent FCC or Commission decision.

               14.6.3    Until such time as a final FCC and or Commission order,
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the other Party at the INP rates listed in Exhibit A. All revenues
received by the providing Party from its provision of INP service to the other
Party shall be placed into an escrow fund maintained by or tracked separately by
the providing Party. Upon issuance of a final FCC and/or Commission order, and
to the extent that it permits the Party providing INP to recover the associated
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal to the amount it recovers from such fund for its provision
of INP service to the purchasing Party from the Effective Date, provided that in
no event shall the refund amount exceed the aggregate amount the providing Party
has received from the purchasing Party's INP services. If no such

                                      41
<PAGE>
 
fund is ordered or established, the providing Party shall retain the full amount
of the revenues tracked or held in escrow by it pursuant to this subsection 
14.6.3.

          14.6.4  The Parties agree that neither Party waives its rights to 
advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.

15.0      DIALING PARITY -- SECTION 251(B)(3)


          BA and MFS shall each provide the other with nondiscriminatory access 
to such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.

16.0      ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4)


          Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C. 
(S) 224, as set forth in Exhibit A, where facilities are available, on terms, 
conditions and prices comparable to those offered to any other entity pursuant 
to each Party's applicable Tariffs. Where no such Tariffs exist, such access 
shall be provided in accordance with the requirements of 47 U.S.C. (S) 224, 
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C. (S) 224 
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the 
appropriateness of applying such changes on a retroactive basis to the date 
hereof. If the Parties are unable to agree on the necessary changes to the 
existing arrangements or the appropriateness of applying them on a retroactive 
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.


17.0      DATABASES AND SIGNALING.

          17.1    Each Party shall provide the other Party with access to 
databases and associated signaling necessary for call routing and completion by 
providing SS7 Common Channel Signaling (CCS) Interconnection in accordance with 
existing Tariffs, and Interconnection and access to 800/888 databases. LIDB, and
any other necessary databases in accordance with existing Tariffs and/or
agreements with other unaffiliated carriers, as set forth in the Exhibit A. 
Alternatively, either Party may secure CCS Interconnection from a commercial 
SS7 hub provider, and in that case the other Party will permit the purchasing 
Party to access the same databases as would have been accessible if the 
purchasing party had connected directly to the other Party's CCS network.

                                      42
<PAGE>
 
     17.2      The Parties will provide CCS Signaling to one another, where and 
as available, in conjunction with all Local Traffic, Toll Traffic, Meet Point 
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between 
their respective networks, including all CLASS features and functions, to the 
extent each Party offers such features and functions to its Customers. All CCS 
Signaling parameters will be provided upon request (where available), including 
called party number, calling party number, originating line information, 
calling party category, and charge number. All privacy indicators will be 
honored. The Parties will follow all Ordering and Billing Forum-adopted 
standards pertaining to CIC/OZZ codes. Where CCS Signaling is not available, 
in-band multi-frequency (MF) wink start signaling will be provided. Any such MF 
arrangement will require a separate local trunk circuit between the Parties' 
respective switches. In such an arrangement, each Party will outpulse the full 
ten-digit telephone number of the called party to the other Party.

     17.3      Each Party shall provide trunk groups, where available and upon
reasonable request, that are configured utilizing the B8ZS & ESF protocol for 64
kbps clear channel transmission to allow for ISDN interoperability between the
Parties' respective networks.

     17.4      The following publications describe the practices, procedures and
specifications generally utilized by BA for signaling purposes and is listed
herein to assist the Parties in meeting their respective Interconnection
responsibilities related to Signaling:

               (a)  Bellcore Special Report SR-TSV-002275. BOC Notes on the LEC 
Networks - Signaling; and
               
               (b)  Bell Atlantic Supplement Common Channel Signaling Network 
Interface Specification (BA-905).

     17.5      Each Party shall charge the other Party mutual and reciprocal 
rates for CCS Signaling as follows: BA shall charge MFS in accordance with 
Exhibit A hereto and applicable Tariffs; MFS shall charge BA rates equal to the
rates BA charges MFS, unless MFS's Tariffs for CCS signaling provide for lower 
generally available rates, in which case MFS shall charge BA such lower rates.


18.0 COORDINATED SERVICE ARRANGEMENTS.

     18.1      INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its
service provider from BA to MFS, or from MFS to BA, and does not retain its
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides details on the Customer's new number or provide
other appropriate information to the extent known. Referral Announcements shall
be provided reciprocally, free of charge to either the other Party or the
Customer to the extent the providing Party does not charge its own customers for

                                      43
<PAGE>
 
such service, for a period of not less than four (4) months after the date the 
Customer changes its telephone number in the case of business Customers and not 
less than sixty (60) days after the date the Customer changes its telephone 
number in the case of residential Customers. However, if either Party provides 
Referral Announcements for different periods than the above respective periods 
when its Customers change their telephone numbers, such Party shall provide the 
same level of service to Customers of the other Party.

      18.2 COORDINATED REPAIR CALLS. MFS and BA will employ the following 
procedures for handling misdirected repair calls:

           18.2.1 MFS and BA will educate their respective Customers as to the 
correct telephone numbers to call in order to access their respective repair 
bureaus.

           18.2.2 To the extent Party A is identifiable as the correct provider
of service to Customers that make misdirected repair calls to Party B, Party B
will immediately refer the Customers to the telephone number provided by Party
A, or to an information source that can provide the telephone number of Party A,
in a courteous manner and at no charge. In responding to misdirected repair
calls, neither Party shall make disparaging remarks about the other Party, its
services, rates, or service quality.
           
           18.2.3 MFS and BA will provide their respective repair contact
numbers to one another on a reciprocal basis. 

      18.3 CUSTOMER AUTHORIZATION. In order for either Party to order or
terminate service on behalf of the other Party's Customer, the requesting Party
must have proper written authorization from the customer in its files, and
provide a copy of such authorization to the other Party upon request. In the
event the requesting Party (i) fails to provide a copy of the Customer's proper
written authorization upon request, (ii) requests changes in the other Party's
Customer's service without having such authorization in it files, or (iii)
mistakenly changes the other Party's Customer's service, the requesting Party
shall be liable to the other Party for all charges that would be applicable to
the Customer for restoring service to the other Party.
19.0  DIRECTORY SERVICES ARRANGEMENTS 

      BA will, upon request, provide the following directory services to MFS in
accordance with the terms set forth herein. In this Section 19, references to a
MFS Customer's "primary listing" shall mean such Customer's name, address, and
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP 
arrangements with BA or any other carrier within the geographic area covered in 
the relevant BA directory.


      19.1 DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS



                                      44




           
<PAGE>
 
          19.1.1  BA will include the MFS Customer's primary listing in its
"White Pages" directory (residence and business listings) and "Yellow Pages"
directory (business listings) that cover the address of the Customer. Listings
of MFS's Customers will be interfiled with listings of BA's Customers and the
Customers of other LECs included in the BA directories. MFS will pay BA a non-
recurring charge as set forth in Exhibit A for providing such service for each
MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as the
case may be, for additional and foreign white page listings and other white
pages services for MFS's Customers. BA will not require a minimum number of
listings per order.

          19.1.2  BA will also include the MFS Customer's primary listing in
BA's directory assistance database on the same basis that BA's own Customers are
included, as well as in any electronic directories in which BA's Customers are
ordinarily included, for no charge other than the charges identified in
subsection 19.1.1.

          19.1.3  BA will distribute to MFS Customers copies of their primary
white pages and yellow pages directories at the same time and on the same basis
that BA distributes primary directories to its own Customers. BA will also
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional
directories from BA's Directory Fulfillment Centers, which Centers will provide
such additional directories for the same charges applicable to comparable
requests by BA Customers.

          19.1.4  BA will include all MFS NXX codes associated with the areas to
which each directory pertains, along with BA's own NXX codes in any maps or
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same
manner as BA's NXX information.

          19.1.5  MFS shall provide BA with daily listing information on all new
MFS Customers in the format required by BA or a mutually-agreed upon industry
standard format. The information shall include the Customer's name, address,
telephone number, the delivery address and number of directories to be
delivered, and, in the case of a business listing, the primary business heading
under which the business Customer desires to be placed, and any other
information necessary for the publication and delivery of directories. MFS will
also provide BA with daily listing information showing Customers that have
disconnected or terminated their service with MFS. BA will provide MFS with
confirmation of listing order activity within forty eight (48) hours.

          19.1.6  BA will accord MFS's directory listing information the same
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be
used solely for the purpose of providing directory services, provided, however,
that BA may use or license information contained in its directory listings for
direct marketing purposes so long as the MFS Customers are not separately
identified as such, and provided further that MFS may identify those of its
Customers that request that their names not be sold for direct marketing
purposes, and will honor such requests to the same extent as it does for its own
Customers. 

                                      45
<PAGE>
 
           19.1.7  BA or BA's publisher shall provide MFS with a report of all
MFS Customer listings ninety (90) days prior to directory publication in such
form and format as may be mutually agreed to by both Parties. Both Parties
shall use their best efforts to ensure the accurate listing of such information.
BA will also provide MFS, upon request, a copy of the BA listings standards
and specifications manual. In addition, BA will provide MFS with a listing of
Yellow Pages headings and directory close schedules on an ongoing basis.

           19.1.8  MFS will adhere to all practices, standards, and ethical
requirements of BA with regard to listings, and, by providing BA with listing
information, warrants to BA that MFS has the right to place such listings on
behalf of its Customers. MFS agrees that it will undertake commercially
practicable and reasonable steps to attempt to ensure that any business or
person to be listed is authorized and has the right (i) to provide the product
or service offered, and (ii) to use any personal or corporate name, trade name
or language used in the listing.

           19.1.9  BA's liability to MFS in the event of a BA error in or
omission of a listing shall be subject to the same limitations that BA's
liability to its own Customers are subject to. In addition, MFS agrees to
take, with respect to its own Customers, all reasonable steps to ensure that its
and BA's liability to MFS's Customers in the event of a BA error in or omission
of a listing shall be subject to the same limitations that BA's liability to its
own Customers are subject to.

     19.2  YELLOW PAGE MAINTENANCE. The Parties agree to work cooperatively
to ensure that Yellow Page advertisements purchased by Customers that switch
their service to MFS (including Customers utilizing MFS-assigned telephone
numbers and MFS Customers utilizing LTNP) are maintained without interruption.
BA will allow MFS Customers to purchase new Yellow Pages advertisements without
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. BA and MFS may implement a commission program whereby MFS may, at
MFS's sole discretion, act as a sales, billing and collection agent for Yellow
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

     19.3  SERVICE INFORMATION PAGES. BA will include in the "Customer Guide" or
comparable section of the applicable white pages directories listings provided
by MFS for MFS's installation, repair and customer service and other essential
service oriented information, as agreed by the Parties, including appropriate
identifying logo. Such listings shall appear in the manner agreed to by the
Parties. BA shall not charge MFS for inclusion of this essential service-
oriented information, but reserves the right to impose charges on other
information MFS may elect to submit and BA may elect to accept for inclusion in
BA's white pages directories. BA will provide MFS with the annual directory
close dates and reasonable notice of any changes in said dates.

     19.4  DIRECTORY ASSISTANCE (DA); CALL COMPLETION

           19.4.1  Upon request, BA will provide MFS with directory assistance
and/or call completion services substantially in accordance with the terms set
forth in the form Directory Assistance and Call Completion Services Agreement
appended hereto as Exhibit C.

                                      46
<PAGE>
 
 
               19.4.2    Also upon request, BA will provide to MFS operator
services trunk groups, utilizing Feature Group D type signaling, with ANL minus
OZZ when interconnecting to the BA operator services network.

20.0   COORDINATION WITH TARIFF TERMS

       20.1    The Parties acknowledge that some of the services, facilities, 
and arrangements described herein are or will be available under and subject to 
the terms of the federal or state tariffs of the other Party applicable to such
services, facilities, and arrangements. To the extent a Tariff of the providing
Party applies to any service, facility, and arrangement described herein, the
Parties agree as follows:

               20.1.1    Those rates and charges set forth in Exhibit A for the
services, facilities, and arrangements described herein that are designated with
an asterisk shall remain fixed for the initial term of the Agreement,
notwithstanding that such rates may be different from those contained in an
effective, pending, or future Tariff of the providing Party (including any
changes to such Tariff subsequent to the Effective Date). Those rates and
charges for services, facilities, and arrangements that are not designated with
an asterisk, and reference or are identical to a rate contained in an existing
Tariff of the providing Party, shall conform with those contained in the then-
prevailing Tariff and vary in accordance with any changes that may be made to
the Tariff rates and charges subsequent to the Effective Date. Even the
asterisked fixed rates and charges shall be changed to reflect any changes in
the Tariff rates and charges they reference, however, if the Parties agree to
adopt the changed Tariff rates and charges.

       20.2    Except with respect to the rates and charges described in 
subsection 20.1 above, all other terms contained in an applicable Tariff of the 
providing Party shall apply in connection with its provision of the particular
service, facility, and arrangement hereunder.

21.0   INSURANCE

       21.1    MFS shall maintain, during the term of this Agreement, all 
insurance and/or bonds required by law and necessary to satisfy its obligations 
under this Agreement, including without limitation, its obligations set forth in
Section 25 hereof. At a minimum and without limiting the foregoing covenant, 
MFS shall maintain the following insurance:

               (a)  Commercial General Liability Insurance, on an occurrence
       basis, including but not limited to, premises-operations, broad form
       property damage, products/completed operations, contractual liability,
       independent contractors, and personal injury, with limits of at least
       $1,000,000 combined single limit for each occurrence.

               (b)  Automobile Liability, Comprehensive Form, with limits of at 
       least $500,000 combined single limit for each occurrence.

                                      47


<PAGE>
 
            (c)  Excess Liability, in the umbrella form, with limits of at least
      $15,000,000 combined single limit for each occurrence.

            (d)  Worker's Compensation Insurance as required by law and
      Employer's Liability Insurance with limits of not less than $1,000,000 per
      occurrence.


      21.2   MFS shall name BA as an additional insured on the foregoing
insurance. MFS agrees that MFS's insurer(s) and anyone claiming by, through,
under or on behalf of MFS, shall have no claim, right of action, or right of
subrogation, against BA. BA's affiliated companies, or the directors, officers
or employees of BA or BA's affiliated companies, based on any loss or liability
insurable under the foregoing insurance.

      21.3   MFS shall, within two (2) weeks of the date hereof and on a 
quarterly basis thereafter, furnish certificates or other adequate proof of the 
foregoing insurance. The certificates or other proof of the foregoing insurance 
shall be sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court 
House Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall 
require its agents, representatives, or contractors, if any, that may enter upon
the premises of BA or BA's affiliated companies to maintain similar and 
appropriate insurance and, if requested, to furnish BA certificates or other 
adequate proof of such insurance. Certificates furnished by MFS or MFS's agents,
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to 
cancellation of, or any material change in, the insurance."

22.0  TERM AND TERMINATION.

      22.1   This Agreement shall be effective as of the date first above
written and continue in effect until July 1, 1999, and thereafter the Agreement
shall continue in force and effect unless and until terminated as provided
herein. Upon the expiration of the initial term, either Party may terminate this
Agreement by providing written notice of termination to the other Party, such
written notice to be provided at least ninety (90) days in advance of the date
of termination. In the event of such termination, those service arrangements
made available under this Agreement and existing at the time of termination
shall continue without interruption under (a) a new agreement executed by the
Parties, (b) standard Interconnection terms and conditions approved and made
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of
this Agreement on a month-to-month basis until such time as (a), (b), or (c)
becomes available.

     22.2    For service arrangements made available under this Agreement and 
existing at the time of termination, if the standard Interconnection terms and 
conditions of Tariff terms and conditions result in the non-terminating Party 
physically rearranging facilities or incurring programming expense, the 
non-terminating Party shall be entitled to recover such rearrangement or 
programming costs, from the terminating Party. By mutual agreement, the Parties
may jointly petition the appropriate regulatory bodies for permission to have
this Agreement supersede any future standardized agreements or rules as such
regulators might adopt or approve

                                      48
<PAGE>
 
     22.3  If either Party defaults in the payment of any amount due hereunder, 
or if either Party violates any other provision of this Agreement, and such 
default or violation shall continue for sixty (60) days after written notice 
thereof, the other Party may terminate this Agreement and services hereunder by 
written notice; provided the other Party has provided the defaulting Party and 
the appropriate federal and/or state regulatory bodies with written notice at 
least twenty five (25) days' prior to terminating service. Notice shall be 
posted by certified mail, return receipt requested. If the defaulting Party 
cures the default or violation within the twenty five (25) day period, the other
Party will not terminate service or this Agreement but shall be entitled to 
recover all costs, if any, incurred by it in connection with the default or 
violation, including, without limitation, costs incurred to prepare for the 
termination of service.


23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.
     
     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES ANY 
WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND 
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE PARTIES 
DISCLAIM THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A
PARTICULAR PURPOSE.


24.0 CANCELLATION CHARGES.
     
     Except as provided in this Agreement or as otherwise provided in any 
applicable Tariff, no cancellation charges shall apply.


25.0 INDEMNIFICATION.

     25.1  Each Party agrees to release, indemnify, defend and hold harmless the
other Party from and against all losses, claims, demands, expenses, suits or
other actions, or any liability whatsoever, including, but not limited to, costs
and attorneys' fees (collectively, a "Loss"), (a) whether suffered, made,
instituted, or asserted by any other party or person, (i) relating to personal
injury to or death of any person, or for loss, damage to, or destruction of real
and/or personal property, whether or not owned by others, incurred during the
term of this Agreement and to the extent proximately caused by the acts or
omissions of the indemnifying Party, regardless of the form of action, or (ii)
arising out of BA's listing of the directory listing information provided by MFS
pursuant to subsection 19.1. or (b) suffered, made, instituted, or asserted by
its own customer(s) against the other Party arising out of the other Party's
provision of services to the indemnifying Party under this Agreement.
Notwithstanding the foregoing indemnification, nothing in this such Section 25,
shall affect or limit any claims, remedies, or other actions the indemnifying
Party may have against the indemnified Party under this Agreement, any other
contract, or any applicable Tariff(s), regulations or laws for the indemnified
Party's provision of said services.

                                      49

<PAGE>
 
     25.2 The indemnification provided herein shall be conditioned upon:

          (a) The indemnified Party shall promptly notify the indemnifying Party
     of any action taken against the indemnified Party relating to the
     indemnification.

          (b) The indemnifying Party shall have sole authority to defend any
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c) In no event shall the indemnifying Party settle or consent to any
     judgment pertaining to any such action without the prior written consent of
     the indemnified Party, which consent shall not be unreasonably withheld.

          (d) The indemnified Party shall, in all cases. assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e) The indemnified Party shall offer the indemnifying Party all
     reasonable cooperation and assistance in the defense of any such action.

     25.3 In addition to its indemnity obligations under subsection 25.1, each
Party shall provide, in its tariffs and contracts with its Customers that relate
to any Telecommunications Service or Network Element provided or contemplated
under this Agreement, that in no case shall such Party or any of its agents,
contractors or others retained by such parties be liable to any Customer or
third party for (i) any Loss relating to or arising out of this Agreement,
whether in contract or tort, that exceeds the amount such Party would have
charged the applicable Customer for the service(s) or function(s) that gave rise
to such Loss, and (ii) any Consequential Damages (as defined in subsection 26.2
below).


26.0 LIMITATION OF LIABILITY.

     26.1 Except as may be provided pursuant to Section 27 below, the liability
of either Party to the other Party for damages arising out of failure to comply
with a direction to install, restore or terminate facilities; or out of
failures, mistakes, omissions, interruptions, delays, errors, or defects
occurring in the course of furnishing any services, arrangements, or facilities
hereunder shall be determined in accordance with the terms of the applicable
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro rata monthly
charge for the period in which such failures, mistakes, omissions,
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for
such failures, mistakes, omissions, interruptions, delays, errors or defects.

     26.2 Neither Party shall be liable to the other in connection with the
provision or use of services offered under this Agreement for indirect,
incidental, consequential, reliance or special

                                      50
<PAGE>
 
damages, including (without limitation) damages for lost profits (collectively,
"Consequential Damages"), regardless of the form of action, whether in contract
warranty, strict liability, or tort, including, without limitation, negligence
of any kind, even if the other Party has been advised of the possibility of such
damages; provided, that the foregoing shall not limit a Party's obligation under
Section 25.

     26.3 The Parties agree that neither Party shall be liable to the customers
of the other Party in connection with its provision of services to the other
Party under this Agreement. Nothing in this Agreement shall be deemed to create
a third party beneficiary relationship between the Party providing the service
and the customers of the Party purchasing the service. In the event of a dispute
involving both Parties with a customer of one Party, both Parties shall assert
the applicability of any limitations on liability to customers that may he
contained in either Party's applicable Tariff(s).


27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

     27.1 CERTAIN DEFINITIONS. When used in this Section 27, the following
terms shall have the meanings indicated:

          27.1.1  "Specified Performance Breach" means the failure by BA to meet
the Performance Criteria for any one of the three Specified Activities for a
period of three (3) consecutive calendar months.

          27.1.2  "Specified Activity" means any of the following activities:

          (a)  the installation by BA of Unbundled Local Loop Elements for MFS
     ("ULL Installation");

          (b)  BA's provision of INP to MFS or

          (c)  repair of out of service problems for MFS ("Out of Service
               Repairs").

          27.1.3  "Performance Criteria" means, with respect to any calendar
month during the term of this Agreement, the performance by BA during such month
of each Specified Activity (except Out-of-Service Repairs) shown in Schedule
27.0, within the time interval shown, in at least eighty percent (80%) of the
covered instances. BA shall perform the Out-of-Service Repairs within the
specified time interval in at least seventy percent (70%) of the covered
instances. Within one week of each anniversary of the Effective Date, the 
Parties shall jointly review BA's actual network-wide monthly performance
percentages for Out-of-Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual
percentages for any three consecutive month period and/or the full preceding
year, up to and including an eighty percent (80%) standard, as the Out-of-
Service Repairs percentage standard applicable to the following year.

                                      51
<PAGE>
 
     27.2 PERFORMANCE STANDARDS. BA shall exercise best efforts to meet the
Performance Criteria for the three Specified Activities. In the event BA fails
to meet the Performance Criteria at any time during the term of this Agreement.
MFS shall be entitled to pursue all remedies set forth in the applicable BA
Tariffs, except as may be agreed to by the Parties. In addition, if BA commits a
Specified Performance Breach during the term of this Agreement, the Parties
agree to meet immediately to determine whether any liquidated damages provisions
are appropriate as an amendment hereof in light of such Breach and, if so, the
terms therein; provided, however, that if BA commits a Specified Performance
Breach during initial nine (9) months of this Agreement, the Parties agree to
meet at the end of the nine-month period. If the Parties are unable to agree as
to the appropriateness of the liquidated damages provisions and or the terms
therein within ninety (90) days after the date of the first meeting pursuant to
this subsection, or if no such meeting has occurred within ninety (90) days of
the end of the nine-month period for reasons other than the mutual agreement of
the Parties, the Parties agree to submit to arbitration such disagreement and
request that the arbitrators base their decision on comparable ILEC-CLEC
interconnection agreements. Unless otherwise agreed to by the Parties, the
arbitration shall be conducted by a panel of three (3) arbitrators, one to be
appointed by each Party pursuant to CPR's Non-Administered Arbitration Rules and
subject to the United States Arbitration Act (9 U.S.C. (S)(S) 1-16), to be
conducted in Arlington, Virginia. The Parties agree that the liquidated damages
provisions, if any, finally determined by the arbitral process shall be adopted
as an amendment to this Agreement.

     27.3 LIMITATIONS. In no event shall BA be deemed to have failed to meet
any of the Performance Criteria if:

          27.3.1  BA's failure to meet or exceed any of the Performance Criteria
is caused, directly or indirectly, by a Delaying Event. A "Delaying Event" means
(a) a failure by MFS to perform any of its obligations set forth in this
Agreement (including, without limitation, the Implementation Schedule and the
Joint Grooming Plan), (b) any delay, act or failure to act by a Customer, agent,
representative, or subcontractor of MFS or (c) any Force Majeure Event. If a
Delaying Event prevents or delays BA from performing a Specified Activity, then
such Specified Activity shall be excluded from the calculation of BA's
compliance with the Performance Criteria, provided BA performs the Specified
Activity in the course of its normal service cycle once the Delaying Event no
longer exists: or

          27.3.2  the Parties agree to a time interval with respect to a
particular order that exceeds the interval set forth in Schedule 27. In such
event, the time interval for BA's performance of the Specified Activit(ies) set
forth in the order shall be extended to such later date agreed to by the
Parties.

     27.4 SERVICE QUALITY STANDARDS. MFS agrees to specific performance
standards associated with quality of service requests as specified in Schedule
27.1. Should MFS fail to meet these service quality standards, during a period
in which BA has failed to meet the Performance Criteria. BA's failure during
such time period shall be excused and not apply toward the calculation of a
Specified Performance Breach.

                                      52
<PAGE>
 
     27.5  RECORDS. Each Party shall maintain complete and accurate records in
the manner and format agreed to by the Parties, on a monthly basis, of BA's
performance under this Agreement of each Specified Activity and its compliance
with the Performance Criteria during the initial nine-month period. Each Party
shall provide to the other Party such records in a self-reporting format on a
monthly basis. The Parties agree that such records shall be deemed "Proprietary
Information" for purposes of subsection 29.4.


28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

     28.1  Each Party represents and warrants that it is now and will remain
in compliance with all laws, regulations, and orders applicable to the
performance of its obligations hereunder (collectively, "Applicable Laws"). Each
Party shall promptly notify the other Party in writing of any governmental 
action that suspends, cancels, withdraws, limits, or otherwise materially
affects its ability to perform its obligations hereunder.

     28.2  The Parties understand and agree that this Agreement will be filed
with the Commission and may thereafter be filed with the FCC. The Parties
covenant and agree that this Agreement is satisfactory to them as an agreement
under Section 251 of the Act. Each Party covenants and agrees to fully support
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties however, reserve the right to seek
regulatory relief and otherwise seek redress from each other regarding
performance and implementation of this Agreement.

     28.3  The Parties recognize that the FCC is currently promulgating
regulations implementing the Act, including, without limitation, Sections 251,
252 and 271 thereof (the "FCC Regulations"), that may affect the terms
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties
agree to make only the minimum revisions necessary to eliminate the
inconsistency. Such minimum changes to conform this Agreement to the FCC
Regulations shall not be considered material, and shall not require further
Commission approval (beyond any Commission approval required under Section
252(e) of the Act).

     28.4  In the event any Applicable Laws other than the FCC Regulations
requires modification of any material term(s) contained in this Agreement,
either Party may require a renegotiation of the term(s) that require direct
modification as well as of any term(s) that are reasonably affected thereby. If
neither Party requests a renegotiation or if an Applicable Laws requires
modification of any non-material term(s), then the Parties agree to make only
the minimum modifications necessary, and the remaining provisions of this
Agreement shall remain in full force and effect. For purposes of this subsection
28.4 and without limitation of any other modifications required by Applicable
Laws, the Parties agree that any modification required by Applicable Laws (i)
to the two-tier Reciprocal Call Termination compensation structure for the
transport and termination of Local Traffic described in Exhibit A, or (ii) that
affects either Party's receipt of reciprocal compensation for the transport and
termination of Local Traffic, shall be deemed to be a modification of a material
term that requires immediate good faith renegotiation between the Parties.

                                      53
<PAGE>
 
Until such renegotiation results in a new agreement or an amendment to this
Agreement between the Parties, the Parties agree that (y) in the case of (i)
above, they will pay each other appropriate transport charges in addition to
the usual call termination charge for Local Traffic that it delivers to the
other Party's Local Serving Wire Center, provided each Party continues to
offer the option of delivering Local Traffic to another IP in the LATA at the
usual call termination charge only, and (z) in the case of (ii) above, the Party
whose receipt of reciprocal compensation is affected shall not be obligated to
pay the other Party reciprocal compensation for the other Party's transport and
termination of the same kind of Local Traffic delivered by the affected Party in
excess of what the affected Party is permitted to receive and retain.


29.0   MISCELLANEOUS.

       29.1  AUTHORIZATION.

             29.1.1  BA is a corporation duly organized, validly existing and in
good standing under the laws of the Commonwealth of Virginia and has full
power and authority to execute and deliver this Agreement and to perform the
obligations hereunder on behalf of BA.

             29.1.2  MFS is a corporation duly organized, validly existing and
in good standing under the laws of the State of Delaware and has full power and
authority to execute and deliver this Agreement and to perform its obligations
hereunder.

       29.2  INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder
as an independent contractor and nothing herein shall be construed as creating
any other relationship between the Parties. Each Party and each Party's
contractor shall be solely responsible for the withholding or payment of all
applicable federal, state and local income taxes, social security taxes and
other payroll taxes with respect to their employees, as well as any taxes,
contributions or other obligations imposed by applicable state unemployment or
workers' compensation acts. Each Party has sole authority and responsibility to
hire, fire and otherwise control its employees.

       29.3  FORCE MAJEURE. Neither Party shall be responsible for delays or
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in
performance were foreseen or foreseeable as of the date of this Agreement,
including, without limitation: adverse weather conditions, fire, explosion,
power failure, acts of God, war, revolution, civil commotion, or acts of public
enemies: any law, order, regulation, ordinance or requirement of any government
or legal body: or labor unrest, including, without limitation, strikes,
slowdowns, picketing or boycotts: or delays caused by the other Party or by
other service or equipment vendors: or any other circumstances beyond the
Party's reasonable control. In such event, the affected Party shall, upon giving
prompt notice to the other Party, be excused from such performance on a day-to-
day basis to the extent of such interferences (and the other Party shall
likewise be excused from performance of its obligations on a day-for-day basis
to the extent such Party's obligations relate the performance so interfered
with). The affected Party shall use its best efforts to avoid or remove the 
cause(s) of non-

                                      54
<PAGE>
 
performance and both Parties shall proceed to perform with dispatch once the
cause(s) are removed or cease.

     29.4 CONFIDENTIALITY

          29.4.1  All information, including but not limited to specification,
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches,
models, samples, tools, technical information, data, employee records, maps,
financial reports, and market data, (i) furnished by one Party to the other
Party dealing with customer specific, facility specific, or usage specific
information, other than customer information communicated for the purpose of
publication or directory database inclusion, or (ii) in written, graphic,
electromagnetic, or other tangible form and marked at the time of delivery as
"Confidential" or "Proprietary", or (iii) communicated orally and declared to
the receiving Party at the time of delivery, or by written notice given to the
receiving Party within ten (10) days after delivery, to be "Confidential" or
"Proprietary" (collectively referred to as "Proprietary Information"), shall
remain the property of the disclosing Party.

          29.4.2  Each Party shall keep all of the other Party's Proprietary
Information confidential and shall use the other Party's Proprietary Information
only for performing the covenants contained in this Agreement. Neither Party
shall use the other Party's Proprietary Information for any other purpose
except upon such terms and conditions as may be agreed upon between the Parties
in writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality
and non-use set forth in this Agreement do not apply to such Proprietary
Information that:

          (a)  was, at the time of receipt, already known to the receiving Party
     free of any obligation to keep it confidential as evidenced by written
     records prepared prior to delivery by the disclosing Party; or

          (b)  is or becomes publicly known through no wrongful act of the
     receiving Party; or

          (c)  is rightfully received from a third person having no direct or
     indirect secrecy or confidentiality obligation to the disclosing Party with
     respect to such information; or

          (d)  is independently developed by an employee, agent, or contractor
     of the receiving Party that is not involved in any manner with the
     provision of services pursuant to this Agreement and does not have any
     direct or indirect access to the Proprietary Information; or

          (e)  is approved for release by written authorization of the
     disclosing Party; or

          (f)  is required to be made public by the receiving Party pursuant to
     applicable law or regulation, provided that the receiving Party shall give
     sufficient notice of the requirement to the disclosing Party to enable the
     disclosing Party to seek protective orders.

                                      55
<PAGE>
 
          29.4.4  Upon request by the disclosing Party, the receiving Party
shall return all tangible copies of Proprietary Information, whether written
graphic or otherwise, except that the receiving Party may retain one copy for
archival purposes only.

          29.4.5  Notwithstanding any other provision of this Agreement, the
provisions of this subsection 29.4 shall apply to all Proprietary Information
furnished by either Party to the other in furtherance of the purpose of this
Agreement, even if furnished before the Effective Date.

     29.5 CHOICE OF LAW. The construction, interpretation and performance of
this Agreement shall be governed by and construed in accordance with the laws of
the state in which this Agreement is to be performed, except for its conflicts
of laws provisions. In addition, insofar as and to the extent federal law may
apply, federal law will control.

     29.6 TAXES

          29.6.1.  In General. With respect to any purchase hereunder of
                   ----------                                           
services, facilities or arrangements, if any federal, state or local tax, fee,
surcharge or other tax-like charge (a "Tax") is required or permitted by
Applicable Laws (as defined in subsection 28.1) to be collected from the
purchasing Party by the providing Party, then (i) the providing Party shall
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

          29.6.2.  Taxes Imposed on the Providing Party. With respect to any
                   ------------------------------------                     
purchase hereunder of services, facilities or arrangements, if any federal,
state or local Tax is imposed by Applicable Laws on the receipts of the
providing Party, which Law permits the providing Party to exclude certain
receipts received from sales for resale to a public utility, distributor,
telephone company, local exchange carrier, telecommunications company or other
communications company ("Telecommunications Company"), such exclusion being
based solely on the fact that the purchasing Party is also subject to a tax
based upon receipts ("Receipts Tax"), then the purchasing Party (i) shall
provide the providing Party with notice in writing in accordance with subsection
29.6.6 of this Agreement of its intent to pay the Receipts Tax and (ii) shall
timely pay the Receipts Tax to the applicable tax authority.

          29.6.3.  Taxes Imposed on Customers. With respect to any purchase
                   --------------------------                              
hereunder of services, facilities or arrangements that are resold to a third
party, if any federal, state or local Tax is imposed by Applicable Laws on the
subscriber, end-user. Customer or ultimate consumer ("Subscriber") in connection
with any such purchase, which a Telecommunications Company is required to impose
and/or collect from a Subscriber, then the purchasing Party (i) shall be
required to impose and/or collect such Tax from the Subscriber and (ii) shall
timely remit such Tax to the applicable taxing authority.

          29.64.  Liability for Uncollected Tax, Interest and Penalty. If the
                  ---------------------------------------------------        
providing Party has not received an exemption certificate and fails to collect 
any Tax as required by subsection

                                      56
<PAGE>
 
29.6.1, then, as between the providing Party and the purchasing Party, (i) the
purchasing Party shall remain liable for such uncollected Tax and (ii) the
providing Party shall be liable for any interest assessed thereon and any
penalty assessed with respect to such uncollected Tax by such authority. If the
providing Party properly bills the purchasing Party for any Tax but the
purchasing Party fails to remit such Tax to the providing Party as required by
subsection 29.6.1, then, as between the providing Party and the purchasing
Party, the purchasing Party shall be liable for such uncollected Tax and any
interest assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. If the providing Party does
not collect any Tax as required by subsection 29.6.1 because the purchasing
Party has provided such providing Party with an exemption certificate that is
later found to be inadequate by a taxing authority, then, as between the
providing Party and the purchasing Party, the purchasing Party shall be liable
for such uncollected Tax and any interest assessed thereon, as well as any
penalty assessed with respect to such uncollected Tax by the applicable taxing
authority. If the purchasing Party fails to pay the Receipts Tax as required by
subsection 29.6.2, then, as between the providing Party and the purchasing
Party, (x) the providing Party shall be liable for any Tax imposed on its
receipts and (y) the purchasing Party shall be liable for any interest assessed
thereon and any penalty assessed upon the providing Party with respect to such
Tax by such authority. If the purchasing Party fails to impose and or collect
any Tax from Subscribers as required by subsection 29.6.3, then, as between the
providing Party the purchasing Party shall remain liable for such uncollected
Tax and any interest assessed thereon, as well as any penalty assessed with
respect to such uncollected Tax by the applicable taxing authority. With respect
to any Tax that the purchasing Party has agreed to pay, or is required to impose
on and/or collect from Subscribers, the purchasing Party agrees to indemnify and
hold the providing Party harmless on an after-tax basis for any costs incurred
by the providing Party as a result of actions taken by the applicable taxing
authority to recover the Tax from the providing Party due to the failure of the
purchasing Party to timely pay, or collect and timely remit, such Tax to such
authority. In the event either Party is audited by a taxing authority, the other
Party agrees to cooperate fully with the Party being audited in order to respond
to any audit inquiries in a proper and timely manner so that the audit and/or
any resulting controversy may be resolved expeditiously.

     29.6.5.   Tax Exemptions and Exemption Certificates. If Applicable Laws 
               -----------------------------------------
clearly exempts a purchase hereunder from a Tax, and if such Law also provides 
an exemption procedure, such as an exemption-certificate requirement, then, if 
the purchasing Party complies with such procedure, the providing Party shall not
collect such Tax during the effective period of such exemption. Such exemption 
shall be effective upon receipt of the exemption certificate or affidavit in 
accordance with the terms set forth in subsection 29.6.6. If Applicable Laws 
clearly exempts a purchase hereunder from a Tax, but does not also provide an 
exemption procedure, then the providing Party shall not collect such Tax if the 
purchasing Party (i) furnishes the providing Party with a letter signed by an 
officer requesting such an exemption and citing the provision in the Law which 
clearly allows such exemption and (ii) supplies the providing Party with an 
indemnification agreement, reasonably acceptable to the providing Party (e.g., 
                                                                         - - 
an agreement commonly used in the industry), which holds the providing Party 
harmless on an after-tax basis with respect to its forebearing to collect such 
Tax.

                                      57
<PAGE>
 
          29.6.6.   Notices for Purposes of this Subsection 29.6.  All notices, 
                    --------------------------------------------
affidavits, exemption-certificates or other communications required or permitted
to be given by either Party to the other, for purposes of this subsection 29.6, 
shall be made in writing and shall be delivered in person or sent by certified 
mail, return receipt requested, or registered mail, or a courier service 
providing proof of service, and sent to the addresses set forth in subsection 
29.10 as well as to the following:

     To Bell Atlantic:        Tax Administration
                              Bell Atlantic Network Services, Inc.
                              1717 Arch Street
                              30th Floor
                              Philadelphia, PA 19103

     To MFS:                  Corporate Tax Department
                              MFS Communications Company, Inc.
                              11808 Miracle Hills Drive
                              Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addressees
by giving notice is accordance with the terms of this subsection 29.6. Any
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT.  Neither Party shall assign this Agreement nor any of its 
rights or obligations hereunder without the prior written consent of the other 
Party, which consent shall not be unreasonably withheld. Any assignment or 
delegation in violation of this subsection 29.7 shall be void and ineffective 
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS.

          29.8.1  Except may otherwise be provided in this Agreement, each Party
shall submit on a monthly basis an itemized statement of charges incurred by the
other Party during the preceding month(s) for services rendered hereunder. 
Payment of billed amounts under this Agreement, whether billed on a monthly 
basis or as otherwise provided herein, shall be due, in immediately available 
U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2  Although it is the intent of both Parties to submit timely and
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or 
a waiver of the right to payment of the incurred charges, by the billing Party 
under this Agreement, and the billed Party shall not be entitled to dispute the 
billing Party statement(s) based on such Party's failure to submit them in a 
timely fashion.

          29.8.3  If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60) days 
of its receipt of the invoice containing such

                                      58

<PAGE>
 
disputed amount give notice to the Billing Party of the amounts it disputes 
("Disputed Amounts") and include in such notice the specific details and reasons
for disputing each item. The Non-Paying Party shall pay when due (i) all 
undisputed amounts to the Billing Party and (ii) all Disputed Amounts into an 
interest bearing escrow account with a third party escrow agent mutually agreed 
upon by the Parties.

            29.8.4    If the Parties are unable to resolve the issues related to
the Disputed Amounts in the normal course of business within ninety (90) days
after delivery to the Billing Party of notice of the Disputed Amounts, each of
the Parties shall appoint a designated representative that has authority to
settle the dispute and that is at a higher level of management than the persons
with direct responsibility for administration of this Agreement. The designated
representatives shall meet as often as they reasonably deem necessary in order
to discuss the dispute and negotiate in good faith in an effort to resolve such
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

            29.8.5    If the Parties are unable to resolve issues related to the
Disputed Amounts within forty-five (45) days after the Parties' appointment of
designated representatives pursuant to subsection 29.8.4, then either Party may
file a complaint with the Commission to resolve such issues or proceed with any
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus
applicable late fees, to be paid to either Party.

            29.8.6    The Parties agree that all negotiations pursuant to this
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state
rules of evidence.

            29.8.7    Any undisputed amounts not paid when due shall accrue
interest from the date such amounts were due at the lesser of (i) one and one-
half percent (1-1/2%) per month or (ii) the highest rate of interest that may be
charged under applicable law.

     29.9   DISPUTE RESOLUTION. Any dispute between the Parties regarding the
interpretation or enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial 
forum of competent jurisdiction.

     29.10  NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing and shall be (a) delivered personally, (b) 
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by 
telecopy to the following addresses of the Parties.

               To MFS:

                                      59
<PAGE>
 
            MFS Intelenet of Virginia, Inc.                           
            33 Whitehall St.                                         
            15/th/ Floor                                               
            New York, NY 10004                                       
            Attn: Director, Regulatory Affairs - Eastern Region      
            Facsimile: 212/843-3060                                  
                                                                     
            To Bell Atlantic:                                        
                                                                     
            Director - Interconnection Services                      
            Bell Atlantic Network Services, Inc.                     
            1320 N. Courthouse Road                                  
            9th Floor                                                
            Arlington, VA 22201                                      
            Facsimile: 703/974-2183                                  
                                                                     
            with a copy to:                                        
                                                                     
            Vice President and General Counsel                       
            Bell Atlantic - Virginia, Inc.                           
            600 East Main Street                                          
            24th Floor                                               
            Richmond, VA 23261                                       
            Facsimile: (804) 772-2143                                 

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual
receipt, (ii) the next business day when notice is sent via express mail or
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of telecopy.

     29.11  SECTION 252(I) OBLIGATIONS.

            29.11.1 If at any time during the term of this Agreement, either
Party enters into an agreement to provide an integrated package of services or
arrangements substantially similar to that described herein to another CLEC (in
the case of BA), or another incumbent LEC (in the case of MFS), operating within
the same state to which this Agreement applies, on terms significantly different
than those available under this Agreement (the "Other Agreement"), then the
other Party may opt to adopt, on a prospective basis only, the rates, terms and
conditions contained in the Other Agreement (i) in its entirety, or (ii) that
relate directly to any of the following individual services. Network Elements,
or arrangements, for its own reciprocal arrangements with the first Party,
including, without limitation, any term or volume commitments or network
architecture configurations:

                                      60


 
 



























<PAGE>
 
          (a)  Unbundled Loop Elements - Section 251(e)(3) of the Act (Section 
11 of this Agreement); or

          (b)  Collocation - Section 251(c)(6) of the Act (Section 13 of this 
Agreement); or

          (c)  Number Portability - Section 251(b)(2) of the Act (Section 14 of 
this Agreement); or

          (d)  Access to Rights of Way - Section 251(b)(4) of the Act (Section 
16 of this Agreement).

          (e)  transiting arrangements.

          29.11.2   To the extent the exercise of the foregoing options requires
a rearrangement of facilities by the providing Party, the opting Party shall be 
liable for the non-recurring charges associated therewith.

          29.11.3   The Party electing to exercise such option shall do so by 
delivering written notice to the first Party. Upon receipt of said notice by the
first Party, the Parties shall amend this Agreement to provide the same rates, 
terms and conditions to the notifying Party for the remaining term of this 
Agreement; provided, however, that the Party exercising its option under this 
subsection 29.11 must continue to provide the same services or arrangements to 
the first Party as required by this Agreement, subject either to the rates, 
terms, and conditions applicable to the first Party in its agreement with the 
third party or to the rates terms, and conditions of this Agreement, whichever 
is more favorable to the first Party in its sole determination.

          29.11.4   BA represents and warrants that as of the date of this
 Agreement, it has not entered into any comparable Interconnection agreement
 with any other CLEC in BA's service territory that is significantly more
 favorable than the terms contained herein. BA makes no warranty or
 representation with respect to its Interconnection arrangements with its
 affiliates or ITCs.

     29.12  JOINT WORK PRODUCT.  This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and 
shall be fairly interpreted in accordance with its terms and, in the event of 
any ambiguities, no inferences shall be drawn against either Party.

     29.13  NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY.  This Agreement 
is for the sole benefit of the Parties and their permitted assigns, and nothing 
herein express or implied shall create or be construed to create any third-party
beneficiary rights hereunder. Except for provisions herein expressly authorizing
a Party to act for another, nothing in this Agreement shall constitute a Party 
as a legal representative or agent of the other Party, nor shall a Party have 
the right or authority to assume, create or incur any liability or any 
obligation of any kind, express or implied, against or in the name or on behalf 
of the other Party unless otherwise expressly 

                                      61
<PAGE>
 
permitted by such other Party. Except as otherwise expressly provided in this 
Agreement, no Party undertakes to perform any obligation of the other Party, 
whether regulatory or contractual, or to assume any responsibility for the 
management of the other Party's business.

     29.14 NO LICENSE.

          29.14.1  Nothing in this Agreement shall be construed as the grant of
a license, either express or implied, with respect to any patent, copyright,
trademark, trade name, trade secret or any other proprietary or intellectual
property now or hereafter owned, controlled or licensable by either Party.
Neither Party may use any patent, copyrightable materials, trademark, trade
name, trade secret or other intellectual property right of the other Party
except in accordance with the terms of a separate license agreement between the
Parties granting such rights.

          29.14.2  Neither Party shall have any obligation to defend, indemnify
or hold harmless, or acquire any license or right for the benefit of, or owe any
other obligation or have any liability to, the other Party or its customers
based on or arising from any claim, demand, or proceeding by any third party
alleging or asserting that the use of any circuit, apparatus, or system, or the
use of any software, or the performance of any service or method, or the
provision of any facilities by either Party under this Agreement, alone or in
combination with that of the other Party, constitutes direct, vicarious or
contributory infringement or inducement to infringe, misuse or misappropriation
of any patent, copyright, trademark, trade secret, or any other proprietary or
intellectual property right of any Party or third party. Each Party, however,
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

          29.14.3  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE 
PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, ANY 
WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S 
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT 
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR 
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15 TECHNOLOGY UPGRADES. Nothing in this Agreement shall limit BA's 
ability to upgrade its network through the incorporation of new equipment, new 
software or otherwise. BA shall provide MFS written notice at least ninety (90) 
days prior to the incorporation of any such upgrades in BA's network that will 
materially affect MFS's service. MFS shall be solely responsible for the cost 
and effort of accommodating such changes in its own network.

     29.16  SURVIVAL. The Parties' obligations under this Agreement which by 
their nature are intended to continue beyond the termination or expiration of 
this Agreement shall survive the termination or expiration of this Agreement.

     29.17  ENTIRE AGREEMENT. The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other documents or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with

                                      62

     
<PAGE>
 
respect to the subject matter hereof, superseding all prior understandings, 
proposals and other communications, oral or written. Neither Party shall be 
bound by any preprinted terms additional to or different from those in this 
Agreement that may appear subsequently in the other Party's form documents, 
purchase orders, quotations, acknowledgments, invoices or other communications.

     29.18  COUNTERPARTS. This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19  MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No
modification, amendment, supplement to, or waiver of the Agreement or any of its
provisions shall be effective and binding upon the Parties unless it is made in
writing and duly signed by the Parties. A failure or delay of either Party to
enforce any of the provisions hereof, to exercise any option which is herein
provided, or to require performance of any of the provisions hereof shall in no
way be construed to be a waiver of such provisions or options.

     29.20 SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and inure 
to the benefit of the Parties and their respective legal successors and 
permitted assigns.

     29.21 PUBLICITY. Neither Party shall use the name of the other Party in 
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      63
<PAGE>
 
                                 SCHEDULE 12.3
                          SUPPORT SERVICES FOR RESALE
                          ---------------------------

1    BA OSS SERVICES
     ---------------

     1.1  DEFINITIONS
          -----------

     As used in this Schedule 12.3, the following terms shall have the meanings 
     stated below:

     1.1.1  "BA Operations Support Systems" means BA systems for pre-ordering, 
     ordering, provisioning, maintenance and repair, and billing.

     1.1.2  "BA OSS Services" means access to BA Operations Support Systems 
     functions. The term "BA OSS Services" includes, but is not limited to: (a)
     BA's provision of MFS Usage Information to MFS pursuant to Section 1.3
     below; and, (b) "BA OSS Information", as defined in Section 1.1.4 below.

     1.1.3  "BA OSS Facilities" means any gateways, interfaces, databases, 
     facilities, equipment, software, or systems, used by BA to provide BA OSS
     Services to MFS.

     1.1.4  "BA OSS Information" means any information accessed by, or disclosed
     or provided to, MFS through or as a part of BA OSS Services. The term "BA
     OSS Information" includes, but is not limited to: (a) any Customer
     Information related to a BA Customer or an MFS Customer accessed by, or
     disclosed or provided to, MFS through or as a part of BA OSS Services: and,
     (b) any MFS Usage Information (as defined in Section 1.1.6 below) accessed
     by, or disclosed or provided to, MFS.

     1.1.5  "BA Retail Telecommunications Services" means any Telecommunications
     Service that Bell Atlantic provides at retail to subscribers that are not
     Telecommunications Carriers. The term "BA Retail Telecommunications
     Service" does not include any exchange access service (as defined in
     Section 3(16) of the Act, 47 U.S.C. (S) 153(16)) provided by BA.

     1.1.6  "MFS Usage Information" means the usage information for a BA Retail 
     Telecommunications Service purchased by MFS under this Agreement that BA
     would record if BA was furnishing such BA Retail Telecommunications Service
     to a BA end-user retail Customer.


<PAGE>
 
     1.1.7  "Customer Information" means CPNI, as defined in the Act, of a
     Customer and any other non-public, individually identifiable information
     about a Customer or the purchase by a Customer of the services or products
     of a Party.

     1.2 BA OSS Services
         ---------------

     1.2.1  Upon request by MFS, BA shall provide to MFS, pursuant to Section
     251(c)(3) of the Act, 47 U.S.C. (S) 251(c)(3), BA OSS Services.

     1.2.2  Subject to the requirements of Applicable Laws, BA Operations 
     Support Systems, BA Operations Support Systems functions, BA OSS
     Facilities, BA OSS Information, and the BA OSS Services that will be
     offered by BA, shall be as determined by BA. Subject to the requirements of
     Applicable Laws, BA shall have the right to change BA Operations Support
     Systems, BA Operations Support Systems functions, BA OSS Facilities, BA OSS
     Information, and the BA OSS Services, from time-to-time, without the
     consent of MFS. Except as otherwise provided by this Agreement or
     Applicable Laws. BA will give MFS notice in writing or electronically
     (which may be by giving MFS access to a database or an Internet site that
     contains the applicable information, or by other electronic means) of
     material modification of the operation of BA OSS Services furnished under
     this Agreement at least sixty (60) days prior to the time the material
     modification becomes effective.

     1.3 MFS Usage Information
         ---------------------

     1.3.1  Upon request by MFS, BA shall provide to MFS, pursuant to Section 
     251(c)(3) of the Act, 47 U.S.C. (S) 251(c)(3), MFS Usage Information.

     1.3.2  MFS Usage Information will be available to MFS through the 
     following:

            (a)  Daily Usage File on Data Tape.

            (b)  Daily Usage File through Network Data Mover ("NDM").

            (c)  Daily Usage File through Centralized Message Distribution
     System ("CMDS").

     1.3.3.1  MFS Usage Information will be provided in a Bellcore Exchange 
     Message Records ("EMR") format.

     1.3.3.2  Daily Usage File Data Tapes provided pursuant to Section 1.3.2(a) 
     above will be issued each day, Monday through Friday, except holidays
     observed by BA.

<PAGE>
 
     1.3.4  Except as stated in this Section 1.3. subject to the requirements of
     Applicable Laws, the manner in which, and the frequency with which, MFS
     Usage Information will be provided to MFS shall be determined by BA.

     1.4    Access to and Use of BA OSS Facilities
            --------------------------------------

     1.4.1  BA OSS Facilities may be accessed and used by MFS only to the extent
     necessary for MFS's access to and use of BA OSS Service pursuant to this 
     Agreement.

     1.4.2  BA OSS Facilities may be accessed and used by MFS only to provide 
     Telecommunications Services to MFS Customers.

     1.4.3  MFS shall restrict access to and use of BA OSS Facilities to MFS.  
     This Schedule 12.3 does not grant to MFS any right or license to grant
     sublicenses to other persons, or permission to other persons (except MFS's
     employees, agents and contractors, in accordance with Section 1.4.7 below),
     to access or use BA OSS Facilities.

     1.4.4  MFS shall not (a) alter, modify or damage the BA OSS Facilities     
     (including, but not limited to, BA software), (b) copy, remove, derive,
     reverse engineer, or decompile, software from the BA OSS Facilities, or (c)
     obtain access through BA OSS Facilities to BA databases, facilities,
     equipment, software, or systems, which are not offered for MFS's use under
     this Schedule 12.3.

     1.4.5  MFS shall comply with all practices and procedures established by BA
     for access to and use of BA OSS Facilities (including, but not limited to,
     BA practices and procedures with regard to security and use of access and
     user identification codes).

     1.4.6  All practices and procedures for access to and use of BA OSS
     Facilities, and all access and user identification codes for BA OSS
     Facilities: (a) shall remain the property of BA: (b) shall be used by MFS
     only in connection with MFS's use of BA OSS Facilities permitted by this
     Schedule 12.3; and, (c) shall be treated by MFS as Proprietary Information
     of BA pursuant to subsection 29.4 of the Agreement.

     1.4.7  MFS's employees, agents and contractors may access and use BA OSS 
     Facilities only to the extent necessary for MFS's access to and use of the
     BA OSS Facilities permitted by this Agreement. Any access to or use of BA
     OSS Facilities by MFS's employees, agents, or contractors, shall be subject
     to the provisions of the Agreement, including, but not limited to,
     subsection 29.4 thereof and Sections 1.4.6 and 1.5.3.3 of this Schedule
     12.3.

     1.5    BA OSS Information
            ------------------



<PAGE>
 


1.5.1    Subject to the provisions of this Agreement and Applicable Laws. BA 
grants to MFS a non-exclusive license to use BA OSS Information.

1.5.2    All BA OSS Information shall at all times remain the property of BA.
Except as expressly stated in this Schedule 12.3 MFS shall acquire no rights
in or to any BA OSS Information.

1.5.3.1  The provisions of the Section 1.5.3 shall apply to all BA OSS 
Information, except (a) MFS Usage Information (b) CPNI of MFS, and (c) CPNI of a
BA Customer or an MFS Customer, to the extent the Customer has authorized MFS to
use the Customer Information.

1.5.3.2  BA OSS Information may be accessed and used by MFS only to provide 
Telecommunications Services to MFS Customers.

1.5.3.3  MFS shall treat BA OSS Information that is designated by BA, through 
written or electronic notice (including, but not limited to, through the BA OSS 
Services), as "Confidential" or "Proprietary" as Proprietary Information of BA 
pursuant to subsection 29.4 of the Agreement.

1.5.3.4  Except as expressly stated in this Schedule 12.3, this Agreement does 
not grant to MFS any right or license to grant sublicenses to other persons, or 
permission to other persons (except MFS's employees, agents or contractors, in 
accordance with Section 1.5.3.5 below), to access, use or disclose BA OSS 
Information.

1.5.3.5  MFS's employees, agents and contractors may access, use and disclose BA
OSS Information only to the extent necessary for MFS's access to, and use and 
disclosure of, BA OSS Information permitted by this Schedule 12.3. Any access 
to, or use or disclosure of, BA OSS Information by MFS's employees, agents or 
contractors, shall be subject to the provisions of this Agreement, including, 
but not limited to, subsection 29.4 of the Agreement and Section 1.5.3.3 above.


1.5.3.6  MFS's license to use BA OSS Information shall expire upon the earlier 
of: (a) termination of the license in accordance with this Schedule 12.3: or (b)
expiration or termination of the Agreement.

1.5.3.7  All BA OSS Information received by MFS shall be destroyed or returned 
by MFS to BA, upon expiration, suspension or termination of the license to use 
such BA OSS Information.

1.5.4    Unless sooner terminated or suspended in accordance with the Agreement 
or this Schedule 12.3 (including, but not limited to, subsection 22.3 of the 









<PAGE>
 
Agreement and Section 1.6.1 below), MFS's access to BA OSS Information through
BA OSS Services shall terminate upon the expiration or termination of the
Agreement.

1.5.5.1  BA shall have the right (but not the obligation) to perform at BA's
expenses (provided that there will be no charge to BA for reasonable access to
MFS' employees, books, records, documents and facilities) an audit of MFS upon
three (3) full business days notice to MFS to ascertain whether MFS is complying
with the requirements of Applicable Laws and this Agreement with regard to MFS's
access to, and use and disclosure of, BA OSS Information.

1.5.5.2  Without in any way limiting any other right BA may have under the 
Agreement or Applicable Laws. BA shall have the right but not the obligation) to
monitor MFS's access to and use of BA OSS Information which is made available by
BA to MFS pursuant to this Agreement, to ascertain whether MFS is complying with
the requirements of Applicable Laws and this Agreement, with regard to MFS's
access to, and use and disclosure of, such BA OSS Information. The foregoing
right shall include, but not be limited to, the right (but not the obligation)
to electronically monitor at BA's expense (provided that there will be no charge
to BA by MFS to perform this activity). MFS's access to and use of BA OSS
Information which is made available by BA to MFS through BA OSS Facilities.

1.5.5.3  Information obtained by BA pursuant to this Section 1.5.5 shall be 
treated by BA as Proprietary Information of MFS pursuant to subsection 29.4 of
the Agreement; provided that, BA shall have the right (but not the obligation) 
to use and disclose information obtained by BA pursuant to this Section 1.5.5 to
enforce BA's rights under this Agreement or Applicable Laws.

1.5.6  MFS acknowledges that the BA OSS Information, by its nature, is updated
and corrected on a continuous basis by BA, and therefore that BA OSS Information
is subject to change from time to time.

1.6 Liabilities and Remedies
    ------------------------

1.6.1  Any breach by MFS, or MFS's employees, agents or contractors, of the 
provisions of Sections 1.4 or 1.5 above shall be deemed a material breach of the
Agreement. In addition, if MFS or an employee, agent or contractor of MFS at
any time breaches a provision of Sections 1.4 or 1.5 above and such breach
continues for more than fifteen (15) days after written notice thereof from BA,
then, except as otherwise required by Applicable Laws, BA shall have the right,
upon notice to MFS, to suspend the license to use BA OSS Information granted by
Section 1.5.1 above and/or the provision of BA OSS Services, in whole or in 
part.
<PAGE>
 
     1.6.2   MFS agrees that BA would be irreparably injured by a breach of
     Sections 1.4 or 1.5 above by MFS or the employees, agents or contractors of
     MFS, and that BA shall be entitled to seek equitable relief, including
     injunctive relief and specific performance, in the event of any such
     breach. Such remedies shall not be deemed to be the exclusive remedies for
     any such breach, but shall be in addition to any other remedies available
     under this Agreement or at law or in equity.

     1.7     Relation to Applicable Laws
             ---------------------------

     The provisions of Sections 1.4, 1.5 and 1.6 above shall be in addition to
     and not in derogation of any provisions of Applicable Laws, including, but
     not limited to, 47 U.S.C. (S) 222, and are not intended to constitute a
     waiver by BA of any right with regard to protection of the confidentiality
     of the information of BA or BA Customers provided by Applicable Laws.

     1.8     Cooperation
             -----------

     MFS, at MFS's expense, shall reasonably cooperate with BA in using BA OSS
     Services. Such cooperation shall include, but not be limited to, the
     following:

     1.8.1   Upon request by BA, MFS shall by no later than the fifteenth (15th)
     day of the month preceding the first calendar month of each calendar
     quarter submit to BA reasonable, good faith estimates (by geographic area
     designated by BA) of the volume of each BA Retail Telecommunications
     Service for which MFS anticipates submitting orders in each week of the
     next calendar quarter.

     1.8.2   MFS shall participate in cooperative testing of BA OSS Services and
     shall provide assistance to BA in identifying and correcting mistakes,
     omissions, interruptions, delays, errors, defects faults, failures or other
     deficiencies, in BA OSS Services. The Parties will jointly agree upon the
     schedule for such testing and the tests that will be conducted.
     
     1.9     BA Access to Information Related to MFS Customers
             -------------------------------------------------

     BA shall have the right to access, use and disclose information related to
     MFS Customers that is in BA's possession (including, but not limited to, in
     BA OSS Facilities) to the extent such access, use and/or disclosure has
     been authorized by the MFS Customer in the manner required by Applicable
     Laws.

2.   BELL ATLANTIC PRE-OSS SERVICES
     ------------------------------

     2.1     As used in this Schedule 12.3. "BA Pre-OSS Service" means a service
     that allows the performance of an activity that is comparable to an
     activity to be performed through a BA OSS Service and that BA offers to
     provide to MFS. The term "BA Pre-OSS Service" includes, but is not limited
     to, the activity of placing
<PAGE>
 
     orders for BA Telecommunications Services through a telephone facsimile
     communication. Prior to purchasing BA OSS Services, MFS may purchase BA 
     Pre-OSS Services.

     2.2 Subject to the requirements of Applicable Laws, the BA Pre-OSS Services
     that will be offered by BA shall be as determined by BA and BA shall have
     the right to change BA Pre-OSS Services, from time-to-time, without the
     consent of MFS. Except as otherwise provided by this Agreement or
     Applicable Laws, BA will give MFS notice in writing or electronically
     (which may be by giving MFS access to a database or an Internet site that
     contains the applicable information, or by other electronic means) of
     material modification of the operation of BA Pre-OSS Services furnished
     under this Agreement at least thirty (30) days prior to the time the
     material modification becomes effective.

     2.3 Subject to the requirements of Applicable Laws, the prices for BA Pre-
     OSS Services shall be as determined by BA and shall be subject to change by
     BA from time-to-time.

     2.4 The provisions of Section 1.5 through 1.9 above shall also apply to BA
     Pre-OSS Services. For the purposes of this Section 2.4: (a) references in
     Sections 1.5 through 1.9 above to BA OSS Services shall be deemed to
     include BA Pre-OSS Services; and, (b) references in Section 1.5 through 1.9
     above to BA OSS Information shall be deemed to include information made
     available to MFS through BA Pre-OSS Services.


3.   RATES AND CHARGES
     -----------------

     3.1 The prices for the foregoing services shall be as set forth in BA's
     Tariffs or, in the absence of an applicable BA Tariff price, in Exhibit A
     or, if not set forth in either, as may be determined by BA from time to
     time. If BA at any time offers a resale support service the prices for
     which are not stated in BA's Tariffs or Exhibit A and MFS elects to
     purchase such service. BA shall have the right to revise Exhibit A to add
     such prices: provided that, if the resale support service is already being
     used by MFS at the time BA revises Exhibit A to add such prices, except as
     otherwise required by this Agreement or Applicable Laws, the revision shall
     not become effective until BA has given MFS thirty (30) days prior notice
     of the revision.







 
<PAGE>
 

                                                                       Exhibit A


                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.


                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   -------------------------------------

 A.     BA SERVICES, FACILITIES, AND ARRANGEMENTS:

<TABLE>
<CAPTION>
- ---------------------------------------------------------------------------------------------------
       BA SERVICE                                 NON-RECURRING          RECURRING
       ----------                                 -------------          ---------
- ---------------------------------------------------------------------------------------------------
<S>                                               <C>                    <C>
 1.a.  Entrance facilities, and transport, as     Per interstate [BA FCC #1 sec. 6.9.1.] and
       appropriate, for Interconnection at        (proposed) intrastate [BA-VA SCC 217
       BA End Office, Tandem Office,              sec. 6.8.2] access tariffs for Feature Group
       Serving Wire Center, or other Point        D Service/2/
       of Interconnection

                                                  Illustrative:

                                                    Interstate non-recurring: $1, plus $1
                                                  switched access connection charge per
                                                  trunk; DS-1 entrance facility $210-
                                                  $212/mo.

                                                    Intrastate nonrecurring: $895 for first DS-
                                                  1, $280 for additional, plus $25 switched
                                                  access connection charge per trunk; DS-1
                                                  entrance facility $270/mo.
- ---------------------------------------------------------------------------------------------------
 1.b.  Collocation and related services for       Per interstate [BA FCC 1 sec. 19] and
       Interconnection at BA End Office,          intrastate access tariffs/3/
       Tandem Office, or Serving Wire
       Center
- ---------------------------------------------------------------------------------------------------
</TABLE>

___________________
/1/       Rates listed herein for services, facilities, or arrangements that are
marked with an asterisk (*) are fixed pursuant to Section 20 of the Agreement
for the initial term of the Agreement, as set forth in Section 22 of the
Agreement. Rates for services, facilities, or arrangements that are not marked
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.
/2/       Pending approval of the BA intrastate local transport restructure
tariff, intrastate access services subject to the pending tariff will be charged
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at
either Party's request.
/3/       Pending approval of the BA intrastate collocation tariff to be filed
no later December 31, 1996, all collocation services shall be charged at rates
found in BA FCC 1 sec. 19.

                                       1
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------------------------------
     BA SERVICE                        NON-RECURRING                           RECURRING
     ----------                        -------------                           ---------
- ------------------------------------------------------------------------------------------------------------------------------------
<S>                                    <C>                                     <C> 
1.c. Tandem transit arrangements       Per tariffs cited in    
     (for Interconnection between      sections 1.a. and 1.b. above, as        Per interstate [BA FCC 1 sec. 6.9.1.B] and      
     MFS and carriers other than BA)   applicable; separate trunks required    (proposed) intrastate [BA-VA SCC 217 sec. 6.8.2.B]
                                       for IXC subtending trunks/4/            for tandem switching and tandem switched transport,
                                                                               as applicable/5/   
                                                                               

                                                                               Illustrative:
                                     
                                                                               Interstate, (proposed) intrastate tandem switching 
                                                                               $.000999/mou, tandem switched transport $.000195/mou
                                                                               plus $.000045/mou/mile
- ------------------------------------------------------------------------------------------------------------------------------------
1.d. 911 Interconnection               Per tariffs cited in 1.a., 1.b., and 1.c. above, as applicable, for entrance facility plus
                                       applicable transport, or Collocation Arrangement at 911 tandem
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 


___________________________________________
/4/    See note 2 above.
/5/    See note 2 above.

                                       2

                                                                 
<PAGE>
 
<TABLE> 
<CAPTION> 
 
- ------------------------------------------------------------------------------------------------------------------------------------
      BA SERVICE                                NON-RECURRING                            RECURRING
      ----------                                -------------                            ---------
<S>                                             <C>                                      <C> 
1.e.  Directory assistance Interconnection      Intrastate per (proposed) BA-VA SCC      Intrastate per (proposed) BA-VA SCC 217
                                                217 sec. 9.6.B (transport)/6/            sec. 9.6.B:  
                                                
                                                                                         Illustrative: 

                                                                                           Per call rate $.000092 fixed, $.000021
                                                                                         per mile, $.000462 tandem switching,
                                                                                         $.003705 interconnection

                                                Interstate per BA FCC 1 sec. 9.6.B       Interstate per BA FCC 1 sec. 9.6.B 

                                                                                         Illustrative: 

                                                                                           Per call rate $.000082 fixed, $.000019
                                                                                         per mile, $.000353 tandem switching, 
                                                                                         $.002311 interconnection
- ------------------------------------------------------------------------------------------------------------------------------------
1.f.  Operator services (call completion)       Per separate contract
      Interconnection
- ------------------------------------------------------------------------------------------------------------------------------------
2.    Unbundled elements                        Available as listed herein and in interstate and intrastate tariffs, and pursuant
                                                to Section 11. of the Agreement
- ------------------------------------------------------------------------------------------------------------------------------------
3.    Poles, ducts, conduits, ROW               Per contract rates pursuant to 47 U.S.C. sec. 224
                         
                                                Illustrative:

                                                  Duct (Northern Virginia) $4.50/ft/yr.
                                                  Pole $4.46/attachment/yr.
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 


____________________________________
/6/   See note 2 above
/7/   See note 2 above.

                                       3
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE               NON-RECURRING            RECURRING
     ----------               -------------            ---------
- --------------------------------------------------------------------------------
4.a. Local loop transmission* Permanent rates to be    Permanent rates to be 
                              determined by            determined by appropriate
       Unbundled Local Loop   arbitral body. Interim   arbitral body. Interim   
       Element                rates will apply until   rates will apply until   
                              the permanent rates are  the permanent rates are 
       Cross Connection to    determined./8/           determined./9/         
       POTS loop                                                                
                                                                               

- --------------------------------------------------------------------------------
4.b. Special construction     As applicable per BA-VA SCC 203 sec.2
     charges
- --------------------------------------------------------------------------------
4.c. Central office           Per interstate [BA FCC 1 sec.13.2 or sec.19.5]
     charges (during normal   tariff.
     working hours)

- --------------------------------------------------------------------------------
5.a. Trunk Side local      
     transport

       DS-1 transport         Per interstate [BA FCC 1 sec.6.9.1.C] and 
                              (proposed) intrastate [BA-VA SCC 217 sec.6.8.2.C]
                              tariffs
                    
                              Illustrative recurring:

                                Interstate $60/mo. fixed, $17.70/mile/mo.

                                Intrastate $75/mo. fixed, $30/mile/mo.
- --------------------------------------------------------------------------------
5.b. DS-3 transport           Tariff reference see 5.a. above.

                              Illustrative recurring:

                                Interstate, intrastate $900/mo. fixed. 
                              $180/mile/mo.
- --------------------------------------------------------------------------------

_______________________
/8/  Interim rates will be based on the following order of precedence (i)
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in the
state, (iii) any Commission recommendation, or (iv) mutual agreement of the
Parties.

/9/  See preceding note.
/10/ See note 2 above.

                                       4

<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICES                 NON-RECURRING                 RECURRING  
     -----------                 -------------                 ---------
- --------------------------------------------------------------------------------
6.   Local switching*  

     POTS switch Port            $6/service order              $1.50/mon plus
                                 plus $6/Port                  usage per tariff,
                                                               minus wholesale
                                                               discount per 
                                                               section 14 below
- --------------------------------------------------------------------------------
7.a. Operator services

      911 service (data entry;   No charge  
     database maintenance)*
- --------------------------------------------------------------------------------
7.b.  Directory assistance       Per tariff or separate        Per tariff or  
                                 contact; branding             separate contract
                                 available
                                                               Illustrative 
                                                               tariff rates:

                                                               Interstate [BA 
                                                               FCC 1 sec. 9.6],
                                                               $.275-.288 per 
                                                               call 

                                                               Intrastate 
                                                               (proposed) [BA-VA
                                                               SCC 217 sec. 9.6.
                                                               A], $.25 per call

                                                               Directory 
                                                               transport per 
                                                               section 1.e. 
                                                               above
- --------------------------------------------------------------------------------
7.c.  Operator call              Per separate contract; branding available     
      completion
- --------------------------------------------------------------------------------
8.a. White pages directory       $5.00 per primary listing     No charge 
     listings*                   per number
- --------------------------------------------------------------------------------
8.b.  Books & delivery           No charge for normal numbers of books delivered
     (annual home area           to end users: bulk deliveries to CLEC per
     directories only)*          separate arrangement 
- --------------------------------------------------------------------------------

                                       5

<PAGE>
 

<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ----------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
8.c.  Additional listings, changes           Per tariff [BA-VA              Per tariff [BA-VA SCC 
     to listing, non-listed, non-            SCC 203 sec. 4]                203 sec. 4]
     published, and other extra services
                                             Illustrative:                  Illustrative:

                                              Additional listing:          Additional listing:  
                                             $9 residence: $17             $1.12/mo. residence, 
                                             business                      $1.42/mo. business    
                                                                            
                                              Change to listing:           
                                             $9 residence: $17              Non-list:            
                                             business                       $1.06//mo. residence 
                                                                            or business           
                                              Non-list:                    
                                             $9 residence: $17              Non-published:     
                                             business                       $1.71/mo. residence
                                                                            or business         
                                              Non-published:
                                             $9 residence: $17
                                             business
- ---------------------------------------------------------------------------------------------------- 
9.   Access to telephone numbers (NXX
     codes issued per ICCF Code              No charge
     Administration Guidelines)*        
- ----------------------------------------------------------------------------------------------------  
10.a SS7 Interconnection                     Per interstate [BA             Per interstate [BA
                                             FCC 1 sec. 6.9.1.G]            FCC 1 sec. 6.9.1.L]
                                             and intrastate [BA-            and intrastate [BA-
                                             VA SCC 217 sec.                VA SCC 217 sec.
                                             6.8.2.C] tariff                6.8.2.G] tariff 

     
                                                                            Illustrative:
          
                                                                             STP ports,
                                                                            $900/mo.;
                              
                                                                             STP access,
                                                                            $3.50/mile/mo. to
                                                                            $5.72/mile/mo.
- ----------------------------------------------------------------------------------------------------
</TABLE> 
  
                                       6
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
10.b LIDB Interconnection                    Per tariff [BA FCC             Per tariff [BA FCC 
                                             1 sec. 6.9.1M]                 1 sec. 6.9.1M]     
          
                                             Illustrative:                  Illustrative"
                              
                                              Originating point              Query validation
                                             code, $125                     $.04/query

                                                                             Query transport
                                                                            $.0002/query
- ------------------------------------------------------------------------------------------------
10.c 800/888 data base Interconnection       No separate charge             Per interstate [BA
                                             (included in FGD               FCC 1 sec.
                                             trunk and STP links)           6.9.2.A.1], and
                                                                            intrastate [BA-VA
                                                                            SCC 217 sec.
                                                                            6.8.2.K]tariffs

                                                                            Illustrative:

                                                                             Interstate basic
                                                                            query,
                                                                            $.003105/query;
                                                                            vertical feature
                                                                            package,
                                                                            $.000337/query

                                                                             Intrastate basic 
                                                                            query,
                                                                            $.003089/query;
                                                                            vertical feature
                                                                            package,
                                                                            $.000327/query
- ------------------------------------------------------------------------------------------------
11.a Interim number portability through      service order per              $3/mo. per number
     co-carrier call forwarding              location $30                   for up to 10 paths;
                                                                            $.40/mo. per 
                                             installation per               additional path
                                             number $35 (unless
                                             installed with 
                                             unbundled loop)
               
                                             installation per 
                                             separate path
                                             arrangement $20
- ------------------------------------------------------------------------------------------------
</TABLE> 

                                       7
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
11.b  Access pass-through to number                                         In accordance with
     portability purchaser*                                                 section 14.5 of
                                                                            Agreement.
- ------------------------------------------------------------------------------------------------
12.  Local dialing parity*                   No charge
- ------------------------------------------------------------------------------------------------
13.a Reciprocal call termination

      Local Traffic delivered to Bell
     Atlantic Interconnection Point

      First year*               
                                                                            $.009/mou
    -------------------------------------------------------------------------------------------- 
      After first year*                                                     In accordance with 
                                                                            note 14 below
- ------------------------------------------------------------------------------------------------
13.b  Access charges for termination of                                     Per interstate and
     intrastate and interstate Toll Traffic                                 intrastate access
                                                                            tariffs (charged in
                                                                            conjunction with
                                                                            Local Traffic, using
                                                                            PLU and PIU, as 
                                                                            appropriate)
- ------------------------------------------------------------------------------------------------
14.a Wholesale rates for resale of           Percentage discount from retail tariff/12/
                                             --------------------------------------
     telecommunications services
     provided to end users/11/
- ------------------------------------------------------------------------------------------------
14.b Resale of retail Telecommunications     21.3% or discount as determined by further
     Services if MFS provides its own        Commission order.
     Operator Services

- ------------------------------------------------------------------------------------------------
14.c Resale of retail Telecommunications     18.5% or discount as determined by further
     Services if MFS uses BA Operator        Commission order.
     Services.
- ------------------------------------------------------------------------------------------------
</TABLE> 


____________________

/11/      Excludes telecommunications services designated primarily for
wholesale, such as switched and special access, and, subject to Section 12 of
the Agreement, the following additional arrangements that are not subject to
resale: limited duration (90 days or less) promotional offerings, public coin
telephone services, and technical and market trials. Taxes shall be collected
and remitted by the reseller and BA in accordance with legal requirements and as
agreed between the Parties. Surcharges (e.g., 911 telecommunications relay
service, universal service fund) shall be collected by the reseller and either
remitted to the recipient agency or NECA, or passed through to BA for remittance
to the recipient agency or NECA, as appropriate and agreed between the Parties.
End user common line charges shall be collected by the resellers and remitted to
BA.

/12/      Pending establishment of mechanized billing procedures adapted to 
resale, the Parties will agree upon a composite "bottom-of-the-bill" discount 
that reflects the discounts and exclusions identified herein, and such other 
adjustments as the Parties agree.

                                       8

<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING            RECURRING
     ----------                    -------------            ---------
- --------------------------------------------------------------------------------
15.  Access to BA OSS/13/          
- --------------------------------------------------------------------------------
15.a Access to Pre-Ordering OSS                             $.26/Query
- --------------------------------------------------------------------------------
15.  Access to Ordering OSS                                 $4.53/Transaction
b
- --------------------------------------------------------------------------------
15.c Access to Provisioning OSS                             Included in Ordering
- --------------------------------------------------------------------------------
15d. Access to Maintenance &                                $1.23/Trouble Ticket
     Repair OSS
- --------------------------------------------------------------------------------
15e. Access to Billing OSS; CD-ROM                          $261.04/CD-ROM
1
- --------------------------------------------------------------------------------
15e. Access to Billing OSS; Daily 
 .2   Usage File
       Existing Message Recording                     
 
                                                            $.000274/Message
- --------------------------------------------------------------------------------
15e. Access to Billing OSS; Daily
     Usage
 .3   File Delivery
       Data Tape                   $64.96/Programming Hour  $20.11/Tape

       Network Data Mover          Not applicable           $.000099/Message

       CMDS                        $64.96/Programming Hour  $.000099/Message
- --------------------------------------------------------------------------------
15e. Access to Billing OSS; Daily  
     Usage
 .4   File Transport
       9.6 kb Communications Port  $8,335.27/Port           $10.84/Month
- --------------------------------------------------------------------------------

___________________
/13/ The rates for BA OSS Services that appear in Section 15 above shall apply 
until the earlier of August 15, 1997 or the date the Commission approves rates 
for BA OSS Services. If the Commission approves rates for BA OSS Services on or 
before August 15, 1997, the rates approved by the Commission will apply from the
date they are approved by the Commission until any subsequent change in rates 
becomes effective in accordance with this Agreement.

     If by August 15, 1997 the Commission has not approved rates for BA OSS 
Services, from August 16, 1997 until such time as the Commission approves rates
for BA OSS Services. BA will track the usage of BA OSS Services by MFS. When 
the Commission approves rates for BA OSS Services, those rates will apply from 
August 16, 1997 until any subsequent change in rates becomes effective in 
accordance with this Agreement.

     MFS reserves the right to at any time prior to the above-mentioned 
Commission approval of rates for BA OSS Services initiate or participate in a 
proceeding before the Commission or other governmental entity of appropriate 
jurisdiction to obtain a determination as to the lawfulness of the rates stated 
above in Section 15 for Bell Atlantic OSS Services. However, until such time as 
the Commission or other governmental entity of appropriate jurisdiction, in an 
order that is binding from Bell Atlantic, requires Bell Atlantic to change or 
delete the rates stated above in Section 15 for Bell Atlantic OSS Services,
MFS agrees to pay such rates as provided in this Footnote.

     When rates for BA OSS Services are approved by the Commission Section 15 
above shall be amended by the Parties to state such rates.

                                       9
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING                 RECURRING
     ----------                    -------------                 ---------
- --------------------------------------------------------------------------------
       56 kb Communications Port   $34,494.62/Port               $29.93/Month

       256 kb Communications Port  $57,422.87/Port               $29.93/Month
       
       T1 Communications Port      $204,901.39/Port              $380.18/Month

       Line Installation           $64.96/Programming Hour/Port  Not applicable

       Port Set-up                 $10.43/Port                   Not applicable

       Network Control Programming $64.96/Programming Hour/Port  Not applicable
       Coding
- --------------------------------------------------------------------------------

                                      10

<PAGE>
 
           MFS SERVICES, FACILITIES, AND ARRANGEMENTS:
- --------------------------------------------------------------------------------
          MFS SERVICE                   NON-RECURRING            RECURRING
          -----------                   -------------            ---------
- --------------------------------------------------------------------------------
1.a.      Interim Number Portability    
          through co-carrier call 
          forwarding*
     
           Number portability*          $30/service order.       $3/mo. for ten 
                                        $35/number (not ordered  paths per 
                                        with ULL)                number; plus 
                                                                 $.40/mo.per 
                                                                 additional path
                                        $20 per additional path
                                        order
- --------------------------------------------------------------------------------
1.b.        Access pass-through to number                        In accordance 
          portability purchaser*                                 with sec. 14.5 
                                                                 of Agreement
- --------------------------------------------------------------------------------
2.        Local dialing parity*         No charge
- --------------------------------------------------------------------------------
3.a.      Reciprocal call termination

           Local Traffic delivered to  
           MFS Interconnection Point*

          

           First year*                                           $.009/mou
         -----------------------------------------------------------------------
           After first year*                                     In accordance 
                                                                 with note 14 
                                                                 below
- --------------------------------------------------------------------------------
3.b.        Access charges for                                   Per MFS 
          termination of intrastate and                          interstate and
          interstate Toll Traffic                                intrastate
                                                                 access rates
                                                                 (charged in
                                                                 conjunction
                                                                 with Local
                                                                 Traffic, using
                                                                 PLU and PIU, as
                                                                 appropriate)
- --------------------------------------------------------------------------------
4.        All other MFS services        Available at MFS tariffed or otherwise
          available to BA for purposes  generally available rates, not to exceed
          of effectuating local         BA rates for equivalent services  
          exchange competition          available to MFS 
- --------------------------------------------------------------------------------
5.         Other Services

          Information Service billing   No charge                $.03 per call
          fee    
- --------------------------------------------------------------------------------

                                      11

<PAGE>
 
A.   Charges by BA
     -------------
     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA
          Access Tandem: $.009 per mou
     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou
     Note: All BA-IPs identified in Schedule 4.0 as of the Effective Date are 
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs 
     shall be subject to the rate of $.009 per mou.

B.   Charges by MFS
     --------------
1.   Single-tiered interconnection structure:
     MFS's rates for the termination of BA's Local Traffic under the 
     single-tiered interconnection structure shall be recalculated once each 
     year on each anniversary of the Effective Date (the "Rate Determination 
     Date"). The initial Rate Determination Date shall be the first anniversary 
     of the Effective Date. The methodology for recalculating the rates is as 
     follows:
               LSWC/Access Tandem Minutes = Total minutes of use of Local 
               Traffic delivered by MFS to the BA LSWC or BA Access Tandem for 
               most recent billed month.
               End Office Minutes = Total minutes of use Local Traffic delivered
               by MFS directly to the terminating BA End Office for most recent
               billed month.
               Total Minutes = Total minutes of use of Local Traffic delivered 
               by MFS to BA for most recent billed month.
               MFS Charge at the M-IP =
               (LSWC/Access Tandem Minutes X $.009) + (End Office Minutes X 
               ------------------------------------------------------------
               $.007)
               ------     
                                 Total Minutes
2.   Multiple-tiered interconnection structure (if offered by MFS to any 
     carrier)
     (a) Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009
     (b) Local Traffic delivered to terminating MFS End Office/node: $.007

C.   Miscellaneous Notes
     -------------------
1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended,
and/or (ii) where the Tandem Office that it subtends is not located within 25
miles of the Tandem Office that is subtended by the terminating End Office, then
such Party shall (x) in addition to paying the LSWC/Access Tandem termination
rate described above, purchase the necessary facilities from the terminating
Party to transport such Traffic to a qualifying LSWC or Access Tandem that is
not subject to either conditions (i) or (ii) above, (y) purchase such other
service(s) as the terminating Party may offer under applicable tariff to remedy
such condition(s), or (z) enter into a new compensation arrangement as the
Parties may agree. Notwithstanding the foregoing, nothing in this Agreement
shall obligate BA to provide switching services at a LSWC when it functions as
such.

                                      12 





   
<PAGE>
 
2.   In the event the two-tiered rate structure described above is modified
pursuant to Applicable Law to a single rate structure. BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting
Local Traffic it receives at its LSWC to the first point of switching in its
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure
set forth above is intended by the Parties to be a Local Traffic termination 
rate for Interconnection to the M-IP within each LATA that is reciprocal and 
equal to the actual rates that will be charged by BA to MFS under the 
two-tiered Local Traffic termination rate structure described above that will 
apply after the first anniversary of the Effective Date. The single MFS 
termination rate is also intended to provide financial incentives to MFS to 
deliver traffic directly to BA's terminating End Offices once MFS's traffic 
volumes reach an appropriate threshold. The Parties agree that the Reciprocal 
Compensation rate(s) set forth herein recover a reasonable approximation of 
each Party's additional costs of terminating calls that originate on the 
network facilities of the other Party.

                                      13

  




<PAGE>
 

                                  APPENDIX 2

<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA

     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
than the listed Dates.

- --------------------------------------------------------------------------------
 LATA IN VIRGINIA     MILESTONE                                      DATE
- --------------------------------------------------------------------------------
 LATA 236             LATA Start Date ("SD")                         7/21/98
- --------------------------------------------------------------------------------
                      SS7 Certification, Collocation, and NXX(s)     8/19/98
                      Applied For
- --------------------------------------------------------------------------------
                      Parties Agree on Initial Network Design        8/24/98
- --------------------------------------------------------------------------------
                      Valid Access Service Request(s) ("ASRs") and   TBD
                      Routing Information Received by BA
- --------------------------------------------------------------------------------
                      Collocation Arrangements Complete for Trunk    N/A
                      Interconnection and IDLC for ULLs
- --------------------------------------------------------------------------------
                      All Trunks Tested and Turned Up; SS7 Certifi-  11/20/98
                      cation Achieved; /1/  VG ULL Capability 
                      Available
- --------------------------------------------------------------------------------
                      Call-through Testing Completed;                12/11/98  
                      "Interconnection Activation Date"  
- --------------------------------------------------------------------------------
                           

     Failure of a Party or the Parties to meet an earlier Milestone Date shall
not relieve either Party of the responsibility to make its best efforts to meet
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that,
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when
Focal has an effective Tariff for business Telephone Exchange Service in the
Commonwealth of Virginia and has a significant number of Telephone Exchange
Service in the Commonwealth of Virginia and has a significant number of 
Telephone Exchange Service  Customer lines in service for business Telephone 
Exchange Service Customers in that LATA in the Commonwealth of Virginia that 
are not affiliates or employees of either BA or Focal, and (ii) residential 
Telephone Exchange Service shall be considered "fully operational" in a LATA 
in the Commonwealth of Virginia when Focal has an effective Tariff for 
residential Telephone Exchange Service in the Commonwealth of Virginia and 
has a significant number of Telephone Exchange Service Customer lines in service
for residential Telephone Exchange Service Customers in that LATA in the
Commonwealth of Virginia that are not affiliates or employees of either BA or 
Focal.

_____________________________
/1/     SS7 certification scheduling depends on actual schedule availability at
time of request.


                                       1


 

<PAGE>
 
SCHEDULE 4.0

VIRGINIA - INTERCONNECTION POINTS IN LATA



                                   LATA 236
                                   --------

F-IP:      Washington D.C. Switch
           1120 Vermont Ave. N.W.  
           Washington, D.C.
           WASHDCRKDS2

BA-IP      WorldCom COLO
           1025 N. Irving Street
           Arlington, VA
           ARTNVAARHVA



<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                          Dated as of October 2, 1998


                                by and between


                        BELL ATLANTIC - VIRGINIA, INC.

                                      and

                       FOCAL COMMUNICATIONS CORPORATION
                                  OF VIRGINIA
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996


     This Interconnection Agreement (this "Agreement"), under Sections 251 and
252 of the Telecommunications Act of 1996 (the "Act"), is effective as of the
2nd day of October, 1998 (the "Effective Date"), by and between Bell Atlantic -
Virginia, Inc. ("BA"), a Virginia corporation with offices at 600 East Main
Street, Richmond, Virginia 23219, and Focal Communications Corporation of 
Virigina ("Focal"), a Virginia corporation with offices at 200 N. LaSalle
Street, Suite 800, Chicago, Illinois 60601 (each a "Party" and, collectively,
the "Parties").

     WHEREAS, Focal has requested that BA make available to Focal
Interconnection, service and unbundled Network Elements upon the same terms and
conditions as provided in the Interconnection Agreement (and amendments thereto)
between MFS Intelenet of Virginia, Inc. and BA, dated as of July 16, 1996
(revised as of July 29, 1997), for Virginia, approved by the Commission under
Section 252 of the Act (the "Separate Agreement") and attached as Appendix 1
hereto; and

     WHEREAS, BA has undertaken to make such terms and conditions available to
Focal hereby only because and, to the extent required by, Section 252(i) of the
Act.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Focal and BA hereby agree as follows:

     1.0  INCORPORATION OF APPENDICES BY REFERENCE

     1.1  Except as expressly stated herein, the terms and conditions of the
Separate Agreement (as set forth in Appendix 1 hereto), as it is in effect on
the date hereof after giving effect to operation of law, and of the other
Appendices hereto are incorporated by reference in their entirety herein and
form an integral part of this Agreement.

     1.2  References in Appendix 1 hereto to MFS Intelenet of Virginia, Inc. or
to MFS shall for purposes of this Agreement be deemed to refer to Focal.

     1.3  References in Appendix 1 hereto to the "Effective Date", the date of
effectiveness thereof and like provisions shall for purposes of this Agreement
be deemed to refer to the date first written above. Unless terminated earlier in
accordance with the terms of Appendix 1 hereto, this Agreement shall continue in
effect until the Separate Agreement expires or is otherwise terminated.

     1.4  The Joint Grooming Plan referred to in Section 10.1 of Appendix 1 
hereto shall be developed upon the request of either Party within a reasonable 
amount of time after receipt of such request.
<PAGE>
 
     1.5  Notwithstanding Section 27.5 of Appendix 1 hereto, at such time as BA
makes available the Performance Monitoring Reports set forth in the Memorandum
Opinion and Order adopted by the FCC on August 14, 1997 (the "FCC Merger Order")
to other Telecommunications Carriers purchasing Interconnection from BA, BA
shall provide Focal with the Performance Monitoring Reports applicable to Focal
in accordance with the requirements of said FCC Merger Order.

     1.6  All notices, affidavits, exemption-certificates or other
communications to Focal under Section 29.6.6 of Appendix 1 hereto shall be sent
to the following address:

          Focal Communications Corporation of the Mid - Atlantic
          Attn:  Corporate Tax Department
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone:  (312) 895-8400

     1.7  All notices, affidavits, exemption-certificates or other
communications to BA under Section 29.6.6 of Appendix 1 hereto shall be sent to
the following address:

          Tax Administration
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          Room 3109
          New York, New York 10036

     1.8  Notices to Focal under Section 29.10 of Appendix 1 hereto shall be
sent to the following address:

          Focal Communications Corporation of the Mid - Atlantic
          Attn:  Senior Manager - Carrier Relations
          200 N. LaSalle Street, Suite 800
          Chicago, Illinois 60601
          Facsimile: (312) 895-8403
          Phone:  (312) 895-8400

     1.9  Notices to BA under Section 29.10 of Appendix 1 hereto shall be sent
to the following address:

          President - Telecom Industry Services
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          40/th/ Floor
          New York, New York 10036
          Facsimile: (212) 597-2585 

                                       2
<PAGE>
 
          with a copy to:

          Bell Atlantic Network Services, Inc.
          Attn: Mr. Jack H. White,
          Associate General Counsel
          1320 N. Court House Road, 8/th/ Floor
          Arlington, Virginia 22201
          Facsimile: (703) 974-O744

          with a copy to:

          Vice President and General Counsel
          Bell Atlantic - Virginia, Inc.
          600 East Main Street
          24th Floor
          Richmond, Virginia 23261
          Facsimile: (804) 772-2143

     1.10 Schedules 3.0 and 4.0 set forth at Appendix 2 hereto shall replace and
supersede in their entirety Schedules 3.0 and 4.0 of Appendix 1 hereto.

     2.0  CLARIFICATIONS

     2.1  The entry into, filing and performance by BA of this Agreement does
not in any way constitute a waiver by BA of any of the rights and remedies it
may have to seek review of any of the provisions of the Separate Agreement, or
to petition the Commission, other administrative body or court for
reconsideration or reversal of any determination made by any of them, or to seek
review in any way of any portion of this Agreement in connection with Focal's
election under Section 252(i) of the Act.





                          [Intentionally Left Blank]

                                       3
<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be 
executed as of this 2nd day of October, 1998.



FOCAL COMMUNICATIONS                  BELL ATLANTIC-
CORPORATION OF VIRGINIA               VIRGINIA, INC.


By:  /s/ John R. Barnicle             By: /s/ Jeffrey A. Masoner
    --------------------------            --------------------------------------

Printed: John R. Barnicle             Printed: Jeffrey A. Masoner
         ---------------------                 ---------------------------------

Title:   E.V.P. - C.O.O.              Title: Vice-President - Interconnection 
       -----------------------               -----------------------------------
                                             Services Policy & Planning
                                             --------------------------
      
                                       4
<PAGE>
 




                                   APPENDIX 1
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                           Dated as of July 16, 1996


                                by and between


                         BELL ATLANTIC-VIRGINIA, INC.

                                      and

                        MFS INTELENET OF VIRGINIA, INC.
<PAGE>
 

                               TABLE OF CONTENTS
                               -----------------
<TABLE> 
<CAPTION>                                                                   PAGE
                                                                            ----
<S>                                                                         <C> 
1.0   DEFINITIONS                                                             2

2.0   INTERPRETATION AND CONSTRUCTION                                        10 

3.0   INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION 
      SCHEDULE                                                               11 

4.0   INTERCONNECTION PURSUANT TO SECTION TO SECTION 251(c)(2)               11
4.1   Scope                                                                  12
4.2   Physical Architecture                                                  13 
4.3   Initial Architecture                                                   13
4.4   Interconnection in Additional LATAs                                    14
4.5   Interconnection Points for Different Types of Traffic                  15

5.0   TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE 
      TRAFFIC PURSUANT TO SECTION 251(c)(2)                                  15
5.1   Scope of Traffic                                                       15
5.2   Trunk Group Connections and Ordering                                   15
5.3   Additional Switching System Hierarchy and Trunking Requirements        15
5.4   Signaling                                                              16
5.5   Grades of Service                                                      16
5.6   Measurement and Billing                                                16
5.7   Reciprocal Compensation Arrangements -- Section 251(b)(5)              17

6.0   TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC 
      PURSUANT TO 251(c)(2)                                                  18
6.1   Scope of Traffic                                                       18
6.2   Trunk Group Architecture and Traffic Routing                           18
6.3   Meet-Point Billing Arrangements                                        19
6.4   800/888 Traffic                                                        21 

7.0   TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC                    22
7.1   Information Services Traffic                                           22
7.2   LSV/VCI Traffic                                                        23
7.3   Transit Service                                                        24
7.4   911/E911 Arrangements                                                  25
7.5   Ancillary Traffic Generally                                            26

8.0   NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS                      26 
</TABLE> 

                                       i
<PAGE>
 
9.0   NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES                        26

9.3   Interference or Impairment                                         28
9.4   Repeated or Willful Noncompliance                                  28
9.5   Outage Repair Standard                                             28
9.6   Notice of Changes -- Section 251(c)(5)                             28

10.0  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND
      INSTALLATION, MAINTENANCE, TESTING AND REPAIR                      28
10.1  Joint Network Reconfiguration and Grooming Plan                    28
10.2  Installation, Maintenance, Testing and Repair                      29
10.3  Forecasting Requirements for Trunk Provisioning                    29

11.0  UNBUNDLED ACCESS -- SECTION 251(c)(3)                              30
11.1  Unbundled Local Loop (ULL) Transmission Types                      30
11.2  Port Types                                                         31
11.3  Trunk Side Local Transport                                         32
11.4  Limitations on Unbundled Access                                    32
11.5  Availability of Other Network Elements on an Unbundled Basis       33
11.6  Provisioning of Unbundled Local Loops                              33
11.7  Maintenance of Unbundled Local Loops                               35
11.8  Rates and Charges                                                  35

12.0  RESALE -- SECTIONS 251(c)(4)and 251(b)(1)                          35
12.1  Availability of Retail Rates for Resale                            35
12.2  Availability of Wholesale Rates for Resale                         35

13.0  COLLOCATION -- SECTION 251(c)(6)                                   36

14.0  NUMBER PORTABILITY -- SECTION 251(b)(2)                            37
14.1  Scope                                                              37
14.2  Procedures for Providing INP Through Remote Call Forwarding        38     
14.3  Procedures for Providing INP Through Direct Inward Dial Trunks
      (Flex-DID)                                                         39
14.4  Procedures for Providing LTNP Through Full NXX Code Migration      39
14.5  Receipt of Terminating Compensation on Traffic to INP'ed Numbers   39
14.6  Recovery of INP Costs Pursuant to FCC Order and Rulemaking         40


15.0  DIALING PARITY -- SECTION 251(b)(3)                                41

16.0  ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                       41

17.0  DATABASES AND SIGNALING                                            41

                                     ii   
<PAGE>
 
18.0  COORDINATED SERVICE ARRANGEMENTS                                42
18.1  Intercept and Referral Announcements                            42
18.2  Coordinated Repair Calls                                        43
18.3  Customer Authorization                                          43
                                                              
19.0  DIRECTORY SERVICES ARRANGEMENTS                                 43
19.1  Directory Listings and Directory Distributions                  44
19.2  Yellow Page Maintenance                                         45
19.3  Service Information Pages                                       45
19.4  Directory Assistance (DA); Call Completion                      46
                                                              
20.0  COORDINATION WITH TARIFF TERMS                                  45
                                                              
21.0  INSURANCE                                                       46
                                                              
22.0  TERM AND TERMINATION                                            47
                                                              
23.0  DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                    48
                                                              
24.0  CANCELLATION CHARGES                                            48
                                                              
25.0  INDEMNIFICATION                                                 48
                                                              
26.0  LIMITATION OF LIABILITY                                         49
                                                              
27.0  PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                  50
27.1  Certain Definitions                                             50
27.2  Performance Standards                                           51
27.3  Limitations                                                     51
27.4  Service Quality Standards                                       52
27.5  Records                                                         52
                                                              
28.0  COMPLIANCE WITH LAWS; REGULATORY APPROVAL                       52
                                                              
29.0  MISCELLANEOUS                                                   53
29.1  Authorization                                                   53
29.2  Independent Contractor                                          53
29.3  Force Majeure                                                   53
29.4  Confidentiality                                                 54
29.5  Choice of Law                                                   55
29.6  Taxes                                                           55
29.7  Assignment                                                      57
29.8  Billing and Payment; Disputed Amounts                           57
29.9  Dispute Resolution                                              58
29.10 Notices                                                         59

                                      iii
<PAGE>
 



29.11 Section 252(i) Obligations                                       59
29.12 Joint Work Product                                               60
29.13 No Third Party Beneficiaries; Disclaimer of Agency               61 
29.14 No License                                                       61
29.15 Technology Upgrades                                              61
29.16 Survival                                                         62
29.17 Entire Agreement                                                 62 
29.18 Counterparts                                                     62
29.19 Modification, Amendment, Supplement or Waiver                    62
29.20 Successors and Assigns                                           62   
29.21 Publicity                                                        62

                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------ 
                 
Schedules
- ---------

Schedule 1.0        Certain Terms As Defined in the Act, As of July 16, 1996
Schedule 3.0        Implementation Schedule
Schedule 4.0        Interconnection Points in LATA
Schedule 4.2        Physical Architecture Diagram
Schedule 4.3        Initial Architecture Diagram
Schedule 4.5        Interconnection Points for Different Types of Traffic
Schedule 6.3        Rate Elements Under Meet Point Billing
Schedule 27.0       Performance Interval Dates for Specified Activities
Schedule 27.1       MFS Service Quality Standards

Exhibits      
- --------

Exhibit A           Detailed Schedule of Itemized Charges
Exhibit B           Network Element Bona Fide Request
Exhibit C           Directory Assistance and Call Completion Services Agreement


                                      iv
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996


     This Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996, is effective as of the 16th day of July, 1996
(the "Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched
Exchange Access Services, and other Telecommunications Services (all as defined
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will interconnect their networks and provide other services as
required by the Act (as defined below) and additional services as set forth
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996
have specific requirements for interconnection, unbundling, and service resale,
commonly referred to as the "Checklist", and the Parties intend that this
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA
and MFS (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements,
ancillary services, and wholesale Telecommunications Services available for
resale within each LATA in which they both operate within Virginia. As such,
this Agreement is an integrated package that reflects a balancing of interests
critical to the Parties. It will be submitted to the Virginia State Corporation
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of
the Agreement. So long as the Agreement remains in effect, neither Party shall
advocate before any legislative, regulatory, or other public forum that any term
of this Agreement be modified or eliminated, unless otherwise mutually agreed by
the Parties.

                                       1
<PAGE>
 
1.0  DEFINITIONS.

     As used in this Agreement, the following terms shall have the meanings
specified below in this Section 1.0. For convenience of reference only, the
definitions of certain terms that are As Defined in the Act (as defined below)
are set forth on Schedule 1.0.

     1.1  "Act" means the Communications Act of 1934 (47 U.S.C. 151 et. seq.) as
                                                                    --  ---
amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission.

     1.2  "ADSL" or "Asymmetrical Digital Subscriber Line" means a transmission
technology which transmits an asymmetrical digital signal of up to 6 mbps to the
Customer and up to 640 kbps from the Customer.

     1.3  [Reserved]

     1.4  "Agreement" means this Interconnection Agreement under Sections 251
and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5  "Ancillary Traffic," means all traffic that is destined for ancillary
services, or that may have special billing requirements, including but not
limited to the following: LSV/VCI, Directory Assistance, 911/E911, Operator
Services (call completion), 800/888 database query, LIDB, and information
services requiring special billing.

     1.6  "As Defined in the Act" means as specifically defined by the Act and
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     1.7  "As Described in the Act" means as described in or required by the Act
and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.8  "Automatic Number Identification" or "ANI" means a Feature Group D
signaling parameter which refers to the number transmitted through a network
identifying the billing number of the calling party.

     1.9  "Calling Party Number" or "CPN" is a Common Channel Signaling ("CCS")
parameter which refers to the number transmitted through a network identifying
the calling party.

     1.10 "Central Office Switch" means a switch used to provide
Telecommunications Services, including, but not limited to:

          (a) "End Office Switch" or "End Office" which is used to terminate
Customer station Loops for the purpose of interconnection to each other and to
trunks; and

                                       2
<PAGE>
 
          (b) "Tandem Switch" or "Tandem Office" which is a switching entity
that is used to connect and switch trunk circuits between and among End Office
Switches and between and among End Office Switches and carriers' aggregation
points, points of termination, or points of presence. An "Access Tandem Office"
or "Access Tandem" is a Tandem Office with billing and recording capabilities
that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End
Office/Tandem Office Switch.

     1.11 [Reserved]

     1.12 "CLASS Features" means certain CCS-based features available to
Customers including, but not limited to: Automatic Call Back; Call Trace; Caller
Identification, and future offerings.

     1.13 "Collocation" means an arrangement whereby one Party's (the
"Collocating Party") facilities are terminated in equipment necessary for
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a
second Party (the "Housing Party"). For purposes of Collocation, the "premises"
of a Housing Party is limited to a Housing Party Wire Center, other mutually
agreed-upon locations of the Housing Party, or any other location for which
Collocation has been ordered by the FCC or Commission. Collocation may be
"physical" or "virtual". In "Physical Collocation," the Collocating Party
installs and maintains its own equipment in the Housing Party's premises. In
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA
currently provides Collocation under terms, rates, and conditions as described
in tariffs on file or soon to be filed with the FCC and the Commission. Upon
request by either Party, BA and MFS will address the provision of additional
types of Collocation arrangements, including additional physical locations and
alternative utilizations of space and facilities.

     1.14 "Commission" means the Virginia State Corporation Commission.

     1.15 "Common Channel Signaling" or "CCS" means a method of transmitting
call set-up and network control data over a digital signaling network separate
from the public switched telephone network facilities that carry the actual
voice or data traffic of the call. "SS7" means the common channel out of band
signaling protocol developed by the Consultative Committee for International
Telephone and Telegraph ("CCITT") and the American National Standards Institute
("ANSI"). BA and MFS currently utilize this out-of-band signaling protocol.
"CCSAC" or "CCSAS" means the common channel signaling access connection or
service, respectively, which connects one Party's signaling point of
interconnection ("SPOI") to the other Party's STP for the exchange of SS7
messages.

                                       3
<PAGE>
 
     1.16  "Competing Local Exchange Carrier" or "CLEC" means any Local Exchange
Carrier other than BA, operating as such in BA's certificated territory in
Virginia. MFS is or will shortly become a CLEC.

     1.17  "Cross Connection" means a jumper cable or similar connection
provided pursuant to Collocation at the digital signal cross connect, Main
Distribution Frame or other suitable frame or panel between (i) the Collocating
Party's equipment and (ii) the equipment or facilities of the Housing Party.

     1.18  "Customer" means a third-party residence or business subscriber to
Telecommunications Services provided by either of the Parties.

     1.19  "Dialing Parity" is As Defined in the Act.

     1.20  "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.21  "Digital Signal Level 0" or "DS0" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.

     1.22  "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level
signal in the time-division multiplex hierarchy. In the time-division
multiplexing hierarchy of the telephone network, DS1 is the initial level of
multiplexing.

     1.23  "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level
in the time-division multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS3 is defined as the third level of
multiplexing.

     1.24  "Exchange Access" is As Defined in the Act.

     1.25. "Exchange Message Record" or "EMR" means the standard used for
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is
contained in BR-010-200-010 CRIS Exchange Message Record, a Bell Communications
Research, Inc. ("Bellcore") document that defines industry standards for
Exchange Message Records.

     1.26  [Reserved]

     1.27  "FCC" means the Federal Communications Commission.

     1.28  "HDSL" or "High-Bit Rate Digital Subscriber Line" means a
transmission technology which transmits up to 784 kbps simultaneously in both
directions on a two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line
code.

                                       4
<PAGE>
 
     1.29  "Independent Telephone Company" or "ITC" means any entity other than
BA which, with respect to its operations within Virginia, is an "Incumbent Local
Exchange Carrier" As Described in the Act.

     1.30  "Information Service Traffic" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which is
addressed to an information service provided over a Party's information services
platform.

     1.31  "Integrated Digital Loop Carrier" means a subscriber loop carrier
system which integrates within the switch at a DSI level that is twenty-four
(24) loop transmission paths combined into a 1.544 Mbps digital signal.

     1.32. "Integrated Services Digital Network" or "ISDN" means a switched
network service providing end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN") provides
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B+D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for
digital transmission of twenty three (23) 64 kbps bearer channels and one 16
kbps data and signaling channel (23 B+D).

     1.33  "Interconnection" is as Described in the Act, and means the
connection of separate pieces of equipment or transmission facilities within,
between, or among networks. The architecture of Interconnection may include, but
is not limited to, Collocation Arrangements, entrance facilities, and Mid-Span
Meet arrangements.

     1.34  "Interexchange Carrier" or "IXC" means a carrier that provides,
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35  "Interim Number Portability" or "INP" means the use of existing and
available call routing, forwarding, and addressing capabilities (e.g. remote
call forwarding) to enable a Customer to receive Telephone Exchange Service
provided by any Local Exchange Carrier operating within the exchange area with
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of
whether the Customer's chosen Local Exchange Carrier is the carrier that
originally assigned the number to the Customer.

     1.36  "InterLATA" is As Defined in the Act.

     1.37  "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.38  "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.

                                       5
<PAGE>
 
     1.39. "Line Status Verification" or "LSV" means an operator request for a
status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40  "Local Access and Transport Area" or "LATA" is As Defined in the Act.

     1.41  "Local Exchange Carrier" or "LEC" is As Defined in the Act. The
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42. "Local Serving Wire Center" means a Wire Center that (i) serves the
area in which the other Party's or a third party's Wire Center, aggregation
point, point of termination, or point of presence is located, or any Wire Center
in the LATA in which the other Party's Wire Center, aggregation point, point of
termination or point of presence is located in which the other Party has
established a Collocation Arrangement or is purchasing an entrance facility, and
(ii) has the necessary multiplexing capabilities for providing transport
services.

     1.43  "Local Telephone Number Portability" or "LTNP" means "number
portability" As Defined in the Act.

     1.44  "Local Traffic," means traffic that is originated by a Customer of
one Party on that Party's network and terminates to a Customer of the other
Party on that other Party's network, within a given local calling area, or
expanded area service ("EAS") area, as defined in BA's effective Customer
tariffs. Local Traffic does not include traffic originated or terminated by a
commercial mobile radio service carrier.

     1.45. "Main Distribution Frame" or "MDF" means the primary point at which
outside plant facilities terminate within a Wire Center, for interconnection to
other telecommunications facilities within the Wire Center.

     1.46. "MECAB" means the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
("OBF"), which functions under the auspices of the Carrier Liaison Committee
("CLC") of the Alliance for Telecommunications Industry Solutions ("ATIS"). The
MECAB document, published by Bellcore as Special Report SR-BDS-000983, contains
the recommended guidelines for the billing of an Exchange Access service
provided by two or more LECs, or by one LEC in two or more states, within a
single LATA.

     1.47  "MECOD" means the Multiple Exchange Carriers Ordering and Design
(MECOD) Guidelines for Access Services - Industry Support Interface, a document
developed by the Ordering/Provisioning Committee under the auspices of OBF. The
MECOD document, published by Bellcore as Special Report SR-STS-002643,
establishes methods for processing orders for Exchange Access service which is
to be provided by two or more LECs.

     1.48  "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched
Exchange Access Service to one

                                       6
<PAGE>
 
of the LECs' End Office Switches, with each LEC receiving an appropriate share
of the transport element revenues as defined by their effective Exchange Access
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an
effective Meet-Point Billing arrangement.

     1.49. "Mid-Span Meet" means an Interconnection architecture whereby two
carriers' fiber transmission facilities meet at a mutually agreed-upon
Interconnection point.

     1.50  "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff"
means the MPB method whereby each LEC prepares and renders its own meet point
bill in accordance with its own Tariff(s) for the portion of the jointly-
provided Switched Exchange Access Service which the LEC provides.

     1.51  "Network Element" is As Defined in the Act.

     1.52  "Network Element Bona Fide Request" means the process described on
Exhibit B that prescribes the terms and conditions relating to a Party's request
that the other Party provide a Network Element not otherwise provided by the
terms of this Agreement.

     1.53  "North American Numbering Plan" or "NANP" means the numbering plan
used in the United States that also serves Canada, Bermuda, Puerto Rico and
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 3-
digit NXX code and 4-digit line number.

     1.54. "Numbering Plan Area" or "NPA" is also sometimes referred to as an
area code. There are two general categories of NPAs, "Geographic NPAs" and "Non-
Geographic NPAs." A Geographic NPA is associated with a defined geographic
area, and all telephone numbers bearing such NPA are associated with services
provided within that geographic area. A Non-Geographic NPA, also known as a
"Service Access Code" or "SAC Code," is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55  "NXX," "NXX Code," or "End Office Code" means the three digit switch
entity indicator (i.e. the first three digits of a seven digit telephone
number).

     1.56  "Permanent Number Portability" or "PNP" means the use of a database
or other technical solution that comports with regulations issued by the FCC to
provide LTNP for all customers and service providers.

     1.57  "Port Element" or "Port" means a line card (or equivalent) and
associated peripheral equipment on an End Office Switch which serves as the
Interconnection between individual loops or individual Customer trunks and the
switching components of an End Office Switch and the associated switching
functionality in that End Office Switch. Each Port is typically associated with
one (or more) telephone number(s) which serves as the Customer's network 
address.

                                       7
<PAGE>
 
     1.58  "Rate Center Area" or "Exchange Area" means the specific geographic
point and corresponding geographic area which has been identified by a given LEC
as being associated with a particular NPA-NXX code assigned to the LEC for its
provision of Telephone Exchange Services. The Rate Center Area is the exclusive
geographic area which the LEC has identified as the area within which it will
provide Telephone Exchange Services bearing the particular NPA-NXX designation
associated with the specific Rate Center Area. A "Rate Center Point" is a
specific geographic point, defined by a V&H coordinate, located within the Rate
Center Area and used to measure distance for the purpose of billing Customers
for distance-sensitive Telephone Exchange Services and Toll Traffic.

     1.59  "Rate Demarcation Point" means the point of minimum penetration at
the Customer's premises or other point, as defined in a Party's Tariffs, where
network access recurring charges and LEC responsibility ends and beyond which
Customer responsibility begins.

     1.60  "Rating Point" or "Routing Point" means a specific geographic point
identified by a specific V&H coordinate. The Rating Point is used to route
inbound traffic to specified NPA-NXXs and to calculate mileage measurements for
distance-sensitive transport charges of switched access services. Pursuant to
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office
location, or a "LEC Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point/Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point corresponding to each unique and separate Rate Center.

     1.61  "Reciprocal Compensation" is As Described in the Act, and refers to
the payment arrangements that recover costs incurred for the transport and
termination of Local Traffic originating on one Party's network and terminating
on the other Party's network.

     1.62  "Service Control Point" or "SCP" means the node in the common channel
signaling network to which informational requests for service handling, such as
routing, are directed and processed. The SCP is a real time database system
that, based on a query from a service switching point and via a Signaling
Transfer Point, performs subscriber or application-specific service logic, and
then sends instructions back to the SSP on how to continue call processing.

     1.63  "Signaling Transfer Point" or "STP" means a specialized switch that
provides SS7 network access and performs SS7 message routing and screening.

     1.64  "Switched Access Detail Usage Data" means a category 1101XX record
as defined in the EMR Bellcore Practice BR-010-200-010.

     1.65  "Switched Access Summary Usage Data" means a category 1150XX record
as defined in the EMR Bellcore Practice BR-0l0-200-0l0.

                                       8
<PAGE>
 
     1.66  "Switched Exchange Access Service" means the offering of transmission
and switching services for the purpose of the origination or termination of Toll
Traffic. Switched Exchange Access Services include but may not be limited to:
Feature Group A, Feature Group B, Feature Group D, 700 access, 800 access, 888
access, and 900 access.

     1.67  "Synchronous Optical Network" or "SONET" means an optical interface
standard that allows inter-networking of transmission products from multiple
vendors. The base rate is 51.84 Mbps (OC-l/STS-l) and higher rates are direct
multiples of the base rate, up to 13.22 Gpbs.

     1.68  "Tariff" means any applicable federal or state tariff of a Party, or
standard agreement or other document that sets forth the generally available
terms and conditions under which a Party offers a particular service, facility,
or arrangement.

     1.69  "Technically Feasible Point" is As Described in the Act.

     1.70  "Telecommunications" is As Defined in the Act.

     1.71  "Telecommunications Act" means the Telecommunications Act of 1996 and
any rules and regulations promulgated thereunder.

     1.72  "Telecommunications Carrier" is As Defined in the Act.

     1.73  "Telecommunications Service" is As Defined in the Act.

     1.74  "Telephone Exchange Service," sometimes also referred to as "Exchange
Service," is As Defined in the Act. Telephone Exchange Service generally
provides the Customer with a telephonic connection to, and a unique telephone
number address on, the public switched telecommunications network, and enables
such Customer to place or receive calls to all other stations on the public
switched telecommunications network.

     1.75. "Toll Traffic" means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that Party's network and is not Local Traffic or Ancillary Traffic. Toll Traffic
may be either "IntraLATA Toll Traffic" or "InterLATA Toll Traffic," depending on
whether the originating and terminating points are within the same LATA.

     1.76  "Transit Traffic" means any traffic that originates from or
terminates at MFS's network, "transits" BA's network substantially unchanged,
and terminates to or originates from a third carrier's network, as the case may
be. "Transit Traffic Service" provides MFS with the ability to use its
connection to a BA Access Tandem Switch for the delivery of calls which
originate or terminate with MFS and terminate to or originate from a carrier
other than BA, such as another CLEC, a LEC other than BA, or a wireless carrier.
In these cases, neither the originating nor terminating Customer is a Customer
of BA. This service is provided through BA's Access Tandem

                                       9
<PAGE>
 
Switches. "Transit Traffic" and "Transit Traffic Service" do not include or
apply to traffic that is subject to an effective Meet-Point Billing arrangement.

     1.77  "Trunk Side" means a Central Office Switch connection that is capable
of, and has been programmed to treat the circuit as, connecting to another
switching entity (e.g. another carrier's network). Trunk Side connections offer
those transmission and signaling features appropriate for the connection of
switching entities.

     1.78  "Unbundled Local Loop Element" or "ULL" means a transmission path
that extends from a Main Distribution Frame, DSX-panel, or functionally
comparable piece of equipment in the Customer's serving End Office to the Rate
Demarcation Point (or network interface device (NID) if installed) in or at a
Customer's premises. The actual loop transmission facilities used to provide an
ULL may utilize any of several technologies.

     1.79  "Verification with Call Interruption" or "VCI" means a service that
may be requested and provided when Line Status Verification has determined that
a line is busy due to an ongoing call. VCI is an operator interruption of that
ongoing call to inform the called party that a calling party is seeking to
complete his or her call to the called party.

     1.80  "Voice Grade" means either an analog signal of 300 to 3000 Hz or a
digital signal of 56/64 kilobits per second. When referring to digital voice
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.81  "Wire Center" means a building or portion thereof in which a Party
has the exclusive right of occupancy and which serves as a Routing Point for
Switched Exchange Access Service.

2.0  INTERPRETATION AND CONSTRUCTION.

     2.1   All references to Sections, Exhibits and Schedules shall be deemed to
be references to Sections of, and Exhibits and Schedules to, this Agreement
unless the context shall otherwise require. The headings used in this Agreement
are inserted for convenience of reference only and are not intended to be a part
of or to affect the meaning of this Agreement. Unless the context shall
otherwise require, any reference to any agreement, other instrument (including
BA or other third party offerings, guides or practices), statute, regulation,
rule or tariff is to such agreement, instrument, statute, regulation, or rule or
tariff as amended and supplemented from time to time (and, in the case of a
statute, regulation, rule or tariff, to any successor provision).

     2.2   Subject to the terms set forth in Section 20, each Party hereby
incorporates by reference those provisions of its tariffs that govern the
provision of any of the services or facilities provided hereunder. If any
provision of this Agreement and an applicable tariff cannot be reasonably
construed or interpreted to avoid conflict, the Parties agree to negotiate in
good faith to reconcile and resolve such conflict. If any provision contained in
this main body of the Agreement and any Exhibit hereto cannot be reasonably
construed or interpreted to avoid conflict, the

                                      10
<PAGE>
 
provision contained in this main body of the Agreement shall prevail. The fact
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for
finding, a conflict for purposes of this Section 2.


3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1  Subject to the terms and conditions of this Agreement, each Party
shall exercise its best efforts to adhere to the Interconnection Activation
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to
provide fully operational service predominantly over its own Telephone Exchange
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes
of this Agreement, MFS's service in Virginia shall be considered provided
"predominantly over its own Telephone Exchange Service facilities" if MFS uses
its own Central Office Switch(es) (as opposed to resale of another carrier's
Telephone Exchange Service or Ports) to serve the majority of its Telephone
Exchange Service Customers, its own interoffice transport facilities for the
majority of its interoffice transport needs, and its own local loops (or
functional equivalent), in addition to resale of other carriers' Telephone
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2  Schedule 3.0 may be revised and supplemented from time to time upon
the mutual agreement of the Parties to reflect the intention of the Parties to
interconnect in additional LATAs pursuant to subsection 4.4 by attaching one or
more supplementary schedules to Schedule 3.0. The Parties stipulate and agree
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act, and the requirements of
the Competitive Checklist, under Section 271 of the Act. MFS represents that it
is, or intends to become, a provider of Telephone Exchange Service to
residential and business subscribers offered exclusively over its own Telephone
Exchange Service facilities or predominantly over its own Telephone Exchange
Service facilities in combination with the resale of the Telecommunications
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit
Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to the terms
and conditions of this Agreement, Interconnection of the Parties facilities and
equipment for the transmission and routing of Local Traffic and Toll Traffic
pursuant to this Section 4 shall be established on or before the corresponding
"Interconnection Activation Date" shown for each such LATA within Virginia on
Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and supplemented
from time to time upon the mutual agreement of the Parties to reflect
Interconnection in additional LATAs

                                      11
<PAGE>
 
in Virginia pursuant to subsection 4.4 by attaching one or more supplementary   
addenda to such Schedules.
 
     4.1  SCOPE

          4.1.1  Section 4 describes the architecture for Interconnection of the
Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct trunk groups:

          Traffic Exchange Trunks for the transmission and routing of
          -----------------------
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251 (c)(2) of the Act, in accordance with Section 5 below;

          Access Toll Connecting Trunks for the transmission and routing of
          -----------------------------                                    
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Access Service via
          a BA Access Tandem, pursuant to Section 251 (c)(2) of the Act, in
          accordance with Section 6 below;

          Information Services Trunks for the transmission and routing of
          ---------------------------                                    
          terminating Information Services Traffic in accordance with Section 7
          below;

          LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
          --------------                                                        
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating E911/
          ---------------
          911 traffic, in accordance with Section 7 below;

          Directory Assistance Trunks for the transmission and routing of
          ---------------------------                                    
          terminating directory assistance traffic, in accordance with
          subsection 19.4 below; and

          Operator services (call completion) Trunks for the transmission and
          ------------------------------------------                         
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2  The SONET interconnection arrangement described in subsection
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA
Toll Traffic until such time as the Parties have agreed to appropriate
compensation arrangements relating to the exchange of other types of traffic
over such system, and (ii) subject to the Parties' reaching agreement on an
appropriate compensation arrangement in the event either Party will be providing
or utilizing (in terms of minutes of use) significantly more than one-half of
the SONET facility. Unless otherwise agreed to by the Parties, the SONET system
described herein shall not be used to exchange InterLATA Toll Traffic. Until the
SONET system has been established by the Parties in accordance with subsection
4.3 and this subsection 4.1.2, the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
(IntraLATA and InterLATA) Traffic.

                                      12
<PAGE>
 
          4.1.3  To the extent required by Section 251 of the Act, the Parties
represent that the arrangements provided in subsections 4.2 and 4.3 of this
Agreement provide for Interconnection to each other's networks at any
technically feasible point. For the purposes of this Agreement, the Parties
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a Local
Serving Wire Center and/or other points as specified herein, and, in the case of
MFS, at a node or Central Office and/or other points as specified herein
(collectively, the "Interconnection Points" or "IPs").

          4.1.4  The Parties shall establish physical interconnection points at
the available IPs at the locations designated in Schedule 4.0. The mutually
agreed-upon IPs on the MFS network at which MFS will provide transport and
termination of traffic shall be designated as the MFS Interconnection Points
("M-IPs"); the mutually agreed-upon IPs on the BA network shall be designated as
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of
charging for the transport of traffic from the BA-IP to the M-IP in any given
LATA, the M-IP shall be no further than an entrance facility away from the BA-IP
in such LATA. The Parties may by mutual agreement establish additional
interconnection points at any technically feasible points consistent with the
Act.

     4.2  PHYSICAL ARCHITECTURE. In each LATA identified on Schedule 4.0, MFS
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous
Optical Network ("SONET") transmission system by which they shall interconnect
their networks pursuant to the joint network reconfiguration and grooming plan
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the
following specifications:

          4.2.1  The SONET system shall be used to deliver appropriate traffic
to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2  The SONET transmission system in each LATA shall be configured
substantially as illustrated in Schedule 4.2 and pursuant to the Joint Grooming
Plan, or as otherwise mutually agreed. The Parties shall agree upon which Party
or Parties shall be responsible for procuring, installing, and maintaining the
agreed-upon Optical Line Terminating Multiplexor ("OLTM") equipment, fiber optic
facilities and other equipment pursuant to the Joint Grooming Plan, as
illustrated in that Schedule.

          4.2.3  The physical interface of MFS's and BA's facilities necessary
to effect SONET transmission shall be at the optical level via a Mid-Span Meet
or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1  The Parties agree to provide initial interconnection
arrangements utilizing electrical handoffs, substantially as illustrated in
Schedule 4.3, for a period of no more than

                                      13
<PAGE>
 
eighteen (18) months after the later of the Effective Date and the LATA Start
Date set forth for the LATA in Schedule 3.0; provided, however, that such
initial interconnection arrangements shall continue until (i) facilities
suitable for the SONET arrangements described in subsection 4.2 are established
by each of the Parties in its own sole discretion in the LATA at the mutually
agreed-upon SONET meet points and made available, and (ii) the Parties have
agreed upon fully compatible OLTM equipment for use with such facilities.

          4.3.2  The Parties agree to utilize the M-IP and BA-IP in each LATA as
designated in Schedule 4.0 as the points from which each Party will provide the
transport and termination of traffic.

          4.3.3  MFS shall provide its own facilities for the delivery of
traffic to a collocation arrangement established at the BA-IP pursuant to
Section 13. Bell Atlantic shall provide transport and termination of the traffic
beyond the BA-IP.

          4.3.4  BA shall purchase an MFS entrance facility (and any necessary
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the 
M-IP. Alternatively, BA may choose to provide its own facilities to a
collocation arrangement established at the M-IP pursuant to Section 13. MFS
shall provide transport and termination of the traffic beyond the M-IP.

          4.3.5  Under this initial architecture described in this subsection
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5
below and pursuant to the other Party's Switched Exchange Access Service
tariffs. The other Party's Switched Exchange Access Service rates shall apply to
such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.

     4.4  INTERCONNECTION IN ADDITIONAL LATAS

          4.4.1  If MFS determines to offer Telephone Exchange Services in any
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange
Services, MFS shall provide written notice to BA of the need to establish
Interconnection in such LATA pursuant to this Agreement.

          4.4.2  The notice provided in subsection 4.4.1 shall include (i) the
initial Routing Point MFS has designated in the new LATA; (ii) MFS's requested
Interconnection Activation Date (and related milestone dates in accordance with
the format in Schedule 3.0); and (iii) a non-binding forecast of MFS's trunking
requirements.

          4.4.3  Unless otherwise agreed to by the Parties, the Parties shall
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local
Serving Wire Center that houses an Access Tandem Office within the LATA nearest
to the M-IP (as measured in airline miles

                                      14
<PAGE>
 
utilizing the V&H coordinates method) as the BA-IP in that LATA, provided that,
for the purpose of charging for the transport of traffic from the BA-IP to the 
M-IP, the M-IP shall be no further than an entrance facility away from the 
BA-IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to
reflect the schedule applicable to each new LATA requested by MFS; provided,
however, that unless agreed by the Parties, the Interconnection Activation Date
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten
(10) business days of BA's receipt of MFS's notice, BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party
shall make available Interconnection Points and facilities for routing of
traffic from those Interconnection Points as designated in Schedule 4.5. Any
additional traffic that is not covered in Schedule 4.5 shall be subject to
separate negotiations between the Parties, except that (i) either Party may
deliver traffic of any type or character to the other Party for termination as
long as the delivering Party pays the receiving Party's then current Switched
Exchange Access rates for such traffic, and (ii) upon a bona fide request from
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an
agreement covering the exchange of such traffic.

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO
SECTION 251(c)(2)

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups
(the "Traffic Exchange Trunks") to be effected over the Interconnections
specified in Section 4.0 for the transmission and routing of Local Traffic and
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-l level or higher
for exchange of Local and Toll Traffic. Higher speed connections shall be made,
when and where available, in accordance with the Joint Grooming Plan prescribed
in Section 10. Ancillary Traffic trunk groups may be made below a DS-l level, as
may be agreed to by the Parties.

          5.2.2  Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

       5.3.1  For purposes of routing MFS traffic to BA, the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own or

                                      15
<PAGE>
 
other carriers' traffic. For purposes of routing BA traffic to MFS, the
subtending arrangements between MFS Access Tandem Switches (or functional
equivalent) and MFS End Office Switches (or functional equivalent) shall be the
same as the Access Tandem/End Office subtending arrangements (or functional
equivalent) which MFS maintains for the routing of its own or other carriers'
traffic.

     5.4     SIGNALING

     Each Party will provide the other Party with access to its databases and
associated signaling necessary for the routing and completion of the other
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5     GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6     MEASUREMENT AND BILLING

         5.6.1   For billing purposes, each Party shall pass Calling Party
Number ("CPN") information on each call carried over the Traffic Exchange
Trunks, wherever technically feasible. At such time as either Party has the
ability, as the Party receiving the traffic, to use such CPN information to
classify on an automated basis traffic delivered by the other Party as either
Local Traffic or Toll Traffic, such receiving Party shall bill the originating
Party the Local Traffic termination rates, Intrastate Exchange Access rates, or
Interstate Exchange Access rates applicable to each minute of Traffic for which
CPN is passed, as provided in Exhibit A and applicable Tariffs.

         5.6.2   If, under the circumstances set forth in subsection 5.6.1. it
is not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party the
Local Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, for which CPN is passed. For the remaining up
to ten percent (10%) of calls without CPN information, the receiving Party shall
bill the originating Party for such traffic as Local Traffic termination rates,
Intrastate Exchange Access rates, or Interstate Exchange Access rates applicable
to each minute of traffic, as provided in Exhibit A and applicable Tariffs, in
direct proportion to the minutes of use of calls passed with CPN information.

         5.6.3   If it is not technically feasible for the originating Party to
pass CPN on more than ten percent (10%) of calls, or if the receiving Party
lacks the ability to use CPN information to classify on an automated basis
traffic delivered by the other Party as either Local Traffic or Toll Traffic,
and the originating Party chooses to combine Local and Toll Traffic on the same
trunk group, it will supply an auditable Percent Local Use ("PLU") report
quarterly, based on the previous three months' traffic, and applicable to the
following three months. If the originating

                                      16
<PAGE>
 
Party also chooses to combine Interstate and Intrastate Toll Traffic on the same
trunk group, it will supply an auditable Percent Interstate Use ("PIU") report
quarterly, based on the previous three months' terminating traffic, and
applicable to the following three months. In lieu of the foregoing PLU and/or
PIU reports, the Parties may agree to provide and accept reasonable surrogate
measures for an agreed-upon interim period.

         5.6.4   Measurement of billing minutes for purposes of determining
terminating compensation shall be in conversation seconds.

     5.7     RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

     Reciprocal Compensation arrangements address the transport and termination
of Local Traffic. BA's delivery of Traffic to MFS that originated with a third
carrier is addressed in subsection 7.3. Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and termination of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

         5.7.1   Nothing in this Agreement shall be construed to limit either
Party's ability to designate the areas within which that Party's Customers may
make calls which that Party rates as "local" in its Customer Tariffs.

         5.7.2   The Parties shall compensate each other for transport and
termination of Local Traffic in an equal and symmetrical manner at the rates
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if
not set forth therein, in the applicable Tariff(s) of the terminating Party, as
the case may be. These rates are to be applied at the M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges,
including port or transport charges, shall apply for the termination of Local
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A.
When Local Traffic is terminated over the same trunks as Toll Traffic, any port
or transport or other applicable access charges related to the Toll Traffic
shall be prorated to be applied only to the Toll Traffic.

         5.7.3   The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs.

         5.7.4   Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5. 

                                      17
<PAGE>
 
         5.7.5   The designation of Traffic as Local or Toll for purposes of
compensation shall be based on the actual originating and terminating points of
the complete end-to-end call, regardless of the carrier(s) involved in carrying
any segment of the call.

         5.7.6   Each Party reserves the right to measure and audit all Traffic
to ensure that proper rates are being applied appropriately. Each Party agrees
to provide the necessary Traffic data or permit the other Party's recording
equipment to be installed for sampling purposes in conjunction with any such
audit.

         5.7.7   The Parties will engage in settlements of alternate-billed
calls (e.g. collect, calling card, and third-party billed calls) originated or
       - -
authorized by their respective Customers in Virginia in accordance with the
terms of an appropriate billing services agreement for intraLATA intrastate
alternate-billed calls or such other arrangement as may be agreed to by the
Parties.


6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2).

     6.1     SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over
the Interconnections specified in Section 4 for the transmission and routing of
traffic between MFS Telephone Exchange Service Customers and Interexchange
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2     TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

         6.2.1   MFS shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from MFS's Customers.

         6.2.2   Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access to allow MFS's Customers to connect
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

         6.2.3   The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch MFS utilizes to provide Telephone Exchange
Service and Switched Exchange Access in a given LATA to an Access Tandem BA
utilizes to provide Exchange Access in such LATA.

         6.2.4   The Parties shall jointly determine which BA Access Tandem(s)
will be subtended by each MFS End Office Switch. MFS's End Office switch shall
subtend the BA Access Tandem that would have served the same rate center on BA's
network. Alternative configurations will be discussed as part of the Joint Plan.

                                      18
<PAGE>
 
     6.3     MEET-POINT BILLING ARRANGEMENTS

             6.3.1  MFS and BA will establish Meet-Point Billing arrangements
in order to provide a common transport option to Switched Access Services
Customers via an Access Tandem Switch in accordance with the Meet-Point Billing
guidelines contained in the OBF's MECAB and MECOD documents, except as modified
herein, and BA's Virginia Tariff Number 217, Section 2.4.8. The arrangements
described in this Section 6 are intended to be used to provide Switched Exchange
Access Service that originates and/or terminates on a Telephone Exchange Service
that is provided by either Party, where the transport component of the Switched
Exchange Access Service is routed through a Tandem Switch that is provided by
BA.

             6.3.2  In each LATA, the Parties shall establish MPB arrangements
between the applicable Rating Point/BA Local Serving Wire Center combinations.

             6.3.3  Interconnection for the MPB arrangement shall occur at the
BA-IP in the LATA, unless otherwise agreed to by the Parties.

             6.3.4. MFS and BA will use reasonable efforts, individually and
collectively, to maintain provisions in their respective state access tariffs,
and/or provisions within the National Exchange Carrier Association ("NECA")
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

             6.3.5  Each Party shall implement the "Multiple Bill/Single Tariff"
or "Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an
IXC for the portion of the jointly provided telecommunications service provided
by that Party.

             6.3.6  The rate elements to be billed by each Party are as set
forth in Schedule 6.3. The actual rate values for each Party's affected access
service rate element shall be the rates contained in that Party's own effective
federal and state access tariffs, or other document that contains the terms
under which that Party's access services are offered. The MPB billing
percentages for each Rating Point/BA Local Serving Wire Center combination shall
be calculated in accordance with the formula set forth in subsection 6.3.16
below.

             6.3.7  Each Party shall provide the other Party with the billing
name, billing address, and Carrier Identification Code ("CIC") of the IXC, and
identification of the IXC's Local Serving Wire Center in order to comply with
the MPB notification process as outlined in the MECAB document via facsimile
or such other media as the Parties may agree to.

             6.3.8  BA shall provide MFS with the Switched Access Detail Usage
Data (category 1101XX records) on magnetic tape or via such other media as the
Parties may agree to, no later than ten (10) business days after the date the
usage occurred.

             6.3.9  MFS shall provide BA with the Switched Access Summary Usage
Data (category 115OXX records) on magnetic tape or via such other media as the
Parties may agree, no

                                      19
<PAGE>
 
later than ten (10) business days after the date of its rendering of the bill to
the relevant IXC, which bill shall be rendered no less frequently than monthly.

             6.3.10  Each Party shall coordinate and exchange the billing
account reference ("BAR") and billing account cross reference ("BACR") numbers
or Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each
Party shall notify the other if the level of billing or other BAR/BACR elements
change, resulting in a new BAR/BACR number, or if the OCN changes.

             6.3.11. Errors may be discovered by MFS, the IXC or BA. Each Party
agrees to provide the other Party with notification of any errors it discovers
within two (2) business days of the date of such discovery. In the event of a
loss of data, both Parties shall cooperate to reconstruct the lost data and, if
such reconstruction is not possible, shall accept a reasonable estimate of the
lost data based upon prior usage data.

             6.3.12  Either Party may request a review or audit of the various
components of access recording up to a maximum of two (2) audits per calendar
year. All costs associated with each review and audit shall be borne by the
requesting Party. Such review or audit shall be conducted subject to
confidentiality protection and during regular business hours. A Party may
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

             6.3.13. Nothing contained in this subsection 6.3. shall create any
liability for damages, losses, claims, costs, injuries, expenses or other
liabilities whatsoever on the part of either Party (other than as may be set
forth in MECAB or in any applicable Tariff).

             6.3.14. The Parties shall not charge one another for the services
rendered or information provided pursuant to this subsection 6.3.

             6.3.15  MPB will apply for all traffic bearing the 500, 900,
800/888 (to the extent provided by an IXC) or any other non-geographic NPA which
may be likewise designated for such traffic in the future.

             6.3.16  In the event MFS determines to offer Telephone Exchange
Services in another LATA in which BA operates an Access Tandem Switch, BA shall
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for
the BA End Offices in the area where the MFS Rating Point(s) associated with the
NPA-NXX(s) to/from which the Switched Exchange Access Services are homed. The
MPB billing percentages for each new Rating Point/BA Local Serving Wire Center
combination shall be calculated according to the following formula:

                      a / (a + b) = MFS Billing Percentage
                                      and
                      b / (a + b) = BA Billing Percentage

               where:
               ------

                                      20
<PAGE>
 
               a = the airline mileage between the Rating Point and the actual
          point of interconnection for the MPB arrangement; and

               b = the airline mileage between the BA Local Serving Wire Center
          and the actual point of interconnection for the MPB arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange
Services and its calculation of the billing percentages which should apply for
such arrangement, as part of the notice required by subsection 4.4.1 above.
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS
shall confirm the new Rating Point/BA Local Serving Wire Center combination and
billing percentages. Nothing in this subsection 6.3.16 shall be construed to
limit MFS's ability to select to interconnect with BA in additional LATAs by
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

    6.4  800/888 TRAFFIC

    The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

         6.4.1.  When MFS delivers untranslated 800/888 calls to BA for
completion

                 (a)  to an IXC, BA shall:

                      (i)    Provide a MPB record in an industry standard format
                      to MFS; and

                      (ii)   Bill the IXC the appropriate BA query charge
                      associated with the call.

                 (b)  as an IntraLATA call to BA or another LEC in the LATA, BA
shall

                      (i)    Provide a copy record in an industry standard
                      format to MFS;

                      (ii)   Bill MFS the appropriate BA query charge associated
                      with the call; and

                      (iii)  Submit the call records to ITORP for payment by BA
                      or the LEC that is the 800/888 service provider of MFS's
                      and any intermediate LEC's Tariffed Exchange Access
                      charges and query charges.

                                      21
<PAGE>
 
          6.4.2   When BA delivers 800/888 calls originated by BA's or another
LEC's Customers to MFS for completion

                  (a)   to MFS in its capacity as an IXC, BA shall:

                        (i)    Bill MFS the appropriate BA query charge
                        associated with the call; and

                        (ii)   Bill MFS the appropriate FGD Exchange Access
                        charges associated with the call.

                  (b)   as an IntraLATA call to MFS in its capacity as a LEC,

                        (i)    BA shall submit the appropriate call records to
                        ITORP for payment by MFS of BA's (and another LEC's, if
                        appropriate) Tariffed Exchange Access charges; and

                        (ii)   MFS shall pay the originating LEC's appropriate
                        query charge associated with the call.


7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to MFS-originated Information
Services Traffic directed to an information services platform connected to BA's
network. At such time as MFS connects Information Services platforms to its
network, the Parties shall agree upon a suitable arrangement for BA-originated
Information Services Traffic.

          7.1.1  MFS shall route Information Services Traffic that originates on
its own network to the appropriate information services platform(s) connected to
BA's network. MFS will establish a dedicated trunk group to the BA information
services serving switch. This trunk group will be utilized to allow MFS to
route information service traffic originated on its network to BA.

          7.1.2  MFS shall provide an electronic file transfer or monthly
magnetic tape containing recorded call detail information to BA.

          7.1.3  BA shall provide to MFS via electronic file transfer or
magnetic tape or other means as available all necessary information to rate the
Information Services Traffic to MFS's Customers pursuant to the BA's agreements
with each information services provider. Information shall be provided in as
timely a fashion as practical in order to facilitate record review and reflect
actual prices set by the individual information services providers.

                                      22
<PAGE>
 
          7.1.4  MFS shall bill and collect such information services provider
charges and remit the amounts collected to BA less:

          (a)  The Information Services Billing and Collection fee set forth in
     Exhibit A; and

          (b)  An uncollectibles reserve calculated based on the uncollectibles
     reserve in BA's billing and collection agreement with the applicable
     information services provider; and

          (c)  Customer adjustments provided by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and
Customer adjustments to allow BA to pass through the adjustments to the
information services provider, and BA shall pass through such adjustments.
However, if the information services provider disputes such adjustments and
refuses to accept such adjustments, MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputed adjustments shall be solely
between MFS and the information services provider.

          7.1.5  Nothing in this Agreement shall restrict either Party from
offering to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

          7.1.6  The Parties may agree to separate arrangements for the billing
and compensation of variable rated (e.g. 970, 540) information services.
                                    - -

          7.1.7  The Information Services Traffic addressed herein does not
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1  Each Party shall offer LSV and VCI services to enable its
Customers to verify and/or interrupt calls of the other Party's Customers. In
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party
(Party A) and the responding Party (Party B) shall perform in accordance with
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to
be agreed upon between the Parties.

          7.2.2  The Party B operator shall only verify the status of the line
(LSV) or interrupt the line to inform the called party that there is a call
waiting. The Party B operator will not complete the telephone call of the
Customer initiating the LSV/VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable
charges apply whether or not the called party releases the line.

                                      23
<PAGE>
 
          7.2.3  Each Party's operator bureau shall accept LSV and VCI inquiries
from the operator bureau of the other Party in order to allow transparent
provision of LSV/VCI Traffic between the Parties' networks.

          7.2.4  Each Party shall route LSV/VCI Traffic inquiries over separate
direct trunks (and not the Local/IntraLATA/InterLATA Trunks) established between
the Parties' respective operator bureaus. Each Party shall offer interconnection
for LSV/VCI traffic at its Local Serving Wire Center, operator services Tandem
Office subtended by such Local Serving Wire Center, or other mutually agreed
point in the LATA. Separate LSV/VCI trunks delivered at the Local Serving Wire
Center will be directed to the operator services Tandem Office designated by
Party B. Unless otherwise mutually agreed, the Parties shall configure LSV/VCI
trunks over the Interconnection architectures in accordance with the terms of
Section 4, consistent with the Joint Grooming Plan. Party A shall outpulse the
appropriate NPA, ATC Code, and Routing Code (operator code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a
reciprocal local traffic exchange arrangement (either via written agreement or
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as
quickly as commercially reasonable following the Effective Date and to provide
copies thereof to BA, but continues to utilize BA's Transit Service for the
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC,
MFS shall, in addition to paying the rate set forth in Exhibit A for said
Transit Service, pay BA any charges or costs such terminating third party
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred by
                                       ----
BA in delivering or terminating such Traffic and/or resulting from MFS's failure
to secure said reciprocal local traffic exchange arrangement. BA will, upon
request, provide MFS with all reasonable cooperation and assistance in obtaining
such arrangements. The Parties agree to work cooperatively in appropriate
industry fora to promote the adoption of reasonable industry guidelines relating
to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will
deliver each call to each involved network with CCS and the appropriate
Transactional Capabilities Application Part ("TCAP") message to facilitate full
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and
exchange records between the Parties and with the terminating carrier to
facilitate the billing process to the originating network.

                                      24
<PAGE>
 
          7.3.4  Transit Traffic shall be routed over the Traffic Exchange
Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

          7.4.1  MFS will interconnect to the BA 911/E911 selective routers or
911 Tandem Offices, where available, which serve the areas in which MFS provides
Telephone Exchange Services, for the provision of 911/E911 services and for
access to all subtending Public Safety Answering Points ("PSAP"). In such
situations, BA will provide MFS with the appropriate CLLI codes and
specifications of the Tandem Office serving area. In areas where E911 is not
available, MFS and BA will negotiate arrangements to connect MFS to the 911
service.

          7.4.2  Path and route diverse interconnections for 91l/E911 shall be
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed,
and as required by law or regulation.

          7.4.3  Upon request, BA will provide MFS with the following:

          (a)    an electronic interface, when available, through which MFS
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911
     information such as name, address, and telephone number in writing for BA's
     entry into the 911 database system. Any 911-related data exchanged between
     the Parties shall conform to the National Emergency Number Association
     standards;

          (b)    a file containing the Master Street Address Guide ("MSAG"), as
     may be updated from time to time, for the exchanges or communities
     specified;

          (c)    a return of any MFS E911 data entry files containing errors, so
     that MFS may ensure the accuracy of the Customer records; and

          (d)    PSAP 911 Tandem information.

          7.4.4  In cases where a Customer of one Party elects to discontinue
its service and become the Customer of the other Party ("Party B") but desires
to retain its original telephone number pursuant to an INP or PNP arrangement,
Party B will outpulse the telephone number to which the call has been forwarded
(i.e. the Customer's ANI) to the 911 Tandem Office. Party B will also provide
 - -
the 911 database with both the forwarded number and the directory number, as
well as the appropriate address information of the Customer.

          7.4.5  BA and MFS will use their best efforts to facilitate the
prompt, robust, reliable and efficient interconnection of MFS systems to the 
911/E911 platforms.

                                      25
<PAGE>
 
          7.4.6  BA and MFS will work cooperatively to arrange meetings with 
PSAPs to answer any technical questions the PSAPs, or county or municipal
coordinators may have regarding the 911/E911 arrangements. BA shall assist MFS
in identifying the appropriate person in each municipality for the purpose of
obtaining the ten-digit subscriber number of each PSAP.

          7.4.7  The Parties acknowledge that the provision of INP, until PNP
with full 911 compatability is available, creates a special need to have the
Automatic Location Identification ("ALI") screen reflect two number: the "old"
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification
("TCI") of the company that provides service to the calling line as part of the
ALI display. Until such time as TCI is operational, however, BA and MFS agree to
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8  MFS will compensate BA for connections to its 911/E911
pursuant to Exhibit A.

          7.4.9  MFS will comply with all applicable rules and regulations
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY  Ancillary Traffic that may be terminated
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise
adversely affect in any manner either Party's right to employ or to request and
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code
Assignment Guidelines, as may be amended from time to time, or to establish, by
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX
codes. Until such time as number administration is provided by a third party, BA
shall provide MFS access to telephone numbers by assigning NXX codes to MFS in
accordance with such Assignment Guidelines.

     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing
Guide ("LERG") in order to recognize and route traffic to the other Party's
assigned NXX codes at all times. Neither Party shall impose any fees or charges
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, MFS shall
adopt the Rate Center Areas and Rate Center Points that the Commission has
approved for BA, in all areas where BA and

                                      26
<PAGE>
 
MFS service areas overlap, and MFS shall assign whole NPA-NXX codes to each
Rate Center unless the LEC industry adopts alternative methods of utilizing NXXs
in the manner adopted by the NANP.

     8.4  MFS will also designate a Routing Point for each assigned NXX code.
MFS shall designate one location for each Rate Center Area as the Routing Point
for the NPA-NXXs associated with that Area, and such Routing Point shall be
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in
this Agreement is intended to, and nothing in this Agreement shall be construed
to, in any way constrain MFS's choices regarding the size of the local
calling area(s) that MFS may establish for its Customers, which local calling
areas may be larger than, smaller than, or identical to, BA's local calling
areas.


9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance
                                                           - -
contact numbers, network information, information required to comply with law
enforcement and other security agencies of the Government) to achieve this
desired reliability. In addition, the Parties will work cooperatively to apply
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that
may be agreed to between the Parties and to employ characteristics and methods
of operation that will not interfere with or impair the service or any
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of
operation used by Party B will or may interfere with or impair its provision of
services, Party A shall have the right to discontinue Interconnection subject,
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days' prior written
notice of interference or impairment or potential interference or impairment
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice
provided to Party B under (a) above to the appropriate federal and/or state
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall
not be required in emergencies and Party A may immediately discontinue
Interconnection if reasonably necessary

                                      27
<PAGE>
 
to meet its obligations. In such case, however, Party A shall use all reasonable
means to notify Party B and the appropriate federal and/or state regulatory
bodies.

          9.3.4     Upon correction of the interference or impairment, Party A 
will promptly renew the Interconnection. During such period of discontinuance, 
there will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

          9.4.1     The Interconnection provided hereunder may be discontinued 
by either Party upon thirty (30) days written notice to the other for repeated 
or willful violation of and/or a refusal to comply with this Agreement. The 
Party discontinuing will notify the appropriate federal and/or state regulatory 
bodies concurrently with the notice to the other Party of the prospective 
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or 
service being provided by a Party hereunder, the providing Party will follow 
procedures for isolating and clearing the outage or trouble that are no less 
favorable than those that apply to comparable arrangements, facilities, or 
services being provided by the providing Party to any other carrier whose 
network is connected to that of the providing Party. MFS and BA may agree to 
modify those procedures from time to time based on their experience with 
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES -- SECTION 251(C)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN. On or before December
1, 1996, unless the Parties agree to a different date, MFS and BA shall jointly 
develop a grooming plan (the "Joint Plan") which shall define and detail, inter 
                                                                          ----- 
alia,
- ----

          (a)  modifications to the agreement on physical architecture 
     consistent with the guidelines defined in Section 4;

          (b)  standards to ensure that Interconnection trunk groups experience
     a grade of service, availability and quality which is comparable to that
     achieved on interoffice trunks within BA's network and in accord with all
     appropriate relevant industry-accepted

                                      28

<PAGE>
 
     quality, reliability and availability standards. Trunks provided by either 
     Party for Interconnection services will be engineered using a design 
     blocking objective of B.01;

          (c)  the respective duties and responsibilities of the Parties with
     respect to the administration and maintenance of the trunk groups,
     including, but not limited to, standards and procedures for notification
     and discoveries of trunk disconnects;

          (d)  disaster recovery provision escalations;

          (e)  migration from one-way to two-way Interconnection Trunks upon 
     mutual agreement of the Parties;

          (f)  actual meet point locations on the SONET system; and

          (g)  such other matters as the Parties may agree.

     10.2 INSTALLATION, MAINTENANCE, TESTING AND REPAIR.  BA's standard 
intervals for Feature Group D Switched Exchange Access Services will be used for
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of its facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its 
inability to do so and will negotiate such intervals in good faith. The Parties 
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than 
those applicable to comparable arrangements, facilities, or services being 
provided by such Party to any other carrier whose network is connected to that 
of the providing Party.

     10.3 FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING.  Within sixty (60)
days of executing this Agreement, MFS shall provide BA a one (1) year traffic
forecast. This initial forecast will provide the amount of traffic to be
delivered to each of BA's End Offices affected by the exchange of traffic. The
forecast shall be updated and provided to BA on a quarterly basis, and include
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator
services, 911, etc.), code (identifies trunk group), A location/Z location (CLLI
codes), interface type (e.g., DS1), and trunks in service each year
(cumulative).

          10.3.1 Initial Forecast/Trunking Requirements. Because BA's trunking 
                 --------------------------------------
requirements will, at least during an initial period, be dependent on the 
customer segments and service segments within customer segments to whom MFS 
decides to market its services, BA will be largely dependent on MFS to provide 
accurate trunk forecasts for both inbound (from BA) and outbound (from MFS) 
traffic. BA will, as an initial matter and upon request, provide the same 
number of trunks to terminate local traffic to MFS as MFS provides to terminate 
local traffic to BA, unless MFS expressly identifies particular situations that 
are expected to produce traffic that is substantially skewed in either the 
inbound or outbound direction, in which case BA will provide the number of 
trunks MFS suggests. Upon the establishment of any new set of trunks for traffic
from BA to MFS, BA will monitor traffic for ninety (90) days, and will, as

                                      29

<PAGE>
 
necessary at the end of that period, either augment trunks or disconnect 
trunks, based on the application of reasonable engineering criteria to the 
actual traffic volume experienced. If, after such 90-day period, BA has 
determined that the trunks are not warranted by actual traffic volumes, then, on
ten (10) days' written notice, BA may hold MFS financially responsible for such 
trunks retroactive to the start of the 90-day period until such time as they are
justified by actual traffic volumes, based on the application of reasonable 
engineering criteria. To the extent that BA requires MFS to install trunks for 
delivery of traffic to BA, MFS may apply the same procedures with respect to 
BA's trucking requirements.

11.0 UNBUNDLED ACCESS - SECTION 251(C)(3).

     To the extent required of each Party by Section 251 of the Act, each Party
shall offer to the other Party nondiscriminatory access to Network Elements on
an unbundled basis at any technically feasible point. BA shall unbundle and
separately price and offer Network Elements such that MFS will be able to lease
and interconnect to whichever of the Network Elements MFS requires, and to
combine the BA-provided elements with any facilities and services that MFS may
itself provide, except that MFS shall not recombine Network Elements purchased
from BA for use as a substitute for the purchase at wholesale rates of
Telecommunications Services that BA provides unless otherwise mandated by the
FCC or the Commission or agreed to by BA with other carriers.

     11.1 UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

     Subject to subsection 11.4, BA shall allow MFS to access the following ULL
types (in addition to those ULLs available under applicable tariffs) unbundled
from local switching and local transport in accordance with the terms and
conditions set forth in this subsection 11.1.

          11.1.1 "2-Wire Analog Voice Grade ULL" or "Analog 2W" provides an
effective 2-wire channel with 2-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals and loop-
start signaling. The service is more fully described in Bell Atlantic TR-72565.
If "Customer-Specified Signaling" is requested, the service will operate with
one of the following signaling types that may be specified when the service is
ordered: loop-start, ground-start, loop-reverse-battery, and no signaling. The
service is more fully described in Bell Atlantic TR-72570.

          11.1.2 "4-Wire Analog Voice Grade ULL" or "Analog 4W" provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The
service will operate with one of the following signaling types that may be
specified when the service is ordered: loop-start, ground-start, loop-reverse-
battery, duplex, and no signaling. The service is more fully described in Bell
Atlantic TR-72570.

          11.1.3 "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides a 
channel with 2-wire interfaces at each end that is suitable for the transport of
160 kbps digital services using the ISDN 2B1Q line code.

                                      30

<PAGE>
 
          11.1.4 "2-Wire ADSL-Compatible ULL" or "ADSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of digital
signals up to 6Mbps toward the Customer and up to 640 kbps from the Customer. BA
will offer ADSL-Compatible ULLs only when the technology BA uses to provide such
ULLs is compatible with that of MFS. In addition, ADSL-Compatible ULLs will be
available only where existing copper facilities can meet applicable industry
standards.

          11.1.5 "2-Wire HDSL-Compatible ULL" or "HDSL 2W" provides a channel 
with 2-wire interfaces at each end that is suitable for the transport of 784 
kbps digital signals simultaneously in both directions using the 2B1Q line code.
HDSL compatible ULLs will be available only where existing copper facilities can
meet the specifications.

          11.1.6 "4-Wire HDSL-Compatible ULL" or "HDSL 4 W" provides a channel 
with 4-wire interfaces at each end. Each 2-wire channel is suitable for the 
transport of 784 kbps digital signals simultaneously in both directions using 
the 2B1Q line code. HDSL compatible ULLs will be available only where existing 
copper facilities can meet specfications.

          11.1.7 ULLs will be offered on the terms and conditions specified 
herein and on such other terms in applicable Tariffs that are not inconsistent 
with the terms and conditions set forth herein. BA shall make ULLs available to 
MFS at the rates specified by the Commission, as amended from time to time, 
subject to the provisions of subsection 11.1.8 below.

          11.1.8 BA will make Analog 2-Wire ULLs available for lease by MFS in 
accordance with the schedule set forth in Schedule 3.0. BA will make BRI ISDN 
and Analog 4W ULLs available for lease by MFS by the later of January 1, 1997, 
or the date when the ULL milestone contained in Schedule 3.0 is achieved in the 
LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease by MFS
as soon as practicable, but in any event no later than six months, after BA 
makes the services using equivalent loop facilities commercially available to 
its own end-user Customers in Virginia. Upon request by either BA or MFS, the 
Parties shall agree upon a reasonable schedule and location for a technical and 
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s) 
may, by mutual agreement, be conducted in any jurisdiction in which affiliates 
of BA and MFS both operate. Upon successful completion of such trial(s), the 
Parties shall agree upon an implementation schedule for the ULL type(s) subject 
to such trial(s), which schedule shall begin no later than ninety (90) days
after successful completion of such trial(s).

     11.2 PORT TYPES

     BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.
                                            ---- ----

                                      31

<PAGE>
 
     11.3  TRUNK SIDE LOCAL TRANSPORT

     BA shall provide MFS local transport from the trunk side of BA's Central 
Office Switches using private lines and special access services unbundled from 
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

     11.4  LIMITATIONS ON UNBUNDLED ACCESS

           11.4.1 Unless otherwise mandated by the FCC or the Commission or 
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under 
applicable tariffs.

           11.4.2 BA shall not be required to make available ULLs and Ports 
where such ULLs and Ports are available.

           11.4.3 MFS shall access BA's unbundled Network Elements specifically 
identified in this Agreement via Collocation in accordance with Section 13 at 
the BA Wire Center where those elements exist and each ULL or Port shall be 
delivered to MFS's Collocation by means of a Cross Connection.

           11.4.4 BA shall provide MFS access to its Unbundled Local Loops at
each of BA's Wire Centers for loops terminating in that Wire Center. In
addition, if MFS requests one or more ULLs provisioned via Integrated Digital
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA
shall, where available, move the requested ULL(s) to a spare, existing physical
ULL at no additional charge to MFS.  If, however, no spare physical ULL is
available, BA shall within three (3) business days of MFS's request notify MFS
of the lack of available facilities. MFS may then at its discretion make a
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the
ULL concentration site point. Alternatively, MFS may choose to avail itself of
BA's Special Construction services, as set forth in Exhibit A, for the
provisioning of such ULL(s). Notwithstanding anything to the contrary in this
Agreement, the provisioning intervals set forth in subsection 11.6 and the
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this
subsection 11.4.4.

           11.4.5 If MFS orders a ULL type and the distance requested on such 
ULL exceeds the transmission characteristics in applicable technical references,
distance extensions may be required and additional rates and charges shall 
apply as set forth in Exhibit A or applicable Tariffs.

           11.4.6 BA will exercise all reasonable efforts to ensure that the 
service intervals that apply to ULLs and unbundled Ports are comparable to the 
(i) repair intervals that apply to the bundled dial tone line service, and (ii) 
installation intervals that apply to other BA-coordinated services, except as 
provided in Section 27. Although BA will make commercially

                                      32

 





<PAGE>
 
reasonable efforts to ensure that ULLs and unbundled ports meet specified or 
agreed-upon technical standards, BA makes no warranty that the ULLs or unbundled
Ports supplied by BA hereunder will be compatible with the services MFS may 
offer to its Customers if they are used in a manner not contemplated by the 
Parties.

     11.5  AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

           11.5.1 BA shall, upon request of MFS, and to the extent technically 
feasible, provide to MFS access to its Network Elements on an unbundled basis 
for the provision of MFS's Telecommunications Service. Any request by MFS for 
access to an BA Network Element that is not already available shall be treated 
as a Network Element Bona Fide Request. MFS shall provide BA access to its 
Network Elements as mutually agreed by the Parties or as required by the 
Commission or FCC.

           11.5.2 A Network Element obtained by one Party from the other Party 
under this subsection 11.5 may be used in combination with the facilities of the
requesting Party only to provide a Telecommunications Service, including
obtaining billing and collection, transmission, and routing of the
Telecommunications Service.

           11.5.3 Notwithstanding anything to the contrary in this subsection 
11.5, a Party shall not be required to provide a proprietary Network Element to
the other Party under this subsection 11.5 except as required by the Commission 
or FCC.

     11.6  PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs. These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA 
to MFS and from MFS to BA.

           11.6.1 Upon request by MFS, BA will apply the following coordination 
procedures to conversions of live Telephone Exchange Services to ULLs. 
Coordinated cutover charges will apply to any such arrangement, only to the 
extent provided by Section A.4.a of Exhibit A. If MFS elects not to request 
coordinated cutover, BA will process MFS's request in the normal course and 
subject to the normal installation intervals.

           11.6.2 MFS shall request ULLs from BA by delivering to BA a valid 
electronic transmittal service order (when available) or another mutually 
agreed-upon type of service order. Such service order shall be provided in 
accordance with industry format and specifications or such format and 
specifications as may be agreed to by the Parties. Within forty-eight (48) hours
of BA's receipt of such valid service order, BA shall provide MFS the firm order
commitment date according to the Performance Interval Dates set forth in 
Schedule 27 by which the ULLs covered by such service order will be installed. 
In addition, BA shall provide MFS with the relating ULL design information, if 
available, at least forty eight (48) hours prior to the scheduled cutover time.

                                      33
<PAGE>
 
          11.6.3    On each ULL order in a Wire Center, MFS and BA will agree on
a cutover time at least forty eight (48) hours before that cutover time. The 
cutover time will be defined as a 15-30 minute window within which both the MFS 
and BA personnel will make telephone contact to complete the cutover.

          11.6.4    Within the appointed 15-30 minute cutover time, the MFS 
person will call the BA organization designated to coordinate cross-connection
work and when the BA organization is reached in that interval such work will be
promptly performed.

          11.6.5    If MFS requires a change in scheduling, it must contact BA 
to issue a supplement to the original order. The negotiations process to 
determine the date and time of cutover will then be reinitiated as usual.

          11.6.6    If MFS person is not ready within the appointed interval and
if MFS had not called to reschedule the work at least two (2) hours prior to the
start of the interval, MFS shall be liable for the non-recurring charge for the 
unbundled elements scheduled for the missed appointment. In addition, 
non-recurring charges for the rescheduled appointment will apply.

          11.6.7    If BA is not available or not ready at any time during the 
appointed 15-30 minute interval, MFS and BA will reschedule and BA will waive 
the non-recurring charge for the unbundled elements originally scheduled for 
that interval, whenever those unbundled elements are actually cutover pursuant 
to an agreed-upon rescheduling.

          11.6.8    The standard time expected from disconnection of a live 
Telephone Exchange Service to the connection of the unbundled element to the MFS
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all 
orders consisting of fifteen (15) ULLs or less. Orders involving more than 
fifteen (15) ULLs will require a negotiated interval.

          11.6.9    If unusual or unexpected circumstances prolong or extend the
time required to accomplish the coordinated cutover, the Party responsible for 
such circumstances is responsible for the reasonable labor charges of the other 
Party. Delays caused by the Customer are the responsibility of MFS.

          11.6.10   If MFS has ordered INP as part of an ULL installation, BA 
will coordinate implementation of INP with the ULL installation. BA's provision 
of unbundled elements shall in all cases be subject to the availability of 
suitable facilities, to the extent permitted by Section 251 of the Act.

          11.6.11   If MFS requests or approves a BA technician to perform 
services on the network side of the Rate Demarcation Point beyond normal 
installation of the ULLs covered by the service order, BA may charge MFS for any
additional and reasonable labor charges to perform such services. BA may also 
charge MFS its normal overtime rates for services MFS requests to be performed 
outside of BA's normal business hours (M-F, 9 am to 5 pm, E.S.T.).

                                      34
<PAGE>
 
     11.7 MAINTENANCE OF UNBUNDLED LOCAL LOOPS

     If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a dispatch,
(iii) BA dispatches a technician, and (iv) such trouble was not caused by BA's
facilities or equipment, then MFS shall pay BA a per-trip charge charge and
labor charges per quarter hour increments for time associated with said
dispatch, as set forth in Exhibit A. In addition this charge also applies in
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA with appropriate dispatch information based on their test results.
If, as the result of MFS instructions, BA is erroneously requested to dispatch
within the Central Office, BA may levy on MFS an appropriate charge.

     11.8 RATES AND CHARGES

     BA shall charge the non-recurring and monthly recurring rates for unbundled
Local Loops and other Network Elements set forth in Exhibit A.


12.0 RESALE -- SECTIONS 251(C)(4) AND 251(B)(1).

     12.1 AVAILABILITY OF RETAIL RATES FOR RESALE

     Each Party shall make available its Telecommunications Services for resale
at retail rates to the other Party in accordance with Section 251(b)(1) of the
Act.

     12.2 AVAILABILITY OF WHOLESALE RATES FOR RESALE

     BA shall make available to MFS for resale at wholesale rates set forth in 
Exhibit A all Telecommunications Services that BA provides at retail to 
Customers that are not Telecommunications Carriers. Such services shall be 
provided in accordance with the terms of the applicable retail services 
Tariff(s), including, without limitation, user or user group restrictions, as 
the case may be, subject to the requirement that such restrictions shall in all 
cases comply with the requirements of Section 251 of the Act regarding 
restrictions on resale. In addition, BA and MFS shall each allow the resale by 
the other of all Telecommunications Services that are offered primarily or 
entirely to other Telecommunications Carriers (e.g., Switched and special 
Exchange Access Services) at the rates already applicable to such services. BA
shall also allow the resale by MFS of such other non-Telecommunications Services
as BA, in its sole discretion, determines to provide for resale under terms and
conditions to be agreed to by the Parties. If MFS requests resale at wholesale
rates of Telecommunications Services that BA provides at retail to Customers
that are not Telecommunications Carriers before April 1, 1997, the Parties shall
negotiate and agree upon the terms and conditions for ordering, provisioning,
billing, and maintaining such resale arrangements before MFS submits any orders
for such resale, which terms and conditions are unlikely to rely on automated
interfaces. During the period before April 1, 1997, the Parties shall negotiate
and agree upon, in the form of a separate agreement to be appended hereto,
resale arrangements to apply after that date. Such arrangements shall, to the
extent feasible and

                                      35

<PAGE>
 
economically reasonable, employ automated interfaces for ordering, provisioning,
billing, and maintaining resold accounts. The Parties may also agree to 
negotiate term and/or volume discounts for resold services.


13.0 COLLOCATION - SECTION 251(c)(6).

     13.1 BA shall offer to MFS Physical Collocation of equipment necessary for 
Interconnection (pursuant to Section 4) or for access to unbundled Network 
Elements (pursuant to Section 11.0), except that BA may offer only Virtual 
Collocation if BA demonstrates to the Commission that Physical Collocation is 
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for 
the purpose of Interconnection with facilities or services of BA or access to 
unbundled Network Elements of BA, except as otherwise mutually agreed to in 
writing by the Parties or as required by the FCC or the Commission, subject to 
applicable federal and state Tariffs.

     13.2 Although not required to do so by Section 251(c)(6) of the Act, by 
this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either 
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to 
Section 4) on a non-discriminatory basis and at comparable rates, terms and
conditions as MFS may provide to other third parties. MFS shall provide such
Collocation subject to applicable Tariffs.

     13.3 Where MFS is Virtually Collocated on the date hereof on a premise that
was initially prepared for Physical Collocation for MFS, MFS may elect to (i) 
retain its Virtual Collocation in that premises, and/or (ii) establish Physical 
Collocation in that premises pursuant to current procedures and applicable 
Tariffs. BA will not assess to MFS non-recurring charges for central office 
common area construction to transition existing virtual collocation arrangements
to physical collocation arrangements in offices where MFS previously paid such 
charges. BA will also waive cage construction charges for cages of the same size
originally paid for by MFS. MFS shall coordinate with BA for rearrangement of 
MFS's equipment, facilities, and circuits. All applicable Physical Collocation 
recurring charges shall apply.

     13.4 Where MFS is Virtually Collocated on the date hereof on a premise that
was initially prepared for MFS as Virtual Collocation, MFS may elect to (i) 
retain its Virtual Collocation in that premises, or (ii) unless it is not 
practical for technical reasons or because of space limitations, convert its 
Virtual Collocation at such premises to Physical Collocation, in which case MFS 
shall coordinate the construction and rearrangement with BA of its equipment, 
facilities, and circuits, and for which MFS shall pay BA at applicable Tariff
rates. In addition, all Physical Collocation recurring charges shall apply.

     13.5 For both Physical Collocation and Virtual Collocation, the Collocating
Party shall provide its own or third-party leased transport facilities and 
terminate those transport facilities in equipment located in its Physical 
Collocation space, or in its virtually collocated equipment, at the Housing 
Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

                                      36
<PAGE>
 
     13.6  Collocation shall occur under the terms of each Party's applicable
and available Tariffs. Collocation is offered for network Interconnection
between the Parties. Unless otherwise agreed to by the Parties or either Party
is required by applicable law to permit on its collocated premises, neither
Party shall use a Collocation Arrangement to directly interconnect with a third
party's equipment or facilities collocated at the same location.


                           SECTION 251(b) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2).

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability
("LTNP") on a reciprocal basis to each other to the extent technically feasible,
and in accordance with rules and regulations as from time to time prescribed by
the FCC and/or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the
industry pursuant to regulations issued by the FCC and/or the Commission, the
Parties agree to reciprocally provide Interim Number Portability to each other
at the prices listed in Exhibit A. Such agreed-upon prices for INP are not
intended to reflect either Party's views on the cost recovery mechanisms being
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable
FCC and/or Commission order(s) or regulations mandating the adoption of a
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as
practically possible while minimizing interruption or degredation of service to
their respective Customers. Once PNP is implemented, either Party may withdraw,
at any time and at its sole discretion, its INP offerings, subject to advance
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant
to FCC or Commission regulation, both Parties agree to conform and provide such
PNP. To the extent PNP rates or cost recovery mechanisms are not established by
the applicable FCC or Commission order or regulation mandating the adoption of
PNP, the Parties will negotiate in good faith the charges or cost recovery
mechanism for PNP service at such time as a PNP arrangement is adopted by the
Parties.

          14.1.4  Under either an INP or PNP arrangement, MFS and BA will
implement a process to coordinate LTNP cutovers with ULL conversions (as
described in Section 11 of this Agreement).

                                      37
<PAGE>
 
     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1  A Customer of one Party ("Party A") elects to become a
Customer of the other Party ("Party B"). The Customer elects to utilize the
original telephone number(s) corresponding to the Telephone Exchange Service(s)
it previously received from Party A, in conjunction with the Telephone Exchange
Service(s) it will now receive from Party B. Upon receipt of a service order
from Party B requesting assignment of the number(s) to Party B, Party A will
implement an arrangement whereby all calls to the original telephone number(s)
will be forwarded to a new telephone number(s) designated by Party B, only
within the same Exchange Area as the original telephone number(s). Party A will
route the forwarded traffic to Party B over the appropriate traffic exchange
trunk groups.

          14.2.2  Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties, Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3  Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated 
with those forwarded numbers as directed by Party B. In addition, Party A will 
update the retained numbers in the LIDB with the screening options provided by 
Party B on a per order basis. Party B shall determine which of the screening 
options offered by Party A should apply to the Party B Customer account.

          14.2.4  Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          14.2.5  Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a 
third party that is authorized to act on behalf of the Customer. Party A shall 
provide notification to Party B of third party orders affecting the INP service 
of a Party B customer. The Parties agree to work cooperatively to develop 
procedures or adopt industry standards or practices concerning the initiation 
and termination of INP service in a multi-carrier environment.

          14.2.6  The INP service offered herein shall not initially apply to 
NXX Codes 555, 915, 976, or 950, or for Feature Group A or coin telephone 
service. Upon request of either Party, provision of INP to these services will 
be mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any
arrangement that would render the forwarded call Toll Traffic.

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<PAGE>
 
          14.2.7  The ordering of INP arrangements and the exchange of screening
information shall be made in accordance with industry-accepted (e.g. OBF
developed) format and specifications to the extent they have been implemented by
the Parties.

     14.3  PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS
(FLEXDID) Either Party may also request INP through Direct Inward Dial Trunks
pursuant to any applicable Tariffs.

     14.4  PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION Where
either Party has activated an entire NXX for a single Customer, or activated a
substantial portion of an NXX for a single Customer, with the remaining numbers
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other
Party, the first Party shall cooperate with the second Party to have the entire
NXX reassigned in the LERG (and associated industry databases, routing tables,
etc.) to an End Office operated by the second Party. Such transfer will be
accomplished with appropriate coordination between the Parties and subject to
appropriate industry lead-times for movements of NXXs from one switch to
another. Neither Party shall charge the other in connection with this
coordinated transfer.

     14.5  RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed
numbers should be received by each Customer's chosen LEC as if each call to the
Customer had been originally addressed by the caller to a telephone number
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to
accomplish this objective where INP is employed, the Parties shall utilize the
process set forth in this subsection 14.5 whereby terminating compensation on
calls subject to INP will be passed from the Party (the "Performing Party")
which performs the INP to the other Party (the "Receiving Party") for whose
Customer the INP is provided.

          14.5.1  The Parties shall individually and collectively make best
efforts to track and quantify INP traffic between their networks based on the
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving
Party shall charge the Performing Party for each minute of INP traffic at the
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other
compensation charges for terminating such traffic, except as provided in
subsection 14.5.2.

          14.5.2  By the Interconnection Activation Date in each LATA, the
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as
Transit Traffic. On the date which is six (6) months after the Interconnection
Activation Date, and thereafter on each succeeding six month anniversary of such
Interconnection Activation Date, the Parties shall establish new INP traffic
percentages to be applied in the prospectives six (6) month period based

                                      39
<PAGE>
 
on the Performing Party's choice of actual INP traffic percentages from the
preceding six (6) month period or historic data of all traffic in the LATA.

          14.5.3  The INP Traffic Rate shall be equal to the sum of:

   (Recip Traffic percentage times the Reciprocal Compensation Rate set forth in
                             -----
                                   Exhibit A)
                                      plus
                                      ----

   (Intra Traffic percentage times Receiving Party's effective intrastate FGD 
                             -----
                                     rates)                                     
                                      plus
                                      ----

   (Inter Traffic percentage times Receiving Party's effective interstate FGD
                             -----
                                    rates).

     The Receiving Party shall compensate the Performing Party for its billing
and collection of charges for the intrastate and interstate FGD access services
provided by the Receiving Party to a third party through the greater of (i) the
difference between the intrastate and interstate FGD rates of the Receiving
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     14.6  RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this section 14, in
light of the FCC's First Report and Order and Further Notice of Proposed
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the
Parties stipulate and agree as follows:

          14.6.1  The rates listed in Exhibit A for the provision of INP are
appropriate amounts that each Party providing INP service should recover for the
provision of those INP functionalities in BA's operating territory. For the INP
functions it provides, each Party should be allowed to recover these amounts in
a manner consistent with any final FCC and/or Commission order on INP cost
recovery (such as a state-wide fund contributed to by all telecommunications
carriers).

          14.6.2  Within three (3) weeks of the Effective Date, the Parties will
jointly seek a Commission proceeding and ruling to develop and implement an INP
cost recovery mechanism consistent with the policy described in the Order and/or
any subsequent FCC or Commission decision.

          14.6.3  Until such time as a final FCC and/or Commission order,
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the other Party at the INP rates listed in Exhibit A. All revenues
received by the providing Party from its provision of INP service to the other
Party shall be placed into an escrow fund maintained by or tracked separately by
the providing Party. Upon issuance of a final FCC and/or Commission order, and
to the extent that it permits the Party providing INP to recover the associated
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal

                                      40
<PAGE>
 
to the amount it recovers from such fund for its provision of INP service to the
purchasing Party from the Effective Date, provided that in no event shall the
refund amount exceed the aggregate amount the providing Party has received from
the purchasing Party for INP services. If no such fund is ordered or
established, the providing Party shall retain the full amount of the revenues
tracked or held in escrow by it pursuant to this subsection 14.6.3.

          14.6.4 The Parties agree that neither Party waives its rights to 
advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.

15.0 DIALING PARITY -- SECTION 251(B)(3).

     BA and MFS shall each provide the other with nondiscriminatory access to 
such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4).

     Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C. (S)
224, as set forth in Exhibit A, where facilities are available, on terms,
conditions and prices comparable to those offered to any other entity pursuant
to each Party's applicable Tariffs. Where no such Tariffs exist, such access
shall be provided in accordance with the requirements of 47 U.S.C. (S) 224,
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C. (S) 224
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the
appropriateness of applying such changes on a retroactive basis to the date
hereof. If the Parties are unable to agree on the necessary changes to the
existing arrangements or the appropriateness of applying them on a retroactive
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.

17.0 DATABASES AND SIGNALING.

     17.1 Each Party shall provide the other Party with access to databases and
associated signaling necessary for call routing and completion by providing SS7
Common Channel Signaling (CCS) Interconnection in accordance with existing
Tariffs, and Interconnection and access 800/888 databases, LIDB, and any other
necessary databases in accordance with existing Tariffs and/or agreements with
other unaffiliated carriers, as set forth in the Exhibit A. Alternatively,
either Party may secure CCS Interconnection from a commercial

                                      41

<PAGE>
 
SS7 hub provider, and in that case the other Party will permit the purchasing 
Party to access the same databases as would have been accessible if the 
purchasing party had connected directly to the other Party's CCS network.

     17.2 The Parties will provide CCS Signaling to one another, where and as 
available, in conjunction with all Local Traffic, Toll Traffic, Meet Point 
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between 
their respective networks, including all CLASS features and functions, to the 
extent each Party offers such features and functions to its Customers. All CCS 
Signaling parameters will be provided upon request (where available), including 
called party number, calling party number, originating line information, calling
party category, and charge number. All privacy indicators will be honored. The 
Parties will follow all Ordering and Billing Forum-adopted standards pertaining 
to CIC/OZZ codes. Where CCS Signaling is not available, in-band multi-frequency 
(MF) wink start signaling will be provided. Any such MF arrangement will require
a separate local trunk circuit between the Parties' respective switches. In such
an arrangement, each Party will outpulse the full ten-digit telephone number of 
the called party to the other Party.

     17.3 Each Party shall provide trunk groups, where available and upon 
reasonable request, that are configured utilizing the B8ZS ESF protocol for 64 
kbps clear channel transmission to allow for ISDN interoperability between the 
Parties' respective networks.

     17.4 The following publications describe the practices, procedures and 
specifications generally utilized by BA for signaling purposes and is listed 
herein to assist the Parties in meeting their respective Interconnection 
responsibilities related to Signaling:

          (a)  Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC 
Networks - Signaling; and 

          (b)  Bell Atlantic Supplement Common Channel Signaling Network 
Interface Specification (BA-905).

     17.5 Each Party shall charge the other Party mutual and reciprocal rates 
for CCS Signaling as follows: BA shall charge MFS in accordance with Exhibit A 
hereto and applicable Tariffs; MFS shall charge BA rates equal to the rates BA 
charges MFS, unless MFS's Tariffs for CCS signaling provide for lower generally 
available rates, in which case MFS shall charge BA such lower rates.


18.0 COORDINATED SERVICE ARRANGEMENTS.

     18.1 INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its 
service provider from BA to MFS, or from MFS to BA, and does not retain its 
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides

                                      42
<PAGE>
 
details on the Customer's new number or provide other appropriate information to
the extent known. Referral Announcements shall be provided reciprocally, free of
charge to either the other Party or the Customer to the extent the providing
Party does not charge its own customers for such service, for a period of not
less than four (4) months after the date the Customer changes its telephone
number in the case of business Customers and not less than sixty (60) days after
the date the Customer changes its telephone number in the case of residential
Customers. However, if either Party provides Referral Announcements for
different periods than the above respective periods when its Customers change
their telephone numbers, such Party shall provide the same level of service to
Customers of the other Party.

     18.2  COORDINATED REPAIR CALLS. MFS and BA will employ the following
procedures for handling misdirected repair calls:

          18.2.1  MFS and BA will educate their respective Customers as to the
correct telephone numbers to call in order to access their respective repair
bureaus.

          18.2.2  To the extent Party A is identifiable as the correct provider
of service to Customers that make misdirected repair calls to Party B, Party B
will immediately refer the Customers to the telephone number provided by Party
A, or to an information source that can provide the telephone number of Party A,
in a courteous manner and at no charge. In responding to misdirected repair
calls, neither Party shall make disparaging remarks about the other Party, its
services, rates, or service quality.

          18.2.3  MFS and BA will provide their respective repair contact
numbers to one another on a reciprocal basis.

     18.3  CUSTOMER AUTHORIZATION. In order for either Party to order or
terminate service on behalf of the other Party's Customer, the requesting Party
must have proper written authorization from the customer in its files, and
provide a copy of such authorization to the other Party upon request. In the
event the requesting Party (i) fails to provide a copy of the Customer's proper
written authorization upon request, (ii) requests changes in the other Party's
Customer's service without having such authorization in its files, or (iii)
mistakenly changes the other Party's Customer's service, the requesting Party
shall be liable to the other Party for all charges that would be applicable to
the Customer for restoring service to the other Party.


19.0  DIRECTORY SERVICES ARRANGEMENTS

      BA will, upon request, provide the following directory services to MFS in
accordance with the terms set forth herein. In this Section 19, references to a
MFS Customer's "primary listing" shall mean such Customer's name, address, and
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP
arrangements with BA or any other carrier within the geographic area covered in
the relevant BA directory.

                                      43
<PAGE>
 
     19.1   DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

            19.1.1 BA will include the MFS Customer's primary listing in its
"White Pages" directory (residence and business listings) and "Yellow Pages"
directory (business listings) that cover the address of the Customer. Listings
of MFS's Customers will be interfiled with listings of BA's Customers and the
Customers of other LECs included in the BA directories. MFS will pay BA a non-
recurring charge as set forth in Exhibit A for providing such service for each
MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as the
case may be, for additional and foreign white page listings and other white
pages services for MFS's Customers. BA will not require a minimum number of
listings per order.

            19.1.2  BA will also include the MFS Customer's primary listing in
BA's directory assistance database on the same basis that BA's own Customers are
included, as well as in any electronic directories in which BA's Customers are
ordinarily included, for no charge other than the charges identified in
subsection 19.1.1.

            19.1.3  BA will distribute to MFS Customers copies of their primary
white pages and yellow pages directories at the same time and on the same basis
that BA distributes primary directories to its own Customers. BA will also
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional
directories from BA's Directory Fulfillment Centers, which Centers will provide
such additional directories for the same charges applicable to comparable
requests by BA Customers.

            19.1.4  BA will include all MFS NXX codes associated with the areas
to which each directory pertains, along with BA's own NXX codes in any maps or
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same
manner as BA's NXX information.

            19.1.5  MFS shall provide BA with daily listing information on all
new MFS Customers in the format required by BA or a mutually-agreed upon
industry standard format. The information shall include the Customer's name,
address, telephone number, the delivery address and number of directories to be
delivered, and, in the case of a business listing, the primary business heading
under which the business Customer desires to be placed, and any other
information necessary for the publication and delivery of directories. MFS will
also provide BA with daily listing information showing Customers that have
disconnected or terminated their service with MFS. BA will provide MFS with
confirmation of listing order activity within forty eight (48) hours.

            19.1.6  BA will accord MFS's directory listing information the same
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be
used solely for the purpose of providing directory services; provided, however,
that BA may use or license information contained in its directory listings for
direct marketing purposes so long as the MFS Customers are not separately
identified as such; and provided further that MFS may identify those of its
Customers that request

                                      44
<PAGE>
 
that their names not be sold for direct marketing purposes, and BA will honor 
such requests to the same extent as it does for its own Customers.

            19.1.7  BA or BA's publisher shall provide MFS with a report of all
MFS Customer listings ninety (90) days prior to directory publication in such
form and format as may be mutually agreed to by both Parties. Both Parties shall
use their best efforts to ensure the accurate listing of such information. BA
will also provide MFS, upon request, a copy of the BA listings standards and
specifications manual. In addition, BA will provide MFS with a listing of Yellow
Pages headings and directory close schedules on an ongoing basis.

            19.1.8  MFS will adhere to all practices, standards, and ethical
requirements of BA with regard to listings, and, by providing BA with listing
information, warrants to BA that MFS has the right to place such listings on
behalf of its Customers. MFS agrees that it will undertake commercially
practicable and reasonable steps to attempt to ensure that any business or
person to be listed is authorized and has the right (i) to provide the product
or service offered, and (ii) to use any personal or corporate name, trade name
or language used in the listing.

            19.1.9  BA's liability to MFS in the event of a BA error in or
omission of a listing shall be subject to the same limitations that BA's
liability to its own Customers are subject to. In addition, MFS agrees to take,
with respect to its own Customers, all reasonable steps to ensure that its and
BA's liability to MFS's Customers in the event of a BA error in or omission of a
listing shall be subject to the same limitations that BA's liability to its own
Customers are subject to.

     19.2   YELLOW PAGE MAINTENANCE. The Parties agree to work cooperatively to
ensure that Yellow Page advertisements purchased by Customers that switch their
service to MFS (including Customers utilizing MFS-assigned telephone numbers and
MFS Customers utilizing LTNP) are maintained without interruption. BA will allow
MFS Customers to purchase new Yellow Pages advertisements without
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. BA and MFS may implement a commission program whereby MFS may, at
MFS's sole discretion, act as a sales, billing and collection agent for Yellow
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

     19.3   SERVICE INFORMATION PAGES. BA will include in the "Customer Guide" 
or comparable section of the applicable white pages directories listings 
provided by MFS for MFS's installation, repair and customer service and other 
essential service oriented information, as agreed by the Parties, including 
appropriate identifying logo. Such listings shall appear in the manner agreed to
by the Parties. BA shall not charge MFS for inclusion of this essential 
service-oriented information, but reserves the right to impose charges on other 
information MFS may elect to submit and BA may elect to accept for inclusion in 
BA's white pages directories. BA will provide MFS with the annual directory 
close dates and reasonable notice of any changes in said dates.

                                      45
<PAGE>
 
     19.4 DIRECTORY ASSISTANCE (DA); CALL COMPLETION

          19.4.1   Upon request, BA will provide MFS with directory assistance 
and/or call completion services substantially in accordance with the terms set
forth in the form Directory Assistance and Call Completion Services Agreement
appended hereto as Exhibit C.

          19.4.2   Also upon request, BA will provide to MFS operator services 
trunk groups, utilizing Feature Group D type signaling, with ANI, minus OZZ, 
when interconnecting to the BA operator services network.

20.0 COORDINATION WITH TARIFF TERMS

     20.1 The Parties acknowledge that some of the services, facilities, and
arrangements described herein are or will be available under and subject to the
terms of the federal or state tariffs of the other Party applicable to such
services, facilities, and arrangements. To the extent a Tariff of the providing
Party applies to any service, facility, and arrangement described herein, the
Parties agree as follows:

          20.1.1   Those rates and charges set forth in Exhibit A for the
services, facilities, and arrangements described herein that are designated with
an asterisk shall remain fixed for the initial term of the Agreement,
notwithstanding that such rates may be different from those contained in an
effective, pending, or future Tariff of the providing Party (including any
changes to such Tariff subsequent to the Effective Date). Those rates and
charges for services, facilities, and arrangements that are not designated with
an asterisk, and reference or are identical to a rate contained in an existing
Tariff of the providing Party, shall conform with those contained in the then-
prevailing Tariff and vary in accordance with any changes that may be made to
the Tariff rates and charges subsequent to the Effective Date. Even the asterisk
fixed rates and charges shall be changed to reflect any changes in the Tariff
rates and charges they reference, however, if the Parties agree to adopt the
changed Tariff rates and charges.

     20.2 Except with respect to the rates and charges described in subsection
20.1 above, all other terms contained in an applicable Tariff of the providing
Party shall apply in connection with its provision of the particular service,
facility, and arrangement hereunder.

21.0 INSURANCE

     21.1 MFS shall maintain, during the term of this Agreement, all insurance 
and/or bonds required by law and necessary to satisfy its obligations under this
Agreement, including, without limitation, its obligations set forth in Section 
25 hereof. At a minimum and without limiting the foregoing covenant, MFS shall 
maintain the following insurance:

          (a)  Commercial General Liability Insurance, on an occurrence basis, 
     including but not limited to, premises-operations, broad form property
     damage, products/completed

                                      46


<PAGE>
 
     operations, contractual liability, independent contractors, and personal 
     injury, with limits of at least $1,000,000 combined single limit for each 
     occurrence.

          (b)  Automobile Liability, Comprehensive Form, with limits of at least
     $500,000 combined single limit for each occurrence.

          (c)  Excess Liability, in the umbrella form, with limits of at least 
     $15,000,000 combined single limit for each occurrence.

          (d)  Worker's Compensation Insurance as required by law and Employer's
     Liability Insurance with limits of not less than $1,000,000 per occurrence.

     21.2 MFS shall name BA as an additional insured on the foregoing insurance.
MFS agrees that MFS's insurer(s) and anyone claiming by, through, under or on 
behalf of MFS, shall have no claim, right of action, or right of subrogation, 
against BA,  BA's affiliated companies, or the directors, officers or employees 
of BA or BA's affiliated companies, based on any loss or liability insurable 
under the foregoing insurance.

     21.3 MFS shall, within two (2) weeks of the date hereof and on a quarterly
basis thereafter, furnish certificates or other adequate proof of the foregoing
insurance. The certificates or other proof of the foregoing insurance shall be
sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court House
Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall require its
agents, representatives, or contractors, if any, that may enter upon the
premises of BA or BA's affiliated companies to maintain similar and appropriate
insurance and, if requested, to furnish BA certificates or other adequate proof
of such insurance. Certificates furnished by MFS or MFS's agents,
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to
cancellation of, or any material change in, the insurance."


22.0 TERM AND TERMINATION.

     22.1 This Agreement shall be effective as of the date first above written
and continue in effect until July 1, 1999, and thereafter the Agreement shall
continue in force and effect unless and until terminated as provided herein.
Upon the expiration of the initial term, either Party may terminate this
Agreement by providing written notice of termination to the other Party, such
written notice to be provided at least ninety (90) days in advance of the date
of termination. In the event of such termination, those service arrangements
made available under this Agreement and existing at the time of termination
shall continue without interruption under (a) new agreement executed by the
Parties, (b) standard Interconnection terms and conditions approved and made
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of
this Agreement on a month-to-month basis until such time as (a), (b), or (c)
becomes available.

                                      47


<PAGE>
 
     22.2 For service arrangements made available under this Agreement and
existing at the time of termination, if the standard Interconnection terms and
conditions or Tariff terms and conditions result in the non-terminating Party
physically rearranging facilities or incurring programming expense, the 
non-terminating Party shall be entitled to recover such rearrangement or
programming costs, from the terminating Party. By mutual agreement, the Parties
may jointly petition the appropriate regulatory bodies for permission to have
this Agreement supersede any future standardized agreements or rules as such
regulators might adopt or approve.

     22.3 If either Party defaults in the payment of any amount due hereunder,
or if either Party violates any other provision of this Agreement, and such
default or violation shall continue for sixty (60) days after written notice
thereof, the other Party may terminate this Agreement and services hereunder by
written notice; provided the other Party has provided the defaulting Party and
the appropriate federal and/or state regulatory bodies with written notice at
least twenty five (25) days' prior to terminating service. Notice shall be
posted by certified mail, return receipt requested. If the defaulting Party
cures the default or violation within the twenty five (25) day period, the other
Party will not terminate service or this Agreement but shall be entitled to
recover all costs, if any, incurred by it in connection with the default or
violation, including, without limitation, costs incurred to prepare for the
termination of service.

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES ANY
WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE PARTIES
DISCLAIM THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A
PARTICULAR PURPOSE.

24.0 CANCELLATION CHARGES.

     Except as provided in this Agreement or as otherwise provided in any 
applicable Tariff, no cancellation charges shall apply.

25.0 INDEMNIFICATION.

     25.1 Each Party agrees to release, indemnify, defend and hold harmless the
other Party from and against all losses, claims, demands, damages, expenses,
suits or other actions, or any liability whatsoever, including, but not limited
to, costs and attorneys' fees (collectively, a "Loss"), (a) whether suffered,
made, instituted, or asserted by any other party or person, (i) relating to
personal injury to or death of any person, or for loss, damage to, or
destruction of real and/or personal property, whether or not owned by others,
incurred during the term of this Agreement and to the extent proximately caused
by the acts or omissions of the indemnifying Party, regardless of the form of
action, or (ii) arising out of BA's listing of the directory listing information
provided by

                                      48

<PAGE>
 
MFS pursuant to subsection 19.1, or (b) suffered, made, instituted, or asserted
by its own customer(s) against the other Party arising out the other Party's
provision of services to the indemnifying Party under this Agreement.
Notwithstanding the foregoing indemnification, nothing in this such Section 25.
shall affect or limit any claims, remedies, or other actions the indemnifying
Party may have against the indemnified Party under this Agreement, any other
contract, or any applicable Tariff(s), regulations or laws for the indemnified
Party's provision of said services.

     25.2 The indemnification provided herein shall be conditioned upon:

          (a) The indemnified Party shall promptly notify the indemnifying
     Party of any action taken against the indemnified Party relating to the
     indemnification.

          (b) The indemnifying Party shall have sole authority to defend any
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c) In no event shall the indemnifying Party settle or consent to any
     judgment pertaining to any such action without the prior written consent of
     the indemnified Party, which consent shall not be unreasonably withheld.

          (d) The indemnified Party shall, in all cases, assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e) The indemnified Party shall offer the indemnifying Party all
     reasonable cooperation and assistance in the defense of any such action.

      25.3 In addition to its indemnity obligations under subsection 25.1, each
Party shall provide, in its tariffs and contracts with its Customers that relate
to any Telecommunications Service or Network Element provided or contemplated
under this Agreement, that in no case shall such Party or any of its agents,
contractors or others retained by such parties be liable to any Customer or
third party for (i) any Loss relating to or arising out of this Agreement,
whether in contract or tort, that exceeds the amount such Party would have
charged the applicable Customer for the service(s) or function(s) that gave rise
to such Loss, and (ii) any Consequential Damages (as defined in subsection 26.2
below).


26.0  LIMITATION OF LIABILITY.

      26.1 Except as may be provided pursuant to Section 27 below, the liability
of either Party to the other Party for damages arising out of failure to comply
with a direction to install, restore or terminate facilities; or out of
failures, mistakes, omissions, interruptions, delays, errors, or defects
occurring in the course of furnishing any services, arrangements, or facilities
hereunder shall be determined in accordance with the terms of the applicable
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro

                                      49
<PAGE>
 
rata monthly charge for the period in which such failures, mistakes, omissions,
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for
such failures, mistakes, omissions, interruptions, delays, errors or defects.

     26.2 Neither Party shall be liable to the other in connection with the
provision or use of services offered under this Agreement for indirect,
incidental, consequential, reliance or special damages, including (without
limitation) damages for lost profits (collectively, "Consequential Damages"),
regardless of the form of action, whether in contract, warranty, strict
liability, or tort, including, without limitation, negligence of any kind, even
if the other Party has been advised of the possibility of such damages;
provided, that the foregoing shall not limit a Party's obligation under Section
25.

     26.3 The Parties agree that neither Party shall be liable to the customers
of the other Party in connection with its provision of services to the other
Party under this Agreement. Nothing in this Agreement shall be deemed to create
a third party beneficiary relationship between the Party providing the service
and the customers of the Party purchasing the service. In the event of a dispute
involving both Parties with a customer of one Party, both Parties shall assert
the applicability of any limitations on liability to customers that may be
contained in either Party's applicable Tariff(s).


27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

     27.1 CERTAIN DEFINITIONS. When used in this Section 27, the following
terms shall have the meanings indicated:

          27.1.1  "Specified Performance Breach" means the failure by BA to meet
the Performance Criteria for any one of the three Specified Activities for a
period of three (3) consecutive calendar months.

          27.1.2  "Specified Activity" means any of the following activities:

          (a)  the installation by BA of Unbundled Local Loop Elements for MFS
     ("ULL Installation");

          (b)  BA's provision of INP to MFS or

          (c)  repair of out of service problems for MFS ("Out of Service
     Repairs").

          27.1.3  "Performance Criteria" means, with respect to any calendar
month during the term of this Agreement, the performance by BA during such month
of each Specified Activity (except Out-of-Service Repairs) shown in Schedule
27.0, within the time interval shown, in at least eighty percent (80%) of the
covered instances.  BA shall perform the Out-of-Service Repairs within the
specified time interval in at least seventy percent (70%) of the covered

                                      50
<PAGE>
 
instances. Within one week of each anniversary of the Effective Date, the 
Parties shall jointly review BA's actual network-wide monthly performance 
percentages for Out-of-Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual 
percentages for any three consecutive month period and/or the full preceding 
year, up to and including an eighty percent (80%) standard, as the 
Out-of-Service Repairs percentage standard applicable to the following year.

     27.2  PERFORMANCE STANDARDS. BA shall exercise best efforts to meet the 
Performance Criteria for the three Specified Activities. In the event BA fails 
to meet the Performance Criteria at any time during the term of this Agreement, 
MFS shall be entitled to pursue all remedies set forth in the applicable BA 
Tariffs, except as may be agreed to by the Parties. In addition, if BA commits a
Specified Performance Breach during the term of this Agreement, the Parties 
agree to meet immediately to determine whether any liquidated damages provisions
are appropriate as an amendment hereof in light of such Breach and, if so, the 
terms therein; provide, however, that if BA commits a Specified Performance 
Breach during initial nine (9) months of this Agreement, the Parties agree to 
meet at the end of the nine-month period. If the Parties are unable to agree as 
to the appropriateness of the liquidated damages provisions and/or the terms 
therein within ninety (90) days after the date of the first meeting pursuant to 
this subsection, or if no such meeting has occurred within ninety (90) days of 
the end of the nine-month period for reasons other than the mutual agreement of 
the Parties, the Parties agree to submit to arbitration such disagreement and 
request that the arbitrators base their decision on comparable ILEC-CLEC 
interconnection agreements. Unless otherwise agreed to by the Parties, the 
arbitration shall be conducted by a panel of three (3) arbitrators, one to be 
appointed by each Party pursuant to CPR's Non-Administered Arbitration Rules and
subject to the United States Arbitration Act (9 U.S.C (S)(S) 1-16), to be
conducted in Arlington, Virginia. The Parties agree that the liquidated damages
provisions, if any, finally determined by the arbitral process shall be adopted
as an amendment to this Agreement.

     27.3  LIMITATIONS. In no event shall BA be deemed to have failed to meet 
any of the Performance Criteria if:

           27.3.1   BA's failure to meet or exceed any of the Performance 
Criteria is caused, directly or indirectly, by a Delaying Event. A "Delaying 
Event" means (a) a failure by MFS to perform any of its obligations set forth in
this Agreement (including, without limitation, the Implementation Schedule and 
the Joint Grooming Plan), (b) any delay, act or failure to act by a Customer,
agent, representative, or subcontractor of MFS or (c) any Force Majeure Event. 
If a Delaying Event prevents or delays BA from performing a Specified Activity, 
then such Specified Activity shall be excluded from the calculation of BA's 
compliance with the Performance Criteria, provided BA performs the Specified 
Activity in the course of its normal service cycle once the Delaying Event no 
longer exists; or

           27.3.2   the Parties agree to a time interval with respect to a 
particular order that exceeds the interval set forth in Schedule 27. In such 
event, the time interval for BA's performance of the Specified Activit(ies) set 
forth in the order shall be extended to such later date agreed to by the 
Parties.

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<PAGE>
 
     27.4 SERVICE QUALITY STANDARDS. MFS agrees to specific performance
standards associated with quality of service requests as specified in Schedule
27.1. Should MFS fail to meet these service quality standards, during a period
in which BA has failed to meet the Performance Criteria, BA's failure during
such time period shall be excused and not apply toward the calculation of a
Specified Performance Breach.

     27.5 RECORDS. Each Party shall maintain complete and accurate records in
the manner and format agreed to by the Parties, on a monthly basis, of BA's
performance under this Agreement of each Specified Activity and its compliance
with the Performance Criteria during the initial nine-month period. Each Party
shall provide to the other Party such records in a self-reporting format on a
monthly basis. The Parties agree that such records shall be deemed "Proprietary
Information" for purposes of subsection 29.4.


28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

     28.1 Each Party represents and warrants that it is now and will remain in
compliance with all laws, regulations, and orders applicable to the performance
of its obligations hereunder (collectively, "Applicable Laws"). Each Party shall
promptly notify the other Party in writing of any governmental action that
suspends, cancels, withdraws, limits, or otherwise materially affects its
ability to perform its obligations hereunder.

     28.2 The Parties understand and agree that this Agreement will be filed
with the Commission and may thereafter be filed with the FCC. The Parties
covenant and agree that this Agreement is satisfactory to them as an agreement
under Section 251 of the Act. Each Party covenants and agrees to fully support
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek
regulatory relief and otherwise seek redress from each other regarding
performance and implementation of this Agreement.

     28.3 The Parties recognize that the FCC is currently promulgating
regulations implementing the Act, including, without limitation, Sections 251,
252, and 271 thereof (the "FCC Regulations"), that may affect the terms
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties
agree to make only the minimum revisions necessary to eliminate the
inconsistency. Such minimum changes to conform this Agreement to the FCC
Regulations shall not be considered material, and shall not require further
Commission approval (beyond any Commission approval required under Section
252(e) of the Act).

     28.4 In the event any Applicable Law other than the FCC Regulations
requires modification of any material term(s) contained in this Agreement,
either Party may require a renegotiation of the term(s) that require direct
modification as well as of any term(s) that are reasonably affected thereby. If
neither Party requests a renegotiation or if an Applicable Law requires
modification of any non-material term(s), then the Parties agree to make only 
the minimum

                                      52
<PAGE>
 
modifications necessary, and the remaining provisions of this Agreement shall
remain in full force and effect. For purposes of this subsection 28.4 and
without limitation of any other modifications required by Applicable Laws, the
Parties agree that any modification required by Applicable Laws (i) to the two-
tier Reciprocal Call Termination compensation structure for the transport and
termination of Local Traffic described in Exhibit A, or (ii) that affects either
Party's receipt of reciprocal compensation for the transport and termination of
Local Traffic, shall be deemed to be a modification of a material term that
requires immediate good faith renegotiation between the Parties. Until such
renegotiation results in a new agreement or an amendment to this Agreement
between the Parties, the Parties agree that (y) in the case of (i) above, they
will pay each other appropriate transport charges in addition to the usual call
termination charge for Local Traffic that it delivers to the other Party's Local
Serving Wire Center, provided each Party continues to offer the option of
delivering Local Traffic to another IP in the LATA at the usual call termination
charge only, and (z) in the case of (ii) above, the Party whose receipt of
reciprocal compensation is affected shall not be obligated to pay the other
Party reciprocal compensation for the other Party's transport and termination of
the same kind of Local Traffic delivered by the affected Party in excess of what
the affected Party is permitted to receive and retain.


29.0  MISCELLANEOUS.

      29.1  AUTHORIZATION.

            29.1.1  BA is a corporation duly organized, validly existing and in
good standing under the laws of the Commonwealth of Virginia and has full power
and authority to execute and deliver this Agreement and to perform the
obligations hereunder on behalf of BA.

            29.1.2  MFS is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware and has full power and
authority to execute and deliver this Agreement and to perform its obligations
hereunder.

      29.2  INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder
as an independent contractor and nothing herein shall be construed as creating
any other relationship between the Parties. Each Party and each Party's
contractor shall be solely responsible for the withholding or payment of all
applicable federal, state and local income taxes, social security taxes and
other payroll taxes with respect to their employees, as well as any taxes,
contributions or other obligations imposed by applicable state unemployment or
workers' compensation acts. Each Party has sole authority and responsibility to
hire, fire and otherwise control its employees.

      29.3  FORCE MAJEURE. Neither Party shall be responsible for delays or
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in
performance were foreseen or foreseeable as of the date of this Agreement,
including, without limitation: adverse weather conditions, fire, explosion,
power failure, acts of God, war, revolution, civil commotion, or acts of public
enemies; any law, order, regulation, ordinance or requirement of any government
or legal body; or labor unrest, including, without limitation, strikes,
slowdowns, picketing or boycotts; or delays caused by the

                                      53
<PAGE>
 
other Party or by other service or equipment vendors; or any other circumstances
beyond the Party's reasonable control. In such event, the affected Party shall,
upon giving prompt notice to the other Party, be excused from such performance
on a day-to-day basis to the extent of such interferences (and the other Party
shall likewise be excused from performance of its obligations on a day-for-day
basis to the extent such Party's obligations relate to the performance so
interfered with). The affected Party shall use its best efforts to avoid or
remove the cause(s) of non-performance and both Parties shall proceed to perform
with dispatch once the cause(s) are removed or cease.

     29.4 CONFIDENTIALITY.

          29.4.1  All information, including but not limited to specification,
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches,
models, samples, tools, technical information, data, employee records, maps,
financial reports, and market data, (i) furnished by one Party to the other
Party dealing with customer specific, facility specific, or usage specific
information, other than customer information communicated for the purpose of
publication or directory database inclusion, or (ii) in written, graphic,
electromagnetic, or other tangible form and marked at the time of delivery as
"Confidential" or "Proprietary," or (iii) communicated orally and declared to
the receiving Party at the time of delivery, or by written notice given to the
receiving Party within ten (10) days after delivery, to be "Confidential" or
"Proprietary" (collectively referred to as "Proprietary Information"), shall
remain the property of the disclosing Party.

          29.4.2  Each Party shall keep all of the other Party's Proprietary
Information confidential and shall use the other Party's Proprietary Information
only for performing the covenants contained in this Agreement. Neither Party
shall use the other Party's Proprietary Information for any other purpose except
upon such terms and conditions as may be agreed upon between the Parties in
writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality
and non-use set forth in this Agreement do not apply to such Proprietary
Information that:

          (a) was, at the time of receipt, already known to the receiving Party
     free of any obligation to keep it confidential as evidenced by written
     records prepared prior to delivery by the disclosing Party; or

          (b) is or becomes publicly known through no wrongful act of the
     receiving Party; or

          (c) is rightfully received from a third person having no direct or
     indirect secrecy or confidentiality obligation to the disclosing Party with
     respect to such information; or

          (d) is independently developed by an employee, agent, or contractor of
     the receiving Party that is not involved in any manner with the provision
     of services pursuant to this Agreement and does not have any direct or
     indirect access to the Proprietary Information; or

                                      54
<PAGE>
 
          (e)     is approved for release by written authorization of the 
     disclosing Party; or

          (f)     is required to be made public by the receiving Party pursuant
     to applicable law or regulation, provided that the receiving Party shall
     give sufficient notice of the requirement to the disclosing Party to enable
     the disclosing Party to seek protective orders.

          29.4.4  Upon request by the disclosing Party, the receiving Party 
shall return all tangible copies of Proprietary Information, whether written,
graphic or otherwise, except that the receiving Party may retain one copy for
archival purposes only.

          29.4.5  Notwithstanding any other provision of this Agreement, the 
provisions of this subsection 29.4 shall apply to all Proprietary Information
furnished by either Party to the other in furtherance of the purpose of this
Agreement, even if furnished before the Effective Date.

     29.5 CHOICE OF LAW.  The construction, interpretation and performance of 
this Agreement shall be governed by and construed in accordance with the laws of
the state in which this Agreement is to be performed, except for its conflicts
of laws provisions.  In addition, insofar as and to the extent federal law may
apply, federal law will control.

     29.6 TAXES

          29.6.1. In General. With respect to any purchase hereunder of 
                  ----------
services, facilities or arrangements, if any federal, state or local tax, fee,
surcharge or other tax-like charge (a "Tax") is required or permitted by
Applicable Law (as defined in subsection 28.1) to be collected from the
purchasing Party by the providing Party, then (i) the providing Party shall
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

          29.6.2. Taxes Imposed on the Providing Party. With respect to any 
                  ------------------------------------  
purchase hereunder of services, facilities or arrangements, if any federal,
state or local Tax is imposed by Applicable Law on the receipts of the providing
Party, which law permits the providing Party to exclude certain receipts 
received from sales for resale to a public utility, distributor, telephone 
company ("Telecommunications Company"), such exclusion being based solely on the
fact that the purchasing Party is also subject to a tax based upon receipts
("Receipts Tax"), then the purchasing Party (i) shall provide the providing 
Party with notice in writing in accordance with subsection 29.6.6 of this 
Agreement of its intent to pay the Receipts Tax and (ii) shall timely pay the
Receipts Tax to the applicable tax authority.
 
          29.6.2. Taxes Imposed on Customers. With respect to any purchase 
                  --------------------------  
hereunder of services, facilities or arrangements that are resold to a third 
party, if any federal, state or local Tax is imposed by Applicable Law on the 
subscriber, end-user, Customer or ultimate consumer ("Subscriber") in 
connection with any such purchase, which a Telecommunications Company is

                                      55 

 

<PAGE>
 
required to impose and/or collect from a Subscriber, then the purchasing Party 
(i) shall be required to impose and/or collect such Tax from the Subscriber and 
(ii) shall timely remit such Tax to the applicable taxing authority.

               29.6.4 Liability for Uncollected Tax, Interest and Penalty. If
                      ---------------------------------------------------
the providing Party has not received an exemption certificate and fails to
collect any Tax as required by subsection 29.6.1, then, as between the providing
Party and the purchasing Party, (i) the purchasing Party shall remain liable for
such uncollected Tax and (ii) the providing Party shall be liable for any
interest assessed thereon and any penalty assessed with respect to such
uncollected Tax by such authority. If the providing Party properly bills the
purchasing Party for any Tax but the purchasing Party fails to remit such Tax to
the providing Party as required by subsection 29.6.1, then, as between the
providing Party and the purchasing Party, the purchasing Party shall be liable
for such uncollected Tax and any interest assessed thereon, as well as any
penalty assessed with respect to such uncollected Tax by the applicable taxing
authority. If the providing Party does not collect any Tax as required by
subsection 29.6.1 because the purchasing Party has provided such providing Party
with an exemption certificate that is later found to be inadequate by a taxing
authority, then, as between the providing Party and the purchasing Party, the
purchasing Party shall be liable for such uncollected Tax and any interest
assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. If the purchasing Party
fails to pay the Receipts Tax as required by subsection 29.6.2, then, as between
the providing Party and the purchasing Party, (x) the providing Party shall be
liable for any tax imposed on its receipts and (y) the purchasing Party shall be
liable for any interest assessed thereon and any penalty assessed upon the
providing Party with respect to such Tax by such authority. If the purchasing
party fails to impose and/or collect any Tax from Subscribers as required by
subsection 29.6.3, then, as between the providing Party and the purchasing
Party, the purchasing Party shall remain liable for such uncollected Tax and any
interest assessed thereon, as well as any penalty assessed with respect to such
uncollected Tax by the applicable taxing authority. With respect to any Tax that
the purchasing Party has agreed to pay, or is required to impose on and/or
collect from Subscribers, the purchasing Party agrees to indemnify and hold the
providing Party harmless on an after-tax basis for any costs incurred by the
providing Party as a result of actions taken by the applicable taxing authority
to recover the Tax from the providing Party due to the failure of the purchasing
Party to timely pay, or collect and timely remit, such Tax to such authority. In
the event either Party is audited by a taxing authority, the other Party agrees
to cooperate fully with the Party being audited in order to respond to any audit
inquiries in a proper and timely manner so that the audit and/or any resulting
controversy may be resolved expeditiously.

               29.6.5. Tax Exemptions and Exemption Certificates. If Applicable
                       -----------------------------------------  
Law clearly exempts a purchase hereunder from a Tax, and if such Law also
provides an exemption procedure, such as an exemption-certificate requirement,
then, if the purchasing Party complies with such procedure, the providing Party
shall not collect such Tax during the effective period of such exemption. Such
exemption shall be effective upon receipt of the exemption certificate or
affidavit in accordance with the terms set forth in subsection 29.6.6. If
Applicable Law clearly exempts a purchase hereunder from a Tax, but does not
also provide an exemption procedure, then the providing Party shall not collect
such Tax if the purchasing Party (i) furnishes the

                                      56
<PAGE>
 
providing Party with a letter signed by an officer requesting such an exemption 
and citing the provision in the Law which clearly allows such exemption and 
(ii) supplies the providing Party with an indemnification agreement, reasonably 
acceptable to the providing Party (e.g., an agreement commonly used in the 
industry), which holds the providing Party harmless on an after-tax basis with 
respect to its forbearing to collect such Tax.

          29.6.6. Notices for Purposes of this Subsection 29.6. All notices, 
                  ---------------------------------------------
affidavits, exemption-certificates or other communications required or permitted
to be given by either Party to the other, for purposes of this subsection 29.6,
shall be made in writing and shall be delivered in person or sent by certified
mail, return receipt requested, or registered mail, or a courier service
providing proof of service, and sent to the addressees set forth in subsection
29.10 as well as to the following:

     To Bell Atlantic:        Tax Administration 
                              Bell Atlantic Network Services, Inc.
                              1717 Arch Street
                              30th Floor 
                              Philadelphia, PA 19103

     To MFS:                  Corporate Tax Department
                              MFS Communications Company, Inc.
                              11808 Miracle Hills Drive
                              Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addressees
by giving notice is accordance with the terms of this subsection 29.6. Any 
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT. Neither Party shall assign this Agreement nor any of its 
rights or obligations hereunder without the prior written consent of the other
Party, which consent shall not be unreasonably withheld. Any assignment or
delegation in violation of this subsection 29.7 shall be void and ineffective
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS.

          29.8.1 Except may otherwise be provided in this Agreement, each Party 
shall submit on a monthly basis an itemized statement of charges incurred by 
the other Party during the preceding month(s) for services rendered hereunder.
Payment of billed amounts under this Agreement, whether billed on a monthly
basis or as otherwise provided herein, shall be due, in immediately available
U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2 Although it is the intent of both Parties to submit timely and 
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or
a waiver of the right to payment of the incurred charges, by the billing Party
under this Agreement, and the billed Party shall not be entitled to

                                      57

<PAGE>
 
dispute the billing Party' statement(s) based on such Party's failure to submit 
them in a timely fashion.

           29.8.3   If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60) days 
of its receipt of the invoice containing such disputed amount give notice to the
Billing Party of the amounts it disputes ("Disputed Amounts") and include in 
such notice the specific details and reasons for disputing each item. The 
Non-Paying Party shall pay when due (i) all undisputed amounts to the Billing 
Party and (ii) all Disputed Amounts into an interest bearing escrow account with
a third party escrow agent mutually agreed upon by the Parties.

           29.8.4   If the Parties are unable to resolve the issues related to 
the Disputed Amounts in the normal course of business within ninety (90) days 
after delivery to the Billing Party of notice of the Disputed Amounts, each of 
the Parties shall appoint a designated representative that has authority to 
settle the dispute and that is at a higher level of management than the persons 
with direct responsibility for administration of this Agreement. The designated 
representatives shall meet as often as they reasonably deem necessary in order 
to discuss the dispute and negotiate in good faith in an effort to resolve such 
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant 
information made by one Party to the other Party shall be honored.

           29.8.5   If the Parties are unable to resolve issues related to the 
Disputed Amounts within forty-five (45) days after the Parties' appointment of 
designated representatives pursuant to subsection 29.8.4, then either Party may 
file a complaint with the Commission to resolve such issues or proceed with any 
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus 
applicable late fees, to be paid to either Party.

           29.8.6   The Parties agree that all negotiations pursuant to this 
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state 
rules of evidence.

           29.8.7   Any undisputed amounts not paid when due shall accrue
interest from the date such amounts were due at the lesser of (i) one and one-
half percent (1-1/2%) per month or (ii) the highest rate of interest that may be
charged under applicable law.

     29.9  DISPUTE RESOLUTION. Any dispute between the Parties regarding the 
interpretation or enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial 
forum of component jurisdiction.

                                      58

<PAGE>
 
     29.10   NOTICES. Notices given by one Party to the other Party under this 
Agreement shall be in writing and shall be (a) delivered personally, (b) 
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by 
telecopy to the following addresses of the Parties:

             To MFS:

             MFS Intelenet of Virginia, Inc.
             33 Whitehall St.
             15th Floor
             New York, NY 10004
             Attn: Director, Regulatory Affairs - Eastern Region
             Facsimile: 212/843-3060

             To Bell Atlantic:

             Director - Interconnection Services
             Bell Atlantic Network Services, Inc.
             1320 N. Courthouse Road
             9th Floor
             Arlington, VA 22201
             Facsimile: 703/974-2183

             with a copy to:

             Vice President and General Counsel
             Bell Atlantic - Virginia, Inc.
             600 East Main Street 
             24th Floor
             Richmond, VA 23261
             Facsimile: (804) 772-2143

or to such other address as either Party shall designate by proper notice. 
Notices will be deemed given as of the earlier of (i) the date of actual receipt
(ii) the next business day when notice is sent via express mail or personal
delivery, (iii) three (3) days after mailing in the case of first class or
certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of telecopy.

     29.11   SECTION 252(I) OBLIGATIONS.

             29.11.1 If, at any time during the term of this Agreement, either 
Party enters into an agreement to provide an integrated package of services or 
arrangements substantially similar to that described herein to another CLEC (in 
the case of BA), or another incumbent LEC (in the case of MFS), operating within
the same state to which this Agreement applies, on terms significantly

                                      59
<PAGE>
 
different than those available under this Agreement (the "Other Agreement"),
then the other Party may opt to adopt, on a prospective basis only, the rates,
terms, and conditions contained in the Other Agreement (i) in its entirety, or
(ii) that relate directly to any of the following individual services, Network
Elements, or arrangements, for its own reciprocal arrangements with the first 
Party, including, without limitation, any term or volume commitments or network
architecture configurations:

          (a)   Unbundled Loop Elements - Section 251(c)(3) of the Act (Section
     11 of this Agreement); or

          (b)   Collocation - Section 251(c)(6) of the Act (Section 13 of this
     Agreement); or

          (c)   Number Portability - Section 251(b)(2) of the Act (Section 14 of
     this Agreement); or           

          (d)   Access to Rights of Way - Section 251(b)(4) of the Act (Section
     16 of this Agreement).

          (e)   transiting arrangements.

          29.11.2  To the extent the exercise of the foregoing options requires
a rearrangement of facilities by the providing Party, the opting Party shall be
liable for the non-recurring charges associated therewith.

          29.11.3  The Party electing to exercise such option shall do so by 
delivering written notice to the first Party. Upon receipt of said notice by the
first Party, the Parties shall amend this Agreement to provide the same rates, 
terms and conditions to the notifying Party for the remaining term of this 
Agreement; provided, however, that the Party exercising its option under this
subsection 29.11 must continue to provide the same services or arrangements to
the first Party as required by this Agreement, subject either to the rates,
terms, and conditions applicable to the first Party in its agreement with the
third party or to the rates, terms, and conditions of this Agreement, whichever
is more favorable to the first Party in its sole determination.

          29.11.4  BA represents and warrants that, as of the date of this 
Agreement, it has not entered into any comparable Interconnection agreement with
any other CLEC in BA's service territory that is significantly more favorable
than the terms contained herein. BA makes no warranty or representation with
respect to its Interconnection arrangements with its affiliates or ITCs.

     29.12  JOINT WORK PRODUCT.  This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and 
shall be fairly interpreted in accordance with its terms and, in the event of 
any ambiguities, no inferences shall be drawn against either Party.

                                      60
<PAGE>
 
     29.13  NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. This Agreement 
is for the sole benefit of the Parties and their permitted assigns, and nothing 
herein express or implied shall create or be construed to create any third-party
beneficiary rights hereunder. Except for provisions herein expressly authorizing
a Party to act for another, nothing in this Agreement shall constitute a Party
as a legal representative or agent of the other Party, not shall a Party have
the right or authority to assume, create or incur any liability or any
obligation of any kind, express or implied, against or in the name or on behalf
of the other Party unless otherwise expressly permitted by such other Party.
Except as otherwise expressly provided in this Agreement, no Party undertakes to
perform any obligation of the other Party, whether regulatory or contractual, or
to assume any responsibility for the management of the other Party's business.

     29.14  NO LICENSE.

            29.14.1  Nothing in this Agreement shall be construed as the grant 
of a license, either express or implied, with respect to any patent, copyright, 
trademark, trade name, trade secret or any other proprietary or intellectual 
property now or hereafter owned, controlled or licensable by either Party. 
Neither Party may use any patent, copyrightable materials, trademark, trade 
name, trade secret or other intellectual property right of the other Party 
except in accordance with the terms of a separate license agreement between the 
Parties granting such rights.

            29.14.2  Neither Party shall have any obligation to defend, 
indemnify or hold harmless, or acquire any license or right for the benefit of, 
or owe any other obligation or have any liability to, the other Party or its 
customers based on or arising from any claim, demand, or proceeding by any third
party alleging or asserting that the use of any circuit, apparatus, or system, 
or the use of any software, or the performance of any service or method, or the 
provision of any facilities by either Party under this Agreement, alone or in 
combination with that of the other Party, constitutes direct, vicarious or 
contributory infringement or inducement to infringe, misuse or misappropriation 
of any patent, copyright, trademark, trade secret, or any other proprietary or 
intellectual property right of any Party or third party. Each Party, however, 
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

            29.14.3  NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE 
PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, ANY 
WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S 
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT 
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR 
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15  TECHNOLOGY UPGRADES. Nothing in this Agreement shall limit BA's 
ability to upgrade its network through the incorporation of new equipment, new 
software or otherwise. BA shall provide MFS written notice at least ninety (90) 
days prior to the incorporation of any such upgrades in BA's network that will 
materially affect MFS's service. MFS shall be solely responsible for the cost 
and effort of accommodating such changes in its own network.

                                      61

<PAGE>
 
     29.16  SURVIVAL. The Parties' obligations under this Agreement which by 
their nature are intended to continue beyond the termination or expiration of 
this Agreement shall survive the termination or expiration of this Agreement.

     29.17  ENTIRE AGREEMENT. The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other documents or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with respect to the subject matter 
hereof, superseding all prior understandings, proposals and other 
communications, oral or written. Neither Party shall be bound by any preprinted 
terms additional to or different from those in this Agreement that may appear 
subsequently in the other Party's form documents, purchase orders, quotations, 
acknowledgments, invoices or other communications.

     29.18  COUNTERPARTS. This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19  MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No modification, 
amendment, supplement to, or waiver of the Agreement or any of its provisions 
shall be effective and binding upon the Parties unless it is made in writing and
duly signed by the Parties. A failure or delay of either Party to enforce any of
the provisions hereof, to exercise any option which is herein provided, or to 
require performance of any of the provisions hereof shall in no way be construed
to be a waiver of such provisions or options.

     29.20  SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and inure
to the benefit of the Parties and their respective legal successors and 
permitted assigns.

     29.21  PUBLICITY. Neither Party shall use the name of the other Party in 
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      62

<PAGE>
 
          IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to 
be executed as of this 16th day of July, 1996.


MFS INTELENET OF                             BELL ATLANTIC - 
VIRGINIA, INC.                               VIRGINIA, INC.

By:  /s/ Alex J. Harris                      By:  /s/ H.R. Stallard
   ---------------------------------------      --------------------------------
Printed: Alex J. Harris                      Printed: H.R. Stallard
        ----------------------------------           ---------------------------
Title:   Vice President Regulatory Affairs   Title:   PRES. / CEO - BA - VA
      ------------------------------------         -----------------------------

                                      63

<PAGE>
 
SCHEDULE 1.0

CERTAIN TERMS AS DEFINED IN THE ACT, AS OF JULY 16, 1996

     "Dialing Parity" means that a person that is not an affiliate of a local 
exchange carrier is able to provide Telecommunications Services in such a manner
that Customers have the ability to route automatically, without the use of any 
access code, their Telecommunications to the Telecommunications Services 
provider of the customer's designation from among two (2) or more 
Telecommunications Services providers (including such LEC).

     "Exchange Access" means the offering of access to Telephone Exchange 
Services or facilities for the purpose of the origination or termination of
Telephone Toll Services.

     "InterLATA" means Telecommunications between a point located in a local 
access and transport area and a point located outside such area.

     "Local Access and Transport Area" or "LATA" means a contiguous geographic 
area: (a) established before the date of enactment of the Act by a Bell 
operating company such that no Exchange Area includes points within more than 
one (1) metropolitan statistical area, consolidated metropolitan statistical 
area, or State, except as expressly permitted under the AT&T Consent Decree; or 
(b) established or modified by a Bell operating company after such date of 
enactment and approved by the FCC.

     "Local Exchange Carrier" means any person that is engaged in the provision 
of Telephone Exchange Service or Exchange Access.  Such term does not include a 
person insofar as such person is engaged in the provision of a commercial mobile
service under Section 332(c) of the Act, except to the extent that the FCC finds
that such service should be included in the definition of such term. 

     "Network Element" means a facility or equipment used in the provision of
a Telecommunications Service.  Such term also includes features, functions, and 
capabilities that are provided by means of such facility or equipment, including
subscriber numbers, databases, signaling systems, and information sufficient for
billing and collection or used in the transmission, routing, or other provision 
of a Telecommunications Service.

     "Number Portability" means the ability of end users of telecommunications 
services to retain, at the same location, existing telecommunications numbers 
without impairment of quality, reliability, or convenience when switching from 
one telecommunications carrier to another.

     "Telecommunications" means the transmission, between or among points 
specified by the user, of information of the user's choosing, without change in 
the form or content of the information as sent and received.
<PAGE>
 
     "Telecommunications Carrier" means any provider of Telecommunications 
Services, except that such term does not include aggregators of 
Telecommunications Services (as defined in Section 226 of the Communications 
Act).

     "Telecommunications Service" means the offering of Telecommunications for a
fee directly to the public, or to such classes of users as to be effectively
available directly to the public, regardless of the facilities used.

     "Telephone Exchange Service" means (a) service within a telephone exchange 
or within a connected system of telephone exchanges within the same exchange 
area operated to furnish subscribers intercommunicating service of the character
ordinarily furnished by a single exchange, and which is covered by the exchange 
service charge, or (b) comparable service provided through a system of switches,
transmission equipment, or other facilities (or combination thereof) by which a 
subscriber can originate and terminate a telecommunications service.
     
     "Telephone Toll Service" means telephone service between stations in 
different exchange areas for which there is made a separate charge not included 
in contracts with subscribers for exchange service.
<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA


     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
than the listed Dates.

<TABLE> 
<CAPTION> 
======================================================================================================
LATA IN VIRGINIA         MILESTONE                                              DATE
- ------------------------------------------------------------------------------------------------------
<S>                      <C>                                                    <C> 
LATA 236                 LATA Start Date ("SD")                                 Effective Date
                         -----------------------------------------------------------------------------
                         SS7 Certification, Collocation, and NXX(s)             SD plus 15 days
                         Applied For 
                         -----------------------------------------------------------------------------
                         Parties Agree on Initial Network Design                SD plus 30 days
                         -----------------------------------------------------------------------------
                         Valid Access Service Request(s) ("ASRs") and           SD plus 45 days
                         Routing Information Received by BA
                         -----------------------------------------------------------------------------
                         Collocation Arrangements Complete for Trunk            SD plus 135 days
                         Interconnection and IDLC for ULLs
                         -----------------------------------------------------------------------------
                         All Trunks Tested and Turned Up; SS7 Certification     SD plus 155 days
                         Achieved; /1/ VG ULL Capability Available
                         ----------------------------------------------------------------------------- 
                         Call-through Testing Completed;                        SD plus 180 days   
                         "Interconnection Activation Date"
- ------------------------------------------------------------------------------------------------------
</TABLE> 

     Failure of a Party or the Parties to meet an earlier Milestone Date shall 
not relieve either Party of the responsibility to make its best efforts to meet 
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that, 
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when
MFS has an effective Tariff for business Telephone Exchange Service in the 
Commonwealth of Virginia and has a significant number of Telephone Exchange 
Service Customer lines in service for business Telephone Exchange Service
Customers in that LATA in the Commonwealth of Virginia that are not affiliates
or employees of either BA or MFS, and (ii) residential Telephone Exchange
Service shall be considered "fully operational" in a LATA in the Commonwealth of
Virginia when MFS has an effective Tariff for residential Telephone Exchange
Service in the Commonwealth of Virginia and has a significant number of
Telephone Exchange Service Customer lines in service for residential Telephone
Exchange Service Customers in that LATA in the Commonwealth of Virginia that are
not affiliates or employees of either BA or MFS.


______________________________
/1/   SS7 certification scheduling depends on actual schedule availability at
time of request.

                                       1
<PAGE>
 
SCHEDULE 4

INTERCONNECTION POINTS IN LATA


                                   LATA 236
                                   --------

M-IP:  Reston Switch
       12379 Sunrise Valley Dr.
       Reston, VA

BA-IP  Arlington Tandem
       1025 N. Irving Street
       Arlington, VA
<PAGE>
 

                     SCHEDULE 4.2 - PHYSICAL ARCHITECTURE
                                
                                [ILLUSTRATIVE]




                             [GRAPH APPEARS HERE]


<PAGE>
 
                     SCHEDULE 4.3 - INITIAL ARCHITECTURE 

                                [ILLUSTRATIVE]


     Bell Atlantic Leases MFS-owned Facilities for Delivery of BA Traffic 
     
                           [FLOOR PLAN APPEARS HERE]
               
               MFS-owned Facilities for Delivery of MFS Traffic
<PAGE>
 
SCHEDULE 4.5

INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC

     Each Party shall provide the other Party with Interconnection to its 
network at the following points for transmission, routing and termination. Each 
Party shall make available at its Interconnection Points facilities to route the
traffic it receives to the appropriate final destination. Interconnection at a 
BA-IP that is a Local Serving Wire Center provides access to all of the 
Interconnection Points identified below (except for paragraphs 8 through 11), 
via facilities appropriate for the traffic types and destinations identified 
below. Compensation for such facilities will be as set forth in Exhibit A or as 
provided elsewhere herein. 
 
     1.   For the termination of Local Traffic or Toll Traffic originated by 
one Party's Customer and terminated to the other Party's Customer, at the points
set forth in subsections 4.2 and/or 4.3 of the main body of the Agreement.

     2.   For the termination of Meet Point Billing Traffic Traffic from an IXC 
to:

          (a)   MFS, at the M-IP in LATA in which the Traffic is to terminate.
     
          (b)   BA, at the BA-IP in LATA in which the Traffic is to terminate.
     
     3.   For the termination of Transit Traffic from an ITC, wireless carrier,
or other CLEC to:

          (a)   MFS, at the M-IP in which the Traffic is to terminate.

          (b)   BA, at the BA-IP in LATA in which the Traffic is to terminate.

     4.   For 911/E911 traffic originated on MFS's network, at the PSAP in areas
where only Basic 911 service is available, or at the BA 911 Tandem Office 
serving the area in which the MFS Customer is located, in accordance with
applicable state laws and regulations and PSAP requirements. 

     5.   For Directory Assistance (411 or NPA-555-1212) traffic, at the 
applicable BA Local Serving Wire Center or the BA operator services Tandem 
Office subtended by such Local Serving Wire Center.

     6.   For Operator Services (call completion) traffic, at the applicable BA
Local Serving Wire Center or the BA operator services Tandem Office subtended by
such Local Serving Wire Center.

     7.   For LSV/VCI traffic, at the terminating Party's Local Serving Wire
Center or operator services Tandem Office subtended by such Local Wire Center.
 
                                      1  
 




<PAGE>
 
     8.   For SS7 signaling originated by:

          (a)  MFS, at mutally agreed-upon Signaling Point of Interconnection(s)
("SPOI") in the LATA in which the Local or Toll Traffic originates, over CCSAC
links provisioned in accordance with Bellcore GR-905 and Bell Atlantic 
Supplement Common Channel Signaling Network Interface Specification (BA_905).

          (b)  BA, at mutually agreed-upon SPOIs in the LATA in which the Local 
or Toll Traffic originates, over a CCSAC links provisioned in accordance with 
Bellcore GR-905 and BA-905.

Alternatively, either Party may elect to interconnect for SS7 signaling through 
a commercial SS7 hub provider.

     9.   For 800/888 database inquiry traffic, at any BA Signaling Transfer 
Point in the LATA in which the originating MFS Wire Center is located, over a 
CCSAC link.  Alternatively, MFS may elect to interconnect through a commercial 
SS7 hub provider.

     10.  For Line Information Database ("LIDB") inquiry traffic, at any BA
Signaling Transfer Point in the LATA in which the LIDB is located, over a CCSAC
link. Alternatively, MFS may elect to interconnect through a commercial SS7 hub
provider.

     11.  For any other type of traffic, at reasonable points to be agreed upon 
by the Parties, based on the network architecture of the terminating Party's
network.

                                       2
<PAGE>
 
SCHEDULE 6.3

RATE ELEMENTS UNDER MEET POINT BILLING

INTERSTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS
- --------------------------------------------------------------------

<TABLE> 
<CAPTION> 
<S>                                     <C>
RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/               
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query
</TABLE> 

INTRASTATE ACCESS - TERMINATING TO OR ORIGINATING FROM MFS CUSTOMERS/1/
- -----------------------------------------------------------------------

<TABLE> 
<CAPTION> 
<S>                                     <C> 
RATE ELEMENT                            BILLING COMPANY
- ------------                            ---------------
Carrier Common Line                     MFS
Local Switching                         MFS
Interconnection Charge                  MFS
Local Transport Facility/               
 Tandem Switched Transport Per Mile     Based on negotiated billing percentage (BIP)
Local Transport Termination/
 Tandem Switched Transport Fixed        BA
Entrance Facility                       BA
800 Database Query                      Party that performs query
</TABLE> 

____________________
/1/  Pending approval of the BA intrastate local transport restructure tariff, 
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

                                       1

<PAGE>
 
SCHEDULE 27.0

PERFORMANCE INTERVAL DATES FOR SPECIFIED ACTIVITIES


- --------------------------------------------------------------------------------
            SPECIFIED ACTIVITY                    PERFORMANCE INTERVAL DATE/2/
 (i)  UNBUNDLED LOCAL LOOP INSTALLATION/1/     
      ---------------------------------
- --------------------------------------------------------------------------------
 1-10 Loops per service order                     6 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 11-20 Loops per service order                    10 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 21 + Loops per service order                     To be negotiated on order-by-
                                                  order basis
- --------------------------------------------------------------------------------
 (ii) INTERIM NUMBER PORTABILITY INSTALLATION     
      ---------------------------------------
- --------------------------------------------------------------------------------
 1-10 Numbers per service order                   6 business days from BA's 
                                                  receipt of valid service order
- --------------------------------------------------------------------------------
 11-20 Numbers per service order                  10 days from BA's receipt of 
                                                  valid service order
- --------------------------------------------------------------------------------
 21 + Numbers per service order                   To be negotiated on 
                                                  order-by-order basis
- --------------------------------------------------------------------------------
 (iii) OUT-OF-SERVICE REPAIRS                     Less than 24 hours from BA's
       ----------------------
                                                  receipt of notification of 
                                                  out-of-service condition
- --------------------------------------------------------------------------------



__________________________
/1/  The Unbundled Loop Installation intervals set forth in this Schedule 27.0 
apply only to ULLs offered by BA as of the date of this Agreement. Installation 
intervals for new ULLs will be developed by the Parties as such ULLs become 
available.
/2/  Unless otherwise agreed to by the Parties, in which case the Performance 
Interval Date shall be extended until the agreed-upon date. Notwithstanding the 
Performance Interval Dates contained in this Schedule 27.0, under no
circumstances will BA be obligated to extend installation, provision, or repair
intervals to MFS that are more favourable than BA extends to its own customers
for comparable services.

                                       2
<PAGE>
 
SCHEDULE 27.1

MFS SERVICE QUALITY STANDARDS


1.0   UNBUNDLED LOCAL LOOP INSTALLATION ORDERS

1.1   All order information submitted by MFS is valid (e.g. street address, 
floor/unit number, cable pair assignment, etc.).

1.2   Customer (end user) is available at appointed time and day.


2.0   "LIVE" CUTOVER UNBUNDLED LOCAL LOOP INSTALLATION ORDERS (PURSUANT TO 
SECTION 11.6)

2.1   Accurate account and end user information submitted on service request.

2.2   Accurate tie cable and pair assignment provided by MFS on service request.

                                       3

<PAGE>
 
                                                                       EXHIBIT A

                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.


                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   ---------------------------------------- 


A.   BA SERVICES, FACILITIES, AND ARRANGEMENTS:

- --------------------------------------------------------------------------------
     BA SERVICE                NON-RECURRING                 RECURRING
     ----------                -------------                 ---------
- --------------------------------------------------------------------------------
1.a. Entrance facilities,      Per interstate [BA FCC #1 sec. 6.9.1.] and 
     and transport, as         (proposed) intrastate [BA-VA SCC 217 sec. 6.8.2] 
     appropriate, for          access tariffs for Feature Group D service/2/
     Interconnection at 
     BA End Office, Tandem
     Office, Serving Wire
     Center, or other Point
     of Interconnection
                               Illustrative:     

                                Interstate non-recurring: $1, plus $1 switched
                               access connection charge per trunk; DS-1 entrance
                               facility $210-212/mo.
          
                                Intrastate nonrecurring: $895 for first DS-1, 
                               $280 for additional, plus $25 switched access 
                               connection charge per trunk; DS-1 entrance
                               facility $270/mo.
- --------------------------------------------------------------------------------
1.b. Collocation and related   Per interstate [BA FCC 1 sec. 19] and intrastate 
     services for              access tariffs/3/
     Interconnection at BA 
     End Office, Tandem 
     Office, or Serving Wire
     Center
- --------------------------------------------------------------------------------



/1/    Rates listed herein for services, facilities, or arrangements that are
marked with an asterisk (*) are fixed pursuant to section 20 of the Agreement
for the initial term of the Agreement, as set forth in Section 22 of the
Agreement. Rates for services, facilities, or arrangements that are not marked
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.

/2/    Pending approval of the BA intrastate local transport restructure tariff,
intrastate access services subject to the pending tariff will be charged 
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at 
either Party's request.

/3/    Pending approval of the BA intrastate collocation tariff to be filed no 
later December 31, 1996, all collocation services shall be charged at rates 
found in BA FCC 1 sec. 19.

                                       1






<PAGE>
 
<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------
      BA SERVICE                      NON-RECURRING         RECURRING
      ----------                      -------------         ---------          
- ----------------------------------------------------------------------------------
<S>   <C>                             <C>                   <C> 
1.C   Tandem transit arrangements     Per tariffs cited in
      (for Interconnection between    sections 1.a. and     Per interstate [BA
      MFS and carriers other than     1.b. above, as        FCC 1 sec. 6.9.1.B]
      BA)                             applicable; separate  and (proposed)
                                      trunks required for   intrastate [BA-VA
                                      IXC subtending        SCC 217 sec. 
                                      trunks/4/             6.8.2.B] for tandem
                                                            switching and tandem
                                                            switched transport,
                                                            as applicable/5/

                                                            
                                                            Illustrative:
                    
                                                             Interstate,
                                                            (proposed)
                                                            intrastate tandem
                                                            switching $.000999/mou, 
                                                            tandem switched 
                                                            transport $.000195/mou 
                                                            plus $.000045/mou/mile
- ----------------------------------------------------------------------------------
1.d.  911 Interconnection             Per tariffs cited in 1.a., 1.b., and 1.c.
                                      above, as applicable, for entrance
                                      facility plus applicable transport, or
                                      Collocation Arrangement at 911 tandem
- ----------------------------------------------------------------------------------
</TABLE> 


/4/  See note 2 above.

/5/  See note 2 above.  
 
                                       2
 
   
                                                           
<PAGE>
 
- --------------------------------------------------------------------------------
       BA SERVICE                  NON-RECURRING            RECURRING
       ----------                  -------------            ---------
- --------------------------------------------------------------------------------
 1.e.  Directory assistance        Intrastate per           Intrastate per
       Interconnection             (proposed) BA-VA         (proposed) BA-VA
                                   SCC 217 sec. 9.6.B       SCC 217 sec. 9.6.B;
                                   (transport)/6/
                                                            Illustrative:

                                                              Per call rate
                                                            $.000092 fixed,
                                                            $.000021 per mile,
                                                            $.000462 tandem
                                                            switching, $.003705
                                                            interconnection/7/

                                   Interstate per BA        Interstate per BA   
                                   FCC 1 sec. 9.6.B         FCC 1 sec. 9.6.B

                                                            Illustrative:

                                                              Per call rate
                                                            $.000082 fixed,
                                                            $.000019 per mile,
                                                            $.000353 tandem
                                                            switching, $.002311
                                                            interconnection
- --------------------------------------------------------------------------------
 1.f.  Operator services (call     Per separate contract
       completion) Interconnection   
- --------------------------------------------------------------------------------
 2.    Unbundled elements          Available as listed herein and in interstate
                                   and intrastate tariffs, and pursuant to 
                                   Section 11. of the Agreement
- --------------------------------------------------------------------------------
 3.    Poles, ducts, conduits,     Per contract rates pursuant to 47 U.S.C. sec.
       ROW                         224

                                   Illustrative:

                                     Duct (Northern Virginia) $4.50/ft/yr.

                                     Pole $4.46/attachment/yr.
- --------------------------------------------------------------------------------

/6/    See note 2 above.

/7/    See note 2 above.

                                       3

<PAGE>
 
<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------
       BA SERVICE                            NON-RECURRING                 RECURRING
       ----------                            -------------                 ---------
- -----------------------------------------------------------------------------------------------------
<S>                                          <C>                           <C> 
4.a.   Local loop transmission*              Permanent rates to be         Permanent rates to be 
                                             determined by                 determined by
        Unbundled Local Loop Element         appropriate arbitral          appropriate arbitral 
                                             body. Interim rates           body. Interim rates   
        Cross Connection to POTS loop        will apply until the          will apply until the  
                                             permanent rates are           permanent rates are   
                                             determined./8/                determined./9/        
                                                                                                 


- -----------------------------------------------------------------------------------------------------
 4.b.  Special construction charges          As applicable per BA-VA SCC 203 sec. 2
- -----------------------------------------------------------------------------------------------------
 4.c   Central office technician charges     Per interstate [BA FCC 1 sec. 13.2 or sec.
       (during normal working hours)         19.5] tariff.

- -----------------------------------------------------------------------------------------------------
 5.a.  Trunk Side local transport

        DS-1 transport                       Per interstate [BA FCC 1 sec. 6.9.1.C] and (proposed)
                                             intrastate [BA-VA SCC 217 sec. 6.8.2.C] tariffs/10/


                                             Illustrative recurring:

                                              Interstate $60/mo. fixed, $17.70/mile/mo.

                                              Intrastate $75/mo. fixed, $30/mile/mo.
- -----------------------------------------------------------------------------------------------------
 5.b.   DS-3 transport                       Tariff reference see 5.a. above.


                                             Illustrative recurring:

                                              Interstate, intrastate $900/mo. fixed,
                                             $180/mile/mo.
- -----------------------------------------------------------------------------------------------------
</TABLE> 

/8/    Interim rates will be based on the following order of precedence: (i)
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in the
state, (iii) any Commission recommendation, or (iv) mutual agreement of the 
Parties.

/9/    See preceding note.

/10/   See note 2 above.

                                       4

<PAGE>
 
<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------
     BA SERVICE                       NON-RECURRING                  RECURRING
     ----------                       -------------                  ---------
- ----------------------------------------------------------------------------------------------
<S>  <C>                              <C>                            <C>  
6.   Local switching*                                                
                                                                     
      POTS switch Port                $6/service order plus          $1.50/mo., plus usage
                                      $6/Port                        per tariff, minus
                                                                     wholesale discount
                                                                     per section 14 below
- ----------------------------------------------------------------------------------------------
7.a. Operator services                                              
                                                               
      911 service (data entry;        No charge                     
     database maintenance)*                                    
- ----------------------------------------------------------------------------------------------
7.b.  Directory assistance            Per tariff or separate         Per tariff or separate
                                      contract; branding             contract
                                      available                     
                                                                     Illustrative tariff rates:
                                                               
                                                                     Interstate [BA FCC 1
                                                                     sec. 9.6], $.275-.288
                                                                     per call
                                                               
                                                                     Intrastate (proposed)
                                                                     [BA-VA SCC 217 sec. 
                                                                     9.6.A], $.25 per call
                                                               
                                                                     Directory transport 
                                                                     per section 1.e. above
- ----------------------------------------------------------------------------------------------
7.c.  Operator call completion        Per separate contract; branding available
- ----------------------------------------------------------------------------------------------
8.a. White pages directory listings*  $5.00 per primary              No charge
                                      listing per number            
- ----------------------------------------------------------------------------------------------
8.b.  Books & delivery (annual home   No charge for normal numbers of books
     area directories only)*          delivered to end users; bulk deliveries to 
                                      CLEC per separate arrangement
- ----------------------------------------------------------------------------------------------
</TABLE> 

                                       5
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                       NON-RECURRING         RECURRING
     ----------                       -------------         ---------
- --------------------------------------------------------------------------------
8.c.   Additional listings, changes   Per tariff [BA-VA     Per tariff [BA-VA
     to listing, non-listed, non-     SCC 203 sec. 4]       SCC 203 sec. 4]
     published, and other extra                           
     services                                             
                                      Illustrative:         Illustrative:

                                       Additional listing:  Additional listing:
                                      $9 residence; $17     $1.12/mo. residence,
                                      business              $1.42/mo. business

                                       Change to listing:   Non-list:
                                      $9 residence; $17     $1.06/mo. residence
                                      business              or business

                                       Non-list:            Non-published:
                                      $9 residence; $17     $1.71/mo. residence
                                      business              or business

                                       Non-published:
                                      $9 residence; $17
                                      business
- --------------------------------------------------------------------------------
9.   Access to telephone numbers
     (NXX codes issued per ICCF
     Code Administrative 
     Guidelines)*                     No charge

- --------------------------------------------------------------------------------
10.a SS7 Interconnection              Per interstate [BA    Per interstate [BA
                                      FCC 1 sec. 6.9.1.G]   FCC 1 sec. 6.9.1.L]
                                      and intrastate [BA-   and intrastate [BA-
                                      VA SCC 217 sec.       VA SCC 217 sec.
                                      6.8.2.C] tariff       6.8.2.G] tariff


                                                            Illustrative:

                                                             STP ports,
                                                            $900/mo.;

                                                             STP access,
                                                            $3.50/mile/mo. to
                                                            $5.72/mile/mo.
- --------------------------------------------------------------------------------

                                       6
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                   NON-RECURRING         RECURRING
     ----------                   -------------         ---------
- --------------------------------------------------------------------------------
10.b LIDB Interconnection         Per tariff [BA FCC 1  Per tariff [BA FCC 1
                                  sec. 6.9.1M]          sec. 6.9.1M]
                                                        
                                  Illustrative:         Illustrative:
                                                        
                                   Originating point     Query validation
                                  code, $125            $.04/query
                                                        
                                                         Query transport
                                                        $.0002/query
- --------------------------------------------------------------------------------
10.c 800/888 data base            No separate charge    Per interstate [BA FCC
     Interconnection              (including in FGD     1 sec. 6.9.2.A.1], and
                                  trunk and STP links)  intrastate [BA-VA SCC
                                                        217 sec. 6.8.2.K]
                                                        tariffs
                                                        
                                                        
                                                        Illustrative:
                                                        
                                                        
                                                         Interstate basic query,
                                                        $.003105/query; vertical
                                                        feature package,
                                                        $.000337/query
                                                        
                                                         Intrastate basic query,
                                                        $.003089/query; vertical
                                                        feature package, 
                                                        $.000327/query
- --------------------------------------------------------------------------------
11.a Interim number portability   service order per     $3/mo. per number
     through co-carrier call      location $30          for up to 10 paths;
     forwarding                                         $.40/mo. per
                                  installation per      additional path
                                  number $35 (unless
                                  installed with
                                  unbundled loop)

                                  installation per
                                  separate path 
                                  arrangement $20
- --------------------------------------------------------------------------------

                                       7
<PAGE>
 
<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------
     BA SERVICE                         NON-RECURRING                RECURRING
     ----------                         -------------                ---------
- ----------------------------------------------------------------------------------------------
<S>  <C>                                <C>                          <C> 
11.b  Access pass-through to number                                  In accordance with 
     portability purchaser*                                          section 14.5 of 
                                                                     Agreement.
- ----------------------------------------------------------------------------------------------
12.  Local dialing parity*              No charge
- ----------------------------------------------------------------------------------------------
13.a Reciprocal call termination

      Local Traffic delivered to Bell
     Atlantic Interconnection Point
     
      First year*                                                    $.009/mou
    ------------------------------------------------------------------------------------------
      After first year*                                              In accordance with note
                                                                     13 below
- ----------------------------------------------------------------------------------------------
13.b  Access charges for termination                                 Per interstate and 
     of intrastate and interstate                                    intrastate access 
     Toll Traffic                                                    tariffs (charged in
                                                                     conjunction with Local
                                                                     Traffic, using PLU and 
                                                                     PIU, as appropriate)
- ----------------------------------------------------------------------------------------------
14.a Wholesale rates for resale of      Percentage discount from retail tariff/12/ 
                                        ------------------------------------------
     telecommunications services      
     provided to end users*/11/
- ----------------------------------------------------------------------------------------------
14.b  Individual Case Basis services    No discount
     and similar single-customer
     serving arrangements; directory
     assistance and operator call
     completion*
- ----------------------------------------------------------------------------------------------
</TABLE> 


/11/      Excludes telecommunications services designed primarily for wholesale,
such as switched and special access, and, subject to Section 12 of the
Agreement, the following additional arrangements that are not subject to resale:
limited duration promotional offerings, public coin telephone service, and
technical and market trials. Taxes shall be collected and remitted by the
reseller and BA in accordance with legal requirements and as agreed between the
Parties. Surcharges (e.g., 911, telecommunications relay service, universal
service fund) shall be collected by the reseller and either remitted to the
recipient agency or NECA, or passed through to BA for remittance to the
recipient agency or NECA, as appropriate and agreed between the Parties. End
user common line charges shall be collected by the reseller and remitted to BA.

/12/      Pending establishment of mechanized billing procedures adapted to
resale, the Parties will agree upon a composite "bottom-of-the-bill" discount
that reflects the discounts and exclusions identified herein, and such other
adjustments as the Parties agree.

                                       8
<PAGE>
 
<TABLE> 
<CAPTION>  
- -----------------------------------------------------------------------------------------------
          BA SERVICE                            NON-RECURRING               RECURRING         
          ----------                            -------------               ---------         
- ------------------------------------------------------------------------------------------------
<S>      <C>                                    <C>                         
 14.c      IntraLATA toll, including            Discount per sections 14.d. and 14.e. below   
          discount plans*                       applied to composite weighted average toll    
                                                rate per minute                               
- ------------------------------------------------------------------------------------------------
 14.d      Other retail residential services*   6% discount                                   
- ------------------------------------------------------------------------------------------------
 14.e      Other retail business services*      9% discount                                   
- ------------------------------------------------------------------------------------------------
</TABLE> 

                                       9

<PAGE>
 
<TABLE> 
<CAPTION>  
            B.    MFS SERVICES, FACILITIES, AND ARRANGEMENTS: 
          ----------------------------------------------------------------------------------------------------------------
                   MFS SERVICE                            NON-RECURRING               RECURRING   
                   -----------                            -------------               --------- 
          ----------------------------------------------------------------------------------------------------------------
          <S>      <C>                                    <C>                         <C>  
           1.a.    Interim Number Portability                                                          
                   through co-carrier call                                                             
                   forwarding*                                                                         

                    Number portability*                   $30/service order,          $3/mo. for ten paths
                                                          $35/number (not             per number; plus
                                                          ordered with ULL)           $.40/mo. per
                                                                                      additional path
                                                          $20 per additional
                                                          path order
          ----------------------------------------------------------------------------------------------------------------
           1.b      Access pass-though to number                                      In accordance with
                   portability purchaser*                                             sec. 14.5 of
                                                                                      Agreement
          ----------------------------------------------------------------------------------------------------------------
           2.      Local dialing parity*                  No charge
          ----------------------------------------------------------------------------------------------------------------
           3.a     Reciprocal call termination

                    Local Traffic delivered to MFS
                   Interconnection Point*

                    First year*                                                       $.009/mou
                   ---------------------------------------------------------------------------------------------------------
                    After first year*                                                 In accordance with
                                                                                      note 13 below
          ------------------------------------------------------------------------------------------------------------------
           3.b      Access charges for termination                                    Per MFS interstate
                   of intrastate and interstate Toll                                  and intrastate access
                   Traffic                                                            rates (charged in conjunction
                                                                                      with Local Traffic, using PLU
                                                                                      and PIU, as appropriate)
          ------------------------------------------------------------------------------------------------------------------
           4.      All other MFS services available       Available at MFS tariffed or otherwise         
                   to BA for purposes of                  generally available rates, not to exceed BA 
                   effectuating local exchange            rates for equivalent services available to MFS
                   competition
          ------------------------------------------------------------------------------------------------------------------
           5.       Other Services

                   Information Service billing fee        No Charge                   $.03 per call 
          ------------------------------------------------------------------------------------------------------------------
</TABLE> 

                                      10

<PAGE>
 
13   LOCAL TRAFFIC TERMINATION RATES (AFTER FIRST YEAR)

A.   Charges by BA
     -------------

     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA 
          Access Tandem: $.009 per mou

     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou

     Note: All BA-IPs identified in Schedule 4.0 as of the Effective Date are
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs
     shall be subject to the rate of $.009 per mou.

B.   Charges by MFS
     --------------

1.   Single-tiered interconnection structure:

     MFS's rates for the termination of BA's Local Traffic under the single-
     tiered interconnection structure shall be recalculated once each year on
     each anniversary of the Effective Date (the "Rate Determination Date"). The
     initial Rate Determination Date shall be the first anniversary of the
     Effective Date. The methodology for recalculating the rates is as follows:

          LSWC/Access Tandem Minutes = Total minutes of use of Local Traffic
          delivered by MFS to the BA LSWC or BA Access Tandem for most recent
          billed month.

          End Office Minutes = Total minutes of use Local Traffic delivered by
          MFS directly to the terminating BA End Office for most recent billed
          month.

          Total Minutes = Total minutes of use of Local Traffic delivered by MFS
          to BA for most recent billed month.

          MFS Charge at the M-IP =

          (LSWC/Access Tandem Minutes x $.009) + (End Office Minutes x $.007)
          -------------------------------------------------------------------
                                 Total Minutes


2.   Multiple-tiered interconnection structure (if offered by MFS to any
     carrier)

     (a)  Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009

     (b)  Local Traffic delivered to terminating MFS End Office/node: $.007

                                      11
<PAGE>
 
C.   Miscellaneous Notes
     -------------------

1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended, and/
or (ii) where the Tandem Office that it subtends is not located within 25 miles
of the Tandem Office that is subtended by the terminating End Office, then such
Party shall (x) in addition to paying the LSWC/Access Tandem termination rate
described above, purchase the necessary facilities from the terminating Party to
transport such traffic to a qualifying LSWC or Access Tandem that is not subject
to either conditions (i) or (ii) above, (y) purchase such other service(s) as
the terminating Party may offer under applicable tariff to remedy such
condition(s), or (z) enter into a new compensation arrangement as the Parties
may agree. Notwithstanding the foregoing, nothing in this Agreement shall
obligate BA to provide switching services at a LSWC when it functions as such.

2.   In the event the two-tiered rate structure described above is modified 
pursuant to Applicable Law to a single rate structure, BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting 
Local Traffic it receives at its LSWC to the first point of switching in its 
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure 
set forth above is intended by the Parties to be a Local Traffic termination 
rate for Interconnection to the M-IP within each LATA that is reciprocal and 
equal to the actual rates that will be charged by BA to MFS under the 
two-tiered Local Traffic termination rate structure described above that will 
apply after the first anniversary of the Effective Date. The single MFS 
termination rate is also intended to provide financial incentives to MFS to 
deliver traffic directly to BA's terminating End Offices once MFS's traffic 
volumes reach an appropriate threshold. The Parties agree that the Reciprocal 
Compensation rate(s) set forth herein recover a reasonable approximation of each
Party's additional costs of terminating calls that originate on the network 
facilities of the other Party.

                                      12
<PAGE>
 
EXHIBIT B

                       NETWORK ELEMENT BONA FIDE REQUEST


     1.  Each Party shall promptly consider and analyze access to a new
unbundled Network Element with the submission of a Network Element Bona Fide
Request hereunder. The Network Element Bona Fide Request process set forth
herein does not apply to those services requested pursuant to Report & Order and
Notice of Proposed Rulemaking 91-141 (rel. October 19, 1992), Paragraph 259 and
Footnote 603 or subsequent orders.

     2.  A Network Element Bona Fide Request shall be submitted in writing and
shall include a technical description of each requested Network Element, the
telecommunications service(s) to be provided by the requesting Party using the
requested Network Element(s), the means of Interconnection, the number or volume
requested, the locations, and the date(s) such Network Elements are desired. The
requesting Party shall either make a binding commitment to order the Network
Elements requested in the quantity and within the time frame requested or to pay
the requested Party the costs of processing the Requests.

     3.  The requesting Party may cancel a Network Element Bona Fide Request at
any time, but shall pay the other Party's reasonable and demonstrable costs of
processing and/or implementing the Network Element Bona Fide Request up to the
date of cancellation.

     4.  Within ten (10) business days of its receipt, the receiving Party shall
acknowledge receipt of the Network Element Bona Fide Request.

     5.  Except under extraordinary circumstances, within thirty (30) days of
its receipt of a Network Element Bona Fide Request, the receiving Party shall
provide to the requesting Party a preliminary analysis of such Network Element
Bona Fide Request. The preliminary analysis shall confirm that the receiving
Party will offer access to the Network Element or will provide a detailed
explanation that access to the Network Element is not technically feasible
and/or that the request does not qualify as a Network Element that is required
to be provided under the Act.

     6.  If the receiving Party determines that the Network Element Bona Fide
Request is technically feasible and otherwise qualifies under the Act, it shall
promptly proceed with developing the requested Network Element upon receipt of
written authorization from the requesting Party. When it receives such
authorization, the receiving Party shall promptly develop the requested
services, determine their availability, calculate the applicable prices and
establish installation intervals.

     7.  Unless the Parties otherwise agree, the requested Network Element must
be priced in accordance with Section 252(d)(l) of the Act.

                                       1
<PAGE>
 
     8.  As soon as feasible, but not more than ninety (90) days after its
receipt of authorization to proceed with developing the requested Network
Element, the receiving Party shall provide to the requesting Party a Network
Element Bona Fide Request quote which will include, at a minimum, a description
of each Network Element, the availability, the applicable rates and the
installation intervals.

     9.  Within thirty (30) days of its receipt of the Network Element Bona Fide
Request quote, the requesting Party must either confirm its order for the
requested Network Element pursuant to the Network Element Bona Fide Request
quote or seek arbitration by the Commission pursuant to Section 252 of the Act.

     10.  If a Party to a Network Element Bona Fide Request believes that the
other Party is not requesting, negotiating or processing the Network Element
Bona Fide Request in good faith, or disputes a determination, or price or cost
quote, or is failing to act in accordance with section 251 of the Act, such
Party may seek mediation or arbitration by the Commission pursuant to Section
252 of the Act.

                                       2
<PAGE>
 
EXHIBIT C

                   DIRECTORY ASSISTANCE AND CALL COMPLETION
                              SERVICES AGREEMENT


     THIS AGREEMENT is made, effective this ________ day of _________,1996,
by and between BELL ATLANTIC NETWORK SERVICES, INC. (hereinafter referred to 
as "Bell Atlantic"), a Delaware corporation with offices at 13100 Columbia 
Pike, Silver Spring, MD 20904, and ________________, (hereinafter referred to 
as "Carrier"), a ______________ corporation with offices at _________________
_______________________.


1.   SCOPE AND TERM OF AGREEMENT
     ---------------------------

1.1  SCOPE This Agreement sets forth the terms and conditions which shall govern
the use of payment for Directory Assistance (DA) Service and  IntraLATA Call 
Completion Service (hereinafter collectively referred to as "Services") to be 
provided by Bell Atlantic, or its affiliated companies, to Carrier. Carrier 
shall subscribe to and pay for Services for Carrier's local exchange customers
in the _____________ LATAs.

1.2  TERM The initial term of this Agreement shall commence as of 12:01 a.m. on
the date first written above and shall expire upon the conclusion of the 
subscription period selected by Carrier in Appendix A. At the end of this 
initial term, this Agreement, including Carrier's subscription to Services, 
shall automatically renew for the same length of time as the initial 
subscription period unless either party provides written notice to the other of
its intent to terminate at least three (3) months prior to the expiration of 
the current term.

2.   DESCRIPTION OF SERVICES
     -----------------------

2.1  DIRECTORY ASSISTANCE (DA) SERVICE

     a. Directory Assistance Service shall consist of 1) directory transport by
Bell Atlantic from the point of Bell Atlantic's interconnection with Carrier's
trunks to Bell Atlantic's designated DA locations, and 2) the provision of
telephone number listings by Bell Atlantic Carrier Call Representatives (CCRs)
in response to calls from Carrier's local exchange customers located in the
LATAs designated in Section 1.1, at the rates specified in Appendix A.   

                                       1
 
        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
     b.   A maximum of two requests for telephone numbers will be accepted per 
DA call. A "DA call" as used in this Agreement shall mean a call answered by or 
forwarded to Bell Atlantic, regardless of whether a telephone number is 
requested, provided or available. The listings that will be available to 
Carrier's customers are those telephone numbers that are listed in Bell 
Atlantic's DA records for the LATAs or NPAs designated in Section 1.1.

2.2  CONNECT REQUEST(SM) SERVICE

     a)   Connect ReQuest(SM) Service is an optional DA call completion service.
It provides Directory Assistance end users the option of placing a call to a
requested DA listing without having to hang up and redial. If a caller requests
two numbers on a DA call, only the second number will be completed using
Connect ReQuest(SM).

     b)   Connect ReQuest(SM) requires that the Carrier meet switching,
facility, and other technical standards as required by Bell Atlantic to provide
this Service. Bell Atlantic will deliver all Connect ReQuest(SM) calls back to
the Carrier for completion.

2.3  INTRALATA CALL COMPLETION SERVICE

     a)   IntraLATA Call Completion Service consists of the live and automated 
call completion services specified in Appendix B, including the completion of 
collect, card and bill-to-third party calls; busy line verification; customer 
requested interrupt; and other assistance to callers. IntraLATA Call Completion 
Service includes the support of the Bell Atlantic carrier call centers and call 
completion facilities used to provide such services to Carrier.

     b)   Bell Atlantic will provide Carrier with unrated records for the call 
completion services provided by Bell Atlantic on behalf of Carrier. The rating, 
billing, and settlement of end-user charges for the calls are the responsibility
of Carrier.

2.4  BRANDING   Branding is a service option that permits the Carrier to deliver
a customized front end announcement to its callers, identifying the Carrier as
the customer service provider. Branding is available for DA as well as Call
Completion Services. Carrier shall provide the information required by Bell
Atlantic to create this announcement. Branding also requires that the Carrier
maintain dedicated trunking arrangements to the designated Bell Atlantic DA or
operator switch location.

2.5  CARRIER SUBSCRIPTION SELECTION FORM   The specific Services to which
Carrier shall subscribe and the applicable service subscription periods are
contained in Appendix A ("Carrier Subscription Selection Form").

3.   COMMENCEMENT AND IMPLEMENTATION OF SERVICE
     ------------------------------------------

                                       2

        This information is Bell Altantic Proprietary and Confidential
<PAGE>
 
3.1  TECHNICAL QUESTIONNAIRE  Each party shall make good-faith efforts to carry 
out its respective responsibilities in meeting a jointly established schedule 
for implementation. All records and other required information specified in 
Appendix C will be furnished by Carrier at least sixty (60) days prior to the 
commencement of Services (i.e., the cutover date described in Section 3.2.) 
Notices of any changes, additions, or deletions to such records and information 
shall be provided promptly in writing by Carrier to Bell Atlantic.

3.2  CUTOVER  The cutover date for a selected Services shall be the date on 
which such Service shall be available to all of Carrier's local exchange 
customers in the LATAs designated in Section 1.1.  The subscription term set 
forth in Appendix A for such Services shall commence on the cutover date.

3.3  SERVICE REVIEW MEETINGS  Bell Atlantic will meet and confer with Carrier 
during the term of this Agreement to review and discuss the Services provided 
under this Agreement. The times for meetings will be established by mutual 
agreement of the parties.


4.   EQUIPMENT AND FACILITIES
     ------------------------

4.1  BELL ATLANTIC  will establish and maintain such access equipment and
related facilities for its Carrier Call Centers as may be necessary to perform
the Services specified in Appendix A, provided that Carrier furnishes Bell
Atlantic the information specified in Appendix C and any changes in such
information in a timely and accurate manner. Any additional Services that
Carrier seeks during the term of this Agreement will be subject to mutual
agreement and the availability of facilities and equipment.

4.2  CARRIER  will provide and maintain such equipment within its premises as is
necessary to permit the Bell Atlantic to perform the agreed upon Services in
accordance with Bell Atlantic standard equipment operation and traffic operation
procedures.

4.3  CARRIER TRANSPORT AND SWITCHED ACCESS CONNECTION

     a)   Carrier shall, at its expense, arrange for and establish the trunking 
and other transport, interface, and signaling arrangements required for Bell 
Atlantic to provide Services to Carrier. Separate dedicated trunks for each NPA 
or LATA may be required. Any trunks or other transport and access that Carrier 
obtains from Bell Atlantic to deliver Carrier's call to Bell Atlantic shall be 
provided pursuant to the applicable tariffs, and not under this Agreement. Bell 
Atlantic agrees to coordinate the scheduling of Services to be provided under 
this Agreement with the scheduling of any trunking or related services, 
provisioned by Bell Atlantic under the tariffs.

                                       3

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
     b)   Carrier shall specify the number of trunks required for Services. For 
Directory Assistance Service, Carrier must provide Feature Group D (FGD) trunks 
directly to the location designated by Bell Atlantic. For IntraLATA Call 
Completion Service, Carrier must provide trunks with operator services signaling
directly to the location designated by Bell Atlantic. Bell Atlantic shall 
provide Carrier at least three (3) months advance notice in the event of any 
change in designated locations.

5.   PAYMENT FOR SERVICES
     --------------------

5.1  RATES  Carrier agrees to pay for Services at the rates contained in 
Appendix A.

5.2  SETTLEMENTS  Carrier shall render payment to Bell Atlantic net thirty (30) 
calendar days from the date of delivery of the Service or from the date of 
billing for the Service, whichever occurs later. Carrier shall pay interest on 
any amount overdue at the rate of fifteen (15) percent per annum.

5.3  TAXES  The rates specified in this Agreement and Appendices are exclusive 
of all taxes, duties or similar charges imposed by law. Carrier shall be liable 
for and shall reimburse Bell Atlantic for any sales, use, excise or other taxes 
applicable to the services performed under this Agreement.

5.4  LIQUIDATED DAMAGES  In the event that Carrier discontinues using Bell 
Atlantic's Services in whole or in part, or terminates this agreement prior to 
the expiration of the subscription term, the parties agree that Bell Atlantic   
will incur expenses and damages that will be difficult to calculate. Therefore, 
the parties agree that in the event of such discontinuance or termination, 
Carrier shall pay an amount equal to the charges billed for the month in which 
the highest usage of Services occurred, multiplied by the number of months 
remaining in the then-current term, or b) the sum of $100,000, whichever is 
greater. If Carrier causes this Agreement to terminate before the commencement 
of any Service selected in Appendix A, Carrier shall pay for all costs already 
incurred by Bell Atlantic in establishing and preparing for the commencement of 
such Service or the sum of $100,000, whichever is greater.

5.5  CARRIER'S CUSTOMERS  Carrier shall be responsible for all contacts and 
arrangements with its customers concerning the provision and maintenance, and 
the billing and collection, of charges for Services furnished to Carrier's 
customers.

6.   LIMITATION OF LIABILITY
     -----------------------

6.1  DIRECT DAMAGES  In the event that Bell Atlantic, through negligence or 
willful misconduct, fails to provide the Services selected and contracted for 
under this Agreement, Bell Atlantic shall be liable to Carrier for Carrier's 
direct damages resulting from such failure, up to an amount not to exceed the 
payment of charges under this Agreement for the Services affected.


                                       4

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
6.2   OTHER REMEDIES   THE EXTENT OF BELL ATLANTIC'S LIABILITY ARISING UNDER
THIS AGREEMENT SHALL BE LIMITED AS DESCRIBED IN PARAGRAPH 6.1 ABOVE. IN NO EVENT
SHALL BELL ATLANTIC BE LIABLE FOR ANY OTHER LOSS, COST, CLAIM, INJURY,
LIABILITY, OR EXPENSE RELATED TO OR ARISING OUT OF THIS AGREEMENT OR THE
SERVICES PROVIDED HEREUNDER INCLUDING, BUT NOT LIMITED TO, ANY INCIDENTAL,
SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS
OF REVENUE OR PROFIT, WHETHER RECOVERY IS SOUGHT IN TORT, CONTRACT, OR
OTHERWISE, EVEN IF BELL ATLANTIC HAD NOTICE OF SUCH DAMAGES.


7.   DEFAULTS AND TERMINATION
     ------------------------ 

7.1  DEFAULTS OR VIOLATIONS  If Carrier defaults in the payment of any amount 
due hereunder, or if Bell Atlantic fails to provide Services as agreed 
hereunder, and such default or failure shall continue for thirty (30) days after
written notice thereof, the other company may terminate this agreement with (7) 
days written notice.

8.   CONFIDENTIAL INFORMATION
     ------------------------

8.1  CONFIDENTIALITY  The parties agree that all confidential and proprietary 
information that is marked as specified in Section 8.2 and that is disclosed by 
either party to the other party for the purposes of this Agreement, including 
rates and terms, shall be treated as confidential unless a) such information was
previously or becomes known to the receiving party free of any obligation to 
keep it confidential, b) has been or is subsequently made public by the 
disclosing party, or c) is required to be disclosed by law. The receiving party 
shall not, except in the performance of the Services under this Agreement or 
with the express prior written consent of the other party, disclose or permit 
access to any confidential information to any other parties. The parties agree 
to advise their respective employees, agents and representatives to take such 
action as may be advisable to preserve and protect the confidentiality of such 
information.

8.2  MARKETING OF CONFIDENTIAL INFORMATION  All information the disclosing party
considers proprietary or confidential, if in writing or other tangible form, 
shall be conspicuously labeled or marked as "Proprietary" or "Confidential" and,
if oral, shall be identified as proprietary at the time of disclosure and 
promptly confirmed in writing. Either party shall have the right to correct any 
inadvertent failure to designate information as proprietary by written 
notification within ten (10) days following disclosure.


9.   RELATIONSHIP OF THE PARTIES
     ---------------------------

9.1  INDEPENDENT CONTRACTORS   Bell Atlantic and Carrier shall be independent 
contractors under this Agreement and all services under this Agreement shall be 
performed by Bell Atlantic as an independent contractor and not as an agent of 
Carrier.

                                       5

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
9.2  RESPONSIBILITY FOR EMPLOYEES AND AGENTS   All persons furnished by Bell 
Atlantic shall be considered solely Bell Atlantic's employees or agents, and 
Bell Atlantic shall be responsible for compliance with all laws, rules, and 
regulations relating to such persons including, but not limited to, hours of 
labor, working conditions, workers' compensation, payment of wages, benefits, 
unemployment, social security and other payroll taxes. Each party's employees 
and agents, while on premises of the other, shall comply with all rules and 
regulations, including any applicable security procedures and safeguarding of 
confidential data.

10.  GENERAL CONDITIONS
     ------------------

10.1 ASSIGNMENT  Neither party may assign or delegate its rights and obligations
under this Agreement without the prior written consent of the other party except
that Bell Atlantic may assign this Agreement to an affiliate or subsidiary
without such consent.

10.2 CHOICE OF LAW  The validity, construction and performance of this Agreement
shall be governed by the laws of ____________________.

10.3 COMPLIANCE WITH LAWS  Each party shall comply with all applicable federal,
state, county and local laws, ordinances, regulation, rules and codes in the 
performance of this Agreement. Neither party shall be liable to the other for 
termination of this Agreement or any services to be provided hereunder 
necessitated by compliance with any law, rule, regulation or court order of a 
duly authorized governmental body.

10.4 CONTINGENCY  Neither party shall be held responsible or liable to the other
for any delay or failure in performance caused by fires, strikes, embargoes, 
requirements imposed by Government regulation, civil or military authorities, 
act of God or by the public enemy, or other causes beyond the control of Carrier
or Bell Atlantic. If such a contingency occurs, the party injured by the other's
inability to perform may: a) terminate the affected services or part thereof not
already rendered; or b) suspend the affected services or part thereof for the 
duration of the delaying cause and resume performance once the delaying causes 
cease.

10.5 LICENSES  No licenses, expressed or implied, under any patents, copyrights,
trademarks or other intellectual property rights are granted by Bell Atlantic to
Carrier under this Agreement.

10.6 NOTICES  Except as otherwise specified in this Agreement, any notice 
required or permitted under this Agreement shall be in writing and shall be 
given to the other party at the address designated below by hand delivery, 
registered return-receipt requested mail, confirmed facsimile, or nationally 
recognized courier service;

                                       6

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
               For Bell Atlantic:  Bell Atlantic Network Services, Inc.
                                   13100 Columbia Pike, D39
                                   Silver Spring, MD 20904
                                   Attn:___________, Product Manager

               For Carrier:


The above addresses may be changed by giving thirty (30) calendar days prior 
written notice as prescribed above. Notice shall be deemed to have been given or
made on the date of delivery if received by hand, facsimile or express courier, 
and three days after delivery to the U.S. Postal Service, if mailed.

10.7   PUBLICITY  Bell Atlantic and Carrier agree to submit to each other prior
to publication all advertising, sales promotions, press releases and other
publicity matters containing or mentioning a) the services performed by Bell
Atlantic under this Agreement, b) either party's name or marks, or c) language
from which either Party's names or marks may be inferred or implied. Bell
Atlantic and Carrier further agree not to publish or use any such advertising,
sales promotion, press releases, or publicity matters unless it obtains the
other party's prior written consent.

10.8   SEVERABILITY  If any provision of this Agreement or the application of
any provision shall be held by a tribunal of competent jurisdiction to be
contrary to law or unenforceable, the remaining provisions of this Agreement
shall continue in full force and effect.

10.9   SURVIVAL  All obligations hereunder, incurred by either Bell Atlantic or 
Carrier prior to the cancellation, termination or expiration of this Agreement 
shall survive such cancellation, termination or expiration.

10.10  CAPTIONS AND SECTION HEADINGS  The captions and section headings in this 
Agreement are for convenience only and do not affect the meaning or 
interpretation of this Agreement.

10.11  DUPLICATE ORIGINALS  This Agreement may be executed separately by the 
parties in one or more counterparts. Each duplicate executed shall be deemed an 
original, and all together shall constitute one and the same document.

10.12  NONDISCLOSURE OF AGREEMENT  Each party agrees not to disclose the terms 
and conditions of this Agreement to any third party, except that it shall not be
deemed a breach of this provision for the parties to disclose the terms and 
conditions of this

                                       7

<PAGE>
 
Agreement to their respective subsidiaries and affiliated companies or to any 
duly constituted governmental body which requires disclosure.

10.13 ENTIRE AGREEMENT  The terms and conditions of this Agreement, including 
Appendices A, B, and C attached to this Agreement, constitute the entire 
Agreement between Bell Atlantic and Carrier relating to the subject matter of 
this Agreement, and supersede any and all prior or contemporaneous 
understandings, promises or representations, whether written or oral, between 
the parties relating to the subject matter of this Agreement. Any waiver, 
modification or amendment of any provision of this Agreement, or of any right or
remedy hereunder, shall not be effective unless made in writing and signed by 
both parties.

IN WITNESS WHEREOF, the parities agree that the effective date of this 
Agreement is the date first written above, and each party warrants that it has 
caused this Agreement to be signed and delivered by its duly authorized 
representative.


BELL ATLANTIC
NETWORK SERVICES, INC.


NAME:__________________________         NAME:____________________________

TITLE:_________________________         TITLE:___________________________

SIGNATURE:_____________________         SIGNATURE:_______________________

DATE:__________________________         DATE:____________________________

                                       8

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
                                                                      APPENDIX A

                     CARRIER SUBSCRIPTION SELECTION FORM
                     -----------------------------------

- --------------------------------------------------------------------------------
 CONTRACT DA SERVICE                      SUBSCRIPTION         RATE PER
 SELECTED                                 PERIOD               CALL
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - STANDARD                YEAR(S)                
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - STANDARD WITH 
 FRONT END BRANDING*                            YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE           YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE - LIVE RESPONSE
 WITH FRONT END BRANDING*                       YEAR(S)
- --------------------------------------------------------------------------------
 DIRECTORY ASSISTANCE CALL COMPLETION           YEAR(S)
- --------------------------------------------------------------------------------
 INTRALATA CALL COMPLETION                      YEAR(S)        SEE RATES BELOW 
- --------------------------------------------------------------------------------
 BRANDED INTRALATA CALL COMPLETION*             YEAR(S)        SEE RATES BELOW
- --------------------------------------------------------------------------------
 * PLUS NONRECURRING BRANDING FEE OF $ _________.

 For informational purposes, the following are the charges for Directory 
 Transport to be provided under the applicable tariffs. (Call miles are measured
 from the BA Wire Center serving Carrier's premises to the DA location):

     Call Miles                                    Rate Per Call
     ----------                                    -------------
     0 to 1 mile ............................... $ 0.0014
     * 1 to 4 miles ............................   0.0015
     * 4 to 8 miles ............................   0.0016
     * 8 to 16 miles ...........................   0.0018
     * 16 to 25 miles ..........................   0.0018
     * 25 to 50 miles ..........................   0.0019
     * 50 to 200 miles .........................   0.0020

- --------------------------------------------------------------------------------
                             CALL COMPLETION RATES
- --------------------------------------------------------------------------------
 TOTAL ANNUAL CALL VOLUME    AUTO       AUTO COLLECT/      LIVE CCR HANDLED
 (ALL CALLS)                PER CALL    THIRD (PER CALL)   PER CCR WORK SECOND
- --------------------------------------------------------------------------------
 0 - 20,000          
- --------------------------------------------------------------------------------
 20,001 - 100,000
- --------------------------------------------------------------------------------
 100,001 +
- --------------------------------------------------------------------------------
 Notes: 1) Trunking and switched access costs are not included in the above DA 
 ------    
           and Call Completion rates.

        2) Rates for automated IntraLATA Call Completion calls are based on call
           attempts.

*  Greater Than

_________________________________                 ______________________________
SIGNATURE (BELL ATLANTIC)                         SIGNATURE (CARRIER)

                                       9

        This information is Bell Atlantic Proprietary and Confidential
<PAGE>
 
                           BELL ATLANTIC RATE SHEET

             VIRGINIA LOCAL EXCHANGE CARRIER DIRECTORY ASSISTANCE


   DIRECTORY ASSISTANCE CALL CHARGE (PER CALL, BASED ON LENGTH OF CONTRACT)

 Type of Service                     Month-to Month        1-year      3-year
 ---------------                    ----------------      --------    --------

- --------------------------------------------------------------------------------
 Standard                           $.275             $.25          $.23
- --------------------------------------------------------------------------------
 Standard w/Customized Branding*     .278              .253          .233
- --------------------------------------------------------------------------------
 Live Carrier Call Representative 
 (CCR)                               .285              .26           .24   
- --------------------------------------------------------------------------------
 Live CCR w/Customized Branding*     .288              .263          .243
- --------------------------------------------------------------------------------

 * Customized branding fee (non-recurring charge): $6,000


       CONNECT REQUEST(TM) DIRECTORY ASSISTANCE CALL COMPLETION (OPTIONAL)

- --------------------------------------------------------------------------------
 Charge per Request (in addition 
 to above charges)                  $.27              $.25          $.22
- --------------------------------------------------------------------------------



                          DIRECTORY TRANSPORT CHARGE

 (For each call to Directory Assistance service; call miles measured from the 
 wire center serving the customer's premises to the DA location).

     Call Miles                                 Rate Per Call
     ----------                                 -------------

     0 to 8 ................................. $ 0.0037
     * 8 to 13 ..............................   0.0062
     * 13 to 18 .............................   0.0076
     * 18 to 23 .............................   0.0089
     * 23 to 28 .............................   0.0137
     * 28 miles .............................   0.0223


 Trunk installation charges are not included.
 
*  Greater than
 
<PAGE>
 
                                                         [LOGO OF BELL ATLANTIC]

<TABLE> 
<CAPTION> 
                                                      PROPOSED PRICING TERMS

                                                INTRALATA CALL COMPLETION SERVICES

                                                COMPETITIVE LOCAL EXCHANGE CARRIERS

                                                  (Prices effective June 1, 1996)

- ---------------------------------------------------------------------------------------------------------------------------------- 
                            TWO YEAR TERM                       THREE YEAR TERM                        FIVE YEAR TERM
- ---------------------------------------------------------------------------------------------------------------------------------- 
TOTAL ANNUAL        Auto        Auto        Operator      Auto        Auto        Operator      Auto        Auto        Operator  
CALL VOLUME         Card        Collect/    Handled       Card        Collect/    Handled       Card        Collect/    Handled
(all calls)         (per call)  Third       (per OWS)     (per call)  Third       (per OWS)     (per call)  Third       (per OWS)  
                                (per call)                            (per call)                            (per call)  
- ---------------------------------------------------------------------------------------------------------------------------------- 
<S>                 <C>         <C>         <C>           <C>         <C>         <C>           <C>         <C>         <C> 
0 - 20,000           $0.15       $0.20       $0.0145       $0.14       $0.19       $0.0141       $0.13       $0.18       $0.0136
- ---------------------------------------------------------------------------------------------------------------------------------- 
20,001 - 100,000     $0.14       $0.19       $0.0141       $0.13       $0.18       $0.0136       $0.12       $0.17       $0.0131
- ---------------------------------------------------------------------------------------------------------------------------------- 
100,000 +            $0.13       $0.18       $0.0136       $0.12       $0.17       $0.0131       $0.11       $0.16       $0.0126
- ---------------------------------------------------------------------------------------------------------------------------------- 
</TABLE> 


Notes:    Trunking costs are not included in the above rates.
          The rates quoted above for automated calls are based on call attempts.
          All prices include company specific branding.



                            PROPRIETARY INFORMATION
                NOT FOR USE OR DISCLOSURE OUTSIDE BELL ATLANTIC
                        EXCEPT UNDER WRITTEN AGREEMENT.

<PAGE>

                                                                      APPENDIX B
 
                      INTRALATA CALL COMPLETION SERVICES
                      ----------------------------------
A.   Calling Card
     ------------
     Bell Atlantic Carrier Call Representative keys the calling card number and 
     call details into the system, secures validation, and releases the call 
     into the network.

B.   Collect
     -------
     Bell Atlantic Carrier Call Representative obtains the calling party's name,
     keys the call details if necessary, announces the call to the called party,
     waits for acceptance, and releases the call into the network.

C.   Billed To A Third Party
     -----------------------   
     Bell Atlantic Carrier Call Representative requests the calling party's 
     name, keys the call details if necessary, calls the third party to verify
     acceptance of billing, and releases the call once acceptance is given.

D.   Assistance - Other
     ------------------
     Bell Atlantic Carrier Call Representative will dial a called number for the
     customer for any of the following reasons:

     1. Customer encounters trouble such as wrong number, poor transmission or
     cutoff, and requests a credit or reconnection.

     2. Customer desires time and charges at the end of conversation.

     3. Customer requires dialing assistance due to a disability.

     4. Customer is unwilling to dial call.

E.   Person-to-Person
     ----------------
     Bell Atlantic Carrier Call Representative requests the person or department
     the calling party has specified, ensures appropriate party has been reached
     (person or department), and releases call.

F.   Busy-Line Verification
     ----------------------
     Bell Atlantic Carrier Call Representative determines if the number
     specified by the customer is in use, idle, or out of order.

G.   Customer-Requested Interrupt
     ----------------------------

                                      10

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
     At the customer's request, Bell Atlantic Carrier Call Representative will 
     interrupt conversation in progress on a line that has been verified in use.
                                                             APPENDIX B (CONT'D)

H.   Assistance (0-)
     ---------------
     Bell Atlantic Carrier Call Representative will provide customer dialing
     instructions, assistance with emergency calls, area code information, and
     business office or repair service.

I.   Validation Services
     -------------------
     Bell Atlantic will launch a query for the validation of all calling card
     calls, collect calls, billed-to-third number calls and public telephone
     checks to a Line Information Data Base (LIDB). The query costs for query of
     the Bell Atlantic LIDB are included in Bell Atlantic Carrier Call
     Representative (CCR) Work Second or Automated call rate specified in
     Appendix A. Bell Atlantic will also launch queries as stated for
     validations to other companies' LIDBs.

                                      11

        This information is Bell Atlantic Proprietary and Confidential

<PAGE>
 
                                                                      APPENDIX C


                            EXCHANGE OF INFORMATION
                            -----------------------


Technical information will be furnished via the use of a Technical Questionnaire
to be provided by Bell Atlantic.  Such information will include, but not be 
limited to, the following:


1.   Central Office Exchange Names
2.   Usage Forecasts
3.   Local Central Office Characteristics
4.   Trunking Arrangements and Trunk Group Types
5.   Emergency Reporting System and Procedures
6.   Business Office Information
7.   Repair Service Information
8.   Name and Address Request Information
9.   Tariffs and Rate Information
10.  Customer Dialing Capabilities
11.  Access to EMI Records

                                      12

        This information is Bell Atlantic Proprietary and Confidential


<PAGE>
 
                                AMENDMENT NO. 2

                                    to the

                           INTERCONNECTION AGREEMENT

                                    between

                         BELL ATLANTIC-VIRGINIA, INC.

                                      and

                        MFS INTELENET OF VIRGINIA, INC.




     This Amendment No. 2 is made this 29th day of July, 1997, by and between 
Bell Atlantic-Virginia, Inc. ("BA"), a Virginia corporation with offices at 600 
East Main Street, Richmond, Virginia 23219, and MFS Intelenet of Virginia, Inc. 
("MFS"), a Delaware corporation with offices at 33 Whitehall Street, 15th Floor,
New York, New York 10004. (BA and MFS may be referred to individually as a 
"Party" and collectively as the "Parties").

                                  WITNESSETH:
                                  ----------

     WHEREAS, BA and MFS are Parties to an Interconnection Agreement under 
Sections 251 and 252 of the Telecommunications Act of 1996 dated effective as of
July 16, 1996 (the "Agreement"); and

     WHEREAS, the Parties now desire to amend the Agreement to reflect the 
agreement between the Parties to permit MFS, pursuant to Section 251(c)(4) of 
the Communications Act of 1934, to purchase retail telecommunications services 
from BA for resale by MFS in the State of Virginia;

     NOW, THEREFORE, in consideration of the promises and mutual agreements 
herein contained, the Parties agree to amend the Agreement as follows:

     1. Remove the existing cover page through page 64 of the Agreement and
     insert the attached revised cover page through page 63 of the Agreement,
     which includes deletion of the existing Section 12.0, Resale, in its
     entirety, and insertion of a revised Section 12.0, Resale, in its entirety.

     2. Insert a new Schedule 12.3, Support Services for Resale, as attached 
     hereto.
<PAGE>
 
     3.   Delete the existing Exhibit A and insert the revised Exhibit A, as 
     attached hereto.

     4.   Except for the foregoing, the substantive terms and provisions 
     contained in the Agreement shall remain in full force and effect.
     
     This Amendment may be executed in counterparts, each of which shall be 
deemed an original and all of which together shall constitute one and the same 
instrument.

                          [Intentionally Left Blank]

<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be 
duly executed as of the date first set forth above.





MFS INTELENET OF                             BELL ATLANTIC-
 VIRGINIA, INC.                               VIRGINIA, INC.


By: /s/ Kevin J. Dundon                      By: ___________________
    ----------------------------

Printed: Kevin J. Dundon                     Printed:_______________   
         -----------------------


Title:  Vice President -                     Title:_________________
       -------------------------                   
       Local Network Development
<PAGE>
 
     IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be 
duly executed as of the date first set forth above.





MFS INTELENET OF                         BELL ATLANTIC-
 VIRGINIA, INC.                           VIRGINIA, INC.



By:________________________              By:  /s/ H. R. Stallard
                                             --------------------------
Printed:___________________              Printed: H. R. Stallard
                                                 ----------------------
Title:_____________________              Title:   President and CEO  
                                               ------------------------

                                       3
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                           Dated as of July 16, 1996



                                by and between


                         BELL ATLANTIC-VIRGINIA, INC.

                                      and

                        MFS INTELENET OF VIRGINIA, INC.
<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------

<TABLE> 
<CAPTION> 
                                                                            Page
                                                                            ----
<S>                                                                         <C> 
1.0  DEFINITIONS                                                              2 

2.0  INTERPRETATION AND CONSTRUCTION                                         10

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION
     SCHEDULE                                                                11

4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)                           11
4.1  Scope                                                                   12 
4.2  Physical Architecture                                                   13
4.3  Initial Architecture                                                    13
4.4  Interconnection in Additional LATAs                                     14 
4.5  Interconnection Points for Different Types of Traffic                   15

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE 
     TRAFFIC PURSUANT TO SECTION 251(c)(2)                                   15
5.1  Scope of Traffic                                                        15
5.2  Trunk Group Connections and Ordering                                    15
5.3  Additional Switching System Hierarchy and Trunking Requirements         15
5.4  Signaling                                                               16
5.5  Grades of Service                                                       16
5.6  Measurement and Billing                                                 16
5.7  Reciprocal Compensation Arrangements--Section 251(b)(5)                 17

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC 
     PURSUANT TO 251(c)(2)                                                   18
6.1  Scope of Traffic                                                        18
6.2  Trunk Group Architecture and Traffic Routing                            18
6.3  Meet-Point Billing Arrangements                                         19
6.4  800/888 Traffic                                                         21

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC                     22
7.1  Information Services Traffic                                            22
7.2  LSV/VCI Traffic                                                         23
7.3  Transit Service                                                         24
7.4  911 E911 Arrangements                                                   25
7.5  Ancillary Traffic Generally                                             26

8.0  NUMBER RESOURCES, RATE CENTERS, AND RATING POINTS                       26
</TABLE> 
                                       i
<PAGE>
 
<TABLE> 
<S>                                                                         <C> 
9.0  NETWORK MAINTENANCE AND MANAGEMENT OUTAGES                             26

9.3  Interference or Impairment                                             28
9.4  Repeated or Willful Noncompliance                                      28
9.5  Outage Repair Standard                                                 28
9.6  Notice of Changes -- Section 251(c)(5)                                 28

10.0 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN AND
     INSTALLATION, MAINTENANCE, TESTING AND REPAIR                          28
10.1 Joint Network Reconfiguration and Grooming Plan                        28
10.2 Installation, Maintenance, Testing and Repair                          29 
10.3 Forecasting Requirements for Trunk Provisioning                        29 

11.0 UNBUNDLED ACCESS -- SECTION 251(c)(3)                                  30
11.1 Unbundled Local Loop(ULL) Transmission Types                           30 
11.2 Port Types                                                             31 
11.3 Trunk Side Local Transport                                             32
11.4 Limitations on unbundled Access                                        32  
11.5 Availability of Other Network Elements on an Unbundled Basis           33
11.6 Provisioning of Unbundled Local Loops                                  33
11.7 Maintenance of Unbundled Local Loops                                   35
11.8 Rates and Charges                                                      35  

12.0 RESALE -- SECTIONS 251(c)(4) and 251(b)(1)                             35
12.1 Availability of Retail Rates for Resale                                35
12.2 Availability of Wholesale Rates for Resale                             35
12.3 Availability of Support Services and Branding for Resale               35
12.4 Additional Terms Governing Resale and Use of BA Services               35

13.0 COLLOCATION -- SECTION 251(c)(6)                                       36

14.0 NUMBER PORTABILITY -- SECTION 251(b)(2)                                37
14.1 Scope                                                                  37
14.2 Procedures for Providing INP Through Remote Call Forwarding            38
14.3 Procedures for Providing INP Through Direct Call Inward Dial
     Trunks(Flex-DID)                                                       39
14.4 Procedures for Providing LTNP Through Full NXX Code Migration          39 
14.5 Receipt of Terminating Compensation on Traffic to INP'ed Numbers       39
14.6 Recovery of INP Costs Pursuant to FCC Order and Rulemaking             40  


15.0 DIALING PARITY -- SECTION 251(b)(3)                                    41 


16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                           41
</TABLE> 

                                      ii

<PAGE>
 
<TABLE> 
<S>                                                                      <C> 
17.0 DATABASES AND SIGNALING                                             41

18.0 COORDINATED SERVICE ARRANGEMENTS                                    42
18.1 Intercept and Referral Announcements                                42 
18.2 Coordinated Repair Calls                                            43
18.3 Customer Authorization                                              43

19.0 DIRECTORY SERVICES ARRANGEMENTS                                     43
19.1 Directory Listings and Directory Distributions                      44
19.2 Yellow Page Maintenance                                             45
19.3 Service Information Pages                                           45
19.4 Directory Assistance (DA): Call Completion                          46

20.0 COORDINATION WITH TARIFF TERMS                                      45

21.0 INSURANCE                                                           46

22.0 TERM AND TERMINATION                                                47

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                        48 

24.0 CANCELLATION CHARGES                                                48

25.0 INDEMNIFICATION                                                     48

26.0 LIMITATION OF LIABILITY                                             49 

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                      50
27.1 Certain Definitions                                                 50
27.2 Performance Standards                                               51  
27.3 Limitations                                                         51
27.4 Service Quality Standards                                           52
27.5 Records                                                             52 

28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL                           52

29.0 MISCELLANEOUS                                                       53
29.1 Authorization                                                       53
29.2 Independent Contractor                                              53
29.3 Force Majeure                                                       53
29.4 Confidentiality                                                     54
29.5 Choice of Law                                                       55
29.6 Taxes                                                               55
29.7 Assignment                                                          57
29.8 Billing and Payment; Disputed Amounts                               57
</TABLE> 

                                      iii

<PAGE>
 
<TABLE> 
<S>                                                                        <C> 
29.9   Dispute Resolution                                                  58
29.10  Notices                                                             59
29.11  Section 252(i) Obligations                                          59
29.12  Joint Work Product                                                  60
29.13  No Third Party Beneficiaries; Disclaimer of Agency                  61
29.14  No License                                                          61
29.15  Technology Upgrades                                                 61
29.16  Survival                                                            62 
29.17  Entire Agreement                                                    62
29.18  Counterparts                                                        62 
29.19  Modification, Amendment, Supplement or Waiver                       62
29.20  Successors and Assigns                                              62
29.21  Publicity                                                           62 
</TABLE> 

                        LIST OF SCHEDULES AND EXHIBITS
                        ------------------------------


Schedules
- ---------

Schedule 1.0    Certain Terms As Defined in the Act, As of July 16, 1996       
Schedule 3.0    Implementation Schedule     
Schedule 4.0    Interconnection Points in LATA
Schedule 4.2    Physical Architecture Diagram
Schedule 4.3    Initial Architecture Diagram  
Schedule 4.5    Interconnection Points for Different Types of Traffic
Schedule 6.3    Rate Elements Under Meet Point Billing
Schedule 12.3   Support Services for Resale
Schedule 27.0   Performance Interval Dates for Specified Activities
Schedule 27.1   MFS Service Quality Standards 


Exhibits
- --------

Exhibit A       Detailed Schedule of Itemized Charges
Exhibit B       Network Element Bona Fide Request
Exhibit C       Directory Assistance and Call Completion Services Agreement

                                      iv

<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement under Sections 251 and 252 of the 
Telecommunications Act of 1996, is effective as of the 16th day of July, 1996 
(the "Effective Date"), by and between Bell Atlantic-Virginia, Inc. ("BA"), a 
Virginia corporation with offices at 600 East Main Street, Richmond, Virginia 
23219, and MFS Intelenet of Virginia, Inc. ("MFS"), a Delaware corporation with 
offices at 33 Whitehall Street, 15th Floor, New York, New York 10004.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services. Switched 
Exchange Access Services, and other Telecommunication Services (all as defined 
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the 
respective obligations of the Parties and the terms and conditions under which 
the Parties will interconnect their networks and provide other services as 
required by the Act (as defined below) and additional services as set forth 
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996 
have specific requirements for interconnection, unbundling, and service resale, 
commonly referred to as the "Checklist", and the Parties intend that this 
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein 
and other good and valuable consideration, the receipt and sufficiency of which 
are hereby acknowledged, MFS and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA 
and MFS (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements, 
ancillary services, and wholesale Telecommunications Services available for 
resale within each LATA in which they both operate within Virginia. As such, 
this Agreement is an integrated package that reflects a balancing of interests 
critical to the Parties. It will be submitted to the Virginia State Corporation 
Commission and the Parties will specifically request that the Commission refrain
from taking any action to change, suspend or otherwise delay implementation of 
the Agreement. So long as the Agreement remains in effect, neither Party shall 
advocate before any legislative, regulatory, or other public forum that any 
term of this Agreement be modified or eliminated, unless otherwise mutually 
agreed by the Parties.

                                       1
<PAGE>
 
1.0  DEFINITIONS.

     As used in this Agreement, the following terms shall have the meanings 
specified below in this Section 1.0. For convenience of reference only, the
definitions of certain terms that are As Defined in the Act (as defined below)
are set forth on Schedule 1.0.

     1.1       "Act" means the Communications Act of 1934 (47 U.S.C. 151 et.
                                                                         --
seq.), as amended by the Telecommunications Act of 1996, and as from time to
- ---
time interpreted in the duly authorized rules and regulations of the FCC or the
Commission.

     1.2       "ADSL" or "Asymmetrical Digital Subscriber Line" means a
transmission technology which transmits an asymmetrical digital signal of up to
6 mbps to the Customer and to 640 kbps from the Customer.

     1.3       [Reserved]

     1.4       "Agreement" means this Interconnection Agreement under sections
251 and 252 of the Act and all Exhibits and Schedules appended hereto.

     1.5       "Ancillary Traffic," means all traffic that is destined for
ancillary services, or that may have special billing requirements, including but
not limited to the following: LSV/VCI, Directory Assistance, 911/E911, Operator
Services (call completion), 800/888 database query, LIDB, and information
services requiring special billing.

     1.6       "As Defined in the Act" means as specifically defined by the Act
and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.7       "As Described in the Act" means as described in or required by
the Act and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.8       "Automatic Number Identification" or "ANI" means a Feature Group
D signaling parameter which refers to the number transmitted through a network
identifying the billing number of the calling party.

     1.9       "Calling Party Number" or "CPN" is a Common Channel Signaling 
("CCS") parameter which refers to the number transmitted through a network 
identifying the calling party.

     1.10      "Central Office Switch" means a switch used to provide 
Telecommunications Services, including, but not limited to:

               (a)  "End Office Switch" or "End Office" which is used to 
terminate Customer station Loops for the purpose of interconnection to each 
other and to trunks; and

                                       2

<PAGE>
 
               (b)  "Tandem Switch" or "Tandem Office" which is a switching 
entity that is used to connect and switch truck circuits between and among End 
Office Switches and between and among End Office Switches and carriers' 
aggregation points, points of termination, or points of presence. An "Access 
Tandem Office" or "Access Tandem" is a Tandem Office with billing and recording 
capabilities that is used to provide Switched Exchange Access Services.

     A Central Office Switch may also be employed as a combination End 
Office/Tandem Office Switch.

     1.11      [Reserved]

     1.12      "CLASS Features" means certain CCS-based features available to 
Customers including, but not limited to; Automatic Call Back; Call Trace; Caller
Identification, and future offerings.

     1.13      "Collocation" means an arrangement whereby one Party's (the 
"Collocating Party") facilities are terminated in equipment necessary for 
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a 
second Party (the "Housing Party"). For purposes of Collocation, the "premises" 
of a Housing Party is limited to a Housing Party Wire Center, other mutually 
agreed-upon locations of the Housing Party, or any other location for which 
Collocation has been ordered by the FCC or Commission. Collocation may be 
"physical" or "virtual". In "Physical Collocation," the Collocating Party 
installs and maintains its own equipment in the Housing Party's premises. In 
"Virtual Collocation," the Housing Party owns, installs, and maintains equipment
dedicated to use by the Collocating Party in the Housing Party's premises. BA 
currently provides Collocation under terms, rates, and conditions as described 
in tariffs on file or soon to be filed with the FCC and the Commission. Upon 
request by either Party, BA and MFS will address the provision of additional 
types of Collocation arrangements, including additional physical locations and 
alternative utilizations of space and facilities.

     1.14      "Commission" means the Virginia State Corporation Commission.

     1.15      "Common Channel Signaling" or "CCS" means a method of 
transmitting call set-up and network control data over a digital signaling 
network separate from the public switched telephone network facilities that 
carry the actual voice or data traffic of the call. "SS7" means the common 
channel out of band signaling protocol developed by the Consultative Committee 
for International Telephone and Telegraph ("CCITT") and the American National 
Standards Institute ("ANSI"). BA and MFS currently utilized this out-of-band 
signaling protocol. "CCSAC" or "CCSAS" means the common channel signaling access
connection or service, respectively, which connects one Party's signaling point 
of interconnection ("SPOI") to the other Party's STP for the exchange of SS7 
messages.

                                       3
               
<PAGE>
 
     1.16 "Competing Local Exchange Carrier" or "CLEC" means any Local Exchange 
Carrier other than BA, operating as such in BA's certificated territory in 
Virginia. MFS is or will shortly become a CLEC.

     1.17 "Cross Connection" means a jumper cable or similar connection provided
pursuant to Collocation at the digital signal cross connect, Main Distribution 
Frame or other suitable frame or panel between (i) the Collocating Party's 
equipment and (ii) the equipment or facilities of the Housing Party.

     1.18 "Customer" means a third-party residence or business subscriber to 
Telecommunications Services provided by either of the Parties.

     1.19 "Dialing Parity" is As Defined in the Act.

     1.20 "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.21 "Digital Signal Level 0" or "DS0" means the 64 Kbps zero-level signal 
in the time-division multiplex hierarchy.

     1.22 "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level 
signal in the time-division multiplex hierarchy. In the time-division 
multiplexing hierarchy of the telephone network, DS1 is the initial level of 
multiplexing.

     1.23 "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level in
the time-division multiplex hierarchy. In the time-division multiplexing 
hierarchy of the telephone network, DS3 is defined as the third level of 
multiplexing.

     1.24 "Exchange Access" is As Defined in the Act.

     1.25 "Exchange Message Record" or "EMR" means the standard used for 
exchange of telecommunications message information among Local Exchange Carriers
for billable, non-billable, sample, settlement, and study data. EMR format is
contained in BR-010-200-010 CRIS Exchange Message Record, a Bell Communications
Research, Inc. ("Bellcore") document that defines industry standards for
Exchange Message Records.

     1.26 [Reserved]

     1.27 "FCC"means the Federal Communications Commission.

     1.28 "HDSL" or "High-Bit Rate Digital Subscriber Line" means a transmission
technology which transmits up to 784 Kbps simultaneously in both directions on a
two-wire channel using a 2 Binary / 1 Quartenary ("2B1Q") line code.

                                       4

<PAGE>
 
     1.29      "Independent Telephone Company" or "ITC" means any entity other 
than BA which, with respect to its operations within Virginia, is an "Incumbent 
Local Exchange Carrier" As Described in the Act.

     1.30      "Information Service Traffic" means Local Traffic or IntraLATA 
Toll Traffic which originates on a Telephone Exchange Service line and which is 
addressed to an information service provided over a Party's information services
platform.

     1.31      "Integrated Digital Loop Carrier" means a subscriber loop carrier
system which integrates within the switch at a DS1 level that is twenty-four
(24) loop transmission paths combined into a 1.544 Mbps digital signal.

     1.32      "Integrated Services Digital Network" or "ISDN" means a switched 
network service providing end-to-end digital connectivity for the simultaneous 
transmission of voice and data. Basic Rate Interface-ISDN ("BRI-ISDN'") provides
for digital transmission of two 64 kbps bearer channels and one 16 kbps data and
signaling channel (2B-D). Primary Rate Interface-ISDN ("PRI-ISDN") provides for 
digital transmission of twenty three (23) 64 kbps bearer channels and one 16 
kbps data and signaling channel (23 B+D).

     1.33      "Interconnection" is as Described in the Act, and means the 
connection of separate pieces of equipment or transmission facilities within, 
between, or among networks. The architecture of Interconnection may include, but
is not limited to, Collocation Arrangements, entrance facilities, and Mid-Span 
Meet arrangements.

     1.34      "Interexchange Carrier" or "IXC" means a carrier that provides, 
directly or indirectly, interLATA or intraLATA Telephone Toll Services.

     1.35      "Interim Number Portability" or "INP" means the use of existing 
and available call routing, forwarding, and addressing capabilities (e.g. remote
call forwarding) to enable a Customer to receive Telephone Exchange Service 
provided by any Local Exchange Carrier operating within the exchange area with 
which the Customer's telephone number(s) is associated, without having to change
the telephone number presently assigned to the Customer and regardless of 
whether the Customer's chosen Local Exchange Carrier is the carrier that 
originally assigned the number to the Customer.

     1.36      "InterLATA" is As Defined in the Act.

     1.37      "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.38      "Line Side" means an End Office Switch connection that provides 
transmission, switching and optional features suitable for Customer connection 
to the public switched network, including loop start supervision, ground start 
supervision, and signaling for basic rate ISDN service.

                                       5
<PAGE>
 
     1.39      "Line Status Verification" or "LSV" means an operator request for
a status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.40      "Local Access and Transport Area" or "LATA" is As Defined in the 
Act.
     
     1.41      "Local Exchange Carrier" or "LEC" is As Defined in the Act. The 
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.42      "Local Serving Wire Center" means a Wire Center that (i) serves 
the area in which the other Party's or a third party's Wire Center, aggregation 
point, point of termination, or point of presence is located, or any Wire Center
in the LATA in which the other Party's Wire Center, aggregation point, point of 
termination or point of presence is located in which the other Party has 
established a Collocation Arrangement or is purchasing an entrance facility, and
(ii) has the necessary multiplexing capabilities for providing transport
services.

     1.43      "Local Telephone Number Portability" or "LTNP" means "number 
portability" As Defined in the Act.

     1.44      "Local Traffic," means traffic that is originated by a Customer 
of one Party on that Party's network and terminates to a Customer of the other 
Party's network, within a given local calling area, or expanded area service 
("EAS") area, as defined in BA's effective Customer tariffs. Local Traffic does 
not include traffic originated or terminated by a commercial mobile radio 
service carrier.

     1.45      "Main Distribution Frame" or "MDF" means the primary point at 
which outside plant facilities terminate within a Wire Center, for 
interconnection to other telecommunications facilities within the Wire Center.

     1.46      "MECAB" means the Multiple Exchange Carrier Access Billing 
(MECAB) document prepared by the Billing Committee of the Ordering and Billing 
Forum ("OBF"), which functions under the auspices of the Carrier Liaison 
Committee ("CLC") of the Alliance for Telecommunications Industry Solutions 
("ATIS"). The MECAB document, published by Bellcore as Special Report 
SR-BDS-000983, contains the recommended guidelines for the billing of an 
Exchange Access service provided by two or more LECs, or by one LEC in two or 
more states, within a singe LATA.

     1.47      "MECOD" means the Multiple Exchange Carrier Ordering and Design 
(MECOD) Guidelines for Access Services - Industry Support Interface, a document 
developed by the Ordering/Provisioning Committee under the auspices of OBF. The
MECOD document, published by Bellcore as Special Report SR-STS-002643,
establishes methods for processing orders for Exchange Access service which is
to be provided by two or more LECs.

     1.48      "Meet-Point Billing" or "MPB" means an arrangement whereby two or
more LECs jointly provide to a third party the transport element of a Switched 
Exchange Access Service to one

                                       6
<PAGE>
 
of the LECs' End Office Switches, with each LEC receiving an appropriate share 
of the transport element revenues as defined by their effective Exchange Access 
tariffs. "Meet-Point Billing Traffic" means traffic that is subject to an 
effective Meet-Point Billing arrangement.

     1.49      "Mid-Span Meet" means an Interconnection architecture whereby two
carriers' fiber transmission facilities meet at a mutually agreed-upon 
Interconnection point.

     1.50      "Multiple Bill/Single Tariff" or "Multiple Bill/Multiple Tariff" 
means the MPB method whereby each LEC prepares and renders its own meet point 
bill in accordance with its own Tariff(s) for the portion of the 
jointly-provided Switched Exchange Access Service which the LEC provides.

     1.51      "Network Element" is As Defined in the Act.

     1.52      "Network Element Bona Fide Request" means the process described 
on Exhibit B that prescribes the terms and conditions relating to a Party's 
request that the other Party provide a Network Element not otherwise provided by
the terms of this Agreement.

     1.53      "North American Numbering Plan" or "NANP" means the numbering 
plan used in the United States that also serves Canada, Bermuda, Puerto Rico and
certain Caribbean Islands. The NANP format is a 10-digit number that consists of
a 3-digit NPA code (commonly referred to as the area code), followed by a 
3-digit NXX code and 4-digit line number.

     1.54      "Numbering Plan Area" or "NPA" is also sometimes referred to as 
an area code. There are two general categories of NPAs, "Geographic NPAs" and
"Non-Geographic NPAs." A Geographic NPA is associated with a defined geographic
area, and all telephone numbers bearing such NPA are associated with services
provided within that geographic area. A Non-Geographic NPA, also known as a
"Service Access Code" or "SAC Code," is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
area; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.55      "NXX," "NXX Code," or "End Office Code" means the three digit 
switch entity indicator (i.e. the first three digits of a seven digit telephone 
                         - -
number).

     1.56      "Permanent Number Portability" or "PNP" means the use of a 
database or other technical solution that comports with regulations issued by 
the FCC to provided LTNP for all customers and service providers.

     1.57      "Port Element" or "Port" means a line card (or equivalent) and 
associated peripheral equipment on and End Office Switch which serves as the 
Interconnection between individual loops or individual Customer trunks and the 
switching components of an End Office Switch and the associated switching 
functionality in that End Office Switch. Each Port is typically associated with 
one (or more) telephone number(s) which serves as the Customer's network 
address.

                                       7
<PAGE>
 
     1.58 "Rate Center Area" or "Exchange Area" means the specific geographic 
point and corresponding geographic area which has been identified by a given
LEC as being associated with a particular NPA-NXX code assigned to the LEC for
its provisions of Telephone Exchange Services. The Rate Center Area is the
exclusive geographic area which the LEC has identified as the area within which 
it will provide Telephone Exchange Services bearing the particular NPA-NXX 
designation associated with the specific Rate Center Area. A "Rate Center 
Point" is a specific geographic point, defined by a V&H coordinate, located
within the Rate Center Area and used to measure distance for the purpose of
billing Customers for distance-sensitive Telephone Exchange Services and Toll 
Traffic.

     1.59 "Rate Demarcation Point" means the point of minimum penetration at the
Customer's premises or other point, as defined in a Party's Tariffs, where 
network access recurring charges and LEC responsibility ends and beyond which 
Customer responsibility begins.

     1.60 "Rating Point" or "Routing Point" means a specific geographic point
identified by a specific V&H coordinate. The Rating Point is used to route in
bound traffic to specified NPA-NXXs and to calculate mileage measurements for
distance-sensitive transport charges of switched access services. Pursuant to
Bellcore Practice BR-795-100-100, the Rating Point may be an End Office
location, or a "LEC Consortium Point of Interconnection." Pursuant to that same
Bellcore Practice, examples of the latter shall be designated by a common
language location identifier (CLLI) code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point/Routing Point
must be located within the LATA in which the corresponding NPA-NXX is located.
However, the Rating Point Routing Point associated with each NPA-NXX need not be
the same as the corresponding Rate Center Point, nor must it be located within
the corresponding Rate Center Area, nor must there be a unique and separate
Rating Point Corresponding to each unique and separate Rate Center.

     1.61 "Reciprocal Compensation" is As Described in the Act, and refers to
the payment arrangements that recover costs incurred for the transport and 
termination of Local Traffic originating on one Party's network and terminating
on the other Party's network.

     1.62 "Service Control Point" or "SCP" means the node in the common channel
signaling network to which informational requests for service handling, such as 
routing, are directed and processed.  The SCP is a real time database system 
that, based on a query from a service switching point and via a Signaling
Transfer Point, performs subscriber or application-specific service logic,and
then sends instructions back to the SSP on how to continue call processing.

     1.63 "Signaling Transfer Point" or "STP" means a specialized switch that
provides SS7 network access and performs SS7 message routing and screening.

     1.64 "Switched Access Detail Usage Data" means a category 1101XX record as 
defined in the EMR Bellcore Practice BR-010-200-010.

     1.65 "Switched Access Summary Usage Data" means a category 1150XX record as
defined in the EMR Bellcore Practice BR-010-200-010.

                                      8
 
 

 


 





 


<PAGE>
 
     1.66 "Switched Exchange Access Service" means the offering of transmission
and switching services for the purpose of the origination or termination of Toll
Traffic.  Switched Exchange Access Service include but may not be limited to:
Feature Group A, Feature Group B, Feature Group D, 700 access, 800 access, 888 
access and 900 access.

     1.67 "Synchronous Optical Network" or SONET" means an optical interface 
standard that allows inter-networking of transmission products from multiple
vendors.  The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are direct
multiples of the base rate, up to 13.22 Gpbs.

     1.68 "Tariff" means any applicable federal or state Tariff of a Party, or
standard agreement or other document that sets forth the generally available 
terms and conditions under which a Party offers a particular service, facility, 
or arrangement.

     1.69 "Technically Feasible Point" is As Described in the Act.

     1.70 "Telecommunications" is As Defined in the Act.

     1.71 "Telecommunications Act" means the Telecommunications Act of 1996 and
any rules regulations promulgated thereunder.

     1.72 "Telecommunications Carrier" is As Defined in the Act.

     1.73 "Telecommunications Service" is As Defined in the Act.

     1.74 "Telephone Exchange Service," sometimes also referred to as "Exchange
Service," is As Defined in the Act.  Telephone Exchange Service generally 
provides the Customer with a telephonic connection to, and a unique telephone 
number address on, the public switched telecommunications network, and enables 
such Customer to place or receive calls to all other stations on the public 
switched telecommunications network.

     1.75 "Toll Traffic" means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that Party's network and is not Local Traffic or Ancillary Traffic.  Toll 
Traffic may be either "IntraLATA Toll Traffic" or "InterLATA Toll Traffic," 
depending on whether the originating and terminating points are within the same 
LATA.

     1.76 "Transit Traffic" means any traffic that originates from or terminates
at MFS's network, "transits" BA's network substantially unchanged, and
terminates to or originates from a third carrier's network, as the case may be.
"Transit Traffic Service" provides MFS with the ability to use its connection to
a BA Access Tandem Switch for the delivery of calls which originate or
terminate with MFS and terminate to or originate from a carrier other than
BA, such as another CLEC, a LEC other than BA, or a wireless carrier. In these
cases, neither the originating nor terminating Customer is a Customer of BA.
This service is provided through BA's Access Tandem

                                       9



<PAGE>
 
Switches. "Transit Traffic" and "Transit Traffic Service" do not include or 
apply to traffic that is subject to an effective Meet-Point Billing arrangement.

     1.77      "Trunk Side" means a Central Office Switch connection that is 
capable of, and has been programmed to treat the circuit as, connecting to 
another switching entity (e.g. another carrier's network). Truck Side 
                          - -
connections offer those transmission and signaling features appropriate for the 
connection of switching entities.

     1.78      "Unbundled Local Loop Element" or "ULL" means a transmission path
that extends from a Main Distribution Frame, DSX-panel, or functionally
comparable piece of equipment in the Customer's serving End office to the Rate
Demarcation Point (or network interface device (NID) if installed) in or at a
Customer's premises. The actual loop transmission facilities used to provide an
ULL may utilize any of several technologies.

     1.79      "Verification with Call Interruption" or "VCI" means a service 
that may be requested and provided when Line Status Verification has determined 
that a line is busy due to an ongoing call. VCI is an operator interruption of 
that ongoing call to inform the called party that a calling party is seeking to 
complete his or her call to the called party.

     1.80      "Voice Grade" means either an analog signal of 300 to 3000 Hz or 
a digital signal of 56/64 kilobits per second. When referring to digital voice 
grade service (a 56/64 kbps channel), the terms "DS-O" or "sub-DS-1" may also be
used.

     1.81      "Wire Center" means a building or portion thereof in which a 
Party has the exclusive right of occupancy and which serves as a Routing Point 
for Switched Exchange Access Service.

2.0  INTERPRETATION AND CONSTRUCTION.

     2.1       All references to Sections, Exhibits and Schedules shall be 
deemed to be references to Sections of, and  Exhibits and Schedules to, this 
Agreement unless the context shall otherwise require. The headings used in this 
Agreement are inserted for convenience of reference only and are not intended to
be a part of or to affect the meaning of this Agreement. Unless the context 
shall otherwise require, any reference to any agreement, other instrument 
(including BA or other third party offerings, guides or practices), statue, 
regulation, rule or tariff is to such agreement, instrument, statute, 
regulation, or rule or tariff as amended and supplemented from time to time 
(and, in the case of a statute, regulation, rule or tariff, to any successor 
provision).

     2.2       Subject to the terms set forth in Section 20, each Party hereby 
incorporates by reference those provisions of its tariffs that govern the 
provision of any of the services or facilities provided hereunder. If any 
provision of this Agreement and an applicable tariff cannot be reasonably 
construed or interpreted to avoid conflict, the Parties agree to negotiate in 
good faith to reconcile and resolve such conflict. If any provision contained in
this main body of the Agreement and any Exhibit hereto cannot be reasonably
construed or interpreted to avoid conflict, the

                                      10

<PAGE>
 
provision contained in this main body of the Agreement shall prevail. The fact 
that a condition, right, obligation, or other term appears in this Agreement but
not in any such tariff shall not be interpreted as, or be deemed grounds for 
finding, a conflict for purposes of this Section 2.

3.0  INTERCONNECTION ACTIVATION DATES AND IMPLEMENTATION SCHEDULE.

     3.1       Subject to the terms and conditions of this Agreement, each Party
shall exercise its best efforts to adhere to the Interconnection Activation
Dates and Network Implementation Schedule set forth in Schedule 3.0, and to
provide fully operational service predominantly over its own Telephone Exchange
Service facilities to business and residential Customers upon the achievement of
the milestones in said Schedule for each listed LATA in Virginia. For purposes
of this Agreement, MFS's service in Virginia shall be considered provided
"predominantly over its own Telephone Exchange Service facilities" if MFS uses
its own Central Office Switch(es) (as opposed to resale of another carrier's
Telephone Exchange Service or Ports) to serve the majority of its Telephone
Exchange Service Customers, its own interoffice transport facilities for the
majority of its interoffice transport needs, and its own local loops (or
functional equivalent), in addition to resale of other carriers' Telephone
Exchange Service or ULLs, to serve its Telephone Exchange Service Customers.

     3.2       Schedule 3.0 may be revised and supplemented from time to time 
upon the mutual agreement of the Parties to reflect the intention of the Parties
to interconnect in additional LATAs pursuant to subsection 4.4 by attaching one 
or more supplementary schedules to Schedule 3.0. The Parties stipulate and agree
that the performance of the terms of this Agreement will satisfy BA's obligation
to provide Interconnection under Section 251 of the Act, and the requirements 
of the Competitive Checklist, under Section 271 of the Act. MFS represents that 
it is, or intends to become, a provider of Telephone Exchange Service to 
residential and business subscribers offered exclusively over its own Telephone 
Exchange Service facilities or predominantly over its own Telephone Exchange 
Service facilities in combination with the resale of the Telecommunications 
Services of other carriers.

4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)

     The types of Traffic to be exchanged under this Agreement shall be Local 
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Transit 
Traffic, Meeting Point Billing Traffic, and Ancillary Traffic. Subject to the 
terms and conditions of this Agreement, Interconnection of the Parties 
facilities and equipment for the transmission and routing of Local Traffic and 
Toll Traffic pursuant to this Section 4 shall be established on or before the 
corresponding "Interconnection Activation Date" shown for each such LATA within 
Virginia on Schedule 3.0. Both Schedule 3.0 and Schedule 4.0 may be revised and 
supplemented from time to time upon the mutual agreement of the Parties to 
reflect Interconnection in additional LATAs in Virginia pursuant to subsection 
4.4 by attaching one or more supplementary addenda to such Schedules.

                                      11
<PAGE>
 
     4.1  SCOPE

          4.1.1   Section 4 describes the architecture for Interconnection of 
the Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct truck groups:

          Traffic Exchange Trunks for the transmission and routing of
          ----------------------- 
          terminating Local Traffic and IntraLATA Toll Traffic between their
          respective Telephone Exchange Service customers pursuant to Section
          251 (c)(2) of the Act, in accordance with Section 5 below;

          Access Toll Connecting Trunks for the transmission and routing of
          -----------------------------
          Exchange Access traffic between MFS Telephone Exchange Service
          customers and purchasers of BA's Switched Exchange Access Service via
          a BA Access Tandem, pursuant to Section 251 (c)(2) of the Act, in
          accordance with Section 6 below;

          Information Services Trunks for the transmission and routing of
          ---------------------------
          terminating Information Services Traffic in accordance with Section 7
          below;

          LSV/VCI Trunks for the transmission and routing of termination LSV/VCI
          --------------
          traffic, in accordance with Section 7 below;

          911/E911 Trunks for the transmission and routing of terminating
          ---------------
          E911/911 traffic, in accordance with Section 7 below;

          Directory Assistance Trunks for the transmission and routing of
          ---------------------------
          terminating directory assistance traffic, in accordance with
          subsection 19.4 below; and

          Operator service (call completion) Trunks for the transmission and
          -----------------------------------------
          routing of terminating call completion traffic, in accordance with
          subsection 19.4 below.

          4.1.2   The SONET interconnection arrangement described in subsection
4.2 shall be (i) used only for the termination of Local Traffic and IntraLATA
Toll Traffic until such time as the Parties have agreed to appropriate
compensation arrangements relating to the exchange of other types of traffic
over such system, and (ii) subject to the Parties' reaching agreement on an
appropriate compensation arrangement in the event either Party will be providing
or utilizing (in terms of minutes of use) significantly more than one-half of
the SONET facility. Unless otherwise agreed to by the Parties, the SONET system
described herein shall not be used to exchange InterLATA Toll Traffic. Until the
SONET system has been established by the Parties in accordance with subsection
4.3 and this subsection 4.1.2, the Parties agree to adopt an initial
interconnection architection for the exchange of Local Traffic and Toll
(IntraLATA and InterLATA) Traffic.

                                      12
     
<PAGE>
 
          4.1.3     To the extent required by Section 251 of the Act, the 
Parties represent that the arrangements provided in subsections 4.2 and 4.3 of 
this Agreement provide for Interconnection to each other's networks at any 
technically feasible point. For the purposes of this Agreement, the Parties 
agree that Interconnection for the transport and termination of traffic may take
place, in the case of BA, at a terminating End Office, an Access Tandem, a Local
Serving Wire Center and/or other points as specified herein, and, in the case of
MFS, at a node or Central Office and/or other points as specified herein 
(collectively, the "Interconnection Points" or "IPs").

          4.1.4     The Parties shall establish physical interconnection points 
at the available IPs at the locations designated in Schedule 4.0. The mutually 
agreed-upon IPs on the MFS network at which MFS will provide transport and 
termination of traffic shall be designated as the MFS Interconnection Points 
("M-IPs"); the mutually agreed-upon IPs on the BA network shall be designated as
the BA Interconnection Points ("BA-IPs"), provided that, for the purpose of
charging for the transport of traffic from the BA-IP to the M-IP in any given
LATA, the M-IP shall be no further than an entrance facility away from the BA-IP
in such LATA. The Parties may by mutual agreement establish additional
interconnection points at any technically feasible points consistent with the
Act.

     4.2  PHYSICAL ARCHITECTURE. In each LATA identified on Schedule 4.0, MFS
and Bell Atlantic shall jointly engineer and operate a diverse Synchronous 
Optical Network ("SONET") transmission system by which they shall interconnect 
their networks pursuant to the joint network reconfiguration and grooming plan 
specified in subsection 10.1 ("Joint Grooming Plan"), and according to the 
following specifications:

          4.2.1     The SONET system shall be used to deliver appropriate 
traffic to a mutually agreed-upon Interconnection Point on each Party's network.

          4.2.2     The SONET transmission system in each LATA shall be 
configured substantially as illustrated in Schedule 4.2 and pursuant to the 
Joint Grooming Plan, or as otherwise mutually agreed. The Parties shall agree
upon which Party or Parties shall be responsible for procuring, installing, and
maintaining the agreed-upon Optical Line Terminating Multiplexor ("OLTM")
equipment, fiber optic facilities and other equipment pursuant to the Joint
Grooming Plan, as illustrated in that Schedule.

          4.2.3     The physical interface of MFS's and BA's facilities 
necessary to effect SONET transmission shall be at the optical level via a 
Mid-Span Meet or other comparable means, or as otherwise mutually agreed.

     4.3  INITIAL ARCHITECTURE

          4.3.1     The Parties agree to provide initial interconnection 
arrangements utilizing electrical handoff, substantially as illustrated in 
Schedule 4.3, for a period of no more than eighteen (18) months after the later 
of the Effective Date and the LATA Start Date set forth for the LATA in Schedule
3.0; provided, however, that such initial interconnection arrangements

                                      13
<PAGE>
 
shall continue until (i) facilities suitable for the SONET arrangements 
described in subsection 4.2 are established by each of the Parties in its own 
sole discretion in the LATA at the mutually agreed-upon SONET meet points and 
made available, and (ii) the Parties have agreed upon fully compatible OLTM 
equipment for use with such facilities.

          4.3.2  The Parties agree to utilize the M-IP and BA-IP in each LATA as
designated in Schedule 4.0 as the points from which each Party will provide the
transport and termination of traffic.

          4.3.3  MFS shall provide its own facilities for the delivery of
traffic to a collocation arrangement established at the BA-IP pursuant to
Section 13. Bell Atlantic shall provide transport and termination of the traffic
beyond the BA-IP.

          4.3.4  BA shall purchase an MFS entrance facility (and any necessary 
multiplexing) from the BA-IP to the M-IP for the delivery of traffic to the 
M-IP. Alternatively, BA may choose to provide its own facilities to a 
collocation arrangement established at the M-IP pursuant to Section 13. MFS 
shall provide transport and termination of the traffic beyond the M-IP.

          4.3.5  Under this initial architecture described in this subsection
4.3, either Party may utilize the Traffic Exchange Trunks for the termination of
its InterLATA Toll Traffic in accordance with the terms contained in Section 5
below and pursuant to the other Party's Switched Exchange Access Service
tariffs. The other Party's Switched Exchange Access Service rates shall apply to
such Traffic. Such InterLATA Toll Traffic may not be routed over the trunk
groups under the SONET architecture described in subsection 4.2, however, unless
specifically agreed to by the Parties.

     4.4  INTERCONNECTION IN ADDITIONAL LATAs

          4.4.1  If MFS determines to offer Telephone Exchange Services in any
LATA not listed in Schedule 3.0 in which BA also offers Telephone Exchange
Services, MFS shall provide written notice to BA of the need establish
Interconnection in such LATA pursuant to this Agreement.

          4.4.2  The notice provided in subsection 4.4.1 shall include (i) the
initial Routing Point MFS has designated in the new LATA; (ii) MFS's requested
Interconnection Activation Date (and related milestone dates in accordance with
the format in Schedule 3.0); and (iii) a non-binding forecast of MFS's trunking
requirements.

          4.4.3  Unless otherwise agreed to by the Parties, the Parties shall
designate the Wire Center MFS has identified as its initial Routing Point in the
LATA as the M-IP in that LATA and shall designate a mutually agreed BA Local
Serving Wire Center that houses an Access Tandem Office within the LATA nearest
to the M-IP (as measured in airline miles utilizing the V&H coordinates method)
as the BA-IP in that LATA, provided that, for the

                                      14

<PAGE>
 
purpose of charging for the transport of traffic from the BA-IP to the M-IP, 
the M-IP shall be no further than an entrance facility away from the BA-IP.

          4.4.4  The Parties shall agree upon an addendum to Schedule 3.0 to
reflect the schedule applicable to each new LATA requested by MFS; provided,
however, that unless agreed by the Parties, the Interconnection Activation Date
in a new LATA shall not be earlier than forty-five (45) days after receipt by BA
of all complete and accurate trunk orders and routing information. Within ten
(10) business days of BA's receipt of MFS's notice, BA and MFS shall confirm the
BA-IP, the M-IP and the Interconnection Activation Date for the new LATA by
attaching an addendum to Schedule 3.0.

     4.5  INTERCONNECTION POINTS FOR DIFFERENT TYPES OF TRAFFIC. Each Party
shall make available Interconnection Points and facilities for routing of
traffic from those Interconnection Points as designated in Schedule 4.5. Any
additional traffic that is not covered in Schedule 4.5 shall be subject to
separate negotiations between the Parties, except that (i) either Party may
deliver traffic of any type or character to the other Party for termination as
long as the delivering Party pays the receiving Party's then current Switched
Exchange Access rates for such traffic, and (ii) upon a bona fide request from
                                                        ---- ----
either Party, the Parties will exercise all reasonable efforts to conclude an
agreement covering the exchange of such traffic.

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO 
SECTION 251(C)(2)

     5.1  SCOPE OF TRAFFIC. Section 5 prescribes parameters for trunk groups
(the "Traffic Exchange Trunks") to be effected over the Interconnections
specified in Section 4.0 for the transmission and routing of Local Traffic and
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1  Trunk group connections will be made at a DS-1 level or higher
for exchange of Local and Toll Traffic. Higher speed connections shall be made,
when and where available, in accordance with the Joint Grooming Plan prescribed
in Section 10. Ancillary Traffic trunk groups may be made below a DS-1 level, as
may be agreed to by the Parties.

          5.2.2  Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

          5.3.1  For purposes of routing MFS traffic to BA, the subtending
arrangements between BA Access Tandem Switches and BA End Office Switches shall
be the same as the Access Tandem/End Office subtending arrangements BA maintains
for the routing of its own' or other carriers' traffic. For purposes of routing
BA traffic to MFS, the subtending arrangements.

                                      15

<PAGE>
 
between MFS Access Tandem Switches (or functional equivalent) and MFS End Office
Switches (or functional equivalent) shall be the same as the Access Tandem/End
Office subtending arrangements (or functional equivalent) which MFS maintains
for the routing of its own or other carriers' traffic.

     5.4  SIGNALING

     Each Party will provide the other Party with access to its databases and
associated signaling necessary for the routing and completion of the other
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5  GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Grooming Plan as set forth in Section
10.

     5.6  MEASUREMENT AND BILLING

       5.6.1  For billing purposes, each Party shall pass Calling Party Number
("CPN") information on each call carried over the Traffic Exchange Trunks,
wherever technically feasible. At such time as either Party has the ability, as
the Party receiving the traffic, to use such CPN information to classify on an
automated basis traffic delivered by the other Party as either Local Traffic or
Toll Traffic, such receiving Party shall bill the originating Party the Local
Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of Traffic for which CPN is
passed, as provided in Exhibit A and applicable Tariffs.

       5.6.2  If, under the circumstances set forth in subsection 5.6.1, it is
not technically feasible for the originating Party to pass CPN on up to ten
percent (10%) of calls, the receiving Party shall bill the originating Party the
Local Traffic termination rates, Intrastate Exchange Access rates, or Interstate
Exchange Access rates applicable to each minute of traffic, as provided in
Exhibit A and applicable Tariffs, for which CPN is passed. For the remaining up
to ten percent (10%) of calls without CPN information, the receiving Party shall
bill the originating Party for such traffic as Local Traffic termination rates.
Intrastate Exchange Access rates, or Interstate Exchange Access rates applicable
to each minute of traffic, as provided in Exhibit A and applicable Tariffs, in
direct proportion to the minutes of use of calls passed with CPN information.

       5.6.3  If it is not technically feasible for the originating Party to
pass CPN on more than ten percent (10%) of calls, or if the receiving Party
lacks the ability to use CPN information to classify on an automated basis
traffic delivered by the other Party as either Local Traffic or Toll Traffic,
and the originating Party chooses to combine Local and Toll Traffic on the same
trunk group, it will supply an auditable Percent Local Use ("PLU") report
quarterly, based on the previous three months' traffic, and applicable to the
following three months. If the originating Party also chooses to combine
Interstate and Intrastate Toll Traffic on the same trunk

                                      16

<PAGE>
 
group, it will supply an auditable Percent Interstate Use ("PIU") report 
quarterly, based on the previous three months' terminating traffic, and 
applicable to the following three months. In lieu of the foregoing PLU and/or 
PIU reports, the Parties may agree to provide and accept reasonable surrogate 
measures for an agreed-upon interim period.

          5.6.4  Measurement of billing minutes for purposes of determining 
terminating compensation shall be in conversation seconds.

     5.7  RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

     Reciprocal Compensation arrangements address the transport and termination 
of Local Traffic.  BA's delivery of Traffic to MFS that originated with a third 
carrier is addressed in subsection 7.3.  Where MFS delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, MFS shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by MFS. Compensation for the transport and termination of traffic not
specifically addressed in this subsection 5.7 shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

          5.7.1  Nothing in this Agreement shall be construed to limit either 
Party's ability to designate the areas within which that Party's Customers may 
make calls which that Party rates as "local" in its Customer Tariffs.

          5.7.2  The Parties shall compensate each other for transport and 
termination of Local Traffic in an equal and symmetrical manner at the rates 
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto) or, if 
not set forth therein, in the applicable Tariff(s) of the terminating Party, as 
the case may be. These rates are to be applied at the M-IP for traffic delivered
by BA, and at the BA-IP for traffic delivered by MFS. No additional charges,
including port or transport charges, shall apply for the termination of Local
Traffic delivered to the BA-IP or the M-IP, except as set forth in Exhibit A.  
When Local Traffic is terminated over the same trunks as Toll Traffic, any port
or transport or other applicable access charges related to the Toll Traffic
shall be prorated to be applied only to the Toll Traffic.

          5.7.3  The Reciprocal Compensation arrangements set forth in this 
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs.

          5.7.4  Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5.

          5.7.5  The designation of Traffic as Local or Toll for purposes of 
compensation shall be based on the actual originating and terminating points of 
the complete end-to-end call, regardless of the carrier(s) involved in carrying 
any segment of the call.

                                      17
 
<PAGE>
 
          5.7.6  Each Party reserves the right to measure and audit all Traffic 
to ensure that proper rates are being applied appropriately. Each Party agrees 
to provide the necessary Traffic data or permit the other Party's recording 
equipment to be installed for sampling purposes in conjunction with any such 
audit.

          5.7.7  The Parties will engage in settlements of alternate-billed 
calls (e.g. collect, calling card, and third-party billed calls) originated or 
       - -
authorized by their respective Customers in Virginia in accordance with the 
terms of an appropriate billing services agreement for intraLATA intrastate 
alternate-billed calls or such other arrangement as may be agreed to by the 
Parties.

6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(C)(2).

     6.1  SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over 
the Interconnections specified in Section 4 for the transmission and routing of 
traffic between MFS Telephone Exchange Service Customers and Interexchange 
Carriers ("Access Toll Connecting Trunks"). This includes casually-dialed (10XXX
and 101XXXX) traffic.

     6.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

        6.2.1  MFS shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from MFS's Customers.

        6.2.2  Access Toll Connecting Trunks shall be used solely for the 
transmission and routing of Exchange Access to allow MFS's Customers to connect 
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to an BA Access Tandem.

        6.2.3  The Access Toll Connecting Trunks shall be two-way trunks 
connecting an End Office Switch MFS utilizes to provide Telephone Exchange 
Service and Switched Exchange Access in a given LATA to an Access Tandem BA 
utilizes to provide Exchange Access in such LATA.

        6.2.4  The Parties shall jointly determine which BA Access Tandem(s) 
will be subtended by each MFS End Office Switch.  MFS's End Office switch shall
subtend the BA Access Tandem that would have served the same rate center on BA's
network.  Alternative configurations will be discussed as part of the Joint 
Plan.

     6.3  MEET-POINT BILLING ARRANGEMENTS

                                      18

<PAGE>
 
          6.3.1  MFS and BA will establish Meet-Point Billing arrangements in 
order to provide a common transport option to Switched Access Services Customers
via an Access Tandem Switch in accordance with the Meet-Point Billing guidelines
contained in the OBF's MECAB and MECOD documents, except as modified herein, and
BA's Virginia Tariff Number 217, Section 2.4.8.  The arrangements described in 
this Section 6 are intended to be used to provide Switched Exchange Access 
Service that originates and/or terminates on a Telephone Exchange Service that 
is provided by either Party, where the transport component of the Switched 
Exchange Access Service is routed through a Tandem Switch that is provided by 
BA.

          6.3.2  In each LATA, the Parties shall establish MPB arrangements 
between the applicable Rating Point/BA Local Serving Wire Center combinations.

          6.3.3  Interconnection for the MPB arrangement shall occur at the 
BA-IP in the LATA, unless otherwise agreed to by the Parties.

          6.3.4  MFS and BA will use reasonable efforts, individually and 
collectively, to maintain provisions in their respective state access tariffs, 
and or provisions within the National Exchange Carrier Association ("NECA") 
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

          6.3.5  Each Party shall implement the "Multiple Bill/Single Tariff" or
"Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an IXC 
for the portion of the jointly provided telecommunications service provided by 
that Party.

          6.3.6  The rate elements to be billed by each Party are as set forth 
in Schedule 6.3.  The actual rate values for each Party's affected access 
service rate element shall be the rates contained in that Party's own effective 
federal and state access tariffs, or other document that contains the terms 
under which that Party's access services are offered.  The MPB billing 
percentages for each Rating Point/BA Local Serving Wire Center combination shall
be calculated in accordance with the formula set forth in subsection 6.3.16 
below.

          6.3.7  Each Party shall provide the other Party with the billing name,
billing address, and Carrier Identification Code ("CIC") of the IXC, and 
Identification of the IXC's Local Serving Wire Center in order to comply with 
the MPB notification process as outlined in the MECAB document via facsimile or 
such other media as the Parties may agree to.

          6.3.8  BA shall provide MFS with the Switched Access Detail Usage Data
(category 1101XX records) on magnetic tape or via such other media as the 
Parties may agree to, no later than ten (10) business days after the date the 
usage occurred.

          6.3.9  MFS shall provide BA with the Switched Access Summary Usage 
Data (category 1150XX records) on magnetic tape or via such other media as the 
Parties may agree, no later than ten (10) business days after the date of its 
rendering of the bill to the relevant IXC, which bill shall be rendered no less 
frequently than monthly.

                                      19

<PAGE>
 
          6.3.10  Each Party shall coordinate and exchange the billing account 
reference ("BAR") and billing account cross reference ("BACR") numbers or 
Operating Company Name ("OCN"), as appropriate, for the MPB Service. Each Party 
shall notify the other if the level of billing or other BAR/BACR elements 
change, resulting in a new BAR/BACR number, or if the OCN changes.

          6.3.11. Errors may be discovered by MFS, the IXC or BA. Each Party 
agrees to provide the other Party with notification of any errors it discovers 
within two (2) business days of the date of such discovery. In the event of a 
loss of data, both Parties shall cooperate to reconstruct the lost data and, if 
such reconstruction is not possible, shall accept a reasonable estimate of the 
lost data based upon prior usage data.

          6.3.12  Either Party may request a review or audit of the various
components of access recording up to a maximum of two (2) audits per calender
year. All costs associated with each review and audit shall be borne by the
requesting Party. Such review or audit shall be conducted subject to
confidentiality protection and during regular business hours. A Party may
conduct additional audits, at its expense, upon the other Party's consent, which
consent shall not be unreasonably withheld.

          6.3.13. Nothing contained in this subsection 6.3, shall create any 
liability for damages, losses, claims, costs, injuries, expenses or other 
liabilities whatsoever on the part of either Party (other than as may be set 
forth in MECAB or in any applicable Tariff).

          6.3.14. The Parties shall not charge one another for the services 
rendered or information provided pursuant to this subsection 6.3.

          6.3.15  MPB will apply for all traffic bearing the 500, 900, 800/888 
(to the extent provided by an IXC) or any other non-geographic NPA which may be 
likewise designated for such traffic in the future.

          6.3.16  In the event MFS determines to offer Telephone Exchange 
Services in another LATA in which BA operates an Access Tandem Switch, BA shall 
permit and enable MFS to subtend the BA Access Tandem Switch(es) designated for 
the BA End Offices in the area where the MFS Rating Point(s) associated with 
the NPA-NXX(s) to from which the Switched Exchange Access Services are homed. 
The MPB billing percentages for each new Rating Point/BA Local Serving Wire 
Center combination shall be calculated according to the following formula:

                      a/(a + b) = MFS Billing Percentage
                                      and
                      b/(a + b) = BA Billing Percentage

                  where:
                  -----

                  a = the airline mileage between the Rating Point and the 
             actual point of interconnection for the MPB arrangement: and

                                      20
<PAGE>
 
               b = the airline mileage between the BA Local Serving Wire Center 
          and the actual point of interconnection for the MPB arrangement.

MFS shall inform BA of the LATA in which it intends to offer Telephone Exchange 
Services and its calculation of the billing percentages which should apply for 
such arrangement, as part of the notice required by subsection 4.4.1 above. 
Within ten (10) business days of MFS's delivery of notice to BA, BA and MFS 
shall confirm the new Rating Point/BA Local Serving Wire Center combination and 
billing percentages. Nothing in this subsection 6.3.16 shall be construed to 
limit MFS"S ability to select to interconnect with BA in additional LATAs by
means of Interconnection at a Local Serving Wire Center, to the extent that such
Interconnection is permitted under this Agreement.

     6.4  800/888 TRAFFIC

     The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

          6.4.1.  When MFS delivers untranslated 800/888 calls to BA for
completion

                  (a)  to an IXC, BA shall: 

                       (i)   Provide a MPB record in an industry standard format
                       to MFS; and
 
                       (ii)  Bill the IXC the appropriate BA query charge
                       associated with the call.

                  (b)  as an IntraLATA call to BA or another LEC in the LATA, BA
shall  

                       (i)   Provide a copy record in an industry standard
                       format to MFS:

                       (ii)  Bill MFS the appropriate BA query charge associated
                       with the call; and        

                       (iii) Submit the call records to ITORP for payment by BA
                       or the LEC that is the 800/888 service provider of MFS's
                       and any intermediate LEC's Tariffed Exchange Access 
                       charges and query charges.

          6.4.2   When BA delivers 800/888 calls originated by BA's or another
LEC's Customers to MFS for completion

                                      21
<PAGE>
 
                    (a)  to MFS in its capacity as an IXC. BA shall:
                         
                         (i)     Bill MFS the appropriate BA query charge
                         associated with the call; and

                         (ii)    Bill MFS the appropriate FGD Exchange Access 
                         charges associated with the call.

                    (b)  as an IntraLATA call to MFS in its capacity as a LEC.
 
                         (i)     BA shall submit the appropriate call records to
                         ITORP for payment by MFS of BA's (and another LEC's, if
                         appropriate) Tariffed Exchange Access charges; and

                         (ii)    MFS shall pay the originating LEC's appropriate
                         query charge associated with the call.


7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to MFS-originated Information
Services Traffic directed to an information services platform connected to BA's
network. At such time as MFS connects Information Services platforms to its
network, the Parties shall agree upon a suitable arrangement for BA-originated
Information Services Traffic.

          7.1.1     MFS shall route Information Services Traffic that 
originates on its own network to the appropriate information services 
platform(s) connected to BA's network. MFS will establish a dedicated trunk 
group to the BA information services serving switch. This trunk group will be 
utilized to allow MFS to route information service traffic originated on its 
network to BA.

          7.1.2     MFS shall provide an electronic file transfer or monthly 
magnetic tape containing recorded call detail information to BA.

          7.1.3     BA shall provide to MFS via electronic file transfer or
magnetic tape or other means as available all necessary information to rate the 
Information Services Traffic to MFS's Customers pursuant to the BA's agreements 
with each information services provider. Information shall be provided in as 
timely a fashion as practical in order to facilitate record review and reflect 
actual prices set by the individual information services providers.

          7.1.4     MFS shall bill and collect such information services 
provider charges and remit the amounts collected to BA less:

                                      22
<PAGE>
 
          (a)       The Information Services Billing and Collection fee set 
     forth in Exhibit A; and

          (b)       An uncollectibles reserve calculated based on the 
     uncollectibles reserve in BA's billing and collection agreement with the 
     applicable information services provider; and

          (c)       Customer adjustments provided by MFS.

MFS shall provide to BA sufficient information regarding uncollectibles and 
Customer adjustments to allow BA to pass through the adjustments to the 
information services provider, and BA shall pass through such adjustments. 
However, if the information services provider disputes such adjustments and 
refuses to accept such adjustments, MFS shall reimburse BA for all such disputed
adjustments. Final resolution regarding all disputed adjustments shall be solely
between MFS and the information services provider.

          7.1.5     Nothing in this Agreement shall restrict either Party from 
offering to its Telephone Exchange Service Customers the ability to block the 
completion of Information Service Traffic.

          7.1.6     The Parties may agree to separate arrangements for the 
billing and compensation of variable rated (e.g. 970, 540) information services.
                                            -

          7.1.7     The Information Services Traffic addressed herein does not 
include 555 traffic or similar traffic with AIN service interfaces.

     7.2  LSV/VCI TRAFFIC

          7.2.1     Each Party shall offer LSV and VCI services to enable its 
Customers to verify and/or interrupt calls of the other Party's Customers. In 
such instances, the other Party shall accept and respond to LSV and VCI requests
from the operator bureau of the requesting Party. Both the requesting Party 
(Party A) and the responding Party (Party B) shall perform in accordance with 
the terms set forth in this subsection 7.2 and pursuant to inter-Party rates to 
be agreed upon between the Parties.

          7.2.2     The Party B operator shall only verify the status of the 
line (LSV) or interrupt the line to inform the called party that there is a call
waiting. The Party B operator will not complete the telephone call of the
Customer initiating the LSV VCI request. The Party B operator will only make one
LSV/VCI attempt per Customer operator bureau telephone call, and the applicable
charges apply whether or not the called party releases the line.

          7.2.3.    Each Party's operator bureau shall accept LSV and VCI 
inquiries from the operator bureau of the other Party in order to allow 
transparent provision of LSV/VCI Traffic between the Parties' networks.

                                      23
<PAGE>
 
          7.2.4  Each Party shall route LSV/VCI Traffic inquires over separate 
direct trunks (and not the Local/IntraLATA/InterLATA Trunks) established 
between the Parties' respective operator bureaus. Each Party shall offer 
interconnection for LSV/VCI traffic at its Local Serving Wire Center, operator 
services Tandem Office subtended by such Local Serving Wire Center, or other 
mutually agreed point in the LATA. Separate LSV/VCI trunks delivered at the 
Local Serving Wire Center will be directed to the operator services Tandem 
Office designated by Party B. Unless otherwise mutually agreed, the Parties 
shall configure LSV/VCI trunks over the Interconnection architectures in 
accordance with the terms of Section 4, consistent with the Joint Grooming Plan.
Party A shall outpulse the appropriate NPA, ATC Code, and Routing Code (operator
code) to Party B.

     7.3  TRANSIT SERVICE

          7.3.1  MFS shall exercise all reasonable efforts to enter into a 
reciprocal local traffic exchange arrangement (either via written agreement or 
mutual tariffs) with any wireless carrier, ITC, CLEC, or other LEC to which it 
sends, or from which it receives, local traffic that transits BA facilities over
Traffic Exchange Trunks. If MFS fails to enter into such an arrangement as 
quickly as commercially reasonable following the Effective Date and to provide 
copies thereof to BA, but continues to utilize BA's Transit Service for the 
exchange of local traffic with such wireless carrier, ITC, CLEC, or other LEC, 
MFS shall, in addition to paying the rate set forth in Exhibit A for said 
Transit Service, pay BA any charges or costs such terminating third party 
carrier imposes or levies on BA for the delivery or termination of such Traffic,
including any switched access charges, plus all reasonable expenses incurred by 
                                       ----
BA in delivering or terminating such Traffic and/or resulting from MFS's failure
to secure said reciprocal local traffic exchange arrangement. BA will, upon 
request, provide MFS with all reasonable cooperation and assistance in obtaining
such arrangements. The Parties agree to work cooperatively in appropriate 
industry fora to promote the adoption of reasonable industry guidelines relating
to Transit Traffic.

          7.3.2  Meet-Point Billing compensation arrangements as described in 
subsection 6.3 shall be utilized for compensation for the joint handling of Toll
Traffic.

          7.3.3  BA expects that most networks involved in Transit Traffic will 
deliver each call to each involved network with CCS and the appropriate 
Transactional Capabilities Application Part ("TCAP") message to facilitate full 
interoperability of those services supported by BA and billing functions. In all
cases, each Party shall follow the Exchange Message Record ("EMR") standard and 
exchange records between the Parties and with the terminating carrier to 
facilitate the billing process to the original network.

          7.3.4  Transit Traffic shall be routed over the Traffic Exchange 
Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

                                      24

<PAGE>
 
          7.4.1   MFS will interconnect to the BA 911 E911 selective routers or 
911 Tandem Offices, where available, which serve the areas in which MFS provides
Telephone Exchange Services, for the provision of 911 E911 services and for 
access to all subtending Public Safety Answering Points ("PSAP"). In such 
situations, BA will provide MFS with the appropriate CLLI codes and 
specifications of the Tandem Office serving area. In areas where E911 is not 
available, MFS and BA will negotiate arrangements to connect MFS to the 911 
service.

          7.4.2   Path and route diverse interconnections for 911 E911 shall be 
made at the M-IP, the BA-IP, or other points as necessary and mutually agreed, 
and as required by law or regulation.

          7.4.3   Upon request, BA will provide MFS with the following:

          (a)     an electronic interface, when available, through which MFS
     shall input and provide a daily update of 911/E911 database information
     related to appropriate MFS Customers. Until such time as an electronic
     interface is available, MFS shall provide BA with all appropriate 911
     information such as name, address, and telephone number in writing for BA's
     entry into the 911 database system. Any 911-related data exchanged between
     the Parties shall conform to the National Emergency Number Association
     standards:

          (b)     a file containing the Master Street Address Guide ("MSAG"), as
     may be updated from time to time, for the exchanges or communities
     specified;

          (c)     a return of any MFS E911 data entry files containing errors, 
     so that MFS may ensure the accuracy of the Customer records; and

          (d)     PSAP 911 Tandem information.

          7.4.4   In cases where a Customer of one Party elects to discontinue
     its service and become the Customer of the other Party ("Party B") but
     desires to retain its original telephone number pursuant to an INP or PNP
     arrangement, Party B will outpulse the telephone number to which the call
     has been forwarded (i.e. the Customer's ANI) to the 911 Tandem Office.
                         - -
     Party B will also provide the 911 database with both the forwarded number
     and the directory number, as well as the appropriate address information of
     the Customer.

          7.4.5   BA and MFS will use their best efforts to facilitate the
     prompt, robust, reliable and efficient interconnection of MFS systems to
     the 911/E911 platforms.

          7.4.6   BA and MFS will work cooperatively to arrange meetings with 
PSAPs to answer any technical questions the PSAPs, or county or municipal 
coordinators may have regarding the 911/E911 arrangements. BA shall assist MFS 
in identifying the appropriate person in each municipality for the purpose of 
obtaining the ten-digit subscriber number of each PSAP.

                                      25

<PAGE>
 
          7.4.7   The Parties acknowledge that the provision of INP, until PNP 
with full 911 compatability is available, creates a special need to have the 
Automatic Location Identification ("ALI") screen reflect two number: the "old" 
number and the "new" number assigned by MFS. The Parties acknowledge further the
objective of including the five character Telephone Company Identification 
("TCI") of the company that provides service to the calling line as part of the 
ALI display. Until such time as TCI is operational, however, BA and MFS agree to
supply and use the three-letter Access Carrier Name Abbreviation ("ACNA") as the
carrier identifier.

          7.4.8   MFS will compensate BA for connections to its 911/E911 
pursuant to Exhibit A.

          7.4.9   MFS will comply with all applicable rules and regulations 
pertaining to the provision of 911/E911 services in Virginia.

     7.5  ANCILLARY TRAFFIC GENERALLY  Ancillary Traffic that may be terminated
at a BA Local Serving Wire Center pursuant to subsection 4.5 above shall be 
subject to a separate transport charge for transport from the Local Serving Wire
Center to the appropriate Tandem Office, as set forth in Exhibit A.


8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise 
adversely affect in any manner either Party's right to employ or to request and 
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code 
Assignment Guidelines, as may be amended from time to time, or to establish, by 
Tariff or otherwise, Rate Centers and Rating Points corresponding to such NXX 
codes. Until such time as number administration is provided by a third party, BA
shall provide MFS access to telephone numbers by assigning NXX codes to MFS in 
accordance with such Assignment Guidelines.


     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing 
Guide ("LERG") in order to recognize and route traffic to the other Party's 
assigned NXX codes at all times. Neither Party shall impose any fees or charges 
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, MFS shall 
adopt the Rate Center Areas and Rate Center Points that the Commission has 
approved for BA, in all areas where BA and MFS service areas overlap, and MFS 
shall assign whole NPA-NXX codes to each Rate Center unless the LEC industry 
adopts alternative methods of utilizing NXX in the manner adopted by the NANP.

                                      26

<PAGE>
 
     8.4  MFS will also designate a Routing Point for each assigned NXX code. 
MFS shall designate one location for each Rate Center Area as the Routing Point 
for the NPA-NXXs associated with that Area, and such Routing Point shall be 
within the same LATA as the Rate Center Area but not necessarily within the Rate
Center Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in 
this Agreement is intended to, and nothing in this Agreement shall be construed 
to, in any way constrain MFS's choices regarding the size of the local calling 
area(s) that MFS may establish for its Customers, which local calling areas may 
be larger than, smaller than, or identical to, BA's local calling areas.


9.0  NETWORK MAINTENANCE AND MANAGEMENT: OUTAGES

     9.1  The Parties will work cooperatively to install and maintain a reliable
network. MFS and BA will exchange appropriate information (e.g., maintenance 
                                                           - -
contact numbers, network information, information required to comply with law 
enforcement and other security agencies of the Government) to achieve this 
desired reliability. In addition, the Parties will work cooperatively to apply 
sound network management principles to alleviate or to prevent congestion.

     9.2  Each Party recognizes a responsibility to follow the standards that 
may be agreed to between the Parties and to employ characteristics and methods 
of operation that will not interfere with or impair the service or any 
facilities of the other or any third parties connected with or involved directly
in the network of the other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Party A reasonably determines that the characteristics and methods of 
operation used by Party B will or may interfere with or impair its provision of 
services. Party A shall have the right to discontinue Interconnection subject, 
however, to the following:

          9.3.1  Party A shall have given Party B ten (10) days' prior written 
notice of interference or impairment or potential interference or impairment 
which specifies the time within which Party B is to correct the condition; and,

          9.3.2  Party A shall have concurrently provided a copy of the notice 
provided to Party B under (a) above to the appropriate federal and/or state 
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall 
not be required in emergencies and Party A may immediately discontinue 
Interconnection if reasonably necessary to meet its obligations. In such case, 
however, Party A shall use all reasonable means to notify Party B and the 
appropriate federal and or state regulatory bodies.

                                      27

<PAGE>
 
          9.3.4     Upon correction of the interference or impairment, Party A 
will promptly renew the Interconnection. During such period of discontinuance, 
there will be no compensation or credit allowance by Party A to Party B for 
interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

          9.4.1     The Interconnection provided hereunder may be discontinued
by either Party upon thirty (30) days written notice to the other for repeated
or willful violation of and/or a refusal to comply with this Agreement. The
Party discontinuing will notify the appropriate federal and/or state regulatory
bodies concurrently with the notice to the other Party of the prospective
discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or 
service being provided by a Party hereunder, the providing Party will follow 
procedures for isolating and clearing the outage or trouble that are no less 
favorable than those that apply to comparable arrangements, facilities, or 
services being provided by the providing Party to any other carrier whose 
network is connected to that of the providing Party. MFS and BA may agree to 
modify those procedures from time to time based on their experience with 
comparable Interconnection arrangements with other carriers.

     9.6  NOTICE OF CHANGES--SECTION 251(C)(5).

     If a Party makes a change in its network which it believes will materially 
affect the interoperability of its network with the other Party's network, the 
Party making the change shall provide at least ninety (90) days advance written 
notice of such change to the other Party.

10.  JOINT NETWORK RECONFIGURATION AND GROOMING PLAN; AND INSTALLATION, 
MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK RECONFIGURATION AND GROOMING PLAN. On or before December
1, 1996, unless the Parties agree to a different date, MFS and BA shall jointly 
develop a grooming plan (the "Joint Plan") which shall define and detail, inter 
                                                                          -----
alia.
- ----

          (a)  modifications to the agreement on physical architecture 
     consistent with the guidelines defined in Section 4;

          (b)  standards to ensure that Interconnection trunk groups experience 
a grade of service, availability and quality which is comparable to that 
achieved on interoffice trunks within BA's network and in accord with all 
appropriate relevant industry-accepted quality, reliability and availability 
standards. Trunks provided by either Party for Interconnection services will be 
engineered using a design blocking objective of B.01;

                                      28
<PAGE>
 
             (c)  the respective duties and responsibilities of the Parties with
     respect to the administration and maintenance of the trunk groups,
     including, but not limited to, standards and procedures for notification
     and discoveries of trunk disconnects;

             (d)  disaster recovery provision escalations;

             (e)  migration from one-way to two-way Interconnection Trunks upon 
     mutual agreement of the Parties;

             (f)  actual meet point locations on the SONET system; and

             (g)  such other matters as the Parties may agree.

     10.2    INSTALLATION, MAINTENANCE, TESTING AND REPAIR. BA's standard 
intervals for Feature Group D Switched Exchange Access Services will be used for
Interconnection. MFS shall meet the same intervals for comparable installations,
maintenance, joint testing, and repair of its facilities and services associated
with or used in conjunction with Interconnection or shall notify BA of its 
inability to do so and will negotiate such intervals in good faith. The Parties 
agree that the standards to be used by each Party for isolating and clearing any
disconnections and/or other outages or troubles shall be no less favorable than 
those applicable to comparable arrangements, facilities, or services being 
provided by such Party to any other carrier whose network is connected to that 
of the providing Party.

     10.3    FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING. Within sixty (60) 
days of executing this Agreement, MFS shall provide BA a one (1) year traffic 
forecast. This initial forecast will provide the amount of traffic to be 
delivered to each of BA's End Offices affected by the exchange of traffic. The 
forecast shall be updated and provided to BA on a quarterly basis, and include 
Access Carrier Terminal Location (ACTL), traffic type (local/toll, operator 
services, 911, etc.), code (identifies trunk group), A location/Z location (CLLI
codes), interface type (e.g., DS1), and trunks in service each year
(cumulative).

             10.3.1    Initial Forecasts/Trunking Requirements. Because BA's
                       ---------------------------------------
trunking requirements will, at least during an initial period, be dependent on 
the customer segments and service segments within customer segments to whom MFS 
decides to market its services. BA will be largely dependent on MFS to provide 
accurate trunk forecasts for both inbound (from BA) and outbound (from MFS) 
traffic. BA will, as an initial matter and upon request, provide the same number
of trunks to terminate local traffic to MFS as MFS provides to terminate local 
traffic to BA, unless MFS expressly identifies particular situations that are 
expected to produce traffic that is substantially skewed in either the inbound
or outbound direction, in which case BA will provide the number of trunks MFS
suggests. Upon the establishment of any new set of trunks for traffic from BA to
MFS, BA will monitor traffic for ninety (90) days, and will, as necessary at the
end of that period, either augment trunks or disconnect trunks, based on the
application of reasonable engineering criteria to the actual traffic volume
experienced. If, after such 90-day period, BA has determined that the trunks are
not warranted by actual traffic volumes, then, on ten (10) days' written notice,
BA may hold MFS financially responsible for

                                      29



 
<PAGE>
 
such trunks retroactive to the start of the 90-day period until such time as
they are justified by actual traffic volumes, based on the application of
reasonable engineering criteria. To the extent that BA requires MFS to install
trunks for delivery of traffic to BA. MFS may apply the same procedures with
respect to BA's trunking requirements.

11.0 UNBUNDLED ACCESS -- SECTION 251(C)(3).

     To the extent required of each Party by Section 251 of the Act, each Party 
shall offer to the other Party nondiscriminatory access to Network Elements on 
an unbundled basis at any technically feasible point. BA shall unbundle and 
separately price and offer Network Elements such that MFS will be able to lease 
and interconnect to whichever of the Network Elements MFS requires, and to 
combine the BA-provided elements with any facilities and services that MFS may 
itself provide, except that MFS shall not recombine Network Elements purchased 
from BA for use as a substitute for the purchase at wholesale rates of 
Telecommunications Services that BA provides unless otherwise mandated by the 
FCC or the Commission or agreed to by BA with other carriers.

     11.1 UNBUNDLED LOCAL LOOP ("ULL") TRANSMISSION TYPES

     Subject to subsection 11.4, BA shall allow MFS to access the following ULL 
types (in addition to those ULLs available under applicable tariffs) unbundled 
from local switching and local transport in accordance with the terms and 
conditions set forth in this subsection 11.1.

          11.1.1    "2-Wire Analog Voice Grade ULL" or "Analog 2W" provides an 
effective 2-wire channel with 2-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals and 
loop-start signaling. The service is more fully described in Bell Atlantic 
TR-72565. If "Customer-Specified Signaling" is requested, the service will 
operate with one of the following signaling types that may be specified when the
service is ordered: loop-start, ground-start, loop-reverse-battery, and no 
signaling. The service is more fully described in Bell Atlantic TR-72570.

          11.1.2    "4-Wire Analog Voice Grade ULL" or "Analog 4W" provides an 
effective 4-wire channel with 4-wire interfaces at each end that is suitable for
the transport of analog voice grade (nominal 300 to 3000 Hz) signals. The
service will operate with one of the following signaling types that may be
specified when the service is ordered: loop-start, ground-start, loop-reverse-
battery, duplex, and no signaling. The service is more fully described in Bell
Atlantic TR-72570.

          11.1.3    "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" provides a 
channel with 2-wire interfaces at each end that is suitable for the transport of
160 kbps digital services using the ISDN 2B1Q line code.

          11.1.4    "2-Wire ADSL-Compatible ULL" or "ADSL 2W" provides a channel
with 2-wire interfaces at each end that is suitable for the transport of digital
signals up to 6 Mbps toward the Customer and up to 640 kbps from the Customer.
BA will offer ADSL-Compatible

                                      30
<PAGE>
 
ULLs only when the technology BA uses to provide such ULLs is compatible with 
that of MFS. In addition, ADSL-Compatible ULLs will be available only where 
existing copper facilities can meet applicable industry standards.

             11.1.5    "2-Wire HDSL-Compatible ULL" or "HDSL 2W" provides a
channel with 2-wire interfaces at each end that is suitable for the transport of
784 kbps digital signals simultaneously in both directions using the 2B1Q line
code. HDSL compatible ULLs will be available only where existing copper 
facilities can meet the specifications.

             11.1.6    "4-Wire HDSL-Compatible ULL" or "HDSL 4W" provides a
channel with 4-wire interfaces at each end. Each 2-wire channel is suitable for
the transport of 784 kbps digital signals simultaneously in both directions
using the 2B1Q line code. HDSL compatible ULLs will be available only where
existing copper facilities can meet the specifications.

             11.1.7    ULLs will be offered on the terms and conditions
specified herein and on such other terms in applicable Tariffs that are not
inconsistent with the terms and conditions set forth herein. BA shall make ULLs
available to MFS at the rates specified by the Commission, as amended from time
to time, subject to the provisions of subsection 11.1.8 below.

             11.1.8    BA will make Analog 2-Wire ULLs available for lease by
MFS in accordance with the schedule set forth in Schedule 3.0. BA will make BRI
ISDN and Analog 4W ULLs available for lease by MFS by the later of January 1,
1997, or the date when the ULL milestone contained in Schedule 3.0 is achieved
in the LATA. BA will make ADSL 2W, HDSL 2W, and HDSL 4W ULLs available for lease
by MFS as soon as practicable, but in any event no later than six months, after
BA makes the services using equivalent loop facilities commercially available to
its own end-user Customers in Virginia. Upon request by either BA or MFS, the
Parties shall agree upon a reasonable schedule and location for a technical and
operational trial(s) of ADSL 2W, HDSL 2W, and/or HDSL 4W ULLs. Such trial(s)
may, by mutual agreement, be conducted in any jurisdiction in which affiliates
of BA and MFS both operate. Upon successful completion of such trial(s), the
Parties shall agree upon an implementation schedule for the ULL type(s) subject
to such trial(s), which schedule shall begin no later than ninety (90) days
after successful completion of such trial(s).

     11.2    PORT TYPES

     BA shall make available to MFS unbundled 2-wire analog line and 2-wire 
analog trunk Ports on the terms and conditions specified herein and on such 
other terms in applicable Tariffs that are not inconsistent with the terms and 
conditions set forth herein. BA will offer MFS Ports utilizing other 
technologies as they become available, upon bona fide request by MFS.
                                            ---- ----

                                   31      
<PAGE>
 
     11.3    TRUNK SIDE LOCAL TRANSPORT

     BA shall provide MFS local transport from the trunk side of BA's Central 
Office Switches using private lines and special access services unbundled from 
switching and other services in accordance with the terms and conditions of BA's
existing or filed Tariffs, as referenced in Exhibit A.

     11.4    LIMITATIONS ON UNBUNDLED ACCESS

             11.4.1    Unless otherwise mandated by the FCC or the Commission or
agreed to by BA with other carriers, MFS may not cross-connect a BA-provided ULL
to a BA-provided Port, but instead shall purchase a network access line under 
applicable tariffs.

             11.4.2    BA shall only be required to make available ULLs and
Ports where such ULLs and Ports are available.

             11.4.3    MFS shall access BA's unbundled Network Elements
specifically identified in this Agreement via Collocation in accordance with 
Section 13 at the BA Wire Center where those elements exist and each ULL or Port
shall be delivered to MFS's Collocation by means of a Cross Connection.

             11.4.4    BA shall provide MFS access to its Unbundled Local Loops 
at each of BA's Wire Centers for loops terminating in that Wire Center. In 
addition, if MFS requests one or more ULLs provisioned via Integrated Digital 
Loop Carrier or Remote Switching technology deployed as a ULL concentrator, BA 
shall, where available, move the requested ULL(s) to a spare, existing physical 
ULL at no additional charge to MFS. If, however, no spare physical ULL is 
available, BA shall within three (3) business days of MFS's request notify MFS 
of the lack of available facilities. MFS may then at its discretion make a 
Network Element Bona Fide Request to BA to provide the Unbundled Local Loop 
through the demultiplexing of the integrated digitized ULL(s). MFS may also make
a Network Element Bona Fide Request for access to Unbundled Local Loops at the 
ULL concentration site point. Alternatively, MFS may choose to avail itself of 
BA's Special Construction services, as set forth in Exhibit A, for the 
provisioning of such ULL(s). Notwithstanding anything to the contrary in this 
Agreement, the provisioning intervals set forth in subsection 11.6 and the 
Performance Criteria and Performance Interval Dates set forth in subsection 27.1
and Schedule 27, respectively, shall not apply to ULLs provided under this 
subsection 11.4.4.

             11.4.5    If MFS orders a ULL type and the distance requested on 
such ULL exceeds the transmission characteristics in applicable technical 
references, distance extensions may be required and additional rates and charges
shall apply as set forth in Exhibit A or applicable Tariffs.

             11.4.6    BA will exercise all reasonable efforts to ensure that 
the service intervals that apply to ULLs and unbundled Ports are comparable to 
the (i) repair intervals that apply to the bundled dial tone line service, and 
(ii) installation intervals that apply to other BA

                                      32




 
<PAGE>
 
coordinated services, except as provided in Section 27. Although BA will make 
commercially reasonable efforts to ensure that ULLs and unbundled ports meet 
specified or agreed-upon technical standards. BA makes no warranty that the ULLs
or unbundled Ports supplied by BA hereunder will be compatible with the services
MFS may offer to its Customers if they are used in a manner not contemplated by 
the Parties.

     11.5    AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

             11.5.1    BA shall, upon request of MFS, and to the extent 
technically feasible, provide to MFS access to its Network Elements on an 
unbundled basis for the provision of MFS's Telecommunications Service. Any 
request by MFS for access to an BA Network Element that is not already available
shall be treated as a Network Element Bona Fide Request. MFS shall provide BA 
access to its Network Elements as mutually agreed by the Parties or as required 
by the Commission or FCC.

             11.5.2    A Network Element obtained by one Party from the other 
Party under this subsection 11.5 may be used in combination with the facilities 
of the requesting Party only to provide a Telecommunications Service, including 
obtaining billing and collection, transmission, and routing of the 
Telecommunications Service.

             11.5.3    Notwithstanding anything to the contrary in this 
subsection 11.5, a Party shall not be required to provide a proprietary Network 
Element to the other Party under this subsection 11.5 except as required by the 
Commission or FCC.

     11.6    PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to ULLs. These and other mutually agreed-upon 
procedures shall apply reciprocally for the "live" cutover of Customers from BA 
to MFS and from MFS to BA.

             11.6.1    Upon request by MFS, BA will apply the following 
coordination procedures to conversions of live Telephone Exchange Services to 
ULLs. Coordinated cutover charges will apply to any such arrangement, only to 
the extent provided by Section A.4.a of Exhibit A. If MFS elects not to request 
coordinated cutover, BA will process MFS's request in the normal course and 
subject to the normal installation intervals.

             11.6.2    MFS shall request ULLs from BA by delivering to BA a 
valid electronic transmittal service order (when available) or another mutually 
agreed-upon type of service order. Such service order shall be provided in 
accordance with industry format and specifications or such format and 
specifications as may be agreed to by the Parties. Within forty-eight (48) hours
of BA's receipt of such valid service order, BA shall provide MFS the firm order
commitment date according to the Performance Interval Dates as set forth in 
Schedule 27 by which the ULLs covered by such service order will be installed. 
In addition, BA shall provide MFS with the related ULL design information, if 
available, at least forty-eight (48) hours prior to the scheduled cutover time.

                                      33
<PAGE>
 
             11.6.3    On each ULL order in a Wire Center, MFS and BA will agree
on a cutover time at least forty-eight (48) hours before that cutover time. The 
cutover time will be defined as a 15-30 minute window within which both the MFS 
and BA personnel will make telephone contact to complete the cutover.

             11.6.4    Within the appointed 15-30 minute cutover time, the MFS 
person will call the BA organization designated to coordinate cross-connection 
work and when the BA organization is reached in that interval such work will be 
promptly performed.

             11.6.5    If MFS requires a change in scheduling, it must contact 
BA to issue a supplement to the original order. The negotiations process to 
determine the date and time of cutover will then be reinitiated as usual.

             11.6.6    If the MFS person is not ready within the appointed 
interval and if MFS had not called to reschedule the work at least two (2) hours
prior to the start of the interval, MFS shall be liable for the non-recurring 
charge for the unbundled elements scheduled for the missed appointment. In 
addition, non-recurring charges for the rescheduled appointment will apply.

             11.6.7    If BA is not available or not ready at any time during 
the appointed 15-30 minute interval, MFS and BA will reschedule and BA will 
waive the non-recurring charge for the unbundled elements originally scheduled 
for that interval, whenever those unbundled elements are actually cut over 
pursuant to an agreed-upon rescheduling.

             11.6.8    The standard time expected from disconnection of a live 
Telephone Exchange Service to the connection of the unbundled element to the MFS
Collocation Arrangement is fifteen (15) minutes per voice grade circuit for all 
orders consisting of fifteen (15) ULLs or less. Orders involving more than 
fifteen (15) ULLs will require a negotiated interval.

             11.6.9    If unusual or unexpected circumstances prolong or extend 
the time required to accomplish the coordinated cutover, the Party responsible 
for such circumstances is responsible for the reasonable labor charges of the 
other Party. Delays caused by the Customer are the responsibility of MFS.

             11.6.10   If MFS has ordered INP as part of an ULL installation, BA
will coordinate implementation of INP with the ULL installation. BA's provision 
of unbundled elements shall in all cases be subject to the availability of 
suitable facilities, to the extent permitted by Section 251 of the Act.

             11.6.11   If MFS requests or approves a BA technician to perform 
services on the network side of the Rate Demarcation Point beyond normal 
installation of the ULLs covered by the service order, BA may charge MFS for any
additional and reasonable labor charges to perform such services. BA may also 
charge MFS its normal overtime rates for services MFS requests to be performed 
outside of BA's normal business hours (M-F 9am to 5pm, E.S.T.).

                                      34
<PAGE>
 
         11.7    MAINTENANCE OF UNBUNDLED LOCAL LOOPS

         If (i) MFS reports to BA a Customer trouble, (ii) MFS requests a
dispatch, (iii) BA dispatches a technician, and (iv) such trouble was not caused
by BA's facilities or equipment, then MFS shall pay BA a per-trip charge charge
and labor charges per quarter hour increments for time associated with said
dispatch, as set forth in Exhibit A. In addition, this charge also applies in
situations when the Customer contact as designated by MFS is not available at
the appointed time. MFS accepts responsibility for initial trouble isolation and
providing BA appropriate dispatch information based on their test results. If,
as the result of MFS instructions, BA is erroneously requested to dispatch
within the Central Office, BA may levy on MFS an appropriate charge.

         11.8    RATES AND CHARGES

         BA shall charge the non-recurring and monthly recurring rates for
unbundled Local Loops and other Network Elements set forth in Exhibit A.

12.0     RESALE -- SECTIONS 251(C)(4) AND 251(B)(1).

         12.1    AVAILABILITY OF RETAIL RATES FOR RESALE

         Each Party shall make available its Telecommunications Services for 
resale at the retail rates set forth in its Tariffs to the other Party in 
accordance with Section 251(b)(1) of the Act. In addition, BA and MFS shall each
allow the resale by the other of all Telecommunications Services that are 
offered primarily or entirely to other Telecommunications Carriers (e.g., 
                                                                    - - 
Switched and special Exchange Access Services) at the rates already applicable 
to such services. BA shall also allow the resale by MFS of such other 
non-Telecommunications Services as BA, in its sole discretion, determines to 
provide for resale under terms and conditions to be agreed to by the Parties.

         12.2    AVAILABILITY OF WHOLESALE RATES FOR RESALE

         BA shall make available to MFS for resale all Telecommunications 
Services that BA provides at retail to Customers that are not Telecommunications
Carriers at the retail prices set forth in BA's Tariffs less the wholesale 
discount set forth in Exhibit A in accordance with Section 251(c)(4) of the Act.
Such services shall be provided in accordance with the terms of the applicable 
retail services Tariff(s), including, without limitation, user or user group 
restrictions, as the case may be, subject to the requirement that such 
restrictions shall in all cases comply with the requirements of Section 251 of 
the Act and the FCC Regulations regarding restrictions on resale. The Parties 
may also agree to negotiate term and or volume discounts for resold services.

         12.3    AVAILABILITY OF SUPPORT SERVICES AND BRANDING FOR RESALE 

                                      35
<PAGE>
 
     BA shall make available to MFS the various support services for resale 
described in Schedule 12.3 hereto in accordance with the terms set forth 
therein. In addition, to the extent required by Applicable Laws, upon request 
by MFS and at prices, terms and conditions to be negotiated by MFS and BA. BA 
shall provide BA Retail Telecommunications Services (as defined in Schedule 
12.3) that are identified by MFS's trade name, or that are not identified by 
trade name, trademark or service mark.

     12.4    ADDITIONAL TERMS GOVERNING RESALE AND USE OF BA SERVICES

             12.4.1    MFS shall comply with the provisions of this Agreement 
(including, but not limited to, all applicable BA Tariffs) regarding resale or 
use of BA services. In addition, MFS shall make reasonable efforts in good faith
to ensure that its Customers comply with the provisions of BA's Tariffs 
applicable to their use of BA's Telecommunications Services.

             12.4.2    Without in any way limiting subsection 12.4.1, MFS shall 
not resell (a) residential service to business or other nonresidential Customers
of MFS, (b) Lifeline or other means-tested service offerings, or grandfathered 
service offerings, to persons not eligible to subscribe to such service 
offerings from BA, or (c) any other BA service in violation of any user or user 
group restriction that may be contained in the BA Tariff applicable to such 
service to the extent such restriction is not prohibited by Applicable Laws. In 
addition, MFS shall be subject to the same limitations that BA's own retail 
Customers may be subject to with respect to any Telecommunications Service 
that BA may, in its discretion and to the extent not prohibited by Applicable 
Laws, discontinue offering. Except as otherwise provided by this Agreement or 
Applicable Laws, BA will give MFS notice in writing or electronically (which may
be by giving MFS access to a database or an Internet site that contains the 
applicable information, or by other electronic means) of material modification 
of the operation, or discontinuance, of BA Retail Telecommunications Services
(as defined in Schedule 12.3) furnished under this Agreement for resale at least
60 days prior to the time the material modification or discontinuance becomes 
effective.

             12.4.3    BA shall not be obligated to offer to MFS at a wholesale 
discount Telecommunications Services that BA offers at a special promotional 
rate if such promotions are for a limited duration of ninety (90) days or less.

             12.4.4    MFS shall provide to BA, in accordance with BA's Tariffs,
adequate assurance of payment of charges due to BA in connection with MFS's 
purchase of BA Telecommunications Services for resale. For the purposes of 
providing such adequate assurance of payment, MFS shall be deemed to be a 
business customer, even if MFS is purchasing Telecommunications Services for 
resale to residential customers.

             12.4.5    MFS shall not be eligible to participate in any BA plan 
or program under which BA end user retail Customers may obtain products or 
merchandise, or services which are not Bell Atlantic Retail Telecommunications 
Services (as defined in Schedule 12.3), in return for trying, agreeing to 
purchase, purchasing, or using Bell Atlantic Retail Telecommunications Services.

                                      36
<PAGE>
 
13.0    COLLOCATION -- SECTION 251(c)(6).

        13.1   BA shall offer to MFS Physical Collocation of equipment necessary
for Interconnection (pursuant to Section 4) or for access to unbundled Network
Elements (pursuant to Section 11.0), except that BA may offer only Virtual
Collocation if BA demonstrates to the Commission that Physical Collocation is
not practical for technical reasons or because of space limitations, as provided
in Section 251(c)(6) of the Act. BA shall provide such Collocation solely for
the purpose of Interconnection with facilities or services of BA or access to
unbundled Network Elements of BA, except as otherwise mutually agreed to in
writing by the Parties or as required by the FCC or the Commission, subject to
applicable federal and state Tariffs.

        13.2   Although not required to do so by Section 251(c)(6) of the Act,
by this Agreement, MFS agrees to offer to BA Collocation (at MFS's option either
Physical or Virtual) of equipment for purposes of Interconnection (pursuant to 
Section 4) on a non-discriminatory basis and at comparable rates, terms and 
conditions as MFS may provide to other third parties. MFS shall provide such 
Collocation subject to applicable Tariffs.

        13.3   Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for Physical Collocation for MFS. MFS may elect to
(i) retain its Virtual Collocation in that premises, and/or (ii) establish
Physical Collocation in that premises pursuant to current procedures and
applicable Tariffs. BA will not assess to MFS non-recurring charges for central
office common area construction to transition existing virtual collocation
arrangements to physical collocation arrangements in offices where MFS
previously paid such charges. BA will also waive cage construction charges for
cages of the same size originally paid for by MFS. MFS shall coordinate with BA
for rearrangement of MFS's equipment, facilities, and circuits. All applicable
Physical Collocation recurring charges shall apply.

        13.4   Where MFS is Virtually Collocated on the date hereof on a premise
that was initially prepared for MFS as Virtual Collocation. MFS may elect to (i)
retain its Virtual Collocation in that premises, or (ii) unless it is not 
practical for technical reasons or because of space limitations, convert its 
Virtual Collocation at such premises to Physical Collocation, in which case MFS 
shall coordinate the construction and rearrangement with BA of its equipment, 
facilities, and circuits, and for which MFS shall pay BA at applicable Tariff 
rates. In addition, all Physical Collocation recurring charges shall apply.

        13.5   For both Physical Collocation and Virtual Collocation, the 
Collocating Party shall provide its own or third-party leased transport 
facilities and terminate those transport facilities in equipment located in its 
Physical Collocation space, or in its virtually collocated equipment, at the 
Housing Party's premises as described in applicable Tariffs, and purchase Cross 
Connection to services or facilities as described in applicable Tariffs.

        13.6   Collocation shall occur under the terms of each Party's 
applicable and available Tariffs. Collocation is offered for network 
Interconnection between the Parties. Unless otherwise agreed to by the Parties 
or either Party is required by applicable law to permit on its collocated

                                      37
<PAGE>
 
premises, neither Party shall use a Collocation Arrangement to directly 
interconnect with a third party's equipment or facilities collocated at the same
location.

                           SECTION 251(B) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2).

     14.1 SCOPE

          14.1.1  The Parties shall provide Local Telephone Number Portability
("LTNP") on a reciprocal basis to each other to the extent technically feasible,
and in accordance with rules and regulations as from time to time prescribed by
the FCC and or the Commission.

          14.1.2  Until Permanent Number Portability is implemented by the 
industry pursuant to regulations issued by the FCC and/or the Commission, the 
Parties agree to reciprocally provide Interim Number Portability to each other 
at the prices listed in Exhibit A. Such agreed-upon prices for INP are not 
intended to reflect either Party's views on the cost recovery mechanisms being 
considered by the FCC in its current proceeding on number portability issues.

          14.1.3  Upon the agreement of the Parties or issuance of applicable 
FCC and/or Commission order(s) or regulations mandating the adoption of a 
Permanent Number Portability ("PNP") arrangement, BA and MFS will commence 
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as 
practically possible while minimizing interruption or degradation of service to 
their respective Customers. Once PNP is implemented, either Party may withdraw, 
at any time and at its sole discretion, its INP offerings, subject to advance 
notice to the other Party and coordination to allow the seamless and transparent
conversion of INP Customer numbers to PNP. Upon implementation of PNP pursuant 
to FCC or Commission regulation, both Parties agree to conform and provide such 
PNP. To the extent PNP rates or cost recovery mechanisms are not established by 
the applicable FCC or Commission order or regulation mandating the adoption of 
PNP, the Parties will negotiate in good faith the charges or cost recovery 
mechanism for PNP service at such time as a PNP arrangement is adopted by the 
Parties.

          14.1.4  Under either an INP or PNP arrangement, MFS and BA will 
implement a process to coordinate LTNP cutovers with ULL conversions (as 
described in Section 11 of this Agreement).

     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     MFS and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1  A Customer of one Party ("Party A") elects to become a 
Customer of the other Party ("Party B"). The Customer elects to utilize the 
original telephone number(s)

                                      38
<PAGE>
 
corresponding to the Telephone Exchange Service(s) it previously received from 
Party A, in conjunction with the Telephone Exchange Service(s) it will now 
receive from Party B. Upon receipt of a service order from Party B requesting 
assignment of the number(s) to Party B. Party A will implement an arrangement 
whereby all calls to the original telephone number(s) will be forwarded to a new
telephone number(s) designated by Party B, only within the same Exchange Area as
the original telephone number(s). Party A will route the forwarded traffic to 
Party B over the appropriate traffic exchange trunk groups.

          14.2.2 Party B will become the customer of record for the original 
Party A telephone number(s) subject to the INP arrangements. Upon the execution 
of an appropriate billing services agreement or such other mutually agreed-upon 
arrangement between the Parties. Party A shall use its reasonable efforts to 
consolidate into as few billing statements as possible collect, calling card, 
and third-number billed calls associated with the number(s), with sub-account 
detail by retained number.

          14.2.3 Party A will update its Line Information Database ("LIDB") 
listings for retained numbers, and restrict or cancel calling cards associated 
with those forwarded numbers as directed by Party B. In addition, Party A  will 
update the retained numbers in the LIDB with the screening options provided by 
Party B on a per order basis. Party B shall determine which of the screening 
options offered by Party A should apply to the Party B Customer account.

          14.2.4 Party B will outpulse the telephone number to which the call 
has been forwarded to the 911 Tandem Office. Party B will also provide the 911 
database with both the forwarded number and the directory number, as well as 
the appropriate address information of the Customer.

          14.2.5 Party A shall be permitted to cancel INP arrangements and 
reassign the telephone number(s) upon receipt of notification from Party B or a
third party that is authorized to act on behalf of the Customer. Party A shall
provide notification to Party B of third party orders affecting the INP service
of a Party B customer. The Parties agree to work cooperatively to develop
procedures or adopt industry standards or practices concerning the initiation
and termination of INP services in a multi-carrier environment.

          14.2.6 The INP service offered herein shall not initially apply to NXX
Codes 555, 915, 976, or 950, or for Feature Group A or coin telephone service. 
Upon request of either Party, provision of INP to these services will be 
mutually negotiated between the parties and provided to the extent feasible 
under negotiated rates, terms and conditions. INP shall not apply for any 
arrangement that would render the forwarded call Toll Traffic.

          14.2.7 The ordering of INP arrangements and the exchange of screening 
information shall be made in accordance with industry-accepted (e.g. OBF 
                                                                - - 
developed) format and specifications to the extent they have been implemented by
the Parties.

                                      39
<PAGE>
 
     14.3 PROCEDURES FOR PROVIDING INP THROUGH DIRECT INWARD DIAL TRUNKS 
(FLEX-DID)  Either Party may also request INP through Direct Inward Dial Trunks 
pursuant to any applicable Tariffs.

     14.4 PROCEDURES FOR PROVIDING LTNP THROUGH FULL NXX CODE MIGRATION  Where 
either Party has activated an entire NXX for a single Customer, or activated a 
substantial portion of an NXX for a single Customer, with the remaining numbers 
in that NXX either reserved for future use by that Customer or otherwise unused,
if such Customer chooses to receive Telephone Exchange Service from the other 
Party, the first Party shall cooperate with the second Party to have the entire 
NXX reassigned in the LERG (and associated industry databases, routing tables, 
etc.) to an End Office operated by the second Party. Such transfer will be 
accomplished with appropriate coordination between the Parties and subject to 
appropriate industry lead-times for movements of NXXs from one switch to 
another. Neither Party shall charge the other in connection with this 
coordinated transfer.

     14.5 RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described 
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed 
numbers should be received by each Customer's chosen LEC as if each call to the 
Customer had been originally addressed by the caller to a telephone number 
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to 
accomplish this objective where INP is employed, the Parties shall utilize the 
process set forth in this subsection 14.5 whereby terminating compensation on 
calls subject to INP will be passed from the Party (the "Performing Party") 
which performs the INP to the other Party (the "Receiving Party") for whose 
Customer the INP is provided.

          14.5.1  The Parties shall individually and collectively make best 
efforts to track and quantify INP traffic between their networks based on the 
CPN of each call by identifying CPNs which are INP'ed numbers. The Receiving 
Party shall charge the Performing Party for each minute of INP traffic at the 
INP Traffic Rate specified in subsection 14.5.3 in lieu of any other 
compensation charges for terminating such traffic, except as provided in 
subsection 14.5.2.

          14.5.2  By the Interconnection Activation Date in each LATA, the 
Parties shall jointly estimate for the prospective six months, based on historic
data of all traffic in the LATA, the percentages of such traffic that, if dialed
to telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal 
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra 
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as 
Transit Traffic. On the date which is six (6) months after the Interconnection 
Activation Date, and thereafter on each succeeding six month anniversary of such
Interconnection Activation Date, the Parties shall establish new INP traffic 
percentages to be applied in the prospective six (6) month period, based on the 
Performing Party's choice of actual INP traffic percentages from the preceding
six (6) month period or historic data of all traffic in the LATA.

          14.5.3  The INP Traffic Rate shall be equal to the sum of:

                                      40
<PAGE>
 
  (Recip Traffic percentage times the Reciprocal Compensation Rate set forth 
                            -----
in Exhibit A)
                                     plus
                                     ----

     (Intra Traffic percentage times Receiving Party's effective intrastate FGD
                               -----
rates)
                                     plus
                                     ----

     (Inter Traffic percentage times Receiving Party's effective interstate FGD
                               -----
rates).

     The Receiving Party shall compensate the Performing Party for its billing
and collection of charges for the intrastate and interstate FGD access services
provided by the Receiving Party to a third party through the greater of (i) the
difference between the intrastate and interstate FGD rates of the Receiving
Party and the Performing Party, or (ii) three percent (3%) of the Performing
Party's intrastate and interstate FGD revenues for INP'ed numbers. Under no
circumstances shall the Performing Party, in performing the billing and
collections service on behalf of the Receiving Party, be obligated to pass
through more than ninety seven percent (97%) of its FGD access charge to the
Receiving Party in connection with any given INP'ed call.

     1.46      RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this Section 14, in 
light of the FCC's First Report and Order and Further Notice of Proposed 
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the 
Parties stipulate and agree as follows:

               14.6.1    The rates listed in Exhibit A for the provision of INP 
are appropriate amounts that each Party providing INP service should recover for
the provision of those INP functionalities in BA's operating territory. For the 
INP functions it provides, each Party should be allowed to recover these amounts
in a manner consistent with any final FCC and/or Commission order on INP cost 
recovery (such as a state-wide fund contributed to by all telecommunications 
carriers).

               14.6.2    Within three (3) weeks of the Effective Date, the 
Parties will jointly seek a Commission proceeding and ruling to develop and 
implement an INP cost recovery mechanism consistent with the policy described 
in the Order and/or any subsequent FCC or Commission decision.

               14.6.3    Until such time as a final FCC and/or Commission order,
pursuant to subsection 14.6.2 above, is implemented, each Party will provide INP
service to the other Party at the INP rates listed in Exhibit A. All revenues
received by the providing Party from its provision of INP service to the other
Party shall be placed into an escrow fund maintained by or tracked separately by
the providing Party. Upon issuance of a final FCC and/or Commission order, and
to the extent that it permits the Party providing INP to recover the associated
costs from a state-wide fund, the providing Party shall refund to the purchasing
Party an amount equal to the amount it recovers from such fund for its provision
of INP service to the purchasing Party from the Effective Date, provided that in
no event shall the refund amount exceed the aggregate amount the providing Party
has received from the purchasing Party's INP services. If no such

                                      41
<PAGE>
 
fund is ordered or established, the providing Party shall retain the full amount
of the revenues tracked or held in escrow by it pursuant to this subsection 
14.6.3.

          14.6.4  The Parties agree that neither Party waives its rights to 
advocate its views that are consistent with this subsection 14.6 on the 
appropriate INP cost recovery mechanism, or to present such views before any 
relevant regulatory body or other agency as they relate to FCC or Commission 
actions on INP cost recovery.

15.0 DIALING PARITY -- SECTION 251(B)(3).

     BA and MFS shall each provide the other with nondiscriminatory access 
to such services and information as are necessary to allow the other Party to 
implement dialing parity for Telephone Exchange Service, operator services, 
directory assistance, and directory listing information with no unreasonable 
dialing delays, as required under Section 251(b)(3) of the Act.

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(B)(4).

     Each Party shall provide the other Party access to its poles, ducts, 
rights-of-way and conduits it owns or controls in conformance with 47 U.S.C. 
(S) 224, as set forth in Exhibit A, where facilities are available, on terms, 
conditions and prices comparable to those offered to any other entity pursuant 
to each Party's applicable Tariffs. Where no such Tariffs exist, such access 
shall be provided in accordance with the requirements of 47 U.S.C. (S) 224, 
including any FCC regulations that may be issued. In addition, the Parties agree
to review any existing rights-of-way arrangements between them in order to bring
such arrangements into conformance with the requirements of 47 U.S.C. (S) 224 
within ninety (90) days of the date hereof. In conducting such review and making
the necessary conforming changes, if any, the Parties agree to consider the 
appropriateness of applying such changes on a retroactive basis to the date 
hereof. If the Parties are unable to agree on the necessary changes to the 
existing arrangements or the appropriateness of applying them on a retroactive 
basis, the Parties may invoke the procedures set forth in subsection 29.9 below.


17.0 DATABASES AND SIGNALING.

     17.1 Each Party shall provide the other Party with access to databases and
associated signaling necessary for call routing and completion by providing SS7
Common Channel Signaling (CCS) Interconnection in accordance with existing
Tariffs, and Interconnection and access to 800/888 databases. LIDB, and any
other necessary databases in accordance with existing Tariffs and/or agreements
with other unaffiliated carriers, as set forth in the Exhibit A. Alternatively,
either Party may secure CCS Interconnection from a commercial SS7 hub provider,
and in that case the other Party will permit the purchasing Party to access the
same databases as would have been accessible if the purchasing party had
connected directly to the other Party's CCS network.

                                      42
<PAGE>
 
       17.2    The Parties will provide CCS Signaling to one another, where and
as available, in conjunction with all Local Traffic, Toll Traffic, Meet Point
Billing Traffic, and Transit Traffic. The Parties will cooperate on the exchange
of TCAP messages to facilitate interoperability of CCS-based features between
their respective networks, including all CLASS features and functions, to the
extent each Party offers such features and functions to its Customers. All CCS
Signaling parameters will be provided upon request (where available), including
called party number, calling party number, originating line information, calling
party category, and charge number. All privacy indicators will be honored. The
Parties will follow all Ordering and Billing Forum-adopted standards pertaining
to CIC/OZZ codes. Where CCS Signaling is not available, in-band multi-frequency
(MF) wink start signaling will be provided. Any such MF arrangement will require
a separate local trunk circuit between the Parties' respective switches. In such
an arrangement, each Party will outpulse the full ten-digit telephone number of
the called party to the other Party.

       17.3    Each Party shall provide trunk groups, where available and upon
reasonable request, that are configured utilizing the B8ZS & ESF protocol for 64
kbps clear channel transmission to allow for ISDN interoperability between the
Parties' respective networks.

       17.4    The following publications describe the practices, procedures and
specifications generally utilized by BA for signaling purposes and is listed
herein to assist the Parties in meeting their respective Interconnection
responsibilities related to Signaling:

               (a)  Bellcore Special Report SR-TSV-002275. BOC Notes on the LEC
Networks - Signaling; and

               (b)  Bell Atlantic Supplement Common Channel Signaling Network
Interface Specification (BA-905).

       17.5    Each Party shall charge the other Party mutual and reciprocal
rates for CCS Signaling as follows: BA shall charge MFS in accordance with
Exhibit A hereto and applicable Tariffs; MFS shall charge BA rates equal to the
rates BA charges MFS, unless MFS's Tariffs for CCS signaling provide for lower
generally available rates, in which case MFS shall charge BA such lower rates.

18.0   COORDINATED SERVICE ARRANGEMENTS.

       18.1    INTERCEPT AND REFERRAL ANNOUNCEMENTS. When a Customer changes its
service provider from BA to MFS, or from MFS to BA, and does not retain its
original telephone number, the Party formerly providing service to such Customer
shall provide a referral announcement ("Referral Announcement") on the abandoned
telephone number which provides details on the Customer's new number or provide
other appropriate information to the extent known. Referral Announcements shall
be provided reciprocally, free of charge to either the other Party or the
Customer to the extent the providing Party does not charge its own customers for

                                      43
<PAGE>
 
such service, for a period of not less than four (4) months after the date the 
Customer changes its telephone number in the case of business Customers and not 
less than sixty (60) days after the date the Customer changes its telephone 
number in the case of residential Customers. However, if either Party provides 
Referral Announcements for different periods than the above respective periods 
when its Customers change their telephone numbers, such Party shall provide the 
same level of service to Customers of the other Party.

      18.2   COORDINATED REPAIR CALLS. MFS and BA will employ the following 
procedures for handling misdirected repair calls:

             18.2.1   MFS and BA will educate their respective Customers as to
the correct telephone numbers to call in order to access their respective repair
bureaus.

             18.2.2   To the extent Party A is identifiable as the correct
provider of service to Customers that make misdirected repair calls to Party B,
Party B will immediately refer the Customers to the telephone number provided by
Party A, or to an information source that can provide the telephone number of
Party A, in a courteous manner and at no charge. In responding to misdirected
repair calls, neither Party shall make disparaging remarks about the other
Party, its services, rates, or service quality.
           
             18.2.3   MFS and BA will provide their respective repair contact
numbers to one another on a reciprocal basis.

      18.3   CUSTOMER AUTHORIZATION. In order for either Party to order or
terminate service on behalf of the other Party's Customer, the requesting Party
must have proper written authorization from the customer in its files, and
provide a copy of such authorization to the other Party upon request. In the
event the requesting Party (i) fails to provide a copy of the Customer's proper
written authorization upon request, (ii) requests changes in the other Party's
Customer's service without having such authorization in it files, or (iii)
mistakenly changes the other Party's Customer's service, the requesting Party
shall be liable to the other Party for all charges that would be applicable to
the Customer for restoring service to the other Party.

19.0  DIRECTORY SERVICES ARRANGEMENTS 

      BA will, upon request, provide the following directory services to MFS in
accordance with the terms set forth herein. In this Section 19, references to a
MFS Customer's "primary listing" shall mean such Customer's name, address, and
main telephone number, which number falls within the NXX codes directly assigned
to MFS or is retained by MFS on the Customer's behalf pursuant to LTNP 
arrangements with BA or any other carrier within the geographic area covered in 
the relevant BA directory.

      19.1 DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

                                      44




           
<PAGE>
 
          19.1.1  BA will include the MFS Customer's primary listing in its
"White Pages" directory (residence and business listings) and "Yellow Pages"
directory (business listings) that cover the address of the Customer. Listings
of MFS's Customers will be interfiled with listings of BA's Customers and the
Customers of other LECs included in the BA directories. MFS will pay BA a non-
recurring charge as set forth in Exhibit A for providing such service for each
MFS Customer's primary listing. MFS will also pay BA's Tariffed charges, as the
case may be, for additional and foreign white page listings and other white
pages services for MFS's Customers. BA will not require a minimum number of
listings per order.

          19.1.2  BA will also include the MFS Customer's primary listing in
BA's directory assistance database on the same basis that BA's own Customers are
included, as well as in any electronic directories in which BA's Customers are
ordinarily included, for no charge other than the charges identified in
subsection 19.1.1.

          19.1.3  BA will distribute to MFS Customers copies of their primary
white pages and yellow pages directories at the same time and on the same basis
that BA distributes primary directories to its own Customers. BA will also
deliver a reasonable number of such directories to MFS. These distributions will
be made for no additional charge. MFS and its Customers may request additional
directories from BA's Directory Fulfillment Centers, which Centers will provide
such additional directories for the same charges applicable to comparable
requests by BA Customers.

          19.1.4  BA will include all MFS NXX codes associated with the areas to
which each directory pertains, along with BA's own NXX codes in any maps or
lists of such codes which are contained in the general reference portions of the
directories. MFS's NXX codes shall appear in such maps or lists in the same
manner as BA's NXX information.

          19.1.5  MFS shall provide BA with daily listing information on all new
MFS Customers in the format required by BA or a mutually-agreed upon industry
standard format. The information shall include the Customer's name, address,
telephone number, the delivery address and number of directories to be
delivered, and, in the case of a business listing, the primary business heading
under which the business Customer desires to be placed, and any other
information necessary for the publication and delivery of directories. MFS will
also provide BA with daily listing information showing Customers that have
disconnected or terminated their service with MFS. BA will provide MFS with
confirmation of listing order activity within forty eight (48) hours.

          19.1.6  BA will accord MFS's directory listing information the same
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to MFS's directory listing information will be
used solely for the purpose of providing directory services; provided, however,
that BA may use or license information contained in its directory listings for
direct marketing purposes so long as the MFS Customers are not separately
identified as such; and provided further that MFS may identify those of its
Customers that request that their names not be sold for direct marketing
purposes, and BA will honor such requests to the same extent as it does for its
own Customers.

                                      45
<PAGE>
 
           19.1.7  BA or BA's publisher shall provide MFS with a report of all
MFS Customer listings ninety (90) days prior to directory publication in such
form and format as may be mutually agreed to by both Parties. Both Parties
shall use their best efforts to ensure the accurate listing of such information.
BA will also provide MFS, upon request, a copy of the BA listings standards
and specifications manual. In addition, BA will provide MFS with a listing of
Yellow Pages headings and directory close schedules on an ongoing basis.

           19.1.8  MFS will adhere to all practices, standards, and ethical
requirements of BA with regard to listings, and, by providing BA with listing
information, warrants to BA that MFS has the right to place such listings on
behalf of its Customers. MFS agrees that it will undertake commercially
practicable and reasonable steps to attempt to ensure that any business or
person to be listed is authorized and has the right (i) to provide the product
or service offered, and (ii) to use any personal or corporate name, trade name
or language used in the listing.

           19.1.9  BA's liability to MFS in the event of a BA error in or
omission of a listing shall be subject to the same limitations that BA's
liability to its own Customers are subject to. In addition, MFS agrees to
take, with respect to its own Customers, all reasonable steps to ensure that its
and BA's liability to MFS's Customers in the event of a BA error in or omission
of a listing shall be subject to the same limitations that BA's liability to its
own Customers are subject to.

     19.2  YELLOW PAGE MAINTENANCE. The Parties agree to work cooperatively
to ensure that Yellow Page advertisements purchased by Customers that switch
their service to MFS (including Customers utilizing MFS-assigned telephone
numbers and MFS Customers utilizing LTNP) are maintained without interruption.
BA will allow MFS Customers to purchase new Yellow Pages advertisements without
discrimination, under the identical rates, terms and conditions as apply to BA's
Customers. BA and MFS may implement a commission program whereby MFS may, at
MFS's sole discretion, act as a sales, billing and collection agent for Yellow
Pages advertisements purchased by MFS's Telephone Exchange Service Customers.

     19.3  SERVICE INFORMATION PAGES. BA will include in the "Customer Guide" or
comparable section of the applicable white pages directories listings provided
by MFS for MFS's installation, repair and customer service and other essential
service oriented information, as agreed by the Parties, including appropriate
identifying logo. Such listings shall appear in the manner agreed to by the
Parties. BA shall not charge MFS for inclusion of this essential service-
oriented information, but reserves the right to impose charges on other
information MFS may elect to submit and BA may elect to accept for inclusion in
BA's white pages directories. BA will provide MFS with the annual directory
close dates and reasonable notice of any changes in said dates.

     19.4  DIRECTORY ASSISTANCE (DA); CALL COMPLETION

           19.4.1  Upon request, BA will provide MFS with directory assistance
and/or call completion services substantially in accordance with the terms set
forth in the form Directory Assistance and Call Completion Services Agreement
appended hereto as Exhibit C.

                                      46
<PAGE>
 
               19.4.2    Also upon request, BA will provide to MFS operator
services trunk groups, utilizing Feature Group D type signaling, with ANL minus
OZZ when interconnecting to the BA operator services network.

20.0   COORDINATION WITH TARIFF TERMS

       20.1    The Parties acknowledge that some of the services, facilities, 
and arrangements described herein are or will be available under and subject to 
the terms of the federal or state tariffs of the other Party applicable to such
services, facilities, and arrangements. To the extent a Tariff of the providing
Party applies to any service, facility, and arrangement described herein, the
Parties agree as follows:

               20.1.1    Those rates and charges set forth in Exhibit A for the
services, facilities, and arrangements described herein that are designated with
an asterisk shall remain fixed for the initial term of the Agreement,
notwithstanding that such rates may be different from those contained in an
effective, pending, or future Tariff of the providing Party (including any
changes to such Tariff subsequent to the Effective Date). Those rates and
charges for services, facilities, and arrangements that are not designated with
an asterisk, and reference or are identical to a rate contained in an existing
Tariff of the providing Party, shall conform with those contained in the then-
prevailing Tariff and vary in accordance with any changes that may be made to
the Tariff rates and charges subsequent to the Effective Date. Even the
asterisked fixed rates and charges shall be changed to reflect any changes in
the Tariff rates and charges they reference, however, if the Parties agree to
adopt the changed Tariff rates and charges.

       20.2    Except with respect to the rates and charges described in 
subsection 20.1 above, all other terms contained in an applicable Tariff of the 
providing Party shall apply in connection with its provision of the particular
service, facility, and arrangement hereunder.

21.0   INSURANCE

       21.1    MFS shall maintain, during the term of this Agreement, all 
insurance and/or bonds required by law and necessary to satisfy its obligations 
under this Agreement, including, without limitation, its obligations set forth
in Section 25 hereof. At a minimum and without limiting the foregoing covenant,
MFS shall maintain the following insurance:

               (a)  Commercial General Liability Insurance, on an occurrence
       basis, including but not limited to, premises-operations, broad form
       property damage, products/completed operations, contractual liability,
       independent contractors, and personal injury, with limits of at least
       $1,000,000 combined single limit for each occurrence.

               (b)  Automobile Liability, Comprehensive Form, with limits of at 
       least $500,000 combined single limit for each occurrence.

                                      47


<PAGE>
 
            (c)  Excess Liability, in the umbrella form, with limits of at least
      $15,000,000 combined single limit for each occurrence.

            (d)  Worker's Compensation Insurance as required by law and
      Employer's Liability Insurance with limits of not less than $1,000,000 per
      occurrence.


      21.2   MFS shall name BA as an additional insured on the foregoing
insurance. MFS agrees that MFS's insurer(s) and anyone claiming by, through,
under or on behalf of MFS, shall have no claim, right of action, or right of
subrogation, against BA. BA's affiliated companies, or the directors, officers
or employees of BA or BA's affiliated companies, based on any loss or liability
insurable under the foregoing insurance.

      21.3   MFS shall, within two (2) weeks of the date hereof and on a 
quarterly basis thereafter, furnish certificates or other adequate proof of the 
foregoing insurance. The certificates or other proof of the foregoing insurance 
shall be sent to: Bell Atlantic, Insurance Administration Group, 1320 N. Court 
House Road, 4th Floor, Arlington, Virginia, 22201. In addition, MFS shall 
require its agents, representatives, or contractors, if any, that may enter upon
the premises of BA or BA's affiliated companies to maintain similar and 
appropriate insurance and, if requested, to furnish BA certificates or other 
adequate proof of such insurance. Certificates furnished by MFS or MFS's agents,
representatives, or contractors shall contain a clause stating: "Bell Atlantic -
Virginia, Inc. shall be notified in writing at least thirty (30) days prior to 
cancellation of, or any material change in, the insurance."

22.0  TERM AND TERMINATION.

      22.1   This Agreement shall be effective as of the date first above
written and continue in effect until July 1, 1999, and thereafter the Agreement
shall continue in force and effect unless and until terminated as provided
herein. Upon the expiration of the initial term, either Party may terminate this
Agreement by providing written notice of termination to the other Party, such
written notice to be provided at least ninety (90) days in advance of the date
of termination. In the event of such termination, those service arrangements
made available under this Agreement and existing at the time of termination
shall continue without interruption under (a) a new agreement executed by the
Parties, (b) standard Interconnection terms and conditions approved and made
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLEC, or (d) if none of the above is available, under the terms of
this Agreement on a month-to-month basis until such time as (a), (b), or (c)
becomes available.

     22.2    For service arrangements made available under this Agreement and 
existing at the time of termination, if the standard Interconnection terms and 
conditions or Tariff terms and conditions result in the non-terminating Party 
physically rearranging facilities or incurring programming expense, the 
non-terminating Party shall be entitled to recover such rearrangement or 
programming costs, from the terminating Party. By mutual agreement, the Parties
may jointly petition the appropriate regulatory bodies for permission to have
this Agreement supersede any future standardized agreements or rules as such
regulators might adopt or approve.

                                      48
<PAGE>
 
       22.3  If either Party defaults in the payment of any amount due
hereunder, or if either Party violates any other provision of this Agreement,
and such default or violation shall continue for sixty (60) days after written
notice thereof, the other Party may terminate this Agreement and services
hereunder by written notice; provided the other Party has provided the
defaulting Party and the appropriate federal and/or state regulatory bodies with
written notice at least twenty five (25) days' prior to terminating service.
Notice shall be posted by certified mail, return receipt requested. If the
defaulting Party cures the default or violation within the twenty five (25) day
period, the other Party will not terminate service or this Agreement but shall
be entitled to recover all costs, if any, incurred by it in connection with the
default or violation, including, without limitation, costs incurred to prepare
for the termination of service.

23.0   DISCLAIMER OF REPRESENTATIONS AND WARRANTIES.
     
       EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NEITHER PARTY MAKES
ANY WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES, FUNCTIONS AND
PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND THE PARTIES
DISCLAIM THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A
PARTICULAR PURPOSE.

24.0   CANCELLATION CHARGES.
     
       Except as provided in this Agreement or as otherwise provided in any
applicable Tariff, no cancellation charges shall apply.

25.0   INDEMNIFICATION.

       25.1  Each Party agrees to release, indemnify, defend and hold harmless
the other Party from and against all losses, claims, demands, expenses, suits or
other actions, or any liability whatsoever, including, but not limited to, costs
and attorneys' fees (collectively, a "Loss"), (a) whether suffered, made,
instituted, or asserted by any other party or person, (i) relating to personal
injury to or death of any person, or for loss, damage to, or destruction of real
and/or personal property, whether or not owned by others, incurred during the
term of this Agreement and to the extent proximately caused by the acts or
omissions of the indemnifying Party, regardless of the form of action, or (ii)
arising out of BA's listing of the directory listing information provided by MFS
pursuant to subsection 19.1. or (b) suffered, made, instituted, or asserted by
its own customer(s) against the other Party arising out of the other Party's
provision of services to the indemnifying Party under this Agreement.
Notwithstanding the foregoing indemnification, nothing in this such Section 25,
shall affect or limit any claims, remedies, or other actions the indemnifying
Party may have against the indemnified Party under this Agreement, any other
contract, or any applicable Tariff(s), regulations or laws for the indemnified
Party's provision of said services.

                                      49

<PAGE>
 
       25.2    The indemnification provided herein shall be conditioned upon:

               (a)  The indemnified Party shall promptly notify the indemnifying
       Party of any action taken against the indemnified Party relating to the
       indemnification.

               (b)  The indemnifying Party shall have sole authority to defend 
       any such action, including the selection of legal counsel, and the
       indemnified Party may engage separate legal counsel only at its sole cost
       and expense.

               (c)  In no event shall the indemnifying Party settle or consent 
       to any judgment pertaining to any such action without the prior written
       consent of the indemnified Party, which consent shall not be unreasonably
       withheld.

               (d)  The indemnified Party shall, in all cases, assert any and 
       all provisions in its Tariffs that limit liability to third parties as a
       bar to any recovery by the third party claimant in excess of such
       limitation of liability.

               (e)  The indemnified Party shall offer the indemnifying Party all
       reasonable cooperation and assistance in the defense of any such action.

       25.3    In addition to its indemnity obligations under subsection 25.1, 
each Party shall provide, in its tariffs and contracts with its Customers that 
relate to any Telecommunications Service or Network Element provided or 
contemplated under this Agreement, that in no case shall such Party or any of 
its agents, contractors or others retained by such parties be liable to any 
Customer or third party for (i) any Loss relating to or arising out of this 
Agreement, whether in contract or tort, that exceeds the amount such Party would
have charged the applicable Customer for the service(s) or function(s) that gave
rise to such Loss, and (ii) any Consequential Damages (as defined in subsection 
26.2 below).

26.0   LIMITATION OF LIABILITY.

       26.1    Except as may be provided pursuant to Section 27 below, the 
liability of either Party to the other Party for damages arising out of failure 
to comply with a direction to install, restore or terminate facilities; or out 
of failures, mistakes, omissions, interruptions, delays, errors, or defects 
occurring in the course of furnishing any services, arrangements, or facilities 
hereunder shall be determined in accordance with the terms of the applicable 
tariff(s) of the providing Party. In the event no tariff(s) apply, the providing
Party's liability shall not exceed an amount equal to the pro rata monthly 
charge for the period in which such failures, mistakes, omissions, 
interruptions, delays, errors or defects occur. Recovery of said amount shall be
the injured Party's sole and exclusive remedy against the providing Party for 
such failures, mistakes, omissions, interruptions, delays, errors or defects.

       26.2    Neither Party shall be liable to the other in connection with the
provision or use of services offered under this Agreement for indirect, 
incidental, consequential, reliance or special

                                      50
<PAGE>
 
damages, including (without limitation) damages for lost profits (collectively, 
"Consequential Damages"), regardless of the form of action, whether in contract,
warranty, strict liability, or tort, including, without limitation, negligence 
of any kind, even if the other Party has been advised of the possibility of such
damages; provided, that the foregoing shall not limit a Party's obligation under
Section 25.

       26.3    The Parties agree that neither Party shall be liable to the 
customers of the other Party in connection with its provision of services to the
other Party under this Agreement. Nothing in this Agreement shall be deemed to 
create a third party beneficiary relationship between the Party providing the 
service and the customers of the Party purchasing the service. In the event of a
dispute involving both Parties with a customer of one Party both Parties shall 
assert the applicability of any limitations on liability to customers that may 
be contained in either Party's applicable Tariff(s).

27.0   PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES.

       27.1    CERTAIN DEFINITIONS.  When used in this Section 27, the following
terms shall have the meanings indicated.

               27.1.1  "Specified Performance Breach" means the failure by BA 
to meet the Performance Criteria for any one of the three Specified Activities 
for a period of three (3) consecutive calendar months.

               27.1.2  "Specified Activity" means any of the following 
activities:

               (a)     the installation by BA of Unbundled Local Loop Elements 
       for MFS ("ULL Installation"):

               (b)     BA's provision of INP to MFS or

               (c)     repair of out of service problems for MFS ("Out of 
       Service Repairs").

               27.1.3  "Performance Criteria" means, with respect to any 
calendar month during the term of this Agreement, the performance by BA during 
such month of each Specified Activity (except Out-of-Service Repairs) shown in 
Schedule 27.0, within the time interval shown, in at least eighty percent (80%) 
of the covered instances.  BA shall perform the Out-of-Service Repairs within 
the specified time interval in at least seventy percent (70%) of the covered 
instances. Within one week of each anniversary of the Effective Date, the 
Parties shall jointly review BA's actual network-wide monthly performance
percentages for Out-of-Service Repairs for the preceding year and agree upon any
improvements in the seventy percent (70%) standard based on the actual
percentages for any three consecutive month period and/or the full preceding
year, up to and including any eighty percent (80%) standard, as the Out-of-
Service Repairs percentage standard applicable to the following year.

                                      51
<PAGE>
 
       27.2    PERFORMANCE STANDARDS.  BA shall exercise best efforts to meet 
the Performance Criteria for the three Specified Activities. In the event BA 
fails to meet the Performance Criteria at any time during the term of this 
Agreement, MFS shall be entitled to pursue all remedies set forth in the 
applicable BA Tariffs, except as may be agreed to by the Parties. In addition, 
if BA commits a Specified Performance Breach during the term of this Agreement, 
the Parties agree to meet immediately to determine whether any liquidated 
damages provisions are appropriate as an amendment hereof in light of such 
Breach and, if so, the terms therein; provided, however, that if BA commits a 
Specified Performance Breach during initial nine (9) months of this Agreement, 
the Parties agree to meet at the end of the nine-month period. If the Parties 
are unable to agree as to the appropriateness of the liquidated damages 
provisions and or the terms therein within ninety (90) days after the date of 
the first meeting pursuant to this subsection, or if no such meeting has
occurred within ninety (90) days of the end of the nine-month period for reasons
other than the mutual agreement of the Parties, the Parties agree to submit to
arbitration such disagreement and request that the arbitrators base their
decision on comparable ILEC-CLEC interconnection agreements. Unless otherwise
agreed to by the Parties, the arbitration shall be conducted by a panel of three
(3) arbitrators, one to be appointed by each Party pursuant to CPR's Non-
Administered Arbitration Rules and subject to the United States Arbitration Act
(9 U.S.C (S)(S) 1-16), to be conducted in Arlington, Virginia. The Parties agree
that the liquidated damages provisions, if any, finally determined by the
arbitral process shall be adopted as an amendment to this Agreement.

       27.3    LIMITATIONS.  In no event shall BA be deemed to have failed to 
meet any of the Performance Criteria if:

               27.3.1  BA's failure to meet or exceed any of the Performance 
Criteria is caused, directly or indirectly, by a Delaying Event. A "Delaying 
Event" means (a) a failure by MFS to perform any of its obligations set forth in
this Agreement (including, without limitation, the Implementation Schedule and 
the Joint Grooming Plan), (b) any delay, act or failure to act by a Customer, 
agent, representative, or subcontractor of MFS or (c) any Force Majeure Event. 
If a Delaying Event prevents or delays BA from performing a Specified Activity, 
then such Specified Activity shall be excluded from the calculation of BA's 
compliance with the Performance Criteria, provided BA performs the Specified 
Activity in the course of its normal service cycle once the Delaying Event no 
longer exists; or

               27.3.2  the Parties agree to a time interval with respect to a 
particular order that exceeds the interval set forth in Schedule 27. In such 
event, the time interval for BA's performance of the Specified Activit(ies) set 
forth in the order shall be extended to such later date agreed to by the 
Parties.

       27.4    SERVICE QUALITY STANDARDS.  MFS agrees to specific performance 
standards associated with quality of service requests as specified in Schedule 
27.1. Should MFS fail to meet these service quality standards, during a period 
in which BA has failed to meet the Performance Criteria. BA's failure during 
such time period shall be excused and not apply toward the calculation of a 
Specified Performance Breach.

                                      52
<PAGE>
 
       27.5    RECORDS.  Each Party shall maintain complete and accurate records
in the manner and format agreed to by the Parties, on a monthly basis, of BA's 
performance under this Agreement of each Specified Activity and its compliance 
with the Performance Criteria during the initial nine-month period. Each Party 
shall provide to the other Party such records in a self-reporting format on a 
monthly basis. The Parties agree that such records shall be deemed "Proprietary 
Information" for purposes of subsection 29.4.

28.0   COMPLIANCE WITH LAWS; REGULATORY APPROVAL.

       28.1    Each Party represents and warrants that it is now and will remain
in compliance with all laws, regulations, and orders applicable to the 
performance of its obligations hereunder (collectively, "Applicable Lawss"). 
Each Party shall promptly notify the other Party in writing of any governmental
action that suspends, cancels, withdraws, limits, or otherwise materially
affects its ability to perform its obligations hereunder.

       28.2    The Parties understand and agree that this Agreement will be 
filed with the Commission and may thereafter be filed with the FCC. The Parties 
covenant and agree that this Agreement is satisfactory to them as an agreement 
under Section 251 of the Act. Each Party covenants and agrees to fully support 
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek 
regulatory relief and otherwise seek redress from each other regarding 
performance and implementation of this Agreement.

       28.3    The Parties recognize that the FCC is currently, promulgating 
regulations implementing the Act, including, without limitation, Sections 251, 
252, and 271 thereof (the "FCC Regulations"), that may affect the terms 
contained in this Agreement. In the event that any one or more of the provisions
contained herein is inconsistent with any such FCC Regulations, the Parties 
agree to make only the minimum revisions necessary to eliminate the 
inconsistency. Such minimum changes to conform this Agreement to the FCC 
Regulations shall not be considered material, and shall not require further 
Commission approval (beyond any Commission approval required under Section 
252(e) of the Act).

       28.4    In the event any Applicable Laws other than the FCC Regulations 
requires modification of any material term(s) contained in this Agreement, 
either Party may require a renegotiation of the term(s) that require direct 
modification as well as of any term(s) that are reasonably affected thereby. If 
neither Party requests a renegotiation or if an Applicable Laws requires 
modification of any non-material term(s), then the Parties agree to make only 
the minimum modifications necessary, and the remaining provisions of this 
Agreement shall remain in full force and effect. For purposes of this subsection
28.4 and without limitation of any other modifications required by Applicable 
Lawss, the Parties agree that any modification required by Applicable Lawss (i) 
to the two-tier Reciprocal Call Termination compensation structure for the 
transport and termination of Local Tariff described in Exhibit A, or (ii) that 
affects either Party's receipt of reciprocal compensation for the transport and 
termination of Local Tariff, shall be deemed to be a modification of a material 
term that requires immediate good faith renegotiation between the Parties.

                                      53
<PAGE>
 
Until such renegotiation results in a new agreement or an amendment to this 
Agreement between the Parties, the Parties agree that (y) in the case of (i) 
above, they will pay each other appropriate transport charges in addition to the
usual call termination charge for Local Traffic that it delivers to the other 
Party's Local Serving Wire Center, provided each Party continues to offer the 
option of delivering Local Traffic to another IP in the LATA at the usual call 
termination charge only, and (z) in the case of (ii) above, the Party whose 
receipt of reciprocal compensation is affected shall not be obligated to pay the
other Party reciprocal compensation for the other Party's transport and 
termination of the same kind of Local Traffic delivered by the affected Party in
excess of what the affected Party is permitted to receive and retain.

29.0   MISCELLANEOUS.

       29.1    AUTHORIZATION.

               29.1.1  BA is a corporation duly organized, validly existing and 
in good standing under the laws of the Commonwealth of Virginia and has full 
power and authority to execute and deliver this Agreement and to perform the 
obligations hereunder on behalf of BA.

               29.1.2  MFS is a corporation duly organized, validly existing and
in good standing under the laws of the State of Delaware and has full power and 
authority to execute and deliver this Agreement and to perform its obligations 
hereunder.

       29.2    INDEPENDENT CONTRACTOR.  Each Party shall perform services 
hereunder as an independent contractor and nothing herein shall be construed as 
creating any other relationship between the Parties. Each Party and each Party's
contractor shall be solely responsible for the withholding or payment of all 
applicable federal, state and local income taxes, social security taxes and 
other payroll taxes with respect to their employees, as well as any taxes, 
contributions or other obligations imposed by applicable state unemployment or 
workers' compensation acts. Each Party has sole authority and responsibility to 
hire, fire and otherwise control its employees.

       29.3    FORCE MAJEURE.  Neither Party shall be responsible for delays or 
failures in performance resulting from acts or occurrences beyond the reasonable
control of such Party, regardless of whether such delays or failures in 
performance were foreseen or foreseeable as of the date of this Agreement, 
including, without limitation: adverse weather conditions, fire, explosion, 
power failure, acts of God, war, revolution, civil commotion, or acts of public 
enemies; any law, order, regulation, ordinance or requirement of any government 
or legal body; or labor unrest, including, without limitation, strikes, 
slowdowns, picketing or boycotts; or delays caused by the other Party or by 
other service or equipment vendors; or any other circumstances beyond the 
Party's reasonable control. In such event, the affected Party shall, upon giving
prompt notice to the other Party, be excused from such performance on a 
day-to-day basis to the extent of such interferences (and the other Party shall 
likewise be excused from performance of its obligations on a day-to-day basis 
to the extent such Party's obligations relate to the performance so interfered 
with). The affected Party shall use its best efforts to avoid or remove the 
cause(s) of non-

                                      54
<PAGE>
 
performance and both Parties shall proceed to perform with dispatch once the 
cause(s) are removed or cease.

       29.4    CONFIDENTIALITY.
     
               29.4.1  All information, including but not limited to 
specification, microfilm, photocopies, magnetic disks, magnetic tapes, drawings,
sketches, models, samples, tools, technical information, data, employee records,
maps, financial reports, and market data, (i) furnished by one Party to the 
other Party dealing with customer specific, facility specific, or usage 
specific information, other than customer information communicated for the 
purpose of publication or directory database inclusion, or (ii) in written, 
graphic, electromagnetic, or other tangible form and marked at the time of 
delivery as "Confidential" or "Proprietary," or (iii) communicated orally and 
declared to the receiving Party at the time of delivery, or by written notice 
given to the receiving Party within ten (10) days after delivery, to be 
"Confidential" or "Proprietary" (collectively referred to as "Proprietary 
Information"), shall remain the property of the disclosing Party.

               29.4.2  Each Party shall keep all of the other Party's 
Proprietary Information confidential and shall use the other Party's Proprietary
Information only for performing the covenants contained in this Agreement. 
Neither Party shall use the other Party's Proprietary Information for any other 
purpose except upon such terms and conditions as may be agreed upon between the 
Parties in writing.

               29.4.3  Unless otherwise agreed, the obligations of 
confidentiality and non-use set forth in this Agreement do not apply to such 
Proprietary Information that:

               (a)     was, at the time of receipt, already known to the 
       receiving Party free of any obligation to keep it confidential as
       evidenced by written records prepared prior to delivery by the disclosing
       Party; or

               (b)     is or becomes publicly known through no wrongful act of 
       the receiving Party; or

               (c)     is rightfully received from a third person having no 
       direct or indirect secrecy or confidentiality obligation to the
       disclosing Party with respect to such information; or

               (d)     is independently developed by an employee, agent, or 
       contractor of the receiving Party that is not involved in any manner with
       the provision of services pursuant to this Agreement and does not have
       any direct or indirect access to the Proprietary Information; or

               (e)     is approved for release by written authorization of the 
       disclosing Party; or

               (f)     is required to be made public by the receiving Party 
       pursuant to applicable law or regulation, provided that the receiving
       Party shall give sufficient notice of the requirement to the disclosing
       Party to enable the disclosing Party to seek protective orders.

                                      55


<PAGE>
 
               29.4.4  Upon request by the disclosing Party, the receiving Party
shall return all tangible copies of Proprietary Information, whether written, 
graphic or otherwise, except that the receiving Party may retain one copy for 
archival purposes only.

               29.4.5  Notwithstanding any other provision of this Agreement, 
the provisions of this subsection 29.4 shall apply to all Proprietary 
Information furnished by either Party to the other in furtherance of the purpose
of this Agreement, even if furnished before the Effective Date.

       29.5    CHOICE OF LAW.  The construction, interpretation and performance 
of this Agreement shall be governed by and construed in accordance with the laws
of the state in which this Agreement is to be performed, except for its 
conflicts of laws provisions. In addition, insofar as and to the extent federal 
law may apply, federal law will control.

       29.6    TAXES
          
               29.6.1. In General.  With respect to any purchase hereunder of 
                       ----------
services, facilities or arrangements, if any federal, state or local tax, fee, 
surcharge or other tax-like charge (a "Tax") is required or permitted by 
Applicable Laws (as defined in subsection 28.1) to be collected from the 
purchasing Party by the providing Party, then (i) the providing Party shall 
properly bill the purchasing Party for such Tax, (ii) the purchasing Party shall
timely remit such Tax to the providing Party and (iii) the providing Party shall
timely remit such collected Tax to the applicable taxing authority.

               29.6.2. Taxes Imposed on the Providing Party.  With respect to 
                       ------------------------------------
any purchase hereunder of services, facilities or arrangements, if any federal, 
state or local Tax is imposed by Applicable Laws on the receipts of the 
providing Party, which Law permits the providing Party to exclude certain 
receipts received from sales for resale to a public utility, distributor, 
telephone company, local exchange carrier, telecommunications company or other 
communications company ("Telecommunications Company"), such exclusion being 
based solely on the fact that the purchasing Party is also subject to a tax 
based upon receipts ("Receipts Tax"), then the purchasing Party (i) shall 
provide the providing Party with notice in writing in accordance with subsection
29.6.6 of this Agreement of its intent to pay the Receipts Tax and (ii) shall 
timely pay the Receipts Tax to the applicable tax authority.

               29.6.3. Taxes Imposed on Customers.  With respect to any purchase
                       --------------------------
hereunder of services, facilities or arrangements that are resold to a third 
party, if any federal, state or local Tax is imposed by Applicable Laws on the 
subscriber, end-user, Customer or ultimate consumer ("Subscriber") in connection
with any such purchase, which a Telecommunications Company is required to impose
and/or collect from a Subscriber, then the purchasing Party (i) shall be 
required to impose and/or collect such Tax from the Subscriber and (ii) shall 
timely remit such Tax to the applicable taxing authority.

               29.6.4. Liability for Uncollected Tax, Interest and Penalty.  If 
                       ---------------------------------------------------
the providing Party has not received an exemption certificate and fails to 
collect any Tax as required by subsection,

                                      56
<PAGE>
 
29.6.1, then, as between the providing Party and the purchasing Party, (i) the 
purchasing Party shall remain liable for such uncollected Tax and (ii) the 
providing Party shall be liable for any interest assessed thereon and any 
penalty assessed with respect to such uncollected Tax by such authority. If the 
providing Party properly bills the purchasing Party for any Tax but the 
purchasing Party fails to remit such Tax to the providing Party as required by 
subsection 29.6.1, then, as between the providing Party and the purchasing 
Party, the purchasing Party shall be liable for such uncollected Tax and any 
interest assessed thereon, as well as any penalty assessed with respect to such 
uncollected Tax by the applicable taxing authority. If the providing Party does 
not collect any Tax as required by subsection 29.6.1 because the purchasing 
Party has provided such providing Party with an exemption certificate that is 
later found to be inadequate by a taxing authority, then, as between the 
providing Party and the purchasing Party, the purchasing Party shall be liable 
for such uncollected Tax and any interest assessed thereon, as well as any 
penalty assessed with respect to such uncollected Tax by the applicable taxing 
authority. If the purchasing Party fails to pay the Receipts Tax as required by 
subsection 29.6.2, then, as between the providing Party and the purchasing 
Party, (x) the providing Party shall be liable for any Tax imposed on its 
receipts and (y) the purchasing Party shall be liable for any interest assessed 
thereon and any penalty assessed upon the providing Party with respect to such 
Tax by such authority. If the purchasing Party fails to impose and or collect 
any Tax from Subscribers as required by subsection 29.6.3, then, as between the 
providing Party and the purchasing Party, the purchasing Party shall remain 
liable for such uncollected Tax and any interest assessed thereon, as well as 
any penalty assessed with respect to such uncollected Tax by the applicable 
taxing authority. With respect to any Tax that the purchasing Party has agreed 
to pay, or is required to impose on and/or collect from Subscribers, the 
purchasing Party agrees to indemnify and hold the providing Party harmless on an
after-tax basis for any costs incurred by the providing Party as a result of 
actions taken by the applicable taxing authority to recover the Tax from the 
providing Party due to the failure of the purchasing Party to timely pay, or 
collect and timely remit, such Tax to such authority. In the event either Party 
is audited by a taxing authority, the other Party agrees to cooperate fully with
the Party being audited in order to respond to any audit inquiries in a proper 
and timely manner so that the audit and/or any resulting controversy may be 
resolved expeditiously.

               29.6.5  Tax Exemptions and Exemption Certificates.  If Applicable
                       -----------------------------------------
Laws clearly exempts a purchase hereunder from a Tax, and if such Law also 
provides an exemption procedure, such as an exemption-certificate requirement, 
then, if the purchasing Party complies with such procedure, the providing Party 
shall not collect such Tax during the effective period of such exemption. Such 
exemption shall be effective upon receipt of the exemption certificate or 
affidavit in accordance with the terms set forth in subsection 29.6.6. If 
Applicable Laws clearly exempts a purchase hereunder from a Tax, but does not 
also provide an exemption procedure, then the providing Party shall not collect 
such Tax if the purchasing Party (i) furnishes the providing Party with a letter
signed by an officer requesting such an exemption and citing the provision in 
the Law which clearly allows such exemption and (ii) supplies the providing 
Party with an indemnification agreement, reasonably acceptable to the providing 
Party (e.g., an agreement commonly used in the industry), which holds the 
       - -
providing Party harmless on an after-tax basis with respect to its forbearing to
collect such Tax.

                                      57
<PAGE>
 
          29.6.6.   Notices for Purposes of this Subsection 29.6.  All notices, 
                    --------------------------------------------
affidavits, exemption-certificates or other communications required or permitted
to be given by either Party to the other, for purposes of this subsection 29.6, 
shall be made in writing and shall be delivered in person or sent by certified 
mail, return receipt requested, or registered mail, or a courier service 
providing proof of service, and sent to the addresses set forth in subsection 
29.10 as well as to the following:

     To Bell Atlantic:        Tax Administration
                              Bell Atlantic Network Services, Inc.
                              1717 Arch Street
                              30th Floor
                              Philadelphia, PA 19103

     To MFS:                  Corporate Tax Department
                              MFS Communications Company, Inc.
                              11808 Miracle Hills Drive
                              Omaha, Nebraska 68154

Either Party may from time to time designate another address or other addressees
by giving notice is accordance with the terms of this subsection 29.6. Any
notice or other communication shall be deemed to be given when received.

     29.7 ASSIGNMENT.  Neither Party shall assign this Agreement nor any of its 
rights or obligations hereunder without the prior written consent of the other 
Party, which consent shall not be unreasonably withheld. Any assignment or 
delegation in violation of this subsection 29.7 shall be void and ineffective 
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS.

          29.8.1  Except may otherwise be provided in this Agreement, each Party
shall submit on a monthly basis an itemized statement of charges incurred by the
other Party during the preceding month(s) for services rendered hereunder. 
Payment of billed amounts under this Agreement, whether billed on a monthly 
basis or as otherwise provided herein, shall be due, in immediately available 
U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2  Although it is the intent of both Parties to submit timely and
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or 
a waiver of the right to payment of the incurred charges, by the billing Party 
under this Agreement, and the billed Party shall not be entitled to dispute the 
billing Party statement(s) based on such Party's failure to submit them in a 
timely fashion.

          29.8.3  If any portion of an amount due to a Party (the "Billing 
Party") under this Agreement is subject to a bona fide dispute between the 
Parties, the Party billed (the "Non-Paying Party") shall within sixty (60) days 
of its receipt of the invoice containing such

                                      58

<PAGE>
 
disputed amount give notice to the Billing Party of the amounts it disputes 
("Disputed Amounts") and include in such notice the specific details and reasons
for disputing each item. The Non-Paying Party shall pay when due (i) all 
undisputed amounts to the Billing Party and (ii) all Disputed Amounts into an 
interest bearing escrow account with a third party escrow agent mutually agreed 
upon by the Parties.

            29.8.4    If the Parties are unable to resolve the issues related to
the Disputed Amounts in the normal course of business within ninety (90) days
after delivery to the Billing Party of notice of the Disputed Amounts, each of
the Parties shall appoint a designated representative that has authority to
settle the dispute and that is at a higher level of management than the persons
with direct responsibility for administration of this Agreement. The designated
representatives shall meet as often as they reasonably deem necessary in order
to discuss the dispute and negotiate in good faith in an effort to resolve such
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

            29.8.5    If the Parties are unable to resolve issues related to the
Disputed Amounts within forty-five (45) days after the Parties' appointment of
designated representatives pursuant to subsection 29.8.4, then either Party may
file a complaint with the Commission to resolve such issues or proceed with any
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus
applicable late fees, to be paid to either Party.

            29.8.6    The Parties agree that all negotiations pursuant to this
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state
rules of evidence.

            29.8.7    Any undisputed amounts not paid when due shall accrue
interest from the date such amounts were due at the lesser of (i) one and one-
half percent (1-1/2%) per month or (ii) the highest rate of interest that may be
charged under applicable law.

     29.9   DISPUTE RESOLUTION. Any dispute between the Parties regarding the
interpretation or enforcement of this Agreement or any of its terms shall be 
addressed by good faith negotiation between the Parties, in the first instance. 
Should such negotiations fail to resolve the dispute in a reasonable time, 
either Party may initiate an appropriate action in any regulatory or judicial 
forum of competent jurisdiction.

     29.10  NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing and shall be (a) delivered personally, (b) 
delivered by express delivery service, (c) mailed, certified mail or first class
U.S. mail postage prepaid, return receipt requested, or (d) delivered by 
telecopy to the following addresses of the Parties.

               To MFS:

                                      59
<PAGE>
 
               MFS Intelenet of Virginia, Inc.
               33 Whitehall St.
               15/th/ floor
               New York, NY 10004
               Attn: Director, Regulatory Affairs - Eastern Region
               Facsimile: 212/843-3060


               To Bell Atlantic:

               Director - Interconnection Services
               Bell Atlantic Network Services, Inc.
               1320  N. Courthouse Road
               9/th/ Floor
               Arlington, VA 22201
               Facsimile: 703/974-2183

               with a copy to:

               Vice President and General Counsel
               Bell Atlantic - Virginia, Inc.
               600 East Main Street
               24/th/ Floor
               Richmond, VA 23261
               Facsimile: (804) 772-2143

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual
receipt, (ii) the next business day when notice is sent via express mail or
personal delivery, (iii) three (3) days after mailing in the case of first 
class or certified U.S. mail, or (iv) on the date set forth on the confirmation 
in the case of telecopy.

          29.11  SECTION 252(I) OBLIGATIONS.

                 29.11.1 If, at any time during the term of this Agreement,
either Party enters into an agreement to provide an integrated package of
services or arrangements substantially similar to that described herein to
another CLEC (in the case of BA), or another incumbent LEC (in the case of MFS),
operating within the same state to which this Agreement applies, on terms
significantly different than those available under this Agreement (the "Other
Agreement"), then the other Party may opt to adopt, on a prospective basis only,
the rates, terms, and conditions contained in the Other Agreement (i) in its
entirety, or (ii) that relate directly to any of the following individual
services. Network Elements, or arrangements, for its own reciprocal arrangements
with the first Party, including, without limitation, any term or volume
commitments or network architecture configurations:

                                      60




<PAGE>
 
               (a)  Unbundled Loop Elements - Section 251(c)(3) of the Act 
(Section 11 of this Agreement); or

               (b)  Collocation - Section 251(c)(6) of the Act (Section 13 of 
this Agreement); or

               (c)  Number Portability - Section 251(b)(2) of the Act (Section 
14 of this Agreement); or

               (d)  Access to Rights of Way - Section 251(b)(4) of the Act 
(Section 16 of this Agreement).

               (e)  transiting arrangements.

               29.11.2   To the extent the exercise of the foregoing options 
requires a rearrangement of facilities by the providing Party, the opting Party 
shall be liable for the non-recurring charges associated therewith.

               29.11.3   The Party electing to exercise such option shall do so 
by delivering written notice to the first Party. Upon receipt of said notice by 
the first Party, the Parties shall amend this Agreement to provide the same 
rates, terms and conditions to the notifying Party for the remaining term of 
this Agreement; provided, however, that the Party exercising its option under 
this subsection 29.11 must continue to provide the same services or arrangements
to the first Party as required by this Agreement, subject either to the rates, 
terms, and conditions applicable to the first Party in its agreement with the 
third party or to the rates, terms, and conditions of this Agreement, whichever 
is more favorable to the first Party in its sole determination.

               29.11.4   BA represents and warrants that, as of the date of this
Agreement, it has not entered into any comparable Interconnection agreement with
any other CLEC in BA's service territory that is significantly more favorable 
than the terms contained herein. BA makes no warranty or representation with 
respect to its Interconnection arrangements with its affiliates of ITCs.

     29.12     JOINT WORK PRODUCT. This Agreement is the joint work product of
the Parties and has been negotiated by the Parties and their respective counsel
and shall be fairly interpreted in accordance with its terms and, in the event
of any ambiguities, no inferences shall be drawn against either Party.


     29.13     NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. This 
Agreement is for the sole benefit of the Parties and their permitted assigns, 
and nothing herein express or implied shall create or be construed to create any
third-party beneficiary rights hereunder. Except for provisions herein expressly
authorizing a Party to act for another, nothing in this Agreement shall 
constitute a Party as a legal representative or agent of the other Party, nor 
shall a Party have the right or authority to assume, create or incur any 
liability or any obligation of any kind, express or implied, against or in the 
name or on behalf of the other Party unless otherwise expressly

                                      61












    
<PAGE>
 
permitted by such other Party. Except as otherwise expressly provided in this 
Agreement, no Party undertakes to perform any obligation of the other Party, 
whether regulatory or contractual, or to assume any responsibility for the 
management of the other Party's business.

     29.14     NO LICENSE.

               29.14.1 Nothing in this Agreement shall be construed as the grant
of a license, either express or implied, with respect to any patent, copyright, 
trademark, trade name, trade secret or any other proprietary or intellectual 
property now or hereafter owned, controlled or licensable by either Party. 
Neither Party may use any patent, copyrightable materials, trademark, trade 
name, trade secret or other intellectual property right of the other Party 
except in accordance with the terms of a separate license agreement between the 
parties granting such rights.

               29.14.2 Neither Party shall have any obligation to defend, 
indemnify or hold harmless, or acquire any license or rights for the benefit  
of, or owe any other obligation or have any liability to, the other Party or its
customers based on or arising from any claim, demand, or proceeding by any third
party alleging or asserting that the use of any circuit, apparatus, or system,
or the use of any software, or the performance of any service or method, or the
provision of any facilities by either Party under this Agreement, alone or in
combination with that of the other Party, constitutes direct, vicarious or
contributory infringement or inducement to infringe, misuse or misappropriation
of any patent, copyright, trademark, trade secret, or any other proprietary or
in intellectual property right of any Party or third party. Each Party, however,
shall offer to the other reasonable cooperation and assistance in the defence of
any such claim.

               29.14.3   NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT,
THE PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST,
ANY WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.
                    
     29.15     TECHNOLOGY UPGRADES. Nothing in this Agreement shall limit BA's
ability to upgrade its network through the incorporation of new equipment, new
software or otherwise. BA shall provide MFS written notice at least ninety (90)
days prior to the incorporation of any such upgrades in BA's network that will
materially affect MFS's service. MFS shall be solely responsible for the cost
and effort of accommodating such changes in its own network.

     29.16     SURVIVAL. The Parties' obligations under this Agreement which by
their nature are intended to continue beyond the termination or expiration of
this Agreement shall survive the termination or expiration of this Agreement.


     29.17     ENTIRE AGREEMENT. The terms contained in this Agreement and any 
Schedules, Exhibits, tariffs and other document or instruments referred to 
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with

                                      62








    




<PAGE>
 
respect to the subject matter hereof, superseding all prior understandings, 
proposals and other communications, oral or written. Neither Party shall be 
bound by any preprinted terms additional to or different from those in this 
Agreement that may appear subsequently in the other Party's form documents, 
purchase orders, quotations, acknowledgments, invoices or other communications.

     29.18     COUNTERPARTS.  This Agreement may be executed in two or more 
counterparts, each of which shall be deemed an original and all of which 
together shall constitute one and the same instrument.

     29.19     MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER. No modification, 
amendment, supplement to, or waiver of the Agreement or any of its provisions 
shall be effective and binding upon the Parties unless it is made in writing and
duly signed by the Parties. A failure or delay of either Party to enforce any of
the provisions hereof, to exercise any option which is herein provided, or to 
require performance of any of the provisions hereof shall in no way be construed
to be a waiver of such provisions or options.

     29.20     SUCCESSORS AND ASSIGNS. This Agreement shall be binding on and
inure to the benefit of the Parties and their respective legal successors and
permitted assigns.

     29.21     PUBLICITY. Neither Party shall use the name of the other Party in
connection with this Agreement in a press release or statement without the prior
consent of the other Party, which consent shall not be unreasonably withheld.

                                      63
     
<PAGE>
 
                                 SCHEDULE 12.3
                          SUPPORT SERVICES FOR RESALE
                          ---------------------------


1.   BA OSS SERVICES
     ---------------

     1.1 Definitions
         -----------

     As used in this Schedule 12.3, the following terms shall have the meanings 
     stated below:

     1.1.1 "BA Operations Support Systems" means BA systems for pre-ordering,
     ordering, provisioning, maintenance and repair, and billing.

     1.1.2 "BA OSS Services" means access to BA Operations Support Systems
     functions. The term "BA OSS Services" includes, but is not limited to: (a)
     BA's provision of MFS Usage Information to MFS pursuant to Section 1.3
     below; and, (b) "BA OSS Information", as defined in Section 1.1.4 below.

     1.1.3 "BA OSS Facilities" means any gateways, interfaces, databases,
     facilities, equipment, software, or systems used by BA to provide BA OSS
     Services to MFS.

     1.1.4 "BA OSS Information" means any information accessed by, or disclosed
     or provided to, MFS through or as a part of BA OSS Services. The term "BA
     OSS Information" includes, but is not limited to: (a) any Customer
     Information related to a BA Customer or an MFS Customer accessed by, or
     disclosed or provided to, MFS through or as a part of BA OSS Services: and,
     (b) any MFS Usage Information (a defined in Section 1.1.6 below) accessed
     by, or disclosed or provided to, MFS.

     1.1.5 "BA Retail Telecommunications Service" means any Telecommunications
     Service that Bell Atlantic provides at retail to subscribers that are not
     Telecommunications Carriers. The term "BA Retail Telecommunications
     Service" does not include any exchange access service (as defined in
     Section 3(16) of the Act, 47 U.S.C (Section) 153 (16)) provided by BA.

     1.1.6 "MFS Usage Information" means the usage information for a BA Retail
     Telecommunications Service purchased by MFS under this Agreement that BA
     would record if BA was furnishing such BA Retail Telecommunications Service
     to a BA end-user retail Customer.
<PAGE>
 
     1.1.7 "Customer Information" means CPNI, as defined in the Act, of a
     Customer and any other non-public, individually identifiable information
     about a Customer or the purchase by a Customer of the services or products
     of a Party.


     1.2 BA OSS Services
         ---------------

     1.2.1 Upon request by MFS, BA shall provide to MFS, pursuant to Section 
     251(c)(3) of the Act, 47 U.S.C (Section) 251(c)(3), BA OSS Services.

     1.2.2 Subject to the requirements of Applicable Laws, BA Operations Support
     Systems, BA Operations Support Systems functions, BA OSS Facilities, BA OSS
     Information, and the BA OSS Services that will be offered by BA, shall be
     as determined by BA. Subject to the requirements of Applicable Laws, BA
     shall have the right to change BA Operations Support Systems, BA Operations
     Support Systems functions, BA OSS Facilities, BA OSS Information, and the
     BA OSS Services, from time-to-time, without the consent of MFS. Except as
     otherwise provided by this Agreement or Applicable Laws, BA will give MFS
     notice in writing or electronically (which may be giving MFS access to a
     database or an Internet site that contains the applicable information, or
     by other electronic means) of material modification of the operation of BA
     OSS Services furnished under this Agreement at least sixty (60) days prior
     to the time the material modification becomes effective.


     1.3 MFS Usage Information
         ---------------------

     1.3.1 Upon request by MFS, BA shall provide to MFS, pursuant to Section 
     251(c)(3) of the Act, 47 U.S.C. (Section) 251(c)(3), MFS Usage Information.

     1.3.2 MFS Usage Information will be available to MFS through the following:

            (a) Daily Usage File on Data Tape.

            (b) Daily Usage File through Network Data Mover ("NDM").

            (c) Daily Usage File through Centralized Message Distribution System
                ("CMDS").  

     1.3.3.1 MFS Usage Information will be provided in a Bellcore Exchange
     Message Records ("EMR") format.

     1.3.3.2 Daily Usage File Data Tapes provided pursuant to Section 1.3.2(a)
     above will be issued each day, Monday through Friday, except holidays
     observed by BA.


    

    
<PAGE>
 
     1.3.4 Except as stated in this Section 1.3, subject to the requirements of
     Applicable Laws, the manner in which, and the frequency with which, MFS
     Usage Information will be provided to MFS shall be determined by BA.

     1.4   Access to and Use of BA OSS Facilities
           --------------------------------------

     1.4.1 BA OSS Facilities may be accessed and used by MFS only to the extent
     necessary for MFS's access to and use of BA OSS Services pursuant to this
     Agreement.


     1.4.2 BA OSS Facilities may be accessed and used by MFS only to provide 
     Telecommunications Services to MFS Customers.


     1.4.3 MFS shall restrict access to and use of BA OSS Facilities to MFS.
     This Schedule 12.3 does not grant to MFS any right or license to grant
     sublicenses to other persons, or permission to other persons (except MFS'S
     employees, agents and contractors, in accordance with Section 1.4.7 below),
     to access or use BA OSS Facilities.


     1.4.4 MFS shall not (a) alter, modify or damage the BA OSS Facilities
     (including, but not limited to, BA software), (b) copy, remove, derive,
     reverse engineer, or decompile, software from the BA OSS Facilities, or (c)
     obtain access through BA OSS Facilities to BA databases, facilities,
     equipment, software, or systems, which are not offered for MFS'S use under
     this Schedule 12.3.

     1.4.5 MFS shall comply with all practices and procedures established by BA
     for access to and use of BA OSS Facilities (including, but not limited to,
     BA practices and procedures with regard to security and use of access and
     user identification codes).

     1.4.6 All practices and procedures for access to and use of BA OSS
     Facilities, and all access and user identification codes for BA OSS
     Facilities: (a) shall remain the property of BA; (b) shall be used by MFS
     only in connection with MFS's use of BA OSS Facilities permitted by this
     Schedule 12.3: and, (c) shall be treated by MFS as Proprietary Information
     of BA pursuant to subsection 29.4 of the Agreement.

     1.4.7 MFS's employees, agents and contractors may access and use BA OSS
     Facilities only to the extent necessary for MFS's access to and use of the
     BA OSS Facilities permitted by this Agreement. Any access to or use of BA
     OSS Facilities by MFS's employees, agents, or contractors, shall be subject
     to the provisions of the Agreement, including, but not limited to,
     subsection 29.4 thereof and Sections 1.4.6 and 1.5.3.3 of this Schedule
     12.3.

     1.5 BA OSS Information
         ------------------
<PAGE>
 
     1.5.1 Subject to the provisions of this Agreement and Applicable Laws, BA
     grants to MFS a non-exclusive license to use BA OSS Information.

     1.5.2 All BA OSS Information shall at all times remain the property of BA.
     Except as expressly stated in this Schedule 12.3, MFS shall acquire no
     rights in or to any BA OSS Information.

     1.5.3.1 The provisions of this Section 1.5.3 shall apply to all BA OSS
     Information, except (a) MFS Usage Information, (b) CPNI of MFS, and (c)
     CPNI of a BA Customer or an MFS Customer, to the extent the Customer has
     authorized MFS to use the Customer Information.

     1.5.3.2 BA OSS Information may be accessed and used by MFS only to provide 
     Telecommunications Services to MFS Customers.

     1.5.3.3 MFS shall treat BA OSS Information that is designated by BA,
     through written or electronic notice (including, but not limited to,
     through the BA OSS Services), as "Confidential" or "Proprietary" as
     Proprietary Information of BA pursuant to subsection 29.4 of the Agreement.

     1.5.3.4 Except as expressly stated in this Schedule 12.3, this Agreement
     does not grant to MFS any right or license to grant sublicenses to other
     persons, or permission to other persons (except MFS's employees, agents or
     contractors, in accordance with Section 1.5.3.5 below), to access, use or
     disclose BA OSS Information.

     1.5.3.5 MFS's employees, agents and contractors may access, use and
     disclose BA OSS Information only to the extent necessary for MFS's access
     to, and use and disclosure of, BA OSS Information permitted by this
     Schedule 12.3. Any access to, or use or disclosure of, BA OSS Information
     by MFS'S employees, agents or contractors, shall be subject to the
     provisions of this Agreement, including, but not limited to, subsection
     29.4 of the Agreement and Section 1.5.3.3 above.

     1.5.3.6 MFS's license to use BA OSS Information shall expire upon the
     earlier of: (a) termination of the license in accordance with this Schedule
     12.3; or (b) expiration or termination of the Agreement.

     1.5.3.7 All BA OSS Information received by MFS shall be destroyed or
     returned by MFS to BA, upon expiration, suspension or termination of the
     license to use such BA OSS Information.

     1.5.4 Unless sooner terminated or suspended in compliance with the
     Agreement or this Schedule 12.3 (including, but not limited to, subsection
     22.3 of the





    
<PAGE>
 
     Agreement and Section 1.6.1 below). MFS's access to BA OSS Information
     through BA OSS Services shall terminate upon the expiration or termination
     of the Agreement.

     1.5.5.1 BA shall have the right (but not the obligation) to perform at BA's
     expense (provided that there will be no charge to BA for reasonable access
     to MFS' employees, books, records, documents and facilities) an audit of
     MFS upon three (3) full business days notice to MFS to ascertain whether
     MFS is complying with the requirements of Applicable Laws and this
     Agreement with regard to MFS's access to, and use and disclosure of, BA OSS
     Information.

     1.5.5.2 Without in any way limiting any other rights BA may have under the
     Agreement or Applicable Laws, BA shall have the right (but not the
     obligation) to monitor MFS's access to and use of BA OSS Information which
     is made available by BA to MFS pursuant to this Agreement, to ascertain
     whether MFS is complying with the requirements of Applicable Laws and this
     Agreement, with regard to MFS's access to, and use and disclosure of, such
     BA OSS Information. The foregoing right shall include, but not be limited
     to, the right (but not the obligation) to electronically monitor at BA's
     expense (provided that there will be no charge to BA by MFS to perform this
     activity), MFS's access to and use of BA OSS Information which is made
     available by BA to MFS through BA OSS Facilities.

     1.5.5.3 Information obtained by BA pursuant to this Section 1.5.5 shall be
     treated by BA as Proprietary Information of MFS pursuant to subsection 29.4
     of the Agreement; provided that, BA shall have the right (but not the
     obligation) to use and disclose information obtained by BA pursuant to this
     Section 1.5.5 to enforce BA's rights under this Agreement or Applicable
     Laws.

     1.5.6 MFS acknowledges that the BA OSS Information, by its nature, is
     updated and corrected on a continuous basis by BA, and therefore that BA
     OSS Information is subject to change from time to time.

     1.6 Liabilities and Remedies
         ------------------------

     1.6.1 Any breach by MFS, or MFS's employees, agents or contractors, of the
     provisions of Sections 1.4 or 1.5 above shall be deemed a material breach
     of the Agreement. In addition, if MFS or an employee, agent or contractor
     of MFS at any time breaches a provision of Sections 1.4 or 1.5 above and
     such breach continues for more than fifteen (15) days after written notice
     thereof from BA, then, except as otherwise required by Applicable Laws, Ba
     shall have the right, upon notice to MFS, to suspend the license to use BA
     OSS Information granted by Section 1.5.1 above and/or the provision of BA
     OSS Services, in whole or in part.
<PAGE>
 
     1.6.2 MFS agrees that BA would be irreparably injured by a breach of
     Sections 1.4 or 1.5 above by MFS or the employees, agents or contractors of
     MFS, and that BA shall be entitled to seek equitable relief, including
     injunctive relief and specific performance, in the event of any such
     breach. Such remedies shall not be deemed to be the exclusive remedies for
     any such breach, but shall be in addition to any other remedies available
     under this Agreement or at law or in equity.

     1.7 Relation to Applicable Laws
         ---------------------------

     The provisions of Sections 1.4, 1.5 and 1.6 above shall be in addition to
     and not in derogation of any provisions of Applicable Laws, including, but
     not limited to, 47 U.S.C. (S) 222, and are not intended to constitute a
     waiver by BA of any right with regard to protection of the confidentiality
     of the information of BA or BA Customers provided by Applicable Laws.

     1.8 Cooperation
         -----------

     MFS, at MFS's expense, shall reasonably cooperate with BA in using BA OSS
     Services. Such cooperation shall include, but not be limited to, the
     following:
     
     1.8.1 Upon request by BA, MFS shall by no later than the fifteenth (15th)
     day of the month preceding the first calendar month of each calendar
     quarter submit to BA reasonable, good faith estimates (by geographic area
     designated by BA) of the volume of each BA Retail Telecommunications
     Service for which MFS anticipates submitting orders in each week of the
     next calendar quarter.

     1.8.2 MFS shall participate in cooperative testing of BA OSS Services and
     shall provide assistance to BA in identifying and correcting mistakes,
     omissions, interruptions, delays, errors, defects, faults, failures, or
     other deficiencies, in BA OSS Services. The Parties will jointly agree upon
     the schedule for such testing and the tests that will be conducted.

     1.9 BA Access to Information Related to MFS Customers
         -------------------------------------------------

     BA shall have the right to access, use and disclose information related to
     MFS Customers that is in BA's possession (including, but not limited to, in
     BA OSS Facilities) to the extent such access, use and/or disclosure has
     been authorized by the MFS Customer in the manner required by Applicable
     Laws.

2.   BELL ATLANTIC PRE-OSS SERVICES
     ------------------------------

     2.1 As used in this Schedule 12.3, "BA Pre-OSS Service" means a service
     that allows the performance of an activity that is comparable to an
     activity to be performed through a BA OSS Service and that BA offers to
     provide to MFS. The term "BA Pre-OSS Service" includes, but is not limited
     to, the activity of placing






    



<PAGE>
 
     orders for BA Telecommunications Services through a telephone facsimile
     communication. Prior to purchasing BA OSS Services, MFS may purchase BA
     Pre-OSS Services.

     2.2 Subject to the requirements of Applicable Laws, the BA Pre-OSS Services
     that will be offered by BA shall be as determined by BA and BA shall have
     the right to change BA Pre-OSS Services, from time-to-time, without the
     consent of MFS. Except as otherwise provided by this Agreement or
     Applicable Laws, BA will give MFS notice in writing or electronically
     (which may be by giving MFS access to a database or an Internet site that
     contains the applicable information, or by other electronic means) of
     material modification of the operation of BA Pre-OSS Services furnished
     under this Agreement at least thirty (30) days prior to the time the
     material modification becomes effective.

     2.3 Subject to the requirements of Applicable Laws, the prices for BA Pre-
     OSS Services shall be as determined by BA and shall be subject to change by
     BA from time-to-time.

     2.4 The provisions of Sections 1.5 through 1.9 above shall also apply to BA
     Pre-OSS Services. For the purposes of this Section 2.4: (a) references in
     Sections 1.5 through 1.9 above to BA OSS Services shall be deemed to
     include BA Pre-OSS Services; and, (b) references in Sections 1.5 through
     1.9 above to BA OSS Information shall be deemed to include information made
     available to MFS through BA Pre-OSS Services.

3.   RATES AND CHARGES
     -----------------

     3.1 The prices for the foregoing services shall be as set forth in BA's
     Tariffs or, in the absence of an applicable BA Tariff price, in Exhibit A
     or, if not set forth in either, as may be determined by BA from time to
     time. If BA at any time offers a resale support service the prices for
     which are not stated in BA's Tariffs or Exhibit A and MFS elects to
     purchase such service, BA shall have the right to revise Exhibit A to add
     such prices; provided that, if the resale support service is already being
     used by MFS at the time BA revises Exhibit A to add such prices, except as
     otherwise required by this Agreement or Applicable Laws, the revision shall
     not become effective until BA has given MFS thirty (30) days prior notice
     of the revision.
<PAGE>
 

                                                                       EXHIBIT A


                BELL ATLANTIC-VIRGINIA, INC. AND MFS INTELENET
                               OF VIRGINIA, INC.


                   DETAILED SCHEDULE OF ITEMIZED CHARGES/1/
                   -------------------------------------

 A.     BA SERVICES, FACILITIES, AND ARRANGEMENTS:

<TABLE>
<CAPTION>
- ---------------------------------------------------------------------------------------------------
       BA SERVICE                                 NON-RECURRING          RECURRING
       ----------                                 -------------          ---------
- ---------------------------------------------------------------------------------------------------
<S>                                               <C>                    <C>
 1.a.  Entrance facilities, and transport, as     Per interstate [BA FCC #1 sec. 6.9.1.] and
       appropriate, for Interconnection at        (proposed) intrastate [BA-VA SCC 217
       BA End Office, Tandem Office,              sec. 6.8.2] access tariffs for Feature Group
       Serving Wire Center, or other Point        D Service/2/
       of Interconnection

                                                  Illustrative:

                                                    Interstate non-recurring: $1, plus $1
                                                  switched access connection charge per
                                                  trunk; DS-1 entrance facility $210-
                                                  $212/mo.

                                                    Intrastate nonrecurring: $895 for first DS-
                                                  1, $280 for additional, plus $25 switched
                                                  access connection charge per trunk; DS-1
                                                  entrance facility $270/mo.
- ---------------------------------------------------------------------------------------------------
 1.b.  Collocation and related services for       Per interstate [BA FCC 1 sec. 19] and
       Interconnection at BA End Office,          intrastate access tariffs/3/
       Tandem Office, or Serving Wire
       Center
- ---------------------------------------------------------------------------------------------------
</TABLE>

___________________
/1/       Rates listed herein for services, facilities, or arrangements that are
marked with an asterisk (*) are fixed pursuant to Section 20 of the Agreement
for the initial term of the Agreement, as set forth in Section 22 of the
Agreement. Rates for services, facilities, or arrangements that are not marked
with an asterisk shall change in accordance with the provisions of Section 20 of
the Agreement.
/2/       Pending approval of the BA intrastate local transport restructure
tariff, intrastate access services subject to the pending tariff will be charged
pursuant to effective tariffs, as agreed by the Parties, subject to true-up at
either Party's request.
/3/       Pending approval of the BA intrastate collocation tariff to be filed
no later December 31, 1996, all collocation services shall be charged at rates
found in BA FCC 1 sec. 19.

                                       1
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------------------------------
     BA SERVICE                        NON-RECURRING                           RECURRING
     ----------                        -------------                           ---------
- ------------------------------------------------------------------------------------------------------------------------------------
<S>                                    <C>                                     <C> 
1.c. Tandem transit arrangements       Per tariffs cited in    
     (for Interconnection between      sections 1.a. and 1.b. above, as        Per interstate [BA FCC 1 sec. 6.9.1.B] and      
     MFS and carriers other than BA)   applicable; separate trunks required    (proposed) intrastate [BA-VA SCC 217 sec. 6.8.2.B]
                                       for IXC subtending trunks/4/            for tandem switching and tandem switched transport,
                                                                               as applicable/5/   
                                                                               

                                                                               Illustrative:
                                     
                                                                                Interstate, (proposed) intrastate tandem switching 
                                                                               $.000999/mou, tandem switched transport $.000195/mou
                                                                               plus $.000045/mou/mile
- ------------------------------------------------------------------------------------------------------------------------------------
1.d. 911 Interconnection               Per tariffs cited in 1.a., 1.b., and 1.c. above, as applicable, for entrance facility plus
                                       applicable transport, or Collocation Arrangement at 911 tandem
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 


________________________________
/4/    See note 2 above.
/5/    See note 2 above.

                                       2

                                                                 
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------------------------------------------
      BA SERVICE                                NON-RECURRING                            RECURRING
      ----------                                -------------                            ---------
- ------------------------------------------------------------------------------------------------------------------------------------
<S>                                             <C>                                      <C> 
1.e.  Directory assistance Interconnection      Intrastate per (proposed) BA-VA SCC      Intrastate per (proposed) BA-VA SCC 217
                                                217 sec. 9.6.B (transport)/6/            sec. 9.6.B:  
                                                
                                                                                         Illustrative: 

                                                                                           Per call rate $.000092 fixed, $.000021
                                                                                         per mile, $.000462 tandem switching,
                                                                                         $.003705 interconnection

                                                Interstate per BA FCC 1 sec. 9.6.B       Interstate per BA FCC 1 sec. 9.6.B 

                                                                                         Illustrative: 

                                                                                           Per call rate $.000082 fixed, $.000019
                                                                                         per mile, $.000353 tandem switching, 
                                                                                         $.002311 interconnection
- ------------------------------------------------------------------------------------------------------------------------------------
1.f.  Operator services (call completion)       Per separate contract
      Interconnection
- ------------------------------------------------------------------------------------------------------------------------------------
2.    Unbundled elements                        Available as listed herein and in interstate and intrastate tariffs, and pursuant
                                                to Section 11. of the Agreement
- ------------------------------------------------------------------------------------------------------------------------------------
3.    Poles, ducts, conduits, ROW               Per contract rates pursuant to 47 U.S.C. sec. 224
                         
                                                Illustrative:

                                                  Duct (Northern Virginia) $4.50/ft/yr.
                                                  Pole $4.46/attachment/yr.
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE> 


____________________________________
/6/   See note 2 above
/7/   See note 2 above.

                                       3
<PAGE>
 
<TABLE> 
 <CAPTION> 
- --------------------------------------------------------------------------------
     BA SERVICE                 NON-RECURRING              RECURRING
     ----------                 -------------              ---------
- --------------------------------------------------------------------------------
<S>  <C>                        <C>                        <C> 
4.a. Local loop transmission*   Permanent rates to be      Permanent rates to be 
                                determined by appropriate  determined by appropriate
       Unbundled Local Loop     arbitral body. Interim     arbitral body. Interim   
       Element                  rates will apply until     rates will apply until   
                                the permanent rates are    the permanent rates are 
       Cross Connection to      determined./8/             determined./9/           
       POTS loop                                                                
                                                                               

- --------------------------------------------------------------------------------
4.b. Special construction       As applicable per BA-VA SCC 203 sec. 2
     charges
- --------------------------------------------------------------------------------
4.c. Central office technician  Per interstate [BA FCC 1 sec. 13.2 or sec. 19.5]
     charges (during normal     tariff.
     working hours)

- --------------------------------------------------------------------------------
5.a. Trunk Side local      
     transport

       DS-1 transport         Per interstate [BA FCC 1 sec. 6.9.1.C] and 
                              (proposed) intrastate [BA-VA SCC 217 sec. 6.8.2.C]
                              tariffs
                    
                              Illustrative recurring:

                                Interstate $60/mo. fixed, $17.70/mile/mo.

                                Intrastate $75/mo. fixed, $30/mile/mo.
- --------------------------------------------------------------------------------
5.b. DS-3 transport           Tariff reference see 5.a. above.

                              Illustrative recurring:

                                Interstate, intrastate $900/mo. fixed, 
                              $180/mile/mo.
- --------------------------------------------------------------------------------
</TABLE> 

_______________________
/8/  Interim rates will be based on the following order of precedence (i)
effective tariff(s), (ii) other BA ILEC-CLEC Interconnection Agreement(s) in the
state, (iii) any Commission recommendation, or (iv) mutual agreement of the
Parties.

/9/  See preceding note.
/10/ See note 2 above.

                                       4

<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICES                 NON-RECURRING                 RECURRING  
     -----------                 -------------                 ---------
- --------------------------------------------------------------------------------
6.   Local switching*  

      POTS switch Port            $6/service order              $1.50/mo., plus
                                 plus $6/Port                  usage per tariff,
                                                               minus wholesale
                                                               discount per 
                                                               section 14 below
- --------------------------------------------------------------------------------
7.a. Operator services

      911 service (data entry;   No charge  
     database maintenance)*
- --------------------------------------------------------------------------------
7.b.  Directory assistance       Per tariff or separate        Per tariff or  
                                 contact; branding             separate contract
                                 available
                                                               Illustrative 
                                                               tariff rates:

                                                               Interstate [BA 
                                                               FCC 1 sec. 9.6],
                                                               $.275-.288 per 
                                                               call 

                                                               Intrastate 
                                                               (proposed) [BA-VA
                                                               SCC 217 sec. 9.6.
                                                               A], $.25 per call

                                                               Directory 
                                                               transport per 
                                                               section 1.e. 
                                                               above
- --------------------------------------------------------------------------------
7.c.  Operator call              Per separate contract; branding available     
      completion
- --------------------------------------------------------------------------------
8.a. White pages directory       $5.00 per primary listing     No charge 
     listings*                   per number
- --------------------------------------------------------------------------------
8.b.  Books & delivery           No charge for normal numbers of books delivered
     (annual home area           to end users: bulk deliveries to CLEC per
     directories only)*          separate arrangement 
- --------------------------------------------------------------------------------

                                       5

<PAGE>
 

<TABLE> 
<CAPTION> 
- ----------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ----------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
8.c.  Additional listings, changes           Per tariff [BA-VA              Per tariff [BA-VA SCC 
     to listing, non-listed, non-            SCC 203 sec. 4]                203 sec. 4]
     published, and other extra services
                                             Illustrative:                  Illustrative:

                                              Additional listing:           Additional listing:  
                                             $9 residence: $17              $1.12/mo. residence, 
                                             business                       $1.42/mo. business    
                                                                            
                                              Change to listing:           
                                             $9 residence: $17              Non-list:            
                                             business                       $1.06//mo. residence 
                                                                            or business           
                                              Non-list:                    
                                             $9 residence: $17              Non-published:     
                                             business                       $1.71/mo. residence
                                                                            or business         
                                              Non-published:
                                             $9 residence: $17
                                             business
- ---------------------------------------------------------------------------------------------------- 
9.   Access to telephone numbers (NXX
     codes issued per ICCF Code              No charge
     Administration Guidelines)*        
- ----------------------------------------------------------------------------------------------------  
10.a SS7 Interconnection                     Per interstate [BA             Per interstate [BA
                                             FCC 1 sec. 6.9.1.G]            FCC 1 sec. 6.9.1.L]
                                             and intrastate [BA-            and intrastate [BA-
                                             VA SCC 217 sec.                VA SCC 217 sec.
                                             6.8.2.C] tariff                6.8.2.G] tariff 

     
                                                                            Illustrative:
          
                                                                             STP ports,
                                                                            $900/mo.;
                              
                                                                             STP access,
                                                                            $3.50/mile/mo. to
                                                                            $5.72/mile/mo.
- ----------------------------------------------------------------------------------------------------
</TABLE> 
  
                                       6
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
10.b LIDB Interconnection                    Per tariff [BA FCC             Per tariff [BA FCC 
                                             1 sec. 6.9.1M]                 1 sec. 6.9.1M]     
          
                                             Illustrative:                  Illustrative:
                              
                                              Originating point              Query validation
                                             code, $125                     $.04/query

                                                                             Query transport
                                                                            $.0002/query
- ------------------------------------------------------------------------------------------------
10.c 800/888 data base Interconnection       No separate charge             Per interstate [BA
                                             (included in FGD               FCC 1 sec.
                                             trunk and STP links)           6.9.2.A.1], and
                                                                            intrastate [BA-VA
                                                                            SCC 217 sec.
                                                                            6.8.2.K]tariffs

                                                                            Illustrative:

                                                                             Interstate basic
                                                                            query,
                                                                            $.003105/query;
                                                                            vertical feature
                                                                            package,
                                                                            $.000337/query

                                                                             Intrastate basic 
                                                                            query,
                                                                            $.003089/query;
                                                                            vertical feature
                                                                            package,
                                                                            $.000327/query
- ------------------------------------------------------------------------------------------------
11.a Interim number portability through      service order per              $3/mo. per number
     co-carrier call forwarding              location $30                   for up to 10 paths;
                                                                            $.40/mo. per 
                                             installation per               additional path
                                             number $35 (unless
                                             installed with 
                                             unbundled loop)
               
                                             installation per 
                                             separate path
                                             arrangement $20
- ------------------------------------------------------------------------------------------------
</TABLE> 

                                       7
<PAGE>
 
<TABLE> 
<CAPTION> 
- ------------------------------------------------------------------------------------------------
     BA SERVICE                              NON-RECURRING                  RECURRING
     ----------                              -------------                  ---------
- ------------------------------------------------------------------------------------------------
<S>  <C>                                     <C>                            <C> 
11.b  Access pass-through to number                                         In accordance with
     portability purchaser*                                                 section 14.5 of
                                                                            Agreement.
- ------------------------------------------------------------------------------------------------
12.  Local dialing parity*                   No charge
- ------------------------------------------------------------------------------------------------
13.a Reciprocal call termination

      Local Traffic delivered to Bell
     Atlantic Interconnection Point

      First year*               
                                                                            $.009/mou
    -------------------------------------------------------------------------------------------- 
      After first year*                                                     In accordance with 
                                                                            note 14 below
- ------------------------------------------------------------------------------------------------
13.b  Access charges for termination of                                     Per interstate and
     intrastate and interstate Toll Traffic                                 intrastate access
                                                                            tariffs (charged in
                                                                            conjunction with
                                                                            Local Traffic, using
                                                                            PLU and PIU, as 
                                                                            appropriate)
- ------------------------------------------------------------------------------------------------
14.a Wholesale rates for resale of           Percentage discount from retail tariff/12/
                                             --------------------------------------
     telecommunications services
     provided to end users/11/
- ------------------------------------------------------------------------------------------------
14.b Resale of retail Telecommunications     21.3% or discount as determined by further
     Services if MFS provides its own        Commission order.
     Operator Services

- ------------------------------------------------------------------------------------------------
14.c Resale of retail Telecommunications     18.5% or discount as determined by further
     Services if MFS uses BA Operator        Commission order.
     Services.
- ------------------------------------------------------------------------------------------------
</TABLE> 


____________________

/11/      Excludes telecommunications services designated primarily for
wholesale, such as switched and special access, and, subject to Section 12 of
the Agreement, the following additional arrangements that are not subject to
resale: limited duration (90 days or less) promotional offerings, public coin
telephone services, and technical and market trials. Taxes shall be collected
and remitted by the reseller and BA in accordance with legal requirements and as
agreed between the Parties. Surcharges (e.g., 911, telecommunications relay
service, universal service fund) shall be collected by the reseller and either
remitted to the recipient agency or NECA, or passed through to BA for remittance
to the recipient agency or NECA, as appropriate and agreed between the Parties.
End user common line charges shall be collected by the resellers and remitted to
BA.

/12/      Pending establishment of mechanized billing procedures adapted to 
resale, the Parties will agree upon a composite "bottom-of-the-bill" discount 
that reflects the discounts and exclusions identified herein, and such other 
adjustments as the Parties agree.

                                       8

<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING            RECURRING
     ----------                    -------------            ---------
- --------------------------------------------------------------------------------
15.  Access to BA OSS/13/          
- --------------------------------------------------------------------------------
15.a Access to Pre-Ordering OSS                             $.26/Query
- --------------------------------------------------------------------------------
15.  Access to Ordering OSS                                 $4.53/Transaction
b
- --------------------------------------------------------------------------------
15.c Access to Provisioning OSS                             Included in Ordering
- --------------------------------------------------------------------------------
15d  Access to Maintenance &                                $1.23/Trouble Ticket
     Repair OSS
- --------------------------------------------------------------------------------
15e. Access to Billing OSS; CD-ROM                          $261.04/CD-ROM
1
- --------------------------------------------------------------------------------
15.e Access to Billing OSS; Daily 
 .2   Usage File
       Existing Message Recording                     
 
                                                            $.000274/Message
- --------------------------------------------------------------------------------
15.e Access to Billing OSS; Daily
     Usage
 .3   File Delivery
       Data Tape                   $64.96/Programming Hour  $20.11/Tape

       Network Data Mover          Not Applicable           $.000099/Message

       CMDS                        $64.96/Programming Hour  $.000099/Message
- --------------------------------------------------------------------------------
15.e Access to Billing OSS; Daily  
     Usage
 .4   File Transport
       9.6 kb Communications Port  $8,335.27/Port           $10.84/Month
- --------------------------------------------------------------------------------

___________________
/13/ The rates for BA OSS Services that appear in Section 15 above shall apply 
until the earlier of August 15, 1997 or the date the Commission approves rates 
for BA OSS Services. If the Commission approves rates for BA OSS Services on or 
before August 15, 1997, the rates approved by the Commission will apply from the
date they are approved by the Commission until any subsequent change in rates 
becomes effective in accordance with this Agreement.

     If by August 15, 1997 the Commission has not approved rates for BA OSS 
Services, from August 16, 1997 until such time as the Commission approves rates
for BA OSS Services, BA will track the usage of BA OSS Services by MFS. When 
the Commission approves rates for BA OSS Services, those rates will apply from 
August 16, 1997 until any subsequent change in rates becomes effective in 
accordance with this Agreement.

     MFS reserves the right to at any time prior to the above-mentioned 
Commission approval of rates for BA OSS Services initiate or participate in a 
proceeding before the Commission or other governmental entity of appropriate 
jurisdiction to obtain a determination as to the lawfulness of the rates stated 
above in Section 15 for Bell Atlantic OSS Services. However, until such time as 
the Commission or other governmental entity of appropriate jurisdiction, in an 
order that is binding upon Bell Atlantic, requires Bell Atlantic to change or 
delete the rates stated above in Section 15 for Bell Atlantic OSS Services,
MFS agrees to pay such rates as provided in this Footnote.

     When rates for BA OSS Services are approved by the Commission Section 15 
above shall be amended by the Parties to state such rates.

                                       9
<PAGE>
 
- --------------------------------------------------------------------------------
     BA SERVICE                    NON-RECURRING                 RECURRING
     ----------                    -------------                 ---------
- --------------------------------------------------------------------------------
       56 kb Communications Port   $34,494.62/Port               $29.93/Month

       256 kb Communications Port  $57,422.87/Port               $29.93/Month
       
       T1 Communications Port      $204,901.39/Port              $380.18/Month

       Line Installation           $64.96/Programming Hour/Port  Not applicable

       Port Set-up                 $10.43/Port                   Not applicable

       Network Control Programming $64.96/Programming Hour/Port  Not applicable
       Coding
- --------------------------------------------------------------------------------

                                      10

<PAGE>
 
           MFS SERVICES, FACILITIES, AND ARRANGEMENTS:
- --------------------------------------------------------------------------------
          MFS SERVICE                   NON-RECURRING            RECURRING
          -----------                   -------------            ---------
- --------------------------------------------------------------------------------
1.a.      Interim Number Portability    
          through co-carrier call 
          forwarding*
      
           Number portability*          $30/service order.       $3/mo. for ten 
                                        $35/number (not ordered  paths per 
                                        with ULL)                number; plus 
                                                                 $.40/mo.per 
                                                                 additional path

                                        $20 per additional path
                                        order
- --------------------------------------------------------------------------------
1.b.      Access pass-through to number                          In accordance 
         portability purchaser*                                  with sec. 14.5 
                                                                 of Agreement
- --------------------------------------------------------------------------------
2.       Local dialing parity*          No charge
- --------------------------------------------------------------------------------
3.a.     Reciprocal call termination

          Local Traffic delivered to  
          MFS Interconnection Point*

           First year*                                           $.009/mou
         -----------------------------------------------------------------------
           After first year*                                     In accordance 
                                                                 with note 14 
                                                                 below
- --------------------------------------------------------------------------------
3.b.      Access charges for                                     Per MFS 
         termination of intrastate and                           interstate and
         interstate Toll Traffic                                 intrastate
                                                                 access rates
                                                                 (charged in
                                                                 conjunction
                                                                 with Local
                                                                 Traffic, using
                                                                 PLU and PIU, as
                                                                 appropriate)
- --------------------------------------------------------------------------------
4.       All other MFS services         Available at MFS tariffed or otherwise
         available to BA for purposes   generally available rates, not to exceed
         of effectuating local          BA rates for equivalent services  
         exchange competition           available to MFS 
- --------------------------------------------------------------------------------
5.        Other Services

         Information Service billing    No charge                $.03 per call
         fee    
- --------------------------------------------------------------------------------

                                      11

<PAGE>
 
A.   Charges by BA
     -------------
     (a)  Traffic delivered to BA Local Serving Wire Center ("LSWC") or BA
          Access Tandem: $.009 per mou
     (b)  Traffic delivered directly to terminating BA End Office: $.007 per mou
     Note: All BA-IPs identified in Schedule 4.0 as of the Effective Date are 
     LSWC or Access Tandems. Therefore, Local Traffic delivered to such BA-IPs 
     shall be subject to the rate of $.009 per mou.

B.   Charges by MFS
     --------------
1.   Single-tiered interconnection structure:
     MFS's rates for the termination of BA's Local Traffic under the 
     single-tiered interconnection structure shall be recalculated once each 
     year on each anniversary of the Effective Date (the "Rate Determination 
     Date"). The initial Rate Determination Date shall be the first anniversary 
     of the Effective Date. The methodology for recalculating the rates is as 
     follows:
          LSWC/Access Tandem Minutes = Total minutes of use of Local Traffic
          delivered by MFS to the BA LSWC or BA Access Tandem for most recent
          billed month.
          End Office Minutes = Total minutes of use Local Traffic delivered by
          MFS directly to the terminating BA End Office for most recent billed
          month. 
          Total Minutes = Total minutes of use of Local Traffic delivered by 
          MFS to BA for most recent billed month.
          MFS Charge at the M-IP = (LSWC/Access Tandem Minutes X $.009) + (End
          Office Minutes X $.007)
          -------------------------------------------------------------------
                                 Total Minutes

2.   Multiple-tiered interconnection structure (if offered by MFS to any 
     carrier)
     (a) Local Traffic delivered to MFS LSWC or MFS Access Tandem: $.009
     (b) Local Traffic delivered to terminating MFS End Office/node: $.007

C.   Miscellaneous Notes
     -------------------
1.   In the event a Party desires to deliver Local Traffic to a LSWC (i) that is
not located within 25 miles of the Tandem Office to which it is subtended,
and/or (ii) where the Tandem Office that it subtends is not located within 25
miles of the Tandem Office that is subtended by the terminating End Office, then
such Party shall (x) in addition to paying the LSWC/Access Tandem termination
rate described above, purchase the necessary facilities from the terminating
Party to transport such Traffic to a qualifying LSWC or Access Tandem that is
not subject to either conditions (i) or (ii) above, (y) purchase such other
service(s) as the terminating Party may offer under applicable tariff to remedy
such condition(s), or (z) enter into a new compensation arrangement as the
Parties may agree. Notwithstanding the foregoing, nothing in this Agreement
shall obligate BA to provide switching services at a LSWC when it functions as
such.

                                      12 





   
<PAGE>
 
2.   In the event the two-tiered rate structure described above is modified
pursuant to Applicable Law to a single rate structure. BA and MFS (to the extent
MFS is offering a multiple-tiered interconnection structure) shall each have the
right to apply its tariffed switched access transport charges for transporting
Local Traffic it receives at its LSWC to the first point of switching in its
network in the LATA.

3.   The MFS termination rate under the single-tiered interconnection structure
set forth above is intended by the Parties to be a Local Traffic termination 
rate for Interconnection to the M-IP within each LATA that is reciprocal and 
equal to the actual rates that will be charged by BA to MFS under the 
two-tiered Local Traffic termination rate structure described above that will 
apply after the first anniversary of the Effective Date. The single MFS 
termination rate is also intended to provide financial incentives to MFS to 
deliver traffic directly to BA's terminating End Offices once MFS's traffic 
volumes reach an appropriate threshold. The Parties agree that the Reciprocal 
Compensation rate(s) set forth herein recover a reasonable approximation of 
each Party's additional costs of terminating calls that originate on the 
network facilities of the other Party.

                                      13

  




<PAGE>
 
SCHEDULE 3.0

NETWORK IMPLEMENTATION SCHEDULE FOR VIRGINIA

     In accordance with the provisions of Section 3 of the Agreement, the 
Parties shall make their best efforts to meet the following Milestones no later 
than the listed Dates.

- --------------------------------------------------------------------------------
 LATA IN VIRGINIA     MILESTONE                                      DATE
- --------------------------------------------------------------------------------
 LATA 236             LATA Start Date ("SD")                         7/21/98
                      ----------------------------------------------------------
                      SS7 Certification, Collocation, and NXX(s)     8/19/98
                      Applied For
                      ----------------------------------------------------------
                      Parties Agree on Initial Network Design        8/24/98
                      ----------------------------------------------------------
                      Valid Access Service Request(s) ("ASRs") and   TBD
                      Routing Information Received by BA
                      ----------------------------------------------------------
                      Collocation Arrangements Complete for Trunk    N/A
                      Interconnection and IDLC for ULLs
                      ----------------------------------------------------------
                      All Trunks Tested and Turned Up; SS7 Certifi-  11/20/98
                      cation Achieved; /1/  VG ULL Capability 
                      Available
                      ----------------------------------------------------------
                      Call-through Testing Completed;                12/11/98  
                      "Interconnection Activation Date"  
- --------------------------------------------------------------------------------
                           

     Failure of a Party or the Parties to meet an earlier Milestone Date shall
not relieve either Party of the responsibility to make its best efforts to meet
subsequent Milestone Date(s) in the LATA, unless, and only to the extent that,
the subsequent Milestone Date(s) depend on the timely completion of such earlier
Milestone Date.

     For purposes of Section 3, (i) business Telephone Exchange Service shall be
considered "fully operational" in a LATA in the Commonwealth of Virginia when
Focal has an effective Tariff for business Telephone Exchange Service in the
Commonwealth of Virginia and has a significant number of Telephone Exchange
Service in the Commonwealth of Virginia and has a significant number of 
Telephone Exchange Service  Customer lines in service for business Telephone 
Exchange Service Customers in that LATA in the Commonwealth of Virginia that 
are not affiliates or employees of either BA or Focal, and (ii) residential 
Telephone Exchange Service shall be considered "fully operational" in a LATA 
in the Commonwealth of Virginia when Focal has an effective Tariff for 
residential Telephone Exchange Service in the Commonwealth of Virginia and 
has a significant number of Telephone Exchange Service Customer lines in service
for residential Telephone Exchange Service Customers in that LATA in the
Commonwealth of Virginia that are not affiliates or employees of either BA or 
Focal.

_____________________________
/1/  SS7 certification scheduling depends on actual schedule availability at
     time of request.

                                       1


<PAGE>
 
SCHEDULE 4.0

VIRGINIA - INTERCONNECTION POINTS IN LATA



                                   LATA 236
                                   --------

F-IP:      Washington D.C. Switch
           1120 Vermont Ave. N.W.  
           Washington, D.C.
           WASHDCRKDS2

BA-IP      WorldCom COLO
           1025 N. Irving Street
           Arlington, VA
           ARTNVAARHVA



<PAGE>
 
                                                                  Exhibit 10.4


                 FOCAL COMMUNICATIONS CORPORATION OF WASHINGTON

                                      AND

                         U S WEST COMMUNICATIONS, INC.

                           ARBITRATED INTERCONNECTION
                                   AGREEMENT

                          FOR THE STATE OF WASHINGTON


                                Agreement Number
                                CDS-990114-0031

                 Focal Communications Corporation of Washington
             Is opting into the Electric Lightwave, Inc. Agreement
<PAGE>
 
                               TABLE OF CONTENTS
I.  RECITALS                                                               1
II. SCOPE OF AGREEMENT                                                     1
III.DEFINITIONS                                                            2
IV. RATES AND CHARGES GENERALLY                                            8
V.  RECIPROCAL TRAFFIC EXCHANGE                                            8
 A. Scope                                                                  8
 B. Types of Traffic                                                       8
 C. Types of Exchanged Traffic                                             9
 D. Rate Structure -- Local Traffic                                        11
 E. Rate Structure -- Toll Traffic                                         12
 F. Rate Structure -- Transit Traffic                                      12
 G. LIS Interface Code Availability And Optional Features                  12
 H. Measuring Local Interconnection Minutes                                13
 I. Testing                                                                14
 J. Ordering                                                               14
 K. Billing Arrangements                                                   15
 L. Mileage Measurement                                                    16
 M. Construction Charges                                                   16
VI. INTERCONNECTION                                                        16
 A. Definition                                                             16
 B. Mid-span Meet POI                                                      17
 C. Collocation                                                            17
 D. Entrance Facility                                                      17
 E. Quality of Interconnection                                             17

                                     Page 1
<PAGE>
 
                               TABLE OF CONTENTS

 F.   Points of Interface (POI)                                            17
 G.   Trunking Requirements                                                18
 H.   Service Interruptions                                                19
 I.   Interconnection Forecasting                                          20
VII.  COLLOCATION                                                          21
 A.   General Provisions                                                   21
 B.   Virtual Collocation                                                  22
 C.   Physical Collocation                                                 24
 D.   Collocation Rate Elements                                            26
 E.   Collocation Installation Intervals                                   29
VIII. INTERIM NUMBER PORTABILITY                                           30
 A.   General Terms                                                        30
 B.   Description of Service                                               31
IX.   DIALING PARITY                                                       35
X.    ACCESS TO TELEPHONE NUMBERS                                          35
XI.   CALL COMPLETION FROM USWC OPERATORS                                  36
XII.  BUSY LINE VERIFY INTERRUPT                                           36
XIII. TOLL AND ASSISTANCE OPERATOR SERVICES                                37
XIV.  DIRECTORY ASSISTANCE                                                 38
XV.   DIRECTORY LISTINGS                                                   39
XVI.  U S WEST DIRECT ISSUES                                               41
XVII. ACCESS TO POLES, DUCTS, CONDUITS, AND RIGHTS OF WAY                  41
XVIII. ACCESS TO DATABASES                                                 41


                                     Page 2
<PAGE>
 
                               TABLE OF CONTENTS

XIX.   NOTICE OF CHANGES                                                   42
XX.    9111E-911 SERVICE                                                   42
XXI.   REFERRAL ANNOUNCEMENT                                               44
XXII.  COORDINATED REPAIR CALLS                                            44
XXIII. NETWORK INTERCONNECTION AND UNBUNDLED ELEMENT REQUEST.              44
XXIV.  AUDIT PROCESS                                                       46
XXV.   AUDIOTEXT AND MASS ANNOUNCEMENT SERVICES                            47
XXVI.  LOCAL INTERCONNECTION DATA EXCHANGE FOR BILLING                     48
XXVII. SIGNALING ACCESS TO CALL-RELATED DATABASES                          49
XXVIII. INTERCONNECTION TO LINE INFORMATION DATABASE (LIDB)                50
XXIX.  CONSTRUCTION CHARGES                                                51
XXX. RESALE                                                                52
 A. Description                                                            52
 B. Scope                                                                  52
 C. Ordering and Maintenance                                               52
 D. Focal Responsibilities                                                 54
 E. Rates and Charges                                                      55
 F. Directory Listings                                                     56
 G. Deposit                                                                56
 H. Payment                                                                57
XXXI. UNBUNDLED ACCESS ELEMENTS                                            58
 A. General Terms                                                          58
 B. Description of Unbundled Elements                                      58


                                     Page 3
<PAGE>
 
                               TABLE OF CONTENTS

XXXII.  SERVICE STANDARDS                                                  64
XXXIII. IMPLEMENTATION SCHEDULE                                            65
XXXIV.  MISCELLANEOUS TERMS                                                66
 A.     General Provisions                                                 66
 B.     Most Favored Nation Terms and Treatment                            67
 C.     Letter of Authorization                                            67
 D.     Payment                                                            67
 E.     Taxes                                                              67
 F.     Intellectual Property                                              68
 G.     Severability                                                       68
 H.     Responsibility for Environmental Contamination                     69
 I.     Responsibility of Each Party                                       69
 J.     Referenced Documents                                               69
 K.     Publicity and Advertising                                          70
 L.     Executed in Counterparts                                           70
 M.     Headings of No Force or Effect                                     70
 N.     Entire Agreement                                                   70
 0.     Joint Work Product                                                 70
 P.     Disclaimer of Agency                                               70
 Q.     Survival                                                           71
 R.     Effective Date                                                     71
 S.     Amendment of Agreement                                             71
 T.     Indemnity                                                          71
 U.     Limitation of Liability                                            72
 V.     Term of Agreement                                                  73

                                     Page 4
<PAGE>
 
                               TABLE OF CONTENTS

 W.     Controlling Law                                                    73
 X.     Cancellation Charges                                               73
 Y.     Regulatory Approval                                                73
 Z.     Compliance                                                         73

 AA.    Compliance with the Communications Law Enforcement Act of 1994
        ("CALEA")                                                          73
 BB.    Independent Contractor                                             74
 CC.    Force Majeure                                                      74
 DD.    Dispute Resolution                                                 74
 EE.    Commission Decision                                                74
 FF.    Nondisclosure                                                      74
 GG.    Notices                                                            76
 HH.    Assignment                                                         76
 II.    Warranties                                                         76
 JJ.    Default                                                            77
 KK.    No Third Party Beneficiaries                                       77
APPENDIX A -  RATES AND CHARGES                                            79
APPENDIX B - ENGINEERING REQUIREMENTS                                      1
APPENDIX C -  PHYSICAL COLLOCATION AGREEMENT                               1
ARTICLE I -  PREMISES                                                      3
ARTICLE II - EFFECTIVENESS AND REGULATORY APPROVAL                         4
ARTICLE III - TERM                                                         5
ARTICLE IV -  PREMISES CHARGES                                             7
ARTICLE V -  INTERCONNECTION CHARGES                                       7
ARTICLE VI - DEMARCATION POINT                                             7


                                     Page 5
<PAGE>
 
                               TABLE OF CONTENTS

ARTICLE VII -  USE OF PREMISES                                             8
ARTICLE VIII - STANDARDS                                                   9
ARTICLE IX -  RESPONSIBILITIES OF THE INTERCONNECTOR AND USWC              9
ARTICLE X - QUIET ENJOYMENT                                                11
ARTICLE XI - ASSIGNMENT                                                    11
ARTICLE XII -CASUALTY LOSS                                                 11
ARTICLE XIII -  LIMITATION OF LIABILITY                                    12
ARTICLE XIV -  SERVICES, UTILITIES, MAINTENANCE AND FACILITIES             13
ARTICLE XV- DISPUTE RESOLUTION                                             13
ARTICLE XVI - SUCCESSORS BOUND                                             13
ARTICLE XVII - CONFLICT OF INTEREST                                        13
ARTICLE XVIII - NON-EXCLUSIVE REMEDIES                                     14
ARTICLE XIX - NOTICES                                                      14
ARTICLE XX - COMPLIANCE WITH LAWS                                          14
ARTICLE XXI- INSURANCE                                                     14
ARTICLE XXII- US WEST'S RIGHT OF ACCESS                                    15
ARTICLE XXIII- OTHER COLLOCATION AGREEMENTS                                15
ARTICLE XXIV - MISCELLANEOUS                                               15



                                     Page 6
<PAGE>
 
                           INTERCONNECTION AGREEMENT

     THIS INTERCONNECTION AGREEMENT, made as of this 15th day of January, 1999,
is between Focal Communications Corporation of Washington ("Focal") and U S WEST
Communications, Inc. ("USWC"), a Colorado corporation.

I.   RECITALS

     Pursuant to this Interconnection Agreement Focal Communications Corporation
     of Washington. ("Focal") and U S WEST Communications, Inc. ("USWC"),
     collectively "the Parties", will extend certain arrangements to one another
     within each LATA in which they both operate within this State. This
     Agreement is a combination of agreed terms and terms imposed by arbitration
     under Section 252 of the Communications Act of 1934, as modified by the
     Telecommunications Act of 1996 ("the Act"), and as such does not
     necessarily represent the position of either Party on any given issue. The
     Parties enter into this Agreement without prejudice to any position they
     may have taken previously, or may take in the future in any legislative
     regulatory, or other public forum addressing any matters, including matters
     related to the types of arrangements prescribed by this Agreement.

II.  SCOPE OF AGREEMENT

     A.   This Agreement sets forth the terms, conditions and prices under which
          USWC agrees to provide (a) services for resale (hereinafter referred
          to as "Local Services") (b) certain Unbundled Network Elements,
          Ancillary Functions and additional features to Focal (hereinafter
          collectively referred to as "Network Elements") or combinations of
          such Network Elements ("Combinations") for Focal's own use or for
          resale to others. The Agreement also sets forth the terms, conditions
          and prices under which the parties agree to provide interconnection
          and reciprocal compensation for the exchange of local traffic between
          USWC and Focal for purposes of offering telecommunications services.
          Unless otherwise provided in this Agreement, the parties will perform
          all of their obligations hereunder throughout, to the extent provided
          in the Appendices attached hereto. The Agreement includes all
          accompanying appendices.

     B.   In the performance of their obligations under this Agreement, the
          Parties shall act in good faith and consistently with the intent of
          the Act. Where notice, approval or similar action by a Party is
          permitted or required by any provision of this Agreement, (including,
          without limitation, the obligation of the parties to further negotiate
          the resolution of new or open issues under this Agreement) such action
          shall not be unreasonably delayed, withheld or conditioned.

     C.   When Focal begins offering residential and business exchange services
          in this state through the use of Focal's facilities, Focal will notify
          USWC.

                                     Page 1
<PAGE>
 
     D.   Acknowledgment of Deferred Issues:

          Focal acknowledges it is USWC's position that USWC's existing
          telecommunications network represents substantial investment made as a
          result of its carrier-of-last-resort obligation and that such network
          allows Focal's end users to interconnect with significantly more
          business and residential customers than vice versa. Focal further
          acknowledges USWC believes that a separate transitional element is
          necessary to compensate USWC for the value of its network in this
          Agreement, that under the Act, the FCC will establish a proceeding to
          address Universal Service Support, and that the Act also empowers the
          state Commission to establish a separate proceeding on universal
          service issues. Focal further acknowledges that USWC believes that
          USWC is entitled to receive additional compensation for costs of
          implementing various provisions of the Act, and that USWC shall seek
          such additional recovery through future state and/or federal
          regulatory proceedings. Focal disagrees with these USWC positions.

          USWC acknowledges it is Focal's position that the relative investments
          of the Parties is not a relevant consideration in the context of this
          agreement and that it is the result of a historical monopoly which
          confers significant, continuing benefits on USWC. USWC acknowledges
          that it is Focal's position that no transitional elements are
          necessary to compensate USWC, that any such transitional elements
          would constitute a windfall to USWC, and that the investigations
          contemplated at the State and federal level for Universal Service
          Funding will substantially disprove USWC's claims. USWC further
          acknowledges that Focal believes that the costs of implementing the
          Act are costs experienced by all telecommunications carriers and that
          it would be unjust, discriminatory, and anti-competitive to favor USWC
          with additional cost recovery of implementation costs. USWC disagrees
          with these Focal positions.

          In consideration of Focal's willingness to interconnect on the terms
          set forth in this Agreement, and without prejudice to the position it
          may take in the FCC docket or before any state Commission, USWC agrees
          to await the outcome of such proceedings, rather than seek universal
          service support from Focal at this time.

III. DEFINITIONS

          A.   "Act" means the Communications Act of 1934 (47 U.S.C. 151
               et.seq.), as amended by the Telecommunications Act of 1996, and
               as from time to time interpreted in the duly authorized rules and
               regulations of the FCC or a Commission within its state of
               jurisdiction.

          B.   "Access Services" refers to the tariffed interstate and
               intrastate switched access and private line transport services
               offered for the origination and/or termination of interexchange
               traffic (see each Parties' appropriate state and interstate
               access tariffs).

                                     Page 2
<PAGE>
 
          C.   "ADSL" or "Asymmetrical Digital Subscriber Line" means a
               transmission technology which transmits an asymmetrical digital
               signal using one of several transmission methods (for example,
               carrier-less AM/PM discrete multi-tone, or discrete wavelet
               multi-tone).

          D.   "Access Service Request" or "ASR" means the industry standard
               forms and supporting documentation used for ordering Access
               Services. The ASR will be used to order trunking and facilities
               between Focal and USWC for Local Interconnection Service.

          E.   "Automatic Number Identification" or "ANI" means a Feature Group
               D signaling parameter which refers to the number transmitted
               through a network identifying the billing number of the calling
               party.

          F.   "CLASS features" are optional end user switched services that
               include, but are not necessarily limited to: Automatic Call Back;
               Call Trace; Caller ID and Related Blocking Features; Distinctive
               Ringing/Call Waiting; Selective Call Forward; Selective Call
               Rejection. (See Bellcore documentation for definition).

          G.   "BLV/BLVI Traffic" means an operator service call in which the
               caller inquires as to the busy status of or requests an
               interruption of a call on another Customer's Telephone Exchange
               Service line.

          H.   "Central Office Switch" means a switch used to provide
               Telecommunications Services, including, but not limited to:

               a.   "End Office Switches" which are used to terminate Customer
                    station loops for the purpose of interconnecting to each
                    other and to trunks; and

               b.   "Tandem Office Switches" which are used to connect and
                    switch trunk circuits between and among other Central Office
                    Switches. Access tandems provide connections for exchange
                    access and toll traffic while local tandems provide
                    connections for local/EAS traffic.

          I.   "Collocation" means an arrangement whereby one Party's (the
               "Collocating Party") facilities are terminated in its equipment
               necessary for Interconnection or for access to Network Elements
               on an unbundled basis which has been installed and maintained at
               the premises of a second Party (the "Housing Party"). Collocation
               may be "physical" or "virtual". In "Physical Collocation," the
               Collocating Party installs and maintains its own equipment in the
               Housing Party's premises. In "Virtual Collocation," the Housing
               Party installs and maintains the Collocating Party's equipment in
               the Housing Party's premises.

          J.   "Commission" means the Washington Utilities and Transportation
               Commission.

          K.   "Customer" means a third party (residence or business) that
               subscribes to Telecommunications Services provided by either of
               the Parties.

                                     Page 3
<PAGE>
 
          L.   "Calling Party Number" or "CPN" is a Common Channel Signaling
               ("CCS") parameter which refers to the number transmitted through
               a network identifying the calling party.

          M.   "Common Channel Signaling" or "CCS" means a method of digitally
               transmitting call set-up and network control data over a special
               signaling network fully separate from the public voice switched
               network elements that carry the actual call. The CCS used by the
               Parties shall be Signaling System 7.

          N.   "Competitive Local Exchange Carrier" means an entity authorized
               to provide Local Exchange Service that does not otherwise qualify
               as an incumbent LEC.

          0.   "Digital Signal Level" means one of several transmission rates in
               the time division multiplexing hierarchy.

          P.   "Digital Signal Level 0" or "DSO" means the 64 Kbps zero-level
               signal in the time-division multiplex hierarchy.

          Q.   "Digital Signal Level 1" or "DS1" means the 1.544 Mbps
               first-level signal in the time-division multiplex hierarchy. In
               the time-division multiplexing hierarchy of the telephone
               network, DS1 is the initial level of multiplexing.

          R.   "Digital Signal Level 3" or "DS3" means the 44.736 Mbps
               third-level in the time-division multiplex hierarchy. In the
               time-division multiplexing hierarchy of the telephone network,
               DS3 is defined as the third level of multiplexing.

          S.   "Exchange Message Record" or "EMR" is the standard used for
               exchange of telecommunications message information between
               telecommunications providers for billable, non-billable, sample,
               settlement and study data. EMR format is contained in
               BR-O10-200-O10 CRIS Exchange Message Record, a Bellcore document
               that defines industry standards for exchange message records.

          T.   "Fiber-Meet" means an interconnection architecture method whereby
               the Parties physically interconnect their networks via an optical
               fiber interface (as opposed to an electrical interface) at a
               mutually agreed upon location.

          U.   "HDSL" or "High-Bit Rate Digital Subscriber Line" means a
               two-wire or four-wire transmission technology which typically
               transmits a DS1-level signal (or, higher level signals with
               certain technologies), using: 2 Binary / 1 Quartenary ("2B1Q").

          V.   "Integrated Digital Loop Carrier" means a subscriber loop carrier
               system which integrates within the switch at a DS1 level that is
               twenty-four (24) local Loop transmission paths combined into a
               1.544 Mbps digital signal.

          W.   "Interconnection" is as described in the Act and refers to the
               connection of separate pieces of equipment, facilities, or
               platforms between or within networks for the purpose of
               transmission and routing of Telephone Exchange Service traffic
               and Exchange Access traffic.

                                     Page 4
<PAGE>
 
          X.   "Interexchange Carrier" or "IXC" means a carrier that provides,
               directly or indirectly, inter LATA or intra LATA Telephone
               Toll Services.

          Y.   "Integrated Services Digital Network" or "ISDN" means a switched
               network service that provides end-to-end digital connectivity for
               the simultaneous transmission of voice and data. Basic Rate
               Interface-ISDN (BRI-ISDN) provides for a digital transmission of
               two 64 Kbps bearer channels and one 16 Kbps data channel (2B+D).

          Z.   "Local Loop Transmission" or "Loop" means the entire transmission
               path which extends from the network interface or demarcation
               point at a Customer's premises to the Main Distribution Frame or
               other designated frame or panel in a Party's Wire Center which
               serves the Customer.

          AA.  "Main Distribution Frame" or "MDF" means the distribution frame
               of the Party providing the Loop used to interconnect cable pairs
               and line and trunk equipment terminals on a switching system.

          BB.  "Meet-Point Billing" or "MPB" refers to an agreement whereby two
               LECs (including a LEC and CLEC) jointly provide switched access
               service to an Interexchange Carrier, with each LEC (or CLEC)
               receiving an appropriate share of the transport element revenues
               as defined by their effective access tariffs.

          CC.  "MECAB" refers to the Multiple Exchange Carrier Access Billing
               (MECAB) document prepared by the Billing Committee of the
               Ordering and Billing Forum (OBF), that functions under the
               auspices of the Carrier Liaison Committee (CLC) of the Alliance
               for Telecommunications Industry Solutions (ATIS). The MECAB
               document, published by Bellcore as Special Report SR-BDS-000983,
               contains the recommended guidelines for the billing of an access
               service provided by two or more LECs (including a LEC and a
               CLEC), or by one LEC in two or more states within a single LATA.

          DD.  "MECOD" refers to the Multiple Exchange Carriers Ordering and
               Design (MECOD) Guidelines for Access Services - Industry Support
               Interface, a document developed by the Ordering/Provisioning
               Committee under the auspices of the Ordering and Billing Forum
               (OBF), that functions under the auspices of the Carrier Liaison
               Committee (CLC) of the Alliance for Telecommunications Industry
               Solutions (ATIS). The MECOD document, published by Bellcore as
               Special Report SR STS-002643, establishes recommended guidelines
               for processing orders for access service that is to be provided
               by two or more LECs (including a LEC and a CLEC). It is published
               by Bellcore as SRBDS 00983.

          EE.  "Mid-Span Meet" is a point of interconnection between two
               networks, designated by two telecommunications carriers, at which
               one carrier's responsibility for service begins and the other
               carrier's responsibility ends.

                                     Page 5
<PAGE>
 
          FF.  "North American Numbering Plan" or "NANP" means the numbering
               plan used in the United States that also serves Canada, Bermuda,
               Puerto Rico and certain Caribbean Islands. The NANP format is a
               10-digit number that consists of a 3-digit NPA code (commonly
               referred to as the area code), followed by a 3-digit NXX code and
               4-digit line number.

          GG.  "NXX" means the fourth, fifth and sixth digits of a ten-digit
               telephone number.

          HH.  "Point of Interface" or "POI" is a mutually agreed upon point of
               demarcation where the exchange of traffic between two LECs
               (including a LEC and a CLEC) takes place.

          II.  "Party" means either USWC or Focal and "Parties" means USWC and
               Focal.

          JJ.  "Port" means a termination on a Central Office Switch that
               permits customers to send or receive telecommunications services
               over the public switched network, but does not include switch
               features or switching functionality.

          KK.  "Rate Center" means the specific geographic point and
               corresponding geographic area which are associated with one or
               more particular NPA-NXX codes which have been assigned to a LEC
               (or CLEC) for its provision of basic exchange telecommunications
               services. The "rate center point" is the finite geographic point
               identified by a specific V & H coordinate, which is used to
               measure distance-sensitive end user traffic to/from, the
               particular NPA-NXX designations associated with the specific Rate
               Center. The "rate center area" is the exclusive geographic area
               identified as the area within which the LEC (or CLEC) will
               provide Basic Exchange Telecommunications Service bearing the
               particular NPA-NXX designations associated with the specific Rate
               Center. The Rate Center point must be located within the Rate
               Center area.

          LL.  "Reseller" is a category of Local Exchange service provider that
               obtains dial tone and associated telecommunications services from
               another provider through the purchase of bundled finished
               services for resale to its end use customers.

          MM.  Service Control Point" or "SCP" means a signaling end point that
               acts as a database to provide information to another signaling
               end point (i.e., Service Switching Point or another SCP) for
               processing or routing certain types of network calls. A
               query/response mechanism is typically used in communicating with
               an SCP.

          NN.  "Signaling Transfer Point" or "STP" means a signaling point that
               performs message routing functions and provides information for
               the routing of messages between signaling end points. An STP
               transmits, receives and processes Common Channel Signaling
               ("CCS") messages.

          OO.  "Switched Exchange Access Service" means the offering of
               transmission or switching services to Telecommunications Carriers
               for the purpose of the origination or termination of Telephone
               Toll Service. Switched Exchange Access Services include: Feature
               Group A, Feature Group B, Feature Group D,800/888

                                     Page 6
<PAGE>
 
               access, and 900 access and their successors or similar Switched
               Exchange Access services.

          PP   "Traffic Type" is the characterization of intraLATA traffic as
               "local" (local includes EAS), or "toll" which shall be the same
               as the characterization established by the effective tariffs of
               the incumbent local exchange carrier as of the date of this
               agreement.

          QQ.  "Wire Center" denotes a building or space within a building, that
               serves as an aggregation point on a given carrier's network,
               where transmission facilities are connected or switched. Wire
               Center can also denote a building where one or more Central
               Offices, used for the provision of Basic Exchange
               Telecommunications Services and Access Services, are located.
               However, for purposes of Collocation Service, Wire Center shall
               mean those points eligible for such connections as specified in
               the FCC Docket No. 91-141, and rules adopted pursuant thereto.

          RR.  "Routing Point" means a location that a LEC or CLEC has
               designated on its own network as the homing (routing) point for
               traffic, bearing a certain NPA-NXX designation, that is inbound
               to Basic Exchange Telecommunications Services provided by the LEC
               or CLEC. The Routing Point is employed to calculate mileage
               measurements for the distance-sensitive transport element charges
               of Switched Access Services. Pursuant to Bellcore Practice BR
               795-100-100, the Routing Point may be an "End Office" location,
               or a "LEC Consortium Point of Interconnection". Pursuant to that
               same Bellcore Practice, examples of the latter shall be
               designated by a common language location identifier (CLLI) code
               with (x)KD in positions 9, 10, 11, where (x) may be any
               alphanumeric A-Z or 0-9. The above referenced Bellcore document
               refers to the Routing Point as the Rating Point. The Rating
               Point/Routing Point need not be the same as the rate center point
               nor must it be located within the rate center area, but must be
               in the same LATA as the NPA/NXX.(1)


          SS.  "Tariff Services" as used throughout this Agreement refers to the
               applicable Party's interstate tariffs and state tariffs, price
               lists, price schedules and catalogs.

          TT.  "Information Service Traffic" means Local Traffic or IntraLATA
               Toll Traffic which originates on a Telephone Exchange Service
               line and which is addressed to an information service provided
               over a Party's information services platform (e.g., 976).

          UU.  Terms not otherwise defined here, but defined in the Act or in
               regulations implementing the Act, shall have the meaning defined
               there.

- ----------
(1) This sentence is incorporated pursuant to the Arbitrator's decision in
    Docket No. UT-960323.

                                     Page 7
<PAGE>
 
IV.  RATES AND CHARGES GENERALLY

     A.   Prices for termination and transport of traffic, interconnection,
          access to unbundled network elements, and ancillary services are set
          forth in Appendix A.

     B.   USWC's wholesale discounts for resale services are set forth in
          Appendix A.

     C.   The underlying provider of a resold service shall be entitled to
          receive, from the purchaser of switched access, the appropriate access
          charges pursuant to its then effective switched access tariff. For the
          purposes of this paragraph, Unbundled Loops are not considered as
          resold services.

V.   RECIPROCAL TRAFFIC EXCHANGE

     A.   Scope

          Reciprocal traffic exchange addresses the exchange of traffic between
          Focal end users and USWC end users. If such traffic is local, the
          provisions of this Agreement shall apply. Where either party acts as
          an intraLATA toll provider or interLATA Interexchange Carrier (IXC) or
          where either party interconnects and delivers traffic to the other
          from third parties, each party shall bill such third parties the
          appropriate charges pursuant to its respective tariffs or contractual
          offerings for such third party terminations. Absent a separately
          negotiated agreement to the contrary, the Parties will directly
          exchange traffic between their respective networks, without the use of
          third party transit providers.

     B.   Types of Traffic

          The types of traffic to be exchanged under this Agreement include:
          1.   EAS/local traffic as defined above.
          2.   IntraLATA toll traffic as defined above.
          3.   Switched access traffic, or interLATA toll traffic, as
               specifically defined in USWC's state and interstate switched
               access tariffs, and generally identified as that traffic that
               originates at one of the Party's end users and terminates at an
               IXC point of presence, or originates at an IXC point of presence
               and terminates at one of the Party's end users, whether or not
               the traffic transits the other Party's network.
          4.   Transit traffic is any traffic other than switched access, that
               originates from one Telecommunications Carrier's network,
               transits another Telecommunications Carrier's network, and
               terminates to yet another Telecommunications Carrier's network.

               Transit service provides the ability for a Telecommunications
               Carrier to use its connection to a local or access tandem for
               delivery of calls that

                                     Page 8
<PAGE>
 
               originate with a Telecommunications Carrier and terminate to a
               company other than the tandem company, such as another
               Competitive Local Exchange Carrier, an existing Exchange Carrier,
               or a wireless carrier. In these cases, neither the originating
               nor terminating end user is a customer of the tandem
               Telecommunications Carrier. The tandem Telecommunications Carrier
               will accept traffic originated by a Party and will terminate it
               at a point of interconnection with another local, intraLATA or
               interLATA network Telecommunications Carrier. This service is
               provided through local and access tandem switches.

          5.   Ancillary traffic includes all traffic destined for ancillary
               services, or that may have special billing requirements,
               including, but not limited to the following:

               a.   Directory Assistance
               b.   911/E911
               c.   Operator call termination (busy line interrupt and verify)
               d.   800/888 database dip
               e.   LIDB
               f.   Information services requiring special billing.

          6.   Unless otherwise stated in this Agreement, ancillary traffic will
               be exchanged in accordance with whether the traffic is Local/EAS,
               intraLATA toll, or Switched Access.

     C.   Types of Exchanged Traffic

          1.   Termination of Local Traffic.

               Local traffic will be terminated as Local Interconnection Service
               (LIS).

          2.   Transport of Local Traffic

               As negotiated between the Parties, the exchange of local traffic
               between the Parties may occur in several ways:

               a.   While the parties anticipate the use of two way trunks for
                    the delivery of local traffic, either Party may elect to
                    provision its own one-way trunks for delivery of local
                    traffic to be terminated on the other Party's network at the
                    "initial" point of interconnection.

               b.   The Parties may elect to purchase transport services from
                    each other or from a third party. Such transport delivers
                    the originating Party's local traffic to the terminating
                    Party's end office or tandem for call termination. Transport
                    may be purchased as either tandem switched transport (which
                    is included in the tandem call termination rate) or direct
                    trunk transport.

                                     Page 9
<PAGE>
 
               c.   Based on forecasted traffic at Focal's busy hour in CCS,
                    where there is a DS1's worth of traffic (512 CCS) between
                    the Focal switch and a USWC end office, the Parties agree to
                    provision a dedicated (i.e., direct) two-way trunk group
                    from the Focal switch directly to the USWC end office. To
                    the extent that Focal has established a collocation
                    arrangement at a USWC end office location, and has available
                    capacity, the Parties agree that Focal shall provide two-way
                    direct trunk facilities, when required, from that end office
                    to the Focal switch. In all other cases, the direct facility
                    may be provisioned by USWC or Focal or a third party. If
                    both Focal and USWC desire to provision the facility and
                    cannot otherwise agree, the parties may agree to resolve the
                    dispute through the submission of competitive bids.

          3.   Transit Traffic.

               a.   USWC will accept traffic originated by Focal and will
                    terminate it at a point of interconnection with another
                    CLEC, Exchange Carrier, Interexchange Carrier or Wireless
                    Carrier. USWC will provide this transit service through
                    local and access tandem switches. Focal may also provide
                    USWC with transit service.

               b.   The Parties expect that all networks involved in
                    transporting transit traffic will deliver calls to each
                    involved network with CCS/SS7 protocol and the appropriate
                    ISUP/TCAP message to facilitate full interoperability and
                    billing functions. In all cases, the originating company is
                    responsible to follow the EMR standard and to exchange
                    records with both the transiting company and the terminating
                    company, to facilitate the billing process to the
                    originating network.

               c.   The Parties will use industry standards developed to handle
                    the provision and billing of Switched Access by multiple
                    providers (MECAB, MECOD and the Parties' FCC tariffs),
                    including the onetime provision of notification to Focal of
                    the billing name, billing address and carrier identification
                    codes of all interexchange carriers originating or
                    terminating at each USWC access tandem.

          4.   Toll Traffic.

               Toll traffic routed to an access tandem, or directly routed to an
               end office, will be terminated as Switched Access Service.
               Traffic terminated at the access tandem will be routed to the end
               offices within the LATA that subtend the USWC access tandem
               switch. Switched Access Service also allows for termination at an
               end office or tandem via direct trunked circuits provisioned
               either by USWC or Focal.

                                    Page 10
<PAGE>
 
     D.   Rate Structure -- Local Traffic

          1.   Call Termination

               a.   The Parties agree that call termination rates as described
                    in Appendix A will apply reciprocally for the termination of
                    local/EAS traffic per minute of use.

               b.   For traffic terminated at an USWC or Focal end office, the
                    end office call termination rate in Appendix A shall apply.

               c.   For traffic terminated at a USWC or Focal tandem switch,
                    tandem call termination rate in Appendix A shall apply. The
                    tandem call termination rate provides for end office call
                    termination, tandem switched transport and tandem switching.

                    The Parties acknowledge that Focal will initially serve all
                    of its customers within a given LATA through a single Focal
                    switch. The Parties also acknowledge that Focal may, in the
                    future, deploy additional switches in each LATA. (2)

               d.   For purposes of call termination, the initial Focal switch
                    shall be treated as a tandem switch. (3)

               e.   Pursuant to the Arbitrator's decision in
                    Docket No. UT-0960323, USWC's proposed paragraph has been
                    deleted.

          2.   Transport
          a.        If the Parties elect to each provision their own one-way
                    trunks to the other Party's end office for the termination
                    of local traffic, each

- --------------
(2) This sentence is included pursuant to the Arbitrator's decision in Docket
    No. UT-960323.

(3) This sentence is included pursuant to the Arbitrator's decision in Docket
    No. UT-960323.

                                    Page 11
<PAGE>
 
                    Party will be responsible for its own expenses associated
                    with the trunks and no transport charges will apply. Call
                    termination charges shall apply as described above.

          b.        If one Party desires to purchase direct trunk transport from
                    the other Party, the following rate elements will apply.
                    Transport rate elements include the direct trunk transport
                    facilities between the POI and the terminating party's
                    tandem or end office switches.. The applicable rates are
                    described in Appendix A.

          c.        Direct-trunked transport facilities are provided as
                    dedicated DS3 or DS1 facilities without the tandem switching
                    functions, for the use of either Party between the point of
                    interconnection and the terminating end office or tandem
                    switch.

          d.        If the Parties elect to establish two-way direct trunks, the
                    compensation for such jointly used 'shared' facilities shall
                    be adjusted as follows. The nominal compensation shall be
                    pursuant to the rates for direct trunk transport in Appendix
                    A. The actual rate paid to the provider of the direct trunk
                    facility shall be reduced to reflect the provider's use of
                    that facility. The adjustment in the direct trunk transport
                    rate shall be a percentage that reflects the provider's
                    relative use (i.e., originating minutes of use) of the
                    facility in the busy hour.

          e.        Multiplexing options are available at rates described in
                    Appendix A.

     E.   Rate Structure -- Toll Traffic.

          Applicable Switched Access Tariff rates, terms, and conditions apply
          to toll traffic routed to an access tandem, or directly to an end
          office. Relevant rate elements include Direct Trunk Transport (DTT) or
          Tandem Switched Transport (TST), Interconnection Charge (IC), Local
          Switching, and Carrier Common Line, as appropriate.

     F.   Rate Structure --Transit Traffic.

          Applicable switched access, Type 2 or LIS transport rates apply for
          the use of USWC's network to transport transit traffic. For transiting
          local traffic, the applicable local transit rate applies to the
          originating party per Appendix A. For transiting toll traffic, the
          Parties will charge the applicable switched access rates to the
          responsible carrier. For terminating transiting wireless traffic, the
          Parties will charge their applicable rates to the wireless provider.
          For transiting wireless traffic, the parties will charge each other
          the applicable local transit rate.

     G.   LIS Interface Code Availability And Optional Features

          1.   Interface Code Availability.


                                    Page 12
<PAGE>
 
          Supervisory Signaling specifications, and the applicable network
          channel interface codes for LIS trunks, are the same as those used for
          Feature Group D Switched Access Service, as described in the Parties'
          applicable switched access tariffs.

     2.   Optional Features.

          a.   Inband MF or SS7 Out of Band Signaling.

               Inband MF signaling and SS7 Out of Band Signaling are available
               for LIS trunks. MF signaling or SS7 Out-of-Band Signaling must be
               requested on the order for the new LIS trunks. Provisioning of
               the LIS trunks equipped with MF signaling or SS7 Out of Band
               Signaling is the same as that used for Feature Group D Switched
               Access. Common Channel Signaling Access Capability Service, as
               set forth in Section XXVIII herein, must be ordered by Focal when
               SS7 Out-of-Band Signaling is requested on LIS trunks.

          b.   Clear Channel Capability.

               Clear Channel Capability permits 24 DSO-64 kbit/s services or
               1.536 Mbit/s of information on the 1.544 Mbit/s line rate. Clear
               Channel Capability is available for LIS trunks equipped with SS7
               Out-of-Band Signaling. Clear Channel Capability is only available
               on trunks to USWC's access tandem switch or USWC's end office
               switches (where available); (Clear Channel Capability is not
               available on trunks to USWC's local tandem switches or end
               offices where it is currently not deployed. Focal agrees to use
               the Network Interconnection and Unbundled Element Request process
               to request clear channel capability for such additional switches.
               Prices for such additional clear channel capability, if any, will
               be established through the NIUER Process). Clear Channel
               Capability must be requested on the order for the new LIS trunks.
               The provisioning of the LIS trunks equipped with Clear Channel
               Capability is the same as that used for Feature Group D Switched
               Access Service. USWC will provide Focal with a listing of USWC
               end offices, local tandems and access tandems equipped with clear
               channel capability.

     H.   Measuring Local Interconnection Minutes

          1.   Measurement of terminating Local Interconnection Minutes begins
               when the terminating LIS entry switch receives answer supervision
               from the called end user's end office indicating the called end
               user has answered. The measurement of terminating call usage over
               LIS trunks ends when the terminating LIS entry switch receives
               disconnect supervision from either the called end user's end
               office, indicating the called end user has

                                    Page 13
<PAGE>
 
               disconnected, or Focal's point of interconnection, whichever is
               recognized first by the entry switch.

          2.   USWC and Focal are required to provide each other the proper call
               information (e.g., originated call party number and destination
               call party number, etc.) to enable each Party to issue bills in a
               complete and timely fashion.

I.   Testing

     1.   Acceptance Testing

          At the time of installation of an LIS trunk group, and at no
          additional charge, the Parties will cooperatively test the same
          parameters tested for terminating Feature Group D Switched Access
          Service. Please see USWC's applicable switched access tariff for the
          specifications.

     2.   Testing Capabilities

          a.   Terminating LIS testing is provided where equipment is available,
               with the following test lines: seven-digit access to balance (100
               type), milliwatt (102 type), nonsynchronous or synchronous,
               automatic transmission measuring (105 type), data transmission
               (107 type), loop-around, short circuit, open circuit, and
               non-inverting digital loopback (108 type).

          b.   In addition to LIS acceptance testing, other tests are available
               (e.g., additional cooperative acceptance testing, automatic
               scheduled testing, cooperative scheduled testing, manual
               scheduled testing, and non-scheduled testing) at the applicable
               tariff rates.

J.   Ordering

     1.   When ordering LIS, the ordering Party shall specify on the service
          order: 1) the type and number of interconnection facilities to
          terminate at the point of interconnection in the serving wire center;
          2) the type of interoffice transport, (i.e., direct trunk transport or
          tandem switched transport); 3) the peak busy hour CCS from the Focal
          end office; 4) the number of trunks to be provisioned at a local
          exchange office or tandem; 5) and any optional features (see form
          Appendix B). When the ordering Party requests facilities, routing, or
          optional features different than those determined to be available, the
          Parties will work cooperatively in determining an acceptable
          configuration, based on available facilities, equipment and routing
          plans.

     2.   When the ordering Party initially orders a DS3 interconnection
          facility, in conjunction with tandem switched transport to a tandem,
          or DS3 direct trunk transport facilities to a tandem or local exchange
          office, the provider

                                    Page 14
<PAGE>
 
          will forward the appropriate DS1 facility record information necessary
          to identify the circuit facility assignment (CFA). On subsequent
          orders utilizing existing DS3 interconnection facilities, or the DS3
          trunk transport facility, the provider will assign the DS1 facility to
          the DS3 interconnection facility or DS3 direct trunk transport
          facility, as directed by the ordering Party.

     3.   A joint planning meeting will precede Focal and USWC trunking orders.
          These meetings will result in the transmittal of Access service
          Requests (ASRs) to initiate order activity. A Party requesting tandem
          interconnection will provide its best estimate of the traffic
          distribution to each end office subtending the tandem.

     4.   Service intervals and due dates or negotiated arrangements will be
          determined on an individual case basis.

K.   Billing Arrangements

     1.   USWC and Focal desire to submit separate bills, pursuant to their
          separate tariffs, to interchange carriers for their respective
          portions of jointly provided switched access service.

          Based on the negotiated POI, the Parties will agree on a meet point
          percentage to enable the joint provisioning and billing of Switched
          Access Services to third parties in conformance with the Meet-Point
          Billing guidelines adopted by and contained in the Ordering and
          Billing Forum's MECAB and MECOD documents and referenced in USWC's
          Switched Access Tariffs. The Parties understand and agree that MPB
          arrangements are available and functional only to/from Interchange
          Carriers who directly connect with the tandem(s) that Focal sub-tends
          in each LATA.

     2.   The parties will use reasonable efforts, individually and
          collectively, to maintain provisions in their respective federal and
          state access tariffs, and/or provisions within the National Exchange
          Carrier Association ("NECA") Tariff No. 4, or any successor tariff,
          sufficient to reflect this MPB arrangement, including MPB percentages.

     3.   As detailed in the MECAB document, Focal and USWC will exchange all
          information necessary to bill third parties for Switched Access
          Services traffic jointly handled by Focal and USWC via the meet point
          arrangement in a timely fashion. Information shall be exchanged in
          Exchange message Record ("EMR") format (Bellcore Standard BR
          010-200-010, as amended) on magnetic tape or via a mutually acceptable
          electronic file transfer protocol. The Parties will exchange records
          pursuant to this paragraph without additional compensation.

     4.   The Parties will agree upon reasonable audit standards and other
          procedures as required to ensure billing accuracy.

                                    Page 15
<PAGE>
 
     5.   Each company will bill the IXC's the appropriate rate elements in
          accordance with their respective interstate and intrastate tariffs, as
          follows:

          Rate Element                                 Billing Company
          ------------                                 ---------------
          Carrier Common Line                          Dial Tone Provider
          Local Switching                              Dial Tone Provider
          Interconnection Charge                       Dial Tone Provider
          Local Transport Termination                  Based on negotiated BIP
          Local Transport Facility                     Based on negotiated BIP
               (also called Tandem
               Transmission per mile)
          Tandem Switching                             Access Tandem Provider
          Entrance Facility                            Access Tandem Provider

     6.   For originating 800/888 traffic routed to an access tandem, the tandem
          provider will perform 800/888 database inquiry and translation
          functions and bill the inquiry charge and translation charge (if any)
          to the interexehange carrier pursuant to tariff.

     7.   Pursuant to the Arbitrator's decision in Docket No. UT-960323, this
          proposed paragraph has been deleted.

L.   Mileage Measurement

     Where required, the mileage measurement for LIS facilities and trunks is
     determined in the same manner as the mileage measurement for Feature Group
     D Switched Access Service.

M.   Construction Charges

     For issues related to construction charges, see Section XXIX of this
     Agreement.

VI.  INTERCONNECTION

     A.   Definition
          1.   "Interconnection" is the linking of the USWC and Focal networks
               for the mutual exchange of traffic and for Focal access to
               unbundled network elements. Interconnection does not include the
               transport and termination of traffic. interconnection is provided
               by Virtual or physical collocation, entrance facilities or meet
               point arrangements.

          2.   USWC will provide interconnection at the line side of the local
               switch, the trunk side of the local switch, trunk interconnection
               points of the tandem switch, central office cross-connect points,
               and signaling transfer points necessary to exchange traffic and
               access call related databases.

     B.   Mid-span Meet POI

                                    Page 16
<PAGE>
 
          1.   A Mid-Span Meet POI is a negotiated point of interface, limited
               to the interconnection of facilities between one Party's switch
               and the other Party's switch. The actual physical point of
               interface and facilities used will be subject to negotiations
               between the Parties. Each Party will be responsible for its
               portion of the build to the Mid-Span Meet POI, if the meet point
               arrangement is used exclusively for the exchange of local
               traffic.

          2.   If the Mid-Span Meet arrangement is to be used for access to
               unbundled network elements, Focal must pay the portion of the
               economic costs of the Mid-Span Meet arrangement used by Focal for
               access to unbundled network elements.

     C.   Collocation

          Interconnection may be accomplished through either virtual or physical
          collocation. The terms and conditions under which collocation will be
          available are described in Section VII herein.

     D.   Entrance Facility

          Interconnection may be accomplished through the provision of an
          entrance facility. An entrance facility extends from the serving wire
          center of the provider to the other party's switch location. Entrance
          facilities may not extend beyond the area described by the provider's
          serving wire center. The rates for entrance facilities are provided in
          Appendix A.

     E.   Quality of Interconnection
          USWC will not, for the purpose of interconnection, provide to Focal
          less favorable terms and conditions than USWC provides itself or in a
          manner less efficient than it would impose on itself. The quality of
          interconnection will be at least equal to that of USWC. To the extent
          that Focal requests higher or lower quality interconnection, Focal
          agrees to use the New Interconnection/Unbundled Element Request
          procedure described in Section XXIII.

          Both Parties agree to manage their network switches in accordance with
          the Bellcore LSSGR. The acceptable service levels for LIS and the
          criteria for applying protective controls will be administered in the
          same manner as the network management for Switched Access Service.

     F.   Points of Interface (POI)

          Upon the request for specific point to point routing, USWC will make
          available to Focal information indicating the location and technical
          characteristics of USWC's network facilities. The following
          alternatives are negotiable: (1) a DS1 or DS3 entrance facility, where
          facilities are available (where facilities are not available and USWC
          is required to build, see Section XXIX for issues relating to
          construction charges). (2) Virtual Collocation; (3) Physical
          Collocation;

                                    Page 17
<PAGE>
 
          and (4) negotiated Mid-Span Meet facilities. Each Party is responsible
          for providing its own facilities up to the Mid-Span Meet POI. The
          Parties will negotiate the facilities arrangement between their
          networks.

     G.   Trunking Requirements

          1.   USWC agrees to provide designed interconnection facilities that
               meet the same technical criteria and service standards, such as
               probability of blocking in peak hours and transmission standards,
               in accordance with industry standards.

          2.   Two-way trunk groups will be established wherever possible.
               Exceptions to this provision will be based on billing, signaling,
               and network requirements. For example, (1) billing requirements -
               switched access vs. local traffic, (2) signaling requirements -
               MF vs. SS7, and (3) network requirements - directory assistance
               traffic to TOPS tandems. The following is the current list of
               traffic types that require separate trunk groups, unless
               specifically otherwise agreed to by the Parties (deleted)stated
               in this agreement(deleted). The following list does not include
               separate trunks for transit traffic to third parties. The Parties
               agree that if recording and reporting procedures cannot be
               implemented to appropriately measure local and toll transit
               traffic, either Party may request separate transit trunks. In
               such a case, the other Party will not unreasonably withhold its
               consent to establish separate trunks.(4)

               a.        IntraLATA toll and switched access trunks
               b.        EAS/local trunks
               c.        Directory Assistance trunks
               d.        911/E911 trunks
               e.        Operator services trunks
               f.        Commercial Mobile Radio Service/Wireless traffic for
                         which Focal serves as the transit provider between the
                         CMRS provider and USWC.
               g.        (deleted) Non USWC toll (deleted)
               h.        (deleted) Non USWC local(deleted)
               I.        Meet Point Billing Trunks (for the joint provision of
                         switched access).

          3.   Trunk group connections will be made at a DS1 or multiple DS1
               level for exchange of EAS/local, intraLATA toll,
               wireless/Commercial Mobile Radio Service, and switched access
               traffic. Ancillary service trunk groups will be made below a DS1
               level, as negotiated.

          4.   The Parties will provide Common Channel Signaling (CCS) to one
               another, where available, in conjunction with all Local/EAS Trunk
               Circuits.

- ---------
(4) The Parties have amended this provision in lieu of the disputed separate
    trunk groups for local and toll transit traffic (formerly g. and h. below).


                                    Page 18
<PAGE>
 
               All CCS signaling parameters will be provided including
               calling party number (CPN), originating line information (OLI)
               calling party category, charge number, etc. All privacy
               indicators will be honored.

          5.   Where CCS is not available, in-band multi-frequency (MF) wink
               start signaling will be provided. When the Parties interconnect
               via CCS for jointly provided switched access service, the tandem
               provider will provide MF/CCS interworking as required for
               interconnection with interexchange carriers who use MF signaling.

          6.   The Parties will follow all Ordering and Billing Forum adopted
               standards pertaining to CIC/OZZ codes.

          7.   USWC will cooperate in the provision of TNS (Transit Network
               Selection) for the joint provision of switched access.

          8.   The Parties shall terminate local/EAS traffic exclusively on
               local/EAS trunk groups. No local/EAS trunk groups shall be
               terminated on USWC's access tandems.

     H.   Service Interruptions

          1.   Standards and procedures for notification of trunk disconnects
               will be jointly developed by the Parties. Neither Party shall be
               expected to maintain active status for a trunk disconnected by
               the other Party for an extended or indefinite period of time.
               Collectively, the Parties will use their best good faith efforts
               to complete and agree on such plan.

          2.   The characteristics and methods of operation of any circuits,
               facilities or equipment of either Party connected with the
               services, facilities or equipment of the other Party pursuant to
               this Agreement shall not: 1) interfere with or impair service
               over any facilities of the other Party; its affiliated companies,
               or its connecting and concurring carriers involved in its
               services; 2) cause damage to their plant; 3) violate any
               applicable law or regulation regarding the invasion of privacy of
               any communications carried over the Party's facilities; or 4)
               create hazards to the employees of either Party or to the public.
               Each of these requirements is hereinafter referred to as an
               "Impairment of Service".

          3.   If either Party causes an Impairment of Service, as set forth in
               this Section, the Party whose network or service is being
               impaired (the "Impaired Party") shall promptly notify the Party
               causing the Impairment of Service (the "Impairing Party") of the
               nature and location of the problem. They shall advise the
               Impairing Party that, unless promptly rectified, a temporary
               discontinuance of the use of any circuit, facility or equipment
               may be required. The Impairing Party and the Impaired Party agree
               to work together to attempt to promptly resolve the Impairment of
               Service. If the Impairing Party is unable to promptly remedy the

                                    Page 19
<PAGE>
 
               Impairment of Service, the Impaired Party may temporarily
               discontinue use of the affected circuit, facility or equipment.

          4.   Each Party shall be solely responsible, and bear the expense, for
               the overall design of its services. Each Party shall also be
               responsible for any redesign or rearrangement of its services
               that may be required because of changes in facilities, operations
               or procedures, minimum network protection criteria, and operating
               or maintenance characteristics of the facilities.

          5.   To facilitate trouble reporting and to coordinate the repair of
               the service provided by each Party to the other under this
               Agreement, each Party shall designate a Trouble Reporting Control
               Office (TRCO) for such service.

          6.   Where new facilities, services and arrangements are installed,
               the TRCO shall ensure that continuity exists and take appropriate
               transmission measurements before advising the other Party that
               the new circuit is ready for service.

          7.   Each Party shall furnish a trouble reporting telephone number for
               the designated TRCO. This number shall give access to the
               location where facility records are normally located and where
               current status reports on any trouble reports that are readily
               available. Alternative out-of-hours procedures shall be
               established to ensure access to a location that is staffed and
               has the authority to initiate corrective action.

          8.   Before either Party reports a trouble condition, they shall use
               their best efforts to isolate the trouble to the other's
               facilities.

               a.   In cases where a trouble condition affects a significant
                    portion of the other's service, the Parties shall assign the
                    same priority provided to other interconnecting carriers.

               b.   The Parties shall cooperate in isolating trouble conditions.

     I.   Interconnection Forecasting

          1.   The Parties agree that during the first year of interconnection,
               joint forecasting and planning meetings will take place no less
               frequently than once per quarter.

          2.   The Parties shall establish joint forecasting responsibilities
               for traffic utilization over trunk groups. Intercompany forecast
               information must be provided by the Parties to each other four
               times a year. The quarterly forecasts shall include forecasted
               requirements for each trunk group identified in Paragraph G(2) of
               this Section. In addition, the forecast shall include, for 
               tandem-switched traffic, the quantity of tandem-switched traffic
               forecasted for each subtending end office. The Parties recognize

                                    Page 20
<PAGE>
 
               that, to the extent historical traffic data can be shared between
               the Parties, the accuracy of the forecasts will improve.
               Forecasts shall be for a minimum of three (current and plus-1 and
               plus-2) years;

               a.   The use of Common Language Location Identifier (CLLI-MSG),
                    which are described in Bellcore documents BR 795-100-100 and
                    BR 795-400-100;

               b.   A description of major network projects anticipated for the
                    following six months that could affect the other Party.
                    Major network projects include trunking or network
                    rearrangements, shifts in anticipated traffic patterns, or
                    other activities that are reflected by a significant
                    increase or decrease in trunking demand for the following
                    forecasting period. This planning will include the issues of
                    network capacity, forecasting and compensation calculation,
                    where appropriate.

          3.   If differences in quarterly forecasts of the Parties vary by more
               than 24 additional DSO two-way trunks for each Local
               Interconnection Trunk Group, the Parties shall meet to reconcile
               the forecast to within 24 DSO trunks.

          4.   If a trunk group is under 75 percent of centum call seconds (ccs)
               capacity on a monthly average basis for each month of any three
               month period, either Party may request to resize the trunk group,
               which resizing will not be unreasonably withheld. If a resizing
               occurs, the trunk group shall not be left with less than 25
               percent excess capacity. In all cases, grade of service
               objectives identified below shall be maintained.

          5.   Each Party shall provide a specified point of contact for
               planning, forecasting and trunk servicing purposes.

VII. COLLOCATION
     A.   General Provisions

          1.   Collocation allows Focal to obtain dedicated space in a USWC wire
               center and to place equipment in such spaces to interconnect with
               the USWC network. Focal may request collocation at other USWC
               locations pursuant to the NIUER Process or through additional
               interconnection negotiations under the Act. USWC will provide the
               resources necessary for the operation and economical use of
               collocated equipment. POIs for network interconnection can be
               established through virtual or physical collocation arrangements.

          2.   Collocation is offered for network interconnection between the
               Parties. The collocated party may cross connect to other
               collocated parties via expanded interconnection channel
               terminations provided by USWC,

                                    Page 21
<PAGE>
 
               provided that Focal's collocated equipment is used for
               interconnection with USWC or access to USWC's unbundled network
               elements. Additional terms, conditions and rates apply in
               conjunction with subsequent call termination (e.g., call
               termination charges, tandem switching, tandem-switched transport,
               see Section V, Reciprocal Traffic Exchange.)

          3.   Except when Focal purchases USWC's unbundled network transmission
               elements, Focal will construct its own fiber optic cable to the
               USWC designated point of interconnection. USWC will extend
               Focal's fiber optic cable from the POI to the cable vault within
               the wire center. If necessary, USWC may bring the cable into
               compliance with USWC internal fire code standards and extend the
               cable to the collocated space.

          4.   Focal will be provided two points of entry into the USWC wire
               center only when there are at least two existing entry points for
               USWC cable and when there are vacant entrance ducts in both. USWC
               will promptly remove any unused cabling to free up entrance ducts
               when no other ducts are available. Cable entry will be limited to
               fiber facilities.

          5.   Focal. may collocate transmission equipment to terminate basic
               transmission facilities. Focal may request collocation of other
               equipment pursuant to the NIUER Process or through additional
               interconnection negotiations under the Act. CLEC must identify
               what equipment will be installed, to allow for USWC to use this
               information in engineering the power, floor loading, heat
               release, environmental particulant level, and HVAC.

          6.   Nothing in this part shall be construed to limit Focal's ability
               to obtain both virtual and physical collocation in a single
               location.

     B.   Virtual Collocation

          1.   USWC shall provide virtual collocation for the purpose of
               Interconnection or access to unbundled Network Elements subject
               to the rates, terms and conditions of this Agreement.

          2.   Focal will not have physical access to the USWC wire center
               building pursuant to a virtual collocation arrangement.

          3.   Focal will be responsible for obtaining and providing to USWC
               administrative codes, e.g., common language codes, for all
               equipment specified by Focal and installed in wire center
               buildings.

          4.   Focal will be responsible for payment of training of USWC
               employees for the maintenance, operation and installation of
               Focal's virtually collocated equipment when that equipment is
               different than the equipment used by USWC.

                                    Page 22
<PAGE>
 
          5.   Focal will be responsible for payment of charges incurred in the
               maintenance and/or repair of Focal's virtually collocated
               equipment.

          6.   USWC does not guarantee the reliability Focal's virtually
               collocated equipment.

          7.   Focal is responsible for ensuring the functionality of virtually
               collocated SONET equipment provided by different manufacturers.

          8.   Maintenance Labor, Inspector Labor, Engineering Labor and
               Equipment Labor business hours are considered to be Monday
               through Friday, 8:00am to 5:00pm and after business hours are
               after 5:00pm and before 8:00am, Monday through Friday, all day
               Saturday, Sunday and holidays.

          9.   Focal will transfer possession of Focal's virtually collocated
               equipment to USWC via a no cost lease. The sole purpose of the
               lease is to provide USWC with exclusive possessory rights to
               Focal's virtually collocated equipment. Title to the Focal
               virtually collocated equipment shall not pass to USWC.

          10.  Installation and maintenance of Focal's virtually collocated
               equipment will be performed by USWC or a USWC authorized vendor.

          11.  Focal shall ensure that upon receipt of the Focal virtually
               collocated equipment by USWC, all warranties and access to
               ongoing technical support are passed through to USWC, all at
               Focal's expense. The interconnector shall advise the manufacturer
               and seller of the virtually collocated equipment that it will be
               possessed, installed and maintained by USWC.

          12.  Focal's virtually collocated equipment must comply with the
               Bellcore Network Equipment Building System (NEBS) Generic
               Equipment Requirements TR-NWT-000063, Company wire center
               environmental and transmission standards and any statutory
               (local, state or federal) and/or regulatory requirements in
               effect at the time of equipment installation or that subsequently
               become effective. Focal shall provide USWC interface
               specifications (e.g., electrical, functional, physical and
               software) of Focal's virtually collocated equipment.

          13.  USWC may restrict the type of virtually collocated equipment.
               USWC will only permit basic transmission terminating equipment to
               be virtually collocated by Focal. Focal may request collocation
               of other equipment pursuant to the NIUER Process or through
               additional interconnection negotiations under the Act.

          14.  Focal must specify all software options and associated plug-ins
               for its virtually collocated equipment.


                                    Page 23
<PAGE>
 
          15.  Focal is responsible for purchasing and maintaining a supply of
               spares. Upon failure of Focal's virtually collocated equipment,
               Focal is responsible for transportation and delivery of
               maintenance spares to USWC at the wire center housing the failed
               equipment.

     C.   Physical Collocation

          1.   USWC shall provide to Focal Physical Collocation of equipment
               necessary for Interconnection or for access to unbundled Network
               Elements, except that USWC may provide for Virtual collocation if
               USWC demonstrates to the Commission that Physical Collocation is
               not practical for technical reasons or because of space
               limitations, as provided in Section 251(c)(6) of the Act. USWC
               shall provide such Collocation for the purpose of Interconnection
               or access to unbundled Network Elements, except as otherwise
               mutually agreed to in writing by the Parties or as required by
               the FCC or the appropriate Commission subject to the rates, terms
               and conditions of this Agreement.

          2.   Where Focal is Virtually Collocated in a premises which was
               initially prepared for Virtual Collocation, Focal may elect to
               (i) retain its Virtual Collocation in that premises and expand
               that Virtual Collocation according to the rates, terms and
               conditions of this Agreement, or (ii) unless it is not practical
               for technical reasons or because of space limitations, convert
               its Virtual Collocation at such premises to Physical Collocation,
               in which case Focal shall coordinate the construction and
               rearrangement with USWC of its equipment (IDLC and transmission)
               and circuits for which Focal shall pay USWC at applicable rates,
               and pursuant to the other terms and conditions in this Agreement.
               In addition, all applicable Physical Collocation recurring
               charges shall apply.

          3.   Focal will be allowed access to the POI on non-discriminatory
               terms. Focal owns and is responsible for the installation,
               maintenance and repair of its transmission equipment located
               within the space rented from USWC.

          4.   Focal must use leased space promptly and may not warehouse space
               for later use or sublease to another provider. Physical
               collocation is offered in wire centers on a space-available,
               first come, first-served basis.

          5.   The minimum standard leasable amount of floor space is 100 square
               feet. Focal must efficiently use the leased space; no more than
               50% of the floor space may be used for storage cabinets and work
               surfaces. The Commission will be the final arbitrator in points
               of dispute between the parties.

          6.   Focal's leased floor space will be separated from other
               competitive providers and USWC space through cages or hard walls.
               Focal may elect to have USWC construct the cage, or choose from
               USWC approved

                                    Page 24
<PAGE>
 
               contractors to construct the cage, meeting USWC's installation
               Technical Publication 77350.

          7.   The following standard features will be provided by USWC:

               a.   Heating, ventilation and air conditioning.

               b.   Smoke/fire detection and any other building code
                    requirement.

          8.   USWC Responsibilities.

               a.   Design the floor space within each wire center which will
                    constitute CLEC's leased space.

               b.   Ensure that the necessary construction work is performed to
                    build CLEC's leased physical space and the riser from the
                    vault to the leased physical space.

               c.   Develop a quotation specific to Focal's request.

               d.   Extend USWC-provided and owned fiber optic cable from the
                    POI through the cable vault and extending the cable to
                    Focal's leased physical space or place the cable in fire
                    retardant tubing prior to extension to Focal's leased
                    physical space.

               e.   Installation and maintenance and all related activity
                    necessary to provide Channel Termination between USWC's and
                    Focal's equipment.

               f.   Work cooperatively with Focal in matters of joint testing
                    and maintenance.

          9.   Focal Responsibilities

               a.   Determine the type of enclosure for the physical space.

               b.   Where applicable, procure, install and maintain all fiber
                    optic facilities up to the USWC designated POI.

               c.   Install, maintain, repair and service all Focal's equipment
                    located in the leased physical space.

               d.   Ensure that all equipment installed by Focal complies with
                    Bellcore Network Equipment Building System Generic Equipment
                    requirements, USWC wire center environmental and
                    transmission standards, and any statutory (local, federal,
                    or state) or regulatory requirements in effect at the time
                    of equipment installation or that subsequently become
                    effective.

                                    Page 25
<PAGE>
 
          10.  Once construction is complete for physical collocation and Focal
               has accepted its leased physical space, Focal may order its DSO,
               DS1, DS3 or other Expanded Interconnection Channel Terminations.

          11.  Focal may not extend dark fiber to Focal's leased physical space
               or connecting DS1/DS3 Channel Terminations to USWC dark fiber.

          12.  If, at any time, USWC determines that the equipment or the
               installation does not meet requirements, Focal will be
               responsible for the costs associated with the removal,
               modification to, or installation of the equipment to bring it
               into compliance. If Focal fails to correct any noncompliance
               within fifteen (15) days of written notice of non-compliance,
               USWC may have the equipment removed or the condition corrected at
               Focal's expense.

          13.  If, during installation, USWC determines Focal activities or
               equipment are unsafe, non-standard or in violation of any
               applicable laws or regulations, USWC has the right to stop work
               until the situation is remedied. If such conditions pose an
               immediate threat to the safety of USWC employees, interfere with
               the performance of USWC's service obligations, or pose an
               immediate threat to the physical integrity of the conduit system
               or the cable facilities, USWC may perform such work and/or take
               action as is necessary to correct the condition at Focal's
               expense.

          14.  For each Physical Collocation, the Parties agree to execute an
               individual 'Physical Collocation Agreement' in form attached
               hereto as Appendix C.

     D.   Collocation Rate Elements

          1.   Common Rate Elements

               The following rate elements are common to both virtual and
               physical collocation:

               a.   Quote Preparation Fee. This covers the work involved in
                    developing a quotation for Focal for the total costs
                    involved in its collocation request.

               b.   Entrance Facility. Provides for fiber optic cable on a per
                    fiber basis from the point of interconnection utilizing USWC
                    owned, conventional single mode type of fiber optic cable to
                    the collocated equipment (for virtual collocation) or to the
                    leased space (for physical collocation). Entrance facility
                    includes riser, fiber placement, entrance closure,
                    conduit/innerduct, and core drilling.

               c.   Cable Splicing. Represents the labor and equipment to
                    perform a subsequent splice to the Focal provided fiber
                    optic cable after the

                                    Page 26
<PAGE>
 
                    initial installation splice. Includes a per-setup and a
                    per-fiber-spliced rate elements.

               d.   -48 Volt Power. Provides -48 volt power to the Focal
                    collocated equipment. Charged on a per ampere basis.

               e.   48 Volt Power Cable. Provides for the transmission of -48
                    Volt DC power to the collocated equipment. It includes
                    engineering, furnishing and installing the main distribution
                    bay power breaker, associated power cable, cable rack and
                    local power bay to the closest power distribution bay. It
                    also includes the power cable (feeders) A and B from the
                    local power distribution bay to the leased physical space
                    (for physical collocation) or to the collocated equipment
                    (for virtual collocation).

               f.   Inspector Labor. Provides for the USWC qualified personnel
                    necessary when Focal requires access to the point of
                    interconnection after the initial installation or access to
                    its physical collocation floor space, where an escort is
                    required A call-out of an inspector after business hours is
                    subject to a minimum charge of four hours. The minimum
                    call-out charge shall apply when no other employee is
                    present in the location, and an `off-shift' USWC employee
                    (or contract employee) is required to go `on-shift' on
                    behalf of Focal.

               g.   Expanded Interconnection Channel Termination (EICT).
                    Telecommunications interconnection between Focal's
                    collocated equipment and USWC's network is accomplished via
                    an Expanded Interconnection Channel Termination (EICT). This
                    element can be at the DSO, DS1, DS3 or other level depending
                    on the USWC service it is connecting to. Connection to any
                    other network or telecommunications source within the wire
                    center is allowed only through USWC services.

               h.   Expanded Interconnection Channel Regeneration. Required when
                    the distance from the leased physical space (for physical
                    collocation) or from the collocated equipment (for virtual
                    collocation) to the USWC network is of sufficient length to
                    require regeneration.

          2.   Physical Collocation Rate Elements

               The following rate elements apply only to physical collocation
               arrangements:

               a.   Floor Space Rental. Provides the monthly rent for the leased
                    physical space, property taxes and base operating cost
                    without -48 Volt DC power. Includes convenience 110 AC, 15
                    amp electrical outlets provided in accordance with local
                    codes and may

                                    Page 27
<PAGE>
 
                    not be used to power transmission equipment or -48 Volt DC
                    power generating equipment. Also includes maintenance for
                    the leased space; provides for the preventative maintenance
                    (climate controls, filters, fire and life systems and
                    alarms, mechanical systems, standard HVAC); biweekly
                    housekeeping services (sweeping, spot cleaning, trash
                    removal) of the USWC wire center areas surrounding the
                    leased physical space and general repair and maintenance.

               b.   Enclosure Buildout. The Enclosure Buildout element, either
                    Cage or, at Focal's option, Hardwall, includes the material
                    and labor to construct the enclosure specified by Focal or
                    Focal may choose from USWC approved contractors to construct
                    the cage, meeting USWC's installation Technical Publication
                    77350. It includes the enclosure (cage or hardwall), air
                    conditioning (to support Focal loads specified), lighting
                    (not to exceed 2 watts per square foot), and convenience
                    outlets (3 per cage or number required by building code for
                    the hardwall enclosure). Also provides for humidification,
                    if required.

               c.   Pricing for the above physical collocation rate elements
                    will be provided on an individual basis due to the
                    uniqueness of Focal's requirements, central office structure
                    and arrangements.

          3.   Virtual Collocation Rate Elements

               The following rate elements apply uniquely to virtual
               collocation:

               a.   Maintenance Labor - Provides for the labor necessary for
                    repair of out of service and/or service-affecting conditions
                    and preventative maintenance of the Focal virtually
                    collocated equipment. Focal is responsible for ordering
                    maintenance spares. USWC will perform maintenance and/or
                    repair work upon receipt of the replacement maintenance
                    spare and/or equipment for Focal. A call-out of a
                    maintenance technician after business hours is subject to a
                    minimum charge as specified above.

               b.   Training Labor -- Provides for the billing of
                    vendor-provided training for USWC personnel on a
                    metropolitan service area basis, necessary for Focal
                    virtually collocated equipment which is different from USWC
                    provided equipment. USWC will require three USWC employees
                    to be trained per metropolitan service area in which the
                    Focal virtually collocated equipment is located. If, by an
                    act of USWC, trained employees are relocated, retired, or
                    are no longer available, USWC will not require Focal to
                    provide training for additional USWC employees for the same
                    virtually collocated equipment in the same metropolitan
                    area. The amount of training billed to Focal will be reduced
                    by half, should a second

                                    Page 28
<PAGE>
 
                    collocator in the same metropolitan area select the same
                    virtually collocated equipment as Focal.

               c.   Equipment Bay -- Provides mounting space for the Focal
                    virtually collocated equipment. Each bay includes the 7-foot
                    bay, its installation, and all necessary environmental
                    supports. Mounting space on the bay, including space for the
                    fuse panel and air gaps necessary for heat dissipation is
                    limited to 78 inches. The monthly rate is applied per shelf.

               d.   Engineering Labor -- Provides the planning and engineering
                    of the Focal virtually collocated equipment at the time of
                    installation, change or removal.

               e.   Installation Labor -- Provides for the installation, change
                    or removal of the Focal virtually collocated equipment.

     E.   Collocation Installation Intervals

          The following intervals are common to both virtual and physical
          collocation:

          1.   Acknowledgment of Floor Space Availability. Within fifteen days
               of the receipt by USWC from Focal of a Request for Collocation
               and an associated Quote Preparation Fee, USWC will notify Focal
               whether the sufficient floor space is available to accommodate
               Focal's request.

          2.   Quote Preparation. Within twenty-five business days of the
               receipt by USWC from Focal of a Request for Collocation and an
               associated Quote Preparation Fee, USWC provide Focal with a
               written quotation containing all nonrecurring charges for the
               requested collocation arrangement.

          3.   Quote Acceptance. Within thirty days of the receipt by Focal of
               the USWC quotation, Focal will accept the USWC proposed
               quotation. Acceptance shall require payment to USWC of fifty
               percent of the nonrecurring charges provided on the quotation.

          4.   Completion of Cage Construction (physical collocation only).
               Within 90 days of the acceptance of the quotation by Focal, the
               construction of the necessary cage/hardwall enclosure shall be
               completed. At this time, the leased floor space will be available
               to Focal for installation of its collocated equipment.

          5.   Completion of Collocated Equipment Installation (virtual
               collocation only) -- USWC shall complete the installation of
               Focal's collocated equipment within 90 days of USWC's receipt of
               Focal's collocated equipment. The installation of line cards and
               other minor modifications shall be performed by USWC on intervals
               equivalent to those that USWC applies to itself, but in no
               instance shall any such interval exceed 90 days.

                                    Page 29
<PAGE>
 
VII. INTERIM NUMBER PORTABILITY

     A.   General Terms

          1.   The Parties shall provide Number Portability on a reciprocal
               basis to each other to the extent technically feasible, and in
               accordance with rules and regulations as from time to time
               prescribed by the FCC and/or the Commission.

          2.   Until Number Portability is implemented by the industry pursuant
               to regulations issued by the FCC or the Commission, the Parties
               agree to provide Interim Telecommunications Number Portability
               ("INP") to each other through remote call forwarding, direct
               inward dialing and NXX migration.

          3.   Once permanent number portability is implemented pursuant to FCC
               or Commission regulation, either Party may withdraw, at any time
               and at its sole discretion, its INP offerings, subject to advance
               notice to the other Party and coordination to allow the seamless
               and transparent conversion of INP customer numbers to permanent
               number portability. Upon implementation of permanent number
               portability pursuant to FCC regulations, both parties agree to
               conform and provide such permanent number portability.

          4.   USWC will update its Line Information Database ("LIDB") listings
               for retained numbers, and restrict or cancel calling cards
               associated with these forwarded numbers as directed by Focal.
               LIDB updates shall be completed by the Parties on the same
               business day each INP arrangement is activated.

          5.   Upon request, USWC shall provide to Focal INP via Direct Inward
               Dial Trunks pursuant to applicable tariffs.

          6.   Where either party has activated an entire NXX for a single
               customer, or activated a substantial portion of an NXX for a
               single customer with the remaining numbers in that NXX either
               reserved for future use or otherwise unused, if such customer
               chooses to receive service from the other Party, the first Party
               shall cooperate with the second Party to have the entire NXX
               reassigned in the LERG (and associated industry databases,
               routing tables, etc.) to an End Office operated by the second
               Party. Such transfer will be accomplished with appropriate
               coordination between the Parties and subject to appropriate
               industry lead-times for movement of NXXs from one switch to
               another. Other applications of NXX migration will be discussed by
               the Parties as circumstances arise.

                                    Page 30
<PAGE>
 
     B.   Description of Service

          1.   Interim Number Portability Service ("INP") is a service
               arrangement that can be provided by USWC to Focal or by Focal to
               USWC. For the purposes of this section, the Party porting traffic
               to the other Party shall be referred to as the "INP Provider" and
               the Party receiving INP traffic for termination shall be referred
               to as the "INP Requestor".

          2.   INP applies to those situations where an end-user customer elects
               to transfer service from the INP Provider to the INP Requestor
               and they also wish to retain their existing telephone number. INP
               consists of INP Provider's provision to the INP Requestor the
               capability to route calls placed to telephone numbers assigned to
               the INP Provider's switches to the INP Requestor's switches. INP
               is available only for working telephone numbers assigned to the
               INP Provider's customers who request to transfer to the INP
               Requestor's service.

          3.   INP is available as INP-Remote Call Forwarding ("INP-RCF")
               permitting a call to a INP Provider's assigned telephone number
               to be translated to the INP Requestor's dialable local number.
               INP Requestor may terminate the call as desired. Additional
               capacity for simultaneous call forwarding is available where
               technically feasible. The INP Requestor will need to specify the
               number of simultaneous calls to be forwarded for each number
               ported.

          4.   INP is subject to the following restrictions:

               a.   An INP telephone number may be assigned by INP Requestor
                    only to the Requestor's customers located within the INP
                    Provider's local calling area and toll rating area that is
                    associated with the NXX of the portable number.

               b.   INP is applicable only if the INP Requestor is engaged in a
                    reciprocal traffic exchange arrangement with the INP
                    Provider.

               c.   Only the existing, INP Provider assigned end-user telephone
                    number may be used as a ported number for INP.

               d.   INP will not be provided by the INP Provider for customers
                    whose accounts are in arrears and who elect to make a change
                    of service provider unless and until the following
                    conditions are met:

                    i.   Full payment for the account (including
                         directory-advertising charges associated with the
                         customer's telephone number) is made by customer or INP
                         Requestor agrees to make full payment on behalf of
                         customer.

                                    Page 31
<PAGE>
 
                    ii.  INP Provider is notified in advance of the change in
                         service provider and a Change of Responsibility form is
                         issued.

                    iii. INP Provider accepts the transfer of responsibility.

               e.   INP services shall not be re-sold, shared or assigned by
                    either party to another LEC or CLEC.

               f.   INP is not offered for NXX Codes 555, 976, 960 and coin
                    telephones, and Service Access Codes (i.e. 500, 700,
                    800/888, 900). INP is not available for FGA seven-digit
                    numbers, including foreign exchange (FEX), FX and FX/ONAL
                    and foreign Central Office Service. Furthermore, INP numbers
                    may not be used for mass calling events.

               g.   The ported telephone number will be returned to the
                    originating company (or to the common pool of telephone
                    numbers upon implementation of permanent number portability)
                    when the ported service is disconnected. The company
                    purchasing a ported number may not retain it and reassign it
                    to another customer. The normal intercept announcement will
                    be provided by the INP Provider for the period of time until
                    the telephone number is reassigned by the Provider.

          5.   Ordering and Maintenance

               a.   The INP Requestor is responsible for all dealings with and
                    on behalf of its end users, including all end user account
                    activity, e.g. end user queries and complaints.

               b.   Each party is responsible for obtaining a Letter of
                    Authorization (LOA) from its end users that requests a
                    transfer of the end user's telephone number from the other
                    party.

               c.   The INP Provider will work cooperatively with the Requestor
                    to ensure a smooth customer transition and to avoid
                    unnecessary duplication of other facilities (e.g., unbundled
                    loops). The Parties will cooperate to develop intercompany
                    procedures to implement the requirements of this paragraph.

               d.   If an end user requests transfer of service from the INP
                    Requestor back to the INP Provider, the Provider may rely on
                    that end user request to institute cancellation of the INP
                    service. The INP Provider will provide at least 48 hours
                    notice to the INP Requestor of the cancellation of INP
                    service, and will work cooperatively with the Requestor to
                    ensure a smooth customer transition and to avoid unnecessary
                    duplication of other facilities (e.g., unbundled loops). The
                    Parties will cooperate to develop intercompany procedures
                    to implement the requirements of this paragraph.

                                    Page 32
<PAGE>
 
               e.   Certain features are not available on calls passed through
                    INP service.

               f.   The Requestor's designated INP switch must return answer and
                    disconnect supervision to the INP Provider's switch.

               g.   The Requestor will provide to the E91 1 database provider
                    the network telephone number that the Requestor assigned to
                    the Provider-assigned, ported telephone number. Updates to
                    and maintenance of the INP information to the E911 database
                    are the responsibility of the INP Requestor.

               h.   The INP Requestor will submit to the INP Provider a
                    disconnect order for each ported number that is relinquished
                    by the Requestor's end users.

          6.   Cost Recovery

               The parties agree that, for the purposes of this agreement that
               the following cost structure is an acceptable measure of the
               costs incurred by the INP Provider.

               a.   Number Ported -- This cost is incurred per number ported,
                    per month. Should the INP Requestor provide the transport
                    from the Provider's end office to the Requestor's end office
                    switch, a lower cost is incurred. This cost represents a
                    single call path from the Provider's end office switch to
                    the Requestor for the portable number.

               b.   Additional Call Path -- This cost is incurred per additional
                    call path per month added to a particular ported telephone
                    number. Should the INP Requestor provide the transport from
                    the Provider's end office to the Requestor's end office
                    switch, a lower cost is incurred.

               c.   Service Establishment -- Per Switch. This non-recurring cost
                    is incurred for each INP Provider's end office switch that
                    is equipped to provide INP to the INP Requestor.

               d.   Service Establishment -- Per Number -- This non-recurring
                    cost is for each telephone number equipped with INP.

               e.   The parties agree that Appendix A reasonably identifies the
                    above costs.


                                    Page 33
<PAGE>
 
                    (deleted)USWC position:

               f.   Each of the above costs should be borne by the INP
                    Requestor. MFS:(deleted)

               f.   Solely for the purposes of this arbitrated agreement between
                    USWC and Focal, these two parties agree to assign between
                    themselves, on an interim basis, interim number portability
                    costs on the basis of active local numbers, recognizing that
                    such assignment necessarily excludes recovery from other
                    industry participants. Each party is free to advocate the
                    assignment of interim number portability costs to other
                    industry participants as part of the appropriate industry-
                    wide cost recovery method. Section f has been incorporated
                    pursuant to the Arbitrator's decision in Docket UT-960323.

               g.   The parties shall, each quarter, exchange the confidential
                    data necessary to implement the above pro-rata assignment of
                    interim number portability costs.

               h.   The INP Provider will, when using RCF, send the original
                    ("ported") number over the interconnection arrangements as
                    the calling party number using the signaling protocol
                    applicable to the arrangements. The INP Requestor will
                    capture and measure the number of minutes of INP incoming
                    traffic. USWC will provide (and update quarterly) percentage
                    distributions of all terminating traffic in the LATA by
                    jurisdictional nature of the traffic: a) local; b)
                    intrastate, intraLATA switched access; c) intrastate,
                    interLATA switched access; d) interstate, intraLATA switched
                    access; e) interstate, interLATA switched access.. Separate
                    residence and business percentage distributions will be
                    provided, to the extent possible. The Parties agree to work
                    cooperatively to develop and exchange the data required to
                    implement this paragraph. The appropriate percentage will be
                    applied to the number of minutes of INP traffic in each
                    category to determine the number of minutes eligible for
                    additional "pass through" switched access compensation. Pass
                    through switched access compensation will be paid at the
                    following rates:

                    (deleted)USWC PROPOSAL:

                    For all intra LATA toll and inter LATA minutes delivered
                    over INP, USWC will pay, in addition to reciprocal
                    compensation, the applicable CCLC for each minute.

                    MFS PROPOSAL:(deleted)

                         For all intra-LATA toll and inter-LATA minutes
                         delivered over INP, USWC will pay, in lieu of
                         reciprocal

                                    Page 34
<PAGE>
 
                         compensation, all terminating switched access elements
                         otherwise due the terminating office provider,
                         including:

                              end office switching;
                              IC (interconnection charge);
                              CCLC; and
                              appropriate portion of tandem switched
                              transport.(6)

               i.   Rates are contained in Appendix A.

IX.  DIALING PARITY

     The Parties shall provide Dialing Parity to each other as required under
     Section 251 (b)(3) of the Act. This Agreement does not impact either
     Party's ability to default intraLATA toll via a specific dialing pattern
     until otherwise required by the Act.

X.   ACCESS TO TELEPHONE NUMBERS

     A.   Number Resources Arrangements.

          1.   Nothing in this Agreement shall be construed in any manner to
               limit or otherwise adversely impact either Party's right to the
               request and assignment of any NANP number resources including,
               but not limited to, central office (NXX) codes pursuant to the
               Central Office Code Assignment Guidelines (last published by the
               Industry Numbering Committee ("INC") as INC 95-0407-008, Revision
               4/19/96, formerly ICCF 93-0729-010). NXXs, and the initial points
               of interface for interconnection between the Parties' networks,
               will be included in Addenda to this Agreement.

          2.   To the extent USWC serves as Central Office Code Administrator
               for a given region, USWC will support all Focal requests related
               to central office (NXX) code administration and assignments in
               the manner required and consistent with the Central Office Code
               Assignment Guidelines.

          3.   The parties shall provide local dialing parity to each other as
               required under Section 251 (b)(3) of the Act.

- ---------
(6) The Parties recognize that the Arbitrator has ordered that the Parties
    incorporate a Provision in this Agreement requiring that "each carrier issue
    a bill to the IXC for its Portion of the access charges, based upon the
    functions and facilities provided by the carrier for call termination" and
    that the Parties' agreement should "take into account the fact that USWC
    receives compensation for INP costs by means of the Remote Call Forwarding
    charges". Because the Parties recognize that such a provision would incur
    additional costs and for purposes of consistency with other arbitrated
    results, the Parties agree to the above language.

                                    Page 35
<PAGE>
 
          4.   The Parties will comply with code administration requirements as
               prescribed by the Federal Communications Commission, the
               Commission, and accepted industry guidelines.

          5.   It shall be the responsibility of each Party to program and
               update its own switches and network systems pursuant to the Local
               Exchange Routing Guide (LERG) guidelines to recognize and route
               traffic to the other Party's assigned NXX codes at all times.
               Neither Party shall impose any fees or charges whatsoever on the
               other Party for such activities. The Parties will cooperate to
               establish procedures to ensure the timely activation of NXX
               assignments in their respective networks.

          6.   Each Party shall be responsible for notifying its customers of
               any changes in numbering or dialing arrangements to include
               changes such as the introduction of new NPAs or new NXX codes.

          7.   Until an impartial entity is appointed to administer
               telecommunications numbering and to make such numbers available
               on an equitable basis, USWC will assign NXX codes to Focal in
               accordance with national guidelines at no charge.

          8.   Each Party is responsible for administering NXX codes assigned to
               it. Each Party is responsible for obtaining Local Exchange
               Routing Guide ("LERG") listings of CLLI codes assigned to its
               switches. Each party shall use the LERG published by Bellcore or
               its successor for obtaining routing information and shall provide
               all required information to Bellcore for maintaining the LERG in
               a timely manner.

XI.  CALL COMPLETION FROM USWC OPERATORS

     USWC Operators will provide operator call completion and call completion
     and rating information and like assistance to any end user customer
     reaching USWC Operators (including information for calls to Focal NXXs) in
     the same manner as they provide such services for end user customers served
     by USWC NXXs and for calls involving only USWC NXXs.

XII. BUSY LINE VERIFY / INTERRUPT

     A.   Busy Line Verification ("BLV") is performed when one Party's Customer
          requests assistance from the operator bureau to determine if the
          called line is in use, however, the operator bureau will not complete
          the call for the Customer initiating the BLV inquiry. Only one BLV
          attempt will be made per Customer operator bureau call, and a charge
          shall apply whether or not the called party releases the line.

     B.   Busy Line Verification Interrupt ("BLVI") is performed when one
          Party's operator bureau interrupts a telephone call in progress after
          BLV has occurred. The operator bureau will interrupt the busy line and
          inform the called party that there

                                    Page 36
<PAGE>
 
          is a call waiting. The operator bureau will only interrupt the call
          and will not complete the telephone call of the Customer initiating
          the BLVI request. The operator bureau will make only one BLVI attempt
          per Customer operator telephone call and the applicable charge applies
          whether or not the called party releases the line.

     C.   The rate for Busy Line Verify shall be $.72 per call, and for Busy
          Line Verify and Interrupt, $.87 per call.

     D.   Each Party's operator bureau shall accept BLV and BLVI inquiries from
          the operator bureau of the other Party in order to allow transparent
          provision of BLV/BLVI Traffic between the Parties' networks.

     E.   Each Party shall route BLV/BLVI Traffic inquiries over separate direct
          trunks (and not the Local/IntraLATA Trunks) established between the
          Parties' respective operator bureaus. Unless otherwise mutually
          agreed, the Parties shall configure BLV/BLVI trunks over the
          Interconnection architecture defined in Section VI, Interconnection,
          consistent with the Joint Grooming Plan. Each Party shall compensate
          the other Party for BLV/BLVI Traffic as set forth above.

XIII. TOLL AND ASSISTANCE OPERATOR SERVICES

     A.   Description of Service.

               Toll and Assistance refers to functions customers associate with
               the "0" operator. Subject to availability and capacity, access
               may be provided via operator services trunks purchased from USWC
               or provided by Focal via collocation arrangements to route calls
               to Focal's platform.

     B.   Functions include:

          1.   O-Coin, Automatic Coin Telephone Service (ACTS) - these functions
               complete coin calls, collect coins and provide coin rates.

          2.   Alternate Billing Services (ABS or 0+ dialing): Bill to third
               party, Collect and Mechanized Credit Card System (MCCS).

          3.   O- or operator assistance which provides general assistance such
               as dialing instruction and assistance, rate quotes, emergency
               call completion and providing credit.

          4.   Automated Branding - ability to announce the carrier's name to
               the customer during the introduction of the call.

          5.   Rating Services - operators have access to tables that are
               populated with all toll rates used by the operator switch.

     C.   Pricing for Toll and Assistance Operator Services shall be determined
          on a case-by-case basis, upon request.

                                    Page 37
<PAGE>
 
     D.   Interconnection to the USWC Toll and Assistance Operator Services from
          an end office to USWC T/A is technically feasible at three distinct
          points on the trunk side of the switch. The first connection point is
          an operator services trunk connected directly to the T/A host switch.
          The second connection point is an operator services trunk connected
          directly to a remote T/A switch. The third connection point is an
          operator services trunk connected to a remote access tandem with
          operator concentration capabilities.

     E.   Trunk provisioning and facility ownership will follow the guidelines
          recommended by the Trunking and Routing, IOF and Switch sub-teams. All
          trunk interconnections will be digital.

     F.   Toll and Assistance interconnection will require an operator services
          type trunk between the end office and the interconnection point on the
          USWC switch.

     G.   Connecting a position to the host system requires two circuits (one
          voice and one data) per position on a T1 facility.

     H.   The technical requirements of operator services type trunks and the
          circuits to connect the positions to the host are covered in the OSSGR
          under Section 6 (Signaling) and Section 10 (System Interfaces) in
          general requirements form.

XIV. DIRECTORY ASSISTANCE

     A.   USWC agrees to (1) provide to Focal's operators on line access to
          USWC's directory assistance database; (2) provide to Focal unbranded
          directory assistance service (3) provide to Focal directory assistance
          service under Focal brand (where technically feasible); (4) allow
          Focal or an Focal designated operator bureau to license USWC's
          directory assistance database for use in providing competitive
          directory assistance services; and (5) in conjunction with (2) or (3)
          above, provide caller-optional directory assistance call completion
          service which is comparable in every way to the directory assistance
          call completion service USWC makes available to its own users and to
          provide caller name and number.

     B.   The price for directory assistance, provided pursuant to this
          Agreement, shall be 34 cents per call. As an alternative, the Parties
          may obtain directory assistance service pursuant to effective tariffs.

     C.   The price for directory call completion services shall be 35 cents per
          call, pending the completion of an approved TELRIC cost study.
          Additional charges, for USWC intraLATA toll services, also apply for
          completed intraLATA toll calls. Long distance service shall be
          available pursuant to the wholesale discount provided in Section XXX,
          Resale, herein. Call completion service is an optional service. Focal
          may, at its option, request USWC to not provide call completion
          services to Focal customers.

                                    Page 38
<PAGE>
 
XV.  DIRECTORY LISTINGS

     A.   Scope

          1.   Listings Service ("Listings") consists of USWC placing the names,
               addresses and telephone numbers of Focal's end users in USWC's
               listing database, based on end user information provided to USWC
               by Focal. USWC is authorized to use Listings in Directory
               Assistance (DA) and as noted in paragraph 4, below.

          2.   Focal will provide in standard, mechanized format, and USWC will
               accept at no charge, one primary listing for each main telephone
               number belonging to Focal's end user customers. Primary listings
               are as defined for USWC end users in USWC's general exchange
               tariffs. Focal will be charged for premium listings, e.g.,
               additional, foreign, cross-reference, informational, etc., at
               USWC's general exchange listing tariff rates. Focal utilizing
               Remote Call Forwarding for local number portability can list only
               one number without charge - either the end customer's original
               telephone number or the Focal-assigned number. The standard
               discounted rate for an additional listing applies to the other
               number.

          3.   USWC will furnish Focal the Listings format specifications. Focal
               may supply a maximum of one batch file daily, containing only
               Listings that completed on or prior to the transmission date.
               USWC cannot accept Listings with advance completion dates. Large
               volume activity (e.g., 100 or more listings) on a caption set is
               considered a project that requires coordination between Focal and
               USWC to determine time frames.

          4.   Focal grants USWC a non-exclusive license to incorporate Listings
               information into its directory assistance database. Focal hereby
               selects one of two options for USWC's use of Listings and
               dissemination of Listings to third parties.

                    EITHER:

               a.   Treat the same as USWC's end user listings - No prior
                    authorization is needed for USWC to release Listings to
                    directory publishers or other third parties. USWC will
                    incorporate Listings information in all existing and future
                    directory assistance applications developed by USWC. Focal
                    authorizes USWC to sell and otherwise make Listings
                    available to directory publishers. USWC shall be entitled to
                    retain all revenue associated with any such sales. Listings
                    shall not be provided or sold in such a manner as to
                    segregate end users by carrier.

                    OR:

               b.   Restrict to USWC's directory assistance -- Prior
                    authorization required by Focal for all other uses. Focal
                    makes its own,

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<PAGE>
 
                    separate agreements with USWC, third parties and directory
                    publishers for all uses of its Listings beyond DA. USWC will
                    sell Listings to directory publishers (including USWC's
                    publisher affiliate), other third parties and USWC products
                    only after the third party presents proof of Focal's
                    authorization. USWC shall be entitled to retain all revenue
                    associated with any such sales. Listings shall not be
                    provided or sold in such a manner as to segregate end users
                    by carrier.

          5.   To the extent that state tariffs limit USWC's liability with
               regard to Listings, the applicable state tariff(s) is
               incorporated herein and supersedes Section XXXIV(U), "Limitation
               of Liability", of this Agreement with respect to Listings only.

     B.   USWC Responsibilities

          1.   USWC is responsible for maintaining Listings, including entering,
               changing, correcting, rearranging and removing Listings in
               accordance with Focal orders. USWC will take reasonable steps in
               accordance with industry practices to accommodate non-published
               and non-listed Listings provided that Focal has supplied USWC the
               necessary privacy indicators on such Listings.

          2.   USWC will include Focal Listings in USWC's Directory Assistance
               service to ensure that callers to USWC's Directory Assistance
               service have nondiscriminatory access to Focal's Listings.

          3.   USWC will incorporate Focal Listings provided to USWC in the
               White Pages directory published on USWC's behalf.

     C.   Focal Responsibilities

          1.   Focal agrees to provide to USWC its end user names, addresses and
               telephone numbers in a standard mechanized format, as specified
               by USWC.

          2.   Focal will supply its ACNA/CIC or CLCC/OCN, as appropriate, with
               each order to provide USWC the means of identifying Listings
               ownership.

          3.   Focal represents and warrants the end user information provided
               to USWC is accurate and correct. Focal further represents and
               warrants that it has reviewed all Listings provided to USWC,
               including end user requested restrictions on use such as
               non-published and non-listed. Focal shall be solely responsible
               for knowing and adhering to state laws or rulings regarding
               Listings (e.g., no solicitation requirements in the states of
               Arizona and Oregon, privacy requirements in Colorado), and for
               supplying USWC with the applicable Listing information.

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<PAGE>
 
          4.   Focal is responsible for all dealings with, and on behalf of,
               Focal's end users, including:

               a.   All end user account activity, e.g. end user queries and
                    complaints.

               b.   All account maintenance activity, e.g., additions, changes,
                    issuance of orders for Listings to USWC.

               c.   Determining privacy requirements and accurately coding the
                    privacy indicators for Focal's end user information. If end
                    user information provided by Focal to USWC does not contain
                    a privacy indicator, no privacy restrictions will apply.

               d.   Any additional services requested by Focal's end users.

     D.   The terms contained in this Section refer specifically to the
          provision of Listings from Focal to USWC. The Parties acknowledge that
          the Telecommunications Act of 1996 imposes reciprocal obligations on
          incumbent and new entrant Local Exchange providers with respect to
          directory assistance listings and white pages listings. As a result,
          the Parties agree that the terms in this Section are reciprocal and
          also include the provision of Listings from USWC to Focal, in the
          event that Focal provides its own directory assistance service or
          publishes its own white pages directory.

XVI. U S WEST DIRECT ISSUES

     USWC and Focal agree that certain issues, such as yellow page advertising,
     directory distribution, access to call guide pages, yellow page listings,
     will be the subject of negotiations between Focal and directory publishers,
     including U S WEST Direct. USWC acknowledges that Focal may request USWC to
     facilitate discussions between Focal and U S WEST Direct.

XVII. ACCESS TO POLES, DUCTS, CONDUITS, AND RIGHTS OF WAY

     Each Party shall provide the other Party access to its poles, ducts,
     rights-of-way and conduits it controls on terms, conditions and prices
     comparable to those offered to any other entity pursuant to each party's
     applicable tariffs and/or standard agreements.

XVIII. ACCESS TO DATABASES

     In accordance with Section 271 of the Act, USWC shall provide Focal with
     interfaces to access USWC's databases and associated signaling necessary
     for the routing and completion of Focal's traffic. Except where otherwise
     specified, access to such databases, and the appropriate interfaces, shall
     be made available to Focal via a Network Interconnection and Unbundled
     Element Request.

                                    Page 41
<PAGE>
 
XIX. NOTICE OF CHANGES

     If a Party makes a change in its network, which it believes will materially
     affect the inter-operability of its network with the other Party, the Party
     making the change shall provide advance notice of such change to the other
     Party in accordance with the applicable FCC regulations.

XX.  911 / E-911 SERVICE

     A.   Scope.

          1.   Focal exchanges to be included in USWC's E-911 DataBase will be
               indicated via written notice and will not require an amendment to
               this Agreement.

          2.   In counties where USWC has obligations under existing agreements
               as the primary provider of the 911 System to the county, Focal
               will participate in the provision of the 911 System as described
               in this Agreement.

               a.   Each party will be responsible for those portions of the 911
                    System for which it has total control, including any
                    necessary maintenance to each Party's portion of the 911
                    System.

               b.   USWC will be responsible for maintaining the E-911
                    Database. USWC will provide a copy of the Master Street
                    Address Guide ("MSAG"), and periodic updates, to Focal.

               c.   Focal assumes all responsibility for the accuracy of the
                    data that Focal provides to USWC for MSAG preparation and
                    E-911 Data Base operation.

               d.   Focal will provide end user data to the USWC ALI database
                    utilizing NENA-02-001 Recommended Formats For Data Exchange,
                    NENA-02-002 Recommended Standard For Street Thoroughfare
                    Abbreviations and NENA-02-003 Recommended Protocols For Data
                    Exchange. USWC will furnish Focal any variations to NENA
                    recommendations required for ALI database input.

               e.   Focal will provide end user data to the USWC ALI data base
                    that are Master Street Address Guide (MSAG) valid and meet
                    all components of the NENA-02-004 Recommended Measurements
                    For Data Quality.

               f.   Focal will update its end user records provided to the USWC
                    ALI database to agree with the 911 MSAG standards for its
                    service areas.
 
                                    Page 42
<PAGE>
 
               g.   USWC will provide Focal with the identification of the USWC
                    911 controlling office that serves each geographic area
                    served by Focal.

               h.   The Parties will cooperate in the routing of 911 traffic in
                    those instances where the ALI/ANI information is not
                    available on a particular 911 call.

               i.   USWC will provide Focal with the ten-digit telephone numbers
                    of each PSAP agency, for which USWC provides the 911
                    function, to be used by Focal operators for handling
                    emergency calls in those instances where the Focal customer
                    dials "0" instead of "911".

          3.   If a third party; i.e., LEC, is the primary service provider to a
               county, Focal will negotiate separately with such third party
               with regard to the provision of 911 service to the county. All
               relations between such third party and Focal are totally separate
               from this Agreement and USWC makes no representations on behalf
               of the third party.

          4.   If Focal is the primary service provider to the county, Focal and
               USWC will negotiate the specific provisions necessary for
               providing 911 service to the county and will include such
               provisions in an amendment to this Agreement.

          5.   Focal will separately negotiate with each county regarding the
               collection and reimbursement to the county of applicable customer
               taxes for 911 service.

          6.   Focal is responsible for network management of its network
               components in compliance with the Network Reliability Council
               Recommendations and meeting the network standard of USWC for the
               911 call delivery.

          7.   The parties shall provide a single point of contact to coordinate
               all activities under this Agreement.

          8.   Neither Party will reimburse the other for any expenses incurred
               in the provision of E-911 services.

     B.   Performance Criteria. E-911 Data Base accuracy shall be as set forth
          below:

          1.   Accuracy of ALI (Automatic Location Identification) data will be
               measured jointly by the PSAP's (Public Safety Answering Points)
               and USWC in a format supplied by USWC. The reports shall be
               forwarded to Focal by USWC when relevant and will indicate
               incidents when incorrect or no ALI data is displayed.

          2.   Each discrepancy report will be jointly researched by USWC and
               Focal. Corrective action will be taken immediately by the
               responsible party.
 
                                    Page 43
<PAGE>
     
          3.   Each party will be responsible for the accuracy of its customer
               records. Each party specifically agrees to indemnify and hold
               harmless the other party from any claims, damages, or suits
               related to the accuracy of customer data provided for inclusion
               in the E-911 Data Base.

          4.   The additional parameters by which the Parties will utilize the
               911 or E-911 database will be the subject of further discussion
               between the parties.

XXI. REFERRAL ANNOUNCEMENT

     When an end user customer changes from USWC to Focal, or from Focal to
     USWC, and does not retain their original telephone number, the Party
     formerly providing service to the end user will provide a transfer of
     service announcement on the abandoned telephone number. Each Party will
     provide this referral service consistent with its tariff. This announcement
     will provide details on the new number that must be dialed to reach this
     customer.

XXII. COORDINATED REPAIR CALLS

     A.   Focal and USWC will employ the following procedures for handling
          misdirected repair calls;

          1.   Focal and USWC will provide their respective customers with the
               correct telephone numbers to call for access to their respective
               repair bureaus.

          2.   Customers of Focal shall be instructed to report all cases of
               trouble to Focal. Customers of USWC shall be instructed to report
               all cases of trouble to USWC.

          3.   To the extent the correct provider can be determined, misdirected
               repair calls will be referred to the proper provider of Basic
               Exchange Telecommunications Service.

          4.   Focal and USWC will provide their respective repair contact
               numbers to one another on a reciprocal basis.

          5.   In responding to repair calls, neither Party shall make
               disparaging remarks about each other, nor shall they use these
               repair calls as the basis for internal referrals or to solicit
               customers to market services. Either Party may respond with
               accurate information in answering customer questions.

XXIII. NETWORK INTERCONNECTION AND UNBUNDLED ELEMENT REQUEST

     A.   Any request for interconnection or access to an unbundled Network
          Element that is not already available as described herein shall be
          treated as a Network

                                    Page 44
<PAGE>
 
          Interconnection and Unbundled Element Request (NIUER). USWC shall use
          the NIUER Process to determine technical feasibility of the requested
          interconnection or Network Elements and, for those items found to be
          feasible, to provide the terms and timetable for providing the
          requested items.

     B.   A NIUER shall be submitted in writing and shall, at a minimum,
          include: (a) a technical description of each requested Network Element
          or interconnection; (b) the desired interface specification; (c) each
          requested type of interconnection or access; (d) a statement that the
          interconnection or Network Element will be used to provide a
          telecommunications service; and (e) the quantity requested.

     C.   Within 15 business days of its receipt, USWC shall acknowledge receipt
          of the NIUER and in such acknowledgment advise Focal of any missing
          information, if any, necessary to process the NIUER. Thereafter, USWC
          shall promptly advise Focal of the need for any additional information
          that will facilitate the analysis of the NIUER.

     D.   Within 30 calendar days of its receipt of the NIUER and all
          information necessary to process it, USWC shall provide to Focal a
          preliminary analysis of the NIUER. The preliminary analysis shall
          specify: (a) USWC's conclusions as to whether or not the requested
          interconnection or access to an unbundled Network Element is
          technically feasible; and (b) any objections to qualification of the
          requested Network Element or interconnection under the Act.

          1.   If USWC determines during the 30 day period that a NIUER is not
               technically feasible or that the NIUER otherwise does not qualify
               as a Network Element of interconnection that is required to be
               provided under the Act, USWC shall advise Focal as soon as
               reasonably possible of that fact, and USWC shall promptly, but in
               no case later than ten days after making such a determination,
               provide a written report setting forth the basis for its
               conclusion.

          2.   If USWC determines during the thirty-day period that the NIUER is
               technically feasible and otherwise qualifies under the Act, it
               shall notify Focal in writing of such determination within ten
               days.

          3.   As soon as feasible, but in any case within 90 days after USWC
               notifies Focal that the NIUER is technically feasible, USWC shall
               provide to Focal a NIUER quote which will include, at a minimum,
               a description of each interconnection and Network Element, the
               quantity to be provided, any interface specifications, and the
               applicable rates (recurring and nonrecurring) including the
               separately stated amortized development costs of the
               interconnection or the network elements and any minimum volume
               and term commitments required to achieve amortization of
               development costs. An initial payment for development cost is
               appropriate only where Focal is the only conceivable customer or
               where requested quantity is insufficient to provide amortization.

                                    Page 45
<PAGE>
 
     E.   If USWC has indicated minimum volume and term commitments, then within
          30 days of its receipt of the NIUER quote, Focal must either agree to
          purchase under those commitments, cancel its NIUER, or seek mediation
          or arbitration.

     F.   If Focal has agreed to minimum volume and term commitments under the
          preceding paragraph, Focal may cancel the NIUER or volume and term
          commitment at any time, but in the event of such cancellation Focal
          will pay USWC's reasonable development costs incurred in providing the
          interconnection or network element, to the extent that those
          development costs are not otherwise amortized.

     G.   If either Party believes that the other Party is not requesting,
          negotiating or processing any NIUER in good faith, or disputes a
          determination, or quoted price or cost, it may seek arbitration or
          mediation under S 252 of the Act. Focal is not required to use this
          section as the exclusive method of seeking access to interconnection
          or Network Elements.

XXIV. AUDIT PROCESS

     A.   "Audit" shall mean the comprehensive review of:

          1.   data used in the billing process for services performed and
               facilities provided under this Agreement; and

          2.   data relevant to provisioning and maintenance for services
               performed or facilities provided by either of the Parties for
               itself or others that are similar to the services performed or
               facilities provided under this Agreement for interconnection or
               access to unbundled elements.

     B.   The data referred to in subsection (2), above, shall be relevant to
          any performance standards that are adopted in connection with this
          Agreement, through negotiation, arbitration or otherwise.

     C.   This Audit shall take place under the following conditions:

          1.   Either Party may request to perform an Audit.

          2.   The Audit shall occur upon 30 business days written notice by the
               requesting Party to the non-requesting Party.

          3.   The Audit shall occur during normal business hours.

          4.   There shall be no more than one Audit requested by each Party
               under this Agreement in any 12-month period.

          5.   The requesting Party may review the non-requesting Party's
               records, books and documents, as may reasonably contain
               information relevant to the operation of this Agreement.
  
                                    Page 46
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          6.   The location of the Audit shall be the location where the
               requested records, books and documents are retained in the normal
               course of business.

          7.   All transactions under this Agreement which are over 24 months
               old will be considered accepted and no longer subject to Audit.

          8.   Each Party shall bear its own expenses occasioned by the Audit,
               provided that the expense of any special data collection shall be
               born by the requesting Party.

          9.   The Party requesting the Audit may request that an Audit be
               conducted by a mutually agreed-to independent auditor. Under this
               circumstance, the costs of the independent auditor shall be paid
               for by the Party requesting the Audit.

          10.  In the event that the non-requesting Party requests that the
               Audit be performed by an independent auditor, the Parties shall
               mutually agree to the selection of the independent auditor. Under
               this circumstance, the costs of the independent auditor shall be
               shared equally by the Parties.

          11.  The Parties agree that if an Audit discloses error(s), the Party
               responsible for the error(s) shall, in a timely manner, undertake
               corrective action for such error(s).

     D.   All information received or reviewed by the requesting Party or the
          independent auditor in connection with the Audit is to be considered
          Proprietary Information as defined by this Agreement. The
          non-requesting Party reserves the right to require any non-employee
          who is involved directly or indirectly in any Audit or the resolution
          of its findings as described above to execute a nondisclosure
          agreement satisfactory to the non-requesting Party. To the extent an
          Audit involves access to information of other competitors, Focal and
          USWC will aggregate such competitors' data before release to the other
          Party, to insure the protection of the proprietary nature of
          information of other competitors. To the extent a competitor is an
          affiliate of the party being audited (including itself and its
          subsidiaries), the Parties shall be allowed to examine such
          affiliates' disaggregated data, as required by reasonable needs of the
          audit.

XXV. AUDIOTEXT AND MASS ANNOUNCEMENT SERVICES

     A.   The Parties agree that access to the audiotext, mass announcement and
          information services of each Party should be made available to the
          other Party upon execution of an agreement defining terms for billing
          and compensation of such calls. Services included in this category
          include 976 calls, whether flat rated or usage sensitive, intra-LATA
          900 services and other intra-LATA 976-like services. Such calls will
          be routed over the Local Interconnection Trunks.

     B.   Focal and USWC will work together in good faith to negotiate and
          execute the agreement for billing and compensation for these services
          within 90 days of the

                                    Page 47
<PAGE>
 
          execution of this Agreement. The Parties agree that their separate
          agreement on audiotext and mass announcement services will include
          details concerning the creation, exchange and rating of records, all
          of which will occur without any explicit charge between the Parties,
          as well as a process for the handling of uncollectables so that the
          originating Party does not have any responsibility for uncollectables.

     C.   Until such time that such an agreement is executed, Focal may choose
          to block such calls, or Focal will agree to back-bill and compensate
          retroactively for such calls once the subsequent agreement is executed
          retroactive to the effective date of this Agreement.

     D.   Usage Sensitive Compensation

          All audiotext and mass announcement calls shall be considered toll
          calls for purposes of reciprocal compensation between the Parties.
          Compensation will be paid based on the compensation for toll calls
          referenced in this Agreement with respect to reciprocal compensation
          between the Parties, except that such compensation shall be paid by
          the Party terminating the call, rather than the Party originating the
          call.

     E.   Billing and Collection Compensation

          Billing and collection compensation will be dealt with in the
          agreement referenced in this section.

XXVI. LOCAL INTERCONNECTION DATA EXCHANGE FOR BILLING

     A.   There are certain types of calls or types of interconnection that
          require exchange of billing records between the Parties, including,
          for example, alternate billed and Toll Free Service calls. The Parties
          agree that all call types must be routed between the networks,
          accounted for, and settled among the parties. Certain calls will be
          handled via the Parties' respective operator service platforms. The
          Parties agree to utilize, where possible and appropriate, existing
          accounting and settlement systems to bill, exchange records and settle
          revenue.
 
     B.   The exchange of billing records for alternate billed calls (e.g.
          calling card, bill-to-third number, and collect) will be distributed
          through the existing CMDS processes, unless otherwise separately
          agreed to by the Parties.

     C.   Inter-Company Settlements ("ICS") revenues will be settled through the
          Calling Card and Third Number Settlement System ("CATS"). Each Party
          will provide for its own arrangements for participation in the CATS
          processes, through direct participation or a hosting arrangement with
          a direct participant.

     D.   Non-ICS revenue is defined as collect calls, calling card calls, and
          billed to third number calls which originate on one service provider's
          network and terminate on another service provider's network in the
          same Local Access Transport Area ("LATA"). The Parties agree to
          negotiate and execute an Agreement within 30

                                    Page 48
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          days of the execution of this Agreement for settlement of non-ICS
          revenue. This separate arrangement is necessary since existing CATS
          processes do not permit the use of CATS for non-ICS revenue. The
          Parties agree that the CMDS system can be used to transport the call
          records for this traffic.

     E.   Both Parties will provide the appropriate call records to the
          intraLATA Toll Free Service Provider, thus permitting the Service
          Provider to bill its subscribers for the inbound Toll Free Service. No
          adjustments to bills via tapes, disks or NDM will be made without the
          mutual agreement of the Parties.

XXVII. SIGNALING ACCESS TO CALL-RELATED DATABASES

     A.   When Focal is purchasing local switching from USWC, USWC will provide
          access via the STP to call related databases used in AIN services. The
          Parties agree to work in the industry to define the mediated access
          mechanisms for SCP access. Access to the USWC SMS will be provided to
          CLEC to create, modify, or update information in the call related
          databases, equivalent to the USWC access.

     B.   USWC will offer unbundled signaling via LIS-Common Channel Signaling
          Capability (CCSAC). CCSAC service utilizes the SS7 network and
          provides access to call-related databases that reside at USWC'S SCPs,
          such as the Line Information Database (LIDB) and the 800 Database. The
          access to USWC's SCP's will be mediated via the STP Port in order to
          assure network reliability.

     C.   CCSAC includes:

          1.   Entrance Facility - This element connects Focal's signaling point
               of interface with the USWC serving wire center (SWC). Focal may
               purchase this element or it may self-provision the entrance
               facility. If the entrance facility is self-provisioned, Focal
               would need to purchase collocation and an expanded
               interconnection channel termination.

          2.   Direct Link Transport (DLT) - This element connects the SWC to
               the USWC STP. Focal may purchase this element or self-provision
               transport directly to the STP. If Focal provides the link to the
               STP, it must purchase collocation and an expanded interconnection
               channel termination at the STP location.

          3.   STP Port - This element provides the switching function at the
               STP. One STP Port is required for each DLT Link. The Port
               provides access to the Service Control Point (SCP).

     D.   Access to Advanced Intelligent Network (AIN) functions is available
          only through the STP.

     E.   USWC will provide access to Service Management Systems (SMS) through
          its Service Creation Environment (SCE) on an equivalent basis as USWC
          provides

                                    Page 49
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          to itself. SMS allows Focal to create, modify, or update information
          in call-related databases. Currently, the SCE process is predominantly
          manual.

     F.   The pricing for CCSAC service is provided in Appendix A.

XXVIII. INTERCONNECTION TO LINE INFORMATION DATA BASE (LIDB)

     A.   Description of Line Information Data Base (LIDB).

          Line Information Data Base (LIDB) stores various line numbers and
          Special Billing Number (SBN) data used by operator services systems to
          process and bill calls. The operator services system accesses LIDB
          data to provide origination line (calling number), billing number and
          termination line (called number) management functions. LIDB is used
          for calling card validation, fraud verification, preferred IC
          association with the calling card, billing or service restrictions and
          the sub-account information to be included on the call's billing
          record.

     B.   Interfaces.

          Bellcore's GR-446-CORE defines the interface between the
          administration system and LIDB including specific message formats.
          (Bellcore's TR-NWP000029, Section 10)

     C.   LIDB Access.

          1.   All LIDB queries and responses from operator services systems and
               end offices are transmitted over a CCS network using a Signaling
               System 7 (557) protocol (TR-NWT-000246, Bell Communications
               Research Specification of Signaling System 7).

          2.   All LIDB queries and responses from the Public Packet Switched
               Network (PPSN) nodes are transmitted over one or more PPSN as
               TR-TSYOOO3O1 describes. The application data needed for
               processing LIDB data are formatted as TCAP messages. TCAP
               messages may be carried as an application level protocol network
               using 5S7 protocols for basic message transport.

          3.   The SCP node provides all protocol and interface support. CLEC
               SS7 connections will be required to meet Bellcore's GR905. TR954
               and USWC's Technical Publication 77342 specifications.

          4.   Non-USWC companies will submit LIDB updates through the exchange
               carrier service center and the LSS service bureau. These two
               centers enter information into USWC's service order process
               interface system, SOPI.

          5.   It is currently USWC's policy to allow LIDB access to non-USWC
               companies through regional STPs.

                                    Page 50
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     D.   Pricing for LIDB access shall be determined on a case-by-case basis.

XXIX. CONSTRUCTION CHARGES

     Pursuant to the Arbitrator's decision in Docket UT-960323, USWC may not
     assess separate "construction" charges in addition to the rate for
     unbundling and provisioning the local loop. USWC may still assess
     construction charges where they are provided for by tariff. In addition,
     construction charges proposals can be further reviewed in the generic
     pricing proceeding. With regard to resale, Focal will pay those
     construction charges that would be applicable to the end-user if the
     end-user ordered the same service directly from USWC.

     (deleted)USWC Proposal:

     A.   All rates, charges and initial service period specified in this
          Agreement contemplates the provision of network interconnection
          services, equipment and facilities to the extent available. Where USWC
          is required to build facilities for network interconnection,
          construction charges will apply. Construction charges will also apply
          when USWC determines that the placement of facilities will be
          temporary, or facilities are ordered in advance of actual MFS demand
          for service.

     B.   When facilities for interconnection services are not available and
          USWC is required to construct said facilities, USWC will develop the
          cost required to be paid by MFS to provide the service.

     C.   Except where required, all necessary construction will be undertaken
          at the discretion of USWC, consistent with budgetary responsibilities
          and consideration for the impact on the general body of customers.

     D.   A quote for the MFS portion of a specific job will be provided to MFS.
          The quote will be in writing and will be binding for ninety (90) days
          after the issue date. When accepted, MFS will be billed the quoted
          price and construction will commence after receipt of payment. If MFS
          chooses not to have USWC construct the facilities, USWC reserves the
          right to bill MFS for the expense incurred for producing the
          engineered job design.

     E.   In the event a construction charge is applicable, MFS service
          application date will become the date upon which USWC receives the
          required payment.

     MFS Position:

          No provisions for construction charges are required or justified under
          the Act or regulations. An appropriately performed TELRIC study
          provides recovery of all costs, including construction.(deleted)

                                    Page 51
<PAGE>
 
XXX. RESALE

     A.   Description

          1.   USWC Basic Exchange Telecommunications Service (as defined in
               Section III) will be available for resale from USWC pursuant to
               the Act and will reference terms and conditions (except prices)
               in USWC tariffs, where applicable. Appendix A lists services
               which are available for resale under this Agreement, and is
               attached and incorporated herein by this reference.

          2.   Certain USWC services are not available for resale under this
               Agreement. USWC's Telecommunication Services which are not
               available for resale are identified in Appendix A.

          3.   Certain USWC services shall be available for resale at prices
               absent a wholesale discount. Such services include residence
               exchange service, private line, special access and switched
               access services, and packages of services comprised of services
               available for resale separately. These services are listed in
               Appendix A.

          4.   Focal may contest the legality of any resale restrictions in a
               USWC retail tariff through a complaint filed with the State
               Commission.

     B.   Scope

          1.   Basic Exchange Telecommunications Service may be resold only to
               the same class of customer to which USWC sells local Basic
               Exchange Telecommunications Service. For example:

               a.   Residence service may not be resold to business customers;

               b.   Basic Exchange Telecommunications Service may not be resold
                    as a substitute for switched access service.

               c.   Pursuant to the Arbitrator's Decision in Docket UT-960323,
                    USWC's proposed paragraph has been deleted.
                    (deleted)Telecommunications Service may be resold only for
                    its intended or disclosed use.(deleted)

          2.   USWC shall bill Focal and Focal is responsible for all applicable
               charges for the resold services. Focal shall be responsible for
               all charges associated with services that Focal resells to an end
               user.

     C.   Ordering and Maintenance.

          1.   Focal, or Focal's agent, shall act as the single point of contact
               for its end users' service needs, including without limitation,
               sales, service design

                                    Page 52
<PAGE>
 
               order taking, provisioning, change orders, training, maintenance,
               trouble reports, repair, post-sale servicing, billing, collection
               and inquiry. Focal shall make it clear to its end users that they
               are customers of the Focal for resold services. Focal's end users
               contacting USWC will be instructed to contact Focal; however,
               nothing in this Agreement shall be deemed to prohibit USWC from
               discussing its products and services with Focal's customers who
               call USWC for any reason.

          2.   Focal shall transmit to USWC all information necessary for the
               installation (billing, listing and other information), repair,
               maintenance and post-installation servicing according to USWC's
               standard procedures, as described in the USWC resale operations
               guide that will be provided to Focal. When USWC's end user or the
               end user's new service provider discontinues the end user's
               service in anticipation of moving to another service provider,
               USWC will render its closing bill to end user customer effective
               with the disconnection. Should Focal's end user customer, a new
               service provider or Focal request service be discontinued to the
               end user, USWC will issue a bill to Focal for that portion of the
               service provided to Focal. USWC will notify Focal by FAX, EDI, or
               other processes when end user moves to another service provider.
               Focal shall issue disconnect orders to USWC, which shall be
               coordinated with new connect orders issued by the new service
               provider

          3.   Resold services shall be installed and repaired in a manner
               consistent with USWC's effective tariffs with the same quality
               and timeliness that USWC provides to its own end users.

          4.   Focal shall provide USWC and USWC shall provide Focal with points
               of contact for order entry, problem resolution and repair of the
               resold services.

          5.   Prior to placing orders on behalf of the USWC customer, Focal
               shall be responsible for obtaining and have in its possession a
               Letter of Authorization or Agency (LOA) from the end user. Focal
               shall make LOAs available to USWC upon request.

          6.   Prior to placing orders that will disconnect a line from another
               reseller's account Focal is responsible for obtaining all
               information needed to process the disconnect order and
               re-establish the service on behalf of the end user. If Focal is
               displaced by another reseller or service provider, Focal is
               responsible for coordination with the other reseller or service
               provider. Should an end user dispute or a discrepancy arise
               regarding the authority of Focal to act on behalf of the end
               user, Focal is responsible for providing written evidence of its
               authority to USWC within three (3) business days. If there is a
               conflict between the end user designation and Focal's written
               evidence or its authority, USWC shall honor the designation of
               the end user and change the end user back to the previous service
               provider. If Focal does not provide the LOA within

                                    Page 53
<PAGE>
 
               three (3) business days, or if the end user disputes the
               authority of the LOA, then Focal must, by the end of the third
               business day:

               a.   notify USWC to change the end user back to the previous
                    reseller or service provider, and

               b.   provide any end user information and billing records Focal
                    has obtained relating to the end user to the previous
                    reseller, and

               c.   notify the end user and USWC that the change has been made,
                    and

               d.   remit to USWC a slamming charge as provided in Appendix A as
                    compensation for the change back to the previous reseller or
                    service provider.

          7.   Focal shall designate the Primary Interexchange Carrier (PIC)
               assignments on behalf of its end users for interLATA services and
               intraLATA services when intraLATA presubscription is implemented.

     D.   Focal Responsibilities

          1.   Focal must send USWC complete and accurate end-user listing
               information for Directory Assistance, Directory, and 911
               Emergency Services using the established processes of USWC. Focal
               must provide to USWC accurate end-user information to ensure
               appropriate listings in any databases in which USWC is required
               to retain and/or maintain end-user information. USWC assumes no
               liability for the accuracy of information provided by Focal.

          2.   Focal may not reserve blocks of USWC telephone numbers, except as
               allowed by tariffs.

          3.   Focal is liable for all fraud associated with service to its
               end-users and accounts. USWC takes no responsibility, and will
               make no adjustments to Focal's account in cases of fraud. The
               Parties will cooperate in the prevention and investigation of
               fraudulent use of resold services.

          4.   This agreement does not address the resale of USWC provided
               calling cards.

          5.   Focal will provide a three year forecast within ninety (90) days
               of signing this Agreement. The forecast shall be updated and
               provided to USWC on a quarterly basis in as specified in Appendix
               B. The initial forecast will provide:

               a.   The date service will be offered (by city and/or state)
               b.   The type and quantity of service(s) which will be offered
               c.   Focal's anticipated order volume

                                    Page 54
<PAGE>
 
               d.   Focal's key contact personnel.

          6.   In the event USWC terminates the provisioning of any resold
               services to Focal for any reason, Focal shall be responsible for
               providing any and all necessary notice to its end users of the
               termination. In no case shall USWC be responsible for providing
               such notice.

     E.   Rates and Charges

          1.   Resold services as listed in Appendix A are available for resale
               at the applicable resale tariff rates or at the rates or at the
               wholesale discount levels set forth in Appendix A.

          2.   If the resold services are purchased pursuant to Tariffs and the
               Tariff rates change, charges billed to Focal for such services
               will be based upon the new Tariff rates less the applicable
               wholesale discount as agreed to herein. The new rate will be
               effective upon the Tariff effective date.

          3.   A Customer Transfer Charge (CTC) as specified in Appendix A
               applies when transferring any existing account or lines to Focal.

          4.   A Subscriber Line Charge (SLC) will continue to be paid by Focal
               without discount for each local exchange line resold under this
               Agreement. All federal and state rules and regulations associated
               with SLC as found in the applicable tariffs also apply.

          5.   Focal will pay to USWC the PIC change charge without discount
               associated with Focal end user changes of inter-exchange or
               intraLATA carriers.

          6.   Focal agrees to pay USWC when its end user activates any services
               or features that are billed on a per use or per activation basis
               (e.g., continuous redial, last call return, call back calling,
               call trace, etc.). USWC shall provide Focal with detailed billing
               information (per applicable OBF standards, if any) as necessary
               to permit Focal to bill its end users such charges.

          7.   To the extent such charges apply to USWC's retail customers,
               special construction charges, line extension charges, and land
               development agreements may apply to Focal, as detailed in
               individual state tariffs regarding end user obligations for
               construction charges. Specifically, special construction charges
               will be applicable where, at the request of Focal on behalf of
               its customers, USWC constructs a greater quantity of facilities
               than that which USWC would otherwise construct or normally
               utilize.

               (deleted)USWC Proposed Paragraph:(deleted)

                                    Page 55
<PAGE>
 
               (deleted)8. Nonrecurring charges will be billed at the applicable
               Tariff rates.

               MFS Proposed Paragraph:(deleted)

          8.   Nonrecurring charges will be billed at the applicable Tariff
               rates, less a wholesale discount of 11%, pending determination by
               the Commission in the generic cost proceeding of an appropriate
               wholesale discount, if any.7





          9.   As part of the resold line, USWC provides operator services,
               directory assistance, and IntraLATA long distance with standard
               USWC branding. At the request of Focal and where technically
               feasible USWC will rebrand operator services and directory
               assistance in Focal's name, provided the costs associated with
               such rebranding are paid by Focal. Focal will have the option of
               obtaining such services on an unbranded basis, at no additional
               cost for "unbranding" the service.

          10.  USWC will address all Focal requests for ancillary resale
               systems, programs, and initiatives on an individual case basis.

     F.   Directory Listings

          As part of each resold line, USWC will accept at no charge one primary
          listing for each main telephone number belonging to Focal's end user
          customer based on end user information provided to USWC by Focal. USWC
          will place Focal's listings in USWC's directory listing database for
          directory assistance purposes and will make listings available to
          directory publishers and to other third parties. Additional terms and
          conditions with respect to directory listings are described in Section
          XV, Directory Listings, herein..

     G.   Deposit

          1.   USWC may require Focal to make a suitable deposit to be held by
               USWC as a guarantee of the payment of charges. Any deposit
               required of an existing reseller is due and payable within ten
               days after the requirement is imposed. The amount of the deposit
               shall be the estimated charges for the resold service which will
               accrue for a two-month period. Interest on the deposit shall be
               accumulated by USWC at a rate equal to the federal discount rate,
               as published in the Wall Street Journal from time to time.

          2.   When the service is terminated, or when Focal has established
               satisfactory credit, the amount of the initial or additional
               deposit, with any interest due, will, at Focal's option, either
               be credited to Focal's account or refunded. Satisfactory credit
               for a reseller is defined as twelve consecutive months service as
               a reseller without a termination for

- ----------
(7) The Parties are unable to determine whether the Arbitrator determined
    whether wholesale discounts apply to nonrecurring charges. Without waiving
    their respective positions, the Parties have included this provision
    providing for an interim discount rate only.

                                    Page 56
<PAGE>
 
               nonpayment and with no more than one notification of intent to
               terminate Service for nonpayment.

H.   Payment

     1.   Amounts payable under this Agreement are due and payable within thirty
          (30) days after the date of USWC's invoice.

     2.   A late payment charge of 1.5% applies to all billed balances which are
          not paid by the billing date shown on the next bill. To the extent
          Focal pays the billed balance on time, but the amount of the billed
          balance is disputed by Focal, and, it is later determined that a
          refund is due Focal, interest shall be payable on the refunded amount
          in the amount of 1.5% per month.

     3.   USWC may discontinue processing orders for the failure by Focal to
          make full payment for the resold services provided under this
          Agreement within thirty (30) days of Focal's receipt of bill.

     4.   USWC may disconnect for the failure by Focal to make full payment for
          the resold services provided under this Agreement within sixty (60)
          days of Focal's receipt of bill.

     5.   Collection procedures and the requirements for deposit are unaffected
          by the application of a late payment charge.

     6.   In the event USWC terminates the provisioning of any resold services
          to Focal for any reason, Focal shall be responsible for providing any
          and all necessary notice to its end users of the termination. In no
          case shall USWC be responsible for providing such notice.

     (deleted)USWC Proposed Language:

     7.   USWC shall bill all amounts due from MFS for each resold service in
          accordance with the terms and conditions as specified in the USWC
          tariff.

     MFS Proposed Language(deleted)

     7.   USWC shall bill all amounts due from Focal for resold service within
          90 days.(8)

- ----------
(8) The proposed provision has been included pursuant to the Arbitrator's
    Decision in Docket UT-960323.

                                    Page 57

<PAGE>
 
XXXI. UNBUNDLED ACCESS/ELEMENTS

     A.   General Terms

          1.   USWC agrees to provide the following unbundled network elements
               which are addressed in more detail in later sections of this
               agreement: 1) local loop, 2) local and tandem switches (including
               all vertical switching features provided by such switches, 3)
               interoffice transmission facilities, 4) network interface
               devices, 5) signaling and call-related database facilities, 6)
               operations support systems functions, and 7) operator and
               directory assistance facilities.

          (deleted)USWC Proposed Paragraph:(deleted)

          2.   (deleted)(9)This Agreement provides for the provision of
               Unbundled Loops to MFS which may be connected with MFS's switch
               for the purpose of offering a finished retail service. In
               addition, USWC agrees to provide an Unbundled Switching Element
               to MFS pursuant to the NIUER Process which may be combined with
               MFS provided loops to provide a finished retail service. USWC
               will not combine USWC's Unbundled Loops with USWC's Unbundled
               Switching Element to provide a finished service to MFS. USWC
               agrees, however, to offer finished retail services to MFS for
               resale pursuant to Section XXX, Resale, of this
               Agreement.(deleted)

          3.   USWC will not restrict the types of telecommunications services
               Focal may offer through unbundled elements, nor will it restrict
               Focal from combining elements with any technically compatible
               equipment the Focal owns. USWC will provide Focal with all of the
               functionalities of a particular element, so that Focal can
               provide any telecommunications services that can be offered by
               means of the element. USWC agrees to perform and Focal agrees to
               pay for the functions necessary to combine requested elements in
               any technically feasible manner either with other elements from
               USWC's network, or with elements possessed by Focal. However,
               USWC need not combine network elements in any manner requested if
               not technically feasible, but must combine elements ordinarily
               combined in its network in the manner they are typically
               combined.

     B.   Description of Unbundled Elements

          1.   Tandem Switching

               USWC will provide a tandem switching element on an unbundled
               basis. The tandem switch element includes the facilities
               connecting the trunk distribution frames to the switch, and all
               the functions of the switch itself,

- ----------
(9) The proposed USWC paragraph has been deleted pursuant to the Arbitrator's
    Decision in Docket UT 960323.

                                    Page 58
<PAGE>
 
               including those facilities that establish a temporary
               transmission path between two other switches. The definition of
               the tandem switching element also includes the functions that are
               centralized in tandems rather than in separate end office
               switches, such as call recording, the routing of calls to
               operator services, and signaling conversion functions.

          2.   Transport

               USWC will provide unbundled access to shared transmission
               facilities between end offices and the tandem switch. Further,
               USWC will provide unbundled access to dedicated transmission
               facilities between its central offices or between such offices
               and those of competing carriers. This includes, at a minimum,
               interoffice facilities between end offices and serving wire
               centers (SWCs), SWCs and IXC POPs, tandem switches and SWCs, end
               offices or tandems of USWC , and the wire centers of USWC and
               requesting carriers. USWC will also provide all technically
               feasible transmission capabilities, such as DS1, D53, and Optical
               Carrier levels (e.g. OC-311 2/48/96) that Focal could use to
               provide telecommunications services.

          3.   Digital Cross Connect System.

               USWC will provide Focal with access to mutually agreed upon
               digital cross-connect system (DCS) points.

          4.   Unbundled Loops

               a.   Service Description

                    i.   An Unbundled Loop establishes a transmission path
                         between the USWC distribution frame (or equivalent) up
                         to, and including, USWC's network interface device
                         (NID). For existing loops, the inside wire connection
                         to the NID will remain intact.

                    ii.  Basic Unbundled Loops are available as a two-wire or
                         four-wire, point-to-point configuration suitable for
                         local exchange type services within the analog voice
                         frequency range of 300 to 3000 Hz. For the two-wire
                         configuration, Focal is requested to specify loop
                         start, ground start or loop reverse battery options.
                         The actual loop facilities that provide this service
                         may utilize various technologies or combinations of
                         technologies. Basic Unbundled Loops provide an analog
                         facility to Focal.

                         (a)  To the extent Focal requires an Unbundled Loop to
                              provide ISDN, HDSL, ADSL or DS1 service, such
                              requirements will be identified on the order for
                              Unbundled Loop Service. Conditioning charges will

                                    Page 59
<PAGE>
 
                              apply, as required, to condition such loops to
                              ensure the necessary transmission standard.(10)

                         (b)  Specific channel performance options for the loops
                              can be ordered by identifying the Network Channel
                              (NC)/Network Channel Interface (NCI) for the
                              functions desired. USWC will provide Focal with
                              the available NC/NCI codes and their descriptions.

               b.   Unbundled Loops are provided in accordance with the
                    specifications, interfaces and parameters described in the
                    appropriate Technical Reference Publications. USWC's sole
                    obligation is to provide and maintain Unbundled Loops in
                    accordance with such specifications, interfaces and
                    parameters. USWC does not warrant that Unbundled Loops are
                    compatible with any specific facilities or equipment or can
                    be used for any particular purpose or service. Transmission
                    characteristics may vary depending on the distance between
                    Focal's end user and USWC's end office and may vary due to
                    characteristics inherent in the physical network. USWC, in
                    order to properly maintain and modernize the network, may
                    make necessary modifications and changes to the network
                    elements in its network on an as needed basis. Such changes
                    may result in minor changes to transmission parameters.
                    Changes that affect network interoperability require advance
                    notice pursuant to Section XIX, Notice of Changes, herein.

               c.   Facilities and lines furnished by USWC on the premises of
                    Focal's end user and up to the NID or equivalent are the
                    property of USWC. USWC must have access to all such
                    facilities for network management purposes. USWC's employees
                    and agents may enter said premises at any reasonable hour to
                    test and inspect such facilities and lines in connection
                    with such purposes or upon termination or cancellation of
                    the Unbundled Loop Service to remove such facilities and
                    lines. The Parties agree to explore issues surrounding the
                    extension of Unbundled Loops beyond the NID.

               d.   Unbundled Loops include the facilities between the USWC
                    distribution frame up to and including USWC's NID located at
                    Focal's end user premise. The connection between the
                    distribution frame and Focal facilities is accomplished via
                    channel

- ----------
(10) Conditioning charges were addressed at Page 11/12 of the Arbitrator's
     Decision in Docket UT-960323. The Parties have agreed to this footnote in
     order to implement Paragraph XXXI.B.4.a.ii.(a). The appropriate charges
     will be determined in the consolidated cost proceeding. Pending such
     determination. USWC will not assess conditioning charges for deloading or
     the removal of excessive bridge tans on Unbundled Loops which are less than
     12.000 feet in length.

                                    Page 60
<PAGE>
 
                    terminations that can be ordered in conjunction with either
                    Collocation or Unbundled Interoffice Transport Service.

               e.   Ordering and Maintenance.

                    i.   For the purposes of loop assignment, tracking, and
                         dispute resolution, USWC will require a Letter of
                         Authorization for each existing USWC end user for which
                         Focal has requested reassignment of the loop serving
                         that end user.

                    ii.  If there is a conflict between an end user (and/or its
                         respective agent) and Focal regarding the disconnection
                         or provision of Unbundled Loops, USWC will honor the
                         latest dated Letter of Authorization designating an
                         agent by the end user or its respective agent. If the
                         end user's service has not been disconnected and
                         Unbundled Loop Service is not yet established, Focal
                         will be responsible to pay the nonrecurring charge as
                         set forth herein. If the end user's service has been
                         disconnected and the end user's service is to be
                         restored with USWC, Focal will be responsible to pay
                         the applicable nonrecurring charges as set forth in
                         USWC's applicable tariff, to restore the end user's
                         prior service with USWC.

                    iii. Focal is responsible for its own end user base and will
                         have the responsibility for resolution of any service
                         trouble report(s) from its customers. USWC will work
                         cooperatively with Focal to resolve trouble reports
                         when the trouble condition has been isolated and found
                         to be within a portion of USWC's network. Focal must
                         provide to USWC switch-based test results when testing
                         its customer's trouble prior to USWC performing any
                         repair functions. The Parties will cooperate in
                         developing mutually acceptable test report standards.
                         USWC shall provide Focal with Maintenance of service
                         charges in accordance with applicable time and material
                         charges in USWC tariffs will apply when the trouble is
                         not in USWC's network.

                    iv.  Focal will be responsible to submit to USWC a
                         disconnect order for a Unbundled Loop that is
                         relinquished by the end user due to cessation of
                         service. Unbundled Loop facilities will be returned to
                         USWC when the disconnect order is complete. In the
                         event of transfer of the end user's service from one
                         provider to another, the new provider will issue a
                         request for transfer of service, resulting in the
                         appropriate disconnect/reconnection of service.

                                    Page 61
<PAGE>
 
                    v.   The installation due date is a negotiated item. For
                         related orders, new connects will be physically worked
                         within the same calendar day.

                    vi.  When ordering Unbundled Loops, Focal is responsible for
                         obtaining or providing facilities and equipment that
                         are compatible with the service.

                    vii. Focal will have responsibility for testing the
                         equipment, network facilities and the Unbundled Loop
                         facility. If USWC performs tests of the Unbundled Loop
                         facility at Focal's request, and the fault is not in
                         the USWC facilities, a charge shall apply.

                   viii. Focal will be responsible for providing battery and
                         dial tone to its connection point two days prior to the
                         due date on the service order.

                    ix.  The following procedures shall apply to Unbundled Loops
                         ordered with the option of Basic Testing at Coordinated
                         Time:

                         (a)  On each Unbundled Loop order, Focal and USWC will
                              agree on a cutover time at least 48 hours before
                              that cutover time. The cutover time will be
                              defined as a 30 minute window within which both
                              the Focal and USWC personnel will make telephone
                              contact to complete the cutover.

                         (b)  Within the appointed 30 minute cutover time, the
                              Focal person will call the USWC person designated
                              to perform cross-connection work and when the USWC
                              person is reached in that interval such work will
                              be promptly performed. If the Focal person fails
                              to call or is not ready within the appointed
                              interval, and if Focal had not called to
                              reschedule the work at least 2 hours prior to the
                              start of the interval, USWC and Focal will
                              reschedule the work order and Focal will pay the
                              non-recurring charge for the Unbundled Loops
                              scheduled for the missed appointment. In addition,
                              non-recurring charges for the rescheduled
                              appointment will apply. If the USWC person is not
                              available or not ready at any time during the 30
                              minute interval, Focal and USWC will reschedule
                              and USWC will waive the non-recurring charge for
                              the Unbundled Loops scheduled for that interval.
                              The standard time expected from disconnection of
                              service on a line to the connection of the
                              Unbundled Loop to the Focal

                                    Page 62
<PAGE>
 
                              Collocation Service is 5 minutes. If USWC causes a
                              line to be out of service due solely to its
                              failure for more than 15 minutes, USWC will waive
                              the nonrecurring charge for that Unbundled Loop.
                              If unusual or unexpected circumstances prolong or
                              extend the time required to accomplish the
                              coordinated cut-over, the Party responsible for
                              such circumstances is responsible for the
                              reasonable labor charges of the other Party.
                              Delays caused by the customer are the
                              responsibility of Focal. In addition, if Focal has
                              ordered INP as a part of the Unbundled Loop
                              installation, USWC will coordinate implementation
                              of INP with the Unbundled Loop installation;
                              provided, separate INP installation charges will
                              apply.

                    x.   Focal and USWC will work cooperatively to develop
                         forecasts for Unbundled Loop service. USWC requests an
                         eighteen month forecast of Unbundled Loop service. The
                         forecast will include the specific serving Wire Center
                         that will be requested, plus the specific quantity of
                         each service desired. The forecast will be updated
                         quarterly, and will be treated as Focal confidential
                         information.

               f.   Appendix A contains the rate information for Unbundled
                    Loops.

               g.   If applicable, the New Interconnection/Unbundled Element
                    Request Process will apply as detailed in Section XXIII of
                    this Agreement.

               (deleted)USWC Proposed Paragraph:(deleted)

               h.   For issues regarding If applicable, Construction Charges,
                    see Section XXIX of this Agreement. (deleted)pursuant to
                    Section XXIX, of this Agreement, may apply to the
                    construction of new Unbundled Loops on behalf of
                    MFS.(deleted)

          5.   Local Switching Elements

               The switching network element includes facilities that are
               associated with the line (e.g., the line card), facilities that
               are involved with switching the call, and facilities used for
               custom routing. USWC will provide the local switching element to
               Focal pursuant to the Network Interconnection/Unbundled Element
               Request Process described in Section XXIII herein.

                                    Page 63
<PAGE>
 
          6.   Network Interface Device (NID)

               a.   Service Description.

                    A device wired between a telephone protector and the inside
                    wiring to isolate the customer's equipment from the network
                    at the subscriber's premises. It is a device for the
                    termination of inside wire that is available in single and
                    multiple pair configurations.

               b.   Focal may connect its loops, via its own NID, to the USWC
                    NID.

               c.   Any costs associated with Focal connecting its NID to USWC's
                    NID, will be the responsibility of Focal.

               d.   Connecting Focal's loop directly to the USWC NID is
                    prohibited.

               e.   If Focal purchases an unbundled loop, Focal may provide its
                    own NID or have USWC provide the NID.

               f.   The price for access to the NID will be provided on a
                    case-by-case basis.

          7.   Additional Unbundled Elements

               USWC shall provide nondiscriminatory access to, and where
               appropriate, development of additional unbundled network elements
               not covered in this Agreement in response to specific requests
               therefor, pursuant to the New Interconnection/Unbundled Element
               Request Process detailed in Section XXIII of this Agreement.

XXXII. SERVICE STANDARDS

     A.   Definitions

          When used in this Section, the following terms shall have the meanings
          indicated.

          1.   "Specified Performance Commitment" means the commitment by USWC
               to meet the Performance Criteria for any Specified Activity
               during the Specified Review Period.

          2.   "Specified Activity" means any of the following activities:

               a.   The installation by USWC of Unbundled Loops for Focal
                    ("Unbundled Loop Installation");

               b.   USWC's provision of Interim Number Portability ("INP
                    Installation") to Focal;

                                    Page 64
<PAGE>
 
               c.   The repair of USWC service provided to Focal ("Out of
                    Service Repairs"); or

               d.   The installation by USWC of interconnection trunks for the
                    mutual exchange of local exchange traffic with Focal ("LIS
                    Trunk Installation")
   
          3.   "Performance Criteria" means, with respect to a Specified Review
               Period (i.e., a calendar month or quarter), the performance by
               USWC for the specified activities for Focal will meet or exceed
               the average performance by USWC for the total universe of
               specified performance.  

     B.   Failure to Meet the Performance Criteria. If during a Specified Review
          Period USWC fails to meet the performance criteria, USWC will use its
          best efforts to meet the Performance Criteria for the next Specified
          Review Period. If USWC fails to meet the performance criteria for two
          consecutive periods, the Parties agree, in good faith, to attempt to
          resolve such issues through negotiation or non-binding arbitration.
          This paragraph shall not be construed to waive either Party's right to
          seek legal or regulatory intervention as provided by state or federal
          law. Focal may seek regulatory or other legal relief including
          requests for specific performance of USWC's obligations under this
          Agreement.

     C.   Limitations. USWC's failure to meet or exceed and of the Performance
          Criteria can not be as a result, directly or indirectly, of a Delaying
          Event. A "Delaying Event" means (a) a failure by Focal to perform any
          of its obligations set forth in this Agreement, (b) any delay, act or
          failure to act by a Customer, agent of subcontractor of Focal or (C)
          any Force Majeure Event. If a Delaying Event prevents USWC from
          performing a Specified Activity, then such Specified Activity shall be
          excluded from the calculation of USWC's compliance with the
          Performance Criteria.

     D.   Records. USWC shall maintain complete and accurate records, for the
          Specified Review Period of its performance under this Agreement for
          each Specified Activity and its compliance with the Performance
          Criteria. USWC shall provide to Focal such records in a self-reporting
          format. The parties agree that such records shall be deemed
          "Proprietary Information".

XXXIII. IMPLEMENTATION SCHEDULE

     A.   Within 3 months from the date of final approval of this Agreement, the
          Parties agree to make a good faith effort to complete each of the
          following interconnection arrangements:

          1.   Two-way trunk groups, as listed in Section VI, Paragraph G(2)
               herein, necessary for the mutual exchange of traffic.

          2.   E-911 Trunking and database access;

          3.   SS7 Interconnection and Certification;
 
                                    Page 65
<PAGE>
    
          4.   Directory Listings Arrangements and Directory Assistance
               Interconnection;

          5.   Access to Unbundled Loops in at least one wire center;

          6.   Completion of Physical Collocation arrangements in at least one
               USWC wire center.

          7.   Completion of inter-carrier billing arrangements necessary for
               the joint provision of switched access services and for
               reciprocal traffic exchange.

     B.   The Parties have agreed to commence discussion of these and other
          implementation issues by May 1, 1997 to facilitate the above
          implementation schedule.

XXXIV. MISCELLANEOUS TERMS

     A.   General Provisions

          1.   Each Party shall use its best efforts to comply with the
               Implementation Schedule.

          2.   Each Party is individually responsible to provide facilities
               within its network which are necessary for routing, transporting,
               measuring, and billing traffic from the other Party's network and
               for delivering such traffic to the other Party's network in the
               standard format compatible with Focal's network and to terminate
               the traffic it receives in that standard format or the proper
               address on its network. Such facility shall be designed based
               upon the description and forecasts provided under this Agreement.
               The Parties are each solely responsible for participation in and
               compliance with national network plans, including the National
               Network Security Plan and the Emergency Preparedness Plan.

          3.   Neither Party shall use any service related to or use any of the
               services provided in this Agreement in any manner that interferes
               with other persons in the use of their service, prevents other
               persons from using their service, or otherwise impairs the
               quality of service to other carriers or to either Party's
               Customers, and each Party may discontinue or refuse service if
               the other Party violates this provision Upon such violation,
               either Party shall provide the other Party notice of such
               violation, if practicable, at the earliest practicable time.

          4.   Each Party is solely responsible for the services it provides to
               its Customers and to other Telecommunications Carriers.

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<PAGE>
 
          5.   The parties shall work cooperatively to minimize fraud associated
               with third-number billed calls, calling card calls, and any other
               services related to this Agreement.

     B.   Most Favored Nation Terms and Treatment

          The parties agree that the provisions of Section 252(i) of the Act
          shall apply, including state and federal interpretive regulations in
          effect from time to time.

     C.   Letter of Authorization

          Where so indicated in specific sections of this Agreement, Focal is
          responsible to have a Letter of Authorization. Focal is solely
          responsible to obtain authorization from its end user for the handling
          of the disconnection of the end user's service with USWC, the
          provision of service by Focal, and the provision of Unbundled Loops
          and all other ancillary services. Should a dispute or discrepancy
          arise regarding the authority of Focal to act on behalf of the end
          user, Focal is responsible for providing written evidence of its
          authority to USWC.

     D.   Payment

          1.   Amounts payable under this Agreement are due and payable within
               thirty (30) days after the date of invoice.

          2.   Unless otherwise specified, any amount due and not paid by the
               due date stated above shall be subject to a late charge equal to
               either i) 0.03 percent per day compounded daily for the number of
               calendar days from the payment due date to and including, the
               date of payment, that would result in an annual percentage rate
               of 12% or ii) the highest lawful rate, whichever is less. If late
               payment charges for services are not permitted by local
               jurisdiction, this provision shall not apply.

     E.   Taxes

          Each party purchasing services hereunder shall pay or otherwise be
          responsible for all federal, state, or local sales, use, excise, gross
          receipts, transaction or similar taxes, fees or surcharges levied
          against or upon such purchasing Party (or the providing Party when
          such providing Party is permitted to pass along to the purchasing
          Party such taxes, fees or surcharges), except for any tax on either
          Party's corporate existence, status or income. Whenever possible,
          these amounts shall be billed as a separate item on the invoice. To
          the extent a sale is claimed to be for resale tax exemption, the
          purchasing Party shall furnish the providing Party a proper resale tax
          exemption certificate as authorized or required by statute or
          regulation by the jurisdiction providing said resale tax exemption.
          Failure to timely provide said resale tax exemption certificate will
          result in no exemption being available to the purchasing Party.

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     F.   Intellectual Property

          1.   Each Party hereby grants to the other Party the limited, personal
               and nonexclusive right and license to use its patents, copyrights
               and trade secrets but only to the extent necessary to implement
               this Agreement or specifically required by the then applicable
               federal and state rules and regulations relating to
               interconnection and access to telecommunications facilities and
               services, and for no other purposes. Nothing in this Agreement
               shall be construed as the grant to the other Party of any rights
               or licenses to trademarks.

          2.   The rights and licenses under Section F. 1. above are granted "AS
               IS" and the other Party's exercise of any such right and license
               shall be at the sole and exclusive risk of the other Party.
               Neither Party shall have any obligation to defend, indemnify or
               hold harmless, or acquire any license or right for the benefit
               of, or owe any other obligation or have any liability to, the
               other based on or arising from any claim, demand, or proceeding
               (hereinafter "claim") by any third party alleging or asserting
               that the use of any circuit, apparatus, or system, or the use of
               any software, or the performance of any service or method, or the
               provision of any facilities by either Party under this Agreement
               constitutes infringement, or misuse or misappropriation of any
               patent, copyright, trade secret, or any other proprietary or
               intellectual property right of any third party.

          3.   Focal shall not, without the express written permission of USWC,
               state or imply that; 1) Focal is connected, or in any way
               affiliated with USWC or its affiliates, 2) Focal is part of a
               joint business association or any similar arrangement with USWC
               or its affiliates, 3) USWC and its affiliates are in any way
               sponsoring, endorsing or certifying Focal and its goods and
               services, or 4) with respect to Focal advertising or promotional
               activities or materials, that the resold goods and services are
               in any way associated with or originated from USWC or any of its
               affiliates. Nothing in this paragraph shall prevent Focal from
               truthfully describing the network elements it uses to provide
               service to its customers.

     G.   Severability

          The Parties recognize that the FCC is promulgating rules addressing
          issues contained in this Agreement. In the event that any one or more
          of the provisions contained herein shall for any reason be held to be
          unenforceable in any respect under law or regulation, the parties will
          negotiate in good faith for replacement language. If replacement
          language cannot be agreed upon, either party may seek regulatory
          intervention, including negotiations pursuant to Sections 251 and 252
          of the Act.

                                    Page 68
<PAGE>
 
     H.   Responsibility for Environmental Contamination

          Neither Party shall be liable to the other for any costs whatsoever
          resulting from the presence or Release of any Environmental Hazard
          that either Party did not introduce to the affected Work Location.
          Both Parties shall defend and hold harmless the other, its officers,
          directors and employees from and against any losses, damages, claims,
          demands, suits, liabilities, fines, penalties and expenses (including
          reasonable attorneys' fees) that arise out of or result from (i) any
          Environmental Hazard that the indemnifying party, its contractors or
          agents introduce to the Work Locations or (ii) the presence or Release
          of any Environmental Hazard for which the indemnifying party is
          responsible under Applicable Law.

     I.   Responsibility of Each Party

          Each Party is an independent contractor, and has and hereby retains
          the right to exercise full control of and supervision over its own
          performance of its obligations under this Agreement and retains full
          control over the employment, direction, compensation and discharge of
          all employees assisting in the performance of such obligations. Each
          Party will be solely responsible for all matters relating to payment
          of such employees, including compliance with social security taxes,
          withholding taxes and all other regulations governing such matters.
          Each Party will be solely responsible for proper handling, storage,
          transport and disposal at its own expense of all (i) substances or
          materials that it or its contractors or agents bring to, create or
          assume control over at work locations or, (ii) waste resulting
          therefrom or otherwise generated in connection with its or its
          contractors' or agents' activities at the work locations. Subject to
          the limitations on liability and except as otherwise provided in this
          Agreement, each Party shall be responsible for (i) its own acts and
          performance of all obligations imposed by applicable law in connection
          with its activities, legal status and property, real or personal and,
          (ii) the acts of its own affiliates, employees, agents and contractors
          during the performance of that Party's obligations hereunder.

     J.   Referenced Documents

          All references to Sections, Exhibits, and Schedules shall be deemed to
          be references to Sections of, and Exhibits and Schedules to, this
          Agreement unless the context shall otherwise require. Whenever any
          provision of this Agreement refers to a technical reference, technical
          publication, Focal practice, USWC practice, any publication of
          telecommunications industry administrative or technical standards, or
          any other document specifically incorporated into this agreement, it
          will be deemed to be a reference to the most recent version or edition
          (including any amendments, supplements, addenda, or successors) or
          such document that is in effect, and will include the most recent
          version or edition (including any amendments, supplements, addenda, or
          successors) or each document incorporated by reference in such a
          technical reference, technical publication, Focal practice, USWC
          practice, or publication of industry standards (unless Focal elects
          otherwise). Should there by any inconsistency

                                    Page 69
<PAGE>
 
          between or among publications or standards, Focal shall elect which
          requirement shall apply.

     K.   Publicity and Advertising

          Neither party shall publish or use any advertising, sales promotions
          or other publicity materials that use the other party's logo,
          trademarks or service marks without the prior written approval of the
          other party.

     L.   Executed in Counterparts

          This Agreement may be executed in any number of counterparts, each of
          which shall be deemed an original; but such counterparts shall
          together constitute one and the same instrument.

     M.   Headings of No Force or Effect

          The headings of Articles and Sections of this Agreement are for
          convenience of reference only, and shall in no way define, modify or
          restrict the meaning or interpretation of the terms or provisions of
          this Agreement.

     N.   Entire Agreement

          This Agreement constitutes the entire agreement between the Parties
          and supersedes all prior oral or written agreements, representations,
          statements, negotiations, understandings, proposals and undertakings
          with respect to the subject matter hereof.

     O.   Joint Work Product

          This Agreement is the joint work product of the Parties and has been
          negotiated by the Parties and their respective counsel and shall be
          fairly interpreted in accordance with its terms and, in the event of
          any ambiguities, no inferences shall be drawn against either Party.

     P.   Disclaimer of Agency

          Except for provisions herein expressly authorizing a Party to act for
          another, nothing in this Agreement shall constitute a Party as a legal
          representative or agent of the other Party, nor shall a Party have the
          right or authority to assume, create or incur any liability or any
          obligation of any kind, express or implied, against or in the name or
          on behalf of the other Party unless otherwise expressly permitted by
          such other Party Except as otherwise expressly provided in this
          Agreement, no Party undertakes to perform any obligation of the other
          Party whether regulatory or contractual, or to assume any
          responsibility for the management of the other Party's business.

                                    Page 70
<PAGE>
 
     Q.   Survival

          The Parties' obligations under this Agreement which by their nature
          are intended to continue beyond the termination or expiration of this
          Agreement shall survive the termination or expiration of this
          Agreement.

     R.   Effective Date

          This Agreement shall become effective pursuant to Sections 251 and 252
          of the Act.

     S.   Amendment of Agreement

          Focal and USWC may mutually agree to amend this Agreement in writing.
          Since it is possible that amendments to this Agreement may be needed
          to fully satisfy the purposes and objectives of this Agreement, the
          Parties agree to work cooperatively, promptly and in good faith to
          negotiate and implement any such additions, changes and corrections to
          this Agreement.

     T.   Indemnity

          1.   Each of the Parties agrees to release, indemnify, defend and hold
               harmless the other Party and each of its officers, directors,
               employees and agents (each an "Indemnitee") from and against and
               in respect of any loss, debt, liability, damage, obligation,
               claim, demand, judgment or settlement of any nature or kind,
               known or unknown, liquidated or unliquidated including, but not
               limited to, costs and attorneys' fees, whether suffered, made,
               instituted, or asserted by any other party or person, for
               invasion of privacy, personal injury to or death of any person or
               persons, or for loss, damage to, or destruction of property,
               whether or not owned by others, resulting from the indemnifying
               Party's performance, breach of Applicable Law, or status of its
               employees, agents and subcontractors; or for failure to perform
               under this Agreement, regardless of the form of action.

          2.   The indemnification provided herein shall be conditioned upon:

               a.   The indemnified Party shall promptly notify the indemnifying
                    Party of any action taken against the indemnified Party
                    relating to the indemnification. Failure to so notify the
                    Indemnifying Party shall not relieve the Indemnifying Party
                    of any liability that the Indemnifying Party might have,
                    except to the extent that such failure prejudices the
                    Indemnifying Party's ability to defend such claim.

               b.   The indemnifying Party shall have sole authority to defend
                    any such action, including the selection of legal counsel,
                    and the

                                    Page 71
<PAGE>
 
                    indemnified Party may engage separate legal counsel only at
                    its sole cost and expense.

               c.   In no event shall the indemnifying Party settle or consent
                    to any judgment pertaining to any such action without the
                    prior written consent of the indemnified Party.

     U.   Limitation of Liability

          1.   Except as otherwise provided in the indemnity section, no Party
               shall be liable to the other Party for any Loss, defect or
               equipment failure caused by the conduct of the other Party, the
               other Party's agents, servants, contractors or others acting in
               aid or concert with the other Party.

          2.   Except for Losses alleged or made by a Customer of either Party,
               in the case of any Loss arising from the negligence or willful
               misconduct of both Parties, each Party shall bear, and its
               obligations under this Section shall be limited to, that portion
               (as mutually agreed to by the Parties) of the resulting expense
               caused by its (including that of its agents, servants,
               contractors or others acting in aid or concert with it)
               negligence or willful misconduct.

          3.   Except for indemnity obligations, each Party's liability to the
               other Party for any Loss relating to or arising out of any
               negligent act or omission in its performance of this Agreement,
               whether in contract or in tort, shall be limited to the total
               amount that is or would have been charged to the other Party by
               such negligent or breaching Party for the service(s) or
               function(s) not performed or improperly performed.

          4.   In no event shall either Party have any liability whatsoever to
               the other Party for any indirect, special, consequential,
               incidental or punitive damages, including but not limited to loss
               of anticipated profits or revenue or other economic loss in
               connection with or arising from anything said, omitted or done
               hereunder (collectively, "Consequential Damages"), even if the
               other Party has been advised of the possibility of such damages;
               provided, that the foregoing shall not limit a Party's obligation
               to indemnify, defend and hold the other Party harmless against
               any amounts payable to a third party, including any losses,
               costs, fines, penalties, criminal or civil judgments or
               settlements, expenses (including attorneys' fees) and
               Consequential Damages of such third party. Nothing contained in
               this section shall limit either Party's liability to the other
               for (I) willful or intentional misconduct (including gross
               negligence); (ii) bodily injury, death or damage to tangible real
               or tangible personal property proximately caused by such party's
               negligent act or omission or that of their respective agents,
               subcontractors or employees nor shall anything contained in this
               section limit the Parties' indemnification obligations, as
               specified below.

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<PAGE>
 
     V.   Terms of Agreement

          This Agreement shall be effective upon Commission Approval and shall
          remain in effect through July 7, 1999, and thereafter the Agreement
          shall continue in force and effect unless and until a new agreement,
          addressing all of the terms of this Agreement, becomes effective
          between the Parties. The Parties agree to commence negotiations on a
          new agreement no later than two years after this Agreement becomes
          effective.

     W.   Controlling Law

          This Agreement was negotiated by the Parties in accordance with the
          terms of the Act and the laws of the state where service is provided
          hereunder. It shall be interpreted solely in accordance with the terms
          of the Act and the applicable state law in the state where the service
          is provided.

     X.   Cancellation Charges

          Except as provided pursuant to a Network Element Network
          Interconnection and Unbundled Element Request, or as otherwise
          provided in any applicable tariff or contract referenced herein, no
          cancellation charges shall apply.

     Y.   Regulatory Approval

          The Parties understand and agree that this Agreement will be filed
          with the Commission and may thereafter be filed with the FCC. In the
          event the Commission rejects any portion of this Agreement, the
          parties agree to meet and negotiate in good faith to arrive at a
          mutually acceptable modification to the rejected portion.

     Z.   Compliance

          Each party shall comply with all applicable federal, state, and local
          laws, rules and regulations applicable to its performance under this
          Agreement.

     AA.  Compliance with the Communications Law Enforcement Act of 1994
          ("CALEA")

          Each Party represents and warrants that any equipment, facilities or
          services provided to the other Party under this Agreement comply with
          CALEA. Each party shall indemnify and hold the other Party harmless
          from any and all penalties imposed upon the other Party for such
          noncompliance and shall at the non-compliant Party's sole cost and
          expense, modify or replace any equipment, facilities or services
          provided to the other Party under this Agreement to ensure that such
          equipment, facilities and services fully comply with CALEA.

                                    Page 73
<PAGE>
 
     BB.  Independent Contractor

          Each party shall perform services hereunder as an independent
          contractor and nothing herein shall be construed as creating any other
          relationship between the Parties. Each party and each Party's
          contractor shall be solely responsible for the withholding or payment
          of all applicable federal, state and local income taxes, social
          security taxes and other payroll taxes with respect to their
          employees, as well as any taxes, contributions or other obligations
          imposed by applicable state unemployment or workers' compensation
          acts. Each party has sole authority and responsibility to hire, fire
          and otherwise control its employees.

     CC.  Force Majeure

          Neither party shall be liable for any delay or failure in performance
          of any part of this Agreement from any cause beyond its control and
          without its fault or negligence including, without limitation, acts of
          nature, acts of civil or military authority, government regulations,
          embargoes, epidemics, terrorist acts, riots, insurrections, fires,
          explosions, earthquakes, nuclear accidents, floods, work stoppages,
          equipment failure, power blackouts, volcanic action, other major
          environmental disturbances, unusually sever weather conditions,
          inability to secure products or services of other persons or
          transportation facilities or acts or omissions of transportation
          carriers (collectively, a "Force Majeure Event") In the event of a
          labor dispute or strike the Parties agree to provide service to each
          other at a level equivalent to the level they provide themselves.

     DD.  Dispute Resolution

          The Parties agree, in good faith, to attempt to resolve any claim,
          controversy or dispute between the Parties, their agents, employees,
          officers, directors or affiliated agents ("Dispute") through
          negotiation or non-binding arbitration. This paragraph shall not be
          construed to waive the Parties' rights to seek legal or regulatory
          intervention as provided by state or federal law.

     EE.  Commission Decision

          This Agreement shall at all times be subject to such review by the
          Commission or FCC as permitted by the Act. If any such review renders
          the Agreement inoperable or creates any ambiguity or requirement for
          further amendment to the Agreement, the Parties will negotiate in good
          faith to agree upon any necessary amendments to the Agreement.

     FF.  Nondisclosure

          1.   All information, including but not limited to specifications,
               microfilm, photocopies, magnetic disks, magnetic tapes, drawings,
               sketches, models, samples, tools, technical information, data,
               employee records, maps, financial reports, and market data, (i)
               furnished by one Party to the other Party dealing with customer
               specific, facility specific, or usage

                                    Page 74
<PAGE>
 
               specific information, other than customer information
               communicated for the purpose of publication of directory database
               inclusion, or (ii) in written, graphic, electromagnetic, or other
               tangible form and marked at the time of delivery as
               "Confidential" or "Proprietary", or (iii) communicated orally and
               declared to the receiving Party at the time of delivery, or by
               written notice given to the receiving Party within ten (10) days
               after delivery, to be "Confidential" or "Proprietary"
               (collectively referred to as "Proprietary Information"), shall
               remain the property of the disclosing Party. A Party who receives
               Proprietary Information via an oral communication may request
               written confirmation that the material is Proprietary
               Information. A Party who delivers Proprietary Information via an
               oral communication may request written confirmation that the
               Party receiving the information understands that the material is
               Proprietary Information.

          2.   Upon request by the disclosing Party, the receiving Party shall
               return all tangible copies of Proprietary Information, whether
               written, graphic or otherwise, except that the receiving Party
               may retain one copy for archival purposes.

          3.   Each Party shall keep all of the other Party's Proprietary
               Information confidential and shall use the other Party's
               Proprietary Information only in connection with this Agreement.
               Neither Party shall use the other Party's Proprietary Information
               for any other purpose except upon such terms and conditions as
               may be agreed upon between the Parties in writing.

          4.   Unless otherwise agreed, the obligations of confidentiality and
               non-use set forth in this Agreement do not apply to such
               Proprietary Information as:

               a.   was at the time of receipt already known to the receiving
                    Party free of any obligation to keep it confidential
                    evidenced by written records prepared prior to delivery by
                    the disclosing Party; or

               b.   is or becomes publicly known through no wrongful act of the
                    receiving Party; or

               c.   is rightfully received from a third person having no direct
                    or indirect secrecy or confidentiality obligation to the
                    disclosing Party with respect to such information; or

               d.   is independently developed by an employee, agent, or
                    contractor of the receiving Party which individual is not
                    involved in any manner with the provision of services
                    pursuant to the Agreement and does not have any direct or
                    indirect access to the Proprietary Information; or

               e.   is disclosed to a third person by the disclosing Party
                    without similar restrictions on such third person's rights;
                    or

                                    Page 75
<PAGE>
 
               f.   is approved for release by written authorization of the
                    disclosing Party; or

               g.   is required to be made public by the receiving Party
                    pursuant to applicable law or regulation provided that the
                    receiving Party shall give sufficient notice of the
                    requirement to the disclosing Party to enable the disclosing
                    Party to seek protective orders.

          5.   Effective Date of This Section. Notwithstanding any other
               provision of this Agreement, the Proprietary Information
               provisions of this Agreement shall apply to all information
               furnished by either Party to the other in furtherance of the
               purpose of this Agreement, even if furnished before the date of
               this Agreement.

     GG.  Notices

          Any notices required by or concerning this Agreement shall be sent to
          the Parties at the addresses shown below:

               USWC 
               Director Interconnection Services
               1801 California, Room 2340
               Denver, CO 80202

               Focal Communications Corporation of Washington
               Director, Regulatory Affairs (fax 312-895-8403)
               200 N. LaSalle Street, Suite 800
               Chicago, Illinois 60601

          Each Party shall inform the other of any changes in the above
          addresses.

     HH.  Assignment

          Neither Party may assign or transfer (whether by operation of law or
          otherwise) this Agreement (or any rights or obligations hereunder) to
          a third party without the prior written consent of the other Party
          provided that each Party may assign this Agreement to a corporate
          affiliate or an entity under its common control or an entity acquiring
          all or substantially all of its assets or equity by providing prior
          written notice to the other Party of such assignment or transfer. Any
          attempted assignment or transfer that is not permitted is void ab
          initio. Without limiting the generality of the foregoing, this
          Agreement shall be binding upon and shall inure to the benefit of the
          Parties' respective successors and assigns.

     II.  Warranties

          NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE PARTIES
          AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE

                                    Page 76
<PAGE>
 
          DOES NOT EXIST, ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT
          LIMITED TO WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
          PURPOSE.

     JJ.  Default

          If either Party defaults in the payment of any amount due hereunder,
          or if either Party violates any other provision of this Agreement, and
          such default or violation shall continue for thirty (30) days after
          written notice thereof, the other Party may seek legal and/or
          regulatory relief. The failure of either Party to enforce any of the
          provisions of this Agreement or the waiver thereof in any instance
          shall not be construed as a general waiver or relinquishment on its
          part of any such provision, but the same shall, nevertheless, be and
          remain in full force and effect.

     KK.  No Third Party Beneficiaries

          Except as may be specifically set forth in this Agreement, this
          Agreement does not provide and shall not be construed to provide third
          parties with any remedy, claim, liability, reimbursement, cause of
          action, or other privilege.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed
by their respective duly authorized representatives.






Focal Communications                        U S WEST Communications, Inc.
Corporation of Washington

John R Barnicle (on file)                   Katherine L. Fleming (on file)**
- ----------------------------------          ----------------------------------
Signature                                   Signature

John R Barnicle                             Katherine L. Fleming
- ----------------------------------          ----------------------------------
Name Printed/Typed                          Name Printed/Typed

                                            Executive Director Interconnect
EVP & C.O.O                                 Neg.
- ----------------------------------          ----------------------------------
Title                                       Title

1/18/99                                     1/21/99
- ----------------------------------          ----------------------------------
Date                                        Date


*        This Agreement is made pursuant to Section 252 (i) of the Act and is
premised upon the Interconnection Agreement between Electric Lightwave, Inc. and
U S WEST Communications, Inc. (the "Underlying Agreement"). The Underlying
Agreement was approved by the Commission on April 23, 1997.

                                    Page 77
<PAGE>
 
With respect to this agreement, the Parties understand and agree:


i) The Parties shall request the Commission to expedite its review and approval
of this Agreement.

ii) Notwithstanding the mutual commitments set forth herein, the Parties are
entering into this Agreement without prejudice to any positions they have taken
previously, or may take in the future, in any legislative, regulatory, or other
public forum addressing any matters, including those relating to the types of
arrangements contained in this Agreement. During the proceeding in which the
Commission is to review and approve the Agreement, U S WEST may point out that
it has objected, and continues to object, to the inclusion of the terms and
conditions to which it objected in the proceedings involving the approval of the
Underlying Agreement.

iii) This Agreement contains provisions based upon the decisions and orders of
the FCC and the Commission under and with respect to the Act. Currently, court
and regulatory proceedings affecting the subject matter of this Agreement are in
various stages, including the proceedings where certain of the rules and
regulations of the FCC are being challenged (see Iowa Utilities Board v. Federal
Communications Commission. 120 F.3d 753 (8th Cir. 1997), et sec.) and the
proceedings where the Commission's decision(s) giving rise to the Underlying
Agreement are under and subject to appeal and review (the "Proceedings"). The
Agreement has not been corrected to reflect the requirements, claims or outcomes
of any of the Proceedings, although the pricing does reflect the Commission's
most current generic order, if any. Accordingly, when a final, decision or
decisions are made in the Proceedings that automatically change and modify the
Underlying Agreement, then like changes and modifications will similarly be made
to this Agreement.

iv) Subsequent to the execution of this Agreement, the FCC or the Commission may
issue decisions or orders that change or modify the rules and regulations
governing implementing of the Act. If such changes or modifications alter the
state of the law upon which the Underlying Agreement was negotiated and agreed,
and it reasonably appears that the parties to the Underlying Agreement would
have negotiated and agreed to different term(s) condition(s) or covenant(s) than
as contained in the Underlying Agreement had such change or modification been in
existence before execution of the Underlying Agreement, then this Agreement
shall be amended to reflect such different terms(s), condition(s), or
covenant(s). Where the parties fail to agree upon such an amendment, it shall be
resolved in accordance with the Dispute Resolution provision of this Agreement.

**   Signature does not indicate agreement with all aspects of the arbitrator's
     decision, nor does it waive any of U S WEST's rights to seek judicial
     review of all or part of the agreement, or to reform the agreement as the
     result of successful judicial review.


                                    Page 78
<PAGE>
 
                         APPENDIX A - RATES AND CHARGES

                                   Washington

INTERCONNECTION - LOCAL EXCHANGE

Local Call Termination                                      Agreed Price
     End Office - Per Minute of Use                         $0.003141
     Tandem Switch - Per Minute of Use                      $0.005416
     (Note 1)
     (includes End Office Call Termination and Tandem Transport)

Note 1: The above local tandem call termination rate includes tandem
transmission based on an assumed transport mileage of 10 miles.
Should the average tandem transmission mileage experienced by the Parties exceed
10 miles, the Parties agree to adjust the tandem call termination rate based on
the tandem transmission rates set forth below.

                                             Agreed Price   Agreed Price
Entrance Facility                            Recurring      Nonrecurring
DS1, Electrical                              $99.78         $583.92
DS3, Electrical                              $404.24        $668.95

Direct Trunked Transport                     Agreed Price   Agreed Price
                                             Fixed          Per Mile
DS1 - 0 Miles                                None           None
DS1 - Over 0 to 8                            $41.72         $0.67
DS1 - Over 8 to 25                           $41.72         $0.84
DS 1 -  Over 25 to 50                        $41.73         $2.97
DS1 - Over 50                                $41.73         $3.49

DS3 - 0 miles                                None           None
DS3 - Over 0 to 8                            $283.30        $13.83
DS3 - Over 8 to 25                           $284.17        $15.03
DS3 - Over 25 to 50                          $291.31        $39.19
DS3 - Over 50                                $293.91        $44.74

                                             Agreed Price   Agreed Price
Multiplexing, per arrangement                Recurring      Nonrecurring
DS3 to DS1                                   $218.58        $418.45

Local Transit Traffic Rate                   Agreed Price
Tandem Switching, per MOU                    $0.001794

                                             Agreed Price   Agreed Price
Tandem Transmission                          Fixed          Per Mile
0 Mile                                       None           None
Over 0 to 8 miles                            $0.000411      $0.000009
Over 8 to 25 miles                           $0.000411      $0.000007
Over 25 to 50                                $0.000408      $0.000008
Over 50                                      $0.000409      $0.000015

                                    Page 79
<PAGE>
 
INTERCONNECTION 0xf0 EXCHANGE ACCESS         Agreed Price

Call Termination, Transport, and Transit     Per Switched Access Tariff


COMMON CHANNEL SIGNALLING ACCESS SERVICE

                                             Agreed Price   Agreed Price
Entrance Facility                            Recurring      Nonrecurring
DS1                                          $99.78         $563.92
DS3                                          $404.24        $668.95

                                             Agreed Price   Agreed Price
Direct Link Transport                        Fixed          Per Mile
DSO - 0 Mile                                 None           None
DSO - Over 0 to 8 miles                      $ 20.89        $0.13
DSO - Over 8 to 25 miles                     $ 20.88        $0.10
DSO - Over 25 to 50                          $ 20.88        $0.10
DSO - Over 50                                $ 20.89        $0.17

DS1 - 0 Mile                                 None           None
DS1 - Over 0 to 8 miles                      $41.72         $0.67
DS1 - Over 8 to 25 miles                     $41.72         $0.84
DS1 - Over 25 to 50                          $41.73         $2.97
DS1 - Over 50                                $41.73         $3.49

                                             Agreed Price   Agreed Price
Direct Link Transport                        Fixed          Per Mile
DS3 - 0 Mile                                 None           None
DS3 - Over 0 to 8 miles                      $283.30        $13.83
DS3 - Over 8 to 25 miles                     $284.17        $15.03
DS3 - Over 25 to 50                          $291.31        $39.19
DS3 - Over 50                                $293.91        $44.74

                                             Agreed Price   Agreed Price
                                             Recurring      Nonrecurring
CCS Link - First Link                        None           $504.68
CCS Link - Each additional  Link             None           $72.42
STP Port - Per Port                          $208.57        None

                                             Agreed Price   Agreed Price
                                             Recurring      Nonrecurring
Multiplexing
DS1 to DS0                                   $221.08        None
DS3 to DS1                                   $218.58        None

                                    Page 80
<PAGE>
 
PHYSICAL AND VIRTUAL COLLOCATION

                                                  Arbitrated Price
Common Elements                              Recurring      Nonrecurring

Quote Preparation Fee                        None           $2437.30

Entrance Facility - Per cable (Note 3)       $2.07          $1307.45
2-wire DSO EICT                              $1.41          $339.61 (Note 4)
4-wire DSO EICT                              $1.79          $339.61 (Note 4)
DSI EICT                                     $9.12          $405.02
DS3 EICT                                     $31.93         $433.23
DSI EICT - regeneration       (Note 5)       $14.38
DS3 EICT - regeneration       (Note 5)       $94.24

Cable Splicing                               Agreed Price   Agreed Price
                                             Recurring      Nonrecurring
Per set up                                   None           $103.59
Per fiber Spliced                            None           $12.95
48 Volt Power, per ampere per month          $13.45         None
48 Volt Power Cable
20 Ampere Capacity - recurring               $0.15          $68.37
40 Ampere Capacity - recurring               $0.20          $92.71
60 Ampere Capacity - recurring               $0.22          $104.42

Equipment Bay, per shelf                     $8.58          None

                                             Agreed Price   Agreed Price
                                             Regular Hours  After Hours
Inspector per 1/2 Hour                       $28.62         $37.02
Training per 1/2 hour                        $25.36         None
Engineering per 1/2 hour                     $24.73         $33.09
Installation per 1/2 hour                    $28.62         $37.20
Maintenance per 1/2 hour                     $25.36         $33.73

                                             Agreed Price   Agreed Price
                                             Recurring      Nonrecurring
PHYSICAL COLLOCATION (Note 6)
Cage/Hard Wall Enclosure                       ICB          ICB
Rent (w/Maintenance) per square foot -Zone 1   $2.75        None
Rent (w/Maintenance) per square foot -Zone 2   $2.26        None
Rent (w/Maintenance) per square foot -Zone 3   $2.06        None


Note 3: Pricing is pursuant to Arbitrator's Decision in Docket UT-960323.

Note 4: same as note 3 above, and, DS0 EICT NRC does not apply to unbundled
loops where a separate unbundled loop NRC applies.

                                    Page 81
<PAGE>
 
Note 5: If required. No NRC to regeneration ordered concurrently with an
associated EICT element.

Note 6: Zones per NECA-4 Tariff

ANCILLARY SERVICES

                                              Agreed Price
Directory Assistance
Price per Call -- Facilities-Based Providers  $0.34

Listings
Primary Listings, Directory Assistance,
White Pages                                  No charge

E911
LEC and Focal recover costs from PSAP        No charge


                                             Agreed Cost
                                             Recurring
Interim Number Portability
Without Transport
Per Number Ported - First Path               $4.25
Per Number Ported - Additional Path          $3.02

With Transport
Per Number Ported - First Path               $8.73
Per Number Ported - Additional Path          $7.50


                                             Agreed Cost
                                             Nonrecurring
Additional charges
Service Establishment, per switch, per
Route                                        $43.80
Service Establishment - additional number
ported or changes to existing numbers,
per number ported                            $9.49

Additional and Consecutive Numbers --
additional number ported on same
account name and consecutive numbers,
per number ported                            $7.05

                                             Agreed Price
Assignment of Numbers
Assignments per industry guidelines          No charges

Busy Line Verification
Per Call                                     $0.72

Busy Line Interrupt
Per Call                                     $0.87

                                    Page 82
<PAGE>
 
                                                  Arbitrated Price
                                             Recurring         Nonrecurring

Unbundled Loops (Note 7)
State-wide per loop                          $13.37



Without testing, first loop per service order                  $96.30
With Basic Testing, first loop per service order               $153.86
With Basic Testing at Designated Time, first loop per          $206.02
service order

Without testing, additional loop per service order             $20.00
With Basic Testing, additional loop per service order          $30.00
With Basic Testing at Designated Time, additional loop         $30.00
per service order

Note 7: Price of unbundled Loops and additional Loops is ordered pursuant to
Arbitrators Decision in Docket UT-960323



                                    Page 83
<PAGE>
 
                                   APPENDIX A


                           COMMISSION IMPOSED RESALE
                                WHOLESALE RATES
                                   WASHINGTON

U S WEST need not make the following services available for Resale:
          Enhanced services including Voice Mail
U S WEST shall make the following services available for Resale:
          All telecommunications services.

U S WEST shall make all services, except Switched Access, Special Access, and
Residence Exchange services, available for Resale at a 21% discount rate, as
ordered by the Commission (i.e. Wholesale price is 79% of Retail price, where
Retail is the offered tariff price). Where USWC offers services under a volume
discount, Focal may purchase such services at the volume discount rate or the
21% Resale discount rate, whichever provides a greater discount.


                                    Page 84
<PAGE>
 
                                   APPENDIX A

                                     RESALE
                              NONRECURRING CHARGES
                                   WASHINGTON


Description                             Arbitrated Price

Customer Transfer Charge
      Business, per end user            $56.60
      Residence, per end user           $54.13
      ISDN, per end user                $57.15


                                    Page 85
<PAGE>
 
                     APPENDIX B - ENGINEERING REQUIREMENTS
                              TRUNK FORECAST FORMS

                           INTERCONNECTION CHECKLIST
                                   MEET POINT

DATE OF MEETING:
Interconnector Information

Name
- ------------------------------------------------------------------------------
Address
- ------------------------------------------------------------------------------
City, State, Zip:
- ------------------------------------------------------------------------------
Technical Contact Person:
- ------------------------------------------------------------------------------
Technical Contact Person Telephone #:
- ------------------------------------------------------------------------------
USWC Negotiator:
- ------------------------------------------------------------------------------
USWC Negotiator Telephone #:
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
Desired U S WEST Central office
- ------------------------------------------------------------------------------
CLLI
- ------------------------------------------------------------------------------
Central office address:
- ------------------------------------------------------------------------------
City, State:
- ------------------------------------------------------------------------------
Meet Point Address:
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------

Equipment
- ------------------------------------------------------------------------------
Manufacture/ model #                    Quantity
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------

Cable Makeup
- ------------------------------------------------------------------------------
Number of cables:
- ------------------------------------------------------------------------------
Number of fibers per cable:
- ------------------------------------------------------------------------------
Distance from USWC to Meet Point
- ------------------------------------------------------------------------------
Distance from Focal to Meet Point
- ------------------------------------------------------------------------------
Service Requirements

                              Year 1         Year 2         Year 3
- ------------------------------------------------------------------------------
DS3
- ------------------------------------------------------------------------------
DS1
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
Remarks:

Please attach a sketch of the requested meet point arrangement:

                                    Page 86
<PAGE>
 
                              Appendix B - PAGE 2
                           INTERCONNECTION CHECKLIST
                              ADDITIONAL TRUNKING

Interconnector Information

Name:
- ------------------------------------------------------------------------------
Address:
- ------------------------------------------------------------------------------
City, State, Zip:
- ------------------------------------------------------------------------------
Technical Contact Person:
- ------------------------------------------------------------------------------
Technical Contact Person Telephone #:
- ------------------------------------------------------------------------------
USWC Negotiator:
- ------------------------------------------------------------------------------
USWC Negotiator Telephone #:
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
Desired Central office (TANDEM) 
- ------------------------------------------------------------------------------
CLLI:
- ------------------------------------------------------------------------------
Central office address:
- ------------------------------------------------------------------------------
City, State:
- ------------------------------------------------------------------------------
Meet Point Address:
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------

Service Requirements
                                        Year 1         Year 2         Year 3
- ------------------------------------------------------------------------------
USWC End Office:
- ------------------------------------------------------------------------------
- - Terminating CCS (peak busy hr)
- ------------------------------------------------------------------------------
- - Number Portability:
- ------------------------------------------------------------------------------
     Arrangements
- ------------------------------------------------------------------------------
     Call paths per # ported
- ------------------------------------------------------------------------------
USWC End Office:
- ------------------------------------------------------------------------------
- - Terminating COS (peak busy hr)
- ------------------------------------------------------------------------------
- - Number Portability:
- ------------------------------------------------------------------------------
     Arrangements
- ------------------------------------------------------------------------------
     Call paths per # ported
- ------------------------------------------------------------------------------
USWC End Office:
- ------------------------------------------------------------------------------
- - Terminating CCS (peak busy hr)
- ------------------------------------------------------------------------------
- - Number Portability:
- ------------------------------------------------------------------------------
     Arrangements
- ------------------------------------------------------------------------------
     Call paths per # ported
- ------------------------------------------------------------------------------
USWC End Office:
- ------------------------------------------------------------------------------
- - Terminating CCS (peak busy hr)
- ------------------------------------------------------------------------------
- - Number Portability:
- ------------------------------------------------------------------------------
     Arrangements
- ------------------------------------------------------------------------------
     Call paths per # ported
- ------------------------------------------------------------------------------
Remarks:

Please attach a sketch of the agreed upon meet point arrangement

                                    Page 87
<PAGE>
 
                  APPENDIX C - PHYSICAL COLLOCATION AGREEMENT



                                    BETWEEN



                             US WEST COMMUNICATIONS


                                      AND


                 FOCAL COMMUNICATIONS CORPORATION OF WASHINGTON
<PAGE>
 
TABLE OF ARTICLES
ARTICLE I - PREMISES                                                  -1-
ARTICLE II - EFFECTIVENESS AND REGULATORY APPROVAL                    -2-
ARTICLE Ill - TERM                                                    -4-
ARTICLE IV -  PREMISES CHARGES                                        -4-
ARTICLE V - INTERCONNECTION CHARGES                                   -8-
ARTICLE VI - DEMARCATION POINT                                        -8-
ARTICLE VII - USE OF PREMISES                                         -8-
ARTICLE VIII - STANDARDS                                              -10-
ARTICLE IX - RESPONSIBILITIES OF THE INTERCONNECTOR AND US WEST       -11-
ARTICLE X - QUIET ENJOYMENT                                           -14-
ARTICLE XI - ASSIGNMENT                                               -14-
ARTICLE XII - CASUALTY LOSS                                           -14-
ARTICLE XIII - LIMITATION OF LIABILITY                                -16-
ARTICLE XIV - SERVICES, UTILITIES, MAINTENANCE AND FACILITIES         -17-
ARTICLE XV - DISPUTE RESOLUTION                                       -17-
ARTICLE XVI - SUCCESSORS BOUND                                        -17-
ARTICLE XVII - CONFLICT OF INTEREST                                   -18-
ARTICLE XVIII - NON-EXCLUSIVE REMEDIES                                -18-
ARTICLE XIX - NOTICES                                                 -18-
ARTICLE XX - COMPLIANCE WITH LAWS                                     -19-
ARTICLE XXI - INSURANCE                                               -19-
ARTICLE XXII - US WEST'S RIGHT OF ACCESS                              -20-
ARTICLE XXIII - OTHER COLLOCATION AGREEMENTS                          -21-
ARTICLE XXIV - MISCELLANEOUS                                          -21-

                                     Page 2
<PAGE>
 
                         PHYSICAL COLLOCATION AGREEMENT

     THIS PHYSICAL COLLOCATION AGREEMENT ("Agreement") is made this _____day of
_______________19___ by and between U S WEST COMMUNICATIONS, a Colorado
corporation ("USWC"), and FOCAL COMMUNICATIONS CORPORATION OF WASHINGTON, a
Delaware corporation, its successors and assigns ("Interconnector").

                                   WITNESSETH

     WHEREAS, USWC is an incumbent local exchange carrier having a statutory
duty to provide for "physical collocation" of "equipment necessary for
interconnection or access to unbundled network elements at its Premises, U.S.C.
251 (c)(6); and

     WHEREAS, the Interconnector wishes to physically locate certain of its
equipment within the Premises (as defined herein) and connect with USWC; and

     NOW THEREFORE, in consideration of the mutual agreements and covenants
contained herein and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, USWC and the Interconnector (the
"parties") agree as follows:

     ARTICLE I - PREMISES

         1.1 Right to Use. Subject to this Agreement, USWC grants to
Interconnector the right to use the premises described on Exhibit C
("Premises"), attached and incorporated herein, within real property at
__________________________in the City of _______________County of
_________________ State of ______________.

         1.2 Relocation. Notwithstanding Section 1.1, in the event that it is
necessary for the Premises to be moved within the structure in which the
Premises is located ("Physical Collocation Site") or to another USWC Physical
Collocation Site, at the Interconnector's option, the Interconnector shall move
its facilities to the new Premises. The Interconnector shall be responsible for
the preparation of the new Premises if such relocation arises from circumstances
beyond the reasonable control of USWC, including condemnation or government
order or regulation that makes the continued occupancy of the Premises or
Physical Collocation Site impossible. Otherwise USWC shall be responsible for
any such preparation and shall bear all costs associated with the relocation.

         If the Interconnector requests that the Premises be moved within the
Physical Collocation Site or to another USWC Physical Collocation Site, USWC
shall permit the Interconnector to relocate the Premises, subject to
availability of space and associated requirements. The Interconnector shall be
responsible for all applicable charges associated with the move, including the
reinstallation of its equipment and facilities and the preparation of the new
Premises.

         In either such event, the new Premises shall be deemed the "Premises"
hereunder and the new Physical Collocation Site (where applicable) the "Physical
Collocation Site."

                                     Page 3
<PAGE>
 
         1.3 The Premises. USWC agrees, at the Interconnector's sole cost and
expense as set forth herein, to prepare the Premises in accordance with working
drawings and specifications entitled ____________________________ and dated
__________________ which documents, marked Exhibit C, are attached and
incorporated herein. The preparation shall be arranged by USWC in compliance
with all applicable codes, ordinances, resolutions, regulations and laws. In
return for the Interconnector's agreement to make the payments required by
Section 2.1 hereof, USWC agrees to pursue diligently the preparation of the
Premises for use by the Interconnector.

         ARTICLE II- EFFECTIVENESS AND REGULATORY APPROVAL

         2.1 Submission to State Commission. The Agreement is prepared as a
component of the Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996, between USWC and Focal Communications
Corporation of Washington ("Interconnection Agreement"), and the parties intend
to submit the Agreement and other elements of the Interconnection Agreement to
state commissions for approval under the provisions of 47 U.S.C. 0xf5 252. This
Agreement is conditioned upon the approval of this Agreement and the
Interconnection Agreement. After execution of this Agreement, the parties shall
submit it and the applicable Interconnection Agreement to the State commission
in the State in which the Premises is located for approval, and shall defend the
Agreement and support any reasonable effort to have this Agreement so approved,
including the supplying of witnesses and testimony if a hearing is held.

         2.2 Failure to Receive Approval. If this Agreement does not receive
such unqualified approval, this Agreement shall be void upon written notice of
either party to the other after such regulatory action becomes final and
unappealable. Thereafter Interconnector may request to begin negotiations again
under 47 U.S.C. 251. Alternatively, the parties may both agree to modify this
Agreement to receive such approval, but neither shall be required to agree to
any modification. Any agreement to modify shall not waive the right of either
party to pursue any appeal of the ruling made by any reviewing regulatory
commission or to seek arbitration of any of the terms of this Agreement or any
of the terms of the Interconnection Agreement.

         2.3 Preparation Prior to Regulatory Approval. At the written election
of the Interconnector, USWC shall begin preparing the Premises for the
Interconnector prior to receiving the approval required by Section 2.1 hereof.
Except as specified in the Interconnection Agreement, the evidence of such
election shall be the delivery to USWC of a letter requesting that USWC begin
preparations, payment of 50 percent of the non-recurring charge for preparing
the Premises for use by Focal, and the promise of Focal to pay the balance of
the non-recurring charges as provided in this Agreement. Payment to USWC of the
remaining non-recurring charges due under this Agreement shall be due one month
after the Interconnector's equipment is installed at the Premises,
interconnected with USWC and operational as described in Section 3.2 below. Upon
such an election, this Agreement shall become effective but only insofar as to
be applicable to Premises preparation. If the Agreement does not become fully
effective as contemplated by this Article due in any part to USWC not fulfilling
its obligation under 2.1 preceding, the Interconnector shall be entitled to a
refund of all payments made to USWC for preparation.

                                    Page 91
<PAGE>
 
         ARTICLE III  - TERM

         3.1 Commencement Date. This Agreement shall be a term agreement,
beginning on the "Commencement Date" and ending on a date five years afterwards.
The "Commencement Date" shall be the first day after the Interconnector's
equipment becomes operational as described in Section 3.2. At the end of the
term and unless the parties agree to an extension or a superseding arrangement,
this Agreement shall automatically convert to a month-to-month Agreement.

         3.2 Occupancy. Unless there are unusual circumstances, USWC will notify
the Interconnector that the Premises is ready for occupancy within five (5) days
after USWC completes preparations described in Section 2.3 The Interconnector
must place operational telecommunications equipment in the Premises and connect
with USWC's network within one hundred fifty (150) days after receipt of such
notice; provided, however, that such one hundred fifty day period shall not
begin until regulatory approval is obtained under Article II and, further, that
USWC may extend beyond the one hundred fifty days upon a demonstration by the
Interconnector of a best efforts to meet that deadline and circumstances beyond
its reasonable control that prevented the Interconnector from meeting that
deadline. If the Interconnector fails to do so, this Agreement is terminated on
the thirtieth (30 ) day after USWC provides to the Interconnector written notice
of such failure and the Interconnector does not place operational
telecommunications equipment in the Premises and connect with USWC's network by
such thirtieth day. In any such event, the Interconnector shall be liable in an
amount equal to the unpaid balance of the preparation charges due. For purposes
of this Section, the Interconnector's telecommunications equipment is considered
to be operational and interconnected when connected to USWC's network for the
purpose of providing service.

         ARTICLE IV - PREMISES CHARGES

         4.1 Monthly Charges. Beginning on the Commencement Date, Interconnector
shall pay to USWC monthly fees as specified in Exhibit A.

         4.2 Billing. Billing for Monthly Charges shall occur on or about the
25th day of each month, with payment due thirty (30) days from the bill date.
USWC may change its billing date practices upon providing ninety (90) days
written notice to the Interconnector. Each USWC bill must identify the Premises
location by CLLI and/or address and must separately identify any non-contiguous
Premises within the Physical Collocation Site. Further, USWC must specify
separately for each Premises CLLI and/or address and for any non-contiguous
Premises each rate element individually along with the quantity purchased by the
Interconnector at that (those) Premises and the individual rate charged for each
element along with the dates for which such charges apply. USWC shall promptly
adjust Interconnector's account in each instance of misbilling identified and
demonstrated by the Interconnector.

         4.3 Nonrecurring Charges.

               (a)  The one-time charge for preparing the Premises for use by
                    the Interconnector as well as all other one-time charges
                    associated with the Interconnector's request shall be
                    exactly as stated in Exhibit B.

                                    Page 5
<PAGE>
 
               (b)  USWC will contract for and perform the procurement,
                    construction and preparation activities underlying the
                    Monthly Fees and Nonrecurring Charges, using the same or
                    consistent practices that are used by USWC for other
                    construction and preparation work performed in the Physical
                    Collocation Site and shall make every possible effort to
                    obtain all necessary approvals and permits, where
                    applicable, promptly. USWC will obtain more than one trade
                    subcontractor submission to the extent available when the
                    initial trade subcontractor bid, proposal or quotation
                    associated with an ICB pursuant to Exhibit B exceeds
                    ten-thousand dollars ($10,000.00). It is understood and
                    agreed that any such request for additional subcontractor
                    submissions will likely add to the time necessary to provide
                    physical collocation and, for that reason, Interconnector
                    reserves the right to authorize USWC to forgo such
                    additional bids but will only do so in writing. USWC will
                    permit the Interconnector to inspect all supporting
                    documents for the Monthly Fees and Nonrecurring Charges. Any
                    dispute regarding such USWC charges will be subject to the
                    dispute resolution provisions hereof. Notwithstanding the
                    above, the Interconnector may directly contract with any
                    supplier, vendor, subcontractor, or contractor that USWC
                    approves for such work (including but not limited to the
                    procurement and installation of cages) and may, at
                    Interconnector's election, be solely responsible for any and
                    all payments due to such supplier, vendor, subcontractor or
                    contractor for such procurement, construction and
                    preparation activities. Where Interconnector exercises this
                    right, Interconnector shall pay to USWC only those amounts
                    associated with labor hours of USWC personnel necessary for
                    such USWC personnel to observe and approve such work at the
                    Premises within the Physical Collocation Site.

               (c)  Nonrecurring Charges associated with the
                    point-of-termination bay shall be applied to the
                    Interconnector by USWC only where the Interconnector
                    requests in writing that USWC supply such
                    point-of-termination bay. Otherwise, the Interconnector
                    shall be responsible for purchasing such
                    point-of-termination bays and for arranging their
                    installation by a vendor, subcontractor or contractor
                    approved by USWC to perform such work.

         4.4 Preparation. USWC will begin preparation on execution of this
Agreement and upon receipt of written notice from Interconnector as described in
Section 2.3.

         4.5 Pre-Preparation Access. USWC shall permit the Interconnector to
have access to the Premises for the purpose of inspection once physical
collocation site preparation activities have begun. Interconnector agrees to
limit the number of such inspections to three per Premises except where such
inspection exposes a non-conformance with the Interconnector's requirements as
stated in its initial request or this Agreement.

         4.6 Breach Prior to Commencement Date. If the Interconnector materially
breaches this Agreement by purporting to terminate this Agreement after USWC has
begun preparation of the Premises then, in addition to any other remedies that
USWC might have, the Interconnector shall be liable in the amount equal to the
non-recoverable costs less estimated net salvage. Non-recoverable costs include
the non-recoverable cost of equipment and material ordered, provided or used;
subcontractor charges paid by USWC for work performed

                                    Page 6
<PAGE>
 
on behalf of Interconnector; the non-recoverable cost of installation and
removal, including the costs of equipment and material ordered, provided and
used; labor for work done on behalf of Interconnector for preparation;
transportation and any other associated costs. USWC shall provide Interconnector
with a detailed invoice showing the costs it incurred associated with
preparation. Further, at the Interconnector's election, USWC shall provide to
the Interconnector all materials that it determined to be unsalvageable. Should
the costs incurred by USWC be used for the provision of a collocation
arrangement for a third party, such costs shall be refunded to the
Interconnector.

         4.7 Space Preparation Fee True-Up. For all work performed by USWC and
by vendors, subcontractors and contractors hired by USWC in order to prepare the
Premises pursuant to the Interconnector's written request and pursuant to 4.3
preceding, USWC shall within ninety (90) days of the completion of the Premises
preparation work perform a true-up of all USWC, vendor, subcontractor and
contractor bill amounts associated with any ICB pricing performed pursuant to
Exhibit B. If the resulting total cost is less than that paid by the
Interconnector, then USWC shall within thirty (30) days refund to the
Interconnector the difference between the actual cost and the payment that the
Interconnector had previously submitted to USWC. Alternatively, if the total
cost exceeds that previously paid by the Interconnector, then the Interconnector
shall submit payment to USWC for the difference within thirty (30) days for its
receipt of the bill for such an amount. Nothing in either case releases USWC
from its obligation to make best-faith efforts to achieve the lowest-available
cost for the preparation work that it proves is necessary or releases USWC from
its obligation to allow the Interconnector to inspect such documents pursuant to
4.3 preceding.

         ARTICLE V - INTERCONNECTION CHARGES

         Charges for interconnection and collocation shall be set forth in
Exhibits A and B.

         ARTICLE VI - DEMARCATION POINT

         6.1 Cable Entrances. The Interconnector shall use a dielectric fiber
optic cable as a transmission medium to the Premises, or other transmission
media as it determines is necessary in order to provide services for which it
has legal and regulatory authority. The Interconnector shall be permitted at
least two (2) cable entrance routes into the Premises whenever two entrance
routes are used by USWC at that Physical Collocation Site.

         6.2 Demarcation Point. USWC and the Interconnector shall designate the
point(s) of interconnection within the Physical Collocation Site as the point(s)
of physical demarcation between the Interconnector's network and USWC's network,
with each being responsible for maintenance and other ownership obligations and
responsibilities on its side of that demarcation point. USWC and the
Interconnector anticipate that the demarcation point will be within the
point-of-termination bay which the Interconnector may elect to provide and
install pursuant to 4.3 preceding. Where no point of termination bay is elected
by the Interconnector, the point(s) of interconnection shall be specified in
Exhibit D.


                                    Page 7
<PAGE>
 
         ARTICLE VII - USE OF PREMISES


         7.1 Nature of Use. The Premises are to be used by the Interconnector
for purposes of locating equipment and facilities within USWC's Physical
Collocation Sites to connect with USWC services or facilities and other
Interconnectors. USWC shall permit Interconnector to place, maintain and operate
on Premises any equipment, pursuant to the FCC's regulations on the types of
equipment required to be collocated. Consistent with the nature of the Premises
and the environment of the Premises, the Interconnector shall not use the
Premises for office, retail, or sales purposes. No signs or marking of any kind
by the Interconnector shall be permitted on the Premises or on the grounds
surrounding the Premises.

         7.2 Administrative Uses. The Interconnector may use the Premises for
placement of equipment and facilities only. The Interconnector's employees,
agents and contractors shall be permitted access to the Premises at all
reasonable times, provided that the Interconnector's employees, agent and
contractors comply with USWC's policies and practices pertaining to fire, safety
and security. The Interconnector agrees to comply promptly with all laws,
ordinances and regulations affecting the use of the Premises. Upon the
expiration of the Agreement, the Interconnector shall surrender the Premises to
USWC in the same condition as when first occupied by the Interconnector except
for ordinary wear and tear.

         7.3 Threat to Network or Facilities. Interconnector equipment or
operating practices representing a significant demonstrable technical threat to
USWC's network or facilities, including the Premises, are strictly prohibited.

         7.4 Interference or Impairment. Notwithstanding any other provision
hereof, the characteristics and methods of operation of any equipment or
facilities placed in the Premises shall not interfere with or impair service
over any facilities of USWC or the facilities of any other person or entity
located in the Physical Collocation Site; create hazards for or cause damage to
those facilities, the Premises, or the Physical Collocation Site; impair the
privacy of any communications carried in, from, or through the Physical
Collocation Site; or create hazards or cause physical harm to any individual or
the public. Any of the foregoing events would be a material breach of this
Agreement if, after USWC's submission to Interconnector of written notice of
such interference or impairment, Interconnector did not promptly work to
eliminate the interference or impairment.

         7.5 Interconnection to Others. The Interconnector may directly connect
to other Interconnectors' facilities within the Physical Collocation Site. USWC
agrees to provide to Interconnector, upon its receipt of the Interconnector's
written request, any facilities necessary for such interconnection wherever such
facilities exist or can be made available and USWC shall provide any such
facilities pursuant to 4.3 preceding and Exhibits A and B. Further, USWC agrees
to provide to the Interconnector, upon its receipt of the Interconnector's
written request, unbundled network transmission elements at rates specified in
Exhibits A and B, and USWC will facilitate interconnection of the
Interconnector's collocation equipment to other services offered in USWC's
tariffs or other Agreements (e.g., Synchronous Service Transport service). For
the purposes of Interconnection to Others, where the other Interconnector's
Interconnection Agreement differs from this Agreement, the less restrictive
terms and conditions relating to such direct interconnection and the lower
charges identified in the two Agreements for such direct interconnection shall
apply to both Interconnectors for all


                                    Page 8
<PAGE>
 
Interconnection between those two Interconnectors. Interconnector agrees to
continue to pay to USWC all applicable Monthly Charges for space, power and for
all other interconnection circuits at the Premises.

         7.6 Personality and its Removal. Subject to the Article, the
Interconnector may place or install in or on the Premises such fixtures and
equipment as it shall deem desirable for the conduct of business. Personal
property, fixtures and equipment placed by the Interconnector in the Premises
shall not become a part of the Premises, even if nailed, screwed or otherwise
fastened to the Premises, but shall retain their status as personality and may
be removed by Interconnector at any time. Any damage caused to the Premises by
the removal of such property shall be promptly repaired by Interconnector at its
expense.

         7.7 Alterations In no case shall the Interconnector or any person
purporting to be acting through on or behalf of the Interconnector make any
rearrangement, modification, improvement, addition, repair, or other alteration
to the Premises or the Physical Collocation Site without the advance written
permission and direction of USWC. USWC shall make best efforts to honor any
reasonable request for a modification, improvement, addition, repair, or other
alteration proposed by the Interconnector, provided that USWC shall have the
right to, for reasons that it specifies in writing, reject or modify any such
request except as required by state or federal regulators. The cost of any such
specialized alterations shall be paid by Interconnector in accordance with the
terms and conditions identified in Article IV herein.

         ARTICLE VIII - STANDARDS

         8 Minimum Standards. This Agreement and the physical collocation
provided hereunder is made available subject to and in accordance with the (i)
Bellcore Network Equipment Premises System (NEBS) Generic Requirements
(GR-63-CORE and GR-1089-CORE), as may be amended at any time and from time to
time, and any successor documents, except to the extent that USWC deviates from
any such requirements for its equipment and the facilities and services that it
uses and provides or to the extent that USWC allows other Interconnectors to
deviate from any such requirements; and, (ii) any statutory and/or regulatory
requirements in effect at the execution of this Agreement or that subsequently
become effective and then when effective. The Interconnector shall strictly
observe and abide by each. USWC shall publish and provide to the Interconnector
its Reference Handbook for Collocation to provide Interconnector with guidelines
and USWC's standard operating practices for collocation. USWC agrees that the
material terms and conditions of collocation are not contained in such a
technical publication, nor can USWC change the terms and conditions of this
Agreement by changing that technical publication; however, any revision made to
address situations potentially harmful to USWC's network or the Premises or
Physical Collocation Site, or to comply with statutory and/or regulatory
requirements shall become effective immediately and the Interconnector agrees to
take steps to comply with such revisions immediately upon its receipt of USWC's
written notification of the change.

         ARTICLE IX - RESPONSIBILITIES OF THE INTERCONNECTOR AND USWC

         9.1 Contact Number. The Interconnector and USWC are responsible for
providing to each other personnel contact numbers for their respective technical
personnel who are readily accessible 24 hours a day, 7 days a week, 365 days a
year.

                                    Page 9
<PAGE>
 
         9.2 Trouble Status Reports. The Interconnector is responsible for
promptly providing trouble report status when requested by USWC. Likewise, USWC
is responsible for promptly providing trouble report status when requested by
Interconnector.

         9.3 Cable Extension. The Interconnector is responsible for bringing its
cable to entrance manhole(s) or other appropriate sites designated by USWC
(e.g., utility poles or controlled environmental vaults), and for leaving
sufficient cable length in order for USWC to fully extend the
Interconnector-provided cable to the Premises. In the alternative, at the
Interconnector's option, USWC shall provide interconnection facilities, i.e.,
unbundled network transmission elements, from an Interconnector-designated
location (e.g., the Interconnector's Node) to the Premises within the Physical
Collocation Site. Nothing in this paragraph shall preclude the Interconnector
from obtaining unbundled network transmission elements from USWC at any Premises
within a Physical Collocation Site for primary or redundant interconnection.

         9.4 Regeneration. Regeneration on intra-building connections will be
provided by USWC, when requested. The price for regeneration shall be pursuant
to Exhibit B.

         9.5 Removal. The Interconnector is responsible for removing any
equipment, property or other items that it brings into the Premises or any other
part of the Physical Collocation Site. If the Interconnector fails to remove any
equipment, property, or other items from the Premises or Physical Collocation
Site within thirty (30) days after discontinuance of use, USWC may perform the
removal and may charge the Interconnector for any materials used in any such
removal, and the time spent on such removal at the then-applicable hourly rate
for administrative work pursuant to the TA96 factor approach identified on
Exhibit B.

         9.6 Interconnector's Equipment and Facilities. The Interconnector is
solely responsible for the design, engineering, testing, performance, and
maintenance of the equipment and facilities used by the Interconnector in the
Premises. The Interconnector will be responsible for servicing, supplying,
repairing, installing and maintaining the following facilities within the
Premises:

         (a)   its cable(s);
         (b)   its equipment;
         (c)   required point of termination cross connects;
         (d)   point of termination maintenance, including replacement fuses and
               circuit breaker restoration, to the extent that such fuses and
               circuit breakers are not controlled by USWC and only if and as
               required; and
         (e)   the connection cable and associated equipment which may be
               required within the Premises to the point(s) of interconnection.
               USWC does not assume any such responsibility unless contracted to
               perform such work on behalf of the Interconnector.

         9.7 Verbal Notifications Required. The Interconnector is responsible
for immediate verbal notification to USWC of significant outages or operations
problems which could impact or degrade USWC's network, switches, or services,
and for providing an estimated clearing time for restoration. In addition,
written notification must be provided within twenty-four (24) hours. Likewise,
USWC is responsible for providing immediate verbal notification to the
Interconnector

                                    Page 10
<PAGE>
 
of problems with USWC's network or operations which could impact or degrade
Interconnector's network, switches, or services, and provide an estimated
clearing time for restoration. Further, USWC shall provide written notification
to Interconnector within the same twenty-four (24) hour interval. For the
purposes of this paragraph, written notification may be given by electronic mail
so long as the notifying party provide the required verbal notification to the
other.

         9.8 Service Coordination. The Interconnector is responsible for
coordinating with USWC to ensure that services are installed in accordance with
the service request. Likewise, USWC is obligated to coordinate with
Interconnector to ensure the services are installed in accordance with the
service request and fulfill the service request in a timely, effective manner.

         9.9 Testing. The Interconnector is responsible for testing, to identify
and clear a trouble when the trouble has been isolated to an
Interconnector-provided facility or piece of equipment. If USWC testing is also
required, it will be promptly provided as part of its obligation to provide to
Interconnector network interconnection.

         ARTICLE X - QUIET ENJOYMENT

         Subject to the other provisions hereof, USWC covenants that it has full
right and authority to permit the use of the Premises by the Interconnector and
that, so long as the Interconnector performs all of its obligations herein, the
Interconnector may peaceably and quietly enjoy the Premises during the term
hereof.

         ARTICLE XI - ASSIGNMENT

         The Interconnector shall not assign or otherwise transfer this
Agreement, neither in whole nor in part, or permit the use of any part of the
Premises by any other person or entity, without the prior written consent of
USWC. Any purported assignment or transfer made without such consent may be made
void by USWC at its option.

         ARTICLE XII - CASUALTY LOSS

         12.1 Damage to Premises. If the Premises are damaged by fire or other
casualty, and

          (i)  the Premises are not rendered untenantable in whole or in part,
               USWC shall repair the same at its expense (as hereafter limited)
               and the Monthly Charges shall not be abated, or

          (ii) the Premises are rendered untenantable in whole or in part and
               such damage or destruction can be repaired within ninety (90)
               days, USWC has the option to repair the Premises at its expense
               (as hereafter limited) and all Monthly Charges shall be
               proportionately abated while Interconnector was deprived of the
               use and the interconnection. If the Premises cannot be repaired
               within ninety (90) days, or USWC opts not to rebuild, then this
               Agreement shall (upon notice to the Interconnector within thirty
               (30) days following such occurrence) terminate as of the date of
               such damage. However, USWC must provide to Interconnector

                                    Page 11
<PAGE>
 
               comparable substitute interconnection and collocation
               arrangements at another mutually-agreeable Physical Collocation
               Site without penalty or nonrecurring charges assessed against the
               Interconnector.

Any obligation on the part of USWC to repair the Premises shall be limited to
repairing, restoring and rebuilding the Premises as originally prepared for the
Interconnector and shall not include any obligation to repair, restore, rebuild
or replace any alterations or improvements made by the Interconnector or by USWC
on request of the Interconnector; or any fixture or other equipment installed in
the Premises by the Interconnector or by USWC on request of the Interconnector.

         12.2 Damage to Premises. In the event that the Premises shall be so
damaged by fire or other casualty that closing, demolition or substantial
alteration or reconstruction thereof shall, in USWC's opinion, be advisable,
then, notwithstanding that the Premises may be unaffected thereby, USWC, at its
option, may terminate this Agreement by giving the Interconnector ten (10) days
prior written notice within thirty (30) days following the date of such
occurrence.

         ARTICLE XIII - LIMITATION OF LIABILITY

         14.1 Limitation. With respect to any claim or suit for damages arising
in connection with the mistakes, omissions, interruptions, delays or errors, or
defects in transmission occurring in the course of furnishing service hereunder,
the liability of USWC, if any shall be as described in the Interconnection
Agreement in effect between the parties.

         Each party shall be indemnified and held harmless by the other against
claims and damages by any third party arising from provision of the other
party's services or equipment except those claims and damages directly
associated with the provision of services to the other party which are governed
by the provisioning party's applicable tariffs. Neither party shall have any
liability whatsoever to the customers of the other party for claims arising from
the provision of the other party's service to its customers, including claims
for interruption of service, quality of service or billing disputes.

         The liability of either party for its willful misconduct, if any, is
not limited by this Agreement.

         14.2 Third Parties. The Interconnector acknowledges and understands
that USWC may provide space in or access to the Physical Collocation Site to
other persons or entities ("Others"), which may include competitors of the
Interconnector; that such space may be close to the Premises, possibly including
space adjacent to the Premises and/or with access to the outside of the
Premises; and that any in-place optional cage around the Premises is a permeable
boundary that will not prevent the Others from observing or even damaging the
Interconnector's equipment and facilities. In addition to any other applicable
limitation, USWC shall have no liability with respect to any action or omission
by any Other, except in instances involving negligence or willful actions by
USWC or its agents or employees. The Interconnector shall save and hold USWC
harmless from any and all costs, expenses, and claims associated with any such
acts or omission by any Other.

                                    Page 12
<PAGE>
 
         ARTICLE XIV - SERVICES, UTILITIES, MAINTENANCE AND FACILITIES

         16.1 Operating Services. USWC, at its sole cost and expense, shall
maintain for the Physical Collocation Site customary Premises services,
utilities (excluding telephone facilities), including janitor and, where
applicable, elevator services, 24 hours a day, 365 days a year. The
Interconnector shall be permitted to have a single-line business telephone
service for the Premises subject to applicable USWC tariffs.

         16.2 Utilities. USWC will provide negative DC and AC power, back-up
power, heat, air conditioning and other environmental support necessary for the
Interconnector's equipment, in the same manner that it provides such support
items for its own equipment within that Premises.

         16.3 Maintenance. USWC shall maintain the exterior of the Premises and
grounds, and all entrances, stairways, passageways, and exits used by the
Interconnector to access the Premises.

         16.4 Legal Requirements. USWC agrees to make, at its expense, all
changes and additions to the Premises required by laws, ordinances, orders or
regulations of any municipality, county, state or other public authority
including the furnishing of required sanitary facilities and fire protection
facilities.

         ARTICLE XV - DISPUTE RESOLUTION

         For disputes arising out of this Agreement, the parties agree that they
will follow the procedures as set forth in Section XXXIV of the Interconnection
Agreement executed between the parties.

         ARTICLE XVI - SUCCESSORS BOUND

         Without limiting Article XI hereof, the conditions and agreements
contained herein shall bind and inure to the benefit of USWC, the Interconnector
and their respective successors and, except as otherwise provided herein,
assigns.

         ARTICLE XVII - CONFLICT OF INTEREST

         The Interconnector represents that no employee or agent of USWC has
been or will be employed, retained, paid a fee, or otherwise has received or
will receive any personal compensation or consideration from the Interconnector,
or any of the Interconnector's employees or agents in connection with the
arranging or negotiation of this Agreement or associated documents. USWC
represents that no employee or agent of the Interconnector has been or will be
employed, retained, paid a fee, or otherwise has received or will receive any
personal compensation or consideration from USWC, or any of USWC's employees or
agents in connection with the arranging or negotiation of this Agreement or
associated documents.

                                    Page 13
<PAGE>
 
         ARTICLE XVIII - NON-EXCLUSIVE REMEDIES

         No remedy herein conferred upon is intended to be exclusive of any
other remedy in equity, provided by law, or otherwise, but each shall be in
addition to every other such remedy.

         ARTICLE XIX - NOTICES

        Except as may be specifically permitted in this Agreement, any notice,
demand, or payment required or desired to be given by on party to the other
shall be in writing and shall be valid and sufficient if dispatched by
registered or certified mail, return receipt requested, postage prepaid, in the
United States mail, or via professional overnight courier, or by facsimile
transmission; provided, however, that notices sent by such registered or
certified mail shall be effective on the third business day after mailing and
those sent by facsimile transmission shall only be effective on the date
transmitted if such notice is also sent by such registered or certified mail no
later than the next business day after transmission, all addressed as follows:

                    USWC
                    Director Interconnection Services
                    1801 California, Room 2340
                    Denver, CO 80202

                    Focal Communications Corporation of Washington
                    Director, Regulatory Affairs (fax 312-895-8403)
                    200 N. LaSalle Street, Suite 800
                    Chicago, Illinois 60601

Either party hereto may change its address by written notice given to the other
party hereto in the manner set forth above.

         ARTICLE XX - COMPLIANCE WITH LAWS

         The Interconnector and all persons acting through or on behalf of the
Interconnector shall comply with the provisions of the Fair Labor Standards Act,
the Occupational Safety and Health Act, and all other applicable federal, state,
county, and local laws, ordinances, regulations and codes (including
identification and procurement of required permits, certificates, approvals and
inspections) in its performance hereunder.

         ARTICLE XXI - INSURANCE

         Interconnector agrees to maintain, at Interconnector's expense during
the entire time that Interconnector and its equipment occupies Premises: (i)
General Liability Insurance in an amount not less than one million dollars
($1,000,000.00) per occurrence for bodily injury or property damage, (ii)
Employer's Liability in an amount not less than five hundred thousand dollars
($500,000.00) per occurrence, (iii) Worker's Compensation in an amount not less
than that prescribed by statutory limits, and (iv) Umbrella/Excess Liability
coverage in an amount of five million dollars ($5,000,000.00) excess of coverage
specified above.

                                    Page 14
<PAGE>
 
         Each policy shall be underwritten by an insurance company having a BEST
insurance rating of B+VII or better, and which is authorized to do business in
the jurisdiction in which the Premises is located.

         Interconnector shall furnish USWC with certificates of insurance which
evidence the minimum levels of insurance set forth herein and which name USWC as
an additional insured. The Interconnector shall arrange for USWC to receive at
least thirty (30) days advance written notice from the Interconnector's
insurance companies of cancellation and shall notify USWC in writing to achieve
its approval should the Interconnector later elect to self-insure.

         ARTICLE XXII - US WEST'S RIGHT OF ACCESS

         USWC, its agents, employees, and other USWC-authorized persons shall
have the right to enter the Premises at any reasonable time to examine its
conditions, make repairs required to be made by USWC hereunder, and for any
other purpose determined to be necessary by USWC in complying with the terms of
this Agreement and providing telecommunications services at the Physical
Collocation Site. USWC may access the Premises at any time for purposes of
averting any threat of harm imposed by the Interconnector or its equipment or
facilities upon the operation of USWC equipment, facilities and/or personnel
located outside of the Premises. If routine inspections are required, they shall
be conducted at a mutually agreeable time. USWC agrees to minimize and to limit
any and all instances in which access by its employees, agents or other persons
whom it authorizes takes place and agrees not to allow any party which is
suspected of any previous instance of wrongdoing of any kind or who has been
subject to any form of discipline by USWC at any time in the past to enter
Premises. USWC will, in all instances, provide to Interconnector written
notification of its access to Premises any time that such access occurs without
advance notice to the Interconnector and such written notification shall contain
a brief explanation of the reason for such access as well as the name(s) and
title(s) of such persons and USWC shall provide to Interconnector such written
notice within twenty-four (24) hours of the time when such access took place.

         ARTICLE XXIII- OTHER COLLOCATION AGREEMENTS

The parties agree that the provisions of Section 252(i) of the Act shall apply,
including state and federal interpretive regulations in effect from time to
time.

         ARTICLE XXIV - MISCELLANEOUS

         27.1 Exhibits. The following Exhibits are attached hereto and made part
         hereof:

         Exhibit A, The Schedule of All Interstate and Intrastate Monthly
         Recurring Charges
         Exhibit B The Schedule of All Interstate and Intrastate Nonrecurring
         Charges
         Exhibit C, Working Drawings and Specifications Entitled
         Exhibit D, Point of Interconnection

         27.2 Variations. In the event of variation or discrepancy between any
duplicate originals hereof, including exhibits, the original Agreement shall
control.

                                    Page 15
<PAGE>
 
         27.3 Governing Law. This Agreement shall be governed by the laws of the
State in which the Premises are located, without regard to the choice of law
principles thereof.

         27.4 Joint and Several. If Interconnector constitutes more than one
person, partnership, corporation, or other legal entities, the obligation of all
such entities under this Agreement is joint and several.

         27.5 Future Negotiations. USWC may refuse requests for additional space
at the Physical Collocation Site or in any other USWC site if the Interconnector
is in material breach of this Agreement. In such event, the Interconnector
hereby releases and shall hold USWC harmless

         27.6 Severability. With the exception of the requirements, obligations,
and rights set forth in Article II hereof, if any of the provisions hereof are
otherwise deemed invalid, such invalidity shall not invalidate the entire
Agreement, but rather the entire Agreement shall be construed as if not
containing the particular invalid provision(s), and the rights and obligations
of USWC and the Interconnector shall be construed accordingly.

         27.7 Paragraph Headings and Article Numbers. The headings of the
articles paragraphs herein are inserted for convenience only and are not
intended to affect the meaning or interpretation of this agreement.

         27.8 Entire Agreement. Recognizing that this Agreement is component of
a Interconnection Agreement, this Agreement with the attached schedules and
exhibits, and referenced documentation and materials attached hereto set forth
the entire understanding of the parties with respect to physical collocation and
supersedes all prior agreements, arrangements and understandings relating to
this subject matter and may not be changed except in writing by the parties. No
representation, promise, inducement or statement of intention has been made by
either party which is not embodied herein, and there are no other oral or
written understandings or agreements between the parties relating to the subject
matter hereof except as may be referenced herein.

         27.9 No Third Party Beneficiaries. Nothing in this Agreement is
intended, nor shall be deemed, to confer any rights or remedies upon any person
or legal entity not a party hereto.

         27.10 Binding Effect. (a) This Agreement is binding upon the parties
hereto, their respective executors, administrators, heirs, assigns and
successors in interest; (b) all obligations by either party which expressly or
by their nature survive the expiration or termination of this Agreement shall
continue in full force and effect subsequent to and notwithstanding its
expiration or termination and until they are satisfied in full or by their
nature.

         27.11 Force Maieure. Neither party shall be liable for any delay or
failure in performance of any part of this Agreement from any cause beyond its
control and without its fault or negligence including, without limitation, acts
of nature, acts of civil or military authority, government regulations,
embargoes, epidemics, terrorist acts, riots, insurrections, fires, explosions,
earthquakes, nuclear accidents, floods, work stoppages, equipment failure, cable
cuts, power blackouts, volcanic action, other major environmental disturbances,
unusually

                                    Page 16
<PAGE>
 
severe weather conditions, inability to secure products or services of other
persons or transportation facilities or acts or omissions of transportation
carriers (collectively, a "Force Majeure Condition"). If any Force Majeure
Condition occurs, the party delayed or unable to perform shall give prompt
notice to the other party and shall take all reasonable steps to correct the
force Majeure Condition. During the pendancy of such Condition, the duties of
the parties under this agreement affected by the Force Majeure Condition shall
be abated and shall resume without liability thereafter.

         IN WITNESS WHEREOF, the duly authorized representatives of the parties
have executed and delivered this Agreement as of the day and year first above
written.

US WEST COMMUNICATIONS:

By:  __________________________________

Title:  _______________________________

Date:  ________________________________

INTERCONNECTOR:

By:____________________________________

Title:_________________________________

Date: _________________________________



                                    Page 17
<PAGE>
 
                                   Exhibit A

    The Schedule of All Interstate and Intrastate Monthly Recurring Charges

                         To be provided by the Parties



                                    Page 18
<PAGE>
 
                                   Exhibit B

        The Schedule of All Interstate and Intrastate Nonrecurring Charges

                         To be Provided by the Parties



                                    Page 19
<PAGE>
 
                                   Exhibit C

                  Working Drawings and Specifications Entitled

                         To be provided by the Parties




                                    Page 20
<PAGE>
 
                                   Exhibit D

                            Point of Interconnection

                         To be Provided by the Parties


                                    Page 21

<PAGE>
 
                                                                    EXHIBIT 10.5

                                                              EXECUTION ORIGINAL



       INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                       TELECOMMUNICATIONS ACT OF 1996

                         Dated as of January 29, 1997/1/
                                                      -

                                by and between

                    AMERITECH INFORMATION INDUSTRY SERVICES,
                    a division of Ameritech Services, Inc.
               on behalf of and as agent for Ameritech Michigan

                                      and

                 FOCAL COMMUNICATIONS CORPORATION OF MICHIGAN



____________________________

/1/     See Footnote 21 on Signature Page.
 -
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE> 
<CAPTION> 
                                                                 Page
                                                                 ----
<S>                                                              <C> 
ARTICLE I
     DEFINITIONS AND CONSTRUCTION...........................        2
     1.1   Structure........................................        2
     1.2   Defined Terms....................................        2
     1.3   Interpretation...................................        2
     1.4   Joint Work Product...............................        2
     1.5   Regional Matters.................................        3

ARTICLE II
     GENERAL SERVICE RELATED PROVISIONS.....................        3
     2.1   Interconnection Activation Date..................        3
     2.2   Bona Fide Request................................        4
     2.3   Technical References.............................        4
     2.4   Use of Services..................................        4

ARTICLE III
     INTERCONNECTION PURSUANT TO SECTION 251(c)(2)..........        4
     3.1   Scope............................................        4
     3.2   Interconnection Points and Methods...............        5
     A3.2  Focal Alternative Methods of Interconnection.....        5
     B3.2  Ameritech Alternative Methods of Interconnection.        6
     C3.2  SS7 Interconnection..............................       10
     3.3   Fiber-Meet.......................................       11
     3.4   Interconnection in Additional LATAs..............       13
     3.5   Additional Interconnection in Existing LATAs.....       13
     3.6   Nondiscriminatory Interconnection................       13
     3.7   Network Management...............................       14
     3.8   Standards of Performance.........................       14
     3.9   9-1-1 Service....................................       15

ARTICLE IV
     TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE
     SERVICE TRAFFIC PURSUANT TO SECTION 251(c)(2)..........       18
     4.1   Scope of Traffic.................................       18
     4.2   Limitations......................................       18
     4.3   Trunk Group Architecture and Traffic Routing.....       19
     4.4   Signaling........................................       19
     4.5   Grades of Service................................       20
     4.6   Measurement and Billing..........................       20
     4.7   Reciprocal Compensation Arrangements -- Section 
               251(b)(5)....................................       21
</TABLE> 

                                      -i-
<PAGE>
 
<TABLE> 
<CAPTION> 
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                                                                 ----
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ARTICLE V
     TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC 
     PURSUANT TO 251(c)(2)..................................       22
     5.1   Scope of Traffic.................................       22
     5.2   Trunk Group Architecture and Traffic Routing.....       22

ARTICLE VI
     MEET-POINT BILLING ARRANGEMENTS........................       22
     6.1   Meet-Point Billing Services......................       22
     6.2   Data Format and Data Transfer....................       23
     6.3   Errors or Loss of Access Usage Data..............       24
     6.4   Payment..........................................       24
     6.5   Additional Limitations of Liability Applicable 
               to Meet-Point Billing Arrangements...........       24

ARTICLE VII
     TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC....       25
     7.1   Information Services Traffic.....................       25
     7.2   BLV/BLVI Traffic.................................       26
     7.3   Transit Service..................................       26

ARTICLE VIII
     INSTALLATION, MAINTENANCE, TESTING AND REPAIR..........       28
     8.1   Plan.............................................       28
     8.2   Operation and Maintenance........................       28
     8.3   Installation, Maintenance, Testing, and Repair...       29
     8.4   Additional Terms.................................       29

ARTICLE IX
     UNBUNDLED ACCESS -- SECTION 251(c)(3)..................       29
     9.1   Access to Network Elements.......................       29
     9.2   Network Elements.................................       30
     9.3   Combination of Network Elements..................       30
     9.4   Nondiscriminatory Access to and Provision of
               Network Elements.............................       32
     9.5   Provisioning of Network Elements.................       32
     9.6   Availability of Additional or Different Quality
               Network Elements.............................       33
     9.7   Pricing of Unbundled Network Elements............       33
</TABLE> 

                                     -ii-
<PAGE>
 
<TABLE> 
<CAPTION> 
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                                                                 ---- 
<S>                                                              <C> 
     9.8   Billing..........................................       34
     9.9   Maintenance of Unbundled Network Elements........       34
     9.10  Standards of Performance.........................       34

ARTICLE X
     RESALE AT WHOLESALE RATES -- SECTION 251(c)(4).........       36
     10.1  Telecommunications Services Available for Resale
               at Wholesale Rates...........................       36
     10.2  Other Services...................................       37
     10.3  Limitations on Availability of Resale Services...       37
     10.4  Additional Charges for Resale Services...........       38
     10.5  Restrictions on Resale Services..................       38
     10.6  New Resale Services; Changes in Provision of
               Resale Services..............................       39
     10.7  Operations Support Systems Functions.............       39
     10.8  Nondiscriminatory Provision of Resale Services...       39
     10.9  Standards of Performance.........................       39
     10,10 Branding.........................................       41
     10.11 Primary Local Exchange and Interexchange Carrier
               Selections...................................       42
     10.12 Functionality Required To Support Resale Service.       44
     10.13 Service Functions................................       44
     10.14 Responsibilities of Focal........................       47
     10.15 Responsibilities of Ameritech ...................       47
     10.16 Exchange of Billing Information..................       48
     10.17 Use of Service...................................       49

ARTICLE XI
     NOTICE OF CHANGES -- SECTION 251(c)(5).................       50

ARTICLE XII
     COLLOCATION -- SECTION 251(c)(6).......................       50
     12.1  Physical Collocation.............................       50
     12.2  Virtual Collocation in Physical Collocation 
               Space........................................       50
     12.3  Virtual Collocation in Virtual Collocation Space.       50
     12.4  Nondiscriminatory Collocation....................       51
     12.5  Eligible Equipment...............................       51
     12.6  Transmission Facility Options....................       51
     12.7  Interconnection with other Collocated Carriers...       51
     12.8  Interconnection Points and Cables................       52
     12.9  Allocation of Collocation Space..................       52
     12.10 Security Arrangements............................       53
</TABLE> 

                                     -iii-
<PAGE>
 
<TABLE> 
<CAPTION> 
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                                                                 ----
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     12.11 Subcontractor and Vendor Approval................       53
     12.12 Delivery of Collocated Space.....................       53
     12.13 Pricing .........................................       57
     12.14 Billing..........................................       57
     12.15 Common Requirements..............................       57
     12.16 Additional Requirements..........................       57
     12.17 Protection of Service and Property...............       57
     12.18 Standards of Performance.........................       58

ARTICLE XIII
     NUMBER PORTABILITY -- SECTION 251(b)(2)................       58
     13.1  Provision of Local Number Portability............       58
     13.2  Interim Number Portability ("INP")...............       58
     13.3  Remote Call Forwarding ("RCF")...................       58
     13.4  Direct Inward Dialing............................       59
     13.5  NXX Migration....................................       60
     13.6  Other Interim Number Portability Provisions......       60
     13.7  Compensation on Traffic to INP'ed Numbers........       61
     13.8  Pricing For Interim Number Portability...........       62
     13.9  Permanent Number Portability.....................       62
     13.10 Other INP Methods................................       62

ARTICLE XIV
     DIALING PARITY-- SECTIONS 251(b)(3) and 271(e)(2)(B)...       62

ARTICLE XV
     DIRECTORY LISTINGS -- SECTION 251(b)(3)................       62
     15.1  Directory Listings...............................       62
     15.2  Listing and Listing Updates......................       63

ARTICLE XVI
     ACCESS TO POLES, DUCTS, CONDUITS AND RIGHTS-OF-WAY
           -- SECTIONS......................................       64
     16.1  Structure Availability...........................       64
     16.2  Franchises, Permits and Consents.................       65
     16.3  Access and Modifications.........................       65
     16.4  Installation and Maintenance Responsibility......       66
     16.5  Installation and Maintenance Standards...........       67
     16.6  Implementation Team..............................       67
     16.7  Access Requests..................................       67
</TABLE>                                                          

                                     -iv-
<PAGE>
 
<TABLE> 
<CAPTION> 
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                                                                 ----
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     16.8  Unused Space.....................................       67
     16.9  Maintenance Ducts................................       67
     16.10 Applicability....................................       67
     16.11 Other Arrangements...............................       68
     16.12 Cost of Certain Modifications....................       68
     16.13 Maps and Records.................................       68
     16.14 Focal Access.....................................       68
     16.15 Occupancy Permit.................................       68
     16.16 Inspections......................................       69
     16.17 Damage to Attachments............................       69
     16.18 Charges..........................................       69
     16.19 Nondiscrimination................................       69
     16.20 Interconnection..................................       69
     16.21 Cost Imputation..................................       69
     16.22 Structure Leasing Coordinator....................       70
     16.23 State Regulation.................................       70
     16.24 Abandonments, Sales or Dispositions..............       70
     16.25 Standards of Performance.........................       70

ARTICLE XVII
     REFERRAL ANNOUNCEMENT..................................       70

ARTICLE XVIII
     IMPLEMENTATION TEAM AND IMPLEMENTATION PLAN............       71
     18.1  Implementation Team..............................       71
     18.2  Implementation Plan..............................       71
     18.3  Action of Implementation Team....................       73
     18.4  Further Coordination and Performance.............       73
     18.5  Operational Review...............................       73
     18.6  Additional Duties of Implementation Team.........       74

ARTICLE XIX
     GENERAL RESPONSIBILITIES OF THE PARTIES................       74
     19.1  Compliance with Implementation Schedule..........       75
     19.2  Compliance with Applicable Law...................       75
     19.3  Necessary Approvals..............................       75
     19.4  Environmental Hazards............................       75
     19.5  Forecasting Requirements.........................       75
     19.6  Certain Network Facilities.......................       76
</TABLE> 

                                      -v-
<PAGE>
 
<TABLE> 
<CAPTION> 
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                                                                 ----
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     19.7  Traffic Management and Network Harm..............       76
     19.8  Insurance........................................       77
     19.9  Labor Relations..................................       77
     19.10 Good Faith Performance...........................       77
     19.11 Responsibility to Customers......................       77
     19.12 Unnecessary Facilities...........................       77
     19.13 Cooperation......................................       77
     19.14 NXX Code Administration..........................       77
     19.15 LERG Listings....................................       77
     19.16 LERG Use.........................................       78
     19.17 Switch Programming...............................       78
     19.18 Transport Facilities.............................       78

ARTICLE XX
     PROPRIETARY INFORMATION................................       78
     20.1  Definition of Proprietary Information............       78
     20.2  Disclosure and Use...............................       79
     20.3  Government Disclosure............................       81
     20.4  Ownership........................................       81

ARTICLE XXI
     TERM AND TERMINATION...................................       82
     21.1  Term.............................................       82
     21.2  Renegotiation of Certain Terms...................       82
     21.3  Default..........................................       83
     21.4  Transitional Support.............................       83
     21.5  Payment Upon Expiration or Termination...........       83

ARTICLE XXII
     DISCLAIMER OF REPRESENTATIONS AND WARRANTIES...........       83

ARTICLE XXIII
     CANCELLATION CHARGES...................................       84

ARTICLE XXIV
     SEVERABILITY...........................................       84
     24.1  Severability.....................................       84
     24.2  Non-Contravention of Laws........................       84
</TABLE> 

                                     -vi-
<PAGE>
 
<TABLE> 
<CAPTION> 

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ARTICLE XXV                                             
     INDEMNIFICATION........................................       84
     25.1  General Indemnity Rights.........................       84
     25.2  Indemnification Procedures.......................       85

ARTICLE XXVI
     LIMITATION OF LIABILITY................................       86
     26.1  Limited Responsibility...........................       86
     26.2  Apportionment of Fault...........................       86
     26.3  Limitation of Damages............................       86
     26.4  Limitations in Tariffs...........................       87
     26.5  Consequential Damages............................       87
     26.6  Remedies.........................................       87

ARTICLE XXVII
     BILLING................................................       88
     27.1  Billing..........................................       88
     27.2  Recording........................................       88
     27.3  Payment Of Charges...............................       88
     27.4  Late Payment Charges.............................       88
     27.5  Adjustments......................................       89
     27.6  Interest on Unpaid Amounts.......................       89

ARTICLE XXVIII
     AUDIT RIGHTS, DISPUTED AMOUNTS AND DISPUTE RESOLUTION..       89
     28.1  Audit Rights.....................................       89
     28.2  Disputed Amounts.................................       91
     28.3  Dispute Escalation and Resolution................       92
     28.4  Equitable Relief.................................       92

ARTICLE XXIX
     REGULATORY APPROVAL....................................       93
     29.1  Commission.......................................       93
     29.2  Tariffs..........................................       93
     29.3  Amendment or Other Changes to the Act,
                Reservation of Rights.......................       94
     29.4  Regulatory Changes...............................       94
     29.5  Proxy Rates......................................       94
</TABLE> 

                                     -vii-
<PAGE>
 
<TABLE> 
<CAPTION> 
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ARTICLE XXX
       MISCELLANEOUS........................................       94
       30.1  Authorization..................................       94
       30.2  Designation of Affiliate.......................       95
       30.3  Subcontracting.................................       95
       30.4  Independent Contractor.........................       95
       30.5  Force Majeure..................................       95
       30.6  Governing Law..................................       96
       30.7  Taxes..........................................       96
       30.8  Non-Assignment.................................       97
       30.9  Non-Waiver.....................................       97
       30.10 Notices........................................       97
       30.11 Publicity and Use of Trademarks or Service 
                Marks.......................................       98
       30.12 Nonexclusive Dealings..........................       98
       30.13 No Third Party Beneficiaries, Disclaimer of 
                Agency......................................       99
       30.14 No License.....................................       99
       30.15 Survival.......................................       99
       30.16 Scope of Agreement.............................       99
       30.17 Counterparts...................................       99
       30.18 Entire Agreement...............................       99

ARTICLE XXXI
       AMERITECH COLLOCATION................................      100
       31.1  Physical Collocation...........................      100
       31.2  Eligible Equipment.............................      100
       31.3  Transmission Facility Options..................      100
       31.4  Interconnection Points and Cables..............      100
       31.5  Allocation of Collocation Space................      101
       31.6  Subcontractor and Vendor Approval..............      101
       31.7  Delivery of Collocated Space...................      101
       31.8  Pricing........................................      102
       31.9  Billing........................................      102
       31.10 Additional Requirements........................      102
       31.11 Protection of Service and Property.............      103
       31.12 Standards of Performance.......................      104
</TABLE>

                                    -viii-
<PAGE>
 
             INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252
                     OF THE TELECOMMUNICATIONS ACT OF 1996

      This Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996 ("AGREEMENT"), is effective as of the 29th day of
January, 1997/2/ (the "EFFECTIVE DATE"), by and between Ameritech Information
              -
Industry Services, a division of Ameritech Services, Inc., a Delaware
corporation with offices at 350 North Orleans, Third Floor, Chicago, Illinois
60654, on behalf of and as agent for Ameritech Michigan (Ameritech Michigan
referred to herein as "AMERITECH") and Focal Communications Corporation of
Michigan, a Delaware corporation, with offices at 200 N. LaSalle Street, Suite
800, Chicago, Illinois 60601 ("FOCAL").

                                   RECITALS

      A.  Ameritech is an Incumbent Local Exchange Carrier as defined by the
Act, authorized to provide certain Telecommunications Services within Michigan.

      B.  Ameritech is engaged in the business of providing, among other things,
local Telephone Exchange Service within Michigan.

      C.  Focal has been granted authority to provide certain local Telephone
Exchange Services within Michigan and is a Local Exchange Carrier as defined by
the Act.

      D.  The Parties desire to Interconnect their telecommunications networks
and facilities to comply with the Act, and exchange traffic so that their
respective residential and business Customers may communicate with each other
over, between and through such networks and facilities.

      E.  The Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will Interconnect their networks and facilities and provide to each
other Telecommunications Services as required by the Act as set forth herein.

      NOW, THEREFORE, in consideration of the mutual premises and the covenants
contained herein and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Focal and Ameritech hereby agree
as follows.


___________________

/2/   See Footnote 21 on Signature Page.
 -
<PAGE>
 
                                   ARTICLE I
                         DEFINITIONS AND CONSTRUCTION
                                        
      1.1  STRUCTURE.

This Agreement includes certain Exhibits and Schedules which immediately follow
this Agreement, all of which are hereby incorporated in this Agreement by this
reference and constitute a part of this Agreement.

      1.2  DEFINED TERMS. Capitalized terms used in this Agreement shall have
the respective meanings specified in SCHEDULE 1.2 or as defined elsewhere in
                                     ------------
this Agreement.

      1.3  INTERPRETATION.

           (a)  The definitions in SCHEDULE 1.2 shall apply equally to both the
                                   ------------
                singular and plural forms of the terms defined. Whenever the
                context may require, any pronoun shall include the
                corresponding masculine, feminine and neuter forms. The words
                "INCLUDE," "INCLUDES" AND "INCLUDING" shall be deemed to be
                followed by the phrase "WITHOUT LIMITATION". The words "SHALL"
                and "WILL" are used interchangeably throughout this Agreement
                and the use of either connotes a mandatory requirement. The use
                of one or the other shall not mean a different degree or right
                or obligation for either Party.

           (b)  References herein to Articles, Sections, Exhibits and Schedules
                shall be deemed to be references to Articles and Sections of, 
                and Exhibits and Schedules to, this Agreement unless the context
                shall otherwise require.

           (c)  The headings of the Articles, Sections, Exhibits and Schedules
                are inserted for convenience of reference only and are not
                intended to be a part of or to affect the meaning or
                interpretation of this Agreement.

           (d)  Unless the context shall otherwise require, any reference to any
                agreement, other instrument (including Ameritech, Focal or
                other third party offerings, guides or practices), statute,
                regulation, rule or tariff is to such agreement, instrument,
                statute, regulation, rule or tariff as amended and supplemented
                from time to time (and, in the case of a statute, regulation,
                rule or tariff, to any successor provision).

           (e)  In the event of a conflict between the provisions of this
                Agreement and the Act, the provisions of the Act shall govern.

      1.4  JOINT WORK PRODUCT. This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and
shall be fairly interpreted in

                                       2
<PAGE>
 
accordance with its terms and, in the event of any ambiguities, no inferences
shall be drawn against either Party.

      1.5  REGIONAL MATTERS.

           (a)  Focal has a regional administrative structure in which its
                central region ("REGION") comprises the states of Illinois,
                Ohio, Indiana, Michigan and Wisconsin, states in which Ameritech
                Michigan and its Affiliates conduct business operations and in
                which Ameritech Michigan and certain of its Affiliates are
                Incumbent Local Exchange Carriers. Ameritech Michigan and Focal
                currently perform, or cause their Affiliates to perform,
                administrative and specialized business operations on a
                centralized basis in the Region.

           (b)  The Parties shall cooperate in the administration and
                performance of this Agreement and any other agreements between
                the Parties and their Affiliates approved under Section 252 of
                the Act relating to the Parties' provision of
                Telecommunications Services in the Region (the "REGIONAL
                INTERCONNECTION AGREEMENTS") so that the following are
                accomplished: 

                (1)  Whenever this Agreement requires a procedure for deployment
                     of the relevant facilities, services and functions,
                     including formation of an Implementation Team and the
                     development of an Implementation Plan, the Parties shall,
                     to the maximum extent practicable in light of local state
                     differences, use a single Implementation Team to develop a
                     single Implementation Plan which will satisfy the
                     requirements of all Regional Interconnection Agreements.
                     Except as necessary to accommodate individual state
                     differences or requirements, meetings of the Implementation
                     Team shall be held in Chicago, Illinois; and

                (2)  The Parties agree that they will use their best efforts to
                     maintain single points of contact and operational
                     interfaces for all Regional Interconnection Agreements.


                                  ARTICLE II
                      GENERAL SERVICE RELATED PROVISIONS

      2.1  INTERCONNECTION ACTIVATION DATE

      Subject to the terms and conditions of this Agreement, Interconnection of
the Parties' facilities and equipment pursuant to ARTICLES III and IV for the
                                                  ------------     --
transmission and routing of Telephone Exchange Service traffic and Exchange
Access traffic, and Interconnection of the Parties' facilities and equipment to
provide Focal access to Ameritech's unbundled Network Elements pursuant to
ARTICLE IX, shall be established on or before the corresponding "INTERCONNECTION
- ----------

                                       3
<PAGE>
 
ACTIVATION DATE" shown for each LATA and Wire Center set forth on SCHEDULE 2.1.
                                                                  ------------
The Parties shall refine estimated Interconnection Activation Dates and identify
additional Interconnection Activation Dates using the principles set forth in
SECTION 3.4.4. SCHEDULE 2.1 may be revised and supplemented from time to time
- -------------  ------------                                                 
upon the mutual agreement of the Parties to reflect the Interconnection of
additional LATAs and Wire Centers by attaching one or more supplementary
schedules to such Schedule.

      2.2  BONA FIDE REQUEST.

      Any request by Focal for certain services, including features,
capabilities, functionality, Network Elements or Combinations that are not
otherwise provided by the terms of this Agreement at the time of such request
shall be made pursuant to the Bona Fide Request process set forth on SCHEDULE
                                                                     --------
2.2.
- ---

      2.3  TECHNICAL REFERENCES.

      Technical References that describe the practices, procedures and
specifications for certain services (and the applicable interfaces relating
thereto) are listed on SCHEDULE 2.3 (THE "TECHNICAL REFERENCE SCHEDULE") to
                       ------------                                       
assist the Parties in meeting their respective responsibilities hereunder.

      2.4  USE OF SERVICES.

      Subject to the requirements of this Agreement, the Act, the Commission and
the FCC, Focal may, subject to the payment to Ameritech of all applicable
charges, add to, delete from or change a purchased Resale Service or Network
Element in the provision of service to its Customer.

                                  ARTICLE III
                 INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

      3.1  SCOPE.

      ARTICLE III describes the physical architecture for Interconnection of the
      -----------                                                              
Parties' facilities and equipment for the transmission and routing of Telephone
Exchange Service traffic and Exchange Access traffic between the respective
business and residential Customers of the Parties pursuant to Section 251(c)(2) 
of the Act. Interconnection may not be used solely for the purpose of
originating a Party's own interexchange traffic. ARTICLES IV and V prescribe
                                                  -----------     -          
the specific logical trunk groups (and traffic routing parameters) which will be
configured over the physical Interconnections described in this ARTICLE III
                                                                -----------
related to the transmission and routing of Telephone Exchange Service traffic
and Exchange Access traffic, respectively. Other trunk groups, as described in
this Agreement, may be configured using this architecture.

                                       4
<PAGE>
 
      3.2  INTERCONNECTION POINTS AND METHODS.

           3.2.1  In each LATA identified on SCHEDULE 2.1, Focal and Ameritech
                                             ------------                 
shall Interconnect their networks at the correspondingly identified Ameritech
and Focal Wire Centers on SCHEDULE 2.1 for the transmission and routing within
                          ------------
that LATA of Telephone Exchange Service traffic and Exchange Access traffic
pursuant to Section 251(c)(2) of the Act.

           3.2.2  Interconnection in each LATA shall be accomplished at any
technically feasible point within the Parties' networks through either (i)
Collocation in Ameritech's Wire Centers as provided in ARTICLE XII or (ii) any
                                                       -----------           
other Interconnection method to which the Parties may agree in advance of the
applicable Interconnection Activation Date for a given LATA and which is
consistent with the Act, including a Fiber-Meet as provided in SECTION 3.3.
                                                               -----------
Notwithstanding the foregoing, as provided in Section 251(c)(2) of the Act,
Focal, at its option, may request Interconnection of its facilities and
equipment to Ameritech's network at any technically feasible point in
Ameritech's network, including a mid-span meet arrangement at any transmission
rate for a Telecommunications Service that Ameritech offers to itself, its
subsidiaries, its Affiliates or other persons.

           3.2.3  If Focal elects Collocation as an Interconnection method or
elects a network architecture that requires Ameritech to Interconnect with
Focal's facilities via Collocation, Focal agrees to provide to Ameritech
Collocation for purposes of that Interconnection on a nondiscriminatory basis
and on rates, terms and conditions to be negotiated by the Parties under a
separate agreement that are no less favorable than Focal provides to other
similarly situated Telecommunications Carriers.


     A3.2  FOCAL ALTERNATIVE METHODS OF INTERCONNECTION. As an alternative to
           --------------------------------------------                    
Collocation in Ameritech's Wire Center or Fiber Meet as currently provided for
in this Agreement, Focal may interconnect with Ameritech for purposes of
delivering Local Traffic and IntraLATA Toll Traffic originating in Focal's
network for termination on Ameritech's network by using the alternative method
of Interconnection as described below.

           A3.2.1 Under this method of Interconnection, Focal will transport
           Local Traffic and IntraLATA Toll Traffic to Ameritech's Tandem or End
           Offices by using trunks (i.e., DS1's) on existing DS3 access
           facilities between Focal's Central Office Switches and the Ameritech
           Wire Center. Such facilities may be provided by Ameritech, Focal,
           other vendors used by Focal or Ameritech, or a combination thereof.

           A3.2.2 If additional capacity is needed for Interconnection under
           this method, Focal will provision such facilities (i) from Ameritech
           under its access tariff; (ii) from Focal's own facility inventory; or
           (iii) from an alternative access vendor.

                                       5
<PAGE>
 
           A3.2.3  Focal agrees that until such time as may be agreed to by the
           Parties, or ordered by any court, regulatory authority or other
           tribunal of any dispute, Focal will not use the Dedicated Transport
           Network Element (without access via Collocation) for purposes of
           Interconnection pursuant to the method described in this SECTION
                                                                    -------
           A.3.2.
           -----

           A3.2.4 Focal must interconnect with Ameritech at a DS1 Bandwidth.
           Ameritech may allow Interconnection at other bandwidths where
           technically feasible and mutually agreeable at termination charges to
           be agreed upon by the Parties.

     B3.2  AMERITECH ALTERNATIVE METHODS OF INTERCONNECTION.  Ameritech will 
           ------------------------------------------------
Interconnect with Focal for purposes of delivering Local Traffic and IntraLATA 
Toll Traffic originating in Ameritech's network for termination on Focal's 
network by using one of the following methods or such other methods as may be 
agreed upon by the Parties.

           a)      Collocation in the LEC Access Equipment Room in Focal's Wire 
           Centers as described in SECTION B3.2.1 below:
                                   --------------

           b)      Leasing of DS1 facilities from Focal as described in SECTION 
                                                                        ------- 
           B3.2.2 below; or
           ------

           c)      Leasing facilities from third parties collocated in Focal's 
           space.
                
           B3.2.1  Collocation in Focal Wire Center. Under this method of
                   -------------------------------- 
           Interconnection, Ameritech may transport Local Traffic and IntraLATA
           Toll Traffic to the designated Point of Interconnection ("POI") in
           Focal's Wire Centers by using its self-provided facilities which are
           terminated in Ameritech's equipment located in the LEC Access
           Equipment Room/3/ in Focal's Wire Center used to provide total
                          - 
           services access/4/ for Focal or in Focal provided equipment (when
                           - 
           both Focal and Ameritech are located in the same building).

                   B3.2.1.1  Collocation for purposes of this method of
                   Interconnection will be furnished by Focal under the same
                   terms and conditions that it is provided today to Ameritech
                   for total service access terminal equipment. However, since
                   these terms and conditions may vary from Focal Wire Center to
                   Focal Wire Center, Focal agrees that the terms and conditions
                   described in ARTICLE XXXI will apply. Focal agrees to provide
                                ------------
                   such Collocation on a non-


______________________

/3/    The LEC Access Equipment Room is the space Focal furnishes to Ameritech
       pursuant to Section 2.3.3 of Ameritech Tariff F.C.C. No.2.

/4/    Total service access are access services purchased by Focal from 
 -
       Ameritech to provide switched or dedicated access to Focal Customers.

                                       6
<PAGE>
 
                   discriminatory basis in accordance with the requirements of
                   Section 3.2.3 of the Agreement and Section 202(a) of the Act.

                   B3.2.1.2  In order to accommodate this method of
                   Interconnection, Ameritech may utilize existing equipment
                   installed for the purposes of providing total service access
                   for Focal's use or place additional equipment in the space.

                   B3.2.1.3  Ameritech will interconnect with Focal at each
                   Focal Wire Center in the LATA from each Ameritech Wire Center
                   at which Focal elects to interconnect with Ameritech.
                   Therefore, for each Wire Center combination specified in
                   SCHEDULE 2.1, traffic will terminate between the Parties'
                   ------------
                   respective networks. In those LATA's where Focal does not
                   have a Central Office Switch, Focal will designate a facility
                   Point of Presence (POP) in the LATA where Ameritech will
                   interconnect with Focal. Any transport of traffic beyond that
                   POP will be Focal's responsibility and at Focal's cost. If
                   Focal has more than one local switch in the same building,
                   the interconnection POI for all switches may be located in
                   the same physical space.

                   B3.2.1.4  Ameritech must Interconnect with Focal at a DS1
                   bandwidth. Focal may allow Interconnection at other
                   bandwidths where technically feasible and mutually agreeable
                   at termination charges to be agreed upon by the Parties. DS1
                   Collocation Termination charges apply for the use of space
                   provided for terminating Local Traffic and IntraLATA Toll
                   Traffic as specified in Exhibit PS-VII-A. If the facility is
                   terminated to Focal at a DS3 level, Ameritech must purchase
                   28 DS1 Collocation Termination charges and DS3 to DS1
                   multiplexing, from Focal.

           B3.2.2  Leasing Facilities from Focal. Under this method of
                   -----------------------------                    
           Interconnection, Ameritech may transport traffic to the designated
           POI in Focal's Wire Centers by using DS1 facilities furnished by
           Focal. Such facilities may be used by Ameritech solely for purposes
           of delivering Local Traffic and IntraLATA Toll Traffic originating in
           Ameritech's network for termination on Focal's local network. The POI
           will be established pursuant to the requirements of SECTION B3.2.1.3.
                                                               ----------------

                   B3.2.2.1  Leasing of Focal provided facilities may be used by
                   Ameritech as a: i) permanent method of Interconnection, ii)
                   an interim method of Interconnection if Ameritech does not
                   have sufficient capacity on its transport equipment in the
                   LEC Access space in Focal's Wire Center as described in
                   SECTION B3.2.3 or iii) in conjunction with Collocation as
                   --------------
                   described in SECTION B3.2.4.
                                --------------

                   B3.2.2.2  If Ameritech requests to lease Focal provided
                   facilities, Focal will determine the availability of DS1
                   transport capacity between Ameritech and

                                       7
<PAGE>
 
                   Focal in order to fulfill the Interconnection access request.
                   If capacity is available, Focal will notify Ameritech and
                   provide Connecting Facility Assignments (CFA). If DS1 
                   capacity is not available from Focal provided facilities,
                   Focal will notify Ameritech that Focal will not fulfill the
                   Interconnection access request. Focal will have no obligation
                   to add facilities to meet Ameritech's request.

                   B3.2.2.3  If Ameritech leases facilities from Focal, such
                   facilities will be provided pursuant to Focal's standard
                   terms and conditions for that service, except that the rates
                   specified in Exhibit PS-VII-A shall supersede the
                   corresponding rates in such standard terms and conditions.

                   B3.2.2.4  The standard interval for Focal provided
                   facilities is thirty-three (33) Business Days from the date
                   of receipt of Ameritech's ASR. However, the initial request
                   for Interconnection at an Focal Wire Center will be regarded
                   as a project and therefore require negotiated intervals on
                   an individual case basis.

            B3.2.3  Interim Leasing.  Focal will provide Ameritech a minimum of
                    ---------------                                         
            ninety (90) calendar days prior notification of its intention to
            begin accepting incoming traffic from Ameritech. If Ameritech elects
            to interconnect with Focal using the method described in SECTION
                                                                     -------
            B3.2.1 and does not have sufficient capacity on its transport
            ------
            equipment in the LEC Access space in Focal's Wire Center to meet the
            Interconnection traffic requirements, at either Party's request,
            Ameritech will use facilities leased from Focal.

                   B3.2.3.1  Interim facilities will be provided by Focal
                   pursuant to the requirements of SECTION B3.2.2, subject to
                                                   --------------
                   the following:

                         B3.2.3.1.1  If Ameritech is required to use Focal
                         provided DS1 facilities for an interim period,
                         Ameritech will pay Focal the nonrecurring charge and
                         the monthly recurring charge for these facilities,
                         subject to the discount described below.

                         B3.2.3.1.2  No discounts shall apply if the additional
                         equipment which Ameritech must install can be added to
                         existing bays in the space.

                         B3.2.3.1.3  If Ameritech requires the addition of a new
                         bay to complete Interconnection by Collocation, and
                         Focal gives Ameritech less than ninety (90) calendar
                         days advance notice of its intention to accept incoming
                         traffic, the DS1 rate will be reduced by 1/60 of the
                         monthly recurring, charge for each day less than such
                         ninety (90) calendar days of the notification of intent
                         to accept incoming traffic. The discounted rate will
                         only be applicable for a period of no longer

                                       8
<PAGE>
 
                         than 150 calendar days from the date Focal informed
                         Ameritech of its intention to accept incoming traffic.
                         At the 151st calendar day, the discounts will no
                         longer apply. Ameritech has the option to use these
                         facilities as a permanent method of Interconnection or
                         to transition to physical Collocation as a method of
                         Interconnection. If Ameritech opts to transition to
                         physical Collocation facilities, Focal will waive
                         additional non-recurring charges. If Ameritech elects
                         to keep leased facilities as a permanent method of
                         Interconnection, Focal will bill Ameritech for and
                         Ameritech will repay the discounts that had been
                         applied in the interim period.

           B3.2.4  Leasing in Conjunction with Physical Collocation. Ameritech
                   ------------------------------------------------
           may elect to combine Interconnection by Collocation as described in
           SECTION B3.2.1 with leasing facilities from Focal as described in
           -------------- 
           SECTION B3.2.2 by using the leased facilities to connect from an
           --------------
           intermediate point on the Focal network at which Ameritech is
           Collocated to the Focal Wire Center at which the designated POI is
           located. For example, the Focal End Office is Office A and Focal
           facility office is Office B. Ameritech may have capacity to terminate
           a facility at Focal Office B, but decides to lease a facility from
           Focal to get to the End Office A. In this scenario, both DS1 facility
           charges and charges for Focal space would apply.

           B3.2.5  Interconnection in Other ILEC Territories. In those instances
                   -----------------------------------------                  
           where Focal's POI is in an ILEC territory other than Ameritech's in
           a multi-jurisdictional LATA, Ameritech may interconnect using such
           other ILEC facilities for transporting Local Traffic and IntraLATA
           Toll Traffic to the designated POI in Focal's Wire Centers by using
           ILEC provided facilities which are terminated in ILEC's equipment
           located in the LEC Access Equipment Room in Focal's Wire Center used
           to provide total service access/5/ for Focal or in Focal provided
           equipment (when both Focal and the ILEC are located in the same
           building) on the same terms and conditions as specified in B.3.2.1.
                                                                      -------

           B3.2.6  Leasing Facilities From Third Parties.  In the future,
                   --------------------------------------              
           Ameritech may utilize Alternate Access Providers which are collocated
           in Focal Wire Centers to lease facilities for interconnecting with
           Focal for the termination of Ameritech's Local Traffic and IntraLATA
           Toll Traffic. Upon notification from Ameritech of its intent to
           utilize Alternate Access Provider facilities, Focal will provide
           applicable pricing to be agreed upon by the Parties.
                     

     C3.2  SS7 INTERCONNECTION.
           -------------------

____________________

/5/  Total service access are access services purchased by Focal from ILEC to
 -                                                                          
     provide switched or dedicated access to Focal Customers.

                                       9
<PAGE>
 
          C.3.2.1  Ameritech's Use of Focal Network. Focal's process for billing
                   --------------------------------                           
          Signaling Facility, Port and Message Usage is outlined below. For
          Common Channel Signaling (CCS) network usage dedicated to network
          Interconnection, Focal will apply its tariffed monthly recurring and
          non-recurring rates for Ports and Links used by Ameritech as well as a
          per message CCS call set-up charge. In the case of CCS network usage
          shared for exchange access and network interconnection purposes, Focal
          has developed a process for calculating a Percent Local Signaling 
          factor. In the course of exchanging traffic with Focal, Ameritech will
          utilize the Focal CCS network. This procedure will enable Focal to
          calculate a factor that will be applied to its tariffed recurring and
          non-recurring rates for Signaling Ports and Links, as well as to
          measure and apply a rate per CCS call set up message. Focal will bill
          Ameritech both pro-rated link facility and port charges based on a
          percentage factor and a per signaling message charge applied to each
          inbound call attempt. This usage bill will be based on Initial 
          Address Messages (IAM). Transaction Capabilities Application Part
          (TCAP) messages are not part of Focal's current service offering. If
          in the future Focal requires TCAP messages to be exchanged, the
          Parties will negotiate appropriate rates.

                   C.3.2.1.1  Signaling Facility and Port Billing Criteria for
                              -----------------------------------------------
                   Shared CCS Network Usage
                   ------------------------

                   Focal will initiate and maintain a process that will poll its
                   end offices switches to develop an aggregate collection of
                   inbound call attempts received from Ameritech. This number
                   will be used as a numerator in a formula to calculate a usage
                   percentage. Focal will also aggregate total originating and
                   terminating call attempts traversing all trunk groups between
                   Ameritech and Focal's end office switches. This number will
                   serve as the denominator. The percentage derived from this
                   process will be applied as a factor against Focal's tariffed
                   recurring and non-recurring rates for Signaling Links and
                   Ports.

                   TOTAL # CALL ATTEMPTS INBOUND LOCAL TRUNKS = % FACTOR
                   ------------------------------------------
                   TOTAL # IN & OUT CALL ATTEMPTS ON ALL TRUNKS

                   % FACTOR X FACILITY & PORT RATE = FIXED BILL

                   C3.2.1.2  Signaling Message Usage Billing
                             -------------------------------

                   Focal will also apply a per signaling message rate to the
                   total number of inbound call attempts as aggregated and
                   described above. This rate will represent the total number of
                   IAMs that are involved in the call set up process. See
                   example

                                       10
<PAGE>
 
                   TOTAL # CALL ATTEMPTS X IAM PER MESSAGE =USAGE BILL INBOUND 
                   LOCAL TRUNKS RATE

                   C3.2.1.3  Credits and Debits
                             ------------------ 

                   The percentage factor will be applied against Focal's
                   Signaling Facility and Port rates to create a prorated bill
                   that will be rendered to Ameritech for payment. Additionally,
                   Focal will include the per message usage total in the bill
                   rendered to Ameritech.

           C3.2.2  Focal's Use of Ameritech's Signaling.  For Common Channel
                   ------------------------------------
           Signaling (CCS) network usage dedicated to network interconnection,
           Focal will pay Ameritech on the same basis as it pays Ameritech for
           signaling associated with switched access until such time as (i)
           Ameritech implements a method to measure CCS usage associated with
           local traffic; or (ii) the Parties agree otherwise, or are ordered by
           any court, regulatory authority or other tribunal.

           C3.2.3  Each Party will bill in accordance with the methodology
           described above. However, neither Party agrees with the methodology
           described above for calculating and charging for signaling usage of
           the other Party. Therefore, a Party may challenge the methodology
           described above in accordance with the dispute resolution procedure
           of SECTION 28.3 and challenge the billing in accordance with its
              ------------                 
           rights under SECTION 28.2. If a different methodology is ordered by a
                        ------------      
           court, regulatory authority or other tribunal of such dispute,
           charges will be trued-up in accordance with the methodology for
           charging for CCS usage approved in such proceeding.

      3.3  FIBER-MEET.

           3.3.1   If the Parties Interconnect their networks pursuant to a
Fiber-Meet, the Parties shall jointly engineer and operate a single Synchronous
Optical Network ("SONET") transmission system. Unless otherwise mutually agreed,
this SONET transmission system shall be configured as illustrated in EXHIBIT A,
                                                                     ---------
and engineered, installed, and maintained as described in this ARTICLE III and
                                                               -----------
in the Plan (as defined in SECTION 8.1).
                           -----------

           3.3.2   Ameritech shall, wholly at its own expense, procure, install
and maintain Optical Line Terminating Multiplexor ("OLTM") equipment in the
Ameritech Interconnection Wire Center ("AIWC") identified for each LATA set
forth on SCHEDULE II.1, in capacity sufficient to provision and maintain all
         -------------                                                    
logical trunk groups prescribed by ARTICLES IV and V.
                                   -----------     -

           3.3.3   Focal shall, wholly at its own expense, procure, install and
maintain the OLTM equipment in the Focal Interconnection Wire Center ("FIWC")
identified for that LATA in SCHEDULE II.1, in capacity sufficient to provision
                            -------------                                   
and maintain all logical trunk groups prescribed by ARTICLES IV and V.
                                                    -----------     -

                                       11
<PAGE>
 
           3.4.3   Unless otherwise agreed by the Parties, the Parties shall
designate the Wire Center Focal has identified as its initial Routing Point in
the LATA as the FIWC in that LATA and shall designate the Ameritech Tandem
Office Wire Center within the LATA nearest to the FIWC (as measured in airline
miles utilizing the V&H coordinates method) as the AIWC in that LATA.

           3.4.4   The Interconnection Activation Date in each new LATA shall be
mutually established based on then-existing force and load, the scope and
complexity of the requested Interconnection and other relevant factors. The
Parties acknowledge that, as of the Effective Date, the average interval to
establish Interconnection via Collocation or Fiber-Meet is one hundred fifty
(150) days. Within ten (10) Business Days of Ameritech's receipt of Focal's
notice specified in SECTION 3.4.1, Ameritech and Focal shall confirm the AIWCs,
                    -------------                                           
the FIWCs and the Interconnection Activation Date for the new LATA by attaching
a supplementary schedule to SCHEDULE 2.1.
                            -------------

      3.5  ADDITIONAL INTERCONNECTION IN EXISTING LATAs.  If Focal deploys
additional switches in a LATA after the Effective Date, or otherwise wishes to
establish Interconnection with additional Ameritech Central Offices, Focal shall
be entitled, upon written notice thereof to Ameritech, to establish such
Interconnection and the terms and conditions of this Agreement shall apply to
such Interconnection. If Ameritech deploys additional switches in a LATA after
the Effective Date, or otherwise wishes to establish Interconnection with
additional Focal Central Offices, Ameritech shall be entitled, upon written
notice thereof to Focal, to establish such Interconnection and the terms and
conditions of this Agreement shall apply to such Interconnection. If either
Party establishes an additional Tandem Switch in a given LATA, the Parties shall
jointly determine the requirements regarding the establishment and maintenance
of separate trunk group connections and the sub-tending arrangements relating to
Tandem Switches and End Offices which serve the other Party's Customers within
the Exchange Areas served by such Tandem Switches.

      3.6  NONDISCRIMINATORY INTERCONNECTION. Interconnection shall be equal in
quality to that provided by the Parties to themselves or any subsidiary,
Affiliate or other person. For purposes of this SECTION 3.6, "EQUAL IN quality" 
                                                -----------      
means the same technical criteria and service standards that a Party uses within
its own network. If Focal requests an Interconnection that is of a different
quality than that provided by Ameritech to itself or any subsidiary, Affiliate
or other person, such request shall be treated as a Bona Fide Request and
established upon rates, terms and conditions consistent with the Act.

      3.7  NETWORK MANAGEMENT.

           3.7.1   Focal and Ameritech shall work cooperatively to install and
maintain a reliable network. Focal and Ameritech shall exchange appropriate
information (e.g., maintenance contact numbers, network information, information
             ----  
required to comply with law enforcement and other security agencies of the
government and such other information as the Parties shall mutually agree) to
achieve this desired reliability.

                                      13
<PAGE>
 
           3.7.2   Focal and Ameritech shall work cooperatively to apply sound
network management principles by invoking network management controls to
alleviate or to prevent congestion.

      3.8  STANDARDS OF PERFORMANCE.

           3.8.1   Each Party shall provide the other Party Interconnection (i)
in accordance with SECTION 3.6 as determined by this SECTION 3.8 and (ii) as
                   -----------                       -----------           
required by the Commission (collectively, the "INTERCONNECTION PERFORMANCE
BENCHMARKS").

           3.8.2   To determine a Party's compliance with the Interconnection
Performance Benchmarks, each Party shall maintain separate records of the
specific criteria listed on SCHEDULE 3.8 (each, an "INTERCONNECTION PERFORMANCE
                            ------------                                      
ACTIVITY") relating to Interconnection that it provides to itself, its
subsidiaries, and Affiliates (the "PROVIDING PARTY'S INTERCONNECTION RECORDS")
and to other LECs (the "OTHER LEC INTERCONNECTION RECORDS") and parallel
records of the Interconnection that the Providing Party provides to the other
Party (the "OTHER PARTY'S INTERCONNECTION RECORDS") and shall use the methods
described in SCHEDULE 3.8 to calculate Interconnection Performance Activity and
             ------------                                                
determine compliance with such Interconnection Performance Activity and with
such additional criteria to which the Parties may agree upon, including those
regarding Ameritech's compliance with different performance levels and intervals
requested by Focal and provided by Ameritech pursuant to SECTION 3.6 and a Bona
                                                         -----------
Fide Request.

           3.8.3   The Providing Party shall provide to the other Party for each
calendar month (a "REPORTING PERIOD"), by the twenty-second (22nd) day of the
following month, in a self-reporting format, the Providing Party's 
Interconnection Records, the Other LEC Interconnection Records and the Other 
Party's Interconnection Records so that the Parties can determine the Providing
Party's compliance with the Interconnection Performance Benchmarks If (i) the
Providing Party fails to comply with an Interconnection Performance Benchmark
with respect to an Interconnection Performance Activity for a Reporting Period.
(ii) the sample size of the Interconnection Performance Activity measured for
such Reporting Period is statistically valid and (iii) the amount by which the
applicable Interconnection Performance Activity deviates from the corresponding
Interconnection Performance Benchmark is statistically significant, then the
Providing Party shall have committed a "Specified Performance Breach".
Notwithstanding anything to the contrary in this SECTION 3.8, the Parties
                                                 ----------- 
acknowledge that (x) the Providing Party shall not be required to provide to the
other Party those Other LEC Interconnection Records that correspond to and
measure levels of quality and performance levels and intervals of
Interconnection that are requested by an Other LEC pursuant to 47 C.F.R. (S)5
1.305(a)(4); (y) the Other LEC Interconnection Records shall be provided to the
other Party on an aggregate basis and (z) such Other LEC Interconnection Records
shall be provided to the other Party in a manner that preserves the
confidentiality of each other LEC and any of such LEC's proprietary information
(including CPNI).

           3.8.4   In no event shall the Providing Party be deemed to have
committed a Specified Performance Breach if the Providing Party's failure to
meet or exceed an Interconnection Performance Activity is caused by a Delaying 
Event. If a Delaying Event (i) prevents the Providing

                                      14
<PAGE>
 
Party from performing a certain function or action that affects an
Interconnection Performance Activity, then such occurrence shall be excluded
from the calculation of such Interconnection Performance Activity and the
determination of the Providing Party's compliance with the applicable
Interconnection Performance Benchmark or (ii) only suspends the Providing
Party's ability to timely perform such Interconnection Performance Activity,
then the applicable time frame in which the Providing Party's compliance with
the Interconnection Performance Benchmark is measured shall be extended on a
like-time basis equal to the duration of such Delaying Event.

           3.8.5   Upon the occurrence of a Specified Performance Breach by the
Providing Party, the other Party may forego the dispute escalation procedures
set forth in SECTION 28.3 and (i) bring an action against the Providing Party in
             ------------                                                      
an appropriate Federal district court, (ii) file a complaint with the FCC
pursuant to Sections 207 or 208 of the Act, (iii) seek a declaratory ruling from
the FCC, (iv) file a complaint in accordance with the rules, guidelines and
regulations of the Commission or (v) seek other relief under Applicable Law.

           3.8.6   The other Party shall also be entitled to any Credit
Allowances pursuant to the same terms and conditions that the Providing Party
offers Credit Allowances to its Customers, including those described on SCHEDULE
                                                                        --------
10.9.6.
- ------

           3.8.7   The Parties' agreement to the procedures set forth in this
SECTION 3.8 shall not (i) relieve either Party of its obligations to perform
- -----------                                          
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the parity requirements of this Agreement and of the
Act have or have not been met.

3.9  9-1-1 SERVICE.

           3.9.1   Ameritech shall provide 9-1-1 Service to Focal as described
in this SECTION 3.9 in each Rate Center in which (i) Focal is authorized to
        -----------                                                       
provide local exchange services and (ii) Ameritech is the 9-1-1 service
provider.

           3.9.2   Service and Facilities Provided. 

           (a)     Ameritech will provide Focal with multiplexing at a
                   designated Ameritech Central Office at the rates set forth at
                   Item I of the Pricing Schedule and pursuant to the terms and
                   conditions in applicable tariffs. Ameritech will also provide
                   Focal with trunking from the Ameritech Central Office to the
                   designated Ameritech Control Office(s) with sufficient
                   capacity to route Focal's originating 9-1-1 calls over
                   Service Lines to the designated primary PSAP or to designated
                   alternate locations. Such trunking will be provided at the
                   rates set forth at Item I of the Pricing Schedule. If Focal
                   forwards the ANI information of the calling party to the
                   Control Office, Ameritech will forward that calling number
                   and the associated street address to the PSAP for display. If
                   no ANI is forwarded by Focal, Ameritech will display a
                   Central Office identification code for display at the PSAP.

                                      15
<PAGE>
 
           (b)     Focal will provide the necessary trunking to route
                   originating 9-1-1 traffic from Focal's End Office(s) to the
                   Ameritech Control Office(s). The points of Interconnection
                   for primary and diverse routes are identified at SECTION 2 of
                                                                    ---------
                   SCHEDULE 3.9. Focal may, at its option, acquire such
                   ------------
                   trunking from Ameritech at rates, terms and conditions
                   provided in Ameritech's tariffs.

           (c)     Ameritech will provide to Focal, in paper or mechanized
                   format, an address and routing file that will specify which
                   9-1-1 Control Office serves as the jurisdictional 9-1-1
                   answering point for Customers within the Exchange Areas
                   served by Focal. The address and routing file will be
                   provided by exchange rate center or community upon request. A
                   specified charge as set forth at Item I of the Pricing 
                   Schedule will apply per request. Until such time as a
                   mechanized process for provision of this information is made
                   available by Ameritech and, at intervals determined by
                   Ameritech, Ameritech shall provide to Focal in a paper format
                   any updates to the address and routing file.

           (d)     Ameritech will coordinate access to the Ameritech ALI
                   database for the initial loading and updating of Focal
                   Customer information. Access coordination will include:

                   (1)   Ameritech provided format requirements and a delivery
                         address for Focal to supply an electronic version of
                         Customer telephone numbers, addresses and other
                         information both for the initial load and, where
                         applicable, daily updates. Ameritech shall confirm
                         receipt of this data as described in SECTION
                                                              -------    
                         III.9.2(h);
                         ----------

                   (2)   Coordination of error resolution involving entry and
                         update activity;

                   (3)   Provisioning of specific 9-1-1 routing information on
                         each access line;

                   (4)   Updating the Ameritech ALI database from paper records
                         of service order activity supplied by Focal is
                         optional. The charge for this service is separate and
                         set forth at Item I of the Pricing Schedule under the
                         category "Optional Manual Update"; and

                   (5)   Providing Focal with reference data required to ensure
                         that Focal's Customer will be routed to the correct
                         Control Office when originating a 9-1-1 call.

           (e)     Focal shall pay Ameritech a one-time charge as set forth at
                   Item I of the Pricing Schedule per 9-1-1 Control Office
                   trunk group (the "9-1-1 CONTROL OFFICE SOFTWARE ENHANCEMENT
                   CONNECTION CHARGE"). Although the services offered in this
                   Agreement and the charges set forth at Item I of the

                                      16
<PAGE>
 
                   Pricing Schedule contemplate that each NXX will reside in a
                   single Control Office, Focal may, at its sole option, 
                   designate that an NXX shall reside in more than one 9-1-1 
                   Control Office.
 
          (f)     In the event of an Ameritech or Focal 9-1-1 trunk group
                   failure, the Party that owns the trunk group will notify, on
                   a priority basis, the other Party of such failure, which
                   notification shall occur within two (2) hours of the
                   occurrence or sooner if required under Applicable Law. The
                   Parties will exchange a list containing the names and
                   telephone numbers of the support center personnel responsible
                   for maintaining the 9-1-1 Service between the Parties.

           (g)     Ameritech will provide the order number and circuit
                   identification code in advance of the service due date.

           (h)     Focal or its third party agent will provide CNA data to
                   Ameritech for use in entering the data into the 9-1-1
                   database. The initial CNA data will be provided to Ameritech
                   in a format prescribed by Ameritech. Focal is responsible for
                   providing Ameritech updates to the CNA data and error
                   corrections which may occur during the entry of CNA data to
                   the Ameritech 9-1-1 Database System. Focal shall reimburse
                   Ameritech for any additional database charges incurred by
                   Ameritech for errors in CNA data updates caused by Focal or
                   its third party agent. Ameritech will confirm receipt of
                   such data and corrections by the next Business Day by 
                   providing Focal with a report of the number of items sent, 
                   the number of items entered correctly, and the number of
                   errors.

           (i)     Focal will monitor the 9-1-1 circuits for the purpose of
                   determining originating network traffic volumes. Focal will
                   notify Ameritech if the traffic study information indicates
                   that additional circuits are required to meet the current
                   level of 9-1-1 call volumes.

           (j)     Incoming trunks for 9-1-1 shall be engineered to assure
                   minimum P.01 grade of service as measured using the "busy
                   day/busy hour" criteria.

           3.9.3   Compensation.

           In addition to the amounts specified in SECTION III.9.2, Focal shall
                                                   ---------------
compensate Ameritech as set forth at Item I of the Pricing Schedule.

           3.9.4   Additional Limitations of Liability Applicable to 9-1-1
Service.

           (a)     Ameritech is not liable for the accuracy and content of CNA
                   data that Focal delivers to Ameritech. Focal is responsible
                   for maintaining the accuracy and content of that data as
                   delivered.

                                      17
<PAGE>
 
           (b)     Notwithstanding anything to the contrary contained herein,
                   Ameritech's liability to Focal and any third person shall be
                   limited to the maximum extent permitted by Mich. Comp. Laws
                   Section 484.1604.

                                  ARTICLE IV
                TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE
                 SERVICE TRAFFIC PURSUANT TO SECTION 251(c)(2)
                                        
      4.1  SCOPE OF TRAFFIC.  ARTICLE IV prescribes parameters for trunk groups
                              ----------                                        
(the "LOCAL/INTRALATA TRUNKS") to be effected over the Interconnections
specified in ARTICLE III for the transmission and routing of Local Traffic and
             -----------
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

      4.2  LIMITATIONS. No Party shall terminate Exchange Access traffic or
originate untranslated 800/888 traffic over Local/IntraLATA Interconnection
Trunks.

      4.3  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING.

The Parties shall jointly engineer and configure Local/IntraLATA Trunks over
the physical Interconnection arrangements as follows:

           4.3.1   Each Party shall initially configure either a one (1)-or a
two (2)-way trunk group as a direct transmission path between each FIWC and
AIWC.

           4.3.2   Notwithstanding anything to the contrary contained in this
ARTICLE IV, if the traffic volumes between any two (2) Central Office Switches 
- ----------
at any time exceeds the CCS busy hour equivalent of one (1) DS1, the Parties
shall, within sixty (60) days after such occurrence, establish new direct trunk
groups to the applicable End Office(s) consistent with the grades of service and
quality parameters set forth in the Plan.

           4.3.3   Only those valid NXX codes served by an End Office may be
accessed through a direct connection to that End Office.

           4.3.4   Each Party shall ensure that each Tandem connection permits
the completion of traffic to all End Offices which sub-tend that Tandem.
Pursuant to ARTICLE V, each Party shall establish and maintain separate trunk
            ---------
groups connected to each Tandem of the other Party which serves, or is sub-
tended by End Offices which serve, such other Party's Customers within the
Exchange Areas served by such Tandem Switches.

           4.3.5   Each Party shall, upon request of the other Party, provision,
within thirty (30) days of such request, additional trunks for use in a pre-
existing Interconnection arrangement, subject to SECTION 19.12. of this
                                                 -------------       
Agreement.

                                      18
<PAGE>
 
      4.4  SIGNALING.

Signaling Interconnection may be used for signaling between Focal switches,
between Focal switches and Ameritech switches, and between Focal switches and
those third party networks with which Ameritech's SS7 network is interconnected.

           4.4.1   Where available, Common Channel Interoffice Signaling (CCIS)
signaling shall be used by the Parties to set up calls between the Parties'
Telephone Exchange Service networks. Each Party shall supply Calling Party
Number (CPN) within the SS7 signaling message, if available. If CCIS is
unavailable, Multi-Frequency (MF) signaling shall be used by the Parties. Each
Party shall charge the other Party equal and reciprocal rates for CCIS signaling
at the rates set forth at Item V of the Pricing Schedule.

           4.4.2   Each Party is responsible for requesting Interconnection to
the other Party's CCIS network, where SS7 signaling on the trunk group(s) is
desired. Each Party shall connect to a pair of access STPs that serve each LATA
where traffic will be exchanged or shall arrange for signaling connectivity
through a third party provider which is connected to the other Party's signaling
network. The Parties shall establish Interconnection at the STP.

           4.4.3   The Parties will cooperate on the exchange of Transactional
Capabilities Application Part (TCAP) messages to facilitate interoperability of
CCIS-based features between their respective networks, including all CLASS
features and functions, to the extent each Party offers such features and
functions to its Customers. All CCIS signaling parameters will be provided,
including Calling Party Number (CPN), Originating Line Information (OLI),
calling party category and charge number. For terminating Exchange Access
traffic, such information shall be passed by a Party to the extent that such
information is provided to such Party.

           4.4.4   Where available and upon the request of the other Party, each
Party shall cooperate to ensure that its trunk groups are configured utilizing
the B8ZS ESF protocol for 64 Kbps clear channel transmission to allow for ISDN
interoperability between the Parties' respective networks.

      4.5  GRADES OF SERVICE.

The Parties shall initially engineer and shall jointly monitor and enhance all
trunk groups consistent with the Plan.

      4.6  MEASUREMENT AND BILLING.

           4.6.1   For billing purposes, each Party shall pass Calling Party
Number (CPN) information on each call that it originates over the
Local/IntraLATA Trunks; provided that all calls exchanged without CPN 
                        --------    
information shall be billed as either Local Traffic or IntraLATA Toll Traffic
based upon a percentage of local usage (PLU) factor calculated based on the
amount of actual volume during the preceding three (3) months. The PLU will be
reevaluated every three (3)

                                      19
<PAGE>
 
months. If either Party fails to pass at least ninety percent (90%) of calls
with CPN that it originates within a monthly billing period, then either Party
may require that separate trunk groups for Local Traffic and IntraLATA Toll
Traffic be established.

           4.6.2   Measurement of Telecommunications traffic billed hereunder
shall be (i) in actual conversation time as specified in FCC terminating FGD
Switched access tariffs for Local Traffic and (ii) in accordance with applicable
tariffs for all other types of Telecommunications traffic.

           4.6.3   On an interim basis, until such time as the Parties may
agree otherwise, or ordered by any court, regulatory authority or other
tribunal of any dispute, for the method of Interconnection described in SECTION
                                                                        -------
A.3.2, Focal will route IntraLATA Toll Traffic and Local Traffic associated with
- -----
an Ameritech-assigned Calling Party Number (CPN) and originating with Focal and
terminating with a Local Exchange Carrier other than Ameritech through Focal's
switched access trunks and will pay applicable access charges for such traffic
until such time that either (a) Focal is able to deliver a Calling Party Number
associated with an Focal LERG assigned number, or (b) the Customer's telephone
number has been ported to Focal using either Interim or Permanent Number
Portability. In the latter case, Focal shall provide to Ameritech at least
thirty 30 days' prior written notice of its intent to reroute this traffic over
the Interconnection trunks. Focal's agreement to route transit traffic as
described above shall not preclude Focal from asserting a contrary position
before any court, regulatory authority or other tribunal of any dispute.

      4.7  RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

           4.7.1   Reciprocal Compensation applies for transport and termination
of Local Traffic billable by Ameritech or Focal which a Telephone Exchange
Service Customer originates on Ameritech's or Focal's network for termination on
the other Party's network./6/ The Parties shall compensate each other for such
                           -
transport and termination of Local Traffic at the rate provided at Item II of
the Pricing Schedule.

           4.7.2   The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all IntraLATA Toll Traffic shall continue to be
governed by the terms and conditions of the applicable federal and state
tariffs.


________________________

/6/   Ameritech maintains that it was not Ameritech's intention in entering into
 -
      the Teligent Agreement, the AT&T Agreement or this Agreement that the
      Parties pay each other Reciprocal Compensation for traffic routed through
      or to Internet Service Providers (including, internet traffic). However,
      it is Focal's position that the Teligent Agreement and AT&T Agreement
      required the Parties to pay each other Reciprocal compensation for traffic
      routed through or to Internet Services Providers (including, internet
      traffic) and, by virtue of Focal's adoption of the Teligent Agreement
      under Section 252(i) of the Act, the same obligation applies under this
      Agreement.

                                      20
<PAGE>
 
           4.7.3   Each Party shall charge the other Party its effective
applicable federal and state tariffed intraLATA FGD switched access rates for
the transport and termination of all IntraLATA Toll Traffic.

           4.7.4   Compensation for transport and termination of all traffic
which has been subject to performance of INP by one Party for the other Party
pursuant to ARTICLE XIII shall be as specified in SECTION 13.7.
            ------------                          ------------

                                   ARTICLE V
                     TRANSMISSION AND ROUTING OF EXCHANGE
                     ACCESS TRAFFIC PURSUANT TO 251(C)(2)
                                        
      5.1  SCOPE OF TRAFFIC.  ARTICLE V prescribes parameters for certain trunk
                              --------                                        
groups ("ACCESS TOLL CONNECTING TRUNKS") to be established over the
Interconnections specified in ARTICLE III for the transmission and routing of
                              -----------                                    
Exchange Access traffic and nontranslated 800 traffic between Focal Telephone
Exchange Service Customers and Interexchange Carriers. Compensation for such
Exchange Access traffic is provided for in ARTICLE VI.
                                           ----------

      5.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING.

           5.2.1   The Parties shall jointly establish Access Toll Connecting
Trunks by which they will jointly provide Tandem-transported Switched Exchange
Access Services to Interexchange Carriers to enable such Interexchange Carriers
to originate and terminate traffic from and to Focal's Customers.

           5.2.2   Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access and nontranslated 800/888 traffic
to allow Focal's Customers to connect to or be connected to the interexchange
trunks of any Interexchange Carrier which is connected to an Ameritech access
Tandem.

           5.2.3   The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch that Focal utilizes to provide Telephone
Exchange Service and Switched Exchange Access Service in a given LATA to an
access Tandem Switch Ameritech utilizes to provide Exchange Access in such LATA.

           5.2.4   In each LATA identified on SCHEDULE 2.1, each Focal End
                                              ------------
Office Switch in that LATA shall subtend each Ameritech access Tandem in that 
LATA.

           5.2.5   Only those valid NXX codes served by an End Office may be
accessed through a direct connection to that End Office.

                                      21
<PAGE>
 
                                  ARTICLE VI
                        MEET-POINT BILLING ARRANGEMENTS
                                        
      6.1  MEET-POINT BILLING SERVICES.

           6.1.1  Pursuant to the procedures described in Multiple Exchange
Carrier Access Billing ("MECAB") document SR-BDS-000983, issue 5, June 1994,
the Parties shall provide to each other the Switched Access Detail Usage Data
and the Switched Access Summary Usage Data to bill for jointly provided switched
access service such as switched access Feature Groups B and D. The Parties agree
to provide this data to each other at no charge. If the procedures in the
MECAB document are amended or modified, the Parties shall implement such amended
or modified procedures within a reasonable period of time.

           6.1.2  Focal shall designate access Tandems or any other reasonable
facilities or points of Interconnection for the purpose of originating or
terminating IXC traffic. For each such access Tandem designated, the Parties
shall mutually agree upon a billing percentage as set forth on SCHEDULE 6.0 and
                                                               ------------  
shall further agree, within thirty (30) days of the Effective Date, /7/ upon
                                                                     -
billing percentages for additional routes, which billing percentages shall
be set forth in SCHEDULE 6.0 as amendments hereto. Either Party may make this
                ------------                                                    
billing percentage information available to IXCs. The billing percentages shall
be calculated according to one of the methodologies specified for such purposes
in the MECAB document.

           6.1.3  The Parties shall undertake all reasonable measures to ensure
that the billing percentage and associated information are maintained in
their respective federal and state access tariffs, as required, until such time
as such information can be included in the National Exchange Association
("NECA") FCC Tariff No. 4. Focal shall use its best efforts to include in such
tariff the billing percentage and associated information as a non-member of
NECA.

           6.1.4  Each Party shall implement the "MULTIPLE BILL/SINGLE TARIFF"
option in order to bill the IXC for each Party's own portion of jointly provided
Telecommunications Service.

      6.2  DATA FORMAT AND DATA TRANSFER.

           6.2.1  Necessary billing information will be exchanged on magnetic
tape or via electronic data transfer (when available) using the EMR format. The
Parties shall agree to a fixed billing period in the Implementation Plan.


______________________

/7/   Since the terms of this Agreement are the result of Focal's adoption under
 -
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 6.1.2, shall
                                                           ------------- 
      mean February 10, 1999.

                                      22
<PAGE>
 
           6.2.2  Focal shall provide to Ameritech, on a monthly basis, the
Switched Access Summary Usage Data (category 1150XX records) on magnetic tape
or, when available, via electronic data transfer using the EMR format.

           6.2.3  Ameritech shall provide to Focal, on a daily basis, the
Switched Access Detail Usage Data (category 1101XX records) on magnetic tape
no later than fourteen (14) days from the usage recording date. Ameritech shall
provide the information on magnetic tape or, when available, via electronic
data transfer (e.g., network data mover), using EMR format. Ameritech and
               ----
Focal shall use best efforts to utilize electronic data transfer.

           6.2.4  Each Party shall coordinate and exchange the billing account
reference ("BAR") and billing account cross reference ("BACR") numbers for the
Meet-Point Billing service. Each Party shall notify the other Party if the level
of billing or other BAR/BACR elements change, resulting in a new BAR/BACR
number.

      6.3  ERRORS OR LOSS OF ACCESS USAGE DATA.

           6.3.1 Errors may be discovered by Focal, the IXC or Ameritech. Each
Party agrees to use reasonable efforts to provide the other Party with 
notification of any discovered errors within two (2) Business Days of such 
discovery. All claims by a Party relating to errors or loss of access
usage data shall be made within thirty (30) calendar days from the date such
usage data was provided to that Party.

           6.3.2 In the event of a loss of data, both Parties shall cooperate
to reconstruct the lost data. If such reconstruction is not possible, the
Parties shall use a reasonable estimate of the lost data, based on twelve (12)
months of prior usage data; provided that if twelve (12) months of prior usage
                            --------
data is not available, the Parties shall base the estimate on as much prior
usage data that is available; provided, however, that if reconstruction is
                              --------  -------
required prior to the availability of at least three (3) months of prior usage
data, the Parties shall defer such reconstruction until three (3) months of
prior usage data is available.

      6.4  PAYMENT. The Parties shall not charge one another for the services
rendered pursuant to this ARTICLE V1.
                          -----------

      6.5  ADDITIONAL LIMITATIONS OF LIABILITY APPLICABLE TO MEET-POINT BILLING
ARRANGEMENTS.  In addition to the limitations of liability set forth in ARTICLE 
                                                                        -------
XXV1 and elsewhere in this Agreement, the following limitations on liability
- ----
shall apply with respect to the Meet-Point Billing arrangements described in 
this ARTICLE V1:
     ----------

           6.5.1  In the event of errors, omissions, or inaccuracies in data
received from either Party, the liability of the Party providing such data shall
be limited only to the provision of corrected data only. If data is lost, such
providing Party will develop a substitute based on past usage, as set forth in
SECTION 6.3.2.
- --------------

                                      23
<PAGE>
 
           6.5.2  In recognition that neither Party is being compensated for
services rendered under this ARTICLE V1, in no event shall a Party's liability
                             ---------- 
to the other Party for any Loss relating to or arising out of any act(s) or
omission(s) in its performance of its obligations under this ARTICLE VI exceed
                                                             ----------  
$10,000 in any one (1) month period.

                                  ARTICLE VII
                           TRANSPORT AND TERMINATION
                           OF OTHER TYPES OF TRAFFIC
                                        
     7.1  INFORMATION SERVICES TRAFFIC.

          7.1.1 Each Party shall route Information Service Traffic which
originates on its own network to the appropriate information services
platform(s) connected to the other Party's network over the Local/IntraLATA
Trunks.

          7.1.2 The Party ("ORIGINATING PARTY") on whose network the
Information Services Traffic originated shall provide an electronic file
transfer or monthly magnetic tape containing recorded call detail information to
the Party ("TERMINATING PARTY") to whose information platform the Information
Services Traffic terminated.

          7.13 In accordance with procedures to be established by the
Implementation Team, the Terminating Party shall provide to the Originating
Party via electronic file transfer or magnetic tape all necessary information to
rate the Information Services Traffic to the Originating Party's Customers and
establish uncollectible reserves pursuant to the Terminating Party's agreements
with each information provider.

          7.1.4 The Originating Party shall bill and collect such information
provider charges and remit the amounts collected to the Terminating Party less:

           (a)  The Information Services Billing and Collection fee set forth at
                Item III of the Pricing Schedule; and

           (b)  An uncollectibles reserve calculated based on the uncollectibles
                reserve in the Terminating Party's billing and collection
                agreement with the applicable information provider; and

           (c)  Customer adjustments provided by the Originating Party.

The Originating Party shall provide to the Terminating Party sufficient
information regarding uncollectibles and Customer adjustments. The Terminating
Party shall pass through the adjustments to the information provider. Final
resolution regarding all disputed adjustments shall be solely, between the
Originating Party and the information provider.

                                      24
<PAGE>
 
          7.1.5 Nothing in this Agreement shall restrict either Party from
offering to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

     7.2  BLV/BLVI TRAFFIC.

          7.2.1 Busy Line Verification ("BLV") is performed when one Party's
Customer requests assistance from the operator bureau to determine if the called
line is in use; provided, however, the operator bureau will not complete the
                --------  -------                                         
call for the Customer initiating the BLV inquiry. Only one BLV attempt will be
made per Customer operator bureau call.

          7.2.2 Busy Line Verification Interrupt ("BLVI") is performed when one
Party's operator bureau interrupts a telephone call in progress after BLV has
occurred. The operator bureau will interrupt the busy line and inform the called
party that there is a call waiting. The operator bureau will only interrupt the
call and will not complete the telephone call of the Customer initiating the
BLVI request. The operator bureau will make only one BLVI attempt per Customer
operator telephone call and the applicable charge applies whether or not
the called party releases the line.

          7.2.3 Each Party's operator bureau shall accept BLV and BLVI
inquiries from the operator bureau of the other Party in order to allow  
transparent provision of BLV/BLVI Traffic between the Parties' networks. Each
Party shall route BLV/BLVI Traffic inquiries over separate direct trunks (and
not the Local/IntraLATA Trunks) established between the Parties' respective
operator bureaus. Unless otherwise mutually agreed, the Parties shall configure
BLV/BLVI trunks over the Interconnection architecture defined in ARTICLE III,
                                                                 ----------- 
consistent with the Plan.

          7.2.4 Each Party shall compensate the other Party for BLV/BLVI
Traffic as set forth at Item IV of the Pricing Schedule.

      7.3 TRANSIT SERVICE.

          7.3.1 Ameritech shall provide Focal Transit Service as provided in
this SECTION 7.3.
     -----------

          7.3.2 "TRANSIT SERVICE" means the delivery of certain traffic between
Focal and a third party LEC or CMRS provider by Ameritech over the
Local/IntraLATA Trunks. Transit Service shall be provided only at Ameritech's
Tandem Switches, and not at any Ameritech End Office. The following traffic
types will be delivered: (i) Local Traffic and IntraLATA Toll Traffic originated
from Focal to such third party LEC or CMRS provider and (ii) IntraLATA Toll
Traffic orginated from such third party LEC and terminated to Focal where
Ameritech carries such traffic pursuant to the Commission's primary toll carrier
("PTC") plan or other similar plan.

                                      25
<PAGE>
 
           7.3.3 The Parties shall compensate each other for Transit Service
as follows:

           (a)   For Local Traffic and IntraLATA Toll Traffic originating from
                 Focal that is delivered over the Transit Service ("TRANSIT
                 TRAFFIC"):

                 (1)  Focal shall:

                      (A) Pay to Ameritech a Transit Service charge as set forth
                          at Item V of the Pricing Schedule; and

                      (B) Reimburse Ameritech for any charges, including
                          switched access charges, that a third party LEC or
                          CMRS provider with whom Ameritech does not have a
                          Transit Service agreement similar to that set forth
                          in this SECTION 7.3 imposes or levies on Ameritech for
                                  -----------
                          delivery or termination of any such Transit Traffic.

                 (2)  Ameritech shall remit to Focal any access charges
                      Ameritech receives from such third party LEC or CMRS
                      provider in connection with the delivery of such Transit
                      Traffic.

           (b)   For Local Traffic and IntraLATA Toll Traffic that is to be
                 terminated to Focal from a third party LEC or CMRS provider (i)
                 that is not subject to PTC arrangements (regardless of whether
                 Ameritech is the PTC) and (ii) Ameritech has a transiting
                 arrangement with such third party LEC or CMRS provider which
                 authorizes Ameritech to deliver such traffic to Focal ("OTHER
                 PARTY TRANSIT AGREEMENT"), then Ameritech shall deliver such
                 Local Traffic and IntraLATA Toll Traffic to Focal in accordance
                 with the terms and conditions of such Other Party Transit
                 Agreement and such third party LEC or CMRS provider (and not
                 Focal) shall be responsible to pay Ameritech the applicable
                 Transit Service charge.

           (c)   For IntraLATA Toll Traffic which is subject to a PTC
                 arrangement and where Ameritech is the PTC, Ameritech shall
                 deliver such IntraLATA Toll Traffic to or from Focal in
                 accordance with the terms and conditions of such PTC
                 arrangement.

          7.3.4  While the Parties agree that it is the responsibility of each
third party LEC or CMRS provider to enter into arrangements to deliver Local
Traffic and IntraLATA Toll Traffic to Focal, they acknowledge that such
arrangements are not currently in place and an interim arrangement is necessary
to ensure traffic completion. Accordingly, until the earlier of (i) the date on
which either Party has entered into an arrangement with such third party LEC or
CMRS provider to deliver Local Traffic and IntraLATA Toll Traffic to Focal and
(ii) the termination of this Agreement, Ameritech will provide Focal with
Transit Service.

                                      26
<PAGE>
 
            7.3.5 Ameritech expects that all networks involved in transit
 traffic will deliver each call to each involved network with CCIS and the
 appropriate Transactional Capabilities Application Part ("TCAP") message to
 facilitate full interoperability and billing functions and, to the extent such
 CCIS and TCAP messages are delivered by the originating third party LEC or
 CMRS provider, Ameritech will deliver such information to the terminating
 third party LEC or CMRS provider. In all cases, Focal is responsible to follow
 the Exchange Message Record ("EMR") standard and exchange records with both
 Ameritech and the terminating LEC or CMRS provider to facilitate the billing
 process to the originating network.

            7.3.6 For purposes of this SECTION VII.3, Ameritech agrees that it
                                       -------------               
shall make available to Focal, at Focal's sole option, any transiting
arrangement Ameritech's offers to another LEC at the same rates, terms and
conditions provided to such other LEC.

                                 ARTICLE VIII
                 INSTALLATION, MAINTENANCE, TESTING AND REPAIR
                                        
      8.1   PLAN. Within ninety (90) days after the Effective Date, /8/ Focal 
                                                                     -
and Ameritech shall joint1y develop a plan (the "PLAN") which shall define and
detail:

            (a) standards to ensure that Interconnection trunk groups experience
                a grade of service, availability and quality in accordance with
                all appropriate relevant industry-accepted quality, reliability
                and availability standards and in accordance with the levels
                identified in SECTION 3.6;
                              -----------

            (b) the respective duties and responsibilities of the Parties with
                respect to the administration and maintenance of the
                Interconnections (including signaling) specified in ARTICLE III
                                                                    -----------
                and the trunk groups specified in ARTICLES IV and V, including
                                                  -----------     -
                standards and procedures for notification and discoveries of
                trunk disconnects;

            (c) disaster recovery and escalation provisions; and

            (d) such other matters as the Parties may agree.

   
      8.2   OPERATION AND MAINTENANCE. Each Party shall be solely responsible 
for the installation, operation and maintenance of equipment and facilities
provided by it for Interconnection, subject to compatibility and cooperative
testing and monitoring and the specific operation and maintenance provisions
for equipment and facilities used to provide Interconnection.


_______________________

/8/   Since the terms of this Agreement are the result of Focal's adoption under
 -
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 8.1, shall
                                                           -----------
      mean February 10, 1999.
      
                                      27
<PAGE>
 
Operation and maintenance of equipment in Virtual Collocation shall be in
accordance with the provisions of ARTICLE XII.
                                  -----------

      8.3  INSTALLATION, MAINTENANCE, TESTING AND REPAIR. The intervals for
installations, maintenance, joint testing, and repair of its facilities and
services associated with or used in conjunction with Interconnection will be
determined in accordance with the requirements of SECTION 3.8.
                                                  -----------
               
      8.4  ADDITIONAL TERMS. Additional terms regarding the installation,
maintenance, testing and repair of equipment and facilities used for
Interconnection shall be as set forth in the Implementation Plan.


                                  ARTICLE IX
                     UNBUNDLED ACCESS -- SECTION 251(C)(3)
                                        
      9.1  ACCESS TO NETWORK ELEMENTS.

           9.1.1 Ameritech shall provide Focal access to Ameritech's Network
Elements on an unbundled basis at any technically feasible point in accordance
with the terms and conditions of this ARTICLE IX and the requirements of the 
                                      ----------                    
Act. Ameritech shall provide Focal access to each unbundled Network Element,
along with all of such unbundled Network Element's features, functions, and
capabilities in accordance with the terms and conditions of ARTICLE II and as
                                                            ---------- 
required by the Act, in a manner that shall allow Focal to provide any
Telecommunications Service that can be offered by means of that Network Element;
provided that the use of such Network Element is consistent with the Act.
- --------

          9.1.2  Notwithstanding anything to the contrary in this ARTICLE IX,
                                                                  ----------
Ameritech shall not be required to provide Network Elements beyond those
identified in 47 C.F.R. (S) 51.319 to Focal if:

          (1)    The Commission concludes that:


                 (A) such Network Element is proprietary or contains proprietary
                     information that will be revealed if such Network Element
                     is provided to Focal on an unbundled basis; and

                 (B) Focal could offer the same proposed Telecommunications
                     Service through the use of other, nonproprietary Network
                     Elements within Ameritech's network; or

          (2)    The Commission concludes that the failure of Ameritech to
                 provide access to such Network Element would not decrease the
                 quality of, and would not increase the financial or
                 administrative cost of, the Telecommunications

                                      28
<PAGE>
 
                 Service Focal seeks to offer, compared with providing that
                 service over other unbundled Network Elements in Ameritech's
                 network.

          9.1.3  Ameritech shall be required to make available Network Elements
only where such Network Elements, including facilities and software necessary
to provide such Network Elements, are available. If Ameritech makes available
Network Elements that require special construction, Focal shall pay to Ameritech
any applicable special construction charges.

     9.2  NETWORK ELEMENTS /9/.  At the request of Focal, Ameritech shall
                            -
provide Focal access to the following Network Elements on an unbundled basis:

          9.2.1  Local Loops, as more fully described on SCHEDULE 9.2.1;
                                                         --------------

          9.2.2  The Network Interface Device, as more fully described on
SCHEDULE 9.2.2;
- --------------

          9.2.3  Switching Capability, as more fully described on SCHEDULE 
                                                                  --------
9.2.3;
- -----

          9.2.4  Interoffice Transmission Facilities, as more fully described on
SCHEDULE 9.2.4;
- --------------

          9.2.5  Signaling Links and Call-Related Databases, as more fully 
described on SCHEDULE 9.2.5;
             --------------

          9.2.6  Operations Support Systems ("OSS") functions, to be used in
conjunction with other Network Elements, as more fully described on SCHEDULE   
                                                                    --------
9.2.6; and
- -----

          9.2.7  Operator Services and Directory Assistance, as more fully 
described on SCHEDULE 9.2.7.
             --------------

     9.3  COMBINATION OF NETWORK ELEMENTS.

          9.3.1  Ameritech shall provide Network Elements to Focal in a manner
that shall allow Focal to combine such Network Elements (a "Combination") in
order to provide a Telecommunications Service. When purchasing a Combination,
Focal will have access to all features and capabilities of each individual
Network Element that comprises such Combination and the specific technical and
interface requirements for each of the Network Elements shall apply, 


- ----------------------

/9/  Notwithstanding anything contrary in this Agreement, in the event the FCC
 -
     or a court of competent jurisdiction determines that incumbent local
     exchange carrier(s) generally are not required and/or Ameritech is not
     required to make available one or more Network Element(s) provided by
     Ameritech under this Agreement, Ameritech shall have the right to
     immediately delete such Network Element(s) and the provisions related
     thereto contained in this Agreement.

                                      29
<PAGE>
 
except to the extent not technically feasible given the specific manner in which
Focal has requested that the elements be combined.

          9.3.2 Except upon the request of Focal, Ameritech shall provide
Network Elements separately from each other, and shall not separate Network
Elements it normally provides in combination into separate Network Elements.

          9.3.3 Upon Focal's request, Ameritech shall perform the functions
necessary to combine Ameritech's Network Elements in any manner, even if those
elements are not ordinarily combined in Ameritech's network; provided that such
                                                             --------         
combination is (i) technically feasible and (ii) would not impair the ability of
other Telecommunications Carriers to obtain access to unbundled Network Elements
or to Interconnect with Ameritech's network. In addition, upon a request of
Focal that is consistent with the above criteria, Ameritech shall perform the
functions necessary to combine Ameritech's Network Elements with elements
possessed by Focal in any technically feasible manner to allow Focal to provide
a Telecommunications Service.

          9.3.4 Ameritech shall make available to Focal the following
Combinations at the rates set forth at Item V of the Pricing Schedule:
                                              
                9.3.4.1  Unbundled Element Platform with Operator Services and
                         Directory Assistance. This Combination is described on
                         SCHEDULE 9.3.4.
                         --------------

                9.3.4.2  Loop Combination. This Combination is described on 
                         SCHEDULE 9.3.4.
                         --------------

                9.3.4.3  Switching Combination #1. This Combination is described
                         on SCHEDULE 9.3.4.
                            --------------  

          9.3.5 The following Network Elements and Combinations shall be 
requested by Focal in accordance with SECTION 9.6:
                                      -----------

                9.3.5.1  Unbundled Loop - Distribution.

                9.3.5.2  Unbundled Loop - Concentrators/Multiplexers.

                9.3.5.3  Unbundled Loop - Feeder.

                9.3.5.4  Loop/Network Combination. This Combination is described
                         on SCHEDULE 9.3.5.  
                            --------------

                9.3.5.5  Switching Combination #2. This Combination is described
                         on SCHEDULE 9.3.5.
                            --------------

                                      30
<PAGE>
 
                9,3.5.6  Switching Combination #3. This Combination is 
                         described on SCHEDULE 9.3.5.
                                      --------------
                9.3.5.7  Switched Data Services. This Combination is described 
                         on SCHEDULE 9.3.5.
                            --------------

                9.3.5.8  Unbundled Element Platform without Operator Services
                         and Directory Assistance. This Combination is described
                         on SCHEDULE 9.3.5. 
                            --------------

          9.3.6 Any request by Focal for Ameritech to provide any Combination
other than as set forth in SECTION 9.3.4, to combine the unbundled Network
                           -------------
Elements of Ameritech with Focal, or to perform any other function under this
SECTION 9.3 shall be made by Focal in accordance with SECTION 9.6
- -----------                                           ----------- 

     9.4  NONDISCRIMINATORY ACCESS TO AND PROVISION OF NETWORK ELEMENTS

          9.4.1 Subject to SECTION 9.4.4, the quality of an unbundled Network
                           ---------------                                  
Element as well as the quality of the access to such unbundled Network Element
that Ameritech provides to Focal shall be the same for all Telecommunications
Carriers requesting access to such Network Element.

          9.4.2 Subject to SECTION 9.4.4, the quality of a Network Element, as
                           -------------
well as the quality of the access to such Network Element, that Ameritech
provides to Focal hereunder shall be at least equal in quality to that which
Ameritech provides to itself, its subsidiaries, Affiliates and any other person,
unless Ameritech proves to the Commission that it is not technically feasible to
provide the Network Element requested by Focal or access to such Network Element
at a level of quality that is equal to that which Ameritech provides to itself.

          9.4.3 Ameritech shall provide Focal access to Network Elements and
Operations Support Systems functions, including the time within which Ameritech
provisions such access to Network Elements, on terms and conditions no less
favorable than the terms and conditions under which Ameritech provides such
elements to itself, its subsidiaries, Affiliates and any other person, except as
may be provided by the Commission pursuant to SECTION 9.1.2.
                                              -------------

          9.4.4 Upon the request of Focal, Ameritech shall provide to Focal a
Network Element and access to such Network Element that is different in quality
to that required under SECTIONS 9.4.2 and 9.4.3, unless Ameritech proves to the
                       --------------     -----                                
Commission that it is not technically feasible to provide the requested Network
Element or access to such Network Element at the requested level of quality. Any
request by Focal for Ameritech to provide any Network Element or access thereto
that is different in quality shall be made by Focal in accordance with SECTION
                                                                       -------
9.6.
- ---

                                      31
<PAGE>
 
     9.5  PROVISIONING OF NETWORK ELEMENTS.

          9.5.1 Ameritech shall provide Focal unbundled Network Elements as set
forth on SCHEDULE 9.5.
         ------------

          9.5.2 Ameritech shall provide Focal access to the functionalities for
Ameritech's pre-ordering, ordering, provisioning, maintenance and repair and
billing functions of the Operations Support Systems functions that relate to the
Network Elements that Focal purchases hereunder. Access to such functionalities
for the Operations Support Systems functions shall be as provided in SCHEDULE
                                                                     --------
9.2.6 and the Implementation Plan.
- -----

          9.5.3 Prior to submitting an order for a Network Element which 
                   -------------                                              
replaces, in whole or in part, a service offered by Ameritech or any other
telecommunications provider for which Ameritech changes a primary local
exchange carrier, Focal shall comply with the requirements of SECTION 10.11.1.
                                                              ---------------

     9.6  AVAILABILITY OF ADDITIONAL OR DIFFERENT QUALITY NETWORK ELEMENTS.

Any request by Focal for access to a Network Element or a Combination or a
standard of quality thereof that is not otherwise provided by the terms of this
Agreement at the time of such request shall be made pursuant to a Bona Fide
Request and shall be subject to the payment by Focal of all applicable costs in
accordance with Section 252(d)(1) of the Act to process, develop, install and
provide such Network Element, Combination or access.

     9.7  PRICING OF UNBUNDLED NETWORK ELEMENTS.


          9.7.1 Ameritech shall charge Focal the non-recurring and monthly
recurring rates for unbundled Network Elements (including the monthly recurring
rates for these specific Network Elements, service coordination fee, and Cross-
Connect charges) as specified at Item V of the Pricing Schedule. If Focal
requests or approves an Ameritech technician to perform services in excess of or
not otherwise contemplated by the Line Connection Service, Ameritech may charge
Focal for any additional and reasonable labor charges to perform such services.

          9.7.2 In addition to any other applicable charges under this ARTICLE 
                                                                       -------
IX, if Focal purchases unbundled Local Switching elements, Focal shall pay
- --
Ameritech:

          (a)  for interstate minutes of use traversing such unbundled Local
               Switching elements, the carrier common line charge described in
               47 C.F.R. (S) 69.105 and a charge equal to seventy-five percent
               (75%) of the interconnection charge describe in 47 C.F.R. (S)
               69.124, only until the earliest of the following, and not
               thereafter:

               (1)  June 30, 1997;

                                      32
<PAGE>
 
                (2)  The later of the effective date of a final FCC decision in
                     CC Docket No. 94-45, Federal-State Joint Board on
                                          ----------------------------
                     Universal Service, or the effective date of a final FCC
                     -------------------                                    
                     decision in a proceeding, to consider reform of interstate
                     access charges; or

                (3)  The date on which Ameritech is authorized to offer in-
                     region interLATA service in Michigan pursuant to Section
                     271 of the Act; and

           (b)  for intrastate toll minutes of use traversing such unbundled
                Local Switching elements, intrastate access charges comparable
                to those listed in SECTION 9.7.2(A) and any explicit intrastate
                                   ----------------
                universal service mechanism based on access charges, only until
                the earliest of the following, and not thereafter:

                (1) June 30, 1997;
                                                                              
                                                                              
                (2) The effective date of the Commission's decision that      
                    Ameritech may not assess such charges; or                 
                                                                              
                (3) The date on which Ameritech is authorized to offer in-    
                    region interLATA service in Michigan pursuant to Section  
                    271 of the Act.                                           

          9.7.3 If Focal orders a Combination identified in SECTION 9.3.4 and
                                                            -------------
the provision of any such Combination requires Ameritech to modify any of its
existing systems, service development processes or its network (beyond that
required for Ameritech to provision its own retail services) to provide access
to such Combination, Focal shall be required to compensate Ameritech for any
costs incurred to Provide access to such Combination.

      9.8 BILLING. Ameritech shall bill Focal for access to unbundled Network
Elements pursuant to the requirements of ARTICLE XXVII to this Agreement.
                                         -------------       

      9.9 MAINTENANCE OF UNBUNDLED NETWORK ELEMENTS.

          9.9.1 Ameritech shall provide maintenance of Loops and Combinations
that include Loops as set forth in SCHEDULE 10.13.
                                   ---------------

          9.9.2 If (i) Focal reports to Ameritech a suspected failure of a
Network Element, (ii) Focal requests a dispatch, (iii) Ameritech dispatches a
technician, and (iv) such trouble was not caused by Ameritech's facilities or
equipment, then Focal shall pay Ameritech a trip charge and time charges as set
forth at Item V of the Pricing Schedule.


                                      33
<PAGE>
 
      9.10 STANDARDS OF PERFORMANCE.

           9.10.1 Ameritech shall provide to Focal access to unbundled Network
Elements (i) in accordance with SECTION 9.4 as determined by this SECTION 9.10
                                ------------                      ------------
(including any Combinations, service levels and intervals that may be requested
by Focal and agreed upon by the Parties pursuant to a Bona Fide Request) and
(ii) as required by the Commission (collectively, the "AMERITECH NETWORK ELEMENT
PERFORMANCE BENCHMARKS").

           9.10.2 To determine Ameritech's compliance with the Ameritech
Network Element Performance Benchmarks, Ameritech shall maintain records of
specific criteria listed in SCHEDULE 9.10 which criteria are the criteria that
                            -------------                                    
Ameritech currently measures to evaluate its provision of unbundled Network
Elements and (ii) such additional criteria the Parties agree upon regarding
Ameritech's compliance with different performance levels and intervals of such
Network Elements (and Combinations thereof) requested by Focal and provided by
Ameritech pursuant to Section 9.6 and a Bona Fide Request (each, a "NETWORK  
                      -----------                                           
ELEMENT PERFORMANCE ACTIVITY") relating to the access to unbundled Network
Elements Ameritech provides to itself, its subsidiaries and Affiliates (the
"AMERITECH NE RECORDS") and parallel records of the access to unbundled Network
Elements Ameritech provides to (i) Focal (the "FOCAL NE RECORDS") and (ii)
other LECs in the aggregate (the "OTHER LEC NE RECORDS"). In addition, the
Parties may supplement the Network Element Performance Activities as
provides in SECTION 18.6. The criteria will be revised in accordance with
            ------------                                                 
the procedures set forth in the Implementation Plan if Ameritech no longer 
measures a criterion in assessing, its performance in providing Network 
Elements or beings measuring additional criteria.

          9.10.3 Ameritech shall provide to Focal for each Reporting Period, by
the twenty-second (22nd) day of the following month, in a self-reporting
format the Ameritech NE Records, the Focal NE Records and the Other LEC NE
Records so that the Parties can determine Ameritech's compliance with the
Ameritech Network Element Performance Benchmarks. If (i) Ameritech fails to
comply with an Ameritech Network Element Performance Benchmark with respect to a
Network Element Performance Activity for a Reporting Period, (ii) the sample
size of the Network Element Performance Activity measured for such Reporting
Period is statistically valid and (iii) the amount by which the applicable
Ameritech Network Element Performance Activity deviates from the corresponding
Network Element Performance Benchmark is statistically significant, then
Ameritech shall have committed a "SPECIFIED PERFORMANCE BREACH". Notwithstanding
anything to the contrary in this SECTION 9.10.3, the Parties acknowledge that
                                 --------------
(x) Ameritech shall not be required to provide to Focal those Other LEC NE
Records that correspond to and measure a level of quality and performance levels
and intervals of unbundled Network Elements that are requested by an Other LEC
pursuant to 47 C.F.R. (S)51.311(c) and SECTION 9.6 and which are superior to
                                       -----------
that which Ameritech provides to Focal hereunder, (y) the Other LEC NE Records
shall be provided to Focal on an aggregate basis and (z) such Other LEC NE
Records shall be provided to Focal in a manner that preserves the
confidentiality of each other LEC and any of such LEC's proprietary information
(including CPNI).

          9.10.4 In no event shall Ameritech be deemed to have committed a
Specified Performance Breach if Ameritech's failure to meet or exceed a Network
Element Performance

                                      34
<PAGE>
 
Activity is caused by a Delaying Event. If a Delaying Event (i) prevents
Ameritech from performing a certain function or action that affects a Network
Element Performance Activity, then such occurrence shall be excluded from the
calculation of such Network Element Performance Activity and the determination
of Ameritech's compliance with the applicable Ameritech Network Element
Performance Benchmark or (ii) only suspends Ameritech's ability to timely
perform such Network Element Performance Activity, then the applicable time
frame in which Ameritech's compliance with the Ameritech Network Element
Performance Benchmark is measured shall be extended on a like-time basis equal
to the duration of such Delaying Event.

          9.10.5    Upon the occurrence of a Specified Performance Breach by
Ameritech, Focal may forego the dispute escalation procedures set forth in
SECTION 28.3 and (i) bring an action against Ameritech in an appropriate Federal
- -------------                                                                   
district court, (ii) file a complaint against Ameritech with the FCC pursuant
to Sections 207 or 208 of the Act, (iii) seek a declaratory ruling from the
FCC, (iv) file a complaint in accordance with the rules, guidelines and
regulations of the Commission or (iv) seek other relief under Applicable Law.

          9.10.6    Focal shall also be entitled to any Credit Allowances
pursuant to the same terms and conditions that the Ameritech offers Credit
Allowances to its Customers, including those described on SCHEDULE 10.9.6.
                                                          ----------------

          9.10.7    The Parties' agreement to the procedures set forth in this
SECTION 9.10 shall not (i) relieve either Party of its obligations to perform
- ------------                                                                   
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the party requirements of this Agreement and of the 
Act have or have not been met.

                                   ARTICLE X
                 RESALE AT WHOLESALE RATES--SECTION 251(C)(4)

     10.1 TELECOMMUNICATIONS SERVICES AVAILABLE FOR RESALE AT WHOLESALE RATES.
Commencing on the date on which the Commission approves this Agreement, at the
request of Focal, Ameritech will make available to Focal for resale at wholesale
rates those Telecommunications Services that Ameritech provides at retail to
subscribers who are not Telecommunications Carriers, as required in Section 
251(c)(4) of the Act. Subject to the terms, conditions and limitations set forth
in this Agreement, Ameritech will make available to Focal for such resale all
Telecommunications Services which it offers to its retail Customers, including
the following categories of Telecommunications Services (the "RESALE SERVICES") 
as listed on SCHEDULE 10.1.
             -------------

          (i)       Local Service - Residence, as described in the applicable
                    tariff,

          (ii)      Local Service - Business, as described in the applicable
                    tariff,

          (iii)     Message Toll Service, as described in the applicable tariff,

                                      35
<PAGE>
 
          (iv)      PBX Trunk, as described in the applicable tariff;

          (v)       ISDN Direct Service, as described in the applicable tariff;

          (vi)      ISDN Prime Services, as described in the applicable tariff;

          (vii)     Ameritech Centrex Service, as described in the applicable
                    tariff;

          (viii)    Dedicated Communications Services, as described in the
                    applicable tariff;

          (ix)      Inbound Services, as described in the applicable tariff; and

          (x)       Customer Owned Pay Telephone Services, as described in the
                    applicable tariff.

The Resale Services shall be made available to Focal at the rates set forth at
Item VI of the Pricing Schedule.

     10.2 OTHER SERVICES. Ameritech may, at its sole discretion, and as agreed
to by Focal, make available to Focal under this Agreement services other than
Telecommunications Services (e.g., voicemail) for resale at rates, terms and
conditions agreed upon by the Parties.

     10.3 LIMITATIONS ON AVAILABILITY OF RESALE SERVICES.

The following limitations shall apply to Resale Services:

          10.3.1    Any Telecommunications Services which Ameritech offers to
existing retail subscribers, but not to new subscribers ("GRANDFATHERED
SERVICES") are listed on SCHEDULE 10.3.1. SCHEDULE 10.3.1 may be revised or
                         ---------------  ---------------   
supplemented from time to time to include those additional services that
Ameritech may, in its discretion and to the extent permitted by Applicable Law,
classify as Grandfathered Services. Ameritech agrees to make Grandfathered
Services available to Focal for resale to any Customer of Ameritech that
subscribes to a Grandfathered Service from Ameritech at the time of its
selection of Focal as its primary local exchange carrier. If a local
Telecommunications Service is subsequently classified as a Grandfathered Service
by Ameritech, Ameritech agrees to continue to sell such Grandfathered Service
(subject to the terms of SECTION 10.3.2) to Focal for resale to Focal's
                         --------------
Customers that subscribe to such Grandfathered Service at the time it is so
classified by Ameritech. Grandfathered Services shall be made available to Focal
at wholesale rates determined in accordance with the Act. To the extent that
Ameritech is unable to provide wholesale systems support and billing within the
first ninety (90) days from the date each Focal Resale Customer is provided such
Grandfathered Service, Ameritech shall retroactively apply such wholesale rate
as a credit to Focal and will bill such service to Focal from its retail billing
systems.

                                      36
<PAGE>
 
          10.3.2    Any Telecommunication Services which Ameritech currently
intends to discontinue offering to any retail subscriber ("SUNSETTED SERVICES")
are set forth on SCHEDULE 10.3.1. SCHEDULE 10.3.1 may be revised or supplemented
                 ---------------  ---------------
from time to time to include those additional Telecommunications Services that
Ameritech may, in its discretion and to the extent permitted by Applicable Law,
classify as Sunsetted Services. Ameritech agrees to make Sunsetted Services
available to Focal for resale to Focal's Customers who are subscribers to the
Sunsetted Service either from Ameritech or Focal at the time so classified
(subject to the provisions of SECTION 10.3.1 if such Sunsetted Service was
                              -------------- 
previously classified as a Grandfathered Service) until the date such service
is discontinued.

          10.3.3    Each Party acknowledges that Resale Services shall be
available to Focal on the same basis as offered by Ameritech to itself or to any
subsidiary, Affiliate, or any other person to which Ameritech directly provides
the Resale Services, including Ameritech's retail Customers and other
resellers of Ameritech's Telecommunications Services (i) on1y in those service
areas in which such Resale Services (or any feature or capability thereof)
are offered by Ameritech to itself or to any subsidiary, Affiliate, or any
other person, including Ameritech's retail Customers and (ii) to the same extent
as Ameritech's retail Telecommunications Services are subject to the
availability of facilities.

     10.4 ADDITIONAL CHARGES FOR RESALE SERVICES. In addition to the rates set
forth at Item VI of the Pricing Schedule, Focal shall pay Ameritech (i) for any 
applicable charges or fees, if any, incident to the establishment or provision 
of the Resale Services requested by Focal, including channel charges, initial 
non-recurring charges and construction charges and (ii) the applicable non
discounted end user common line charge as set forth in F.C.C. No. 2, Section 4.

     10.5 RESTRICTIONS ON RESALE SERVICES.
          
          10.5.1    To the extent provided by Applicable Law, including Section
357(2) of the Michigan Telecommunications Act, Focal may not offer Resale
Services that are made available only to residential Customers or to a limited
class of residential Customers to classes of Customers that are not eligible to
subscribe to such services from Ameritech.

          10.5.2    Ameritech shall not be required to provide to Focal Resale 
Services offered at a special promotional rate if:

          (a)       Such promotions involve rates that will be in effect for no 
                    more than ninety (90) days; and 

          (b)       Such promotional offerings are not used to evade the
                    wholesale rate obligation; for example, by making available
                    a sequential series of ninety (90) day promotional rates.

                                      37
<PAGE>
 
          10.5.3    Nothing in this Agreement shall require Ameritech to provide
to Focal promotional service elements that are not Telecommunications Services
(i.e., customer-premises equipment).
 ---                             

          10.5.4    Unless permitted by the Commission or FCC after the
Effective Date, Focal shall not utilize Resale Services to avoid applicable
access charges.

          10.5.5    As provided in the Act, Focal may not purchase Resale
Services unless such services are resold to a person other than Focal, its
subsidiaries and Affiliates.

          10.5.6    Ameritech may impose additional restrictions on Focal's sale
of Resale Services only as permitted by the Act, Commission and the FCC.

     10.6 NEW RESALE SERVICES: CHANGES IN PROVISION OF RESALE SERVICES.
Ameritech shall, via tariff filings and as provided in the Implementation Plan,
notify Focal of any changes in the terms and conditions under which Ameritech
offers Resale Services, including the introduction of any new features, 
functions, services or promotions. If a tariff filing provides less than 
forty-five (45) days' notice, Ameritech shall provide not less than forty-five
(45) days' advance notice of such introduction. In addition, Ameritech shall
furnish Focal with reasonable quantities of publicly available collateral
information regarding the Resale Services.

     10.7 OPERATIONS SUPPORT SYSTEMS FUNCTIONS. Ameritech shall provide Focal,
upon Focal's request and pursuant to the Implementation Plan, nondiscriminatory
access to Ameritech's Operations Support Systems functions for pre-ordering,
ordering, provisioning, maintenance and repair, and billing.

     10.8 NONDISCRIMINATORY PROVISION OF RESALE SERVICES.

          10.8.1    Resale Services made available by Ameritech for resale
hereunder and Operations Support Systems functions for ordering, provisioning, 
repair, maintenance and billing shall be equal in quantity to that provided by 
Ameritech to itself or to any subsidiary, Affiliate or any other person to which
Ameritech directly provides the Resale Service, including Ameritech's retail 
Customers.

          10.8.2    Ameritech shall provision Resale Services with the same
timeliness that such Resale Services are provisioned to Ameritech's 
subsidiaries, Affiliates, or other persons to whom Ameritech directly provides
the Resale Service, including Ameritech's retail Customers.

     10.9 STANDARDS OF PERFORMANCE.

          10.9.1    Ameritech shall provide Resale Services to Focal (i) in
accordance with SECTION 10.8 as determined by this SECTION 10.9 and (ii) as
                ------------                       ------------
required by the Commission (collectively, the "RESALE PERFORMANCE BENCHMARKS").

                                      38
<PAGE>
 
          10.9.2    To determine Ameritech's compliance with the Resale
Performance Benchmarks, Ameritech shall maintain records of specific criteria
listed in SCHEDULE 10.9.2 (each, a "RESALE PERFORMANCE ACTIVITY") relating to
          ---------------
Resale Services it provides to itself and to its subsidiaries, Affiliates and
Ameritech's retail Customers (the "AMERITECH RESALE RECORDS") and parallel
records of the Resale Services provided to (i) Focal (the "FOCAL RECORDS") and
(ii) on an aggregate basis, resellers of Telecommunications Services other than
Focal (the "OTHER RESELLER RECORDS").

     Ameritech believes, after good faith inquiry, that SCHEDULE 10.9.2 is a
                                                        ---------------
complete and accurate description of all criteria used as of the Effective Date
by Ameritech to measure Resale Services provided to itself and to its
subsidiaries, Affiliates or its Retail Customers. The criteria will be revised 
in accordance with the procedures set forth in the Implementation Plan if 
Ameritech no longer measures a criterion in assessing its performance in
providing such Resale Service to Ameritech's retail Customers or begins
measuring additional criteria.

          10.9.3    Ameritech shall provide to Focal for each Reporting Period, 
by the twenty-second (22nd) day of the following month, in a self-reporting 
format, the Ameritech Resale Records, the Focal Resale Records and the Other 
Reseller Records so that the Parties can determine Ameritech's compliance with 
the Resale Performance Benchmarks. If (i) Ameritech falls to comply with a 
Resale Performance Benchmark with respect to a Resale Performance Activity for 
a Reporting Period, (ii) the sample size of the Resale Performance Activity 
measured for such Reporting Period is statistically valid, and (iii) the amount 
by which the applicable Resale Performance Activity deviates from the 
corresponding Resale Performance Benchmark is statistically significant, then 
Ameritech shall have committed a "SPECIFIED PERFORMANCE BREACH." 
Notwithstanding anything to the contrary in this SECTION 10.9.3, the Parties 
                                                 --------------
acknowledge that the Other Reseller Records shall be provided to Focal (x) on 
an aggregate basis and (y) in a manner that preserves the confidentiality of 
each other reseller and any of such reseller's proprietary information 
(including CPNI).

          10.9.4    In no event shall Ameritech be deemed to have committed a
Specified Performance Breach if Ameritech's failure to meet or exceed a Resale
Performance Activity is caused by a Delaying Event. If a Delaying Event (i)
prevents Ameritech from performing a certain function or action that affects a 
Resale Performance Activity, then such occurrence shall be excluded from the 
calculation of such Resale Performance Activity and the determination of 
Ameritech's compliance with the applicable Resale Performance Benchmark or
(ii) only suspends Ameritech's ability to timely perform such Resale Performance
Activity, then the applicable time frame in which Ameritech's compliance with
the Resale Performance Benchmark is measured shall be extended on a like-time
basis equal to the duration of such Delaying Event.

          10.9.5    Upon the occurrence of a Specified Performance Breach by
Ameritech, Focal may elect one of the following two remedies:

           (a)      Forego the dispute escalation procedures set forth in 
                    Section 28.3 and (i) bring an action against Ameritech in 
                    ------------
                    an appropriate Federal district court, (ii)

                                      39
<PAGE>
 
                    file a complaint against Ameritech with the FCC pursuant to
                    Sections 207 or 208 of the Act, (iii) seek a declaratory
                    ruling from the FCC, (iv) file a complaint in accordance
                    with the rules, guidelines and regulations of the Commission
                    or (v) seek other relief under Applicable Law; or

          (b)       Ameritech shall pay to Focal as liquidated damages any
                    amounts that Focal is entitled to receive under then
                    existing Commission procedures relating to the failure by
                    Ameritech to comply with the Commission performance
                    standards.

          10.9.6    Focal shall also be entitled to any Credit Allowances
pursuant to the same terms and conditions that Ameritech offers Credit
Allowances to its retail Customers, including those described on SCHEDULE 
                                                                 --------    
10.9.6.
- ------

          10.9.7      The Parties' agreement to the procedures set forth in this
SECTION 10.9 shall not (i) relieve either Party of its obligations to perform
- ------------
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the parity requirements of this Agreement and of the
Act have or have not been met.

    10.10 BRANDING
          
          10.10.1     If Operator Call Completion or Directory Assistance
Service is a feature of an offered Resale Service, Ameritech shall rebrand or
unbrand such features of such offered Resale Service as requested by Focal for
Focal's Customers, unless Ameritech places a restriction on such rebranding or
unbranding that is approved by the Commission as reasonable and
nondiscriminatory, such as proving that Ameritech lacks the capability to comply
with such rebranding or unbranding request.

          10.10.2     Ameritech shall make available to Focal, upon Focal's
request, the ability to route:

          (i)       Local Directory Assistance calls dialed by Focal's Customers
                    directly to Focal Directory Assistance Services platform, to
                    the extent such routing is technically feasible; and

          (ii)      Local Operator Services calls (0+, 0-) dialed by Focal
                    Customers directly to the Focal Local Operator Services
                    platform. Such traffic shall be routed over trunk groups
                    between Ameritech End Offices and the Focal Local Operator
                    Services platform, using standard Operator Services dialing
                    protocols of 0+ or 0-, to the extent such routing is
                    technically feasible.

The routing capabilities described above will be implemented according to the
Implementation Plan. To the extent technically feasible, all direct routing
capabilities described in this SECTION 10.10.2 shall permit Focal Customers to
                               ---------------
dial the same telephone numbers for Ameritech Directory

                                      40
<PAGE>
 
Assistance and Local Operator Service that similarly situated Ameritech
Customers dial for reaching equivalent Ameritech services.

          10.10.3   Notwithstanding anything to the contrary in this Agreement, 
the Parties agree that Ameritech shall have no obligation to unbrand or rebrand 
its service technicians or trucks, any customer premises equipment, other 
customer-owned facilities or its outside plant.

          10.10.4   Focal shall not, without Ameritech's prior written consent,
offer any Resale Service to any Customer under any brand name of Ameritech, its
subsidiaries or its Affiliates, nor shall Focal state or imply that there is any
joint business association or any similar arrangement with Ameritech in the
provision of Resale Service to Focal's Customers, except to the extent Focal
deems it necessary to advise its Customers that Ameritech's personnel will
perform work on behalf of Focal under this Agreement.

          10.10.5   In those instances where Focal requires Ameritech personnel
to interface directly with Focal Customers, either orally in person or by
telephone, or in writing, such personnel shall identify themselves as
Ameritech's employees representing Focal.

          10.10.6   Any "NO ACCESS" cards and time and materials invoices
furnished during service calls by Ameritech personnel to Focal Customers shall
be available to Focal for review and shall be provided to Focal Customers in
an unbranded form.

          10.10.7   In no event shall Ameritech personnel acting on behalf of
Focal pursuant to this Agreement provide information to any existing Focal
Customer about Ameritech products or services.

          10.10.8   Focal shall pay Ameritech's costs, if any, pursuant to the
pricing standard in Section 252(d)(1) of the Act and in such amounts or levels
as determined by the Commission for providing any requested branding under this 
SECTION 10.10
- -------------

   10. 11 PRIMARY LOCAL EXCHANGE AND INTEREXCHANGE CARRIER SELECTIONS.

          10.11.1   The Parties shall apply all of the principles set forth in
47 C.F.R. (S) 64.1100 to the process for Customer selection of a primary
local exchange carrier. Ameritech shall not require a disconnect order from an
Focal Customer, or another LEC, in order to process an Focal order for Resale
Service for an Focal Customer. Ameritech shall advise Focal whenever an Focal
Customer has selected another primary local exchange carrier by giving notice
via an electronic interface within twenty-four (24) hours of the change being
provisioned by Ameritech. Until the FCC or the Commission adopts final rules and
procedures regarding a Customer's selection of a primary local exchange carrier,
Focal shall deliver to Ameritech a representation of authorization in the form 
set forth on SCHEDULE 10.11.1 that applies to all orders submitted by Focal 
             ----------------
under this Agreement that require a primary local exchange carrier change. Such 
representation of authorization shall be delivered to Ameritech prior to the 
first order submitted by Focal. Focal shall retain on file all applicable 
Documentation of Authorization (as defined in SCHEDULE 10.11.1),
                                              ----------------
                                      41
<PAGE>
 
including letters of agency, relating to the Customer's selection of Focal as
its primary local exchange carrier, which documentation shall be available for
inspection by Ameritech at its request during normal business hours.

          10.11.2  Carrier Selection Disputes. If any disputes should occur
                   --------------------------
concerning the selection of primary local exchange carriers by the Customers of
a Party, the following dispute escalation procedures shall be followed:

          (a)  If a Customer denies authorizing a change in his or her primary
               local exchange carrier selection to a different LEC
               ("UNAUTHORIZED SWITCHING"), Ameritech shall switch that Customer
               back to Focal in accordance with the terms of Michigan Bell
               Telephone Company Tariff, MPSC #20R, Part 22 (Resale Local
               Exchange Services) (the "RESALE TARIFF"). However, in the case of
               unauthorized changes of Focal Customers to Ameritech, Ameritech
               shall also have the duties of the "Carrier" as enumerated in such
               Resale Tariff, but will pay the $50 compensation, described in
               the Resale Tariff, to Focal.

          (b)  If Ameritech reports or otherwise provides information on
               unauthorized primary local exchange carrier changes to the FCC,
               the Commission or any other governmental entity, Ameritech agrees
               to report on Focal unauthorized primary local exchange carrier
               changes separately from unauthorized PIC changes.

          (c)  The Parties agree that in the event the Resale Tariff is
               withdrawn by Ameritech or materially revised, they will promptly
               meet and negotiate in good faith a revised procedure for
               resolving carrier selection disputes. If the Parties are unable
               to agree upon such revised procedure within thirty (30) days of a
               Party's request to commence the negotiations, the dispute
               resolution procedures set forth in SECTION 28.3 will be
                                                  ------------
               implemented.

          10.11.3  When Ameritech receives an order for Resale Service from
Focal for Focal's Customer, and Ameritech currently provides resale local
exchange telecommunications services to another carrier ("CARRIER OF RECORD")
for the same Customer, Ameritech shall notify such Carrier of Record of such
order coincident with processing the order. It shall then be the responsibility
of the Carrier of Record and Focal to resolve any issues related to that
Customer. Focal agrees to indemnify and hold Ameritech harmless against any and
all Losses that may result from Ameritech acting under this SECTION 10.11.3.
                                                            ---------------

          10.11.4  When notified by Focal or through the Customer Access Record
Exchange system (CARE) that a Customer has changed its presubscribed
interexchange carrier ("PIC") selection only from one IXC to another IXC,
Ameritech shall provision the PIC only change. Ameritech will modify its process
to conform with industry accepted standards and the requirements of the FCC or
the Commission.

                                      42
<PAGE>
 
     10.12  FUNCTIONALITY REQUIRED TO SUPPORT RESALE SERVICE.

            10.12.1  Directory Listing Requirements. Ameritech shall make
                     ------------------------------                    
available to Focal for Focal Customers directory listings in accordance with the
provisions of ARTICLE XV.
              ----------

            10.12.2  LEC - Assigned Telephone Calling Card Numbers. Effective as
                     ---------------------------------------------
of the date of a Customer's subscription to Focal's service, Ameritech will
block the LEC-assigned telephone line calling card number (including area code)
("TLN") from the Line Identification Database ("LIDB").

            10.12.3  Telephone Assistance Program.  Upon conversion to Focal's
                     ----------------------------
Resale Service of an existing Telecommunications Assistance Program Customer, no
exchange of qualification documentation is necessary. Ameritech will continue to
administer the Telecommunications Assistance Program for the Customer on behalf
of Focal. If Focal's Customer is newly qualified for a Telecommunications
Assistance Program, Focal must send Ameritech the necessary qualification
documentation.

            10.12.4  9-1-1 Services. Ameritech shall provide to Focal, for Focal
                     --------------                                           
Customers, 9-1-1 call routing to the appropriate PSAP. Ameritech shall provide
and validate Focal Customer information to the PSAP. Ameritech shall use its
service order process to update and maintain, on the same schedule that it uses
for its retail Customers, the Focal Customer service information in the ALI/DMS
(Automatic Location Identification/Data Management System) used to support 9-1-1
services.

            10.12.5  Special Services. If Ameritech makes a notation on the
                     ----------------                                    
Customer Service Records (CSR) of Customers who qualify for certain services
available to physically challenged individuals (e.g., special discounts)
                                                ----
("SPECIAL SERVICES"), Ameritech shall provide such data to Focal on the CSR made
available to Ameritech for its Customers. For usage by an Focal Customer of a
Telephone Relay Service, Ameritech will provide Focal with all billing
information furnished to Ameritech by the provider of the Telephone Relay
Service.

            10.12.6  Law Enforcement Interfaces. Interfaces with law enforcement
                     --------------------------                               
agencies and other security matters shall be conducted as specified in SCHEDULE
                                                                       --------
10.12.6.
- -------

     10.13  SERVICE FUNCTIONS.

            10.13.1  Point of Contact for Resale Purchase Customer.

            (a)  Primary Point of Contact. Except as otherwise provided in this
                 ------------------------                                    
                 Agreement, Focal shall be the primary point of contact for all
                 Focal Customers.

            (b)  Service Referrals. Ameritech shall refer all questions
                 -----------------                                   
                 regarding any Focal service or product directly to Focal in
                 accordance with the procedures set forth in the Implementation
                 Plan. Ameritech shall use its best efforts to

                                      43
<PAGE>
 
               ensure that all Ameritech representatives who receive inquiries
               regarding Focal services do not in any way disparage or
               discriminate against Focal or its products or services.

          (c)  Customer Contact Employee Training. Ameritech shall provide
               ----------------------------------                       
               training for all its employees who may communicate, either by
               telephone or face-to-face, with Focal Customers to assure that
               the requirements of this Agreement are met. Furthermore, the same
               quality standards that Ameritech requires of its employees when
               contacting an Ameritech Customer (e.g., honesty, respect and
                                                 ---
               courtesy) shall apply when its employees are in contact with
               Focal Customers.

          10.13.2  Operations Support Systems Functions--Provisioning.

          (a)  Electronic Interface for Pre-Ordering, Ordering and Provisioning.
               ----------------------------------------------------------------
               Ameritech will provide an electronic interface for the transfer
               and receipt of data necessary to perform each of the pre-ordering
               ordering, and provisioning functions (e.g., order entry,
                                                     -----
               telephone number selection, and due date selection) associated
               with Resale Services. Initially, the interface for ordering will
               be separate from the interface used for pre-ordering and
               provisioning. By the end of the first quarter of 1997,the
               interface for ordering will migrate to the pre-ordering and
               provisioning interface. The interface will be administered
               through a gateway that will serve as a single point of contact
               for the transmission of such data. The interface will be
               consistent with the Alliance for Telecommunications Industry
               Solutions (ATIS), Telecommunications Industry Forum (TCIF),
               Electronic Data Interchange (EDI) Customer Service Guideline,
               issue 5, and provide the functionality described in SCHEDULE
                                                                   --------
               10.13.2 and Ameritech's Service Order Interface Document, version
               -------
               2.00. The electronic interface to be provided by Ameritech will
               provide system to system communications on a real-time basis
               (response in seconds), with built-in error recovery and built in
               operations, administration and maintenance functionality, at a
               ninety-five percent (95%) network reliability level. However, as
               an industry standard interface is developed by the appropriate
               industry forum, and generally accepted for implementation by the
               industry, Ameritech shall implement such interface.

          (b)  Service Ordering and Provisioning. Service Orders will be placed
               ---------------------------------
               by Focal and provisioned by Ameritech in accordance with the
               procedures described in SECTION 10.7. Any Service Order activity
                                       ------------
               resulting in primary local exchange carrier changes will comply
               with the requirements of 47 C.F.R. (S) 64.1100 and SECTION
                                                                  -------
               10.9.1.
               ------

                                      44
<PAGE>
 
          (c)  Provisioning Support. Ameritech shall provide provisioning
               --------------------
               support to Focal on the same basis Ameritech provides to its
               retail Customers. Provisioning support may be expanded as
               mutually agreed by the Parties.
 
          (d)  Status Reports. After receipt and acceptance of a Service Order,
               --------------
               Ameritech shall provide Focal with service status notices on an
               exception basis.
 
          (e)  Engineering Support. When requested by Focal, Ameritech shall
               -------------------
               provide timely engineering support.

          (f)  Requests for Service Changes. Where Ameritech provides
               ----------------------------                         
               installation, Ameritech's representatives shall inform an Focal
               Customer to contact Focal if such Customer requests a service
               change at the time of installation.

          (g)  Non-Interruption of Service. Except as specifically provided in
               ---------------------------
               this Agreement or pursuant to an order of a court or commission
               of competent jurisdiction, Ameritech may not initiate any
               disconnect, suspension or termination of an Focal Customer's
               Resale Service, unless directed to do so by Focal by transmission
               of a Service Order or Ameritech's receipt of proper authorization
               to change such Customer's primary local exchange carrier to a
               carrier other than Focal.

          10.13.3  Operations Support Systems Functions -- Maintenance.

          (a)  Electronic Interface for Maintenance and Repair. Ameritech will
               -----------------------------------------------              
               provide an electronic interface for the transfer and receipt of
               data necessary to perform the maintenance and repair functions
               (e.g., trouble receipt and trouble status). This interface will
                ----
               be administered through a gateway that will serve as a single
               point of contact for the transmission of such data. The interface
               will be consistent with the Alliance for Telecommunications
               Industry Solutions (ATIS), TI - Telecommunications (TI) -
               Operations, Administration, Maintenance and Provisioning (OAM&P),
               standard TI.227-95 and TI.228-95 and the Ameritech Electronic
               Bonding Interface (EBI) document. However, as an industry
               standard interface is developed by the appropriate industry
               forum, and generally accepted for implementation by the industry,
               Ameritech shall implement such interface.

          (b)  Maintenance. Maintenance will be provided by Ameritech as set
               -----------
               forth in the Implementation Plan and in accordance with the
               requirements set forth in SECTIONS 10.7 and 10.8 and SCHEDULE
                                         -------------     ----     --------
               10.13.
               -----

                                      45
<PAGE>
 
     10.14  RESPONSIBILITIES OF FOCAL.

            10.14.1  Focal shall be responsible for providing to its Customers
and to Ameritech a telephone number or numbers that Focal's Customers can use to
contact Focal in the event of service or repair requests. If Focal's Customers
contact Ameritech with regard to such requests, Ameritech shall inform such
Customers that they should call Focal and will provide Focal's contact numbers
to such Customers. At Focal's request, Ameritech shall provide a "warm" transfer
to Focal of calls it receives from Focal's Customers for service or repair
requests at the rates set forth at Item VI of the Pricing Schedule.

            10.14.2  Focal shall provide Ameritech with accurate and complete
information regarding Focal's Customers in a method reasonably prescribed by
Ameritech to allow Ameritech to keep its Emergency Telephone Number Service
database updated, if Ameritech maintains such a database.

            10.14.3  Prior to the Effective Date,/10/ Focal shall have received
and communicated to Ameritech its Carrier Identification Code and its Access
Carrier Name Abbreviation or Interexchange Access Customer Code.

     10.15  RESPONSIBILITIES OF AMERITECH.

     Ameritech shall provide access to the following services where Ameritech is
the underlying 9-1-1 service provider:

            (i)   Universal Emergency Number service, a telephone exchange
                  communication service which includes lines and equipment
                  necessary for answering, transferring and dispatching public
                  emergency telephone calls originated by persons within the
                  telephone Central Office areas arranged for 9-1-1 calling.

            (ii)  Basic 9-1-1 service (where available) provides for routing all
                  9-1-1 calls originated by Customers having telephone numbers
                  beginning with a given Central Office prefix code or codes to
                  a single PSAP equipped to receive those calls.

            (iii) Enhanced 9-1-1 ("E9-1-1) service, which provides additional
                  features to Basic 9-1-1 service, such as selective routing of
                  9-1-1 calls to a specific PSAP which is selected from the
                  various PSAPs serving Customers within that Central Office
                  area.

________________
/10/  Since the terms of this Agreement are the result of Focal's adoption under
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 10.14.3,
                                                           --------------- 
      shall mean February 10, 1999.

                                      46
<PAGE>
 
Both Focal and its Customers purchasing Resale Service under this Agreement are
not charged for calls to the 9-1-1 number, except as provided in any applicable
tariff or pursuant to Applicable Law.

     10.16  EXCHANGE OF BILLING INFORMATION.

            10.16.1  Ameritech shall provide Focal a specific Daily Usage File
("DUF") for Resale Services provided hereunder ("CUSTOMER USAGE DATA"). Such
Customer Usage Data shall be recorded by Ameritech in accordance with the
Ameritech Electronic Billing System (AEBS) and EMR. The DUT shall include
specific daily usage, including both Local Traffic and IntraLATA Toll Traffic,
in EMR format, for each individual Resale Service and shall include sufficient
detail to enable Focal to bill its Customers for Resale Services provided by
Ameritech. Ameritech will provide to Focal detailed specifications which will
enable Focal to develop an interface for the exchange of Customer Usage Data.
Procedures and processes for implementing the interface will be included in the
Implementation Plan. Except as provided in SECTION 10.16.4, no other detailed
                                           ---------------
billing shall be provided by Ameritech to Focal.

            10.16.2  Interexchange call detail forwarded to Ameritech for
billing, which would otherwise be processed by Ameritech, will be returned to
the IXC and will not be passed through to Focal. This call detail will be
returned to the IXC with a transaction code indicating that the returned call
originated from a resold account. Billing for 900 and 976 calls or other
Information Services Traffic will be passed through when Ameritech records the
message. If Focal does not wish to be responsible for 900 and 976 calls, it must
order blocking for resold lines. When the IXC records the 900 and 976 calls, the
call detail will be returned to the IXC. Upon Focal's request, Ameritech will
recourse charges on 900 and 976 calls to the Information Service provider in
accordance with existing agreements with such providers. If the provider will
not accept recourse, Ameritech will notify Focal, and Focal, at its option and
expense, may pursue any rights which Ameritech may have under such agreements to
contest such charge. If Focal elects not to contest such charges or such
Information Service provider does not accept the recourse, Focal will promptly
pay Ameritech for such charges and the dispute shall be solely between Focal and
the Information Service provider.

            10.16.3  Focal shall be responsible for providing all billing
information to its Customers who purchase Resale Services from Focal.

            10.16.4  Ameritech shall bill Focal for Resale Services provided by
Ameritech to Focal pursuant to the provisions of ARTICLE XXVII. Ameritech shall
                                                 -------------
recognize Focal as the Customer of Record for all Resale Services and will send
all notices, bills and other pertinent information directly to Focal. The bill
will include sufficient data to enable Focal to (i) bill all charges to its
Customers which are not included as Customer Usage Data and (ii) reconcile the
billed charges with the Customer Usage Data.

                                      47
<PAGE>
 
     10.17  USE OF SERVICE.

            10.17.1  Focal, and not Ameritech, shall be responsible to ensure
that its and its Customers' use of the Resale Services comply at all times with
Applicable Law. Ameritech may refuse to furnish or may disconnect Resale
Services of Focal or, as appropriate to Focal's Customer, when:

            (a)   An order is issued by a court, the Commission or any other
                  duly authorized agency, finding that probable cause exists to
                  believe that the use made or to be made of a Resale Service is
                  prohibited by Applicable Law, or

            (b)   Ameritech is notified in writing by a law enforcement agency
                  acting within its jurisdiction that any facility furnished by
                  Ameritech is being used or will be used for the purpose of
                  transmitting or receiving gambling information in interstate
                  or foreign commerce in violation of law.

The provisions described in this SECTION 10.17.1 shall apply only to the
                                 ---------------
specific affected Resale Services.

            10.17.2  Termination of Resale Service shall take place after
reasonable notice is provided to Focal, or as ordered by a court.

            10.17.3  To the extent provided under the Telephone Consumer
Protection Act (47 U.S.C. (S) 227) and regulations thereunder. Resale Service
shall not be used for the purpose of solicitation by recorded message when such
solicitation occurs as a result of unrequested calls initiated by the solicitor
by means of automatic dialing devices. Such devices, with storage capability of
numbers to be called or a random or sequential number generator that produces
numbers to be called and having the capability, working alone or in conjunction
with other equipment, of disseminating a prerecorded message to the number
called and which are calling party or called party controlled, are expressly
prohibited.

            10.17.4  The Resale Services shall not be used in any manner that
interferes with other persons in the use of their Telecommunications Service,
prevents other persons from using their Telecommunications Services, or
otherwise impairs the quality of service to other carriers or Ameritech's
Customers.

            10.17.5  If Focal's use of Resale Services interferes unreasonably
with the Resale Services of other carriers or their customers or Ameritech or
Focal's Customers, Focal shall be required to take Resale Services in sufficient
quantity or of a different class or grade to correct such interference.

                                      48
<PAGE>
 
                                  ARTICLE XI
                    NOTICE OF CHANGES -- SECTION 251(C)(5)
                                        
     If a Party makes (i) a change in its network which will materially affect
the interoperability of its network with the other Party or (ii) changes
Operations Support Systems functions which affect the operations of the other
Party, the Party making the change shall provide reasonable advance written
notice of such change to the other Party within such time period as determined
by the FCC or the Commission and their respective rules and regulations.

                                  ARTICLE XII
                       COLLOCATION -- SECTION 251(C)(6)
                                        
     12.1  PHYSICAL COLLOCATION.

Ameritech shall provide to Focal Physical Collocation on its Premises for
equipment necessary for Interconnection (pursuant to ARTICLE III) or for access
                                                     -----------
to unbundled Network Elements (pursuant to ARTICLE IX), except that Ameritech
                                           ----------
will provide for Virtual Collocation of such equipment if Ameritech demonstrates
to the Commission that Physical Collocation is not practical for technical
reasons or because of space limitations, as provided in Section 2.51 (c)(6) of
the Act. Ameritech shall provide Focal Collocation only for the purpose of
Interconnection or access to Ameritech's Network Elements.

     12.2  VIRTUAL COLLOCATION IN PHYSICAL COLLOCATION SPACE. Where Focal is
Virtually Collocated on the Effective Date in a space that was initially
prepared for Physical Collocation, Focal may elect to (i) retain its Virtual
Collocation on that Premises and expand that Virtual Collocation according to
current procedures and applicable tariffs or (ii) revert to Physical
Collocation, in which case Focal shall coordinate with Ameritech for
rearrangement of its transmission equipment and facilities, for which Ameritech
shall impose no conversion charge. All applicable Physical Collocation recurring
charges shall apply.

     12.3  VIRTUAL COLLOCATION IN VIRTUAL COLLOCATION SPACE. Where Focal is
Virtually Collocated in a space which was initially prepared for Virtual
Collocation, Focal may elect to (i) retain its Virtual Collocation in that space
and expand that Virtual Collocation according to current procedures and the
terms and conditions of this Agreement or (ii) unless it is not practical for
technical reasons or because of space limitations, convert its Virtual
Collocation to Physical Collocation at such Premises, in which case Focal shall
coordinate the construction and rearrangement with Ameritech of its transmission
equipment and facilities for which Focal shall pay Ameritech at the rates set
forth at Item VII of the Pricing Schedule. In addition, all applicable Physical
Collocation recurring charges shall apply.

                                      49
<PAGE>
 
     12.4  NONDISCRIMINATORY COLLOCATION.

           Collocation shall be made available to Focal by Ameritech on a basis
that is at parity to the priorities that Ameritech provides to itself, its
subsidiaries, Affiliates or other persons. The quality of design, performance,
features, functions and other characteristics of Collocation made available to
Focal under this Agreement shall be at parity to that which Ameritech provides
in its network to itself, its subsidiaries, its Affiliates or other persons.

     12.5  ELIGIBLE EQUIPMENT.

Focal may Collocate equipment necessary for Interconnection, or access to
Ameritech's  Network Elements including the following types of equipment:

           (a)  OLTM equipment;

           (b)  multiplexers;

           (c)  Digital Cross-Connect Panels;

           (d)  Optical Cross-Connect Panels;

           (e)  Digital Loop Carrier (utilizing transmission capabilities only);

           (f)  Data voice equipment, and

           (g)  any other transmission equipment collocated as of August 1, 1996
                necessary to terminate basic transmission facilities pursuant to
                47 C.F.R. (S)(S) 64.1401 and 64.1402.

Focal may Collocate equipment necessary for Interconnection or access to
unbundled Network Elements, which shall include equipment used for signal
regeneration (or "hubbing"). Additionally, Focal shall be permitted to collocate
for any purpose, or in any manner or method authorized by the Act, the
Commission or the FCC.

     12.6  TRANSMISSION FACILITY OPTIONS. For both Physical Collocation and 
Virtual Collocation, Focal may either purchase unbundled transmission facilities
(and any necessary Cross-Connection) from Ameritech or provide its own or third-
party leased transmission facilities and terminate those transmission facilities
in its equipment located in its Collocation space at Ameritech's Premises.

     12.7  INTERCONNECTION WITH OTHER COLLOCATED CARRIERS.

Upon written request to Ameritech, Focal shall be permitted to Interconnect its
network with that of another collocating Telecommunications Carrier at
Ameritech's Premises by connecting its

                                      50
<PAGE>
 
collocated equipment to the collocated equipment of the other Telecommunications
Carrier via a Cross-Connection or other connecting transmission facilities so
long as (i) Focal's and the other collocating Telecommunications Carrier's
collocated equipment are both used for Interconnection with Ameritech or for
access to Ameritech's Network Elements, (ii) Focal provides the connection
between the equipment in the collocated spaces via a Cross-Connection or other
connecting transmission facility that, at a minimum, complies in all respects
with Ameritech's technical and engineering requirements and (iii) the
connecting transmission facilities of Focal and the other collocating
Telecommunications Carrier are contained wholly within space provided solely for
Physical Collocation within Ameritech's Premises. If Focal Interconnects its
network with another collocating Telecommunications Carrier pursuant to this
SECTION 12.7, Focal shall, in addition to its indemnity obligations set forth in
- ------------
ARTICLE XXV, indemnify Ameritech for any Loss arising from Focal's installation,
- -----------
use, maintenance or removal of such connection with the other collocated
Telecommunications Carrier, to the extent caused by the actions or inactions of
Focal.

     12.8  INTERCONNECTION POINTS AND CABLES.

Ameritech shall:

           12.8.1  provide Focal an Interconnection point or points physically
accessible by both Ameritech and Focal, at which the fiber optic cable carrying
Focal's circuits can enter Ameritech's Premises; provided that Ameritech shall
                                                 --------                    
designate Interconnection Points as close as reasonably possible to Ameritech's
Premises;

           12.8.2  provide at least two (2) such Interconnection points at
Ameritech's Premises at which there are at least two (2) entry points for
Focal's cable facilities, and at which space is available for new facilities in
at least two (2) of those entry points;

           12.8.3  permit Focal Interconnection of copper or coaxial cable if
such Interconnection is first approved by the Commission; and

           12.8.4  permit Focal Physical Collocation of microwave transmission
facilities, except where such Collocation is not practical for technical reasons
or because of space limitations, in which case Ameritech shall provide Virtual
Collocation of such facilities as required where technically feasible.

     12.9  ALLOCATION OF COLLOCATION SPACE.

           12.9.1  Focal may reserve Collocation space for its future use in
Ameritech's Premises in accordance with the provisions of SCHEDULE 12.9.1.
                                                          ---------------
Ameritech shall notify Focal in writing if another Telecommunications Carrier
requests Collocation space that is reserved by Focal. Focal shall within five
(5) Business Days of receipt of such notice provide Ameritech either (i) written
notice that Focal relinquishes such space or (ii) enforce its reservation of
space in accordance with the provisions of SCHEDULE 12.9.1. Failure of Focal to
                                           ---------------
respond to Ameritech within the foregoing five (5) Business Day period shall be
deemed an election by Focal to relinquish such space.

                                      51
<PAGE>
 
            12.9.2  Ameritech shall not be required to lease or construct
additional space in a Premises to provide Focal Physical Collocation when
existing space in such Premises has been exhausted.

            12.9.3  Focal will provide Ameritech with a two (2)-year rolling
forecast of its requirements for Collocation that will be reviewed jointly on a
yearly basis by the Parties, in accordance with the planning processes described
in SCHEDULE 12.9.3. Ameritech will attempt to deliver Collocation pursuant to
   ---------------                                                         
Focal's forecasts to the extent that Collocation space is then available.

     12.10  SECURITY ARRANGEMENTS. Focal shall adopt, at the request of
Ameritech and at Focal's sole cost and expense, reasonable security arrangements
as designated by Ameritech to separate Focal's Collocation space from
Ameritech's facilities, including the construction of a collocation cage.

     12.11  SUBCONTRACTOR AND VENDOR APPROVAL. Ameritech shall permit Focal to
subcontract the construction and build-out of Physical Collocation arrangements
with contractors approved by Ameritech. Approval of such subcontractors by
Ameritech shall be based on the same criteria it uses in approving contractors
for its own purposes. In addition, Ameritech shall allow Focal to have an
Ameritech-approved vendor install updates to collocated equipment, including
software updates.

     12.12  DELIVERY OF COLLOCATED SPACE.

            12.12.1  Ameritech shall provide Focal with a single point of
contact for all inquiries regarding Collocation. Focal shall request space for
Collocation by delivering a written request to Ameritech. Each request for
Collocation shall include (i) the Premises in which Collocation is requested,
(ii) the amount of space requested, (iii) the interoffice transmission
facilities Focal will require for such space, (iv) the equipment to be housed in
such space, (v) Focal's anticipated power requirements for the space, (vi) 
any extraordinary additions or modifications (i.e., security devices, node
                                              ----
enclosures, HVAC, etc.) to the space or to the Premises to accommodate Focal's
collocated equipment, (vii) the specific level of diversity for fiber and power
cabling to and from the Collocated space and (viii) the date on which Focal
intends to initiate service from such space. Ameritech shall notify Focal in
writing within ten (10) Business Days of receiving Focal's request for
Collocation as to whether the requested space is available. If space is not
available for Physical Collocation, Ameritech shall specify in its notice to
Focal when space for Physical Collocation will be made available to Focal and
shall offer to Focal Virtual Collocation Space in accordance with SECTION
                                                                  -------  
12.12.3. If intraoffice facilities will not be available for Collocation of
- -------
initial service within three (3) months of receipt of Focal's payment of the
Initial COBO fee for Physical Collocation, or twelve (12) weeks after receipt of
Focal's request for Virtual Collocation pursuant to SECTION 12.12.1, then
                                                    ---------------
Ameritech shall provide written notification, within ten (10) Business Days
after the initial walkthrough, as to when the intraoffice facilities will be
made available.

                                      52
<PAGE>
 
          12.12.2  Physical Collocation.

          (a)  If space for Physical Collocation is immediately available at the
               time of Focal's request, Ameritech shall include in its notice to
               Focal (i) the space to be provided and (ii) whether Ameritech can
               deliver the space to Focal by the date set forth in SECTION
                                                                   -------
               12.12.2 (C).
               -----------

          (b)  If Focal's requested Physical Collocation space is available,
               Ameritech and Focal shall have an initial walkthrough of such
               space within ten (10) Business Days after Ameritech's receipt of
               Focal's Initial COBO Payment. Ameritech shall, within ten (10)
               Business Days after such initial walkthrough, provide
               documentation submitted to and received from contractors for any
               work being done on behalf of Focal that will be billed as
               extraordinary expenses and provide for a parallel installation
               sequence.

          (c)  Ameritech shall deliver to Focal the requested space on or before
               the later of (i) one hundred twenty (120) days from Ameritech's
               receipt of Focal's request for Collocation, (ii) ninety (90) 
               days from the receipt of Focal's Initial COBO Payment (as
               provided on SCHEDULE 12.12) and (iii) such other reasonable date
                           --------------                   
               that the Parties may agree upon if it is not feasible for
               Ameritech to deliver to Focal such space within the foregoing
               intervals (such date of delivery referred to as the "DELIVERY 
               DATE").

          (d)  Physical Collocation space ordered by Focal will be made
               available to Focal by Ameritech as more fully described in
               SECTION 1 OF SCHEDULE 12.12.
               ---------    --------------

          (e)  If Ameritech does not provide Focal with its Collocated space by
               the Delivery Date and such delay is caused directly by
               Ameritech's actions or its failure to act (and not by an Focal
               Delaying Event), Focal shall receive a credit of 1/120th of its
               COBO payment for each day after the applicable Delivery Date that
               such Collocated space is not made available.

          (f)  Ameritech may begin billing Focal for recurring charges for the
               Collocated space on the date such space is made available to
               Focal for occupancy (the "OCCUPANCY DATE"). Focal shall vacate
               the Collocated space if either (i) Focal fails to install within
               ninety (90) days of the Occupancy Date the equipment necessary
               to Interconnection and/or access to unbundled Network Elements
               to be housed in such space or (ii) Focal fails to Interconnect to
               the Ameritech network within one hundred eighty (180) days of the
               Occupancy Date or such other negotiated time as may be mutually
               agreed upon by the Parties. If Focal is required to vacate the
               space pursuant to this SECTION 12.12.2(F), Focal shall vacate
                                      ------------------  
               such space within ninety (90) Business Days of the earliest to
               occur of the foregoing events. If, after vacating a space, Focal
               still requires Collocation in that Premises, Focal shall

                                      53
<PAGE>
 
               be required to submit a new request for Collocation pursuant to
               the provisions of SECTION 12.12.1.
                                 ---------------

          (g)  Physical Collocation will be subject to the additional rules and
               regulations set forth in SECTION 2.0 OF SCHEDULE 12.12, and Focal
                                        -----------    --------------   
               shall pay all costs to provide such Collocation.

          (h)  Ameritech shall provide positive confirmation to Focal when
               construction of Focal Collocated space is fifty percent (50%)
               completed. This confirmation shall also include confirmation of
               the scheduled completion date and Delivery Date. The
               Implementation Plan will include a process for determining when
               construction is fifty percent (50%) complete.

          (i)  At Focal's request Ameritech shall provide, within three (3)
               months after receiving Focal's Initial COBO Payment, equipment
               node enclosures at a height of eight (8) feet, without ceiling.
               Where Ameritech cannot feasibly provide Focal with equipment node
               enclosures within such three (3) month period, Ameritech shall
               notify Focal of this fact within ten (10) Business Days from the
               initial walkthrough. The Parties shall then negotiate a
               reasonable time frame.

          (j)  After completion of construction, Focal and Ameritech will
               complete an acceptance walkthrough of all Collocated space
               requested from Ameritech. Exceptions that are noted during this
               acceptance walkthrough shall be corrected by Ameritech within
               thirty (30) days after the walkthrough. Ameritech shall conduct a
               root cause analysis of all exceptions identified. The correction
               of these exceptions from Focal's original request for Collocation
               shall be at Ameritech's expense, subject to any change orders
               requested by Focal.

          12.12.3  Virtual Collocation.

          (a)  If Focal requests Virtual Collocation, or if requested Physical
               Collocation space is not available at a Premises and Focal elects
               Virtual Collocation, and such Virtual Collocation is available at
               the time of Focal's request, Ameritech shall include in its
               notice to Focal described in Section 12.12.1(i) the space to be
                                                    ------- 
               provided and (ii) whether Ameritech can deliver the space to
               Focal by the date set forth in SECTION 12.12.3(C).
                                              ------------------

          (b)  Ameritech and Focal will have an initial walkthrough of the
               Collocated space to be provided to Focal for Virtual Collocation
               on the earlier of (i) ten (10) Business Days of Ameritech's
               verification of the Virtual Collocation space to be provided to
               Focal and (ii) ten (10) Business Days after Ameritech's receipt
               of Focal's request for Virtual Collocation. Ameritech shall
               within ten

                                      54
<PAGE>
 
               (10) Business Days after such walkthrough provide Focal with
               (i) documentation submitted to and received from contractors for
               any work being done on behalf of Focal that will be billed as
               extraordinary expenses and (ii) a parallel installation sequence.

          (c)  Ameritech shall deliver to Focal the requested space on or before
               the later of (i) twelve (12) weeks from Ameritech's receipt of
               Focal's request for Virtual Collocation and (ii) such other
               reasonable date that the Parties may agree upon if it is not
               feasible for Ameritech to deliver to Focal such space within
               twelve (12) weeks (such date of delivery referred to as the
               "DELIVERY DATE") and Ameritech notified Focal of this fact within
               ten (10) Business Days from the initial walkthrough.

          (d)  Virtual Collocation space ordered by Focal will be made available
               to Focal by Ameritech, as more fully described in SECTION 3 of
                                                                 ---------   
               SCHEDULE 12.12.
               --------------
                
          (e)  Ameritech shall provide positive confirmation to Focal when
               construction of Focal-collocated space is fifty percent (50%)
               completed. This confirmation shall also include confirmation of
               the scheduled completion date and the Delivery Date. The
               Implementation Plan will include a process for determining when
               construction is fifty percent (50%) complete.

          (f)  After completion of construction, Focal and Ameritech will
               complete an acceptance walkthrough of all collocated space
               requested from Ameritech. Exceptions that are noted during this
               acceptance walkthrough shall be corrected by Ameritech within
               thirty (30) days after the walkthrough. Ameritech shall conduct a
               root cause analysis of all exceptions identified. The correction
               of these exceptions from the original request for Collocation
               shall be at Ameritech's expense, subject to any change orders
               requested by Focal.

          (g)  Ameritech shall install cross-connects when cross-connecting for
               thru connect purposes as directed by Focal at the rates provided
               at Item VII of the Pricing Schedule.

    12.13 PRICING. The prices charged to Focal for Collocation are set forth at
Item VII of the Pricing Schedule.

    12.14 BILLING. Ameritech shall bill Focal for Collocation pursuant to the
requirements of ARTICLE XXVII to this Agreement.
                -------------

    12.15 COMMON REQUIREMENTS. The requirements set forth on SCHEDULE 12.15
                                                             --------------     
shall be applicable to both Physical and Virtual Collocation.

                                      55
<PAGE>
 
     12.16  ADDITIONAL REQUIREMENTS. The additional requirements set forth on
SCHEDULE 12.16 shall be applicable to Physical Collocation.
- --------------                                            

     12.17  PROTECTION OF SERVICE AND PROPERTY.

            Both Parties shall exercise reasonable care to prevent harm or
damage to the other Party, its employees, agents or Customers, or their
property. Both Parties, their employees, agents, and representatives agree to
take reasonable and prudent steps to ensure the adequate protection of the other
Party's property and services, including:

            12.17.1  Ameritech and Focal shall restrict access to Focal
equipment, support equipment, systems, tools and data, or spaces which contain
or house Focal equipment enclosures, to Focal employees and other authorized 
non-Focal personnel to the extent necessary to perform their specific job
function.

            12.17.2  Focal shall comply at all times with security and safety
procedures and existing, requirements that are defined by Ameritech and
communicated to Focal.

            12.17.3  Ameritech shall allow Focal periodically to inspect or
observe spaces which house or contain Focal equipment or equipment enclosures
and furnish Focal with keys, entry codes, lock combinations, and other materials
or information which may be needed to gain entry into any secured Focal space,
subject to SECTION 12.17.2 and ARTICLE XX and, in the case of Virtual 
           ---------------     ----------
Collocation, payment by Focal of the cost of Ameritech escorts.

            12.17.4  For Physical Collocation, Ameritech shall furnish to Focal
a current written list of Ameritech's employees who Ameritech authorizes to
enter Focal's Physical Collocation space, with samples of the identify 
credential to be carried by such persons.

            12.17.5  Ameritech shall secure external access to the Physical
Collocation space on its Premises in the same or equivalent manner that
Ameritech secures external access to spaces that house Ameritech's equipment.

            12.17.6  For Physical Collocation, Ameritech shall limit the keys
used in its keying equipment or systems for Focal's specific Physical
Collocation space which contain or house Focal equipment or equipment enclosures
to its employees and representatives to emergency access only. Focal shall
further have the right, at its expense, to have locks changed where deemed
necessary for the protection and security of such spaces, provided that Focal
                                                          --------  
shall immediately provide Ameritech with such new keys.

            12.17.7  Ameritech shall use its existing back-up and recovery plan
in accordance with its standard policies for the specific Central Office.

     12.18  STANDARDS OF PERFORMANCE.

                                      56
<PAGE>
 
Ameritech shall provide Collocation to Focal in accordance with the service
levels, procedures and intervals, if any, agreed upon by the Implementation Team
as provided in SECTION 18.6.
               ------------

                                 ARTICLE XIII
                   NUMBER PORTABILITY -- SECTION 251(B)(2).
                                        
     13.1  PROVISION OF LOCAL NUMBER PORTABILITY.

Each Party shall provide to the other Party, to the extent technically feasible,
Local Number Portability in accordance with the requirements of the Act. To the
extent technically feasible, Local Number Portability will be provided by, each
Party with minimum impairment of functionality, quality, reliability and
convenience to subscribers of the other Party's services.

     13.2  INTERIM NUMBER PORTABILITY ("INP").

The Parties agree to provide INP on a reciprocal basis between their networks to
enable their Customers to utilize telephone numbers associated with a Telephone
Exchange Service provided by one Party, in conjunction with a Telephone Exchange
Service provided by the other Party, upon the coordinated or simultaneous
termination of the first Telephone Exchange Service and activation of the second
Telephone Exchange Service. The Parties shall provide reciprocal INP via remote
call forwarding ("RCF"), Direct Inward Dialing ("DID") or through NXX
Migration; provided, in each case that the Customer whose telephone number is
           --------
subject to INP remains within the same serving Wire Center.

     13.3  REMOTE CALL FORWARDING ("RCF").

           13.3.1  If a Telephone Exchange Service Customer of Party A elects to
become a Telephone Exchange Service Customer of Party B, such Customer may elect
to utilize the original telephone number(s) corresponding to the Telephone
Exchange Service(s) it previously received from Party A, in conjunction with the
Telephone Exchange Service(s) it shall now receive from Party B. Provided that
Party B has complied with the requirements of SECTION 10.11.1 and has issued an
                                              ---------------
associated service order to Party A to assign the number to Party B, Party A
shall implement an arrangement whereby all calls to the original telephone
number(s) shall be forwarded on a multiple-path basis to a new telephone
number(s) designated by Party B. Party A shall route the forwarded traffic to
Party B over the appropriate trunks as if the call were a call which had
originated on Party A's network.

           13.3.2  Party B shall become the Customer of Record for the original
Party A's telephone number(s), subject to the RCF or DID arrangements. Party A
shall use its reasonable efforts to provide Party B with a consolidated billing
statement for all collect and billed-to-

                                      57
<PAGE>
 
3rd-number calls associated with those numbers, with sub-account detail by
retained number. Such billing statement shall be delivered in a mutually agreed
format via either paper, electronic file transfer, daily magnetic tape or
monthly magnetic tape. Party A shall provide to Party B the Exchange Message
Record ("EMR") containing detailed records associated with the calls reflected
on the billing statement, as generated by the Ameritech Electronic Billing
System ("AEBS").

           13.3.3  Party A may cancel line-based calling cards and shall, as
directed by Party B, update its LIDB listing for retained numbers subject to
RCF or DID. Ameritech will include billing, number information associated with
numbers used for INP arrangements in its LIDB and will store and administer such
data in the same manner as Ameritech's data for its Customers. Ameritech shall
provide responses to on-line queries to the stored information for the purpose
of calling, card validation, fraud control and billed numbers screening without
charge.

           13.3.4  If a Customer elects to move its Telephone Exchange Service
back to Party A during the continuance of the RCF or DID arrangement, Party B
shall notify Party A of the Customer's termination of service with Party B and
the Customer's instructions regarding its telephone number(s) within two (2)
Business Days of receiving notification from the Customer. Subject to procedures
generally, performed by Party A for potential new Customers (e.g., credit
                                                             ----
checks, receipts of deposit), Party A shall reinstate service to the Customer,
cancel the RCF or DID arrangement, or redirect the RCF, or DID arrangement
pursuant to the Customer's instructions at that time.

           13.3.5  For ported numbers using RCF, Focal shall provide in the 
9-1-1 information Focal provides to Ameritech under this Agreement both the
ported number and Focal's RCF number if Focal has provided such RCF number to
Ameritech. Ameritech shall include such information, if provided by Focal, in
the PSAP database to the extent that the database is capable of storing both
numbers.

     13.4  DIRECT INWARD DIALING. DID service provides trunk-side access to End
Office Switches for direct inward dialing to the other Party's premises
equipment from the telecommunications network to lines associated with the other
Party's switching equipment and must be provided on all trunks in a group
arranged for inward service. In addition, direct facilities are required from
the End Office where a ported number resides to the End Office serving, the
ported Customer. Transport mileage will be calculated as the airline distance
between the End Office where the number is ported and the Interconnection Wire
Center using, the V&H coordinate method. INP-DID must be established with a
minimum configuration of two channels and one (1) unassigned telephone number
per switch, per arrangement for control purposes. Transport facilities arranged
for INP-DID may not be mixed with any other type of trunk group, with no
outgoing calls placed over said facilities. INP-DID will be provided only where
such facilities are available and where the switching equipment of the ordering,
Party is properly equipped. Where INP-DID service is required from more than one
(1) Wire Center or from separate trunk groups within the same Wire Center, such
service provided from each

                                      58
<PAGE>
 
Wire Center or each trunk group within the same Wire Center shall be considered
a separate service.

     13.5 NXX MIGRATION. Where a Party has activated an entire NXX for a single
Customer, or activated a substantial portion of an NXX for a single customer
with the remaining numbers in that NXX either reserved for future use or
otherwise unused, if such Customer chooses to receive service from the other
Party, the first Party shall cooperate with the second Party to have the entire
NXX reassigned (or subsequently reassigned, in the case of subsequent carrier
changes) in the LERG (and associated industry databases, routing tables, etc.)
to an End Office operated by the second Party. Such transfer will be
accomplished with appropriate coordination between the Parties and subject to
standard industry lead-times for movements of NXXs from one switch to another.
In the interim period, prior to the effective date of LERG reassignment, the
existing method of INP will be used.

     13.6  OTHER INTERIM NUMBER PORTABILITY PROVISIONS.

           13.6.1  Each Party shall disclose to the other Party, upon request,
any technical or capacity limitations that would prevent use of a requested
INP implementation in a particular switching office. Both Parties shall
cooperate in the process of porting numbers to minimize Customer out-of-service 
time.

           13.6.2  The Parties shall cooperate in conducting testing to ensure
interconnectivity between systems. Each Party shall inform the other Party of
any system updates that may affect the other Party's network and shall, at
mutually, agreeable times, perform tests to validate the operation of the
network. Additional testing requirements may apply as specified by this 
Agreement.

           13.6.3  Neither Party shall be required to provide Number Portability
for nongeographic services (e.g., 500 and 900 NPAs, 976 NXX number services and
                            ----  
coin telephone numbers) under this Agreement.

           13.6.4  Ameritech and Focal will cooperate to ensure that performance
of trunking and signaling capacity is engineered and managed at levels which are
at parity with that provided by Ameritech to its Customers.

     13.7  COMPENSATION ON TRAFFIC TO INP'ed NUMBERS. The Parties agree that,
under INP, transport and terminating compensation on calls to INP'ed numbers
should be received by each Customer's chosen LEC as if each call to the Customer
had been originally addressed by the caller to a telephone number bearing an 
NPA-NXX directly assigned to the Customer's chosen LEC. In order to accomplish
this objective where INP is employed, the Parties shall utilize the process set
forth in this SECTION 13.7. whereby transport and terminating compensation on 
              ------------                        
calls subject to INP will be passed from the Party (the "PERFORMING PARTY")
which performs the INP to the other Party (the "RECEIVING PARTY") for whose
Customer the INP is provided.

                                      59
<PAGE>
 
           13.7.1  The Parties shall individually and collectively track and
quantify INP traffic between their networks based on the CPN of each call by
identifying CPNs which are INP'ed numbers. The Receiving Party shall charge the
Performing Party for each minute of INP traffic at the INP Traffic Rate
specified in SECTION 13.7.3 in lieu of any other compensation charges for
             --------------  
terminating such traffic.

           13.7.2  By the Interconnection Activation Date in each LATA, the
Parties shall jointly estimate for the prospective year, based on historic data
of all traffic in the LATA, the percentages of such traffic that, if dialed to
telephone numbers bearing, NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("RECIP TRAFFIC"), (ii) intrastate FGD charges ("INTRA TRAFFIC"),
or (iii) interstate FGD charges ("INTER TRAFFIC"). On the date which is six (6)
months after the Interconnection Activation Date, and thereafter on each
succeeding six (6)-month anniversary of such Interconnection Activation Date,
the Parties shall establish new INP traffic percentages to be applied in the
prospective six (6)-month period, based on actual INP traffic percentages from
the preceding six (6)-month period. The Parties may agree to adopt a different
methodology to calculate INP traffic percentages, including identifying
components different from or in addition to those set forth in this SECTION
                                                                    -------
13.7.2.
- ------

           13.7.3  The INP Traffic Rate shall be equal to the sum of:

           (Recip Traffic percentage times the Reciprocal Compensation Rate set
                                     -----
forth at Item II of the Pricing Schedule) plus (Intra Traffic percentage times
                                          ----                           -----  
the Receiving Party's effective intrastate FGD rates) plus (Inter Traffic
                                                      ----
percentage times the Receiving Party's effective interstate FGD rates) .
           -----

           Interstate and intrastate FGD rates shall be calculated utilizing the
effective interstate and intrastate carrier common line (CCL) rates, residual
interconnection charge (RIC) rate elements, local switching (LS) rate elements,
one-half the local transport termination (LTT) rate elements, and one-half the
local transport facility (LTF) rate elements (assuming a five (5)mile LTF).

     13.8  PRICING FOR INTERIM NUMBER PORTABILITY. Each Party shall comply with
the methodoloy (including recordkeeping) established by the FCC or the
Commission with respect to such Party's recovery in a competitively neutral
manner of its costs to provide Interim Number Portability. To the extent
permitted by the FCC or the Commission, such costs shall include a Party's costs
to deliver calls between the other Party's Customers via Number Portability.
Until such time as the Commission establishes such methodology, the Parties
shall bill each other for INP consistent with existing tariffs and Commission
orders.

     13.9  PERMANENT NUMBER PORTABILITY. The Parties shall migrate from RCF or
DID to Permanent Number Portability as soon as practically possible but no later
than the date provided for by the FCC. The Parties shall provide Permanent
Number Portability on a reciprocal basis to

                                      60
<PAGE>
 
each other in accordance with rules and regulations as from time to time
prescribed by the FCC and/or the Commission.

     13.10  OTHER INP METHODS.

Other methods of providing INP, to the extent technically feasible, may be
provided pursuant to a Bona Fide Request.

                                  ARTICLE XIV
             DIALING PARITY -- SECTIONS 251(B)(3) AND 271(E)(2)(B)
                                        
     The Parties shall provide Dialing Parity to each other as required under
Section 25 1 (b)(3) of the Act, except as may be limited by Section 271(e)(2)(B)
of the Act.

                                  ARTICLE XV
                    DIRECTORY LISTINGS -- SECTION 251(B)(3)
                                        
     15.1  DIRECTORY LISTINGS. Ameritech shall cause the Publisher to include
Primary Listings of Focal's Customers ("FOCAL DIRECTORY CUSTOMERS") in its
White Pages Directories under the following terms and conditions:

           15.1.1  Publisher will publish the Primary Listing of Focal Directory
Customers located within the geographic scope of Publisher's directories at no
charge.

           15.1.2  Listing of such Focal Directory Customers will be interfiled
with listings of subscribers of Ameritech and other LECs serving the same
geographic area where such listings are included within a directory.

           15.1.3  Publisher shall provide Focal with a copy of such listings
prior to publication in such form and format as may be mutually agreed to by the
Parties. Both Parties shall use their best efforts to ensure the accurate
listing of such information.

           15.1.4  Ameritech or its Publisher must receive all Primary Listings
of Focal Directory Customers prior to the service order close date for the 
directory in which those listings are to appear. Ameritech or its Publisher will
provide Focal with appropriate service order close dates within thirty (30) days
of this information becoming available.

           15.1.5  Publisher may, at no charge, include Primary Listings of
Focal Directory Customers that Focal provides to Ameritech in other directories
published by Publisher or its Affiliate.

                                      61
<PAGE>
 
           15.1.6   Nothing in this Agreement shall restrict Ameritech's
Publisher's authority as publisher of the directories from altering the
geographic scope, directory life, headings, content or format of the
directories. Publisher will provide information on such alterations at the same
time such information is provided to Ameritech.

           15.1.7   Publisher shall include, in the customer information section
of each White Pages and Yellow Pages Directory, information about Focal
services, including addresses and telephone numbers for Focal Customer service.
The form and content of such customer information shall be provided by Focal to
Ameritech or its Publisher. The charge, if any, for the listing, of such
information will be calculated on the same basis as the charges, if any, paid by
Ameritech for similar listings.

     15.2  LISTING AND LISTING UPDATES. Focal will provide Focal Directory
Customer Listings and Listing Updates to Ameritech or its Publisher on a
nonexclusive basis as follows:

           15.2.1   Focal shall provide its Focal Directory Customer Listings to
Ameritech or its Publisher in a mutually agreeable form and format. Focal
acknowledges that Ameritech or its Publisher may impose a charge for changes to
Focal Directory Customer Listings previously provided by Focal to Ameritech or 
its Publisher.

           15.2.2   Within one (1) Business Day of installation, disconnection
or other change in service (including change of nonlisted or nonpublished
status) affecting the directory assistance database or the directory listing of
an Focal Directory Customer, Focal shall provide Listing Updates to Ameritech or
its Publisher in a form and format acceptable to Publisher Listing Updates on
Focal Directory Customers are to be provided to Ameritech and Listing Updates
for facilities-based Customers of Focal shall be provided to Publisher.

           15.2.3   Focal will cooperate with Publisher to develop a cost-
effective, mutually satisfactory, mechanized or electronic process for the
provision of Focal's Listing Updates to Publisher, which process shall be
available for joint testing within six (6) months of the Effective Date.

           15.2.4   Publisher or Ameritech may sell or license the use of 
Customer Listings, or Listing Updates to third persons without the prior written
consent of Focal; provided, however, that Publisher or Ameritech will not:
                  --------  -------
 
           (a)      disclose nonlisted name and address information to any third
                    person, except as may be necessary to undertake delivery of
                    directories, or to perform other services contemplated 
                    under this Agreement;

           (b)      disclose to any third person the identity of a Customer's or
                    resale Customer's LEC;

           (c)      sell or license such Customer listing information sorted 
                    by carrier, or

                                      62
<PAGE>
 
           (d)      disclose listing information for individual cases where
                    Focal has notified Ameritech to not include listing for
                    third party publication.

           15.2.5   Publisher shall provide initial and secondary delivery of
appropriate White Page Directories for resale Customers of Focal on the same
basis as Publisher delivers White Pages Directories to Ameritech's retail
Customers. Publisher and Focal may enter into a separate directory services
agreement which, among the services provided, would include the delivery of
White Page Directories to facilities-based Customers of Focal.

                                  ARTICLE XVI
                     ACCESS TO POLES, DUCTS, CONDUITS AND
            RIGHTS-OF-WAY -- SECTIONS 251(b)(4) AND 224 OF THE ACT
            AND SECTION 361 OF THE MICHIGAN TELECOMMUNICATIONS ACT
                             (M.C.L. (S)484.2361)
                                        
     16.1  STRUCTURE AVAILABILITY.

           16.1.1   Ameritech shall make available, to the extent it may 
lawfully do so, access to poles, ducts, conduits and Rights-of-way (individually
and collectively, "STRUCTURE") owned or controlled by Ameritech for the
placement of Focal's telecommunications equipment and related facilities
("ATTACHMENTS"). "POLES, DUCTS AND CONDUITS" include entrance facilities and
conduit and riser space; controlled environmental vaults, manholes, telephone
equipment closets, remote terminals, cross-connect cabinets, panels or boxes,
equipment cabinets, pedestals, or terminals, and any other infrastructure used
by Ameritech to place telecommunications distribution facilities. "RIGHTS-OF-
WAY" are easements, licenses or any other right, whether based upon grant,
reservation, contract, law or otherwise, to use property if the property is 
used for distribution facilities. The availability of Ameritech Structure for 
Focal's Attachments is subject to and dependent upon all rights, privileges, 
franchises or authorities granted by governmental entities with jurisdiction, 
existing and future agreements with other persons not inconsistent with SECTION
                                                                        -------
16.19, all interests in property granted by persons or entities public or 
- -----
private, and Applicable Law, and all terms, conditions and limitations of any 
or all of the foregoing, by which Ameritech owns and controls Structure or 
interests therein.

           16.1.2   Ameritech will not make Structure available (1) where, after
taking all reasonable steps to accommodate such request, there is Insufficient
Capacity to accommodate the requested Attachment, and (2) an Attachment cannot
be accommodated based upon nondiscriminatorily applied considerations of safety,
reliability or engineering principles. For purposes of this ARTICLE XVI,
                                                            -----------
"INSUFFICIENT CAPACITY" means the lack of existing available space on or in
Structure and the inability to create the necessary space by taking all
reasonable steps to do so. Before denying a request for access based upon 
Insufficient Capacity, Ameritech will, in good faith, explore potential 
accommodations with Focal. If Ameritech denies a request by Focal for access to
its Structure for Insufficient Capacity, safety, reliability or engineering

                                      63
<PAGE>
 
reasons, Ameritech will provide Focal a detailed, written reason for such denial
as soon as practicable but, in any event, within forty-five (45) days of the
date of such request.

     16.2 FRANCHISES, PERMITS AND CONSENTS. Focal shall be solely
responsible to secure any necessary franchises, permits or consents from
federal, state, county or municipal authorities and from the owners of private
property, to construct and operate its Attachments at the location of the
Ameritech Structure it uses. Focal shall indemnify Ameritech against loss
directly resulting from any actual lack of Focal's lawful authority to occupy
such Rights-of-way and construct its Attachments therein.

     16.3 ACCESS AND MODIFICATIONS. Where necessary to accommodate a request for
access of Focal, and provided Ameritech has not denied access as described in
SECTION 16.1.2, or because Ameritech may not lawfully make the Structure
- --------------
available, Ameritech will, as set forth below, modify its Structure in order to
accommodate the Attachments of Focal. Ameritech may permit Focal to conduct
Field Survey Work and Make Ready Work itself or through its own contractors in
circumstances where Ameritech is unable to complete such work in a reasonable
time frame.

          16.3.1  Before commencing the work necessary to provide such
additional capacity, Ameritech will notify all other parties having Attachments
on or in the Structure of the proposed modification to the Structure. The
modification to accommodate Focal, may at Ameritech's option, include
modifications required to accommodate other attaching parties, including
Ameritech, that desire to modify their Attachments.

          16.3.2  If Focal requests access to an Ameritech Right-of-way
where Ameritech has no existing Structure, Ameritech shall not be required to
construct new poles, conduits or ducts, or to bury cable for Focal but will be
required to make the Right-of-way available to Focal to construct its own poles,
conduits or ducts or to bury its own cable; provided, however, if Ameritech
                                            --------  -------
desires to extend its own Attachments, Ameritech will construct Structure to
accommodate Focal's Attachments.

          16.3.3  The costs of modifying a Structure to accommodate Focal's
request, the requests of another attaching party or the needs of Ameritech shall
be borne by Focal, the other requesting party or Ameritech, respectively, except
that if other parties obtain access to the Structure as a result of the
modification, such parties shall share in the cost of modification
proportionately with the party initiating the modification. An attaching party,
including Ameritech, with a pre-existing Attachment to the Structure to be
modified to accommodate Focal shall be deemed to directly benefit from the
modification if, after receiving notification of the modification, it adds to or
modifies its Attachment. If a party, including Ameritech, uses the modification
to bring its Structure or Attachments into compliance with applicable safety or
other requirements, it shall be considered as sharing in the modification and
shall share the costs of the modification attributable to its upgrade.
Notwithstanding the foregoing, an attaching party or Ameritech with a pre-
existing Attachment to the Structure shall not be required to bear any of the
costs of rearranging or replacing its Attachment if such rearrangement or
replacement is

                                      64 
<PAGE>
 
necessitated solely as a result of an additional Attachment or the modification
of an existing Attachment sought by another attaching party. If an attaching
party, including Ameritech, makes an Attachment to the facility after the
completion of the modification, such party shall share proportionately in the
cost of the modification if such modification rendered the added attachment
possible.

          16.3.4  All modifications to Ameritech's Structure will be owned by
Ameritech. Focal and other parties, including Ameritech, who contributed to the
cost of a modification, may recover their proportionate share of the depreciated
value of such modifications from parties subsequently seeking Attachment to the
modified structure. Any necessary procedures with respect to a Party's recovery
of its proportionate share of the value of any modifications shall be as
prescribed by the Implementation Team.

     16.4 INSTALLATION AND MAINTENANCE RESPONSIBILITY. Focal shall, at its own
expense, install and maintain its Attachments in a safe condition and in
thorough repair so as not to conflict with the use of the Structure by Ameritech
or by other attaching parties. Work performed by Focal on, in or about
Ameritech's Structures shall be performed by properly trained, competent workmen
skilled in the trade. Ameritech will specify the location on the Structure where
Focal's Attachment shall be placed, which location shall be designated in a
nondiscriminatory manner. Focal shall construct each Attachment in conformance
with the permit issued by Ameritech for such Attachment. Other than routine
maintenance and service wire Attachments, Focal shall not modify, supplement or
rearrange any Attachment without first obtaining a permit therefore. Focal shall
provide Ameritech with notice before entering any Structure for construction or
maintenance purposes.

     16.5 INSTALLATION AND MAINTENANCE STANDARDS. Focal's Attachments shall be
installed and maintained in accordance with the rules, requirements and
specifications of the National Electrical Code. National Electrical Safety Code,
Bellcore Construction Practices, the Commission, the Occupational Safety &
Health Act and the valid and lawful rules, requirements and specifications of
any other governing authority having jurisdiction over the subject matter.

     16.6 IMPLEMENTATION TEAM. The Implementation Team to be formed pursuant to
ARTICLE XVIII shall develop cooperative procedures for implementing the terms of
- -------------                                                                   
this ARTICLE XVI and to set out such procedures in the Implementation Plan. The
     -----------
Parties, through the Implementation Team, shall develop mutually agreeable
intervals for completion of process steps in providing Focal access to
Ameritech's Structure and appropriate penalties for failure to timely complete
process steps for which fixed intervals or negotiated intervals have been
assigned. Ameritech will provide Focal with access to information regarding the
provision of access to Ameritech's Structure which will be sufficient for Focal
to verify that Ameritech is providing Focal with access to its Structure that is
comparable to that provided by Ameritech to itself, its subsidiaries, Affiliates
and other persons requesting access to Ameritech's Structure.

     16.7 ACCESS REQUESTS. Any request by Focal for access to Ameritech's 
Structure shall be in writing and submitted to Ameritech's Structure Leasing 
Coordinator. Ameritech may

                                      65
<PAGE>
 
prescribe a reasonable process for orderly administration of such requests.
Focal's Attachment to Ameritech's Structure shall be pursuant to a permit issued
by Ameritech for each request for access.

     16.8  UNUSED SPACE. Excepting maintenance ducts as provided in SECTION 16.9
                                                                    ------------
and ducts required to be reserved for use by municipalities, all useable but
unused space on Structure owned or controlled by Ameritech shall be available
for the Attachments of Focal, Ameritech or other providers of Telecommunications
Services or cable television systems. Focal may not reserve space on Ameritech
Structure for its future needs. Ameritech shall not reserve space on Ameritech
Structure for the future need of Ameritech nor permit any other person to
reserve such space. Notwithstanding the foregoing, Focal may provide Ameritech
with a two (2)-year rolling forecast of its growth requirements for Structure
that will be reviewed jointly on an annual basis.

     16.9  MAINTENANCE DUCTS. One duct and one inner-duct in each conduit
section shall be kept vacant as maintenance ducts. Maintenance ducts shall be
made available to Focal for maintenance purposes if it has a corresponding
Attachment.

     16.10 APPLICABILITY. The provisions of this Agreement shall apply to
all Ameritech Structure now occupied by Focal except for structures covered in
the provisions of Focal Ameritech Easement or Condominium Agreements listed in
SCHEDULE 16.10.
- --------------

     16.11 OTHER ARRANGEMENTS. Focal's use of Ameritech Structure is subject to
any valid, lawful and nondiscriminatory arrangements Ameritech may now or
hereafter have with others pertaining to the Structure.

     16.12 COST OF CERTAIN MODIFICATIONS. If Ameritech is required by a
governmental entity, court or Commission to move, replace or change the
location, alignment or grade of its conduits or poles, each Party shall bear its
own expenses of relocating its own equipment and facilities. However, if such
alteration is required solely due to Ameritech's negligence in originally
installing the structure, Ameritech shall be responsible for Focal's expenses.

     16.13  MAPS AND RECORDS. Ameritech will provide Focal, at Focal's request
and expense, with access to and copies of maps, records and additional
information relating to its Structure; provided that Ameritech may redact any
                                       --------                              
proprietary information (of Ameritech or third parties) contained or reflected
in any such maps, records or additional information before providing such
information to Focal. Upon request, Ameritech will meet with Focal to clarify
matters relating to maps, records or additional information. Ameritech does not
warrant the accuracy or completeness of information on any maps or records.

     16.14  FOCAL ACCESS. Focal shall provide Ameritech with notice before
entering any Ameritech Structure.

     16.15  OCCUPANCY PERMIT. Focal occupancy of Structure shall be pursuant to
a permit issued by Ameritech for each requested Attachment. Any such permit
shall terminate (a) if 
                                 
                                      66 
<PAGE>
 
Focal's franchise, consent or other authorization from federal, state, county or
municipal entities or private property owners is terminated, (b) if Focal has
not placed and put into service its Attachments within one hundred eighty (180)
days from the date Ameritech has notified Focal that such Structure is available
for Focal's Attachments, (c) if Focal ceases to use such Attachment for any
period of one hundred eighty (180) consecutive days, (d) if Focal fails to
comply with a material term or condition of this ARTICLE XVI and does not
                                                 -----------             
correct such noncompliance within sixty (60) days after receipt of notice
thereof from Ameritech or (e) if Ameritech ceases to have the right or authority
to maintain its Structure, or any part thereof, to which Focal has Attachments.
If Ameritech ceases to have the right or authority to maintain its Structure, or
any part thereof, to which Focal has Attachments, Ameritech shall (i) provide
Focal notice within ten (10) Business Days after Ameritech has knowledge of such
fact and (ii) not require Focal to remove its Attachments from such Structure
prior to Ameritech's removal of its own attachments. Ameritech will provide
Focal with at least sixty (60) days' written notice prior to (x) terminating a
permit or service to an Focal Attachment or removal thereof for a breach of the
provisions of this ARTICLE XVI, (y) any increase in the rates for Attachments to
                   -----------                                                  
Ameritech's Structure permitted by the terms of this Agreement, or (z) any
modification to Ameritech's Structure to which Focal has an Attachment, other
than a modification associated with routine maintenance or as a result of an
emergency. If Focal surrenders its permit for any reason (including forfeiture
under the terms of this Agreement), but fails to remove its Attachments from the
Structure within one hundred eighty (180) days after the event requiring Focal
to so surrender such permit, Ameritech shall remove Focal's Attachments at
Focal's expense.

     16.16  INSPECTIONS. Ameritech may make periodic inspections of any part of
the Attachments of Focal located on Ameritech Structures. Where reasonably
practicable to do so, Ameritech shall provide prior written notice to Focal of
such inspections.

     16.17  DAMAGE TO ATTACHMENTS. Both Focal and Ameritech will exercise
precautions to avoid damaging the Attachments of the other or to any Ameritech
Structure to which Focal obtains access hereunder Subject to the limitations in
ARTICLE XXVI, the Party damaging the Attachments of the other shall be 
- ------------                                                          
responsible to the other therefor.

     16.18  CHARGES. Ameritech's charges for Structure provided hereunder shall
be determined in compliance with the regulations to be established by the FCC
pursuant to Section 224 of the Act and in compliance with Section 361 of the
Michigan Telecommunications Act (M.C.L. (S)484 2361) and applicable Commission
rules, regulations and orders thereunder. Prior to the establishment of such
rates, Ameritech's charges for Structure will be those of the lowest existing
contract available to an attaching party in the State of Michigan, including any
Affiliate of Ameritech. A deposit shall be required for map preparation, make-
ready surveys and Make-Ready Work.

     16.19  NONDISCRIMINATION. Except as otherwise permitted by Applicable Law,
access to Ameritech-owned or -controlled Structure shall be provided to Focal on
a basis that is nondiscriminatory to that which Ameritech provides to itself,
its Affiliates, Customers, or any other person.

                                      67
<PAGE>
 
     16.20 INTERCONNECTION.

           16.20.1  Upon request by Focal, Ameritech will permit the
interconnection of ducts or conduits owned by Focal in Ameritech manholes.

           16.20.2  Except where required herein, requests by Focal for
interconnection of Focal's Attachments in or on Ameritech Structure with the
Attachments of other attaching parties in or on Ameritech Structure will be
considered on a case-by-case basis and permitted or denied based on the
applicable standards set forth in this ARTICLE XVI for and reasons of
                                       -----------                   
insufficient Capacity, safety, reliability and engineering. Ameritech will
provide a written response to Focal's request within forty-five (45) days of
Ameritech's receipt of such request.

           16.20.3  Focal shall be responsible for the costs of any Make-Ready
Work required to accommodate any interconnection pursuant to SECTION 16.20.
                                                             -------------

     16.21 COST IMPUTATION. Ameritech will impute costs consistent with the
rules under Section 224(g) of the Act.

     16.22 STRUCTURE LEASING COORDINATOR. Requests for access to Ameritech
Structure shall be made through Ameritech's Structure Leasing Coordinator, who
shall be Focal's single point of contact for all matters relating to Focal's
access to Ameritech's Structure. The Structure Leasing Coordinator shall be
responsible for processing requests for access to Ameritech's Structure,
administration of the process of delivery of access to Ameritech's Structure and
for all other matters relating to access to Ameritech's Structure.

     16.23 STATE REGULATION. The terms and conditions in this ARTICLE XVI shall
                                                              -----------
be modified through negotiation between the Parties to comply with the
regulations of the state in which Ameritech owns or controls Structure to which
Focal seeks access if such state meets the requirements of Section 224(c) of the
Act for regulating rates, terms and conditions for pole attachments and so
certifies to the FCC under Section 224(c) of the Act and the applicable FCC
rules pertaining hereto. The terms and conditions of this ARTICLE XVI shall also
                                                          -----------           
be modified by negotiation between the Parties to comply with any applicable
requirements regarding the application of state law set forth in applicable
Commission rules, regulations and orders and the Michigan Telecommunications 
Act. Until the terms and conditions of this ARTICLE XVI are renegotiated, the
                                            -----------
rules, regulations and orders of such state so certifying shall supersede any
provision herein inconsistent therewith.

     16.24 ABANDONMENTS, SALES OR DISPOSITIONS. Ameritech shall notify Focal of
the proposed abandonment, sale, or other intended disposition of any Structure.
In the event of a sale or other disposition of the conduit system or pole,
Ameritech shall condition the sale or other disposition subject to the rights
granted to Focal.

                                    68    
<PAGE>
 
     16.25 STANDARDS OF PERFORMANCE. Ameritech shall provide Structure to Focal
in accordance with the service levels, procedures and intervals, if any, agreed
upon by the Implementation Team as provided in SECTION 18.6.
                                               ------------

                                 ARTICLE XVII
                             REFERRAL ANNOUNCEMENT

     When a Customer changes its service provider from Ameritech to Focal, or
from Focal to Ameritech, and does not retain its original telephone number, the
Party formerly providing service to such Customer shall provide a referral
announcement ("REFERRAL ANNOUNCEMENT") on the abandoned telephone number which
provides details on the Customer's new number. Referral Announcements shall be
provided reciprocally, free of charge to both the other Party and the Customer,
for the period specified in Michigan Administrative Rule 484,134. However, if
either Party provides Referral Announcements for a period longer than the above
period when its Customers change their telephone numbers, such Party shall
provide the same level of service to Customers of the other Party.


                                 ARTICLE XVIII
                  IMPLEMENTATION TEAM AND IMPLEMENTATION PLAN

     18.1  IMPLEMENTATION TEAM. The Parties understand that the arrangements and
provision of services described in this Agreement shall require technical and
operational coordination between the Parties. The Parties further agree that it
is not feasible for this Agreement to set forth each of the applicable and
necessary procedures, guidelines, specifications and standards that will promote
the Parties' provision of Telecommunications Services to their respective
Customers. Accordingly, the Parties agree to form a team (the "IMPLEMENTATION
TEAM") which shall develop and identify those processes, guidelines,
specifications, standards and additional terms and conditions necessary for the
provision of the services and the specific implementation of each Party's
obligations hereunder. Within five (5) days after the Effective Date,/11/ each
Party shall designate, in writing, not more than four (4) persons to be
permanent members of the Implementation Team; provided that either Party may
                                              --------
include in meetings or activities such technical specialists or other
individuals as may be reasonably required to address a specific task, matter or
subject. Each Party may replace its representatives on the Implementation Team
by delivering written notice thereof to the other Party. The processes described
in this ARTICLE XVIII and agreement reached by the Parties in the Implementation
        -------------                                                           
Plan shall not (i) relieve either Party of its obligations to perform any duties
under this Agreement, the Act or any obligation which must be performed by
January 1, 1997 as

______________________

/11/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 18.1 shall mean
                                                     ------------ 
     February 10, 1999.
     
                                      69
<PAGE>
 
imposed by the FCC or (ii) constitute a waiver of a right of either Party to
claim that the parity requirements of this Agreement and of the Act have or have
not been met.

     18.2  IMPLEMENTATION PLAN. Within ninety (90) days after the Effective 
Date,/12/ the Implementation Team shall reach agreements on items to be
      --
included in an operations manual (the "IMPLEMENTATION PLAN"), which shall
include (i) processes, procedures, and milestone agreements reached by the
Implementation Team, (ii) documentation of the various items described in this
Agreement which are to be included in the Implementation Plan, including the
following matters, and (iii) any other matters agreed upon by the Implementation
Team:

     (1)   A Plan as provided in SECTION 8.1;
                                 ----------- 

     (2)   Access to all necessary OSS functions, including interfaces and
           gateways;

     (3)   Procedures that specify the requisite time period(s) in which
           Ameritech shall give Focal notice and the applicable information and
           ---------
           specifications regarding any changes to interfaces of the OSS
           functions;

     (4)   Escalation procedures for provisioning and maintenance;

     (5)   Single points of contact for provisioning and maintenance;

     (6)   Service ordering and provisioning procedures, including provision of
           the trunks and facilities;

     (7)   Provisioning and maintenance support;

     (8)   Conditioning of Collocation spaces and maintenance of Virtually
           Collocated equipment;

     (9)   Procedures and processes for Directories and Directory Listings;

     (10)  Service referral procedures, including procedures for handling
           misdirected inquiries and calls and procedures for handling out-of-
           service or irate Customers;

     (11)  Training;

     (12)  Billing, including measurements, rating and validation process;

_________________________

/12/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 18.2, shall mean
                                                     ------------
     February 10, 1999.

                                      70
<PAGE>
 
     (13)  Network planning components, including system architecture, planning
           SONET equipment configuration, fiber hand-off, test and acceptance of
           SONET ring, trunking, signaling, and augment process;

     (14)  Joint systems readiness and operational readiness plans; and

     (15)  Guidelines for administering access to Rights-of-way, poles and
           conduits of Ameritech.

     Subject to the terms and conditions of this Agreement (including SECTION
                                                                      ------- 
19.5), the Implementation Plan will ensure that no later than the end of
- ----                                                                   
Contract Month 6 /13/, the operational interfaces will be capable of supporting
all classes and complexities of orders for Network Elements and Resale Services
and all Network Elements and Resale Services are available to order, at all
required volume levels.

     18.3  ACTION OF IMPLEMENTATION TEAM. The Implementation Plan may be amended
from time to time by the Implementation Team as the team deems appropriate.
Unanimous written consent of the permanent members of the Implementation Team
shall be required for any action of the Implementation Team. If the
Implementation Team is unable to act, the existing provisions of the
Implementation Plan shall remain in full force and effect.

     18.4  FURTHER COORDINATION AND PERFORMANCE. Except as otherwise agreed upon
by the Parties, on a mutually agreed-upon day and time once a month during the
Term, the Implementation Team shall discuss the performance of the Parties under
this Agreement. At each such monthly meeting the Parties will discuss: (i) the
administration and maintenance of the Interconnections and trunk groups
provisioned under this Agreement; (ii) the Parties' provisioning of the services
provided under this Agreement; (iii) the Parties' compliance with the
Performance Benchmarks set forth in this Agreement and any areas in which such
performance may be improved; (iv) any problems that were encountered during the
preceding month or anticipated in the upcoming month; (v) the reason underlying
any such problem and the effect, if any, that such problem had, has or may have
on the performance of the Parties; and (vi) the specific steps taken or proposed
to be taken to remedy such problem. In addition to the foregoing, the Parties
through their representatives on the Implementation Team or such other
appropriate representatives will meet to discuss any matters that relate to the
performance of this Agreement, as may be requested from time to time by either
of the Parties.

________________________

/13/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Contract Month 6", for purposes of this SECTION 18.2, shall
                                                       ------------
     expire on July 31, 1999.

                                      71
<PAGE>
 
     18.5  OPERATIONAL REVIEW. Representatives of Focal and Ameritech will meet
on a quarterly basis, beginning with the end of the first quarter of 1997, /14/
                                                                            --
to determine that the service cycle of pre-ordering, ordering, provisioning,
maintenance and billing categories are addressed, including the following:

           (a) Interfaces and processes are operational and the agreed-upon
               numbers of Focal Customers for residential and business Resale
               Services are successfully completed per day;

           (b) Interfaces and processes are operational and the agreed-upon
               numbers of orders for Combinations are successfully completed per
               day;

           (c) When applicable, Interfaces and processes are operational and the
               agreed-upon numbers of orders for unbundled Loops are
               successfully completed per day;

           (d) Review of all agreed-upon performance standards; and

           (e) The accuracy rate for bills for wholesale bill validation
               process.

     18.6  ADDITIONAL DUTIES OF IMPLEMENTATION TEAM. In addition to its
responsibilities under SECTION 18.2, the Implementation Team shall meet in the
                       ------------                                           
fourth Contract Month /15/ after Ameritech first:
                       --

           (1) Provides Focal unbundled Network Elements (or any Combination
               thereof) hereunder, to determine if any additional Network
               Element Performance Activities are required to assess Ameritech's
               performance under SECTION 9.10;
                                 ------------

           (2) Delivers Collocated Space to Focal hereunder, to determine if any
               service levels, procedures or intervals are required to assess
               Ameritech's provision of Collocation under SECTIONS 12.4 and
                                                          ------------- 
               12.12 and the applicable remedies, if any, for Ameritech's
               -----
               failure to perform with any of the foregoing service levels,
               procedures and intervals; and

________________________

/14/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252 (i) of the Act of the Teligent Agreement, the Parties agree
     that the phrase "second quarter of 1999" shall be substituted in lieu of
     the phrase "first quarter of 1997."

/15/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Focal Agreement, the Parties agree that
     the term "Fourth Contract Month", for purposes of this SECTION 18.6, shall
                                                            ------------   
     expire on May 30, 1999.

                                      72
<PAGE>
 
           (3) Provides Focal access to Ameritech Structure hereunder, to
               determine if any service levels, procedures or intervals are
               required to assess Ameritech's provision of Structure under
               SECTIONS 16.6 and 16.19 and the applicable remedies, if any, for
               -------------     -----                   
               Ameritech's failure to perform with any of the foregoing service
               levels, procedures and intervals.

If the Implementation Team is unable to agree upon any of the foregoing service
levels, procedures or intervals or applicable remedies (or whether any such
service levels, procedures, intervals or remedies are necessary), such failure
to agree shall be resolved in accordance with the procedures established in
SECTION 28.3.
- ------------

                                  ARTICLE XIX
                    GENERAL RESPONSIBILITIES OF THE PARTIES

     19.1  COMPLIANCE WITH IMPLEMENTATION SCHEDULE. Each of Ameritech and Focal
shall use its best efforts to comply with the Implementation Schedule.

     19.2  COMPLIANCE WITH APPLICABLE LAW. Each Party shall comply at its own
expense with all applicable federal, state, and local statutes, laws, rules,
regulations, codes, final and nonappealable orders, decisions, injunctions,
judgments, awards and decrees (collectively, "APPLICABLE LAW") that relate to
its obligations under this Agreement.

     19.3  NECESSARY APPROVALS. Each Party shall be responsible for obtaining
and keeping in effect all approvals from, and rights granted by, governmental
authorities, building and property owners, other carriers, and any other persons
that may be required in connection with the performance of its obligations under
this Agreement. Each Party shall reasonably cooperate with the other Party in
obtaining and maintaining any required approvals and rights for which such Party
is responsible.

     19.4  ENVIRONMENTAL HAZARDS. Each Party will be solely responsible at it
own expense for the proper handling, storage, transport, treatment, disposal and
use of all Hazardous Substances by such Party and its contractors and agents.
"HAZARDOUS SUBSTANCES" includes those substances (i) included within the
definition of hazardous substance, hazardous waste, hazardous material, toxic
substance, solid waste or pollutant or contaminant under any Applicable Law and
(ii) listed by any governmental agency as a hazardous substance.

     19.5  FORECASTING REQUIREMENTS.

           19.5 1   The Parties shall exchange technical descriptions and
forecasts of their Interconnection and traffic requirements in sufficient detail
necessary to establish the Interconnections required to assure traffic
completion to and from all Customers in their respective designated service
areas.

                                      73
<PAGE>
 
          19.5.2    Thirty (30) days after the Effective Date/16/ and each month
                                                              --
during the term of this Agreement, each Party shall provide the other Party with
a rolling, six (6) calendar-month, nonbinding forecast of its traffic and volume
requirements for the Interconnection, and Network Elements provided under this
Agreement, in the form and in such detail as agreed by the Parties.
Notwithstanding SECTION 20.1.1, the Parties agree that each forecast provided
                --------------                                               
under this SECTION 19.5.2 shall be deemed "PROPRIETARY INFORMATION" under 
           --------------                                                
ARTICLE XX.
- ----------           

          19.5.3 In addition to, and not in lieu of, the nonbinding forecasts
required by SECTION 19.5.2, a Party that is required pursuant to this 
Agreement--------------to provide a forecast (the "FORECAST PROVIDER") or a
Party that is entitled pursuant to this Agreement to receive a forecast (the
"FORECAST RECIPIENT") with respect to traffic and volume requirements for the
services and Network Elements provided under this Agreement may request that the
other Party enter into to negotiations to establish a forecast (a "BINDING
FORECAST") that commits such Forecast Provider to purchase, and such Forecast
Recipient to provide, a specified volume to be utilized as set forth in such
Binding Forecast. The Forecast Provider and Forecast Recipient shall negotiate
the terms of such Binding Forecast in good faith and shall include in such
Binding Forecast provisions regarding price, quantity, liability for failure to
perform under a Binding Forecast and any other terms desired by such Forecast
Provider and Forecast Recipient. Notwithstanding SECTION 20.1.1, the Parties
agree that each--------------forecast provided under this SECTION 19.5.3 shall
be deemed "PROPRIETARY--------------INFORMATION" under ARTICLE XX.----------

     19.6  CERTAIN NETWORK FACILITIES. Each Party is individually responsible to
provide facilities within its network which are necessary for routing,
transporting, measuring, and billing traffic from the other Party's network and
for delivering such traffic to the other Party's network using industry standard
format and to terminate the traffic it receives in that standard format to the
proper address on its network. Such facility shall be designed based upon the
description and forecasts provided under SECTIONS 19.5.1, 19.5.2 and, if 
                                         ---------------  ------
applicable, 19.5.3. The Parties are each solely responsible for participation in
            ------
and compliance with national network plans, including The National Network
Security Plan and The Emergency Preparedness Plan.

     19.7  TRAFFIC MANAGEMENT AND NETWORK HARM.

           19 7.1   Each Party may use protective network traffic management
controls, such as 7-digit and 10-digit code gaps on traffic toward the other
Party's network, when required to protect the public-switched network from
congestion due to facility failures, switch congestion or failure or focused
overload. Each Party shall immediately notify the other Party of any protective
control action planned or executed.


- ------------------------

/16/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 19.5.2, shall mean
                                                     --------------
     February 10, 1999.

                                      74
<PAGE>
 
          19.7.2    Where the capability exists, originating or terminating
traffic reroutes may be implemented by either Party to temporarily relieve
network congestion due to facility failures or abnormal calling patterns.
Reroutes shall not be used to circumvent normal trunk servicing. Expansive
controls shall be used only when mutually agreed to by the Parties.

          19.7.3    The Parties shall cooperate and share pre-planning
information regarding cross-network call-ins expected to generate large or
focused temporary increases in call volumes, to prevent or mitigate the impact
of these events on the public-switched network.

          19.7.4    Neither Party shall use any product or service provided
under this Agreement or any other service related thereto or used in combination
therewith in any manner that interferes with any person in the use of such
person's Telecommunications Service, prevents any person from using its
Telecommunications Service, impairs the quality of Telecommunications Service to
other carriers or to either Party's Customers, causes electrical hazards to
either Party's personnel, damage to either Party's equipment or malfunction of
either Party's billing equipment.

     19.8   INSURANCE. At all times during the term of this Agreement, each
Party shall keep and maintain in force at such Party's expense all insurance
required by Applicable Law, general liability insurance in the amount of at
least $10,000,000 and worker's compensation insurance. Upon request from the
other Party, each Party shall provide to the other Party evidence of such
insurance (which may be provided through a program of self-insurance).

     19.9   LABOR RELATIONS. Each Party shall be responsible for labor relations
with its own employees. Each Party agrees to notify the other Party as soon as
practicable whenever such Party has knowledge that a labor dispute concerning
its employees is delaying or threatens to delay such Party's timely performance
of its obligations under this Agreement and shall endeavor to minimize
impairment of service to the other Party (by using its management personnel to
perform work or by other means) in the event of a labor dispute to the extent
permitted by Applicable Law.

     19.10  GOOD FAITH PERFORMANCE. Each Party shall act in good faith in its
performance under this Agreement and, in each case in which a Party's consent or
agreement is required or requested hereunder, such Party shall not unreasonably
withhold or delay such consent or agreement, as the case may be.

     19.11  RESPONSIBILITY TO CUSTOMERS. Each Party is solely responsible to its
Customers for the services it provides to such Customers.

     19.12  UNNECESSARY FACILITIES. No Party shall construct facilities which
require another Party to build unnecessary facilities.

                                      75
<PAGE>
 
     19.13   COOPERATION. The Parties shall work cooperatively to minimize fraud
associated with third-number billed calls, calling card calls, and any other
services related to this Agreement.

     19.14   NXX CODE ADMINISTRATION. Each Party is responsible for
administering NXX codes assigned to it.

     19.15   LERG LISTINGS. Each Party is responsible for obtaining Local
Exchange Routing Guide ("LERG") listings of CLLI codes assigned to its switches.

     19.16   LERG USE. Each Party shall use the LERG published by Bellcore or
its successor for obtaining routing information and shall provide all required
information to Bellcore for maintaining the LERG in a timely manner.

     19.17   SWITCH PROGRAMMING. Each Party shall program and update its own
Central Office Switches and End Office Switches and network systems to recognize
and route traffic to and from the other Party's assigned NXX codes. Except as
mutually agreed or as otherwise expressly defined in this Agreement, neither
Party shall impose any fees or charges on the other Party for such activities.

     19.18   TRANSPORT FACILITIES. Each Party is responsible for obtaining
transport facilities sufficient to handle traffic between its network and the
other Party's network. Each Party may provide the facilities itself, order them
through a third party, or order them from the other Party.

                                  ARTICLE XX
                            PROPRIETARY INFORMATION

     20.1    DEFINITION OF PROPRIETARY INFORMATION.

             20.1.1  "PROPRIETARY INFORMATION" means:

             (a)    all proprietary or confidential information of a Party (a
                    "DISCLOSING PARTY") including specifications, drawings,
                    sketches, business information, forecasts, records
                    (including each Party's records regarding Performance
                    Benchmarks), Customer Proprietary Network Information,
                    Customer Usage Data, audit information, models, samples,
                    data, system interfaces, computer programs and other
                    software and documentation that is furnished or made
                    available or otherwise disclosed to the other Party or any
                    of such other Party's Affiliates (individually and
                    collectively, a "RECEIVING PARTY") pursuant to this
                    Agreement and, if written, is marked "Confidential" or
                    "Proprietary" or by other similar notice or if oral or
                    visual, is identified as "Confidential" or "Proprietary" at
                    the time of disclosure; and

                                       76
<PAGE>
 
             (b)    any portion of any notes, analyses, data, compilations,
                    studies, interpretations or other documents prepared by any
                    Receiving Party to the extent the same contain, reflect, are
                    derived from, or are based upon, any of the information
                    described in subsection (a) above, unless such information
                    contained or reflected in such notes, analyses, etc. is so
                    commingled with the Receiving Party's information that
                    disclosure could not possibly disclose the underlying
                    proprietary or confidential information (such portions of
                    such notes, analyses, etc. referred to herein as "DERIVATIVE
                    INFORMATION").

             20.1.2 The Disclosing Party will use its reasonable efforts to
follow its customary practices regarding the marking of tangible Proprietary
Information as "confidential," "proprietary," or other similar designation. The
Parties agree that the designation in writing by the Disclosing Party that
information is confidential or proprietary shall create a presumption that such
information is confidential or proprietary to the extent such designation is
reasonable.

             20.1.3 Notwithstanding the requirements of this ARTICLE XX, all
                                                             ----------
information relating to the Customers of a Party, including information that
would constitute Customer Proprietary Network Information of a Party pursuant to
the Act and FCC rules and regulations, and Customer Usage Data, whether
disclosed by one Party to the other Party or otherwise acquired by a Party in
the course of the performance of this Agreement, shall be deemed "PROPRIETARY
INFORMATION."

       20.2  DISCLOSURE AND USE.

             20.2.1 Each Receiving Party agrees that from and after the
                    Effective Date:/17/
                                    --

             (a)    all Proprietary Information communicated, whether before,
                    on or after the Effective Date, to it or any of its
                    contractors, consultants or agents ("REPRESENTATIVES") in
                    connection with this Agreement shall be held in confidence
                    to the same extent as such Receiving Party holds its own
                    confidential information; provided that such Receiving
                                              --------
                    Party or Representative shall not use less than a
                    reasonable standard of care in maintaining the
                    confidentiality of such information;

             (b)    it will not, and it will not permit any of its employees, 
                    Affiliates or Representatives to disclose such Proprietary
                    Information to any third person;

________________________________

/17/   Since the terms of this Agreement are the result of Focal's adoption
 --
       under Section 252(i) of the Act of the AT&T Agreement, the Parties agree
       that the term "Effective Date", for purposes of this SECTION 20.2.1,
                                                            --------------
       shall mean February 10, 1999.

                                      77
<PAGE>
 
             (c)     it will disclose Proprietary Information only to those of
                     its employees, Affiliates and Representatives who have a
                     need for it in connection with the use or provision of
                     services required to fulfill this Agreement; and

             (d)     it will, and will cause each of its employees, Affiliates
                     and Representatives to use such Proprietary Information
                     only to perform its obligations under this Agreement or to
                     use services provided by the Disclosing Party hereunder and
                     for no other purpose, including its own marketing purposes.

             20.2.2  A Receiving Party may disclose Proprietary Information of a
Disclosing Party to its Representatives who need to know such information to
perform their obligations under this Agreement; provided that before disclosing
                                                -------- 
any Proprietary Information to any Representative, such Party shall notify such
Representative of such person's obligation to comply with this Agreement. Any
Receiving Party so disclosing Proprietary Information shall be responsible for
any breach of this Agreement by any of its Representatives and such Receiving
Party agrees, at its sole expense, to use its reasonable efforts (including
court proceedings) to restrain its Representatives from any prohibited or
unauthorized disclosure or use of the Proprietary Information. Each Receiving
Party making such disclosure shall notify the Disclosing Party as soon as
possible if it has knowledge of a breach of this Agreement in any material
respect. A Disclosing Party shall not disclose Proprietary Information directly
to a Representative of the Receiving Party without the prior written
authorization of the Receiving Party.

             20.2.3  Proprietary Information shall not be reproduced by any
Receiving Party in any form except to the extent (i) necessary to comply with
the provisions of SECTION 20.3 and (ii) reasonably necessary to perform its
                  ------------                                             
obligations under this Agreement. All such reproductions shall bear the same
copyright and proprietary rights notices as are contained in or on the original.

             20.2.4  This SECTION 20.2 shall not apply to any Proprietary
                          ------------                                   
Information which the Receiving Party can establish to have:

             (a)     been disclosed by the Receiving Party with the Disclosing
                     Party's prior written consent;

             (b)     become generally available to the public other than as a
                     result of disclosure by a Receiving Party;

             (c)     been independently developed by a Receiving Party by an
                     individual who has not had knowledge of or direct or
                     indirect access to such Proprietary Information;

             (d)     been rightfully obtained by the Receiving Party from a
                     third person without knowledge that such third person is
                     obligated to protect its

                                      78
<PAGE>
 
                    confidentiality; provided that such Receiving Party has no
                                     --------
                    reasonable basis on which to inquire as to whether or not
                    such information was subject to a confidentiality agreement
                    at the time such information was acquired; or

             (e)     been obligated to be produced or disclosed by Applicable
                     Law; provided that such production or disclosure shall have
                          --------
                     been made in accordance with SECTION 20.3.
                                                  ------------

     20.3    GOVERNMENT DISCLOSURE.

             20.3.1 If a Receiving Party desires to disclose or provide to the
Commission, the FCC or any other governmental authority any Proprietary
Information of the Disclosing Party, such Receiving Party shall, prior to and as
a condition of such disclosure, (i) provide the Disclosing Party with written
notice and the form of such proposed disclosure as soon as possible but in any
event early enough to allow the Disclosing Party to protect its interests in the
Proprietary Information to be disclosed and (ii) attempt to obtain in accordance
with the applicable procedures of the intended recipient of such Proprietary
Information an order, appropriate protective relief or other reliable assurance
that confidential treatment shall be accorded to such Proprietary Information.

             20.3.2 If a Receiving Party is required by any governmental
authority or by Applicable Law to disclose any Proprietary Information, then
such Receiving Party shall provide the Disclosing Party with written notice of
such requirement as soon as possible and prior to such disclosure. Upon receipt
of written notice of the requirement to disclose Proprietary Information, the
Disclosing Party, at its expense, may then either seek appropriate protective
relief in advance of such requirement to prevent all or part of such disclosure
or waive the Receiving Party's compliance with this SECTION 20.3 with respect to
                                                    ------------                
all or part of such requirement.

             20.3.3 The Receiving Party shall use all commercially reasonable
efforts to cooperate with the Disclosing Party in attempting to obtain any
protective relief which such Disclosing Party chooses to seek pursuant to this
SECTION 20.3. In the absence of such relief, if the Receiving Party is legally
- ------------
compelled to disclose any Proprietary Information, then the Receiving Party
shall exercise all commercially reasonable efforts to preserve the
confidentiality of the Proprietary Information, including cooperating with the
Disclosing Party to obtain an appropriate order or other reliable assurance that
confidential treatment will be accorded the Proprietary Information.

     20.4    OWNERSHIP.

             20.4.1 All Proprietary Information, other than Derivative
Information, shall remain the property of the Disclosing Party, and all
documents or other tangible media delivered to the Receiving Party that embody
such Proprietary Information shall be, at the option of the

                                      79
<PAGE>
 
Disclosing Party, either promptly returned to Disclosing Party or destroyed,
except as otherwise may be required from time to time by Applicable Law (in
which case the use and disclosure of such Proprietary Information will continue
to be subject to this Agreement), upon the earlier of (i) the date on which the
Receiving Party's need for it has expired and (ii) the expiration or termination
of this Agreement (including any applicable Transition Period).

             20.4.2  At the request of the Disclosing Party, any Derivative
Information shall be, at the option of the Receiving Party, either promptly
returned to the Disclosing Party or destroyed, except as otherwise may be
required from time to time by Applicable Law (in which case the use and
disclosure of such Proprietary Information will continue to be subject to this
Agreement), upon the earlier of (i) the date on which the Receiving Party's need
for it has expired and (ii) the expiration or termination of this Agreement
(including any applicable Transition Period).

             20.4.3  The Receiving Party may at any time either return to the
Disclosing Party or destroy Proprietary Information.

             20.4.4  If destroyed, all copies shall be destroyed and upon the
written request of the Disclosing Party, the Receiving Party shall provide to
the Disclosing Party written certification of such destruction. The destruction
or return of Proprietary Information shall not relieve any Receiving Party of
its obligation to treat such Proprietary Information in the manner required by
this Agreement.

                                  ARTICLE XXI
                             TERM AND TERMINATION

     21.1    TERM. The initial term of this Agreement shall expire on January
29, 2000 (the "INITIAL TERM") which shall commence on the Effective Date. Upon
expiration of the Initial Term, this Agreement shall automatically be renewed
for additional one (1)-year periods (each, a "RENEWAL TERM") unless a Party
delivers to the other Party written notice of termination of this Agreement at
least one hundred twenty (120) days prior to the expiration of the Initial Term
or a Renewal Term.

     21.2    RENEGOTIATION OF CERTAIN TERMS. Notwithstanding the foregoing, upon
delivery of written notice at least one hundred twenty (120) days prior to the
expiration of the Initial Term or any Renewal Term, either Party may require
negotiations of the rates, prices and charges, terms, and conditions of the
services to be provided under this Agreement effective upon such expiration. If
the Parties are unable to satisfactorily negotiate such new rates, prices,
charges and terms within ninety (90) days of such written notice, either Party
may petition the Commission or take such other action as may be necessary to
establish appropriate terms. If prior to the applicable expiration date, the
Parties are unable to mutually agree on such new rates, prices, charges, terms
and conditions or the Commission does not issue its order, the

                                      80
<PAGE>
 
Parties agree that the rates, terms and conditions ultimately ordered by such
Commission or negotiated by the Parties shall be effective retroactive to such
expiration date.

     21.3    DEFAULT. When a Party believes that the other Party is in violation
of a material term or condition of this Agreement ("DEFAULTING PARTY"), it shall
provide written notice to such Defaulting Party of such violation prior to
commencing the dispute resolution procedures set forth in SECTION 28.3 and it
                                                          ------------
shall be resolved in accordance with the procedures established in SECTION 28.3.
                                                                   ------------

     21.4    TRANSITIONAL SUPPORT.

             21.4.1 In the event of the termination or expiration of this
Agreement for any reason, each Party agrees to maintain the level and quality of
services still being provided by it as of the date of termination or expiration
of this Agreement ("TRANSITION DATE"), and to cooperate reasonably in an orderly
and efficient transition to a successor provider.

             21.4.2 Each Party agrees (i) to furnish services during a period
for up to one (1) year (or such longer period as may be agreed by the Parties)
after the Transition Date ("TRANSITION PERIOD") on terms and conditions and at
charges that are the same as those in effect upon the Transition Date, and (ii)
to enter into an agreement with the other Party for a transition plan that
specifies the nature, extent, and schedule of the services to be provided during
such Transition Period. During the Transition Period, Ameritech and Focal will
cooperate in good faith to effect an orderly transition of service under this
Agreement. Ameritech and Focal agree to exercise their respective reasonable
efforts to avoid or minimize service disruptions or degradation in services
during such transition.

     21.5    PAYMENT UPON EXPIRATION OR TERMINATION. In the case of the
expiration or termination of this Agreement for any reason, each of the Parties
shall be entitled to payment for all services performed and expenses accrued or
incurred prior to such expiration or termination, provided that a Party is
                                                  --------
entitled to recover such expenses under the provisions of this Agreement.


                                 ARTICLE XXII
                 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NO PARTY MAKES OR
RECEIVES ANY WARRANTY, EXPRESS, IMPLIED OR STATUTORY, WITH RESPECT TO THE
SERVICES, CONDITIONS, AND PRODUCTS IT PROVIDES OR IS CONTEMPLATED TO PROVIDE
UNDER THIS AGREEMENT AND EACH PARTY DISCLAIMS THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND/OR OF FITNESS FOR A PARTICULAR PURPOSE.

                                      81
<PAGE>
 
                                 ARTICLE XXIII
                             CANCELLATION CHARGES
                                        
     Except as provided in SECTIONS 9.1.3 and 19.5.3, pursuant to a Bona Fide
                           --------------     ------                       
Request or as otherwise provided in any applicable tariff or contract referenced
herein, cancellation charges shall not be imposed upon, or payable by, either
Party.

                                 ARTICLE XXIV
                                 SEVERABILITY

     24.1 SEVERABILITY. If any provision of this Agreement shall be held to be
illegal, invalid or unenforceable, each Party agrees that such provision shall
be enforced to the maximum extent permissible so as to effect the intent of the
Parties, and the validity, legality and enforceability of the remaining
provisions of this Agreement shall not in any way be affected or impaired
thereby. If necessary to effect the intent of the Parties, the Parties shall
negotiate in good faith to amend this Agreement to replace the unenforceable
language with enforceable language that reflects such intent as closely as
possible.

     24.2 NON-CONTRAVENTION OF LAWS. Nothing in this Agreement shall be
construed as requiring or permitting either Party to contravene any mandatory
requirement of Applicable Law.

                                  ARTICLE XXV
                                INDEMNIFICATION
                                        
     25.1 GENERAL INDEMNITY RIGHTS. Each Party (the "INDEMNIFYING PARTY") shall
defend and indemnify the other Party, its officers, directors, employees and
permitted assignees (collectively, the "INDEMNIFIED PARTY") and hold such
Indemnified Party harmless against
                           
          (a)  any Loss to a third person arising out of: the negligent acts or
               omissions, or willful misconduct ("FAULT") by such Indemnifying
               Party or the Fault of its employees, agents and subcontractors;
               provided, however, that (1) with respect to employees or agents
               of the Indemnifying Party, such Fault occurs while performing
               within the scope of their employment, (2) with respect to
               subcontractors of the Indemnifying Party, such Fault occurs in
               the course of performing duties of the subcontractor under its
               subcontract with the Indemnifying Party, and (3) with respect to
               the Fault of employees or agents of such subcontractor, such
               Fault occurs while performing within the scope of their
               employment by the subcontractor with respect to such duties of
               the subcontractor under the subcontract; 
     
                                      82
<PAGE>
 
          (b)  any Loss arising from such Indemnifying Party's use of services
               offered under this Agreement, involving pending or threatened
               claims, actions, proceedings or suits ("CLAIMS"), claims for
               libel, slander, invasion of privacy, or infringement of
               Intellectual Property rights arising from the Indemnifying
               Party's own communications or the communications of such
               Indemnifying Party's Customers;

          (c)  any Loss arising from Claims for actual or alleged infringement
               of any Intellectual Property right of a third person to the
               extent that such Loss arises from an Indemnified Party's or an
               Indemnified Party's Customer's use of a service provided under
               this Agreement; provided, however, that an Indemnifying Party's
                               --------  -------
               obligation to defend and indemnify the Indemnified Party shall
               not apply in the case of (i) (A) any use by an Indemnified Party
               of a service (or element thereof) in combination with elements,
               services or systems supplied by the Indemnified Party or persons
               other than the Indemnifying Party or (B) where an Indemnified
               Party or its Customer modifies or directs the Indemnifying Party
               to modify such service and (ii) no infringement would have
               occurred without such combined use or modification;

          (d)  any and all penalties imposed upon the Indemnifying Party's
               failure to comply with the Communications Assistance to Law
               Enforcement Act of 1994 ("CALEA") and, at the sole cost and
               expense of the Indemnifying Party, any amounts necessary to
               modify or replace any equipment, facilities or services
               provided to the Indemnified Party under this Agreement to ensure
               that such equipment, facilities and services fully comply with
               CALEA; and
               
          (e)  any Loss arising from such Indemnifying Party's failure to comply
               with Applicable Law.

     25.2 INDEMNIFICATION PROCEDURES. Whenever a Claim shall arise for
indemnification under this ARTICLE XXV, the relevant Indemnified Party, as
                           -----------                                  
appropriate, shall promptly notify, the Indemnifying Party and request the
Indemnifying Party to defend the same. Failure to so notify, the
Indemnifying Party shall not relieve the Indemnifying Party of any
liability that the Indemnifying Party might have, except to the extent that such
failure prejudices the Indemnifying Party's ability to defend such Claim. The
Indemnifying Party shall have the right to defend against such liability or
assertion in which event the Indemnifying Party shall give written notice
to the Indemnified Party of acceptance of the defense of such Claim and the
identity of counsel selected by the Indemnifying Party. Until such time as
Indemnifying Party provides such written notice of acceptance of the defense of
such Claim, the Indemnified Party shall defend such Claim, at the expense of
the Indemnifying Party, subject to any right of the Indemnifying Party, to
seek reimbursement for the costs of such defense in the event that it is
determined that Indemnifying Party had no obligation to indemnify the
Indemnified Party for

                                 83
<PAGE>
 
such Claim. The Indemnifying Party shall have exclusive right to control and
conduct the defense and settlement of any such Claims subject to consultation
with the Indemnified Party. The Indemnifying Party shall not be liable for any
settlement by the Indemnified Party unless such Indemnifying Party has approved
such settlement in advance and agrees to be bound by the agreement incorporating
such settlement. At any time, an Indemnified Party shall have the right to
refuse a compromise or settlement and, at such refusing Party's cost, to take
over such defense; provided that in such event the Indemnifying Party shall not
                   -------- 
be responsible for, nor shall it be obligated to indemnify the relevant
Indemnified Party against, any cost or liability in excess of such refused
compromise or settlement. With respect to any defense accepted by the
Indemnifying Party, the relevant Indemnified Party shall be entitled to
participate with the Indemnifying Party in such defense if the Claim requests
equitable relief or other relief that could affect the rights of the Indemnified
Party and also shall be entitled to employ separate counsel for such defense at
such Indemnified Party's expense. If the Indemnifying Party does not accept the
defense of any indemnified Claim as provided above, the relevant Indemnified
Party shall have the right to employ counsel for such defense at the expense of
the Indemnifying Party. Each Party agrees to cooperate and to cause its
employees and agents to cooperate with the other Party in the defense of any
such Claim and the relevant records of each Party shall be available to the
other Party with respect to any such defense, subject to the restrictions and
limitations set forth in ARTICLE XX.
                         ----------


                                 ARTICLE XXVI
                            LIMITATION OF LIABILITY
   
     26.1 LIMITED RESPONSIBILITY. Each Party shall be responsible only for
service(s) and facility(ies) which are provided by that Party, its authorized
agents, subcontractors, or others retained by such parties, and neither Party
shall bear any responsibility for the services and facilities provided by the
other Party, its Affiliates, agents, subcontractors, or other persons retained
by such parties. No Party shall be liable for any act or omission of another
Telecommunications Carrier (other than an Affiliate) providing a portion of a
service.

     26.2 APPORTIONMENT OF FAULT. In the case of any Loss arising from the
negligence or willful misconduct of both Parties, each Party shall bear, and its
obligation shall be limited to, that portion of the resulting expense caused by
its negligence or misconduct of such Party's Affiliates, agents, contractors or
other persons acting in concert with it.

     26.3 LIMITATION OF DAMAGES. Except for indemnity obligations under ARTICLE
                                                                        -------
XXV, each Party's liability to the other Party for any Loss relating to or
- ---
arising out of any negligent act or omission in its performance of this
Agreement, whether in contract, tort or otherwise, shall be limited to the
total amount properly charged to the other Party by such negligent or breaching
Party for the service(s) or function(s) not performed or improperly
performed. Notwithstanding the foregoing, in cases involving any Claim for a
Loss associated with the installation, provision, termination, maintenance,
repair or restoration of an individual Network Element or

                                 84
<PAGE>
 
Combination or a Resale Service provided for a specific Customer of the other
Party, the negligent or breaching Party's liability shall be limited to the
greater of: (i) the total amount properly charged to the other Party for the
service or function not performed or improperly performed and (ii) the amount
such negligent or breaching Party would have been liable to its Customer if the
comparable retail service was provided directly to its Customer.

     26.4 LIMITATIONS IN TARIFFS. Each Party may, in its sole discretion,
provide in its tariffs and contracts with its Customers or third parties that
relate to any service, product or function provided or contemplated under this
Agreement that, to the maximum extent permitted by Applicable Law, such Party
shall not be liable to such Customer or third party for (i) any Loss relating
to or arising out of this Agreement, whether in contract, tort or otherwise,
that exceeds the amount such Party would have charged the applicable person for
the service, product or function that gave rise to such Loss and (ii) any
Consequential Damages (as defined in Section 26.5). To the extent a Party elects
not to place in its tariffs or contracts such limitation(s) of liability, and
the other Party incurs a Loss as a result thereof, such Party shall indemnify
and reimburse the other Party for that portion of the Loss that would have been
limited had the first Party included in its tariffs and contracts the
limitation(s) of liability that such other Party included in its own tariffs at
the time of such Loss.

     26.5 CONSEQUENTIAL DAMAGES. In no event shall either Party have any
liability whatsoever to the other Party for any indirect, special,
consequential, incidental or punitive damages, including loss of anticipated
profits or revenue or other economic loss in connection with or arising from
anything said, omitted or done hereunder (collectively, "CONSEQUENTIAL
DAMAGES"), even if the other Party has been advised of the possibility of such
damages; provided that the foregoing shall not limit a Party's obligation under
         --------
SECTION 25.1 to indemnify, defend and hold the other Party harmless against any
- ------------
amounts payable to a third person, including any losses, costs, fines,
penalties, criminal or civil judgments or settlements, expenses (including
attorneys' fees) and Consequential Damages of such third person.

     26.6 REMEDIES. Except as expressly provided herein, no remedy set forth in
this Agreement is intended to be exclusive and each and every remedy shall be
cumulative and in addition to any other rights or remedies now or hereafter
existing under applicable law or otherwise.

                                 ARTICLE XXVII
                                    BILLING
                                        
     27.1 BILLING.

          27.1.1 Each Party will bill all applicable charges, at the rates
set forth herein, in the Pricing Schedule and as set forth in applicable
tariffs or contracts referenced herein, for the services provided by that Party
to the other Party in accordance with this ARTICLE XXVII and the Implementation
                                           -------------  
Plan.

                                 85
<PAGE>
 
          27.1.2 The Parties agree that in order to ensure the proper
performance and integrity of the entire billing process, each Party will be
responsible and accountable for transmitting to the other Party an accurate and
current bill. Each Party agrees to implement control mechanisms and procedures
to render a bill that accurately reflects the services ordered and used by the
other Party.

     27.2 RECORDING. To the extent technically feasible, the Parties shall
record all available call detail information associated with calls originated or
terminated to the other Party, in accordance with the Implementation Plan and as
specifically required herein.

     27.3 PAYMENT OF CHARGES. Subject to the terms of this Agreement, Focal and
Ameritech will pay each other within forty-five (45) calendar days from the date
of an invoice (the "BILL DUE DATE"). If the Bill Due Date is on a day other than
a Business Day, payment will be made on the next Business Day. Payments shall be
made in U.S. Dollars via electronic funds transfer ("EFT") to the other 
Party's bank account. Within thirty (30) days of the Effective Date, /18/ the
                                                                      --
Parties shall provide each other the name and address of its bank, its account
and routing number and to whom payments should be made payable. If such banking
information changes, each Party shall provide the other Party at least sixty
(60) days' written notice of the change and such notice shall include the new
banking information. If a Party receives multiple invoices which are payable on
the same date, such Party may remit one payment for the sum of all amounts
payable to the other Party's bank. Each Party shall provide the other Party with
a contact person for the handling of payment questions or problems.

     27.4 LATE PAYMENT CHARGES. If either Party fails to remit payment for any
charges for services by the Bill Due Date, or if a payment or any portion of
a payment is received by either Party after the Bill Due Date, or if a payment
or any portion of a payment is received in funds which are not immediately
available to the other Party as of the Bill Due Date, then a late payment
penalty shall be assessed. The portion of the payment not received by the Bill
Due Date shall accrue interest as provided in SECTION 27.6. In no event,
                                              ------------
however, shall interest be assessed on any previously assessed late payment
charges.

     27.5 ADJUSTMENTS. 

          27.5.1  A Party shall promptly reimburse or credit the other Party for
any charges that should not have been billed to the other Party as provided 
in this Agreement. Such reimbursements shall be set forth in the appropriate
section of the invoice.

          27.5.2  A Party shall bill the other Party for any charges that should
have been billed to the other Party as provided in this Agreement, but have not
been billed to the other

______________________

/18/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 27.3, shall mean
                                                     ------------
     February 10, 1999.

                                      86
<PAGE>
 
Party ("UNDERBILLED CHARGES"); provided, however, that, except as provided in
                               --------  -------
ARTICLE XXVIII, the Billing Party shall not bill for Underbilled Charges which
- --------------
were incurred more than one (1) year prior to the date that the Billing Party
transmits a bill for any Underbilled Charges. Notwithstanding the foregoing,
Focal shall not be liable for any Underbilled Charges for which Customer Usage
Data was not furnished by Ameritech to Focal within ten (10) months of the date
such usage was incurred.

     27.6 INTEREST ON UNPAID AMOUNTS. Any undisputed amounts not paid when due
shall accrue interest from the date such amounts were due at the lesser of (i)
one and one-half percent (1 1/2%) per month or (ii) the highest rate of
interest that may be charged under Applicable Law, compounded daily from the
number of days from the Bill Due Date to and including the date that payment is
actually made.


                                ARTICLE XXVIII
                        AUDIT RIGHTS, DISPUTED AMOUNTS
                            AND DISPUTE RESOLUTION
                                        
     28.1 AUDIT RIGHTS.
           
          28.1.1 Subject to the restrictions set forth in ARTICLE XX and except
                                                          ----------
as may be otherwise specifically provided in this Agreement, a Party ("AUDITING
PARTY") may audit the other Party's ("AUDITED PARTY") books, records, data and
other documents, as provided herein, once each Contract Year for the purpose of
evaluating the accuracy of Audited Party's billing and invoicing. The scope of
the audit shall be limited to the services provided and purchased by the Parties
and the associated charges, books, records, data and other documents relating
thereto for the period which is the shorter of (i) the period subsequent to the
last day of the period covered by the Audit which was last performed (or if no
audit has been performed, the Effective Date /19/ and (ii) the twenty-four (24)
                                              --
month period immediately preceding the date the Audited Party received notice of
such requested audit. Such audit shall begin no fewer than thirty (30) days
after Audited Party receives a written notice requesting an audit and shall be
completed no later than thirty (30) days after the start of such audit. Such
audit shall be conducted by an independent auditor acceptable to both Parties.
The Parties shall select an auditor by the thirtieth day following Audited
Party's receipt of a written audit notice. Auditing Party shall cause the
independent auditor to execute a nondisclosure agreement in a form agreed upon
by the Parties. Notwithstanding the foregoing, an Auditing Party may audit
Audited Party's books, records and documents more than once during any Contract
Year if the previous audit found previously uncorrected net variances or errors
in invoices in Audited Party's favor with an aggregate value

______________________

/19/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 28.1.1, shall mean
                                                     --------------
     February 10, 1999.

                                      87
<PAGE>
 
of at least two percent (2%) of the amounts payable by Auditing Party for
audited services provided during the period covered by the audit.

          28.1.2 Each audit shall be conducted on the premises of Audited Party
during normal business hours. Audited Party shall cooperate fully in any such
audit, providing the independent auditor reasonable access to any and all
appropriate Audited Party employees and books, records and other documents
reasonably necessary to assess the accuracy of Audited Party's bills. No Party
shall have access to the data of the other Party, but shall rely upon summary
results provided by the independent auditor. Audited Party may redact from the
books, records and other documents provided to the independent auditor any
confidential Audited Party information that reveals the identity of other
Customers of Audited Party. Each Party shall maintain reports, records and data
relevant to the billing of any services that are the subject matter of this
Agreement for a period of not less than twenty-four (24) months after creation
thereof, unless a longer period is required by Applicable Law.

          28.1.3 If any audit confirms any undercharge or overcharge, then
Audited Party shall (i) for any overpayment promptly correct any billing error,
including making refund of any overpayment by Auditing Party in the form of a
credit on the invoice for the first full billing cycle after the Parties have
agreed upon the accuracy of the audit results and (ii) for any undercharge
caused by the actions of or failure to act by the Audited Party, immediately
compensate Auditing Party for such undercharge, in each case with interest at
the lesser of (x) one and one-half (1 1/2%) percent per month and (y) the
highest rate of interest that may be charged under Applicable Law, compounded
daily, for the number of days from the date on which such undercharge or
overcharge originated until the date on which such credit is issued or payment
is made and available, as the case may be. Notwithstanding the foregoing, Focal
shall not be liable for any Underbilled Charges for which Customer Usage Data
was not furnished by Ameritech to Focal within ten (10) months of the date such
usage was incurred.

          28.1.4 Audits shall be at Auditing Party's expense, subject to
reimbursement by Audited Party in the event that an audit finds, and the Parties
subsequently verify, adjustment in the charges or in any invoice paid or payable
by Auditing Party hereunder by an amount that is, on an annualized basis,
greater than two percent (2%) of the aggregate charges for the audited services
during the period covered by the audit.

           28.1.5 Any Disputes concerning audit results shall be referred to the
Parties' respective responsible personnel for informal resolution. If these
individuals cannot resolve the Dispute within thirty (30) days of the referral,
either Party may request in writing that an additional audit shall be conducted
by an independent auditor acceptable to both Parties, subject to the
requirements set out in SECTION 28.1.1. Any additional audit shall be at the
                        -------------- 
requesting Party's expense.

                                      88
<PAGE>
 
     28.2 DISPUTED AMOUNTS.

          28.2.1 If any portion of an amount due to a Party (the "BILLING
PARTY") under this Agreement is subject to a bona fide dispute between the
Parties, the Party billed (the "NON-PAYING PARTY") shall, prior to the Bill Due
Date, give written notice to the Billing Party of the amounts it disputes
("DISPUTED AMOUNTS") and include in such written notice the specific details and
reasons for disputing each item; provided, however, a failure to provide such
                                 --------  -------
notice by that date shall not preclude a Party from subsequently challenging
billed charges. The Non-Paying Party shall pay when due all undisputed amounts
to the Billing Party. Notwithstanding the foregoing, except as provided in
SECTION 28.1, a Party shall be entitled to dispute only those charges for which
- ------------
the Bill Due Date was within the immediately preceding twelve (12) months of the
date on which the other Party received notice of such Disputed Amounts.

          28.2.2 If the Non-Paying Party disputes a charge and does not pay such
Disputed Amounts by the Bill Due Date, such Disputed Amounts shall be subject to
late payment charges as set forth in SECTION 27.4. If the Non-Paying Party
                                     ------------
disputes charges and the dispute is resolved in favor of such Non-Paying Party,
the Billing Party shall credit the invoice of the Non-Paying Party for the
amount of the Disputed Amounts along with any applicable late payment charges
assessed no later than the second Bill Due Date after the resolution of the
Dispute. Accordingly, if a Non-Paying Party disputes charges and the dispute is
resolved in favor of the Billing Party, the Non-Paying Party shall pay the
Billing Party the amount of the Disputed Amounts and any associated late payment
charges assessed no later than the second Bill Due Date after the resolution of
the Dispute. In no event, however, shall any late payment charges be assessed on
any previously assessed late payment charges.

          28.2.3 If the Parties are unable to resolve the issues related to the
Disputed Amounts in the normal course of business within sixty (60) days after
delivery to the Billing Party of notice of the Disputed Amounts, each of the
Parties shall appoint a designated representative who has authority to settle
the Dispute and who is at a higher level of management than the persons with
direct responsibility for administration of this Agreement. The designated
representatives shall meet as often as they reasonably deem necessary in order
to discuss the Dispute and negotiate in good faith in an effort to resolve such
Dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

          28.2.4 If the Parties unable to resolve issues related to the Disputed
Amounts within forty-five (45) days after the Parties' appointment of designated
representatives pursuant to SECTION 28.3, then either Party may file a complaint
                            ------------
with the Commission to resolve such issues or proceed with any other remedy
pursuant to law or equity. The Commission or the FCC may direct payment of 
any or all Disputed Amounts (including any accrued interest) thereon or
additional amounts awarded plus applicable late fees, to be paid to either
Party.

                                 89
<PAGE>
 
          28.2.5 The Parties agree that all negotiations pursuant to this
SECTION 28.2 shall remain confidential in accordance with ARTICLE XX and shall
- ------------                                              ----------
be treated as compromise and settlement negotiations for purposes of the Federal
Rules of Evidence and state rules of evidence.

     28.3 DISPUTE ESCALATION AND RESOLUTION. Except as otherwise provided
herein, any dispute, controversy or claim (individually and collectively, a
"DISPUTE") arising under this Agreement shall be resolved in accordance with the
procedures set forth in this SECTION 28.3. In the event of a Dispute between the
                             ------------
Parties relating to this Agreement and upon the written request of either Party,
each of the Parties shall appoint a designated representative who has authority
to settle the Dispute and who is at a higher level of management than the
persons with direct responsibility for administration of this Agreement. The
designated representatives shall meet as often as they reasonably deem necessary
in order to discuss the Dispute and negotiate in good faith in an effort to
resolve such Dispute. The specific format for such discussions will be left to
the discretion of the designated representatives, however, all reasonable
requests for relevant information made by one Party to the other Party shall be
honored. If the Parties are unable to resolve issues related to a Dispute within
thirty (30) days after the Parties' appointment of designated representatives as
set forth above, the Parties shall attempt in good faith to address any default
or resolve any Dispute according to the rules, guidelines or regulations of the
Commission (and any procedures available to a Telecommunications provider under
the Michigan Telecommunications Act). Nowithstanding the foregoing, in no event
shall the Parties permit the pending of a Dispute to disrupt service to any
Focal Customer or Ameritech Customer.

     28.4 EQUITABLE RELIEF. Nowithstanding the foregoing, this ARTICLE XXVIII
                                                               --------------
shall not be construed to prevent either Party from seeking and obtaining
temporary equitable remedies, including temporary restraining orders, if, in its
judgment, such action is necessary to avoid irreparable harm. Despite any such
action, the Parties will continue to participate in good faith in the dispute
resolution procedures described in this ARTICLE XXVIII.
                                        --------------

                                 ARTICLE XXIX
                              REGULATORY APPROVAL

     29.1 COMMISSION APPROVAL.

     The Parties understand and agree that this Agreement will be filed with the
Commission for approval by such Commission (or the FCC if the Commission fails
to act) pursuant to Section 252 of the Act. Each Party agrees that this
Agreement is satisfactory to them as an agreement under Sections 251 and 252
of the Act. Each Party agrees to fully support approval of this Agreement by the
Commission (or the FCC) under Section 252 of the Act without modification; 
provided, however, that each Party may exercise its right to judicial review
- --------  -------
under Section 252(e)(6) of the Act, or any other available remedy at law or
equity, with respect to any matter included herein by arbitration under the Act
over the objection of such Party. If the

                                 90
<PAGE>
 
Commission, the FCC or any court rejects any portion of this Agreement, the
Parties agree to meet and negotiate in good faith to arrive at a mutually
acceptable modification of the rejected portion and related provisions; provided
                                                                        --------
that such rejected portion shall not affect the validity of the remainder of
this Agreement. The Parties acknowledge that nothing in this Agreement shall
limit a Party's ability, independent of such Party's agreement to support and
participate in the approval of this Agreement, to assert public policy issues
relating to the Act.

     29.2 TARIFFS. If either Party is required by any governmental authority to
file a tariff or make another similar filing to implement any provision of this
Agreement (other than a tariff filed by a Party that generally relates to one or
more services provided under this Agreement but not specifically to Focal or
Ameritech) (an "AMERITECH/FOCAL INTERCONNECT TARIFF"), such Party shall (i)
consult with the other Party reasonably in advance of such filing about the form
and substance of such Ameritech/Focal Interconnect Tariff, (ii) provide to such
other Party its proposed Ameritech/Focal Interconnect Tariff and obtain such
other Party's agreement on the form and substance of such Ameritech/Focal
Interconnect Tariff prior to such filing, and (iii) take all steps reasonably
necessary to ensure that such Ameritech/Focal Interconnect Tariff or other
filing imposes obligations upon such Party that are as close as possible to
those provided in this Agreement and preserves for such other Party the full
benefit of the rights otherwise provided in this Agreement. If, subsequent to
the effective date of any such Ameritech/Focal Interconnect Tariff, a Party is
no longer required to file tariffs with the Commission or the FCC, either
generally or for specific services, the Parties agree to modify this Agreement
to reflect herein the relevant and consistent terms and conditions of such
Ameritech/Focal Interconnect Tariffs as of the date on which the requirement to
file such Ameritech/Focal Interconnect Tariffs was lifted. Nothing in this
SECTION 29.2 shall be construed to grant a Party any right to review any tariff
- ------------
filing of the other Party other than the Ameritech/Focal Interconnection Tariff,
other than as provided under Applicable Law.

     29.3 AMENDMENT OR OTHER CHANGES TO THE ACT; RESERVATION OF RIGHTS. The
Parties acknowledge that the respective rights and obligations of each Party as
set forth in this Agreement are based on the text of the Act and the rules and
regulations promulgated thereunder by the FCC and the Commission as of the
Effective Date. In the event of any amendment of the Act, or any final and
nonappealable legislative, regulatory, judicial order, rule or regulation or
other legal action that revises or reverses the Act, the FCC's First Report and
Order in CC Docket Nos. 96-98 and 95-185 or any applicable Commission order or
arbitration award purporting to apply the provisions of the Act (individually
and collectively, an "AMENDMENT TO THE ACT"), either Party may by providing
written notice to the other Party require that the affected provisions be
renegotiated in good faith and this Agreement be amended accordingly to reflect
the pricing, terms and conditions of each such Amendment to the Act relating to
any of the provisions in this Agreement. If any such amendment to this Agreement
affects any rates or charges of the services provided hereunder, each Party
reserves its rights and remedies with respect to the collection of such rates or
charges on a retroactive basis, including the right to seek a surcharge before
the applicable regulatory authority.

                                 91
<PAGE>
 
     29.4 REGULATORY CHANGES. If any final and nonappealable legislative,
regulatory, judicial or other legal action (other than an Amendment to the Act,
which is provided for in SECTION 29.3) materially affects the ability of a Party
                         ------------
to perform any material obligation under this Agreement, a Party may, on thirty
(30) days' written notice (delivered not later than thirty (30) days following
the date on which such action has become legally binding and has otherwise
become final and nonappealable), require that the affected provision(s) be
renegotiated, and the Parties shall renegotiate in good faith such mutually
acceptable new provision(s) as may be required; provided that such affected
                                                --------
provisions shall not affect the validity of the remainder of this Agreement.

     29.5 PROXY RATES. In the event the initial rates under this Agreement are
"proxy rates" established by the FCC or the Commission, the Parties are to
substitute rates later established by the FCC or Commission under procedures
consistent with the Act and any Order of the FCC or Commission.

                                  ARTICLE XXX
                                 MISCELLANEOUS
                                        
     30.1 AUTHORIZATION.

          30.1.1 Ameritech Services, Inc. is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware.
Ameritech Information Industry Services, a division of Ameritech Services, Inc.
has full power and authority to execute and deliver this Agreement and to
perform the obligations hereunder on behalf of and as agent for Ameritech
Michigan.

          30.1.2 Focal is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware and has full power and
authority to execute and deliver this Agreement and to perform its obligations
hereunder. Focal represents and warrants to Ameritech that it has been certified
as an LEC by the Commission and is authorized to provide in the State of
Delaware the services it has contracted to provide herein.

     30.2 DESIGNATION OF AFFILIATE. Each Party may without the consent of the
other Party fulfill its obligations under this Agreement by itself or may cause
its Affiliates to take some or all of such actions to fulfill such obligations.
Upon such designation, the Affiliate shall become a primary obligor hereunder
with respect to the delegated matter, but such designation shall not relieve the
designating Party of its obligations as primary obligor hereunder. Any Party
which elects to perform its obligations through an Affiliate shall cause its
Affiliate to take all action necessary for the performance hereunder of such
Party's obligations. Each Party represents and warrants that if an obligation
under this Agreement is to be performed by an Affiliate, such Party has the
authority to cause such Affiliate to perform such obligation and such Affiliate
will have the resources required to accomplish the delegated performance.

                                      92
<PAGE>
 
     30.3 SUBCONTRACTING. Either Party may subcontract the performance of its
obligation under this Agreement without the prior written consent of the other
Party; provided, however, that the Party subcontracting such obligation shall
       --------  -------
remain fully responsible for the performance of such obligation and be solely
responsible for payments due its subcontractors.

     30.4 INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder as
an independent contractor and nothing herein shall be construed as creating any
other relationship between the Parties. Each Party and each Party's contractor
shall be solely responsible for the withholding or payment of all applicable
federal, state and local income taxes, social security taxes and other payroll
taxes with respect to their employees, as well as any taxes, contributions or
other obligations imposed by applicable state unemployment or workers'
compensation acts. Each Party has sole authority and responsibility to hire,
fire and otherwise control its employees.

     30.5 FORCE MAJEURE. No Party shall be responsible for delays or failures in
performance of any part of this Agreement (other than an obligation to make
money payments) resulting from acts or occurrences beyond the reasonable control
of such Party, including acts of nature, acts of civil or military authority,
any law, order, regulation, ordinance of any government or legal body,
embargoes,epidemics, terrorist acts, riots, insurrections, fires, explosions,
earthquakes, nuclear accidents, floods, work stoppages, equipment failures,
power blackouts, volcanic action, other major environmental disturbances,
unusually severe weather conditions, inability to secure products or services of
other persons or transportation facilities or acts or omissions of
transportation carriers (individually or collectively, a "FORCE MAJEURE EVENT")
or delays caused by the other Party or any other circumstances beyond the
Party's reasonable control. If a Force Majeure Event shall occur, the Party
affected shall give prompt notice to the other Party of such Force Majeure Event
specifying the nature, date of inception and expected duration of such Force
Majeure Event, whereupon such obligation or performance shall be suspended to
the extent such Party is affected by such Force Majeure Event during the
continuance thereof or be excused from such performance depending on the nature,
severity and duration of such Force Majeure Event (and the other Party shall
likewise be excused from performance of its obligations to the extent such
Party's obligations relate to the performance so interfered with). The affected
Party shall use its reasonable efforts to avoid or remove the cause of
nonperformance and the Parties shall give like notice and proceed to perform
with dispatch once the causes are removed or cease. Notwithstanding the
preceding, no delay or other failure to perform shall be excused pursuant to
this SECTION 30.5 (i) by the acts or omission of a Party's subcontractors,
     ------------
materialmen, suppliers or other third persons providing products or services to
such Party unless such acts or omissions are themselves the product of a Force
Majeure Event, and unless such delay or failure and the consequences thereof are
beyond the control and without the fault or negligence of the Party claiming
excusable delay or other failure to perform, or (ii) if such Party fails to
implement any steps taken to mitigate the effects of a Force Majeure Event e.g.,
                                                                           ----
disaster recovery plans) in a nondiscriminatory manner during the period
performance is impaired.

     30.6 GOVERNING LAW. For all claims under this Agreement that are based upon
issues within the jurisdiction (primary or otherwise) of the FCC, the exclusive
jurisdiction and remedy

                                      91
        
<PAGE>
 
for all such claims shall be as provided for by the FCC and the Act. For all
claims under this Agreement that are based upon issues within the jurisdiction
(primary or otherwise) of the Commission, the exclusive jurisdiction for all
such claims shall be with such Commission, and the exclusive remedy for such
claims shall be as provided for by such Commission. In all other respects, this
Agreement shall be governed by the domestic laws of the State of Michigan
without reference to conflict of law provisions; provided, however, that the
                                                 --------  -------
Parties shall consult with each other and attempt to agree on a common state law
to govern an issue that affects each of the Regional Interconnection Agreements
and such issue is not particular to a specific State's law.

     30.7 TAXES.

          30.7.1 Each Party purchasing services hereunder shall pay or otherwise
be responsible for all federal, state, or local sales, use, excise, gross
receipts, transaction or similar taxes, fees or surcharges levied against or
upon such purchasing Party (or the providing Party when such providing Party is
permitted to pass along to the purchasing Party such taxes, fees or surcharges),
except for any tax on either Party's corporate existence, status or income.
Whenever possible, these amounts shall be billed as a separate item on the
invoice. To the extent a sale is claimed to be for resale, the purchasing Party
shall furnish the providing Party a proper resale tax exemption certificate as
authorized or required by statute or regulation by the jurisdiction providing
said resale tax exemption. Failure to timely provide said resale tax exemption
certificate will result in no exemption being available to the purchasing Party
for any changes invoiced prior to the date such exemption certificate is
furnished. To the extent that a Party includes gross receipts taxes in any of
the charges or rates of services provided hereunder, no additional gross
receipts taxes shall be levied against or upon the purchasing Party.
 
          30.7.2 The Party obligated to pay any such taxes may contest the same
in good faith, at its own expense, and shall be entitled to the benefit of any
refund or recovery, provided that such contesting Party shall not permit any
                    --------
lien to exist on any asset of the other Party by reason of such contest. The
Party obligated to collect and remit shall cooperate in any such contest by the
other Party. As a condition of contesting any taxes due hereunder, the
contesting Party agrees to be liable and indemnify and reimburse the other Party
for any additional amounts that may be due by reason of such contest, including
any interest and penalties.

     30.8 NON-ASSIGNMENT. Neither Party may assign or transfer (whether by
operation of law or otherwise) this Agreement (or any rights or obligations
hereunder) to a third person without the prior written consent of the other
Party; provided that each Party may assign or transfer this Agreement to an
       --------
Affiliate in accordance with SECTION 30.2 by providing prior written notice to
                             ------------ 
the other Party of such assignment or transfer; provided, further, that such
                                                --------  -------
assignment is not inconsistent with Applicable Law or the terms and conditions
of this Agreement. Any attempted assignment or transfer that is not permitted is
void ab initio. Without limiting the generality of the foregoing, this Agreement
     -- ------
shall be binding upon and shall inure to the benefit of the Parties' respective
successors and assigns and the assigning Party will remain liable for the
performance of any assignee.

                                      94
<PAGE>
 
     30.9  NON-WAIVER. Failure of either Party to insist on performance of any
term or condition of this Agreement or to exercise any right or privilege
hereunder shall not be construed as a continuing or future waiver of such term,
condition, right or privilege.

     30.10 NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing (unless specifically provided otherwise herein)
and unless otherwise specifically required by this Agreement to be delivered to
another representative or point of contact, shall be (a) delivered personally,
(b) delivered by express delivery service, (c) mailed, certified mail or first
class U.S. mail postage prepaid, return receipt requested or (d) delivered by
telecopy; provided that a confirmation copy is sent by the method described in
          --------
(a), (b) or (c) of this SECTION 30.10, to the following addresses of the
                        -------------
Parties:


          To Focal:
          
          Focal Communications Corporation of Michigan
          200 N. LaSalle Street
          Suite 800
          Chicago, Illinois 60601
          Attn: Director Regulatory Affairs
          
          To Ameritech:
          
          Ameritech Information Industry Services
          350 North Orleans, Floor 3
          Chicago, IL 60654
          Attn: Vice President - Network Providers 
          Facsimile: (312)335-2927
          
          with a copy to:
          
          Ameritech Information Industry Services
          350 North Orleans, Floor 5
          Chicago, IL 60654
          Attn: Vice President and General Counsel
          Facsimile: (312)245-0254

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual
receipt, (ii) the next business day when notice is sent via express mail or
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail or (iv) on the date set forth on the confirmation in the
case of telecopy.

                                      95
<PAGE>
 
     30.11 PUBLICITY AND USE OF TRADEMARKS OR SERVICE MARKS.

Neither Party nor its subcontractors or agents shall use the other Party's
trademarks, service marks, logos or other proprietary trade dress in any
advertising, press releases, publicity matters or other promotional materials
without such Party's prior written consent, except as permitted by Applicable
Law.

     30.12 NONEXCLUSIVE DEALINGS.

This Agreement does not prevent either Party from providing or purchasing
services to or from any other person nor, except as provided in Section 2.52(i)
of the Act, does it obligate either Party to provide or purchase any services
not specifically provided herein.

     30.13 NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. Except as may be
specifically set forth in this Agreement, this Agreement is for the sole benefit
of the Parties and their permitted assigns, and nothing herein express or
implied shall create or be construed to create any third-party beneficiary
rights hereunder. Nothing in this Agreement shall constitute a Party as a legal
representative or agent of the other Party, nor shall a Party have the right or
authority to assume, create or incur any liability or any obligation of any
kind, express or implied, against or in the name or on behalf of the other Party
unless otherwise expressly permitted by such other Party. No Party undertakes to
perform any obligation of the other Party, whether regulatory or contractual, or
to assume any responsibility for the management of the other Party's business.

     30.14 NO LICENSE. No license under patents, copyrights or any other
Intellectual Property right (other than the limited license to use consistent
with the terms, conditions and restrictions of this Agreement) is granted either
Party or shall be implied or arise by estoppel with respect to any transactions
contemplated under this Agreement.

     30.15 SURVIVAL. The Parties' obligations under this Agreement which by
their nature are intended to continue beyond the termination or expiration of
this Agreement shall survive the termination or expiration of this Agreement,
including ARTICLES XX, XXI, XXII, XXIII, XXV, AND XXVI, SECTIONS 3.9.4, 6.5,
          -----------  ---  ----  -----  ---      ----  --------------  ---
10.11.3, 16.15, 16.17, 19.5.3, 28.2, 28.3, 30.7, 30.11, AND 30.14 AND SCHEDULE
- -------  -----  -----  ------  ----  ----  ----  -----      -----     --------
10.9.6.
- ------

      30.16 SCOPE OF AGREEMENT. This Agreement is intended to describe and
enable specific Interconnection and access to unbundled Network Elements and
compensation arrangements between the Parties. This Agreement does not obligate
either Party to provide arrangements not specifically provided herein. Except as
specifically contained herein or provided by the FCC or the Commission within
its lawful jurisdiction, nothing in this Agreement shall be deemed to affect any
access charge arrangement.

     30.17 COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original; but such counterparts
shall together constitute one and the same instrument.

                                      96
<PAGE>
 
     30.18 ENTIRE AGREEMENT. The terms contained in this Agreement and any
Schedules, Exhibits, tariffs and other documents or instruments referred to
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with respect to the subject matter
hereof, superseding all prior understandings, proposals and other
communications, oral or written. Specifically, the Parties expressly acknowledge
that the rates, terms and conditions of this Agreement shall supersede those
existing arrangements of the Parties, if any, set forth on SCHEDULE 30.18.
                                                           -------------- 
Neither Party shall be bound by any terms additional to or different from those
in this Agreement that may appear subsequently in the other Party's form
documents, purchase orders, quotations, acknowledgments, invoices or other
communications. This Agreement may only be modified by a writing signed by an
officer of each Party.


                                 ARTICLE XXXI
                             AMERITECH COLLOCATION
                                        
     31.1 PHYSICAL COLLOCATION.

     Focal shall provide to Ameritech Physical Collocation in the LEC Access
Equipment Room in Focal's Wire Centers for equipment necessary for
Interconnection (pursuant to ARTICLE III). Focal shall provide Ameritech
                             -----------
Collocation only for the purpose of such Interconnection.

     31.2 ELIGIBLE EQUIPMENT.

     Ameritech may Collocate equipment necessary for Interconnection of the same
type that it uses to provide total service access/20/ for Focal.
                                                  --

     31.3 TRANSMISSION FACILITY OPTIONS.

     Ameritech may either purchase transmission facilities (and any necessary
Cross-Connection) from Focal or provide its own transmission facilities and
terminate those transmission facilities in its equipment located in its
Collocation space at Focal's Premises.

     31.4 INTERCONNECTION POINTS AND CABLES.

     Focal shall:

     31.4.1 provide Ameritech an Interconnection point or points physically
accessible by both Ameritech and Focal, at which the fiber optic cable carrying
Ameritech's circuits can enter

______________

/20/  Total service access are access services purchased by Focal from Ameritech
 --                                                                            
      to provide switched or dedicated access to Focal Customers.

                                      97
<PAGE>
 
Focal's Premises; provided that Focal shall designate Interconnection Points as
                  --------
close as reasonably possible to Focal's Premises;

     31.4.2 provide at least two (2) such Interconnection points at Focal's
Premises at which there are at least two (2) entry points for Ameritech's cable
facilities, and at which space is available for new facilities in at least two
(2) of those entry points; and

     31.4.3 permit Ameritech Interconnection of copper or coaxial cable if such
Interconnection is first approved by the Commission.

     31.5   ALLOCATION OF COLLOCATION SPACE.

     31.5.1 Focal shall not be required to lease or construct additional space
in a Premises to provide Ameritech Physical Collocation when existing space in
such Premises has been exhausted.

     31.5.2 Ameritech will provide Focal a two (2)-year rolling forecast of its
requirements for Collocation that will be reviewed jointly on a yearly basis by
the Parties, in accordance with the planning processes agreed upon pursuant to
SCHEDULE 12.9.3. Focal will attempt to deliver Collocation pursuant to
- ---------------
Ameritech's forecasts to the extent that Collocation space is then available.

     31.5.3 The Parties expect that under normal conditions Focal will have
space available for Ameritech to interconnect with Focal for purposes of
terminating Local Traffic and IntraLATA Toll Traffic. However, should space not
be available, Focal will attempt to establish a POI at another mutually
agreeable Focal Wire Center which Focal determines has available space and
sufficient facilities for transporting, traffic between Focal Wire Centers at
rates, terms and conditions to be negotiated upon by the Parties. If an
alternative POI is not available in the LATA, the Parties will enter into good
faith negotiations to establish an alternative method for Ameritech to terminate
Local Traffic and IntraLATA Toll Traffic on Focal's network.

     31.6   SUBCONTRACTOR AND VENDOR APPROVAL. Focal shall allow Ameritech to
have an Focal-approved subcontractor install updates to Collocated equipment,
including software updates. Approval of such subcontractors by Focal shall be
based on the same criteria it uses in approving contractors for its own
purposes.

     31.7   DELIVERY OF COLLOCATED SPACE.

            31.7.1 Focal shall provide Ameritech with a single point of contact
for all inquiries regarding Collocation. If Ameritech needs to install
additional equipment in the LEC Access Equipment Room, Ameritech shall request
additional space for Collocation by delivering a written request to Focal. Each
request for Collocation shall include (i) the Premises in which Collocation is
requested, (ii) the interoffice transmission facilities Ameritech will require
for such space, (iii) the equipment to be housed in such space, and (iv) the
date on which Ameritech
<PAGE>
 
intends to initiate service from such space. Focal shall notify Ameritech in
writing within ten (10) Business Days of receiving Ameritech's request for
Collocation as to whether the requested space is available. If intraoffice
facilities will not be available for Collocation of initial service within three
(3) months after receipt of Ameritech's request for space pursuant to this
Section, then Focal shall provide written notification, within ten (10) Business
Days after the receipt of such request, as to when the intra office facilities
will be made available.

          31.7.2 Physical Collocation.

                 (a) If additional space for Physical Collocation is immediately
available at the time of Ameritech's request, Focal shall include in its notice
to Ameritech (i) the space to be provided and (ii) whether Focal can deliver the
space to Ameritech by the date set forth in SECTION 31.7.2(C).
                                            -----------------

                 (b) If Ameritech's requested Physical Collocation space is
available, Ameritech and Focal shall have an initial walkthrough of such
space within ten (10) Business Days after Focal confirms that the requested
space is available.

                 (c) Focal shall deliver to Ameritech the requested space on or
before the later of (i) one hundred twenty (120) days from Focal's receipt of
Ameritech's request for Collocation and (ii) such other reasonable date that the
Parties may agree upon if it is not feasible for Focal to deliver to Ameritech
such space within the foregoing intervals (such date of delivery referred to as
the "DELIVERY DATE").

                 (d) Physical Collocation will be subject to the additional
rules and regulations set forth in SCHEDULE 31.7.
                                   -------------

                 (e) After completion of construction, Focal and Ameritech will
complete an acceptance walkthrough of all Collocated space requested from Focal.
Exceptions that are noted during this acceptance walkthrough shall be corrected
by Focal within thirty (30) days after the walkthrough. Focal shall conduct a
root cause analysis of all exceptions identified. The correction of these
exceptions shall be at Focal's expense, subject to any change orders requested
by Ameritech.

                (f)  Ameritech shall also be entitled to credits for delays by
Focal in provisioning space for Collocation, and for the inability of Ameritech
to use equipment located in space provided for Collocation as a result of the
failure by Focal to comply with its obligations under this Agreement, pursuant
to terms and conditions agreed upon by the Implementation Team.

     31.8 PRICING. The prices charged to Ameritech for Collocation are set forth
on Exhibit PS-VII-A of the Pricing Schedule.

                                      99
<PAGE>
 
     31.9  BILLING.  Focal shall bill Ameritech for Collocation pursuant to the
requirements of ARTICLE XXVII to this Agreement.
                -------------

     31.10 ADDITIONAL REQUIREMENTS. The additional requirements set forth on
SCHEDULE 31.10 shall be applicable to Physical Collocation.
- ---------------                                            

     31.11 PROTECTION OF SERVICE AND PROPERTY.

           Both Parties shall exercise reasonable care to prevent harm or damage
to the other Party, its employees, agents or Customers, or their property. Both
Parties, their employees, agents, and representatives agree to take reasonable
and prudent steps to ensure the adequate protection of the other Party's
property and services, including:

           31.11.1  Ameritech and Focal shall restrict access to Ameritech
equipment, support equipment, systems, tools and data, or spaces which contain
or house Ameritech equipment enclosures, to Ameritech employees and other
authorized non-Ameritech personnel to the extent necessary to perform their
specific job function.
 
           31.11.2  Ameritech shall comply at all times with security and safety
procedures and existing requirements that are defined by Focal and communicated
to Ameritech.

           31.11.3  Focal shall allow Ameritech periodically to inspect or
observe spaces which house or contain Ameritech equipment or equipment
enclosures and furnish Ameritech with keys, entry codes, lock combinations, and
other materials or information which may be needed to gain entry into any
secured Ameritech space, subject to SECTION 31.11.2 and ARTICLE XX.
                                    ---------------     ----------

           31.11.4   Focal shall furnish to Ameritech a current written list of
Focal employees who Focal authorizes to enter Ameritech's Physical Collocation
space, with samples of the identifying credentials to be carried by such
persons.

           31.11.5  Focal shall secure external access to the Physical 
Collocation space on its Premises in the same or equivalent manner that Focal
secures external access to spaces that house Focal's equipment.

           31.11.6  Focal shall limit the keys used in its keying systems for
Ameritech's specific Physical Collocation space which contain or house Ameritech
equipment or equipment enclosures to its employees and representatives to
emergency access only. Ameritech shall further have the right, at its expense,
to have locks changed where deemed necessary for the protection and security of
such spaces, provided that Ameritech shall immediately provide Focal with such
             --------
new keys.

           31.11.7  Focal shall use its existig back-up and recovery plan in
accordance with its standard policies for the specific Wire Center.

                                      100
<PAGE>
 
      31.12 STANDARDS OF PERFORMANCE. Focal shall provide Collocation to
Ameritech in accordance with the service levels, procedures and intervals to be
agreed upon by the Implementation Team.

      IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
as of this 10th day of February 1999./21/
                                      --

FOCAL COMMUNICATIONS                       AMERITECH INFORMATION INDUSTRY
CORPORATION OF MICHIGAN                    SERVICES, A DIVISION OF AMERITECH
                                           SERVICES, INC., ON BEHALF OF AND AS
                                           AGENT FOR AMERITECH MICHIGAN


By: /s/ John R. Barnicle                   By: /s/ Karen S. Vessely
   --------------------------                 -----------------------------
Printed: John R. Barnicle                  Printed: Karen S. Vessely
        ---------------------                      ------------------------
Title:   C.O.O                             Title:   President
        ---------------------                      ------------------------

_____________________

/21/ This Agreement is the result of Focal's adoption of the terms and
 --
     conditions of that certain Interconnection Agreement under Sections 251 and
     252 of the Telecommunications Act of 1996 dated January 28, 1997 by and
     between Ameritech Michigan and Teligent, Inc. (the "Teligent Agreement").
     The Teligent Agreement was the result of Teligent's adoption of the terms
     and conditions of that certain Interconnection Agreement dated as of
     January 28, 1997 by and between Ameritech Michigan and AT&T Communications
     of Michigan, Inc. (the "AT&T Agreement"). This Agreement does not
     represent a voluntary or negotiated agreement under Section 252 of the
     Act but instead merely represents Ameritech's compliance with what Focal
     maintains is its rights under Section 252(i) of the Act. Filing and
     performance by Ameritech of this Agreement does not in any way constitute a
     waiver by Ameritech of its position of the illegality or unreasonableness
     of any rates, terms or conditions set forth in this Agreement, nor does it
     constitute a waiver by Ameritech of any rights and remedies it may have to
     seek review of this Agreement, the Teligent Agreement, or the AT&T
     Agreement, or to petition the Commission, other administrative body, or
     court for reconsideration or reversal of any determination made by the
     Commission in Cause No. U-11151/52 (the "AT&T Arbitration"), or seek 
     review in any way of any provisions included in this Agreement as a
     result of Focal's election under Section 252(i) of the Act. The Parties
     acknowledge that in no event shall any of the rates, terms or
     conditions set forth in this Agreement apply to any products or services
     purchased by Focal prior to the later of (i) the date the Commission
     approves this Agreement under Section 252(e) of the Act, and (ii) absent
     such Commission approval, the date this Agreement is deemed approved under
     Section 252(e)(4) of the Act.

     Neither Ameritech nor Focal's execution of this Agreement and compliance
     with the terms and conditions of this Agreement shall be construed as or is
     intended to be a concession or admission by either Party that any
     contractual provision required by the Commission in the AT&T Arbitration or
     any provision in this Agreement, the Teligent Agreement, or the AT&T
     Agreement complies with the rights and duties imposed by the Act, a
     decision by the FCC or the Commission, a decision of the courts, or other
     Applicable Law, and both Ameritech and Focal specifically reserve their
     respective full rights to assert and pursue claims arising from or related
     to this Agreement. Ameritech further contends that certain provisions of
     this Agreement including, without limitation. SECTIONS 9.1.2 and 9.2 are
                                                   --------------     ---       
     inconsistent with Ameritech's rights under the Act as interpreted by the
     United States Supreme Court in AT&T CORP. V. IOWA UTILITIES BD., 1999 WL
                                    --------------------------------
     24588 (Jan. 25, 1999). Ameritech reserves its rights, notwithstanding
     anything to the contrary in this Agreement, to exercise its rights as
     described in Footnote 9 of this Agreement, SECTION 29.3 of the Agreement,
                                                ------------
     and/or to seek appropriate legal and/or equitable relief. Further, in
     addition to any rights a Party may have under this Agreement including
     SECTION 29.3, if any provision in the AT&T Agreement is amended or modified
     ------------
     as result of any order or finding by the FCC, the Commission or a court of
     competent jurisdiction with respect to issues addressed in Case No. 97-
     60176 pending before the United States District Court of the Eastern
     District of Michigan (or any appeal thereof), this Agreement shall be
     deemed to be amended consistent with such order or finding, including the
     date such amendment is deemed effective.
<PAGE>
 
                                 SCHEDULE 1.2

                                  DEFINITIONS

     "9-1-1" means the services described in SECTION 3.9.
                                             ------------

     "9-1-1 CONTROL OFFICE SOFTWARE ENHANCEMENT CONNECTION CHARGE" is as
defined in SECTION 3.9.2(e) of this Agreement.
           ----------------

     "ACCESS TOLL CONNECTING TRUNKS" is as defined in SECTION 5.1.
                                                      -----------

     "ACT" means the Communications Act of 1934 (47 U.S.C. (S) 151 et seq.), as
                                                                   -------
amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission having authority to interpret the Act within its stsate of
jurisdiction.

     "ADSL" OR "ASYMMETRICAL DIGITAL SUBSCRIBER LINE" means a transmission
technology which transmits an asymmetrical digital signal using one of a variety
line of codes.

     "ADVANCED INTELLIGENT NETWORK" OR "AIN" is a network functionality that
permits specific conditions to be programmed into a switch which, when met,
directs the switch to suspend call processing and to receive special
instructions for further call handling instructions in order to enable carriers
to offer advanced features and services.

     "AFFILIATE" is As Defined in the Act.

     "AMA" means the Automated Message Accounting structure inherent in switch
technology that initially records telecommunication message information. AMA
format is contained in the Automated Message Accounting document, published by
Bellcore as GR-1100-CORE which defines the industry standard for message
recording.
          
     "APPLICABLE LAWS" is as defined in SECTION 19.2.
                                        -------------

     "ARBITRATOR" is the person selected by the Parties to serve as Arbitrator
for any dispute submitted to arbitration pursuant to the dispute resolution
process.

     "AS DEFINED IN THE ACT" means as specifically defined by the Act and as
from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     "AS DESCRIBED IN THE ACT" means as described in or required by the Act and
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     "AUTOMATIC LOCATION IDENTIFICATION" OR "ALI" means a feature by which the
service address associated with the calling party's listed telephone number
identified by ANI as defined

                                 Sch. 1.2 - 1
<PAGE>
 
herein, is forwarded to the PSAP for display. Additional telephones with the 
same number calling party's including secondary locations and off-premise 
extensions will be identified with the service address of the calling party's 
listed number.

     "AUTOMATIC NUMBER IDENTIFICATION" or "ANI" means a Feature Group D 
signaling parameter which refers to the number transmitted through a network 
identifying the billing number of a calling party. With respect to 9 1 1 and E9
1 1, "ANI" means a feature by which the calling party's telephone number is 
automatically forwarded to the E9-1-1 Control Office and to the PSAP display and
transfer office

     "AUTOMATIC ROUTE SELECTION" or "ARS" means a service feature associated 
with a specific grouping of lines that provides for automatic selection of the 
least expensive or most appropriate transmission facility for each call based on
criteria programmed into the system.

     "BELLCORE" means Bell Communications Research, Inc.

     "BILL DATE" means the date that a bill is issues by a party.

     "BINDING FORECAST" is as defined in SECTION 19.5.3.
                                         --------------   

     "BLV/BLVI TRAFFIC" means an operator service call in which the caller 
inquires as to the busy status of or requests an interruption of a call on 
another Customer's Telephone Exchange Service line.

     "BUSINESS DAY" means a day on which banking institutions are required to be
open for business in Chicago, Illinois.

     "BONA FIDE REQUEST" means the process described on SCHEDULE 2.2.
                                                        ------------ 

     "CABS" means the Carrier Access Billing System which is contained in a 
document prepared under the direction of the Billing Committee of the OBF. The 
Carrier Access Billing System document is published by Bellcore in Volumes 1, 
1A, 2, 3, 3A, 4 and 5 as Special Reports SR-OPT-001868, SR-OPT-001869, 
SR-OPT-001871, SR-OPT-001872, SR-OPT-001873, SR-OPT-001874, and SR-OPT-001875,
respectively, contains the recommended guidelines for the billing of access and
other connectivity services.

     "CALLING PARTY NUMBER" or "CPN" is a Common Channel Interoffice Signaling 
("CCIS") parameter which refers to the number transmitted through a network 
identifying the calling party.

     "CARRIER OF RECORD" is as defined in SECTION 10.11.3.
                                          ---------------

     "CCS" means one hundred (100) call seconds.

                                 Sch. 1.2 - 2
<PAGE>
 
     "CENTRAL OFFICE SWITCH" means a switch used to provide Telecommunications
Services, including:

          (a)  "END OFFICE SWITCHES," which are used to terminate Customer
     station Loops for the purpose of Interconnection to each other and to
     trunks; and

          (b) "TANDEM OFFICE SWITCHES," OR "TANDEMS," which are used to connect
               and switch trunk circuits between and among other Central Office
               Switches.
               
     A Central Office Switch may also be employed as a combination End Office/
Tandem Office Switch.

     "CENTREX" means a Telecommunications Service associated with a specific
grouping of lines that uses Central Office switching equipment for call routing
to handle direct dialing of calls and to provide many private branch 
exchange-like features.

     "CLASS FEATURES" means certain CCIS-based features available to Customers
including: Automatic Call Back; Caller Identification and related blocking
features; Distinctive Ringing/Call Waiting; Selective Call Forward; and
Selective Call Rejection.

     "COMMERCIAL MOBILE RADIO SERVICE"' OR "CMRS" is As Defined in the Act.

     "COBO" is as defined in SECTION 12.12.2(b).
                             ------------------

     "COLLOCATION" is As Described in the Act.

     "COMBINATION" is as defined in SECTION 9.3.1.
                                    -------------

     "COMMISSION" or "MPSC" means the Michigan Public Services Commission.

     "COMMON CHANNEL INTEROFFICE SIGNALING" OR "CCIS" means the signaling
system, developed for use between switching systems with stored-program
control, in which all of the signaling information for one or more groups of
trunks is transmitted over a dedicated high-speed data link rather than on a
per-trunk basis and, unless otherwise agreed by the Parties, the CCIS used by
the Parties shall be SS7.

     "CONSEQUENTIAL DAMAGES" is as defined in SECTION 26.5.
                                              ------------

     "CONTRACT MONTH" means a calendar month (or portion thereof) during the
term of this Agreement. Contract Month 1 shall commence on the first day of
the first calendar month following the Effective Date and end on the last day of
that calendar month.

     "CONTRACT YEAR" means a twelve (12)-month period during the term of this
Agreement commencing on the Effective Date and each anniversary thereof

                              Sch. 1. 2 - 3
<PAGE>
 
     "CONTROL OFFICE" means the Central Office providing Tandem Switching
Capability for E9-1-1 calls. The Control Office controls switching of ANI 
information to the PSAP and also provides the Selective Routing feature,
standard speed calling features, call transfer capability and certain
maintenance functions for each PSAP.

      "CROSS CONNECTION" means a connection provided pursuant to Collocation at
the Digital Signal Cross Connect, Main Distribution Frame or other suitable
frame or panel between (i) the collocated Party's equipment and (ii) the
equipment of a third-party collocated Telecommunications Carrier or the
equipment or facilities of the other Party which provides such Collocation.

     "CUSTOMER" means a third-party residence or business that subscribes to
Telecommunications Services provided at retail by either of the Parties.

     "CUSTOMER LISTING(S)" means a list containing the names, the telephone
numbers, addresses and zip codes of Customers within a defined geographical
area, except to the extent such Customers have requested not to be listed in a
directory.

     "CUSTOMER NAME AND ADDRESS INFORMATION" or "CNA" means the name, service
address and telephone numbers of a Party's Customers for a particular Exchange
Area. CNA includes nonpublished listings, coin telephone information and
published listings.

     "CUSTOMER PROPRIETARY NETWORK INFORMATION" is As Defined in the Act.

     "CUSTOMER USAGE DATA" is as defined in SECTION 10.16.1.
                                            ---------------

     "DATA MANAGEMENT SYSTEM" or "DMS" means a system of manual procedures
and computer processes used to create, store and update the data required to
provide the Selective Routing ("SR") and ALI features.

     "DELAYING EVENT" means (a) any failure of a Party to perform any of its
obligations set forth in this Agreement, caused in whole or in part by (i) the
failure of the other Party to perform any of its obligations set forth in this
Agreement (including the Implementation Schedule and the Implementation Plan),
or (ii) any delay, act or failure to act by the other Party or its Customer,
agent or subcontractor or (b) any Force Majeure Event.

     "DELIVERY DATE" is as defined in SECTIONS 12.12.2(b) and 12.12.3(b).
                                      -------------------     ----------

     "DERIVATIVE INFORMATION" is as defined in SECTION 20.1.1(b).
                                               -----------------

     "DIALING PARTY" is As Defined in the Act.
           
     "DIGITAL SIGNAL LEVEL" means one of several transmission rates in the time-
division multiplex hierarchy.

                                 Sch. 1.2 - 4
<PAGE>
 
     "DIGITAL SIGNAL LEVEL 0" OR "DS0" means the 64 Kbps zero-level signal in
the time-division multiplex hierarchy.

     "DIGITAL SIGNAL LEVEL 1" OR "DS1" means the 1.544 Mbps first-level signal
in the time-division multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS1 is the initial level of multiplexing.

     "DIGITAL SIGNAL LEVEL 3" OR "DS3" means the 44.736 Mbps third-level in the
time-division multiplex hierarchy. In the time-division multiplexing hierarchy
of the telephone network, DS3 defined as the third level of multiplexing.

     "DISCLOSING PARTY" is as defined in SECTION 20.1.1.
                                         --------------

     "DISPUTE" is as defined in SECTION 28.3.
                                ------------

     "DISPUTED AMOUNTS" is as defined in SECTION 28.2.1.
                                         --------------

     "DOCUMENTATION OF AUTHORIZATION" is as defined in SCHEDULE 10.11.1.
                                                       ----------------

     "EFFECTIVE DATE" is the date indicated in the Preamble on wh1ch this
Agreement shall become effective.

     "EMERGENCY SERVICES" mean police, fire, ambulance, rescue and medical
services.

     "E9-1-1" or "ENHANCED 9-1-1 (E9-1-1) SERVICE" provides completion of 9-1-
1 calls via dedicated trunking facilities and includes Automatic Number
Identification (ANI), Automatic Location Identification (ALI) and/or Selective
Routing (SR).

     "EQUAL IN QUALITY" is as defined in SECTION 3.6.
                                         -----------

     "EXCHANGE ACCESS" is As Defined in the Act.

     "EXCHANGE AREA" means an area, defined by the Commission, for which a
distinct local rate schedule is in effect.

     "EXCHANGE MESSAGE RECORD" or "EMR" means the standard used for exchange
of Telecommunications message information among Telecommunications providers for
billable, non-billable, sample, settlement and study data. EMR format is
contained in Bellcore Practice BR-010-200-010 CRIS Exchange Message Record.

     "FCC" means the Federal Communications Commission.

     "FIBER-MEET" means an Interconnection architecture method whereby the
Parties physically Interconnect their networks via an optical fiber interface
(as opposed to an electrical interface) at

                                 Sch. 1.2 - 5
<PAGE>
 
a mutually agreed upon location, at which one Party's responsibility or
service begins and the other Party's responsibility ends.

     "FORCE MAJEURE EVENT" is as defined in SECTION 30.5.
                                            ------------

     "FORECAST PROVIDER" is as defined in SECTION 19.5.3.
                                          --------------

     "GRANDFATHERED SERVICES" is as defined in SECTION 10.3.1.
                                               --------------

     "HAZARDOUS SUBSTANCES" is as defined in SECTION 19.4.
                                             ------------

     "HDSL" or "HIGH-BIT RATE DIGITAL SUBSCRIBER LINE" means a transmission
technology which transmits up to a DS1-level signal, using any one of the
following line codes: 2 Binary/ 1 Quartenary ("2BIQ"), Carrierless AM/PM,
Discreet Multitone ("DMT"), or 3 Binary / 1 Octel ("3B10").

     "IMPLEMENTATION PLAN" is as defined in SECTION 18.2.
                                            ------------

     "IMPLEMENTATION TEAM" is as defined in SECTION 18.1.
                                            ------------

     "INCUMBENT LOCAL EXCHANGE CARRIER" OR "ILEC" is As Defined in the Act.

     "INFORMATION SERVICE TRAFFIC" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which
is addressed to an information service provided over a Party's information
services platform (e.g., 976).

     "INITIAL BILLING COMPANY" OR "IBC" means the Local Exchange Carrier which
provides the Feature Group B or D services in an End Office. For purposes of
this Agreement, Focal is the IBC.

     "INITIAL TERM" is as defined in SECTION 21.1.
                                     ------------

     "INSUFFICIENT CAPACITY" is as defined in SECTION 16.1.2.
                                              --------------

     "INTEGRATED DIGITAL LOOP CARRIER" means a subscriber loop carrier system
that is twenty-four (24) local Loop transmission paths combined into a 1.544
Mbps digital signal which integrates within the switch at a DS1 level.

     "INTEGRATED SERVICES DIGITAL NETWORK" OR "ISDN" means a switched network
service that provides end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN (BRI-ISDN) provides
for a digital transmission of two 64 Kbps bearer channels and one 16 Kbps data
channel (2B+D).

     "INTELLECTUAL PROPERTY" means copyrights, patents, trademarks, trade-
secrets, mask works and all other intellectual property rights.
                                                      
                                 Sch. 1.2 - 6
<PAGE>
 
     "INTERCONNECTION" is As Defined in the Act.

     "INTERCONNECTION ACTIVATION DATE" is as defined in SECTION 2.1.
                                                        -----------

     "INTEREXCHANGE CARRIER" or "IXC" means a carrier that provides interLATA or
intraLATA Telephone Toll Services.

     "INTERIM TELECOMMUNICATIONS NUMBER PORTABILITY" OR "INP" is as described
in the Act.

     "INTERLATA" is As Defined in the Act.

     "INTRALATA TOLL TRAFFIC" means all intraLATA calls other than Local Traffic
calls but including interzone calls.

     "LISTING UPDATE(S)" means information with respect to Customers necessary
for Publisher to publish directories under this Agreement in a form and format
acceptable to Publisher. For Customers whose telephone service has changed since
the last furnished Listing Update because of new installation, disconnection,
change in address, change in name, change in non-listed or non-published status,
or other change may affect the listing of the Customer in a directory, Listing
Updates shall also include information necessary in order for Publisher to
undertake initial delivery and subsequent delivery of directories, including
mailing addresses, delivery addresses and quantities of directories requested by
a Customer. In the case of Customers who have transferred service from another
LEC to Focal without change of address, Listing Updates shall also include the
Customer's former listed telephone number and former LEC, if available.
Similarly, in the case of Customers who have transferred service from Focal to
another LEC, Listing Updates shall also include the Customer's referral
telephone number and new LEC, if available.

     "LINE INFORMATION DATABASE(S) (LIDB)" means one or all, as the context may
require, of the Line Information Databases owned individually by ILECs and other
entities which provide, among other things, calling card validation
functionality for telephone line number cards issued by ILECs and other
entities. A LIDB also contains validation data for collect and third number-
billed calls, which include billed number screening.

     "LOCAL ACCESS AND TRANSPORT AREA" or "LATA" is As Defined in the Act.

     "LOCAL EXCHANGE CARRIER" or "LEC" is As Defined in the Act.

     "LOCAL LOOP TRANSMISSION" or "LOOP" means the transmission path which
extends from Network Interface Device or demarcation point at a Customer's
premises to the Main Distribution Frame or other designated frame or panel in
a Party's Wire Center which services the Customer. Loops are defined by the
electrical interface rather than the type of facility used.

                                 Sch. 1.2 - 7
<PAGE>
 
     "LOCAL NUMBER PORTABILITY" OR "LNP" means the ability of users of
Telecommunications Services to retain, at the same location, existing telephone
numbers without impairment of quality, reliability, or convenience when
switching from one Telecommunications Carrier to another.

     "LOCAL TRAFFIC" means those calls as defined by Ameritech's local calling
area as described in maps, tariffs, or rule schedules filed with and approved by
the Commission as of the Effective Date.

     "LOSS" or "LOSSES" means any and all losses, costs (including court
costs), claims, damages (including fines, penalties, and  criminal or civil
judgments and settlements), injuries, liabilities and expenses (including
attorneys' fees).

     "MAIN DISTRIBUTION FRAME" means the distribution frame of the Party
providing the Loop used to interconnect cable pairs and line and trunk equipment
terminals on a switching system.

     "MAKE-READY WORK" means all work, including rearrangement or transfer
of existing facilities or other changes required to accommodate Focal's
Attachments.

     "MECAB" refers to the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
(OBF), which functions under the auspices of the Carrier Liaison Committee
(CLC) of the Alliance for Telecommunications Industry Solutions (ATIS). The
MECAB document published by Bellcore as Special Report SR-BDS-000983 contains
the recommended guidelines for the billing of an access service provided by
two or more LECs, or by one LEC in two or more states within a single LATA.

     "MEET-POINT BILLING" means the process whereby each Party bills the
appropriate tariffed rate for its portion of a jointly provided Switched
Exchange Access Service.

     "MULTIPLE BILL/SINGLE TARIFF" means that each Party will prepare and
render its own meet point bill in accordance with its own tariff for its portion
of the switched access service.

     "NETWORK ELEMENT" is As Defined in the Act.

     "NORTH AMERICAN NUMBERING PLAN" or "NANP" means the numbering plan used in
the United States that also serves Canada, Bermuda, Puerto Pico and certain
Caribbean Islands. The NANP format is a 10-digit number that consists of a 3-
digit NPA code (commonly referred to as the area code), followed by a 3-digit
NXX code and 4-digit line number.

     "NUMBER PORTABILITY" is As Defined in the Act.

     "NXX" means the three-digit code which appears as the first three digits
of a seven-digit telephone number.

                                 Sch. 1.2 - 8
<PAGE>
 
      "OBF" means the Ordering and Billing Forum (OBF), which functions under
the auspices of the Carrier Liaison Committee (CLC) of the Alliance for
Telecommunications Industry Solutions (ATIS).

     "OCCUPANCY DATE" is as defined in SECTION 12.12.2(E).
                                       ------------------

     "OPTICAL LINE TERMINATING MULTIPLEXOR" or "OLTM" is as defined in
SECTION 3.3.
- -----------

     "PARTY" means either Ameritech or Focal, and "PARTIES" means Ameritech and
Focal.

     "PHYSICAL COLLOCATION" is As Defined in the Act.

     "PIC" is as defined in SECTION 10.11.4.
                            ---------------

     "PLAN" is as defined in SECTION 8.1.
                             -----------

     "PREMISES" is As Defined in the Act.

     "PRIMARY LISTING" means the single directory listing provided to Customers
by Publisher under the terms of this Agreement. Each telephone configuration
that allows a terminating call to hunt for an available time among a series of
lines shall be considered a single Customer entitled to a single primary
listing.

     "PROPRIETARY INFORMATION" is as defined in SECTION 20.1.1.
                                                 --------------

     "PUBLIC SAFETY ANSWERING POINT" or "PSAP" means an answering location for
9-1-1 calls originating in a given area. A PSAP may be designed as Primary or
Secondary, which refers to the order in which calls are directed for answering.
Primary PSAPs respond first; Secondary PSAPs receive calls on a transfer basis
only, and generally serve as a centralized answering location for a particular
type of emergency call. PSAPs are staffed by employees of Service Agencies such
as police, fire or emergency medical agencies or by employees of a common bureau
serving a group of such entities.

     "PUBLISHER" means Ameritech's White Pages Directories publisher.

     "RATE CENTER" means the specific geographic point which has been designated
by a given LEC as being associated with a particular NPA-NXX code which has been
assigned to the LEC for its provision of Telephone Exchange Service. The Rate
Center is the finite geographic point identified by a specific V&H coordinate,
which is used by that LEC to measure, for billing purposes, distance sensitive
transmission services associated with the specific Rate Center; provided that a
                                                                --------
Rate Center cannot exceed the boundaries of an Exchange Area as defined by the
Commission.

     "RECEIVING PARTY" is as defined in SECTION 20.1.1.
                                        --------------

                                 Sch. 1.2 - 9
<PAGE>
 
      "RECIPROCAL COMPENSATION" is As Described in the Act.

      "REFERRAL ANNOUNCEMENT" is as defined in ARTICLE XVII.
                                               ------------

      "RENEWAL TERM" is as defined in SECTION 21.1
                                      ------------

      "RESALE LISTING(S)" means a list containing the names, the telephone
numbers, addresses and zip codes of Customers of Focal within the defined
geographic area, except to the extent such Customers of Focal have requested
not to be listed in a directory.

      "RESALE SERVICES" is as defined in SECTION 10.1.
                                         ------------

      "RESALE TARIFF" is as defined in SECTION 10.11.2.
                                       ---------------

      "ROUTING POINT" means a location which a LEC has designated on its own
network as the homing (routing) point for inbound traffic to one or more of its
NPA-NXX codes. The Routing Point is also used to calculate mileage measurements
for the distance-sensitive transport element charges of Switched Exchange Access
Services. Pursuant to Bellcore Practice BR 795-100-100 (the "RP PRACTICE"), the
Routing Point (referred to as the "RATING POINT" in such RP Practice) may be an
End Office Switch location, or a "LEC CONSORTIUM POINT OF INTERCONNECTION".
Pursuant to such RP Practice, each "LEC CONSORTIUM POINT OF INTERCONNECTION"
shall be designated by a common language location identifier (CLLI) code with
(x)KD in positions 9, 10, 11, where (x) may be any alphanumeric A-Z or 0-9. The
Routing Point must be located within the LATA in which the corresponding NPA-NXX
is located. However, Routing Points associated with each NPA-NXX need not be the
same as the corresponding Rate Center, nor must there be a unique and separate
Routing Point corresponding to each unique and separate Rate Center; provided
                                                                     --------
only that the Routing Point associated with a given NPA-NXX must be located in
the same LATA as the Rate Center associated with the NPA-NXX.

      "SELECTIVE ROUTING" OR "SR" means an E9-1-1 feature that routes an E9-1-1
call from a Control Office to the designated Primary PSAP based upon the
identified number of the calling party.

      "SERVICE AGENCY" means the public agency, the State or any local
government unit or special purpose district which has the authority to provide
police, fire fighting, medical or other emergency services, which has requested
the local telephone company to provide an E9-1-1 Telecommunications Service for
the purpose of voice-reporting emergencies by the public.

      "SERVICE CONTROL POINT" OR "SCP" is As Defined in the Act.

      "SERVICE LINE" means a telecommunications link from the Central Office
terminating at the PSAP.

                                 Sch. 1.2 - 10
<PAGE>
 
      "SIGNALING END POINT" OR "SEP" means a signaling point, other than an STP,
which serves as a source or a repository for CCIS messages.

      "SIGNAL TRANSFER POINT" OR "STP" is As Defined in the Act.

      "SUBSEQUENT BILLING COMPANY" OR "SBC" means the Local Exchange Carrier
which provides a segment of transport or switching services in connection with
Feature Group B or D switched access service. For purposes of this Agreement,
Ameritech is initially the SBC.

      "SUNSETTED SERVICES" is as defined in SECTION 10.3.2.
                                            --------------

      "SWITCHED ACCESS DETAIL USAGE DATA" means a category 1101XX record as
defined in the EMR Bellcore Practice BR 010-200-010.

      "SWITCHED ACCESS SUMMARY USAGE DATA" means a category 1150XX record as
defined in the EMR Bellcore Practice BR 010-200-010.

      "SWITCHED EXCHANGE ACCESS SERVICE" means the offering of transmission or
switching services to Telecommunications Carriers for the purpose of the
origination or termination of Telephone Toll Service. Switched Exchange Access
Services include: Feature Group A, Feature Group B, Feature Group D, 800/888
access, and 900 access and their successors or similar Switched Exchange Access
Services.

      "SYNCHRONOUS OPTICAL NETWORK" or "SONET" means an optical interface
standard that allows inter-networking of transmission products from multiple
vendors. The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are direct
multiples of the base rate, up to 13.22 Gpbs.

      "TECHNICAL REFERENCE SCHEDULE" is the list of technical references set
forth in SCHEDULE 2.3.
         ------------

      "TECHNICALLY FEASIBLE POINT" is As Described in the Act.

      "TELECOMMUNICATIONS" is As Defined in the Act.

      "TELECOMMUNICATIONS ACT" means the Telecommunications Act of 1996 and any
rules and regulations promulgated thereunder.
 
      "TELECOMMUNICATIONS ASSISTANCE PROGRAM" means any means-tested or
subsidized Telecommunications Service offering, including Lifeline, that is
offered only to a specific category of subscribers.

      "TELECOMMUNICATIONS CARRIER" is As Defined in the Act.

      "TELECOMMUNICATIONS SERVICE" is As Defined in the Act.

                                 Sch. 1.2 - 11
<PAGE>
 
     "TELEPHONE EXCHANGE SERVICE" is As Defined in the Act.

     "TELEPHONE RELAY SERVICE" means a service provided to speech and hearing-
impaired callers that enables such callers to type a message into a telephone
set equipped with a keypad and message screen and to have a live operator read
the message to a recipient and to type message recipient's response to the
speech or hearing-impaired caller.

      "TELEPHONE TOLL SERVICE" is As Defined in the Act.

      "FOCAL DIRECTORY CUSTOMER" is as defined in SECTION 15.1.
                                                  ------------

      "UNAUTHORIZED SWITCHING" is as defined in SECTION 10.11.2(a).
                                                ------------------

      "VIRTUAL COLLOCATION" is As Defined in the Act.

      "WHITE PAGES DIRECTORIES" means directories or the portion of co-bound
directories which include a list in alphabetical order by name of the telephone
numbers and addresses of telecommunication company customers.

     "WHOLESALE RESALE SERVICES" is as defined in SECTION 10.1.
                                                  ------------

     "WIRE CENTER" means the Premises of a Party which serves as a Routing Point
for Switched Exchange Access Service.

                                 Sch. 1.2 - 12
                                         
<PAGE>
 
                                  SCHEDULE 2.1
                           IMPLEMENTATION SCHEDULE
                                   Michigan

                                
<TABLE> 
<CAPTION>                      
  LATA    LEC Office CLLI        Focal             Ameritech     Interconnection
                             Interconnection    Interconnection  Activation Date
                              Wire Center         Wire Center  
                                 FIWC               (AIWC)      
<S>     <C>                <C>                 <C>              <C>
        Tandems

340     DTRTMIBH20T        DTRTMIMDH02         SFLDMIMKDSO      See Note 1

340     PNTCMIM50T         PNTCMIMNH15         SFLDMIMKDSO      "

340     WAYNMIMN20T        WAYNMIMMNH00        SFLDMIMKDSO      "

340     WBFDMIMN20T        SFLDMIMNH13         SFLDMIMKDSO      "           
 

        End Offices

340     ABHGMIMNDSO        ABHGMIMNHOO         SFLDMIMKDSO      See Note 1

340     ANARMIMNDSO        WAYNMIMNHOO         SFLDMIMKDSO      "

340     BITNMIESDSO        NRVLMIMNHOO         SFLDMIMKDSO      "

340     BRHMMIMNDSO        BRHMMIMNHOO         SFLDMIMKDSO      "           

340     CKTNMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     CMRCMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     CNLNMIMNDSO        CNLNMIMNHOI         SFLDMIMKDSO      "

340     DTRTMIVWDSO        DTRTMIBLH23         SFLDMIMKDSO      "

340     DRBRMIDBDSO        DRBRMIFBHO7         SFLDMIMKDSO      "

340     DRBRMIFBDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRBRMIFBDSI        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRBRMIORDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRPLMIDPDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     FLNTMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     FLRKMIFRDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     HGPKMITSDSO        DTRTMIMDH02         SFLDMIMKDSO      "

340     HOWLMIMNDSO        NRVLMIMNH00         SFLDMIMKDSO      "
</TABLE>                                       
                                               
                                 Sch. 2.1 - 1
<PAGE>
 
<TABLE> 
<CAPTION>                      
  LATA    LEC Office CLLI        Focal             Ameritech     Interconnection
                             Interconnection    Interconnection  Activation Date
                              Wire Center         Wire Center  
                                 FIWC               (AIWC)      
<S>     <C>                <C>              <C>                 <C>
340     LIVNMIMNDSO        LIVNMIMNH01      SFLDMIMKDSO         " 

340     LNPKMIATDSO        DRBRMIFBHO7      SFLDMIMKDSO         " 

340     MTCLMICLDSO        TROYMISMH06      SFLDMIMKDSO         " 

340     MTCLMIMNDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     MTCLMINRDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     PLMOMIMNDSO        PLMOMIMNH00      SFLDMIMKDSO         " 

340     PTHRMIMNDSO        PNTCMIMNH15      SFLDMIMKDSO         " 

340     RMLSMIMNDSO        WAYNMIMNH00      SFLDMIMKDSO         " 

340     ROCHMIMNDSO        PNTCMIMNH15      SFLDMIMKDSO         " 

340     RSVLMIMNDSO        CNLNMIMNH01      SFLDMIMKDSO         " 

340     RYLOMIMNDSO        RYLOMIMNH02      SFLDMIMKDSO         " 

340     SFLDMIMNDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     SFLDMIMNDS1        SFLDMIMNH13      SFLDMIMKDSO         " 

340     SFLDMIOKDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     TAYLMIWKDSO        DRBPMIFBH07      SFLDMIMKDSO         " 

340     TRENMIMNDSO        DRBRMIFBH07      SFLDMIMKDSO         " 

340     TROYMIMNDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     TROYMISMDSO        TROYMISMH06      SFLDMIMKDSO         " 

340     UTICMIMNDSO        ABHGMIMNH00      SFLDMIMKDSO         " 

340     WBFDMIMNDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     WKLKMIMNDSO        NRVLMIMNH00      SFLDMIMKDSO         " 

340     WRRNMIMNDSO        WRRNMIMNH01      SFLDMIMKDSO         " 

340     WRRNMITLDSO        WRRNMITLH00      SFLDMIMKDSO         " 

340     YPSLMIMNDSO        WAYNMIMNH00      SFLDMIMKDSO         " 
</TABLE> 

Note I - Interconnection Activation Date is 150 days from the execution date on
the signature block.

                                 Sch. 2.1 - 2
<PAGE>
 
                                  SCHEDULE 2.2

                               BONA FIDE REQUEST

      1.  Ameritech shall promptly consider and analyze the submission of a
Bona Fide Request that Ameritech provide: (a) Interconnection, access to an
unbundled Network Element (including Combinations thereof) not otherwise
provided hereunder at the time of such request; (b) an Interconnection or
connection to a Network Element that is different in quality to that which
Ameritech provides itself at the time of such request; or (c) a customized
service for features, capabilities, functionalities or unbundled Network Element
not otherwise provided hereunder at the time of such request.

      2.  A Bona Fide Request shall be submitted in writing and shall include a
technical description of each requested Interconnection, Network Element,
Combination and/or customized feature, capability or functionality.

      3.  Focal may cancel a Bona Fide Request at any time, but shall pay
Ameritech's reasonable and demonstrable costs of processing and/or implementing 
the Bona Fide Request up to the date of cancellation, except if (i) any 
processing charges are of the type which are not generally passed on by 
Ameritech to its retail or resale Customers and (ii) such costs or cost 
categories representing such charges are not included in the prices Focal pays 
for the services provided by Ameritech under this Agreement.

      4.  Within five (5) Business Days of its receipt, Ameritech shall
acknowledge receipt of the Bona Fide Request.

      5.  Within thirty (30) days of its receipt of a Bona Fide Request,
Ameritech shall provide to Focal a preliminary, analysis of such
Interconnection, Network Element, or requested level of quality thereof that is
the subject of the Bona Fide Request or customized feature, capability or
functionality. The preliminary analysis shall confirm that Ameritech will either
offer access to the Interconnection, Network Element, or requested level of
quality or will provide a detailed explanation that access to such
Interconnection, Network Element, or requested level of quality is not
technically feasible and/or that the request does not qualify as an
Interconnection, Network Element, or requested level of quality that is required
to be provided under the Act. If the receiving Party determines that the
Interconnection, Network Element, or requested level of quality that is the
subject of the Bona Fide Request is technically feasible and is otherwise
required to be provided under the Act, Ameritech shall provide Focal a firm
price proposed and availability date for such development ("BONA FIDE REQUEST
QUOTE"). For Bona Fide Requests that involve either: (i) combinations of
standard offerings or (ii) individual customer arrangements that do not require
alterations not otherwise performed for individual customer arrangements, for
Ameritech retail customers, Ameritech shall provide a Bona Fide Request Quote
within such thirty (30)-day period. For all other Bona Fide Requests, Ameritech
shall provide a Bona Fide Request Quote as soon as feasible, but in any event
not more than sixty (60) days from the date Ameritech received such Bona Fide
Request. 

      6.  Within thirty (30) days of  receipt of the Bona Fide Request Quote, 
the requesting Party must either confirm its order for such Interconnection or 
Network Element pursuant to the Bona Fide Request Quote or, if it believes such 
quote is inconsistent with the requirements of the Act, exercise its rights 
under SECTION 28.3.
      ------------

      7.  Unless Focal agrees otherwise, all prices shall be consistent with
 the pricing principles of the Act, FCC and/or the Commission.

      8.  If a Party to a Bona Fide Request believes that the other Party
is not requesting, negotiating,or processing the Bona Fide Request in good
faith, or disputes a determination, or price or cost quote, such Party may
exercise its rights under SECTION 28.3.
                          ------------

                                 Sch. 2.2 - 1
<PAGE>
 
                                 SCHEDULE 2.3

                         TECHNICAL REFERENCE SCHEDULE

 Unbundled Network Elements
 --------------------------

      Unbundled Loop Transmission
      ---------------------------

      Bellcore TA-NWT-000393
      ANSI T1.413-1995 Specifications
      AM TR-TMO-000122
      AM TR-TMO-000123
      Bellcore TR-NWT-000393
      ANSI T1. 102-1993, American National Standard for Telecommunication -
          Digital Hierarchy - Electrical Interfaces
      Bellcore Technical Requirement TR-NWT-000499, Issue 5, December 1993,
          section 7
      ANSI T1.413-1995
      ANSI TIE 1 Committee Technical report Number 28

      Local Switching
      ---------------

      Bellcore FR-NWT-000064 (Local Switching Systems General Requirements)
      Bellcore GR-1432-CORE (TCAP)
      Bellcore GR-905-CORE (ISUP)
      Bellcore GR-1429-CORE (Call Management)
      Bellcore GR-1357-CORE (Switched Fractional DS1)
      Bellcore GR-1428-CORE (Toll Free Service)
      Bellcore GR-1597-CORE (Calling Name)
      Bellcore GR-954-CORE (Line Information Database)
      Bellcore GR-2863-CORE (Advanced Intelligent Network)
      GR-1298-CORE, AIN Switching System Generic Requirements
      GR-1299-CORE, AIN Switch-Service Control Point (SCP)/Adjunct Interface
          Generic Requirements
      TR-NWT-001284, AIN 0.1 Switching System Generic Requirements
      SR-NWT-002247, AIN Release 1 Update
      ANSI standards Q.931, Q.932
      Bellcore TR-NWT-08
      Bellcore TR-NWT-303
      TR-NWT-000393, January 1991, Generic Requirements for ISDN Basic Access
          Digital Subscriber Lines
      Bellcore TR-NWT-303

                                 Sch. 2.3 - 1
<PAGE>
 
      Dedicated and Shared Transport
      ------------------------------

      AM TR-NIS-000111
      AM RT-NIS 000133
      ANSI T1.101-1994, American National Standard for Telecommunications -
           Synchronization Interface Standard Performance and Availability
      ANSI T1.102-1993 American National Standard for Telecommunications -
          Digital Hierarchy - Electrical Interfaces
      ANSI T1.105-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Basic Description including
           Multiplex Structure, Rates and Formats
      ANSI T1.105.01-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Automatic Protection Switching
      ANSI T1.105.02-1995, American National Standard for Telecommunications
           - Synchronous Optical Network (SONET) - Payload Mappings
      ANSI T1.105.03-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Jitter at Network Interfaces
      ANSI T1.105.03a-1995, American National Standard for Telecommunications
           - Synchronous Optical Network (SONET)- Jitter at Network Interfaces
           - DS1 Supplement
      ANSI T1.105.04-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Data Communication Channel
           Protocols and Architectures
      ANSI T1.105.05-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Tandem Connection
      ANSI T1.106-1988, American National Standard for Telecommunications -
           Digital Hierarchy - Optical Interface Specifications (Single Mode)
      ANSI T 1.107-1988, American National Standard for Telecommunications -
           Digital Hierarchy - Formats Specifications
      ANSI T 1.107a-1990, American National Standard for Telecommunications -
           Digital Hierarchy - Supplement to Formats Specifications (DS3 Format
           Applications)
      ANSI T1.107b-1991, American National Standard for Telecommunications
           Digital Hierarchy - Supplement to Formats Specifications
      ANSI T1.117-1991, American National Standard for Telecommunications
           Digital Hierarchy - Optical Interface Specifications (SONET) (Single
           Mode - Short Reach)
      ANSI T1.119-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications
      ANSI T1.119.01-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications Protection
           Switching Fragment 
      ANSI T1.119.02-199x, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications Performance
           Monitoring Fragment

                                 Sch. 2.3 - 2
<PAGE>
 
      ANSI T1.231-1993, American National Standard for Telecommunications -
           Digital Hierarchy - Layer 1 In-Service Digital Transmission
           performance monitoring
      ANSI T1.403-1989, Carrier to Customer Installation, DS1 Metallic Interface
           Specification
      ANSI T1.404-1994, Network-to-Customer Installation - DS3 Metallic
           Interface Specification
      Bellcore FR-440 and TR-NWT-000499, Transport Systems Generic Requirements
           (TSGR): Common Requirements
      Bellcore GR-820-CORE, Generic Transmission Surveillance: DS1 & DS3
           Performance
      Bellcore GR-253-CORE, Synchronous Optical Network Systems (SONET); Common
           Generic Criteria
      Bellcore TR-NWT 000507, Transmission, Section 7, Issue 5 (Bellcore,
           December 1993). (A module of LSSGR, FR-NWT-000064.)
      Bellcore TR-NWT-000776, Network Interface Description for ISDN Customer
           Access
      Bellcore TR-INS-000342, High-Capacity Digital Special Access Service-
           Transmission Parameter Limits and Interface Combinations, Issue 1,
           February 1991

      Signaling Transfer Points (STPs)
      --------------------------------

      ANSI T1.111.2 
      ANSI T1.111.3
      ANSI T1.111.4
      ANSI T1.112
      ANSI T1.112.4
      ANSI T1.118
      ANSI T1.111.6
      ANSI T1.112.5
      GR-2863-CORE, CCS Network Interface Specification Supporting Advanced
           Intelligent Network (AIN)
      GR-2902-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Toll-Free Service Using Advanced Intelligent Network (AIN)
      Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network User
           Part (ISDNUP)
      Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)
      ANSI T1.111-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
      ANSI T1.111A-1994, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP) 
           Supplement
      ANSI T1.112-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Signaling Connection Control Part
           (SCCP)
      ANSI T1.115-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Monitoring and Measurements for 
           Networks

                                 Sch. 2.3 - 3
<PAGE>
 
      ANSI T1.116-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Operations, Maintenance and
           Administration Part (OMAP)
      ANSI T1.118-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Intermediate Signaling Network
           Identification (ISNI)
      Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network User
           Part (ISDNUP)
      Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)

      Service Control Points (SCPs)/Call-Related Databases
      ----------------------------------------------------

      SR-TSV-002275 (BOC Notes on the Ameritech Networks, SR-TSV-002275, Issue
           2 (Bellcore, April 1994))
      GR-246-CORE, Bell Communications Research Specification of Signaling
           System Number 7, ISSUE 1 (Bellcore, December 1995)
      GR-1432-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Signaling Connection Control Part (SCCP) and Transaction 
           Capabilities Application Part (TCAP). (Bellcore, March 1994)
      GR-954-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Line Information Database (LIDB) Service 6, Issue 1, Rev. I
           (Bellcore, October 1995)
      GR-1149-CORE, OSSGR Section 10: System Interfaces, Issue 1 (Bellcore,
           October 1995) (Replaces TR-NWT-001149)
      GR-1158-CORE, OSSGR Section 22.3: Line Information Database 6, Issue
           (Bellcore, October 1995)
      GR-1428-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Toll Free Service (Bellcore, May 1995)
      BOC Notes on Ameritech Networks, SR-TSV-002275, ISSUE 2 (Bellcore, April
           1994)
      GR- 1280-CORE, AIN Service Control Point (SCP) Generic Requirements

      Tandem Switching
      ----------------

      Bellcore TR-TSY-000540, Issue 2R2, Tandem Supplement, 6/1/90
      GR-905-CORE
      GR-1429-CORE
      GR-2863-CORE
      GR-2902-CORE

      Performance Standards
      ---------------------

      Bellcore FR-64, LATA Switching Systems Generic Requirements (LSSGR)
  
                                 Sch. 2.3 - 4
<PAGE>
 
      Bellcore TR-NWT-000499, Issue 5, Rev 1, April 1992, Transport Systems
           Generic Requirements (TSGR): Common Requirements
      Bellcore TR-NWT-000418, Issue 2, December 1992, Generic Reliability
           Assurance Requirements For Fiber Optic Transport Systems
      Bellcore TR-NWT-000057, Issue 2, January 1993, Functional Criteria for
           Digital Loop Carriers Systems
      Bellcore TR-NWT-000507, Issue 5, December 1993, LSSGR - Transmission,
           Section 7
      Bellcore TR-TSY-000511, Issue 2, July 1987, Service Standards, a Module
           (Section 11) of LATA Switching Systems Generic Requirements (LSSGR,
           FR-NWT-000064)
      BELLCORE TR-NWT-000393, January 1991, Generic Requirements for ISDN
           Basic Access Digital Subscriber Lines
      Bellcore TR-NWT-000909, December 1991, Generic Requirements and
           Objectives for Fiber In The Loop Systems
      Bellcore TR-NWT-000505, Issue 3, May 1991, LSSGR Section 5, Call
           Processing
      Bellcore LSSGR TR-TSY-000511
      Bellcore TR-NWT-001244, Clocks for the Synchronized Network: Common
           Generic Criteria
      ANSI T1.105 -1995

      Network Interface Device
      ------------------------

      Bellcore Technical Advisory TA-TSY-000120, "Customer Premises or Network
           Ground Wire"
      Bellcore Generic Requirement GR-49-CORE, "Generic Requirements for Outdoor
           Telephone Network Interface Devices"
      Bellcore Technical Requirement TR-NWT-00239, "Indoor Telephone Network
           Interfaces"
      Bellcore Technical Requirement TR-NWT-000937, "Generic Requirements
           for Outdoor and Indoor Building Entrance"

Interconnection
- ---------------

     Trunking Interconnection
     -------------------------

     GR-317-CORE, Switching System generic requirements for Call Control
           Using the Integrated Services Digital Network User Part (ISDNUP),
           Bellcore, February, 1994

     GR-394-Core, Switching System generic requirements for Interexchange
           Carrier Interconnection Using the Integrated Services Digital Network
           User Part (ISDNUP), Bellcore, February, 1994

      FR-NWT-000064, LATA Switching Systems Generic Requirements (LSSGR),
           Bellcore, 1994 Edition
      ANSI T1. 111
      ANSI T1. 112
      ANSI T1. 113

                                 Sch. 2.3 - 5
<PAGE>
 
     Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message 
           Transfer Part (MTP), and Integrated Services Digital Network User 
           Part (ISDNUP)
     Bellcore GR-1428-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Toll-Free Service
     Bellcore GR-1429-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Call Management Services
     Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)
     ANSI T1.110-1992, American National Standard Telecommunications - 
           Signaling System Number 7 (SS7) - General Information;
     ANSI T1.111-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
     ANSI T1.111 A-1994, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
           Supplement
     ANSI T1.112-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Signaling Connection Control Part
           (SCCP)
     ANSI T1.113-1995, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Integrated Services Digital Network
           (ISDN) User Part 
     ANSI T1.114-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Transaction Capabilities
           Application Part (TCAP)
     ANSI T1.115-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Monitoring and Measurements for
           Networks
     ANSI T1.116-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Operations, Maintenance and
           Administration Part (OMAP)
     ANSI T1.118-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Intermediate Signaling Network 
           Identification (ISNI)
     Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network
           User Part (ISDNUP)
     Bellcore GR-954-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Line Information Database (LIDB) Service
     Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC Networks-
           Signaling
     Ameritech Supplement AM-TR-OAT-000069, Common Channel Signaling Network
           Interface Specifications
     Bellcore Standard FR-NWT-000476
     ANSI Standard T1.206

     Electrical/Optical Interfaces
     -----------------------------

     Bellcore Technical Publication TR-INS-000342, High Capacity Digital Special
           Access Service, Transmission Parameter Limits and Interface
           Combinations;

                              Sch. 2.3 - 6
<PAGE>
 
      Ameritech Technical Publication TR-NIS-000111, Ameritech 0C3, OC12 and
           OC48 Service Interface Specifications; and
      Ameritech Technical Publication AM-TR-NIS-000133, Ameritech 0C3, OC12 and
           OC48 Dedicated Ring Service Interface Specifications.

 Collocation
 -----------

     Bellcore Network Equipment Building Systems (NEBS) standards TR-EOP-000063
           National Electrical Code (NEC) use latest issue
     TA-NPL-000286, NEBS Generic Engineering Requirements for System Assembly
           and Cable Distribution, Issue 2 (Bellcore, January 1989)
     TR-EOP-000063, Network Equipment-Building System (NEBS) Generic Equipment
           Requirements, Issue 3, March 1988
     TR-NWT-000840, Supplier Support Generic Requirements (SSGR), (A Module of 
           LSSGR, FR-NWT-000064), Issue 1 (Bellcore, December 1991)
     TR-NWT-001275 Central Office Environment Installations/Removal Generic
           Requirements, Issue 1, January 1993
     Institute of Electrical and Electronics Engineers (IEEE) Standard 383, IEEE
           Standard for Type Test of Class 1 E Electrical Cables, Field Splices,
           and Connections for Nuclear Power Generating Stations
     National Electrical Code (NEC) use latest issue
     TA-NPL-000286, NEBS Generic Engineering Requirements for System Assembly
           and Cable Distribution, Issue 2 (Bellcore, January 1989)
     TR-EOP-000063, Network Equipment-Building System (NEBS) Generic Equipment
           Requirements, Issue 3, March 1988
     TR-EOP-000151, Generic Requirements for 24-, 48-, 130- and 140- Volt
           Central Office Power Plant Rectifiers, Issue 1 (Bellcore, May 1985)
     TR-EOP-000232, General Requirements for Lead-Acid Storage Batteries, Issue
           1 (Bellcore, June 1985)
     TR-NWT-000154, General Requirements for 24-, 48-, 130-, and 140- Volt
           Central Office Power Plant Control and Distribution Equipment, 
           Issue 2 (Bellcore, January 1992)
     TR-NWT-000295, Isolated Ground Planes: Definition and Application to
           Telephone Central Offices, Issue 2 (Bellcore, July 1992)
     TR-NWT-000840, Supplier Support Generic Requirements (SSGR), (A Module
     of LSSGR, FR-NWT-000064), Issue 1 (Bellcore, December 1991)
     TR-NWT-001275, Central Office Environment Installations/Removal Generic
           Requirements, Issue 1, January 1993 
     Underwriters' Laboratories Standard, UL 94

                              Sch. 2.3 - 7
<PAGE>
 
                                 SCHEDULE 3.8

               AMERITECH INTERCONNECTION PERFORMANCE BENCHMARKS

1.0   Trunk Provisioning Intervals

      1.1 Number of End Office
          Trunks Per Order Per Day               Interval
          ------------------------               --------
                             1-48                14 days
                             49-96               15 days
                             97+                 Negotiated
 
      1.2 New Trunk Groups to Tandem(s)          Negotiated
          -----------------------------

2.0   Trunking Grade of Service

      Blocking Standards

          Traffic Type                           Measurement
          ------------                           -----------
      Exchange Access Final Trunk Group Traffic  1/2 of 1% (0.005)
          via Tandems
      All Other Final Trunk Group Traffic        1% (0.01)

3.0  Truck Restoral 
     
          Type of Outage                         Interval
          --------------                         --------
      Service Affecting                          within 1 hour
      Non-Service Affecting                      within 24 hours


The Parties agree that additional Interconnection Performance Benchmarks may be
agreed upon by the Implementation Team. However, if any additional
Interconnection Performance Benchmarks require a Party to maintain records which
it then does not maintain, the Party requesting such new or additional
benchmarks shall utilize the Bona Fide Request process with respect to such
records.


                              Sch. 3.8 - 1
<PAGE>
 
                             SCHEDULE 3.9

                                 9-1-1 SERVICE

1.0   STANDARD FEATURES

      1.1. Forced Disconnect. Enables the PSAP attendant to release a connection
           -----------------                                                  
 on a 9-1-1 call, even if the calling party remains off-hook. The time required
to effect the forced disconnect varies as a function of the office type.

      1.2. Default Routing. Default Routing is activated when an incomong 9-1-1 
           ---------------
call cannot be selectively routed due to an ANI failure, garbled digits or other
causes. Such incoming calls are routed from the 9-1-1 Control Office to a
default PSAP if requested by the primary PSAP. Each incoming 9-1-1 facility
group to the Control Office is assigned to a designated default PSAP. Default
ANI and ALI data is provided when a call is Default Routed to indicate such
routing has taken place.

      1.3. Alternate Routing. Alternate Routing allows 9-1-1 calls to be routed
           -----------------
to a designated alternate location if (a) all 9-1-1 Service Lines to the
Primary PSAP are busy, or (b) the Primary PSAP closes down for a period (e.g,
                                                                         ---
night service).

      1.4. Central Office Transfer Arrangements:
           ------------------------------------

          1.4.1.    Manual transfer enables the PSAP attendant to transfer an
incoming call by depressing the switchhook of the associated telephone or the
"add" button on the Display and Transfer Unit and dialing either a 10-
digit telephone number, a 7-digit telephone number or a
2-digit speed calling code.

          1.4.2.    Fixed transfer enables a PSAP attendant to transfer incoming
9-1-1 calls to Secondary PSAPs by use of a single button on the Display and
Transfer Unit.

          1.4.3.    Selective transfer provides the PSAP with the ability to
transfer an incoming call to another responding agency by depressing a single
button labeled with the type of agency (e.g., "FIRE") on the Display and
                                        ---
Transfer Unit. Selective transfer is only available when Selective Routing is
provided.

2.0   9-1-1 MEET POINTS FOR PRIMARY AND DIVERSE ROUTES

      The point of Interconnection for Focal's Primary and Diverse Routes to the
mux/co-location and 9-1-1 Control Offices is at the Ameritech Central Office.
Focal shall pay tariff charges for Diverse routes. Focal will be responsible for
determining the proper quantity of trunks from its End Office(s) to the
Ameritech Central Office(s). Trunks between the Ameritech Central Office and the
Ameritech Control Office shall be delivered by Ameritech within twenty (20)
Business Days


                              Sch. 3.9 - 1
<PAGE>
 
following order by Focal. Following delivery, Focal and Ameritech will cooperate
to promptly test all transport facilities between Focal's network and the
Ameritech Control Office to assure proper functioning of the 9-1-1 service.


                                 Sch. 3.9 - 2
<PAGE>
 
                                 SCHEDULE 6.0

                       MEET-POINT BILLING RATE STRUCTURE

A   Interstate access - Terminating to or originating from Focal Customers
    served from an Focal local exchange End Office.

RATE ELEMENT                 BILLING
                                                 COMPANY

CCL                                              Focal                  
Local Switching                                  Focal
Interconnection charge                           Focal

Local Transport (Tandem) Termination             50% Ameritech
                                                 50% Focal

Local Transport (Tandem) facility                This will calculated based on  
                                                 NECA tariff No. 4 filings for
                                                 each Party
      
Tandem Switching                                 Ameritech      
Entrance Facility                                Ameritech 

B. Intrastate access - Terminating to or originating from Focal Customers served
   from an Focal local exchange End Office.
   
RATE ELEMENT                 BILLING
                                                 COMPANY

CCL                                              Focal
Local Switching                                  Focal
Interconnection Charge                           Focal
                
Local Transport (Tandem) Termination             50% Ameritech
                                                 50% Focal

Local Transport (Tandem) Facility                This will be caculated based 
                                                 on NECA tariff No. 4 filings
                                                 for each Party

     
                              Sch. 6.0 - 1
<PAGE>
 
Tandem Switching                                 Ameritech
Entrance Facility                                Ameritech
 

                                 Sch. 6.0 - 2
<PAGE>
 
                                SCHEDULE 9.2.1

                                 LOCAL LOOPS

      Subject to SECTION 1.1 of SCHEDULE 9.5, Ameritech shall allow Focal to
                 -----------    ------------
access the following Loop types (in addition to those Loops available under
applicable tariffs) unbundled from local switching and local transport.

      "2-WIRE ANALOG VOICE GRADE LOOP" OR "ANALOG 2W," which supports analog
transmission of 300-3000 Hz, repeat loop start, loop reverse battery, or ground
start seizure and disconnect in one direction (toward the End Office Switch),
and repeat ringing in the other direction (toward the Customer) and terminates
in a 2-Wire interface at both the central office MDF and the customer premises.
Analog 2W includes Loops sufficient for the provision of PBX trunks, pay
telephone lines and electronic key system lines. Analog 2W will be provided in
accordance with the specifications, interfaces, and parameters described in
Technical Reference AM-TR-TMO-000122, Ameritech Unbundled Analog Loops.

     "4-WIRE ANALOG VOICE GRADE LOOP" or "ANALOG 4W," which supports
transmission of voice grade signals using separate transmit and receive paths
and terminates in a 4-wire electrical interface at both ends. Analog 4W will be
provided in accordance with the specifications, interfaces, and parameters
described in Technical Reference AM-TR-TMO-000122, Ameritech Unbundled Analog 
Loops.

     "2-WIRE ISDN 160 KBPS DIGITAL LOOP" or "BRI-ISDN" which supports digital
transmission of two 64 Kbps bearer channels and one 16 Kbps data channel (2B+D).
BRI-ISDN is a 2B+D Basic Rate Interface-Integrated Services Digital Network
(BRI-ISDN) Loop which will meet national ISDN standards and conform to Technical
Reference AM-TR-TMO-000123, Ameritech Unbundled Digital Loops (Including ISDN).

     "2-WIRE ADSL-COMPATIBLE LOOP" or "ADSL 2W" is a transmission path which
facilitates the transmission of up to a 6 Mbps digital signal downstream (toward
the Customer) and up to a 640 kpbs digital signal upstream (away from the
Customer) while simultaneously carrying an analog voice signal. An ADSL-2W is
provided over a 2-Wire, non-loaded twisted copper pair provisioned using revised
resistance design guidelines and meeting ANSI Standard T1.413-1995 and AM TR-TM
O-000123. An ADSL-2W terminates in a 2-wire electrical interface at the Customer
premises and at the Ameritech Central Office frame. ADSL technology can only be
deployed over Loops which extend less than 18 Kft. from Ameritech's Central
Office. ADSL compatible Loops are available on1y where existing copper
facilities can meet the ANSI T1.413-1995 specifications.


                             Sch. 9.2.1 - 1
<PAGE>
 
      "2-WIRE HDSL-COMPATIBLE LOOP" OR "HDSL 2W" is a transmission path which
facilitates the transmission of a 768 Kbps digital signal over a 2-Wire, non-
loaded twisted copper pair meeting the specifications in ANSI T1E1 Committee
Technical Report Number 28. HDSL compatible Loops are available only where
existing copper facilities can meet the T1E1 Technical Report Number 28 and
AM-TR-TMO-000123 specifications.

      "4-WIRE HDSL-COMPATIBLE LOOP" OR "HDSL 4W" is a transmission path which
facilitates the transmission of a 1.544 Mbps digital signal over two 2-Wire,
non-loaded twisted copper pairs meeting the specifications in ANS1 T1E1 
Committee Technical Report Number 28 and AM TR-TMO-000123. HDSL compatible Loops
are available only where existing copper facilities can meet the T1E1 Technical
Report Number 28 specifications.

     "4-WIRE 64 KBPS DIGITAL LOOP" OR "4-WIRE 64 DIGITAL" is a transmission path
which supports transmission of digital signals of up to a maximum binary
information rate of 64 Kbps and terminates in a 4-Wire electrical interface at
both the Customer premises and on the MDF in Ameritech's Central Office. 4-Wire
64 Digital will be provided in accordance with the specifications, interfaces
and parameters described in AM-TR-TM-000123.

     "4-WIRE 1.554 MBPS DIGITAL LOOP" OR "1.544 MPBS DIGITAL" is a transmission
path which supports transmission of digital signals of up to a maximum binary
information rate of 1.544 Mpbs and terminates in a 4-Wire electrical interface
at the Customer premises and on the DSX frame in Ameritech's Central Office.
1.544 Mbps Digital will be provided in accordance with the specifications,
interfaces and parameters described in AM-TR-TMO-00023.


                             Sch. 9.2.1 - 2
<PAGE>
 
                                SCHEDULE 9.2.2
 
                 UNBUNDLED ACCESS TO NETWORK INTERFACE DEVICES
 
     Ameritech's Network Interface Device ("NID") is a Network Element that
utilizes a cross-connect device to connect loop facilities to inside wiring.
 
     Ameritech will permit Focal to connect Focal's loop to the inside wiring of
the Customer's premises through Ameritech's NID, where necessary. Focal must
establish the connection to Ameritech's NID through an adjoining NID which
serves as the network interface or demarcation for Focal's loop.

     Maintenance and control of premises (inside wiring)is under the control of
the Customer. Any conflicts between service providers for access to the
Customer's inside wire must be resolved by the Customer.
 

                                  Sch.9.2.2-1
<PAGE>
 
                                SCHEDULE 9.2.3


                             SWITCHING CAPABILITY


1.0   LOCAL SWITCHING. The local switching capability of a Network Element is
      defined as:

      (1)  line-side facilities, which include the connection between a Loop
           termination at the Main Distribution Frame and a switch line card;

      (2)  trunk-side facilities, which include the connection between trunk
           termination at a trunk-side cross-connect panel and a switch trunk
           card; and

      (3)  all features, functions, and capabilities of the switch available
           from the specific port type (line side or trunk side port), which
           include:

                (a) the basic switching function of connecting lines to lines,
           lines to trunks, trunks to lines, and trunks to trunks, as well as
           the same basic capabilities made available to Ameritech's Customers,
           such as a telephone number, white page listing, and dial tone;

                (b) access to operator services, directory assistance and 9-1-1
           and

                (c) all other features that the switch provides, including
           custom calling, CLASS features and Centrex, as well as any
           technically feasible customized routing functions available from such
           switch.

When local switching is provided by Ameritech, Focal will receive Customer Usage
Data and billing information in accordance with the requirements of SECTION
                                                                    -------
10.16.
- -----
     
2.0  TANDEM SWITCHING
     
     2.1   The Tandem Switching Capability Network Element is defined as:

     (1)   an unbundled Network Element in Ameritech's Class 4 non-TOPS digital
           Tandem Switches, which includes Interconnection with the trunk at the
           Tandem Distribution Frame ("TDF") and the Tandem Switch trunk ports.

     (2)   the basic switching function of creating a temporary transmission
           path that connects Focal's trunks to the trunks of Ameritech, IXCs,
           ICOs, CMRS, and other LECs interconnected to the Tandem Switch.


                                Sch. 9.2.3 - 1
<PAGE>
 
     2.2 Interconnecting trunk types which can be switched include FGB, FGC, FGD
and Type II. Signaling support includes Rotary, MF, and SS7 and any signaling
conversions between these signaling formats.

     2.3 Variations in Tandem Switching equipment used to provide service in
specific locations may cause differences in the operation of certain features.

     2.4 The unbundled Tandem Switching Network Element will provide to Focal
all available basic Tandem Switching functions and basic capabilities that are
centralized in the Tandem Switch (and not in End Office Switches), including the
following functions Ameritech makes available to its Customers:

1.   Routing of calls from an inbound trunk to an outbound trunk based on
     destination digits.

     2     Routing of Equal Access or Operator Service calls from an inbound
           trunk to an outbound trunk based on the CIC forwarded by the inbound
           trunk.

     2.5 Translations, screening, blocking, and route indexing are provided if
technically feasible under the standard switching translations and screening in
use in that switch. A request for translations, screening, blocking, route
indexing other than what is available (i.e., features that the switch is capable
                                       ---
of providing) in that switch will be provided where technically feasible as a
Bona Fide Request. Ameritech will provide these features if technically feasible
and upon agreement by Focal to pay the applicable recurring and nonrecurring
costs of developing, installing, providing and maintaining the capability.
Variations in the Tandem Switching equipment or translation and screening used
to provide service in specific locations may cause differences in the operation
of the element.

                             S c h. 9.2.3 - 2
<PAGE>
 
                                SCHEDULE 9.2.4

                      INTEROFFICE TRANSMISSION FACILITIES

      Interoffice Transmission Facilities are Ameritech transmission facilities
dedicated to a particular Customer or carrier, or shared by more than one
Customer or carrier, used to provide Telecommunications Services between Wire
Centers owned by Ameritech or Focal, or between Switches owned by Ameritech or
Focal.

1.    Ameritech provides several varieties of unbundled transport facilities:

      1.1. Unbundled dedicated interoffice transport facility ("DEDICATED
TRANSPORT") is a dedicated facility connecting two Ameritech Central Offices
buildings via Ameritech transmission equipment. In each Central Office building,
Focal will Cross-Connect this facility to its own transmission equipment
(physically or virtually) Collocated in each Wire Center, or to other unbundled
Network Elements provided by Ameritech to the extent the requested combination
is technically feasible and is consistent with other standards established by
the FCC for the combination of unbundled Network Elements. All applicable
digital Cross-Connect, multiplexing, and Collocation space charges apply at an
additional cost.

      1.2. "Unbundled dedicated entrance facility" is a dedicated facility
connecting Ameritech's transmission equipment in an Ameritech Central Office
with Focal's transmission equipment in Focal's Wire Center for the purposes of
providing Telecommunications Services.

      1.3. Shared transport transmission facilities ("SHARED TRANSPORT") are a
billing arrangement where two (2) or more carriers share the features, functions
and capabilities of transmission facilities between the same types of locations
as described for dedicated transport in SECTIONS 1.1 and 1.2 preceding and
                                        ------------     ---
share the costs.

2.   Ameritech shall offer Interoffice Transmission Facilities in each of the
following ways:

     2.1   As a dedicated transmission path (e.g., DS1, DS3, OC3, OC12 and OC48)
                                             ---
dedicated to Focal.

     2.2   As a shared transmission path as described in SECTION 1.3 above.
                                                         -----------

                                Sch. 9.2.4 - 1
<PAGE>
 
3.   Where Dedicated Transport or Shared Transport is provided, it shall include
     (as appropriate):

     3.1. The transmission path at the requested speed or bit rate.

     3.2. The following optional features are available; if requested by Focal,
at additional cost:

           3.2. 1. Clear Channel Capability per 1.544 Mpbs (DS1) bit stream.

           3.2.2. Ameritech provided Central Office multiplexing:

                  (a)  DS3 to DS1 multiplexing; and

                  (b)  DS1 to Voice/Base Rate/128, 256, 384 Kpbs Transport
                       multiplexing.

     3.3  If requested by Focal, the following are available at an additional
cost:

          3.3.1.  1+1 Protection for OC3, OC12 and OC48.

          3.2.2.  1+1 Protection with Cable Survivability for OC3, OC12 and
                  OC48.

          3.3.3.  1+1 Protection with Route Survivability for OC3, OC12 and
                  OC48.

 4.   Technical Requirements.

      This Section sets forth technical requirements for all Interoffice
      Transmission Facilities:

      4.1. When Ameritech provides Dedicated Transport as a circuit, the entire
designated transmission facility (e.g., DS1, DS3, and where available, STS-1)
shall be dedicated to Focal designated traffic.

      4.2. Ameritech shall offer Dedicated Transport in all then currently
available technologies including, DS1 and DS3 transport systems, SONET Bi-
directional Line Switched Rings, SONET Unidirectional Path Switched Rings, and
SONET point-to-point transport systems (including linear add-drop systems), at
all available transmission bit rates, except subrate services, where available.

      4.3. For DS1 facilities, Dedicated Transport shall, at a minimum, meet
the performance, availability, jitter, and delay requirements specified for
Customer Interface to Central Office "CI to CO" connections in the applicable
technical references set forth under Dedicated and Shared Transport in the
Technical Reference Schedule.

      4.4. For DS3 and, where available, STS-1 facilities and higher rate
 facilities, Dedicated Transport shall, at a minimum, meet the performance,
 availability, jitter, and delay requirements specified for Customer Interface
 to Central Office "CI to CO" connections in the applicable

                                Sch. 9.2.4 - 2
<PAGE>
 
 technical references set forth under Dedicated and Shared Transport in the
 Technical Reference Schedule.

     4.5. When requested by Focal, Dedicated Transport shall provide physical
diversity. Physical diversity means that two circuits are provisioned in such a
way that no single failure of facilities or equipment will cause a failure on
both circuits.

     4.6. When physical diversity is requested by Focal, Ameritech shall
provide the maximum feasible physical separation between intra-office and inter-
office transmission paths (unless otherwise agreed by Focal).

     4.7. Any request by Focal for diversity shall be subject to additional
charges.

     4.8. Upon Focal's request and its payment of any additional charges,
Ameritech shall provide immediate and continuous remote access to performance
monitoring and alarm data affecting, or potentially affecting, Focal's traffic.

     4.9.  Ameritech shall offer the following interface transmission rates for
Dedicated Transport:

           4.9.1. DS1 (Extended SuperFrame - ESF, D4, and unframed applications
     (if used by Ameritech)):

           4.9.2. DS3 (C-bit Parity and M13 and unframed applications (if used
     by Ameritech) shall be provided):

           4.9.3. SONET standard interface rates in accordance with the
     applicable ANSI technical references set forth under Dedicated and Shared
     Transport in the Technical Reference Schedule. In particular, where STS-1
     is available, VT 1.5 based STS-Is will be the interface at an Focal
     service node.

     4.10. Upon Focal's request, Ameritech shall provide Focal with electronic
provisioning control of an Focal specified Dedicated Transport through Ameritech
Network Reconfiguration Service (ANRS) on the rates, terms and conditions in
F.C.C. Tariff No.2.

     4.11. Ameritech shall permit, at applicable rates, Focal to obtain the
functionality provided by DCS together with and separate from dedicated
transport in the same manner that Ameritech offers such capabilities to IXCs
that purchase transport services. If Focal requests additional functionality,
such request shall be made through the Bona Fide Request process.


                             Sch. 9.2.4 - 3
<PAGE>
 
                                SCHEDULE 9.2.5

                 SIGNALING NETWORKS AND CALL-RELATED DATABASES

1.0   SIGNALING TRANSFER POINTS.

      A Signaling Transfer Point (STP) is a signaling network function that
includes all of the capabilities provided by the signaling transfer point
switches (STPSs) and their associated signaling links which enable the
exchange of SS7 messages among and between switching elements, database
elements and signaling transfer point switches.

1.1. TECHNICAL REQUIREMENTS.

     1.1.1. STPs shall provide access to all other Network Elements connected to
Ameritech SS7 network. These include:


            1.1.1.1.     Ameritech Local Switching or Tandem Switching;

            1.1.1.2.     Ameritech Service Control Points/Databases;

            1.1.1.3.     Third-party local or tandem switching systems, and
   
            1.1.1.4.     Third-party-provided STPSs.

     1.1.2.  The connectivity provided by STPs shall ful1y support the functions
of all other Network Elements connected to the Ameritech SS7 network. This
explicitly includes the use of the Ameritech SS7 network to convey messages
which neither originate nor terminate at a Signaling End Point directly
connected to the Ameritech SS7 network (i.e., transient messages). When the
                                        ---
Ameritech SS7 network is used to convey transient messages, there shall be no
alteration of the Integrated Services Digital Network User Part (ISDNUP) or
Transaction Capabilities Application Part (TCAP) user data that constitutes the
content of the message.


     1.1.3. If an Ameritech Tandem Switch routes calling traffic, based on
dialed or translated digits, on SS7 trunks between an Focal local switch and
third party local switch, the Ameritech SS7 network shall convey the TCAP
messages that are necessary to provide Call Management features (Automatic
Callback, Automatic Recall, and Screening List Editing) between the Focal local
STPSs and the STPSs that provide connectivity with the third party local switch,
even if the third party local switch is not directly connected to the Ameritech
STPSs, based on the routing instruction provided in each message.


                                Sch. 9.2.5 - 1
<PAGE>
 
      1.1.4. STPs shall provide all functions of the MTP as specified in ANSI
             T1.111. This includes:

             1.1.4.1. Signaling Data Link functions, as specified in 
                      ANSI T1.111.2:

             1.1.4.2. Signaling Link functions, as specified in ANSI T1.111.3;
                      and

             1.1.4.3. Signaling Network Management functions, as specified in
                      ANSI T1.111.4.

      1.1.5. STPs shall provide all functions of the SCCP necessary for Class 0
(basic connectionless) service, as specified in ANSI T1.112. In particular, this
includes Global Title Translation (GTT) and SCCP Management procedures, as
specified in T1.112.4. In cases where the destination signaling point is an
Ameritech local or tandem switching system or database, or is an Focal or third
party local or tandem switching system directly connected to the Ameritech SS7
network, STPs shall perform final GTT of messages to the destination and SCCP
Subsystem Management of the destination. In all other cases, STPs shall perform
intermediate GTT of messages to a gateway pair of STPSs in an SS7 network
connected with the Ameritech SS7 network, and shall not perform SCCP Subsystem
Management of the destination.

      1.1.6. STPs shall also provide the capability to route SCCP messages based
on ISNI, as specified in ANSI T1.118, when this capability becomes available on
Ameritech STPSs.

      1.1.7. STPs shall provide all functions of the OMAP commonly provided
by STPSs. This includes:

             1.1.7.1. MTP Routing Verification Test (MRVT); and

             1.1.7.2. SCCP Routing Verification Test (SRVT).

      1.1.8. In cases where the destination signaling point is an Ameritech
local or tandem switching system or database, or is an Focal or third party
local or tandem switching system directly connected to the Ameritech SS7
network, STPs shall perform MRVT and SRVT to the destination signaling point. In
all other cases, STPs shall perform MRVT and SRVT to a gateway pair of STPSs in
an SS7 network connected with the Ameritech SS7 network. This requirement shall
be superseded by the specifications for Internetwork MRVT and SRVT if and when
these become approved ANSI standards and available capabilities of Ameritech
STPSs.

      1.1.9. STPs shall be equal to or better than the following performance
             requirements:

             1.1.9.1. MTP Performance, as specified in ANSI T1.111.6; and

             1.1.9.2. SCCP Performance, as specified in ANSI T1.1125.


                                Sch. 9.2.5 - 2
<PAGE>
 
1.2.  SIGNALING LINK TRANSPORT.

      1.2.1. Definition. Signaling Link Transport is a set of two (2) or four
(4) dedicated 56 Kbps transmission paths between Focal-designated Signaling
Points of Interconnection (SPOI) that provides appropriate physical diversity.

Technical Requirements.

      1.2.2. Signaling Link Transport shall consist of full duplex mode 56 Kbps
transmission paths.

      1.2.3. Of the various options available, Signaling Link Transport shall
perform the following two (2) ways:


             a) As an "A-link" which is a connection between a switch or SCP and
             a Signaling Transfer Point Switch (STPS) pair; and

             b) As a "D-link" which is a connection between two (2) STP mated
             pairs in different company networks (e.g., between two (2) STPS
                                                  ---
             pairs for two Competitive Local Exchange Carriers (CLECs)).

      1.2.4. Signaling Link Transport shall consist of two (2) or more signaling
link layers as follows:

             a)   An A-link layer shall consist of two (2) links.

             b)   A D-link layer shall consist of four (4) links.

      1.2.5. A signaling link layer shall satisfy a performance objective such
that:

             a)   There shall be no more than two (2) minutes down time per year
                  for an A-link layer; and

             b)   There shall be negligible (less than two (2) seconds) down
                  time per year for a D-link layer.

      1.2.6. A signaling link layer shall satisfy interoffice and intraoffice
diversity of facilities and equipment, such that:

             a)   No single failure of facilities or equipment causes the
             failure of both links in an A-link layer (i.e., the links should be
                                                       ---          
             provided on a minimum of two (2) separate physical paths end-to-
             end); and


                                Sch. 9.2.5 - 3
<PAGE>
 
           b)   No two (2) concurrent failures of facilities or equipment shall
           cause the failure of all four (4) links in a D-link layer (i.e., the
                                                                      ---
           links should be provided on a minimum of three (3) separate physical
           paths end-to-end).

    1.2.7. Interface Requirements. There shall be a DS1 (1.544 Mbps) interface
at the Focal-designated SPOI. Each 56 Kbps transmission path shall appear as a
DSO channel within the DS1 interface.

    2.1.   TOLL FREE DATABASE SERVICES.

    2.1.1. Call Routing Service. The Call Routing Service provides for the
           --------------------
identification of the carrier to whom a call is to be routed when a toll-free
(1+800-NXX-XXXX or 1+888-NXX-XXXX) call is originated by Customer. This function
uses the dialed digits to identify the appropriate carrier and is done by
screening the full ten digits of the dialed number. The Call Routing Service may
be provided in conjunction with a Customer's InterLATA or IntraLATA Switched
Exchange Access Service.

      When 800 Call-Routing service is provided, an originating call is
suspended at the first switching office equipped with a Service Switching Point
(SSP) component of the SSC/SS7 Network. The SSP launches a query over signaling
links (A-links) to the Signal Transfer Point (STP), and from there to the SCP.
The SCP returns a message containing the identification of the carrier to whom
the call should be routed and the call is Processed.

      Focal's SS7 network is used to transport the query from its End Office to
the Ameritech SCP. Once Focal's identification is provided, Focal may use the
information to route the toll-free traffic over its network. In these cases,
Ameritech Switched Access services are not used to deliver a call to Focal. The
toll-free carrier ID data may not be stored for Focal's future use.

      2.1.2. Routing Options. In addition to the toll-free service offerings, 
             ---------------
new routing options are offered. These options are purchased by toll-free
service providers to allow their clients to define complex routing requirements
on their toll-free service. Toll-free routing options allow the service
provider's Customer to route its toll-free calls to alternate carriers and/or
destinations based on time of day, day of week, specific dates or other
criteria. These routing options are in addition to the basic toll-free call
routing requirements which would include the toll-free number, the intraLATA
carrier, the interLATA carrier and the Area of Service (AOS).

      2.1.3. Carrier Identification. Focal may choose the 800 Carrier
             ----------------------
Identification service to obtain toll-free number screening. With this service,
Focal will launch a query to the Ameritech database using its own Service
Switching Points (SSPs) network. In contrast to the Call Routing Service
described in Section 2.1.1 above, with the 800 Carrier Identification service,
             -------------
no routing is performed.

      2.1.4. Number Administration. Focal, at its option, may elect to use
             ----------------------                                       
Ameritech's toll-free Service which includes toll-free Number Administration
Service (NAS). With this service,


                                Sch. 9. 2.5 - 4
<PAGE>
 
Ameritech will perform the Responsible Organization service, which involves
interacting, with the national Service Management System (SMS/800), on behalf of
the Customer. Responsible Organization services include activating, deactivating
and maintaining 800/888 number records as well as trouble referral and
clearance. If Focal does not select NAS, Focal will perform the Responsible
Organization service.

     2.2.   LIDB DATABASE SERVICE.

     2.2.1. The Line Information Database (LIDB) Query Response Service is a
validation database system. It enables Focal to offer alternately billed
services to its Customers. The database provides an efficient way to validate
calling cards and toll billing exception (TBE) (i.e., restricts a collect or
                                                ---
third-party billed call). Toll fraud protection and reduced call set up expenses
are among the benefits of the service.

     2.2.2. Billing information records include the Customer name, phone number
security personal identification numbers and third-party acceptance indications.
Prior to call completion, a query is launched to the LIDB to determine the
validity of the requested billing method. The call is then completed or denied
based on the LIDB's response.

     2.3.   CNDS DATABASE SERVICE.

            2.3.1 Caller ID identifies a calling party's telephone number
            through a switch-based feature installed in Ameritech's Central
            Office. CNDS is a CCIS/SS7 network based feature that accesses a
            CNDS database within the LIDB to provide a name associated with the
            calling party's telephone number. This service is provided using TR
            1188 protocol.

            2.3.2 A Customer who subscribes to Caller ID with Name will see the
            listed name associated with the calling party's telephone line
            displayed on his/her Caller ID display unit. The telephone number
            associated with the telephone line of the calling party will also be
            displayed.

            2.3.3 Ameritech shall charge Focal for the CNDS Database Service in
            a similar manner to that which Ameritech charges Focal for the LIDB
            Database Service, including a per query charge.

     2.4    LOCAL NUMBER PORTABILITY.

            2.4.1 Ameritech's provision of LNP will utilize LRN switch software
     based on requirements developed by the workshop participants and concurred
     in by the Commission. These requirements are fully compliant with the
     principles adopted by the FCC in its First Report and Order, CC Docket No.
     95-116 (the "Number Portability Order"). The detailed description and
     technical specifications for the planned LRN implementation can be found in
     various documents produced by the FCC Local Number Portability workshop.


                                Sch. 9.2.5 - 5
<PAGE>
 
          2.4.2 Ameritech is fully prepared to provide LNP database access to
     Focal. However, in adopting its Number Portability Order, the FCC referred
     certain technical and other issues to the North American Numbering Council
     (NANC) and issued a further notice addressing the recovery of costs
     associated with LNP implementation. Until these activities are concluded,
     Ameritech cannot finalize product descriptions and rates for access to its
     LNP database. Nonetheless, Ameritech is willing to begin discussions with
     Focal to discuss Focal's access to Ameritech's LNP databases in lieu of
     constructing Focal's own.

     2.5. UNBUNDLED AIN APPLICATION PROCESS.

     2.5.1. The AIN architecture establishes a network infrastructure in which
subscriber services can be defined and implemented independent from End-Office
Switches. This is accomplished by a combination of SS7 signaling, interfaces
between Network Elements and call-state models through which AIN Network
Elements interact.

     2.5.2. Ameritech's Unbundled AIN (Advanced Intelligent Network)
Applications Access service will be provided on a nondiscriminatory basis and
enable Focal (whether it purchases unbundled switching capabilities from
Ameritech or owns its own SSP (Service Switching Point)) to offer its Customers
AIN services. Ameritech will make available existing AIN retail applications, as
well as newly created services that Focal creates via the Ameritech AIN Service
Creation Environment (SCE) Access service. Unbundled AIN Applications Access
provides for the AIN functionality necessary for the day to day ongoing call
processing associated with a specific AIN applications execution. This includes
the SS7 transport and SCP processing of the query associated with the specific
service.

     2.5.3. Associated with the AIN SCP is a Service Creation Environment (SCE)
and a Service Management System (SMS). Ameritech offers access to the Ameritech
SMS and SCE capabilities via two (2) AIN offerings: AIN Service Creation
Environment Access Service and AIN Service Management System Access Service.

     2.5.4. Carriers will share the common AIN infrastructure components
provided by Ameritech, such as a Service Control Point (SCP), a Signaling
Transfer Point (STP), Service Management System (SMS), and, if Focal purchases
Unbundled Switching from Ameritech, the AIN Service Switching Point (SSP). Focal
shall be responsible for assuring the compatibility of its AIN SSP software
generics with the Ameritech AIN Applications and SCP software releases.
Interconnection of the Focal SSP with the Ameritech SS7 network is required, and
can be accomplished in a number of ways.

     2.5.5. Activation of the desired application at the Ameritech SCP requires
subscription by both the ordering carrier Focal and the end-user. In general,
AIN operations require close cooperation between Ameritech and the requesting
Carrier.

                                Sch. 9.2.5 - 6
<PAGE>
 
     2.5.6. The SSP AND SCP vendors provide logical capabilities which Ameritech
uses to create each AIN service. The SSP and SCP vendors have no knowledge of
the specific AIN Applications that Ameritech has created. Ameritech's AIN
deployment is based on AIN 0.1

     3.1.   AIN SERVICE CREATION ENVIRONMENT ACCESS SERVICE.

Access to Ameritech's AIN service creation functionality will be provided in a
nondiscriminatory manner to Focal to enable it to create new AIN services on
Ameritech's network. If Focal has a new AIN service concept, it can utilize all
or some of the features below to obtain a fully functional AIN service.
Ameritech will furnish Focal with a list of AIN Applications and the switches on
which such applications are available, including the software version of AIN on
such switch type. The following is a list of AIN service creation functions
available via this service offering:

            
     3.1.1. Service Concept Description: The description of service idea should
detail requirements such as: dialing patterns, information exchange,
announcements, voice prompts, expected service management screens and reports,
and CPE requirements. The AIN service creation functions made available to Focal
must be the same ones Ameritech uses, subject to any third party restrictions
Ameritech may be subject to.

     3.1.2. Creation of Technical Specification: Translation of a new service
description into a technical specification including engineering requirements
for Ameritech's network. The technical specification must detail how the service
interacts in the network, translated in network terms, should include any
expected/anticipated feature interaction discrepancies, and will include the
process flows on how the service traverses the network.

     3.1.3. Service Logic Design: The development of service design from SCP
perspective to include Algorithms, Data Structures and Flow Diagrams.

     3.1.4. Service Logic Coding: Development of machine logic in the SCE to
include tables, SIBBs, and other elements as necessary.

     3.1.5. Service Logic Testing: Service logic testing isolated within the to
SCE to ensure accuracy of compilation and code development and compliance with
Ameritech's AIN environment.

     3.1.6. SMS Interface Requirements: Development of Focal SMS interface
access including screens, flow-through interface and reports. This is required
to allow Focal to activate, update, modify, and administer Customer data
associated with the new service.

     3.1.7. Platform Access Logic Configuration: Service specific updates to
global infrastructure required to enable new service. Includes modification of
the access logic to enable a new service.

     3.1.8. Service Integration Testing (SIL): Intensive laboratory testing of
service in conjunction with all Ameritech Switch types and or provider switch
types and generics (as

                                Sch. 9.2.5 - 7
<PAGE>
 
necessary) to minimize potential feature interaction conflicts and negative
network reactions. Resources must be made available to Focal on a
nondiscriminatory basis.

     3.1.9.  Network Implementation: Conditioning of the SMS, SCP, SSP, or STP
to accept service including network translations, signaling connectivity,
dialing plans, and coordination of provisioning process.

                         
     3.1.10. Field Testing: Comprehensive controlled testing in a live switch
environment, possibly at Focal's SSP location.

     3.2.    AIN SERVICE MANAGEMENT SYSTEM ACCESS SERVICE.

                                                     
     3.2.1.  Access to Ameritech's AIN service management system functionality
will be provided in a nondiscriminatory manner to Focal to enable it to manage
AIN services located wholly within Ameritech's network (SCP & SSP) or to manage
AIN services where the service logic is located within Ameritech's SCP and the
Customer is served from Focal's AIN-compatible SSP. Upon request of Focal,
Ameritech shall provide Focal the unbundled AIN Applications Access service
product description and a list of existing Ameritech AIN applications.

     3.2.2.  The Service Management System (SMS) is the administration system
for the service logic and data in the Advanced Intelligent Network (AIN) Service
Control Point (SCP). The SMS contains the master copy of service level,
subscriber level and subscription level data. The SMS also contains a copy of
the service logic.

Logical access to the SMS will be managed by a set of programs designed by
Ameritech. These programs provide security for the data that resides on the AIN
platforms by allowing user access to only specific data that is appropriate to
the customer or carrier. Whether explicitly stated in this document or not, all
access to the SMS is managed through these programs. The only exceptions to
managed access to SMS functionality are for the Ameritech Network Services
organizations that administer the AIN platforms. They require direct access in
order to appropriately administer the platforms.

Mediated access to SMS functionality will be provided through interface programs
that will be developed for specific services. Focal will have access to all of
the data that the service requires in order to administer that service for its
Customers. This includes service level, subscriber level, and subscription level
data as well as any reports and measurement data that is mutually agreed upon by
Ameritech and Focal.

     3.2.3. Service Logic. The SMS receives a copy of the service logic and
service management logic from the Service Creation Environment (SCE) system.
After population of specific network level and service level data, the SMS
downloads a view of the service logic to the designated SCPs. The service
management logic remains in the SMS to complement SMS utilities in the
monitoring and administration of a specific service.

                                Sch. 9.2.5 - 8
<PAGE>
 
It is required that all of the Service Creation unit testing, System Integration
Lab (SIL) testing and Network Deployment Testing has been completed.

It may be necessary for Focal to negotiate timing and supply service specific
data before that service can be deployed in the appropriate SCPs. Ameritech,
however, is totally responsible for service logic deployment and initial SCP
memory load in its network. Focal will receive timing and supply of service
specific data in a nondiscriminatory manner.

     3.2.4. Service Administration. Service administration involves the
management of service level data which the service logic requires for its
execution. SMS supports the management of service specific common data. Any
changes to the data representation of the Ameritech network, which impact one or
more carrier services will be administered by Ameritech. Other Focal specific or
service specific data changes will be identified and administered by Focal.

                                Sch. 9.2.5 - 9
<PAGE>
 
                                SCHEDULE 9.2.6

                     OPERATIONS SUPPORT SYSTEMS FUNCTIONS

1.0  PRE-ORDERING, ORDERING AND PROVISIONING. Ameritech will use the interface
described in Section 10.13.2(a) (including the separate interface used for
             ------------------
ordering prior to the first quarter of 1997) for the transfer and receipt of
data necessary to perform the pre-ordering, ordering, and provisioning functions
(e.g., order entry, telephone number and due date selection). However, the
 ----
Access Services Request (ASR) interface will be used for the transfer of
information concerning the Network Elements and Combinations which Focal intends
to order in a specific Wire Center ("FOOTPRINT" or "TRUNK SIDE INFORMATION").

2.0  MAINTENANCE AND REPAIR. Ameritech will use the interface described in
SECTION 10.13.3 (A) for the transfer and receipt of data necessary to perform
- ---------------
the maintenance and repair functions (e.g., trouble receipt and trouble status).
                                      ---

3.0   BILLING. Ameritech will provide appropriate usage data to Focal to
facilitate Customer billing with attendant acknowledgments and status reports
and exchange information to process claims and adjustments.

                                Sch. 9.2.6 - 1
<PAGE>
 
                                SCHEDULE 9.2.7

                   OPERATOR SERVICES AND DIRECTORY SERVICES

1.0 OPERATOR SERVICES. Operator Services consist of the following services.

      1.1  Manual Call Assistance - manual call processing with operator
           ----------------------
involvement for the following:

           (a) Calling card - the Customer dials 0+ or 0- and provides operator
     with calling card number for billing purposes.

           (b) Collect - the Customer dials 0+ or 0- and asks the operator to
     bill the call to the called number, provided such billing is accepted by
                                         --------
     the called number.

           (c) Third number billed - the Customer dials 0+ or 0- and asks the
     operator to bill the call to a different number than the calling or called
     number.

           (d)  Operator assistance - providing local and intraLATA operator
     assistance for the purposes of:

                (1) assisting Customers requesting help in completing calls or
                    requesting information on how to place calls;

                (2) handling emergency calls;

                (3) handling credits and coin telephone local refund requests;
                    and

                (4) handling person-to-person calls.

           (e)  Operator Transfer Service ("OTS") - calls in which the Customer
     dials "0", is connected to an Ameritech operator and then requests call
     routing to an IXC subscribing to OTS. The operator will key the IXC's digit
     carrier identification code to route the Customer to the requested IXC's
     point of termination.

           (f)  BLV - Service in which operator verifies a busy condition on a
     line.

           (g)  BLVI - service in which operator, after verifying a busy line,
     interrupts the call in progress.

                                Sch. 9.2.7 - 1
<PAGE>
 
      1.2  Automated Call Assistance - mechanized call processing without 
           -------------------------
operator involvement for the following:

           (a) Automated calling card service ("ACCS") - the Customer dials 0
      and a telephone number, and responds to prompts to complete the billing,
      information.

           (b) Automated Alternate Billing Service ("AABS") -

               (1)  the Customer dials 0 and a telephone number and responds to
                    prompts to process the call and complete the billing
                    information (Customer branding not currently available).

               (2)  ACCS calculates charges, relates the charge to the Customer,
                    and monitors coins deposited before connecting the 1 +
                    intraLATA or interLATA call.

      1.3  Line Information Database ("LIDB") Validation - mechanized queries to
           --------------------------------------------- 
a LIDB for billing validation.

      1.4  Database Access - To the extent technically feasible, Ameritech will
           ---------------
provide access to databases used in the provisioning of Operator Services via
Focal's Bona Fide Request.

2.0   DIRECTORY ASSISTANCE. Directory Assistance ("DA") service shall consist of
the following services.

      2.1  Directory Assistance - those calls in which the Customer dial digits
           --------------------
designated by Focal to obtain Directory Assistance for local numbers located
within his/her NPA. Two listings will be provided per call.

      2.2  Branding - the ability to put messages on the front end of a DA call
           --------                                                           
that is directly trunked into Ameritech's DA switch.

      2.3  Information Call Completion - provides a Customer who has accessed
           ---------------------------
the DA service and has received a number from the Audio Response Unit ("ARU")
the option of having an intraLATA call completed by pressing a specific digit on
a touch tone telephone. Information Call Completion is only available to Focal
if it direct trunks its DA calls to Ameritech.

      2.4  Upon request, and through a technically feasible arrangement,
Ameritech will provide access to databases used in the provisioning of DA via
Focal's Bona Fide Request at rates that recover Ameritech's costs of developing,
providing and maintaining the service. Such unbundled access to the DA database
shall be for the purpose of having Focal's Telephone Exchange Service DA listing
in the area placed into Ameritech's DA database, or to enable Focal to read DA
listing in the database so that Focal can provide its own DA service.

                                Sch. 9.2.7 - 2
<PAGE>
 
3.0   RATE APPLICATION. Ameritech shall bill Focal the applicable rates on a
monthly basis, in accordance with the following methodology.

      3.1 Manual Call Assistance - operator call occurrences multiplied by the
          ----------------------                                             
per call rate. Total call occurrences shall include all processed calls, whether
or not they are completed.

      3.2 Automated Call Assistance (ACCS and AABS) - call occurrences
          -----------------------------------------
multiplied by the per call occurrence rate. Total call occurrences shall include
all processed calls, whether or not they are completed.

      3.3 LIDB Validation - validation occurrences mulitplied by the LIDB 
          ---------------
validation per occurrence rate. Total validation occurrences shall include all
validations, whether or not the call is completed. Ameritech will accumulate
operator occurrences, automated occurrences, and LIDB validation occurrences via
its Operator Services Call Analysis System ("OSCAS"). OSCAS utilizes TOPS AMA
recordings to produce monthly summaries of mecahnized and manual call
occurrences.

      3.4 BLV - operator call occurrences multiplied by the per call rate. Total
          ---
call occurrences shall include all processed calls whether or not they are 
completed.

      3.5 BLVI - operator call occurrences multiplied by the per call rate. 
          ----
Total call occurrences shall include all processed calls whether or not they are
completed.

      3.6 Lost Records. If Ameritech is responsible for lost, destroyed, or
          ------------
mutilated TOPS AMA recordings, Ameritech will not bill Focal for those calls for
which there are no records. Likewise, Ameritech shall not be held responsible by
Focal for lost revenue. However, if within ninety (90) days, actual data should
become available, Ameritech will bill Focal for those calls using actual data.

                                Sch. 9.2.7 - 3
<PAGE>
 
                                SCHEDULE 9.3.4

                                 COMBINATIONS


1.    Unbundled Element Platform with Operator Services and Directory Assistance
      --------------------------------------------------------------------------

Unbundled Loop
Local Switching
Operator Services and Directory Assistance
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

2.    Loop Combination
      ----------------

Unbundled Loop
Network Interface Device

3.    Switching Combination #1
      ------------------------

Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

                                Sch. 9.3.4 - 1
<PAGE>
 
                                SCHEDULE 9.3.5

               COMBINATIONS AVAILABLE THROUGH BONA FIDE REQUEST

1.    Loop/Network Combination
      ------------------------

Unbundled Loop
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

2.    Switching Combination #2
      ------------------------

Network Interface Device
Local Switching
Shared Transport
Dedicated Transport
SS7 Message Transfer & Connection Control
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

3.    Switching Combination #3
      ------------------------

Network Interface Device
Local Switching
Operator Systems
Shared Transport
Dedicated Transport
SS7 Message Transfer & Connection Control
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

                                Sch. 9.3.5 - 1
<PAGE>
 
4.    Switched Data Services
      ----------------------

Network Interface Device
Local Switching
Shared Transport
Dedicated Transport
Tandem Switching

5.    Unbundled Element Platform Without Operator Services and Directory
      ------------------------------------------------------------------
      Assistance
      ----------

Unbundled Loop
Local Switching
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases 
Tandem Switching

                                Sch. 9.3.5 - 2
<PAGE>
 
                                 SCHEDULE 9.5

                       PROVISIONING OF NETWORK ELEMENTS

1.0  GENERAL PROVISIONING REQUIREMENTS.

     1.1  Subject to the terms of Article IX, Focal may order and/or request
                                  ----------
          Elements either individually or as Combinations.

     1.2  The Combinations set forth on SCHEDULE 9.3.4 and any additional
                                        --------------
          Combination provided previously hereunder by Ameritech pursuant to
          the Bona Fide Request process shall be identified and described by
          Focal so that they can be ordered and provisioned as a Combination
          and shall not require the enumeration of each Network Element within
          that Combination on each provisioning order, provided that in each
                                                       --------            
          case Focal shall specify on each order the type of service to be
          provided as well as the engineering and routing characteristics
          (e.g. redundancy requirements and data transfer rates) Focal 
           ---  
          requests for such Combination.

     1.3  Focal may order from Ameritech multiple individual Network Elements on
          a single order without the need to have Focal send an order for each
          such Network Element if such Network Elements are (i) for a single
          type of service, (ii) for a single location and (iii) for the same
          account.

     1.4  Ameritech shall provide provisioning services to Focal Monday through
          Friday from 8:00 a.m. to 5:00 p.m. CST. Focal may request Ameritech to
          provide Saturday, Sunday, holiday, and/or off-hour provisioning
          services. If Focal requests that Ameritech perform provisioning
          services at times or on days other than as required in the preceding
          sentence, Ameritech shall quote, within three (3) Business Days of the
          request, a cost-based rate for such services. If Focal accepts
          Ameritech's quote, Ameritech shall perform such provisioning services.

     1.5  Ameritech shall provide a Single Point of Contact (each, a SPOC) for
          ordering and provisioning contacts and order flow involved in the
          purchase and provisioning of Ameritech's unbundled Network Elements or
          Combinations. The SPOCs shall provide an electronic interface twenty-
          four (24) hours a day, seven (7) days a week for all ordering and
          provisioning order flows. Each SPOC shall also provide to Focal a 
          toll-free nationwide telephone number (operational from 8:00 a.m. to 5
          p.m., Monday through Friday) which will be answered by capable staff
          trained to answer questions and resolve problems in connection with
          the provisioning of Network Elements or Combinations.

     1.6  Ameritech shall provide to Focal a single point of contact (the
          "UNBUNDLING ORDERING CENTER") for ordering unbundled Network Elements.
          A national toll-

                                 Sch. 9.5 - 1
<PAGE>
 
            free number will be provided from 7:00 a.m. to 5:00 p.m. CST,
            Monday through Friday. This Unbundling Ordering Center is
            responsible for order acceptance, order issuance, and return of the
            Firm Order Commitment (FOC) to Focal as specified in this Schedule
            9.5.

            In addition, Ameritech shall provide to Focal a single point of
            contact (the "UNBUNDLING SERVICE CENTER") for all provisioning,
            maintenance, repair, and cutover coordination. A national toll-free
            number will be provided from 6:30 a.m. to 12:00 a.m. CST Monday
            through Friday. Out of hours maintenance questions are handled by a
            "FOLD DOWN CENTER."

      1.7   Ameritech will recognize Focal as the Customer of Record of all
            Network Elements and agreed to Combinations ordered by Focal and
            will send all notices, invoices and pertinent Customer information
            directly to Focal.

      1.8   Ameritech may not initiate any disconnection or rearrangement of any
            Focal ordered Element or Combination, except as directed by Focal or
            as otherwise provided in this Agreement.

      1.9   When requested by Focal, Ameritech will schedule installation
            appointments with Ameritech's representative on the line with
            Focal's representative until Focal has access to Ameritech's
            scheduling system.

      1.10  Ameritech will provide Focal with a Firm Order Confirmation (FOC)
            for each order, within twenty-four (24) hours of Ameritech's receipt
            of that order, or within a different time interval agreed upon by
            the Implementation Team. The FOC must contain an enumeration of
            Focal's ordered Network Elements or Combination features, options,
            physical Interconnection, quantity, and Ameritech commitment date
            for order completion ("COMMITTED DUE DATE"), which commitment date
            shall be established on a nondiscriminatory basis with respect to
            installation dates for comparable orders at such time.

      1.11  Upon work completion, Ameritech will provide Focal electronically
            (unless otherwise notified by Focal) with an order completion per
            order that states when that order was completed. Ameritech shall
            respond with specific order detail as enumerated on the FOC and
            shall state any additional charges (e.g. time and materials charges)
                                                ---
            up to a previously agreed upon limit associated with that order.

                                 Sch. 9.5 - 2
<PAGE>
 
      1.12  Ameritech will perform pre-testing of Network Elements and
            Combinations in accordance with Ameritech's standards. At Focal's
            request, Ameritech will make available to Focal on a weekly batch
            basis any available test and turn-up results in support of the
            Network Elements or Combinations ordered by Focal. Focal shall be
            responsible for any costs incurred by Ameritech to provide copies of
            any available results. If Focal requests Ameritech to provide Focal
            with any test or turn-up results which Ameritech does not then
            generate, Focal shall request such results through the Bona Fide
            Request process.

      1.13  As soon as identified, Ameritech shall provide notification
            electronically of Focal orders that are incomplete or incorrect and
            therefore cannot be processed.

      1.14  As soon as identified, Ameritech shall provide notification
            electronically of any instances when Ameritech's Committed Due Dates
            are in jeopardy of not being met by Ameritech on any element or
            feature contained in any order for Network Elements or Combinations.
            Ameritech shall indicate its new committed due date as soon as such
            date is available.

      1.15  Within twenty-four (24) hours of Focal's request, Ameritech will
            perform cooperative testing with Focal (including trouble shooting
            to isolate any problems) to test Network Elements or Combinations
            purchased by Focal in order to identify any performance problems.

      1.16  Subject to ARTICLE IX, Network Elements and Combinations will be
                       --------                                             
            provisioned with a combination of customer-specific and bulk orders
            as specified by Focal.

      1.17  When Focal orders Network Elements or Combinations that are
            currently interconnected and functional and remain interconnected to
            the same adjacent Network Elements, such Network Elements and
            Combinations will remain interconnected and functional without any
            disconnection or disruption of functionality of such Network
            Elements. There shall be no charge for such interconnection.
            Consequently, for Ameritech retail Customers who simply wish to
            switch their local service providers and keep the same type of
            service provided through the same equipment, this method of ordering
            will accomplish this with no physical changes required in the
            existing Network Elements. Under these circumstances, it shall not
            be necessary for Focal to collocate equipment in Ameritech Central
            Offices to connect the unbundled Network Element. If shared Network
            Elements are used, Ameritech will be responsible for all
            engineering, provisioning and maintenance of these components to
            ensure they support the agreed-upon grade of service.

                                 Sch. 9.5 - 3
<PAGE>
 
      1.18  Ameritech shall provide to Focal upon request:

            (a) a list of all services and features technically available from
                each switch that Ameritech may use to provide Local Switching,
                by switch CLLI;

            (b) a listing by street address detail, of the service coverage area
                of each switch CLLI;

            (c) when available, all engineering design and layout information
                for each Network Element and Combination; provided that Focal 
                                                          --------
                shall pay Ameritech for the costs incurred by Ameritech to
                provide Focal with copies of such information;

            (d) a listing of all technically available functionalities for each
                Network Element or Combination; and

            (e) advanced information on the details and requirement for planning
                and implementation of NPA splits.

      1.19  Promptly after the Effective Date, /22/ Ameritech shall provide 
                                                --
Focal
                                                
            an initial electronic copy of the following information:

            (a) Street address verification; 
            (b) Switch identification by service address; and 
            (c) Switch feature verification.

            Electronic updates to such information shall be provided monthly to
            Focal as changes are made to such information.

      1.20  For orders of Network Elements (and INP with the installation of a
Loop) that require coordination among Ameritech, Focal and Focal's Customer,
Focal shall be responsible for any necessary coordination with the Focal
Customer.

2.0   UNBUNDLED LOCAL LOOP TRANSMISSION

      2.1   ACCESS TO UNBUNDLED LOCAL LOOPS.

            2.1.1 Focal shall access Ameritech's Unbundled Local Loops via
     Collocation or in accordance with Article IX of this Agreement at the
                                       ----------
     Ameritech Wire Center where that


_________________________

/22/ Since the terms of this Agreement are the result of Focal's adoption under
 --                                                                             
     Section 252(i) of the Act of the AT&T Agreement, the Parties agree that the
     term "Effective Date", for purposes of this SECTION 1.19 OF SCHEDULE 9.5,
                                                 ------------    ------------
     shall mean February 10, 1999.

                                 Sch. 9.5 - 4
<PAGE>
 
     element exists and each Loop shall be delivered to Focal's Collocation by
     means of a CrossConnection, which shall be an additional charge.

            2.1.2 Ameritech shall provide Focal access to its unbundled Loops at
     each of Ameritech's Wire Centers. In addition, if Focal requests one or
     more Loops serviced by Integrated Digital Loop Carrier or Remote Switching
     technoloy deployed as a Loop concentrator, Ameritech shall, where
     available, move the requested Loop(s) to a spare, existing physical Loop at
     no charge to Focal. If, however, no spare physical Loop is available,
     Ameritech shall within forty-eight (48) hours of Focal's request notify
     Focal of the lack of available facilities. Focal may then at its discretion
     make a Bona Fide Request for Ameritech to provide the unbundled Loop
     through the demultiplexing of the integrated digitized Loop(s).
     Notwithstanding anything to the contrary in this Agreement, the
     provisioning intervals set forth in SECTION 2.2.2 of this Schedule and the
                                         -------------
     Ameritech Network Element Performance Benchmarks set forth in SCHEDULE 9.10
                                                                   -------------
     of this Agreement shall not apply to unbundled Loops provided under this
     SECTION 2.1.2.
     -------------

            2.1.3 If Focal orders a Loop type and the distance requested on such
     Loop exceeds the transmission characteristics as referenced in the
     corresponding Technical Reference specified below, distance extensions may
     be requested where technically feasible to meet the specification using
     such distance extensions and additional rates and charges shall apply as
     set forth at Item V of the Pricing Schedule.

              Loop Type                     Technical Reference/Limitation

Electronic Key Line                      2.5 miles
ISDN                                     Bellcore TA-NWT-000393
HDSL 2W                                  T1E1 Technical Report Number 28
HDSL 4W                                  T1E1 Technical Report Number 28
ADSL 2W                                  ANSI T1.413-1995 Specification


2.2  PROVISIONING OF UNBUNDLED LOOPS.

     The following coordination procedures shall apply for conversions of "LIVE"
Telephone Exchange Services to unbundled Network Elements:

            2.2.1 Focal shall request unbundled Loops from Ameritech by
     delivering to Ameritech a valid electronic transmittal service order (a
     "SERVICE ORDER") using the electronic interface described on SCHEDULE 
                                                                  --------
     9.2.6. Within twenty-four (24) hours of Ameritech's receipt of a Service
     -----
     Order, Ameritech shall provide Focal the firm order

                                 Sch. 9.5 - 5
<PAGE>
 
      commitment ("FOC") date according to the applicable Ameritech Network
      Element Performance Benchmarks set forth in SECTION 9.10 of this Agreement
                                                  ------------
      by which the Loop(s) covered by such Service Order will be installed.

            2.2.2 Ameritech shall provision unbundled Loops in accordance with
     the time frames set forth on SCHEDULE 9.10 or within such other intervals
                                  -------------                              
     as agreed upon by the Parties.

            2.2.3 Ameritech agrees to coordinate with Focal at least forty-eight
     (48) hours prior to the due date a scheduled conversion date and time (the
     "SCHEDULED CONVERSION TIME") in the "A.M." (12:00 midnight to 12:00 noon)
     or "P.M." (12:00 noon to 12:00 midnight) (as applicable, the "CONVERSION
     WINDOW").

            2.2.4 Not less than one (1) hour prior to the Scheduled Conversion
     Time, either Party may contact the other Party and unilaterally designate a
     new Scheduled Conversion Time (the "NEW CONVERSION TIME"). If the New
     Conversion Time is within the Conversion Window, no charges shall be
     assessed on or waived by either Party. If, however, the New Conversion Time
     is outside of the Conversion Window, the Party requesting such New
     Conversion Time shall be subject to the following:

            If Ameritech requests the New Conversion Time, the applicable Line
            Connection Charge shall be waived; and

            If Focal requests the New Conversion Time, Focal shall be assessed a
            Line Connection Charge in addition to the Line Connection Charge
            that will be incurred for the New Conversion Time.

            2.2.5 Ameritech shall test for Focal dial-tone ("DIAL TONE TEST") at
     Ameritech's MDF for Focal's Virtual Collocated equipment or Physical
     Collocated equipment during a window not greater than forty-eight (48)
     hours but not less than eight (8) hours prior to the Scheduled Conversion
     Time (or New Scheduled Time, as applicable). Ameritech shall perform the
     Dial Tone Test at no charge until the termination of this Agreement.

            2.2.6 Except as otherwise agreed by the Parties for a specific
     conversion, the Parties agree that the time interval expected from
     disconnection of "LIVE" Telephone Exchange Service to the connection of an
     unbundled Network Element at the Focal Collocation interface point will be
     sixty (60) minutes or less. If a conversion interval exceeds sixty (60)
     minutes and such delay is caused solely by Ameritech (and not by a Delaying
     Event), Ameritech shall waive the applicable Line Connection Charge for
     such element. If Focal has ordered INP with the installation of a Loop,
     Ameritech will coordinate the implementation of INP with the Loop
     conversion during the sixty (60) minute interval at no additional charge.

                                 Sch. 9.5 - 6
<PAGE>
 
            2.2.7 Requests for maintenance or repair of unbundled Loops are
      initiated using the industry standard "electronic bonding" interface (EBI)
      and are handled by the Ameritech Unbundling Service Center ("USC"). The
      USC works with local Ameritech personnel to perform any manual testing
      that may be required to isolate the trouble.

3.0   NETWORK INTERFACE DEVICE CAPABILITY.

      3.1   Ameritech will provide Focal access to NIDs in a manner that will
permit Focal to connect its loop facilities to the Customer's inside wiring
through Ameritech's NID, as required. Focal shall establish this connection
through an adjoining NID provided by Focal.

      3.2   Due to the wide variety of NIDs utilized by Ameritech (based on
Customer size and environmental considerations), Focal may access the Customer's
inside wire by any of the following means:

                                                            
            (a) Where an adequate length of inside wire is present and
            environmental conditions permit, Focal may remove the inside wire
            from Ameritech's NID and connect that wire to Focal's NID;

            (b) Enter the Customer access chamber or "side" of "dual chamber"
            NID enclosures for the purpose of extending a connecterized or
            spliced jumper wire from the inside wire through a suitable "punch-
            out" hole of such NID enclosures;

            (c) Enter Ameritech's loop terminal enclosure located at a multiple
            dwelling unit ("MDU") for the purpose of accessing Customer
            premises inside wire and extending such wire to Focal's own
            adjoining NID; or

            (d) Request Ameritech to make other rearrangements to the inside
            wire terminations or terminal enclosure on a time and materials cost
            basis to be charged to the requesting party (i.e., Focal, its agent,
                                                         ---
            the building owner or the Customer).

      3.3   If Focal accesses the Customer's inside wire as described in SECTION
                                                                         -------
2.2(D), the time and materials charges will be billed to the requesting party
- ------
(i.e., Focal, the building owner or the Customer).
 ---

      3.4   In no case shall Focal remove or disconnect Ameritech's loop
facilities from Ameritech's NIDs, enclosures, or protectors.

      3.5   In no case shall Focal remove or disconnect ground wires from
Ameritech's NIDs, enclosures, or protectors.

      3.6   Maintenance and control of premises wiring (inside wire) is the 
responsibility of the Customer. Any conflicts between service providers for 
access to the Customer's inside wire must be resolved by the Customer.

                                 Sch. 9.5 - 7
<PAGE>
 
      3.7   Due to the wide variety of NID enclosures and outside plant
environments, Ameritech will work with Focal to develop specific procedures to
establish the most effective means of implementing this SECTION 3.0.
                                                        -----------
4.0   UNBUNDLED LOCAL SWITCHING

      4.1   Access to Unbundled Local Switching.
            -----------------------------------

            4.1.1 Focal shall access Ameritech's Unbundled Local Switching via
      Collocation or in accordance with ARTICLE IX of this Agreement at the
                                        ----------
      Ameritech Wire Center where that element exists and each line-side and/or
      trunk-side port will be delivered to Focal's Collocation by means of a
      Cross-Connection, which shall be an additional charge.

            4.1.2 Ameritech shall provide Focal access to its Unbundled Local
      Switching at each of Ameritech's Wire Centers and will provide Focal all
      available basic local switching functions and basic capabilities the
      switch is capable of providing which Ameritech currently makes available
      to its local Customers, or for which Ameritech OSS functions are capable
      of provisioning pursuant to a Bona Fide Request.

            4.1.3 Unbundled Local Switching also provides access to additional
      features and capabilities that the switch has available for activation.
      Focal has the capability of activating these features on a line-by-line
      basis via an electronic interface. The additional features available for
      activation on the basic Unbundled Local Switching include:

                  (a)  vertical features;
                  (b)  Custom Calling, Custom Local Area Signaling Service
                       features ("CLASS") features; and
                  (c)  Centrex features.

            4.1.4 Other basic and/or additional capabilities, functions and
      features that are not then available for activation on the switch may be
      requested as optional special capabilities. Ameritech will provide these
      special capabilities if technically feasible and upon Focal's Bona Fide
      Request. Focal will pay the applicable recurring and nonrecurring costs of
      developing, installing, providing and maintaining the requested
      capability.

            4.1.5 Unless already provided by Ameritech as a service offering,
     and if not, upon Focal's Bona Fide Request, Ameritech will provide any
     technically feasible customized local routing of traffic through Unbundled
     Local Switching by class of call (e.g., operator, directory assistance, 
                                       ----
     9-1-1, toll, local, etc.). Ameritech will develop and provide any requested
     customized routing the switch is capable of providing, upon agreement by
     Focal to pay recurring and nonrecurring costs of developing, installing,
     updating, providing and maintaining such custom routing.

                                 Sch. 9.5 - 8
<PAGE>
 
            4.1.6 Ameritech provides, on an optional basis, the ability to
     connect line-side ports and/or trunk-side ports within the same switch with
     a group of common attributes. An example, is a request for Unbundled Local
     Switching to provide a Centrex service with intercom calling within the
     system and with certain common features. The attributes available include
     intercom calling, group call pick-up, and Automatic Route Selection.
     Intercom calling is defined as the ability of the line-side ports to call
     one another by dialing 3-7 digits. Group call pick up is defined as
     allowing one line-side port to answer a call directed to another line-side
     port in the same call pick-up group. ARS is defined as the ability to route
     calls to a specific group of trunk-side ports.

            4.1.7 Ameritech will switch traffic through its local switching
     element in accordance with Ameritech standard switching translations and
     screening in use in that switch. The custom routing optional feature
     enables Focal to specify special routing, by class of call, of some or all
     traffic incoming into its unbundled local switch using any technically
     feasible routing capability of that switch. Variations in the End Office
     switching equipment used to provide service in specific locations may cause
     differences in the operation of certain features. Special routing
     capabilities that are not otherwise available (i.e., features that the
                                                    ----
     switch is capable Of providing) will be developed on an individual basis
     through the Bona Fide Request process and will be installed, updated,
     maintained and provided following Focal's agreement to pay the applicable
     costs.

     4.2    PROVISIONING OF UNBUNDLED LOCAL SWITCHING.

     The following coordination Procedures shall apply for conversions of "LIVE"
Telephone Exchange Services to unbundled Network Elements:

            4.2.1 Focal shall request Unbundled Local Switching from Ameritech
     by delivering to Ameritech a valid electronic transmittal service order (a
     "SERVICE ORDER") using the electronic interface described on SCHEDULE
                                                                  --------    
     9.2.6. In addition, pre-ordering functions are supported via electronic
     -----
     data interchange (EDI) format as utilized for Resale Services. Within
     twenty-four (24) hours of Ameritech's receipt of a Service Order, Ameritech
     shall provide Focal the firm order commitment ("FOC") date by which the
     Unbundled Local Switching ports covered by such Service Order will be
     installed.

               Where connection of the Unbundled Local Switching port(s) to
     customized routing is required by Focal, the specific custom routing
     pattern desired must already exist. In those instances where the custom
     routing pattern does not already exist, Focal may request the development
     and establishment of such customer routing, pattern via a Bona Fide
     Request. While the custom routing pattern is being developed, Focal may do
     one of the following: (a) defer activation of the Unbundled Local Switching
     port until the routing pattern is established, (b) offer the Customer
     resale on an interim basis, or (c) convert the existing basic office
     routing pattern. If Focal elects option (c) and later desires to convert
     the Unbundled Local Switching port using Ameritech's office routing
     pattern to a customized routing pattern, an additional Line Connection
     Charge will apply.


                              Sch. 9.5 - 9
<PAGE>
 
            4.2.2 Ameritech agrees to coordinate with Focal at least forty-eight
     hours prior to the due date a scheduled conversion date and time (the
     "SCHEDULED CONVERSION TIME") in the "A.M." (12:00 midnight to 12:00 noon)
     or "P.M." (12:00 noon to 12:00 midnight) (as applicable, the "CONVERSION
     WINDOW").

            4.2.3 Not less than one (1) hour prior to the Scheduled
     Conversion Time, either Party may contact the other Party and unilaterally
     designate a new Scheduled Conversion Time (the "NEW CONVERSION TIME"). If
     the New Conversion Time is within the Conversion Window, no charges shall
     be assessed on or waived by either Party. If, however, the New Conversion
     Time is outside of the Conversion Window, the Party requesting such New
     Conversion Time shall be subject to the following:

            If Ameritech requests the New Conversion Time, the applicable Line
            Connection charge shall be waived; and
            

            If Focal requests the New Conversion Time, Focal shall be assessed a
            Line Connection charge in addition to the Line Connection Charge
            that will be incurred for the New Conversion Time.

            4.2.4 Except as otherwise agreed by the Parties for a specific
     conversion, the Parties agree that the time interval expected from
     disconnection of "LIVE" Telephone Exchange Service to the connection of an
     unbundled Network Element at the Focal Collocation interface point will be
     sixty (60) minutes or less. If a conversion interval exceeds sixty (60)
     minutes and such delay is caused solely by Ameritech (and not by a Delaying
     Event), Ameritech shall waive the applicable Line Connection Charge for
     such element.

            If Focal has ordered INP with the installation of a Loop, Ameritech
     will coordinate the implementation of INP with the Loop conversion during
     the sixty (60) minute interval at no additional coordination charge (other
     than the applicable standard service order and line connection charges).

     Ameritech shall provide to Focal equivalent functionality of blocking calls
     (e.g.,900, 976 and international calls) as provided to Ameritech's retail
      ----    
    Customers.

            4.2.5 When ordering a Local Switching Element, Focal may order from
     Ameritech separate interLATA and intraLATA capabilities (i.e., 2 PICs where
                                                              ---
     available) on a line or trunk basis.

            4.2.6 Unless otherwise directed by Focal and to the extent
     technically feasible, when Focal orders a Network Element or Combination,
     all pre-assigned trunk or telephone numbers currently associated with that
     Network Element or Combination shall be retained without loss of feature
     capability.


                             Sch. 9.5 - 10
<PAGE>
 
     4.3    Tandem Switching.
            ----------------

            4.3.1 Tandem Switching creates a temporary transmission path
     between interoffice trunks that are interconnected at a switch for the
     purpose of routing a call or calls. Unbundled Tandem Switching is ordered
     using electronic interfaces. Trunk-side ports are ordered using the Access
     Service Request ("ASR") which provides for electronic ordering based on
     industry standards adopted through OBF. ASR is the process used as of the
     Effective Date to order Exchange Access Services. Both pre-ordering and
     ordering functions and access to associated Operations Support Systems
     functions are supported electronically through these interfaces.

            4.3.2 Ameritech will service, operate, and maintain the unbundled
     Tandem Switching for Focal at parity with the service, operation, and
     maintenance Ameritech provides to itself, its subsidiaries, Affiliates and
     any other person. Unless requested otherwise, where applicable and
     technically feasible, Ameritech will provide unbundled Tandem Switching
     using the same specifications, interfaces, parameters, intervals,
     procedures and practices it uses to provide comparable Tandem Switching for
     all other Customers and carriers. Any feature or function existing in the
     Tandem Switch will be provided to Focal on a non-discriminatory basis.
     Congestion control and overflow routing will be provided on a non-
     discriminatory basis.

            4.3.3 Tandem Switching performance will be measured to ensure parity
     with all other Telecommunications Carriers that are interconnected with
     Ameritech. Performance will be measured on switching, call recording, and
     network management controls.

            4.3.4 Switch downtime will be measured through FCC reportable
     incidents report. CPI Index will be measured calls blocked and customer out
     of service incidents.

            4.3.5 Electronic Billing Accuracy Centers (EBAC) measures billing
     errors from the CABS error hold file report. Ameritech employs RAVE/A&T
     which enables on-line investigation of AMA volumes and will alert EBAC to
     possible AMA recording failures.

            4.3.6 Congestion Control and overflow criteria are set by the use of
     NTMOS Surveillance system which polls EDAS and NMA data on call volumes
     and make busy standards. Ameritech sets automatic thresholds with preplan
     routing and overflow selection. The system is also monitored via a manual
     surveillance system early recognition of performance problems.

                             Sch. 9.5 - 11
<PAGE>
 
5.0   INTEROFFICE TRANSMISSION FACILITIES.

      Ameritech shall:

      5.1 Provide Focal exclusive use of Interoffice Transmission Facilities
dedicated to Focal, or use of the features, functions, and capabilities of
Interoffice Transmission Facilities shared by more than one Customer or carrier,
including Focal;

      5.2 Provide all technically feasible transmission facilities, features,
functions, and capabilities that Focal could use to provide Telecommunications
Services;

      5.3 Permit, to the extent technically feasible, Focal to connect such
interoffice facilities to equipment designated by Focal, including Focal's
Collocated facilities; and

      5.4 Permit, to the extent technically feasible, Focal to obtain the
functionality provided by Ameritech's digital cross-connect systems separate
from dedicated transport.

6.0   SIGNALING NETWORKS AND CALL-RELATED DATABASES

      6.1  Signaling, Networks.
           -------------------

           6.1.1 If Focal purchases Switching Capability from Ameritech,
      Ameritech shall provide access to its signaling work from that switch in
      the same manner which Ameritech obtains access to such switch itself. In
      addition, Ameritech shall provide Focal access to Ameritech's signaling
      network for each of Focal's switches when Focal uses its own switching
      facilities. This connection shall be made in the same manner as Ameritech
      connects one of its own switches to an STP. Notwithstanding the foregoing,
      Ameritech shall not be required to unbundle those signaling links that
      connect Service Control Points to STPs or to permit Focal to link its own
      STPs directly to Ameritech's switch or call-related databases.

           6.1.2  If Focal has its own switching facilities, Ameritech shall
      provide Focal access to STPs to each of Focal's switches, in the same
      manner in which Ameritech connects one of its own switches to an STP, or
      in any other technically feasible manner (e.g., bringing an "A" link from
                                                ----
      Focal's switch to Ameritech's STP, or linking Focal's switch to its own
      STP and then connecting that STP to Ameritech's STP via a "B" or "D"
      link); provided that Ameritech shall not be required to (i) unbundle the
      signaling link connecting SCPs to STPs, (ii) permit direct linkage of
      Focal's own STPs to Ameritech's switch or call-related databases or (iii)
      unbundle an SCP from its associated STP.

           6.1.3  The Parties shall agree upon appropriate mediation facilities
      and arrangements for the Interconnection of their signaling networks and
      facilities, as necessary to adequately safeguard against intentional and
      unintentional misuse of the signaling networks and facilities of each
      Party. Such arrangements shall provide at a minimum:
      
                                 Sch. 9.5 - 12
<PAGE>
 
          .     Certification that Focal's switch is compatible with Ameritech's
                SS7 network;

          .     Certification that Focal's switch is compatible with Ameritech's
                AIN SCP;

          .     Certification that Focal's switch is compatible with a desired
                AIN application residing on Ameritech's SCP;

          .     Agreement on procedures for handling maintenance and
                troubleshooting related to AIN services;

          .     Usage of forecasts provided by Focal, so that Ameritech can
                provide suffficient SS7 resources for Focal and
                all other requesting Carriers;

          .     Mechanisms to control signaling traffic at agreed-upon levels,
                so that Ameritech's SS7 resources can be fairly shared by
                all requesting carriers;

          .     Mechanisms to restrict signaling traffic during testing
                and certification, as  necessary to minimize risks to the
                service quality experienced by Customers served by
                Ameritech's network and those of other carriers while
                compatibility and interconnection items are verified; and

          .     Mechanisms to ensure protection of the confidentiality of
                Proprietary Information of both carriers and Customers.

     6.2   Call-Related Databases.
           ----------------------

           6.2.1 For purposes of switch query and database response through a
     signaling network, Ameritech shall provide Focal access to its call-related
     databases, including the Line Information Database, Toll Free Calling
     database, downstream number portability databases, and Advanced intelligent
     Network databases by means of physical access at the STP linked to the
     unbundled database.

           6.2.2 If Focal purchases Unbundled Local Switching, Focal may, upon
     request, use Ameritech's SCP in the same manner, and via the same signaling
     links, as Ameritech. If Focal has deployed its own switch, and has linked
     that switch to Ameritech's signaling system, Focal shall be given access to
     Ameritech's SCP in a manner that allows Focal to provide any call- related,
     database-supported services to Customers served by Focal's switch. If the
     Implementation Team is unable to agree in the Implementation Plan to
     appropriate mediation mechanisms with respect to access to the AIN SCPs,
     the Parties shall adopt the mechanisms adopted by the Commission. Ameritech
     shall provide Focal access to call-related databases in a manner that
     complies with the CPNI requirements of Section 222 of the Act.

                             Sch. 9.5 - 13
<PAGE>
 
        6.2.3  The Parties shall agree upon appropriate mediation facilities
     arrangements for the Interconnection of their signaling networks,
     databases, and associated facilities, as necessary to adequately safeguard
     against intentional and unintentional misuse of the signaling networks and
     facilities of each Party. Such arrangements shall provide for at a minimum:

           .   Capabilities to protect each Party's information;
               
           .   Agreements on handling maintenance and troubleshooting related
               to AIN services;
               
           .   Usage forecasts provided by Focal so that Ameritech can provide
               sufficient resources for other requesting carriers, and
               capabilities to ensure that the Parties abide by such forecasts;
               
               
           .   Procedures to ensure, prior to deployment, that each service
               will properly operate within Ameritech's network;
               
           .   Procedures to verify proper deployment of each service in the
               network; and
               
           .   Mechanisms to ensure protection of the confidentiality of
               proprietary information of both carriers and customers.

      6.3  Service Management Systems.
           --------------------------

           6.3.1 Ameritech shall provide Focal with the information necessary to
     enter correctly, or format for entry, the information relevant for input
     into Ameritech's Service Management System ("SMS"). In addition, Ameritech
     shall provide Focal equivalent access to design, create, test, and deploy
     Advanced Intelligent Network.

           6.3.2 Access will provided in an equivalent manner to that which
     Ameritech currently uses to provide such access to itself (e.g.,
                                                                --- 
     submitting magnetic tapes if Focal inputs magnetic tapes, or through an
     electronic interface equivalent to that used by Focal). The Implementation
     Team shall set forth in the Implementation Plan the terms and conditions
     relating to such access. If the Implementation Team is unable to agree to
     appropriate mediation mechanisms with respect to access to the AIN SMSs and
     SCEs, the Parties shall adopt the mechanisms adopted by the Commission.

           6.3.3  Ameritech shall provide access to its SMS in a manner that
     complies with the CPNI requirements of Section 222 of the Act.

                             Sch. 9.5 - 14
<PAGE>
 
 7.0  OPERATIONS SUPPORT SYSTEMS FUNCTIONS

      7.1  Ameritech shall provide Focal access to Operations Support Systems
functions on or before the dates set forth on the Implementation Schedule.

      7.2  Ameritech shall also provide Focal access to the functionality of any
internal gateway systems Ameritech employs in performing the above-listed OSS
functions for its own Customers. A "gateway system" means any electronic
interface Ameritech has created for its own use in accessing support systems for
providing any of the above-listed OSS functions.

 8.0  OPERATOR SERVICES AND DIRECTORY SERVICES.

      8.1  Ameritech shall provide Focal access to Ameritech's Operator Service
and Directory Assistance facilities where technically feasible.

      8.2  Ameritech shall provide unbundled Operator Services ("OS") and
Directory Assistance ("DA") to Focal in conjunction with Telephone Exchange
Service provided to Focal as a purchaser of Resale Services and as an Unbundled
Local Switching Network Element or directly as a separate Network Element. A
list identifying the NPA/Exchange areas of Ameritech Directory Assistance, and
dependent Information Call Completion services will be provided to Focal and
will be updated as such DA services are provided in additional NPA/Exchange
Areas.

      8.3  Focal will obtain any required custom routing and obtain or provide
the necessary direct trunking and termination facilities to the mutually agreed
upon meet point with Ameritech facilities for access to unbundled OS and DA
services. Focal is responsible for delivering its OS and DA traffic to
Ameritech's operator service switch. Specifically, Focal shall deliver its
traffic direct from the End Office to the operator service switch location, and
there can be no Tandem Switching for OS. The operator service location to which
Focal will deliver its OS or DA traffic will be determined by Ameritech based on
the existing capacity of its service centers. Ameritech will, if technically
feasible, enable Focal to deliver its OS or DA traffic to the operator service
switch most closely located to the Focal's NPA/exchange originating the call.

      8.4  Ameritech will provide and maintain the equipment at its OS and DA
centers necessary to perform the services under this Agreement, with the goal of
ensuring that the OS and DA service meets current industry standards.

      8.5  Ameritech will provide OS and DA in accordance with its then current
internal operating procedures and/or standards.

      8.6  Ameritech will maintain a quality of service that will satisfy the
standards, if any, established by the Commission having Jurisdiction over the
provision of such service. Focal has the right, once annually, to visit each
Ameritech owned or subcontracted office upon reasonable notice to Ameritech or
with greater frequency by mutual consent of the Parties. Upon request, Ameritech

                             Sch. 9.5 - 15
<PAGE>
 
will provide monthly system results regarding speed of answer, average work time
and, for DA only, abandon from queue measurements.

      8.7  Focal is solely responsible for providing all equipment and
facilities to deliver OS and DA traffic to the point of Interconnection with
Ameritech facilities.

      8.8  Focal will provide and maintain the equipment at its offices
necessary to permit Ameritech to perform its services in accordance with the
equipment operations and traffic operations which are in effect in Ameritech's
DA and OS offices. Focal will locate, construct, and maintain its facilities to
afford reasonable protection against hazard and interference.

      8.9  Upon request and to the extent technically feasible, Ameritech will
unbundle OS and DA from resellers of its Telephone Exchange Service, and for
Focal, so Focal can provide its own OS or DA service or obtain it from a third
party. Also, upon request, Ameritech will provide unbundled OS and/or DA as a
stand alone unbundled Network Element to Focal. In either case, Focal is
required to obtain any required custom routing and to arrange for or provide
other facilities, services and Network Elements necessary to deliver its OS and
DA traffic to Ameritech's designated office, or to the office of another
provider, as applicable.

      8.10 Upon request, and as technically feasible, Ameritech will provide
through an electronic interface, unbundled access to its databases used to
provide DA and OS for purpose of enabling Focal to provide its own OS or DA
service, or as otherwise authorized by the FCC or the Commission. Such
unbundled access to DA and OS databases is provided as is technically feasible
based upon the facilities, equipment and software involved, and upon agreement
by Focal to pay to Ameritech its costs of developing, installing, providing and
maintaining such Network Element.

      8.11 Specifically, upon request, Ameritech will provide through an
electronic interface, unbundled access to its DA database to permit Focal to
have its local exchange directory assistance listings in the areas incorporated
into the database, and/or to read the DA listing (with the exception of non-
published listing) in that database for the purpose of providing its own DA
service. Such unbundled access will be provided in a technically feasible manner
based upon the facilities, equipment and software involved, and upon agreement
by Focal to pay to Ameritech its costs of developing, installing, providing and
maintaining such network element.
           
      8.12 Access of resellers and Focal to DA and OS of Ameritech, and the DA
and OS Network Elements provided hereunder, whether provided on a bundled or
unbundled basis, will, as applicable and as feasible, be provided through the
standard interfaces, parameters, intervals, service descriptions, protocols,
procedures, practices and methods that Ameritech uses for other customers of its
DA and OS services. Upon request, Ameritech will, as technically feasible,
provide a different quality of service, upon agreement by Focal to pay to
Ameritech its costs of developing, installing, maintaining maintaining and
repairing access to and provision of the Network Element at such quality of
service.

      8.13 Focal will furnish to Ameritech all information necessary for
provision of OS and DA. This information, to the extent it is identified as
such, shall be treated as Proprietary



                             Sch. 9.5 - 16
<PAGE>
 
Information. For OS this information includes emergency agency phone numbers,
rate information (such as mileage bands and operator surcharge information), and
originating screening information.  Focal will furnish to Ameritech all
information necessary for the provision of OS and DA.

            8.13.1  To the extent that Focal does not mirror Ameritech's
      operator surcharge rates, then Ameritech will, if technically feasible,
      enter Focal's surcharge rates into Ameritech's rate tables, and will
      charge Focal for changing those tables at the rates then charged by
      Ameritech for such service.

            8.13.2  For DA services, Focal will furnish Ameritech ninety (90)
     days (or such earlier time as the Parties may agree upon) before DA service
     is initiated details necessary ID to provide that service. This information
     includes listing information for the areas to be served by Ameritech and
     network information necessary to provide for the direct trunking of the DA
     calls.

            8.13.3  Focal will keep these records current and will inform
     Ameritech, in writing, at least thirty (30) days prior to any changes in
     the format to be made in such records. Focal will inform Ameritech of other
     changes in the records on a mutually agreed-upon schedule.
                    
     8.14   Upon request, and as technically feasible, Ameritech will re-brand
such OS and DA services based upon Focal's obtaining or providing any required
facilities, services, Network Elements and custom routing, and their agreement
to pay rates that compensate Ameritech for any costs it incurs in developing,
installing, providing and maintaining such rebranded service. For branding of
calls, Focal must provide two (2) cassette tapes of an announcement, no longer
than three (3) seconds, for installation on each OS and DA switch serving
Focal's Customers.

     8.15   Branding: Re-branding is available as follows:
            --------

                (a) Mechanized front-end branding is available for all manual
            and automated OS calls.

                (b) Mechanized back-end branding is available for automated
            calling card calls handled via ACCS.

                (c) On mechanized collect and billed-to-third calls, back-end
            branding is not currently available.

                (1) Such calls can be manually handled and branded.

                (2) If Customer desires mechanized branding, the feature can be
                    installed if Focal pays for feature purchase and
                    installation.

     Normally, OS and DA services, both bundled and unbundled, will be branded
     with Ameritech's name as the provider of the service. Upon request from
     Focal, and as technically

                             Sch. 9.5 - 17
<PAGE>
 
feasible, Ameritech will re-brand OS and DA traffic from Focal's telephone
exchange lines, or to Focal's unbundled OS or DA network element. Re-Network
Element. Re-branded service requires that Focal arrange to have the subject OS
or DA traffic delivered to Ameritech's Central Office on separate trunks, which
may require that it obtain custom routing, and obtain or provide such trunks and
other applicable.

      Re-branding is provided at rates that recover Ameritech's costs of
developing, installing, providing and maintaining such service. 

      8.16  Focal grants to Ameritech during the term of this Agreement a non-
exclusive license to use the DA listings provided pursuant to this Agreement. DA
listings provided to Ameritech by Focal under this Agreement will be maintained
by Ameritech only for providing DA information, and will not be disclosed to
third parties. This section does not prohibit Ameritech and Focal from entering
into a separate agreement which would allow Ameritech to provide or sell Focal's
DA listing information to third parties, but such provision or sale would only
occur under the terms and conditions of the separate agreement.

      8.17  Ameritech will supply Focal with call detail information so that
Focal can rate and bill the call. This information excludes rating and invoicing
of Customers, unless negotiated on an individual case basis.

                             Sch. 9.5 - 18
<PAGE>
 
                                 SCHEDULE 9.10

                    NETWORK ELEMENT PERFORMANCE ACTIVITIES


A.  Non-DS1 Loops-Standard Intervals
    Volume*                                  Interval         
    -------                                  --------        
     1-24                                    5 Business Days 
    25-48                                    6 Bus!ness Days 
    49-96                                    7 Business Days
    97+                                      Negotiated       
                          *Number of Loops Per Order Per Day

B.  DS1 Unbundled Local Transport

    1.   Facilities Available                7 Business Days

    2.   Force and Load                      Negotiated Interval 
         Not Available

C.  DS3-Unbundled Local Transport            Negotiated Interval

D.  OC-N-Unbundled Local Transport           Negotiated Interval

                             Sch. 9.10 - 1
<PAGE>
 
                                 SCHEDULE 10.1

                           WHOLESALE RESALE SERVICES

The Resale Services provided hereunder by Ameritech are those Telecommunications
Services set forth in the Resale Tariff(s). The rates for such Resale Services
are set forth in the Resale Tariff(s).

                                Sch. 10.1 - 1
<PAGE>
 
                                SCHEDULE 10.3.1
                 GRANDFATHERED SERVICES AND SUNSETTED SERVICES
                                   MICHIGAN
                                        
                             TARIFF MPSC NO. 20 R
<TABLE> 
<CAPTION>
<S>                                                      <C>                         <C> 
  TOPIC                                                  SECTION                     SHEET
  Automatic Voice Connecting Arrangements                    8                         4   
                                                                          
  Budget Toll Dialing Service                                9                        15   
                                                             
  Centrex - DS (Digital)                                     5                        38  
                                                                          
  Centrex IV                                                 5                         5 
                                                                          
  Centrex V                                                  5                        22  

  Channels for Key Telephone Systems                         8                         3

  Channels for Television Transmission for Use in           18                        17              
  Educational Television Systems              

  Channels for Television Transmission - Other Than for     18                         1              
  Use in Educational Television Systems                                 
                                                                          
  Circle Calling 30                                          9                        13
                                                            
  Circle Calling Service                                     9                        16
                                             
  Cross Boundary Rate Treatment for Direct High             15                         1
  Capacity Service                                                     
 
  Entrance Facilities                                       15                        90

  Equipment and Miscellaneous Charges (Private Line)        15                       134
                                                                           
  Foreign Telephone Service                                  4                         3             
  
  High Capacity Services                                    15                       144               
  
  Interexchange (Interzone) Channel Charges                 15                        92             
  
  Intraexchange (Intrazone) Channel Charges                 15                       114
  
  Local Distribution Channel                                15                         4           

  Municipal Emergency Reporting Service                      8                         1            
                                                                       
  Premiere Service                                           6                         1
                       
  Premiere 2/6 Service                                       6                         3
 
  Registered Equipment and Circuits (Private Line)          15                        65
  
  Rotary Business Service                                    4                         8
  
  Rotary Residence Service                                   4                         8
</TABLE> 
                                Sch. 10.3.1 - 1
                      
<PAGE>
 
<TABLE> 
<CAPTION> 
<S>                                                       <C>                             <C> 
TOPIC                                                     SECTION                         SHEET
Services Involved in Exchange Boundary Revisions            4                              1    

Special Protection Equipment                               15                              5

Subvoice Channel Services                                  15                              6

Universal Emergency Number Service (911)                    8                              2

Value Calling Plan                                          9                              4

Value Plus Contract Service                                 9                              1

Wideband Metallic Channel                                  15                              7
</TABLE> 


                               Sch. 10.3.1 - 2
<PAGE>
 
                                SCHEDULE 10.3.1

                GRANDFATHERED SERVICES AND SUNSETTED SERVICES            
                                   MICHIGAN                    
               
                                     OTHER

         TOPIC

         Apartment Door Answering Service

         Automatic Identified Outward Dialing (AIOD) Service 

         Automatic Intercept Service (A.I.S.)

         Automatic Voice Connecting Arrangements
         
         Business Interphone Service

         Centrex CO Systems - ESS

         Centrex CO Systems - No. 5X-BAR

         Centrex - DS

         Centrex - General

         Centrex IV

         Centrex V

         Centrex Mate

         Centrex Message Desk Interface

         Centrex - Special Features

         Centrex Station Call Through Test

         Concentrator-Identifier - Four Trunk Capacity

         Home Interphone Service

         Intercom Calling

         Lobby Interphone Service

         Semi-Public Telephone Service

         Time-of-Day Announcement Service

         Two-Way Intercommunications Arrangement

                               Sch. 10.3.1 - 3 
<PAGE>
 
         TOPIC
 
         Value Calling Plan (Sunsetted)
 
         Voice Calling Service
 
         WATS
                                
                               Sch. 10.3.1 - 4
 
<PAGE>
 
                            SCHEDULE 10.9.2

                        RESALE PERFORMANCE BENCH-MARKS

A.  Installation

    1.    Installation Intervals

          a.  POTS

              (1) Percentage Installed on Time

              (2) Installation Interval More Than Six (6) Days

          b.  HICAP: Percentage of Missed Appointments

SUBRATE: Percentage of Missed Appointments

    2.    New Service Failures

          a. POTS:      Percentage of New Service Failures During First Seven
                        (7) Days from Installation Date

          b. HICAP:     Percentage of New Service Failures During First Thirty
                        (30) Days from Installation Date
 
          c. SUBRATE:   Percentage of New Service Failures During First Thirty
                        (30) Days from Installation Date 

B.  Repair
 
    1.    Time to Repair
 
          a. POTS:      Percentage of Repairs Not Completed within twenty-four
                        (24) hours

          b. HICAP:     Percentage of Repairs Not Completed within two (2) hours

          c. SUBRATE:   Percentage of Repairs Not Completed within three and 
                        one-half (3 1/2) hours

    2.    Percentage of Initial Trouble Reports

    3.    Percentage of Code 4 Troubles

C.  Time to Provide Firm Order Commitment

    1.    Switched Services: Percentage of Firm Order Commitments Provided in
          four (4) days of Date of Order

    2.    HICAP Services: Percentage of Firm Order Commitments Provided
          within twenty-four (24) hours of Time of Order

                              Sch. 10.9.2 - 1
<PAGE>
 
D.  Speed of Answer

    1.    Service Center: Percentage of Calls to Service Center made during
          normal business hours that are answered within ten (10) seconds

    2.    Repair Center: Percentage of Calls to Repair Center that are answered
          within twenty (20) seconds.

    3.    Operator Services: Toll Assistance Speed of answer (seconds).
         
    4.    Operator Services: Directory Assistance Speed of answer (seconds). 

                                Sch. 10.9.2 - 2
<PAGE>
 
                                SCHEDULE 10.9.6

                               CREDIT ALLOWANCES
                                   MICHIGAN
                                        
1.   In the event of an interruption to the service provided pursuant to any of
     Sections 3.8, 9.10 or 10.9 by a Party (the "Providing Party") to the other 
     ------------  ----    ----
     Party (the "Receiving Party") which is not due to the negligence or willful
     act of Receiving Party or its Customer, upon notice and application by
     Receiving Party an allowance will be made for the time interruption
     continues.

2.   The liability of Providing Party for any credit allowance arising out of
     mistakes, omissions, interruptions, delays, errors or defects in
     transmission, or failures or defects in facilities furnished by the
     Providing Party, occurring in the course of furnishing service or other
     facilities and not caused by the negligence of Receiving Party or of
     Providing Party in failing to maintain proper standards of maintenance and
     operation and to exercise reasonable supervision shall in no event exceed
     an amount equivalent to the proportionate charge to Receiving Party for the
     period of service during which such mistake, omission, interruption,delay
     or error or defect in transmission or failure or defect in facilities
     occurs.

     The services furnished by Providing Party, in addition to the limitation
     set forth preceding, also are subject to the following limitation:
     Providing Party shall not be liable for any credit allowance arising out of
     mistakes, omissions, delays, errors or defects in transmission or other
     injury, including injuries to persons or property from voltages or currents
     transmitted over the service of Providing Party (a) caused by Receiving
     Party or Receiving Party Customer-provided equipment (except where a
     contributing cause is the malfunctioning of a Providing Party connecting
     arrangement, in which event the liability of the Providing Party shall not
     exceed an amount equal to a proportional amount of Providing Party billing
     for the period of service during which such mistake, omission,
     interruption, delay, error, defect in transmission or injury occurs), or
     (b) not prevented by Receiving Party or Receiving Party Customer-provided
     equipment but which would have been prevented had Providing Party-provided
     equipment been used.

3.   When the lines of other telecommunication providers or facilities of other
     persons are used in establishing connections to points not reached by the
     Providing Party's lines, the Providing Party is not liable for any act or
     omission of the other provider or persons.

                               Sch. 10.9.6 - 1
<PAGE>
 
                               SCHEDULE 10.11.1

                   FORM OF REPRESENTATION OF AUTHORIZATION

    Focal hereby represents to Ameritech, for purposes of obtaining a Customer's
Customer Proprietary Network information ("CPNI") or for placing an order to
change or establish a Customer's service, that it is a duly certificated LEC and
that it is authorized to obtain CPNI and to place orders for Telephone Exchange
Service (including Resale Service) upon the terms and conditions contained
herein.

1.  With respect to requests for CPNI regarding prospective Customers of Focal,
    Focal acknowledges that it must obtain written or electronic authorization
    in the form of a signed letter, tape-recorded conversation, password
    verification, or other means ("DOCUMENTATION OF AUTHORIZATION") which
    explicitly authorizes Focal to have access to the prospective Customer's
    CPNI. The Documentation of Authorization must be made by the prospective
    Customer or the prospective Customer's authorized representative. In order
    to obtain the CPNI of the prospective Customer, Focal must submit to
    Ameritech the Documentation of Authorization. If Focal cannot provide
    applicable Documentation of Authorization, then Ameritech shall not provide
    CPNI to Focal.

2.  If Focal has already obtained Documentation of Authorization for the
    Customer to place an order for Telephone Exchange Service for the Customer,
    Focal need not submit Documentation of Authorization to obtain the
    Customer's CPNI.

3.  With respect to placing a service order for Telephone Exchange Service
    (including Resale Services) for a Customer, Focal acknowledges that it must
    obtain Documentation of Authorization which explicitly authorizes Focal to
    provide Telephone Exchange Service to such Customer. The Documentation of
    Authorization must be made by the prospective Customer or Customer's
    authorized representative. Focal need not submit the Documentation of
    Authorization to process a service order. However, Focal hereby represents
    that it will not submit a service order to Ameritech unless it has obtained
    appropriate Documentation of Authorization from the prospective Customer and
    has such Documentation of Authorization in its possession.

4.  The Documentation of Authorization must clearly and accurately identify
    Focal and the prospective Customer.

5.  Focal shall retain all Documentation of Authorization in its files for as
    long, as Focal provides Telephone Exchange Service to the Customer, or for
    as long as Focal makes requests for information on behalf of the Customer.

6.  Focal shall make Documentation of Authorization available for inspection by
    Ameritech during normal business hours. In addition, Focal shall provide
    Documentation of Authorization for Customers or prospective Customers to
    Ameritech upon request.

6282481.4

                             Sch. 10. 11. 1 - I
<PAGE>
 
7.   Focal is responsible for, and shall hold Ameritech harmless from, any and
     all Losses (as defined in that certain Interconnection Agreement under
     Sections 251 and 252 of the Telecommunications Act of 1996 dated as of
     January 29, 1997 by and between Ameritech Information Industry Services, a
     division of Ameritech Services, Inc. on behalf of and as agent for
     Ameritech Michigan and Focal Communications Corporation of Michigan, (the
     "INTERCONNECTION AGREEMENT") resulting from Ameritech's reliance upon
     Focal's representations as to its authority to act on behalf of a Customer
     or prospective Customer in obtaining CPNI or placing a service order for
     Telephone Exchange Service.

8.   If Focal falls to repeatedly and materially abide by the procedures set
     forth herein, Ameritech reserves the right to insist upon the submission of
     Documentation of Authorization for each Customer in connection with a
     request for a service order.

9.   This Representation of Authorization shall commence on the date noted below
     and shall continue in effect until the termination or expiration of the
     Interconnection Agreement.

     Dated this _______ day of _____ 199.

FOCAL COMMUNICATIONS CORPORATION OF MICHIGAN

By:_______________________________
Title:____________________________
Printed Name:_____________________

                               Sch. 10.11.1 - 2
<PAGE>
 
                            SCHEDULE 10.12.6

                     LAW ENFORCEMENT INTERFACES

1.0  INTRODUCTION.

     Consistent with Applicable Law, it is necessary for Focal and Ameritech to
provide interface requirements to allow Focal to use a standard set of
procedures for meeting the requirements of applicable law enforcement agencies
("LAW ENFORCEMENT PROCESS"). The Law Enforcement Process will enable Focal to
provide identical services to its Customers. These services include Annoyance
Call Bureau, wire intercept, wire trap, wire trace, fraud control, physical
security and subpoena management.

2.0  LAW ENFORCEMENT.

    Definition - The Law Enforcement Process assures that Focal (as a reseller
of Resale Services) is in total compliance with law enforcement requirements
related to providing local Services to its Customers. Ameritech (switch owner
or access provider) agrees to support law enforcement requirements as provided
by the CALEA.

3.0  ANNOYANCE CALL BUREAU.

     3.1  Definition - Ameritech Annoyance Call Bureau (AACB) conducts
investigations to help determine who the unwanted callers are after victims
receive annoying calls and files an official complaint with the local law
enforcement agency. Annoying calls are: threatening, harassing, obscene, prank,
hang-ups, unwanted sales pitches, and survey calls. The information obtained
will only be released to the local law enforcement agency.

                       
     3.2  When Focal must initiate a wire trap or trace as a result of its
customer receiving an annoying call (e.g., threatening, harassing, obscene,
                                     ----
prank, hang-ups, unwanted sales pitches, and survey calls), the following
operational interfaces should occur:

          3.2.1.   Focal (the reseller) shall inform its Customer that they must
     file a formal complaint with the local police department and obtain
     agency's name, officer's name and case or report number.

          3.2.2.   Focal shall contact Ameritech Annoyance Call Bureau on behalf
     of its Customer and provide the required information to initiate trap or
     call trace.

          3.2.3    The AACB shall conduct investigations to determine who the
     unwanted caller is, work with local police departments to gather evidence:
     and even testify in court on behalf of Focal Customers who have received
     annoying calls. AACB will build case for and establish trap for twenty-one
     (21) days. Focal shall contact the AACB (21) days. Focal shall contact the
     AACB to renew the trap beyond twenty-one (21) days. 

                             Sch. 10.12.6 - 1
<PAGE>
 
          3.2.4. The AACB shall provide to Focal a toll free number which will
     be accessible daily Monday through Friday from 8:00 a.m. - 5:00 p.m.

          3.2.5. For non-emergency (not life threatening) situations, Focal
     shall advise its Customer to contact its local Law Enforcement Agency and
     to provide Focal with required information to initiate a trap or call
     trace. Focal will contact AACB during standard operating hours to establish
     a case. For emergency (life threatening) situations, Focal shall inform its
     Customer to contact its local Law Enforcement Agency and this Agency will
     contact Ameritech to initiate a trap or call trace.

          3.2.6. Additionally, for emergency situations, Ameritech corporate
     security will provide Focal representatives with an emergency security
     contact number.

          3.2.7. Focal's Customer must contact Focal with the dates and times of
     the unwanted calls. Focal shall fax the dates and times of the unwanted
     calls to the Annoyance Call Bureau.

          3.2.8. At the end of the tracing investigation (twenty-one (21)-day
     period), Ameritech Annoyance Call Bureau shall send written confirmation to
     Focal informing Focal of the disposition of the case (i.e., successful or
                                                           ---- 
     non-successful). All evidence obtained on a successful case will be 
     forwarded to the local law enforcement agency that Focal provided to the 
     AACB. Focal shall inform its Customer of the results of the investigation.
      
          3.2.9. If Focal Customers call Ameritech to initiate an annoying call
     report, report, Ameritech shall advise the person receiving the annoying or
     harassing to call Focal.     

4.0  WIRE INTERCEPT.

     4.1. Definition - Requests from law enforcement agencies to conduct a form
of electronic or mechanical eavesdropping where, upon court order, law
enforcement officials surreptitiously monitor phone calls (e.g. conversations or
                                                           ----
data) of Focal Customers.

     4.2. Operational Interface Requirements - The Law Enforcement Agency local
police department or government organization) shall serve Ameritech with a court
order, authorizing Ameritech to conduct a wire intercept on the Focal Customer
line.

5.0  PEN REGISTER (DIAL NUMBER RECORDER).

     5.1. Definition - Requests from law enforcement agencies to conduct a
"form" of identifying calls dialed by Focal Customers in local Exchange Areas. A
pen register is a mechanical device that records the numbers dialed or pulsed on
a telephone by monitoring the electrical impulses caused when the dial on the
telephone is released. A pen register does not overhear oral communications and
does not indicate whether calls are actually completed; thus, there is no
recording or monitoring of the conversations.

                             Sch. 10.12.6 - 2
<PAGE>
 
     5.2. Operational Interface Requirements - See Wire Intercept Section 4.1.

6.0 TRACE.

     6.1. Definition - A form of electronic identification of calling numbers,
where, upon consent from the Focal Customer (via Focal) or court order, law
enforcement officials request a record of calling numbers to the premises of the
Focal Customer.

     6.2. Central Office Features - Call Trace is an advanced custom calling
feature which provides Focal direct line Customers the ability to activate the
feature by dialing a designated code. This will automatically trace the
telephone number of the line used for the last call received by the Customer.
The traced number will not be provided to the Customer, but will be provided to
law enforcement officials.

7.0  SUBPOENA MANAGEMENT.

     7.1. Definition - The law enforcement process initiated to compel the
production of certain specific documents (e.g., Customer information, name,
                                          ----
address, service type, call usage records, etc.) relevant to a legal proceeding,
are made and make them readily retrievable by local police departments,
government organizations, and attorneys. Other legal demands require the
capability to honor other legal process demands (e.g., establishment of dialed
                                                 ---- 
number recorders, wire intercepts, & trace services, etc.)

     7.2. Operational Interface Requirements - The law enforcement agency (e.g.,
                                                                           ----
local police department, government organization, or attorney) shall serve
Ameritech an original subpoena naming Ameritech in its court document for
requests for Customer information (see above definition). Ameritech shall
forward call trace information to the law enforcement agency for inquiries
regarding Focal Customers. If the law enforcement agency serves Focal the
original subpoena, Focal shall forward a copy of the original subpoena to
Ameritech and advise the law enforcement agency to re-send an original subpoena
naming Ameritech in its court document. Ameritech shall notify Focal of the
resolution of the investigation. However, Ameritech shall only provide the
results of the investigation to the proper law enforcement agency.
                      
     7.3. Operations Interface Requirements for calls originating from a long
distance carrier, computer, fax machine, pay phones, and telemarketing calls to
Focal's Customers are pending further discussions with Ameritech.

                             Sch. 10.12.6 - 3
<PAGE>
 
                                SCHEDULE 10.13

                         RESALE MAINTENANCE PROCEDURES

     By the end of Contract Month 1, /23/ the Implementation Team shall agree
                                      --
upon the processes to be used by the Parties for maintenance of Resale Services.
These processes will address the implementation of the requirements of this
SCHEDULE 10.13.
- --------------

     1.   Ameritech shall provide repair, maintenance, and testing, for all
Resale Services in accordance with the terms and conditions of this SCHEDULE
                                                                    --------
10.13.
- -----

     2.   Ameritech technicians shall provide repair service that is at least
equal in quality to that provided to Ameritech Customers; trouble calls from
Focal Customers shall receive response time priority that is at parity to that
of Ameritech Customers and shall be based on trouble severity, regardless of
whether the Customer is an Focal Customer or an Ameritech Customer.

     3.   Ameritech shall provide Focal with the same scheduled and non-
scheduled maintenance, including required and recommended maintenance intervals
and procedures, for all Resale Services provided to Focal under this Schedule
that it currently provides for the maintenance of its own network. Ameritech
shall provide Focal notice of any scheduled maintenance activity which may
impact Focal's Customers on the same basis it provides such notice to its
subsidiaries, Affiliates, other resellers and its retail Customers. Scheduled
maintenance shall include such activities as switch software retrofits, power
tests, major equipment replacements, and cable rolls.

     4.   Ameritech shall provide notice of non-scheduled maintenance activity
that may impact Focal Customers. Ameritech shall provide maintenance as promptly
as possible to maintain or restore service and shall advise Focal promptly of
any such actions it takes.

     5.   If service is provided to Focal Customers before an EI is established
between Focal and Ameritech, Focal will transmit repair calls to Ameritech
repair bureau by telephone.

     6.   Ameritech repair bureau, including the EI to be established pursuant
to the Implementation Plan, shall be on-line and operational twenty-four (24)
hours per day, seven (7) days per week except when preventative maintenance and
software revisions require an out-of-service condition. Ameritech will provide
Focal a twenty-four (24) hour advanced notification of such out-of-service
conditions.



__________________________

/23/   Since the terms of this Agreement are the result of Focal's adoption
 --
       under Section 252(i) of the Act of the AT&T Agreement, the Parties agree
       that the term "Contract Month 1", for purposes of this SCHEDULE 10.13,
                                                              --------------
       shall expire on February 28, 1999.

                              Sch. 10.13 - 1
<PAGE>
 
     7.   Ameritech shall provide progress reports and status-of-repair efforts
to Focal upon request, and at a frequency interval to be determined by Focal.
Ameritech shall inform Focal of restoration of Resale Service after an outage
has occurred.

     8.   Maintenance charges for premises visits by Ameritech technicians shall
be billed by Focal to its Customer, and not by Ameritech. The Ameritech
technician shall, however, present the Customer with unbranded form detailing
the time spent, the materials used, and an indication that the trouble has
either been resolved or that additional work will be necessary, in which case
the Ameritech technician shall make an additional appointment with the Customer.
The Ameritech technician shall obtain the Customer's signature when available
upon said form, and then use the signed form to input maintenance charges into
Ameritech's repair and maintenance database.

     9.   Dispatching of Ameritech technicians to Focal Customer premises shall
be accomplished by Ameritech pursuant to a request received from Focal. The EI
established between the Parties shall have the capability of allowing Focal to
receive trouble reports, analyze and sectionalize the trouble, determine whether
it is necessary to dispatch a service technician to the Customer's premises, and
verify any actual work completed on the Customer's premises.

Critical or Expedited Troubles.
- -------------------------------

     Upon receiving a referred trouble from Focal, the Ameritech technician will
offer a dispatch appointment and quoted repair time dependent upon Ameritech's
force-to-load condition. Ameritech's maintenance administrators will override
this standard procedure on a non-discriminatory basis, using the same criteria
as Ameritech uses to expedite intervals for itself and its subsidiaries,
Affiliates and retail Customers. If Ameritech will be unable to meet an Focal
expedited request, Ameritech will notify Focal and Focal will have the option to
implement the escalation process described in the Implementation Plan.





                              Sch. 10.13 - 2
<PAGE>
 
Disaster Recovery

The Implementation Plan will establish a process for disaster recovery that
addresses the following:

Events affecting Ameritech's network, work centers and operational support
systems;

Establishing and maintaining a single point of contact responsible for disaster
recovery activation, statusing and problem resolution during the course of a
disaster and restoration;

Procedures for notifying Focal of problems, initiating restoration plans and
advising Focal of the status of resolution;

Definition of a disaster; and

Equal priority, as between Focal Customers and Ameritech Customers, for
restoration efforts, consistent with FCC Service Restoration guidelines,
including, without limitation, deployment of repair personnel, and access to
spare parts and components.

                              Sch. 10.13 - 3
<PAGE>
 
                               SCHEDULE 10.13.2

           SERVICE ORDERING AND PROVISIONING INTERFACE FUNCTIONALITY

Electronic interfaces will provide Focal with the ability to:

     a)   Obtain, during sales discussions with a Customer, access to the
          following Ameritech Customer service record data in a manner which is
          transparent to the Customer:

          .   Billing, telephone number/name/address
          .   Service Location Address
          .   Working telephone number(s) on the account
          .   Existing service and features
          .   Blocking
          .   CLASS Features
          .   Telephone Assistance Programs, Telephone Relay Service and similar
              services indicator 
          .   Special Exemption Status indicator
          .   Directory Listing Information
          .   Information necessary to identify the IntraLATA toll provider and
              InterLATA provider, as applicable.

     b)   Obtain information on all features and services available;

     c)   Enter the Focal Customer order for all desired features and services;

     d)   Assign a telephone number (if the Focal Customer does not have one
          assigned);

     e)   Establish the appropriate directory listing;

     f)   Determine if a service call is needed to install the line or service;

     g)   Schedule dispatch and installation, if applicable;

     h)   Provide installation dates to Customer;

     i)   Order local intraLATA toll service and enter Focal Customer's choice
          of primary interexchange carrier on a single, unified order; and

     J)   Suspend, terminate or restore service to an Focal Customer.

Ameritech will support four (4) transaction types; Assume; Change; New; and
Delete, as described in Ameritech's Electronic Service Guide, which is based on
TCIF Customer Service, Issue 5.



                             Sch. 10.13.2 - 1
<PAGE>
 
Notwithstanding the foregoing, Focal shall be entitled to place orders to
transfer a Customer to Focal without identifying the specific features and
services being subscribed by such Customer at the time of the request 
("MIGRATION-AS-IS"). Furthermore, if a Customer requests changes to its features
and/or such service at the time of transfer, as part of a request for Migration-
As-Is, Focal need only specify the features and/or services which are to change.
However, unless agreed to by Ameritech, Migration-As-Is will not include any
service subscribed which is not a Telecommunications Service.
 
Critical or expedited orders:

Focal may request that the standard interval for provisioning will be expedited
if Ameritech's standard intervals do not meet the Focal Customer's requested due
date. Orders will be expedited by Ameritech on the same basis as it expedites
orders for itself and its subsidiaries, Affiliates and retail Customers. If
Ameritech will be unable to meet an Focal expedite request, Ameritech will
notify Focal and Focal shall have the option to implement the escalation process
to be defined in the Implementation Plan.





                               Sch. 10.13.2 - 2
<PAGE>
 
                                SCHEDULE 12.9.1

                    PHYSICAL COLLOCATION SPACE RESERVATION

     Space for Physical Collocation may be reserved on the following basis:

     1.   Focal may reserve additional space in an Ameritech Central Office in
which it has (or is ordering) for Physical Collocation for permitted
telecommunications-related equipment.

     2.   A reservation may be maintained only by the payment of a non-recurring
charge to defray the administrative costs of the reservation system
("RESERVATION CHARGE").
    
    3.    The reservation can be made for an amount of space no greater than the
amount of active Physical Collocation space being utilized (or ordered) for
Interconnection with and/or access to the Network Elements of Ameritech by Focal
in the particular Central Office.

    4.    The reservation takes a priority based on the time at which it is
made.

    5.    In the case of an order for Physical Collocation in an office in which
all the unoccupied space is covered by reservations, all reservations will be
prioritized. The holder(s) of the lowest priority reservation(s) which, when
considering all higher priority reservations, still represent(s) available space
sufficient to fill the order for Physical Collocation ("OPTION PARTY") will be
given the option of "enforcing" or relinquishing its (their) reservation(s).

          In this case, an Option Party may enforce its reservation by payment
of the recurring Physical Collocation floor space charge otherwise applicable to
the reservation space (in lieu of the nonrecurring Reservation Charge). The
reservation will be maintained until the Physical Collocation arrangement in
that office is terminated or the reservation is terminated, whichever comes
first. A new reservation may be activated by payment of the Reservation Charge,
but it will take a new priority based on the time of reactivation. If an Option
Party decides to enforce its reservation in this manner, the holder(s) of the
reservation(s) with the next higher priority will be given the option of
enforcing or relinquishing its (their) reservation(s).

    If an Option Party declines to enforce its reservation as indicated above,
the reservation is relinquished. A new reservation may be activated by payment
of the Reservation Charge, but it will take a new priority based on the time of
reactivation.

     6.   The holder of a valid reservation may place an order for Physical
Collocation for the reserved space at any time. If there is sufficient
unoccupied space to accommodate the order after subtracting space covered by
reservations of higher priority, the order will be processed. If there is
insufficient space to accommodate the order after subtracting space covered by
reservations of higher priority and which have been enforced, the holder may
maintain its reservation as set forth in Section 5 above.

                              Sch. 12.9.1 - 1
<PAGE>
 
    7.  In a Central Office, Ameritech may reserve space on the following
        conditions.
    
    .   The amount of space must be the least amount of space reasonably
        necessary for the provision of a communications-related service --
        including Interconnection and the provision of unbundled Network
        Elements. Except for space reserved for switch (including Tandem
        Switches and STPs) conversion and growth and for augmentation and
        conversion of mechanical and electrical support systems and building
        infrastructure, the reserved space must reasonably be anticipated to be
        used in three (3) years.
    
    .   The total amount of space reserved cannot exceed the amount of space
        Ameritech is currently using in the Central Office.
    
    .   Ameritech will impute an amount equal to the reservation charge to the
        appropriate operations for which the space is reserved.

    8.  Ameritech shall enforce its reservation in the same manner in which
Focal and other collocating Telecommunicating Carriers shall be required to
enforce its reservations. In that case, Ameritech will impute the floor space
charge to the operations for which the space is reserved.

                                Sch. 12.9.1 - 2
<PAGE>
 
                                SCHEDULE 12.9.3

                         COLLOCATION CAPACITY PLANNING

    By the end of Contract Month 3, /24/ Focal and Ameritech shall jointly
                                     --
develop a planning process for meeting Focal's space and intraoffice facility
requirements which shall include the procedures to be followed for the Focal
quarterly forecast of anticipated additional power requirements.


__________________

/24/  Since the terms of this Agreement are the result of Focal's adoption under
 --                                                                            
      Section 252(i) of the Act of the AT&T Agreement, the Parties agree that
      the term "Contract Month 3", for purposes of this SCHEDULE 12.9.3, shall
                                                        ---------------
      expire on April 30, 1999.

                                Sch. 12.9.3 - 1
<PAGE>
 
                                SCHEDULE 12.12

                         DELIVERY OF COLLOCATED SPACE

1.0 DELIVERY OF PHYSICAL COLLOCATION SPACE

    1.1 Upon receiving the written notification of the availability of
Collocation space from Ameritech, Focal shall send written verification that it
still requires each Collocation space requested on Focal's application for which
space is available. This written notification is Focal's firm order for service
for each Collocation space requested. Subject to SECTION 1.3 below, Focal's
                                                 -----------               
written notification shall be accompanied by Focal's payment of forty percent
(40%) of all applicable Central Office Build Out ("COBO") fees (the "INITIAL
COBO PAYMENT"). COBO modifications and additions to space described in the
proposal will not begin until the Initial COBO Payment has been paid. Delayed
payment of the Initial COBO Payment may delay the actual service date.

    1.2 So long as Focal has a satisfactory credit rating with Ameritech for the
twelve (12) month period preceding the date of Focal's request for Collocation
pursuant to SECTION 12.12, Focal shall pay the COBO charges as follows:
            -------------

    Initial COBO Payment:                              40% of COBO charges 
                                                  
    Delivery by Ameritech of confirmation         
    that construction of space is fifty percent   
    (50%) complete:                                    40% of COBO charges 
                                                  
    Completion of space conditioning:                  20% of COBO charges 

If Focal's credit rating is not satisfactory within the aforementioned period,
Focal shall pay the COBO charges in accordance with the provisions of
Ameritech's applicable tariff.

    1.3 If Focal's credit rating is not satisfactory within the aforementioned
period, Focal shall pay the COBO charges in accordance with the provisions of
Ameritech's applicable tariff.

2.0 ADDITIONAL RULES AND REGULATIONS APPLICABLE TO PHYSICAL COLLOCATION SPACE

    Physical Collocation will be provided subject to the following provisions:

    2.1 Focal will be responsible for any extraordinary costs incurred by
Ameritech to prepare the Collocation space for the installation of Focal's
equipment and for extraordinary costs to maintain the Collocation space for
Focal's equipment on a going-forward basis. Extraordinary costs may include
costs for such items as asbestos removal, fire suppression system or
containment, modifications or expansion of cable entry facility, increasing the
DC power system infrastructure capacity, increasing the capacity of the standby
AC system or the existing commercial power facility, conversion of
non-Collocation space, compliance with federal and state requirements or other
modifications required by local ordinances. Ameritech will charge for these
costs on a time-sensitive or time-and-materials basis.

                                Sch. 12.12 - 1
<PAGE>
 
An estimate of such costs plus contribution will be provided to Focal prior to
commencing such work. Extraordinary costs will only be billed to Focal if such
costs have been authorized by Focal. Ameritech must advise Focal if
extraordinary costs will be incurred within ten (10) Business Days from the
initial walkthrough. Otherwise, Focal will not be responsible for such costs.
Extraordinary costs do not include costs associated with maintenance and upkeep
of the building.

    At the initial walkthrough referred to in SECTION 12.12.2(b), Ameritech
                                              ------------------
shall provide to Focal a written proposal which covers Focal's requirements for
the space and details the associated requirements and the applicable charges
required to meet Focal's specific request and the expected service date. Focal
shall acknowledge acceptance of the charges in the written proposal by signing
it and returning a copy to Ameritech. Upon receipt of Focal's signed proposal,
Ameritech will begin the work and charge Focal for the actual time and material
needed to complete the modifications plus a reasonable contribution. In no case
will actual charges exceed those estimated by more than ten percent (10%).

    2.2 Focal will be responsible for notifying Ameritech of any significant
outages of Focal's equipment which could impact any of the services offered by
Ameritech, and provide estimated clearing time for restoration.

    2.3 Focal is responsible for coordinating with Ameritech to ensure that
services are installed in accordance with the service request.

    2.4 Focal is responsible for testing, if necessary, with Ameritech to
identify and clear a trouble when the trouble has been sectionalized (isolated)
to an Focal-provided service.

    2.5 Before beginning delivery, installation, replacement or removal work
for equipment and/or facilities located within the Collocation space, Focal
shall obtain Ameritech's written approval of Focal's proposed scheduling of the
work in order to coordinate use of temporary staging areas and other building
facilities. Ameritech may request additional information before granting
approval and may require scheduling changes. Focal must submit written plans for
equipment to be installed in the Collocation space prior to commencing
installation.

    2.6 Ameritech has the right to inspect Focal's completed installation of
equipment and facilities and to make subsequent and periodic inspections of the
customer's equipment and facilities occupying a Collocation space and associated
entrance conduit and riser space. If Focal is found to be in non-compliance with
the terms and conditions of this Schedule, Focal must modify its installation
to achieve compliance. Ameritech will notify Focal in advance of such
inspections, and Focal shall have the right to be present at the time of the
inspection.

3.0 DELIVERY OF VIRTUAL COLLOCATION SPACE

    3.1 Ameritech shall allow periodic inspections of Virtual Collocation space
where Focal equipment is located.

                                Sch. 12.12 - 2
<PAGE>
 
     3.2 Ameritech shall ensure that all applicable alarm systems (e.g., power)
                                                                   ----
that support Focal equipment are operational and the supporting databases are
accurate so that equipment that is in alarm will be properly identified.

     3.3 See Tariff F.C.C. No. 2, Section 16.3.

                                Sch. 12.12 - 3
<PAGE>
 
                                SCHEDULE 12.15

                              COMMON REQUIREMENTS

     The following requirements are applicable to both Physical and Virtual 
Collocation:

     1.   Ameritech shall provide to Focal any intraoffice facilities that Focal
requests and that Ameritech provides by tariff or contract to any carrier.

     2.   Ameritech shall allow for a Fiber Meet arrangement between the 
Parties' networks and facilities at the DS0, DS1, DS3, OC3, OC12 and OC48 rates 
pursuant to mutual agreement of the Parties.

     3.   Focal may provide basic telephone service with a connection jack for 
the Collocated space.

     4.   Ameritech shall provide adequate lighting, ventilation, power, heat, 
air conditioning, and other environmental conditions for Focal's space and 
equipment. These environmental conditions shall comply with Bellcore Network 
Equipment-Building System (NEBS) standards TR-EOP-000063 or other standards upon
which the Parties may mutually agree.

     5.   Ameritech shall provide access, where available, to eyewash stations, 
shower stations, bathrooms, and drinking water within the Collocated facility on
a twenty-four (24) hours per day, seven (7) days per week basis for Focal 
personnel and its designated agents.

     6.   Ameritech shall provide all ingress and egress of fiber cabling to 
Focal Collocated spaces in compliance with Focal's request for cable diversity. 
The specific level of diversity required for each site or Network Element will 
be provided in the request for Collocation. Focal will pay any additional costs 
incurred by Ameritech to meet any special diversity requirements of Focal which 
are beyond those normally provided by Ameritech.

     7.   Ameritech shall provide Focal with written notice five (5) Business 
Days prior to those instances where Ameritech or its subcontractors may be 
performing nonemergency work that may affect the Collocated space occupied by 
Focal or the AC and DC power plants that support Focal equipment. Ameritech will
inform Focal by telephone or any emergency-related activity that Ameritech or 
its subcontractors may be performing that may affect the Collocated space 
occupied by Focal or the AC and DC power plants that support Focal equipment. 
Notification of any emergency-related activity shall be made as soon as 
practicable after Ameritech learns that such emergency activity is necessary but
in no event longer than thirty (30) minutes after such time. By the end of
Contract Month 3/25/ the Implementation Team will agree upon the process for
                 --
the notification required by this Section (the "EMERGENCY NOTIFICATION 
PROCESS"). To the extent that the Emergency Notification Process requires 
Ameritech to incur additional costs, Focal shall reimburse Ameritech for such 
costs.

__________________

/25/     Since the terms of this Agreement are the result of Focal's adoption
 --
         under Section 252(i) of the Act of the AT&T Agreement, the Parties
         agree that the term "Contract Month 3", for purposes of this SECTION 7
                                                                      ---------
         OF SCHEDULE 12.15, shall expire on April 30, 1999.
         -----------------

                                Sch. 12.15 - 1
<PAGE>
 
     8. Focal shall not be required by Ameritech to relocate its equipment
during the Initial Term or any Renewal Term. If Focal, at Ameritech's request,
agrees to relocate its equipment, then Ameritech shall reimburse Focal for any
and all costs reasonably associated with such relocation.

     9. Should Ameritech sell or lease a Central Office or any portion thereof
to a third person during the Initial Term or any Renewal Term, Ameritech shall
require such third person to comply fully with the applicable terms and
conditions of this Agreement as they relate to such third person.

    10. Power as referenced in this SCHEDULE 12.15 refers to any electrical
                                    ---------------                        
power source supplied by Ameritech for Focal equipment. It includes all
superstructure, infrastructure, and overhead facilities, including cable, cable
racks and bus bars. Ameritech will supply power to support Focal equipment at
equipment specific DC and AC voltages as mutually agreed upon by the Parties.
Ameritech shall supply power to Focal at parity with that provided by Ameritech
to itself or to any third person. If Ameritech performance, availability, or
restoration falls below industry standards, Ameritech shall bring itself into
compliance with such industry standards as soon as technologically feasible.

    11. Subject to space limitations and Focal's compliance with the applicable
request process and payment requirements of this Agreement, Ameritech shall
provide power to meet Focal's reasonable needs for placement of equipment,
Interconnection, or provision of service.

    12. Both Focal's power equipment and Ameritech power equipment supporting
Focal's equipment shall comply with all applicable state and industry standards
(e.g., Bellcore, NEBS and IEEE) or manufacturer's equipment power requirement
 ----
specifications for equipment installation, cabling practices, and physical
equipment layout.

    13. Ameritech will provide Focal with written notification within ten (10)
Business Days of any scheduled AC or DC power work or related activity in the
collocated facility that poses a reasonable risk of cause an outage or any type
of power disruption to Focal equipment located in the Ameritech facility.
Ameritech shall provide Focal prompt notification by telephone of any
emergency power activity.

    14. Power plant alarms shall adhere to Bellcore Network Equipment-Building
System (NEBS) standards TR-EOP-000063.

    15. Cabling shall adhere to Bellcore Network Equipment-Building System
(NEBS) standards TR-EOP-000063.

    16. Ameritech shall provide Lock Out Tag Out and other electrical safety
procedures and devices in accordance with OSHA or industry guidelines.

    17. Ameritech shall within ten (10) Business Days after the initial
walkthrough provide Focal with a copy of any existing drawings showing Focal's
proposed Collocation space and any related Ameritech facilities, and provide
information relating to measurements for necessary Focal cabling which are not
obtainable from the drawings. Any copies of drawings shall be redacted so as not
to provide proprietary information of other carriers. So long as Ameritech
charges other

                                Sch. 12.15 - 2
<PAGE>
 
Telecommunications Carriers for the foregoing drawings and information, Focal
shall reimburse Ameritech for the costs, if any, incurred by Ameritech to
provide Focal with the foregoing drawings and information.

                                Sch. 12.15 - 3
<PAGE>
 
                                SCHEDULE 12.16

          ADDITIONAL REQUIREMENTS APPLICABLE TO PHYSICAL COLLOCATION

    The following additional requirements shall be applicable to Physical
Collocation only:

    1. Subject to space limitations and Focal's compliance with the applicable
request process and payment requirements for the space, Ameritech shall provide
space, as requested by Focal, to meet Focal's needs for placement of equipment
necessary for Interconnection and access to Network Elements.

    2. Ameritech shall allow requests for contiguous space in increments of 100
ft /2/ if the space is not subject to outstanding requests by other
Telecommunications Carriers.

    3. Other than reasonable security restrictions, Ameritech shall place no
restriction on access to the Focal Collocated space by Focal's employees and
designated agents. Such space shall be available to Focal designated agents
twenty-four (24) hours per day each day of the week. In no case should any
reasonable security restrictions be more restrictive than those Ameritech places
on its own personnel or independent contractors.

    4. For each building in which Collocated space is provided and upon request
by Focal for that building, Ameritech will, at its option, either certify that
the building complies with all applicable environmental, health and safety
regulations or complete an Environmental, Health & Safety Questionnaire provided
by Focal. Focal may provide this questionnaire with its request for Collocation
and Ameritech shall return it or the applicable certification to Focal within
ten (10) Business Days after Ameritech's receipt thereof.

    5. Ameritech shall permit Focal to install, on equipment node enclosures, an
intrusion alarm that can be remotely monitored by Focal's work center,
provided, however, that no such Focal-installed equipment shall interfere with
- -----------------
the existing use of the Central Office.

    6. Ameritech shall construct the collocated space in compliance with Focal's
request for Collocation for cable holes, ground bars, doors, and convenience
outlets as such are requested by Focal at prices to be determined.

    7. Focal shall not require advance approval from Ameritech to make
improvements or alterations to the Collocated equipment configuration that are
not substantial and do not require additional power.

    8. Central Office power supplied by Ameritech into the Focal equipment area
shall be supplied in the form of fused power feeds from Ameritech's main power
distribution board to Focal's BDFB located in the designated Focal equipment
area. The power feeders (cables) shall efficiently and

                                Sch. 12.16 - 1
<PAGE>
 
economically support the requested quantity and capacity of Focal equipment.
The termination location shall be as mutually agreed upon by the Parties.

    9.  Ameritech power equipment supporting Focal's equipment shall:

    (a) Provide appropriate Central Office ground, connected to a ground
        electrode located within the Focal collocated space, at a level above
        the top of Focal's equipment plus or minus two (2) feet to the left or
        right of Focal's final request; and

    (b) Provide feeder capacity and quantity to support the ultimate equipment
        layout for Focal equipment upon completion of the equipment node
        construction in accordance with Focal's request for Collocation.

    10. Ameritech shall within ten (10) Business Days after the initial
walkthrough provide Focal with (i) documentation submitted to and received from
contractors for any work being done on behalf of Focal that will be billed as
extraordinary expenses; and (ii) a parallel installation sequence.

    11. Ameritech shall secure external access to the Physical Collocation space
in its Premises in the same or equivalent manner that Ameritech secures external
access to spaces that house Ameritech's equipment.

    12. Ameritech shall within (30) days of the Effective Date provide to Focal
(i) work restriction guidelines related to any restrictions on the manner in
which an Focal contractor can perform work on Ameritech's Premises and (ii) a
list of Ameritech technical guidelines applicable to the collocation of
equipment in Ameritech's Premises. Focal acknowledges that it is responsible to
order such technical guidelines at its cost and expense. Ameritech will notify
Focal in a timely manner of any changes to such work restriction and technical
guidelines.

                                Sch. 12.16 - 2
<PAGE>
 
                                SCHEDULE 16.10

                            3D AND CONDO AGREEMENTS


None.





                                Sch. 16.10 - 1
<PAGE>
 
                                SCHEDULE 30.19

                           PRE EXISTING ARRANGEMENTS


None.




                                Sch. 30.19 - 1
<PAGE>
 
                        PRICING SCHEDULE -- MICHIGAN/1/


               ITEM I -- EMERGENCY NUMBER SERVICE ACCESS (ENSA) 

See Exhibit PS-I 


                      ITEM II -- RECIPROCAL COMPENSATION 

A. End Office Local Termination                   $.004053 per minute 
                                                                    
B. Tandem Switching                               $.000698 per minute 
                                                                    
C. Tandem Transport Termination                   $.000260 per minute 
                                                                    
D. Tandem Transport Facility Mileage              $.000006 per minute, per mile 


                   ITEM III -- INFORMATION SERVICES TRAFFIC 

Information Services Billing and Collection:      $0.03 per message 


                         ITEM IV -- BLV/BLVI TRAFFIC 

A. Busy Line Verification (BLV):                  $0.613 per use
                                                                
B. Busy Line Verification Interrupt (BLVI):       $0.753 per use 
   (in addition to BLV charge)

                                   
______________

/1/  Certain of the rates, charges and prices contained in this Pricing Schedule
     have been established by the Commission pursuant to its July 14, 1997
     and January 28, 1998 orders (collectively, the "Rate Order") in MPSC Case
     No. U-11280 (the "Permanent Rate Docket"). If the Commission determines
     that the rates, charges and prices set forth herein are inconsistent with
     the Commission's decision in the Permanent Rate Docket, either Party shall,
     upon written notice to the other Party, have the right to include or
     substitute rates, charges and prices that confirm to the Permanent Rate
     Docket. Notwithstanding anything to the contrary in this Agreement,
     including Section 29.3. if the Commission, a court or other tribunal
               -------------
     of competent jurisdiction issues an order or decision modifying the Rate
     Order (a "Modifying Order"), either Party shall, upon written notice to the
     other Party, have the right to require that this Agreement be amended to
     reflect such Modifying Order and such amended or new rates, charges or
     prices shall be effective as if such rates, charges and prices were
     originally established in the applicable Rate Order.

                                     PS-1
<PAGE>
 
                     ITEM V -- UNBUNDLED NETWORK ELEMENTS

A.  Unbundled Loop Rates
 
    1.  Recurring Rates
 

<TABLE>
<CAPTION>
                                                     Monthly Rates 
                                                     Access Area/2/
                                                                 -
                                                   A       B       C
                                                 ------  ------  ------ 
        <S>                                      <C>     <C>     <C>  
        2-Wire Analog

            Basic                                $ 9.43  $12.02  $14.86

            Ground Start                         $10.17  $13.21  $15.89

            Electronic Key Line                  $14.63  $20.40  $22.08

        4-Wire Analg                             $22.46  $30.05  $34.90
                                             
        Digital

            ISDN                                 $11.22  $14.92  $17.35
                                                         
            4-wire 64 Kbps                       $60.29  $60.24  $60.06
                                                         
            4-wire 1.544 Mbps                    $92.88  $71.06  $64.58
                                                                         
            2-wire ADSL/HDSL                                            
            Compatible                           $ 9.43  $12.02  $14.86  
                                                                         
            4-wire HDSL Compatible               $22.46  $30.05  $34.90  

        Cross-Connect Charge (additional,
        per cross-connect):

            2-wire                               $ 0.17
                                                      
            4-wire                               $ 0.34
                                                      
            6-wire                               $ 0.51
                                                      
            8-wire                               $ 0.68
                                                      
            DS1                                  $ 0.46
</TABLE> 

                           
_____________
                                             
/2/  "Access Area" is as defined in Ameritech's applicable tariffs for business
 -                                                                            
     and residential Exchange Line Services.

                                     PS-2
<PAGE>
 
<TABLE>
<CAPTION>
                                                 A          B            C 
                                             ---------  --------      --------
 <S>                                         <C>        <C>           <C> 
           DS3                                 $ 0.84   
                                                        
        Service Coordination Fee,              $ 0.84   
        Per Carrier Bill, per Switch                    
                                               
    2.  Non-Recurring Rates                    
                                               
        Service Order -- Establish/Change:   
        (Business or Residence)                $ 6.42/3/   
                                                         
        Line Connection: (Business or          
        Resident)                              $18.60/4/   
                                             
        Record Change                          $ 6.42
                                                    
        Provisioning Change                    $ 6.42

 B. NID/5/ No Charge
        -           


 C. Switching

    1.  Unbundled Local Switching

                                                        Non-Recurring   Monthly 
                                                        -------------   -------

        (a)  Custom Routing
             - per new LCC, per switch                     $114.68           --
                                                                               
        (b)  ULS Ports                                     
                                                           
             - Basic Line Port, per port                   $ 26.83        $2.27
                                                                                
             - Ground Start Line Port, per port            $ 26.83        $2.77
</TABLE> 
                                                 

_____________ 

/3/  The Service Order Charge is a per occasion charge applicable to any number
 -
     of Loops ordered for the same location and same Customer account.

/4/  The Line Connection Charge applies to each Loop.
 -

/5/  Access to Network Interface Device for Accessing Customer Premises Wiring
 -
     (Inside Wire).

                                     PS-3
<PAGE>
 
<TABLE>
<CAPTION>
                                                   Non-Recurring     Monthly
                                                   -------------     -------
 <S>                                               <C>               <C> 
     - ISDN-Direct Port,
        per port                                      $ 26.83        $ 12.41 
        per telephone number                               --        $  0.01 
                                                                             
     - DID Trunk Port,                                                       
        per port                                      $ 26.83        $ 13.26 
        per telephone number                               --        $  0.01 
        add/rearrange each termination                $ 12.17             -- 
                                                                             
     - ISDN Prime Trunk Port,                                                
        per port                                      $309.24        $159.23 
        per telephone number                               --        $  0.01 
        add/rearrange channels                        $ 12.17            --  
                                                                             
        - Digital Trunking Trunk Port,                $309.24        $114.75 
        per port                                                             
                                                                             
        - Custom Routing Port,                                               
        per port                                      $309.24             -- 
        per individual trunk termination                   --        $ 99.83 
                                                                             
     - Centrex Basic Line Port, per port              $ 26.83        $  2.27 
                                                                             
     - Centrex ISDN Line Port, per port               $ 26.83        $ 12.41 
                                                                             
     - Centrex EKL Line Port, per port                $ 26.83        $  2.78 
                                                                             
     - Centrex Attendant Console Line Port,                                   
        per port                                      $ 53.66        $ 74.78  
                                                                             
 (c) Centrex System Charges                                                    
                                                                               
     - System Features, per common block                   --        $354.86   
                                                                               
     - Common Block establishment, each               $189.07             --   
                                                                               
     - System features change or rearrangement,                                 
        per feature, per occasion                     $ 25.82             --    
                                                                                
     - System feature activation, per feature,                              
        per occasion                                  $105.98             --
</TABLE> 

                                     PS-4
<PAGE>
 
<TABLE>
<CAPTION> 
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C> 
   (d) Service Charges

       Service Ordering Charges

       - Initial 
         -------                                                
           Line port, per occasion                     $     6.42           --
           Trunk port, per occasion                    $   167.76           --
                                                                
       - Subsequent                                             
         ----------                                             
           per occasion                                $     6.42           --
                                                                
       -   Record Order per occasion                   $     6.65           --
                                                                
       Conversion Charge                                        
                                                                
       -   change from one type of line-port                     
           to another, per each changed                $    24.64           --

       Ameritech Cross-Connection Service, per
       carrier transport facility,
       -   2-Wire (Line port), each                            --    $    0.17 
       -   DS1 (trunk port) (each individual trunk)            --    $    0.46
 
   (e) Service Coordination Fee
       - per carrier bill, per switch.                         --    $    0.84

   (f) Subsequent Training 
       - per Company person, per hour                  $    33.41           --
                                                                   
   (g) ULS Usage                                                   
       - Billing Development                           $14,734.57           --

       - Per minute of use or fraction thereafter                    $0.003164
                                                                              
       - Daily Usage Feed per message                                $0.000789 

2. Unbundled Tandem Switching

   Tandem Trunk (DS1), including features              $   310.31    $  131.06 

   Service Order Charge                                $   167.76
                                                                
   Cross-Connect Charge, per DS1                                     $    0.46
                                                                
   Subsequent Changes                                  $    12.17           --
</TABLE> 

                                     PS-5
<PAGE>
 
                                                    Non-Recurring    Monthly
                                                    -------------    -------


                                                       Per Minute
                                                       ----------

Usage Without Tandem Trunks                             $0.000756
                            
D. Dedicated Interoffice Transmission Facility

<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
   <S>                                              <C>              <C> 
   1.  DS1 Rates
       Entrance Facility
       Per point of Termination
         Terminating Bit Rate 1.544 Mbps

       Zone 1                                                  --     $92.88
       Zone 2                                                  --     $71.06
       Zone 3                                                  --     $64.58

       Interoffice Mileage Termination     
       Per point of Termination 1.544 Mbps 
                                           
       Zone 1                                                  --     $14.66
       Zone 2                                                  --     $14.66
       Zone 3                                                  --     $14.66
                                           
       Interoffice Mileage Per Mile 1.544  
       Mbps                                
                                           
       Zone 1                                                  --     $ 1.37
       Zone 2                                                  --     $ 1.37
       Zone 3                                                  --     $ 1.37
                                           
       Optional Features and Functions Clear
       Channel Capability                  
       Per 1.544 Mbps Circuit Arrange       

       Zone 1                                           $  189.84         --
       Zone 2                                           $  189.84         --
       Zone 3                                           $  189.84         --
</TABLE> 

                                     PS-6
<PAGE>
 
                                                    Non-Recurring    Monthly
                                                    -------------    -------

       Interconnection Central Office      
       Multiplexing                        
                                           
       DS1 to Voice/Base Rate/128.0, 256.0,
       384.0 Kbps Transport                 

       Zone 1                                                 --     $334.09
       Zone 2                                                 --     $334.09
       Zone 3                                                 --     $334.09

   2.  DS3 Rates                             
       Entrance Facility, per Point of       
       Termination                           
          DS3 with Electrical Interface Per   
          Termination

       Zone 1                                                 --     $719.52 
       Zone 2                                                 --     $810.59 
       Zone 3                                                 --     $793.90
                                                                            
       Interoffice Mileage Termination                                        
       Per Point of Termination                                               
                                                                              
       Zone 1                                                 --     $144.97  
       Zone 2                                                 --     $144.97  
       Zone 3                                                 --     $144.97  
                                                                              
       Interoffice Mileage Per Mile                                            
                                                                               
       Zone 1                                                 --     $ 29.16   
       Zone 2                                                 --     $ 29.16   
       Zone 3                                                 --     $ 29.16   
                                                                               
       Optional Features and Functions                                         
                                                                              
       Interconnection - Central Office                                        
       Multiplexing, Per Arrangement

       DS3 to DS1 

       Zone 1                                                 --     $383.31
       Zone 2                                                 --     $383.31
       Zone 3                                                 --     $383.31

                                     PS-7
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C>  
3. OC-3 Rates Entrance Facility, per       
   point of termination
   Terminating Bit Rate 155.52 Mbps                                  $326.74
                                                                           
   Interoffice Mileage Termination,                                          
   per point of mileage termination                                          
   155.52 Mbps                                                       $347.19 
                                                                             
   Interoffice Mileage, per mile                                              
   155.52 Mbps                                                       $204.80  
                                                                              
   Optional Features and Functions                                             
                                                                               
   OC-3 Add/Drop Multiplexing, per                                             
   arrangement                                                       $562.48    
                                                                                
   Add/Drop Function                                                           
   Per DS3 Add or Drop                                               $126.22   
   Per DS1 Add or Drop                                               $ 38.99   
                                                                               
   1 + 1 Protection, per OC-3 Entrance                                          
   Facility                                                          $ 49.92    
                                                                                
   1 + 1 Protection with Cable                                               
   Survivability, per OC-3 Entrance                                          
   Facility                                           $1,261.80      $ 49.92 
                                                                             
   Cross-Connection of Services OC-3 to                                      
   OC-3 Cross-Connect, per circuit                                   $ 92.22 
                                                             --              
   1 + 1 Protection with Route                                                  
   Survivability                                                              
                                                    Apply 1 + 1 Protection, per 
   (1) Per OC-3 Entrance Facility                   OC-3 Entrance Facility Rates
                                                    and Charges as specified    
                                                    above plus (2) below      

   (2) Per Quarter Route Mile                                        $ 41.14  
                                                                             
4. OC-12 Rates                                                                

   Entrance Facility, per point of 
   termination, Terminating Bit 
   Rate 622.08 Mbps                                                  $530.35   
</TABLE> 

                                     PS-8
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C>  
   Interoffice Mileage Termination, 
   per point of mileage termination 
   622.08 Mbps                                                       $  589.98 
                                                                           
   Interoffice Mileage, per mile                                     
   622.08 Mbps                                                       $  371.24
                                                                            
   Optional Features and Functions                                          
                                                                            
   OC-12 Add/Drop Multiplexing, per                                         
   arrangement                                                       $  630.21
                                                                            
   Add/Drop Function                                                        
                                                                            
   Per OC-3 Add or Drop                                              $  175.82
   Per DS3 Add or Drop                                                   38.12

   Cross-Connection of Services 
   OC-12 to OC-12 Cross-Connect, 
   per circuit                                                       $  486.16
                                                                           
   1 + 1 Protection, per OC- 12                                              
   Entrance Facility                                                 $  246.97 

   1 + 1 Protection with Cable 
   Survivability, per OC-12 
   entrance facility                                    $1,261.80    $  246.97 

   1 + 1 Protection with Route                                                
   Survivability 

   (1) Per OC-12 Entrance Facility                 Apply 1 + 1 Protection, per  
                                                   OC-12 Entrance Facility Rates
                                                   and Charges as specified     
                                                   above plus (2) below         

   (2) Per Quarter Route Mile                                        $   36.97 
                                                                             
5. OC - 48 Rates                                                     
                                                                     
   Entrance Facility, per point of                                   
   termination Terminating Bit Rate                                  
   2488.32 Mbps                                                      $2,233.48
                                                                              
   Interoffice Mileage Termination, per                              
   point of mileage termination 2488.32                               
   Mbps                                                              $1,364.94
                                                                              
   Interoffice Mileage, per mile 2488.32                             
   Mbps                                                              $  239.33
</TABLE> 

                                     PS-9
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
       <S>                                          <C>              <C> 
       Optional Features and Functions

       OC-48 Add/Drop Multiplexing, per 
       arrangement (not to exceed 12 
       DS3s or equivalent)                                           $  732.90
                                                                             
       Add/Drop Function                                                      
       Per OC-12 Add or Drop                                         $  346.13
       Per OC-3 Add or Drop                                          $  159.92
       Per DS3 Add or Drop                                           $   57.27
                                                                              
       Cross-Connection of Services OC-48                                     
       to OC-48 Cross-Connect, per circuit                           $1,074.81
                                                                              
       1 + 1 Protection, per OC-48                                            
       entrance facility                                             $  930.44

       1 + 1 Protection with Cable 
       Survivability, per OC-48 entrance               $1,261.80     $  930.44
       facility

       1 + 1 Protection with Route 
       Survivability

       (1) Per OC-48 Entrance Facility             Apply 1 + 1 Protection, per 
           Channel                                 OC-48 Entrance Facility Rates
                                                   and Charges as specified    
                                                   above plus (2) below   

       (2) Per Quarter Route Mile                                    $   61.60 
</TABLE> 


<TABLE>
<CAPTION> 
                                                   Design and               
                                                 Central Office     Carrier 
                                                   Connection     Connection
                               Administration     Charge, per     Charge, per
                                Charge, per         circuit       termination
                                -----------      --------------   -----------
                                   order                                    
                                   -----                                     
<S>                            <C>               <C>              <C> 
6. Installation and
   Rearrangement
   Charges DS1
   Service 1.544 Mbps
</TABLE> 
 
                                     PS-10
<PAGE>
 
<TABLE>
<CAPTION>
                                                   Design and               
                                                 Central Office     Carrier 
                                                   Connection     Connection
                               Administration     Charge, per     Charge, per
                                Charge, per         circuit       termination
                                -----------      --------------   -----------
                                   order                                    
                                   -----                                     
          <S>                  <C>               <C>              <C> 
          Zone 1                   $169.14        $267.42            $244.02  
          Zone 2                   $169.14        $267.42            $244.02
          Zone 3                   $169.14        $267.42            $244.02

          DS3 Service 44.736
          Mbps

          Zone 1                   $128.09        $284.49            $157.75
          Zone 2                   $128.09        $284.49            $157.75
          Zone 3                   $128.09        $284.49            $157.75

          OC-3 Service
          155.52 Mbps              $ 51.93        $211.01            $414.21

          OC-12 Service
          622.08 Mbps              $ 51.93        $211.01            $414.21

          OC-48 Service
          2488.32 Mbps             $ 51.93        $211.01            $414.21
</TABLE>


E.   Shared Interoffice Transmission Facilities

     The rates, charges and prices for Shared Interoffice Transmission
     Facilities are the following elements set forth in F.C.C. Tariff No. 2
     Sections 6.1.3 and 6.9.1: (i) Tandem-Switched Termination per Access
     Minute and (ii) Tandem-Switched Facility per Access Minute per Mile. To the
     extent that Requesting Carrier also purchases Tandem Switching, Requesting
     Carrier shall compensate Ameritech for such Tandem Switching at the
     applicable rates set forth on Item V (C) (2) of the Pricing Schedule in
     addition to any applicable charges for Shared Interoffice Transmission
     Facilities.

                                     PS-11
<PAGE>
 
<TABLE>
<CAPTION>
                                                       Non-Recurring       Monthly        Usage
                                                       -------------       -------        -----
<S>                                                    <C>                 <C>            <C> 
F. Transiting (local and intraLATA toll):

   Tandem Switching per minute                                   --             --        $0.004002
   Tandem Transport per minute                                   --             --        $0.000260
   Tandem Transport Facility per minute                          --             --        $0.000084

G. Signaling Networks and Call-Related
   Databases

   1. Signaling Networks (signal Links as per
      MPSC No. 21, Part 8)

      Signal Transfer Point, per port                       $254.79        $270.11               --

      Originating Point Code, per service 
      added or changed                                      $  9.63             --               -- 
                                                          
      Global Title Address Translation, per service       
      added or changed                                      $  5.18             --               -- 
                                                          
      Signal Switching, per ISUP message                         --             --        $0.000121
                                                                                                  
      Signal Switching, per TCAP message                         --             --        $0.000103
                                                                                                  
      Signal Transport, per ISUP message                         --             --        $0.000046
                                                                                                  
      Signal Transport, per TCAP message                         --             --        $0.000031
                                                                                                  
      Signal Formulation, per ISUP message                                                $0.000699
                                                                                                  
      Signal Formulation, per TCAP message                                                $0.000417
                                                                                                  
      Signal Tandem Switching, per ISUP message                                           $0.000207


                                                                                     Per Query
                                                                                     ---------

   2. Call-Related Databases

      800 Service 

      Database Query Using Ameritech - Provided 
      Facilities

      - 80ODB Call-Routing Query                                                          $0.002837 
</TABLE> 

                                     PS-12
<PAGE>
 
                                                                      Per Query
                                                                      ---------

      - 80ODB Routing Options Query                                   $0.000930

      Local STP Database Query Utilizing Requesting
      Carrier Provided Facilities between the Requesting
      Carrier's Switch and Ameritech's STP and
      Ameritech Provided Facilities between Ameritech's
      STP and Ameritech's Regional STP

      - 80ODB Carrier-ID-Only Query                                   $0.001227 
                                   
      - 80ODB Routing Options Query                                   $0.000185
                                                                              
      Regional STP Database Query Utilizing Requesting                
      Carrier - Provided Facilities                                   
                                                                      
      - 80ODB Carrier-ID-Only Query                                   $0.001170
                                                                               
      - 80ODB Routing Options Query                                   $0.000131 

      LIDB Service
                  
      LIDB Queries 

      - LIDB Validation Query                                         $0.013817
      - LIDB Transport Query                                          $0.000069
      - LIDB to LIDB Query                                            $0.048058
                                                                              
      Query at regional STP                                                   
      - LIDB Validation Query                                         $0.013817
      - LIDB Transport Query                                          $0.000013

      Ameritech Provided Services requiring LIDB Queries 

      - LIDB Validation Query                                         $0.013817 
          - LIDB Transport Query                                      $0.000813 
          - LIDB to LIDB Query                                        $0.048803 


   3. Service Management Systems 

      Access to Databases - TBD/6/
      --------------------      - 


_________________

/6/  "TBD" means "to be determined." The rate structure set forth herein may
 -
     ultimately be modified.

                                 PS-13
<PAGE>
 
H.   Operator Services and Directory Assistance

     1. Operator Services

        Manual Call Assistance Occurrences - rates will apply based on the total
        -----------------------------------                                     
        monthly volume and a LIDB charge will apply separately to all
        occurrences requiring billing validation.

        $0.340 per occurrence

        Automated Call Assistance Occurrences - rates will apply based on the
        --------------------------------------                               
        total monthly volume, and a LIDB charge will apply separately to all
        automated occurrences.

        $0.018 per occurrence

        Branding per trunk group  --  $386.56 non-recurring charge 

     2. Directory Assistance

           Directory Assistance, rate per call $0.205

I.   Combinations of Network Elements /7/  
                                       -

J.   Rates for Maintenance. 

     1. Trip Charge -- as per Ameritech's Retail Tariff 

     2. Time Charge -- as per Ameritech's Retail Tariff 


                     ITEM VI -- WHOLESALE RESALE SERVICES

A.   See Schedule 10.1

B.   "Warm" Transfer          TBD



                            ITEM VII -- COLLOCATION

A. Physical

                                                       
______________

/7/  Charges for Combinations of Network Elements are determined based on
 -   
     charges set forth in this Pricing Schedule for individual elements as
     defined in Schedule 9.3.4. Notwithstanding anything to the contrary,
                ----------------                                         
     Ameritech is not waiving its right to amend this Agreement pursuant to
     Section 29.3.
     -------------

                                    PS-14
<PAGE>
 
<TABLE>
<CAPTION>
Description                                        Recurring   Non-Recurrin
- -----------                                        ---------   ------------ 
<S>                                                <C>         <C> 
Order Charge                                              --
   - Per ACOI Application                                 --     $   123.17

      Central Office Floor Space                                         
         - Per 100 Sq. Ft.                           $703.69             --   

      Central Office Build Out
- - Per Initial 100 Sq. Ft. of Floor Space
      Requested, Per Central Office                       --     $12,482.36
         - 50 % charge                                    --     $ 6,241.18 
         - 25 % charge                                    --     $ 3,120.59

- - Per Additional 100 Sq. Ft. of Floor Space 
Requested, Per Central Office                             --     $ 5,342.22
   - 50 % charge                                          --     $ 2,671.11
   - 25 % charge                                          --     $ 1,335.56

Cable Vault Splicing
   - Per Initial Splice                                   --     $    90.26 
   - Per Subsequent Splice                                --     $     6.61
  
Splice Testing
   - Per Initial Splice Test                              --     $    20.73 
   - Per Additional Splice Test                           --     $     1.22

Cable Pulling From Manhole to Cable Vault
   - Per First Foot                                       --     $    98.04
   - Per Additional Foot                                  --     $     0.49

Cable Pulling From Cable Vault to 
Transmission Node
   - Per First Foot                                       --     $    36.59 
   - Per Additional Foot                                  --     $     0.37

Riser Space
   - Per Foot                                        $  1.05             --

Entrance Conduit
   - Per Inner Duct, per Foot                        $  0.05             --

Power Consumption
   - Per Fuse AMP                                    $  5.73             --     

Power Delivery
   - Per Power Lead                                       --     $   751.63
</TABLE> 

                                    PS-15
<PAGE>
 
<TABLE>
<CAPTION>
     Description                                     Recurring    Non-Recurring
     -----------                                     ---------    -------------
<S>                                                  <C>          <C>   
     200 Conductor Electrical Cross-Connection
     Block
        - Per 200 Conductor Electrical Cross-          $69.78                --
        Connection Block                                    
                                                       
     Digital Cross-Connection Panel (DSX)              
        - Per DSX-3 Termination (1 DS3                 
        termination)                                   $16.61                --
        - Per DSX-1 Panel (Up to 56 DS1                     
        terminations)                                  $52.04                --

     Optical Cross-Connection Panel (OCX)
        - Per OCX Panel Segment                        $ 6.25                --
                                                           
     Space Reservation Charge                           
        - Per Reservation Request                          --         $  304.78

     Optional Features and Functions

     Transmission Node Enclosure
        - Per First 100 sq. ft. Enclosed                   --         $1,850.41 
        - Per Additional 100 sq. ft. Enclosed              --         $  730.79

     Passive Bay Termination (includes Bay and 
     Panel)                                            $ 0.58                --
        - DS1 Termination                              $ 7.32                --
        - DS3 Termination
 
     200 Conductor Electrical Termination Block
     (outside Transmission Node)
        - Per Termination Block                        $69.78                --

     Digital Timing Source
        - Per Sync Signal Provided                     $14.00                -- 

     DS1 Repeater                                      $ 6.49                --

     DS3 Repeater                                      $37.69                --

     Diverse Riser
        - Per floor traversed                              --         $  224.84

B.   Virtual
     Service Order Charge
        - Per Order                                        --         $   48.09 
</TABLE> 

                                     PS-16
<PAGE>
 
<TABLE>
<CAPTION>
Description                                          Recurring    Non-Recurring
- -----------                                          ---------    -------------
<S>                                                  <C>          <C>   
Optical Line   Entrance Facility
    - Per Foot                                        $ 0.05/8/              --
                                                             -

Riser
    - Space Per Foot                                  $ 0.24                 -- 
    - Per Fiber Termination                           $ 1.65                 --

Cable Vault Splicing
    - Per Initial Splice                                  --           $  90.26
    - Per Subsequent Splice                               --           $   6.61

Splice Testing
    - Per Initial Splice Test                             --           $  20.73
    - Per Subsequent Splice Test                          --           $   1.22 

Cable Pulling From Manhole to Cable Vault
    - Per First Foot                                      --           $  98.04 
    - Per Additional Foot                                 --           $   0.49 
                                                                               
Cable Pulling From Cable Vault to the LGX Panel                        $  36.59
    - Per First Foot                                      --           $   0.37
    - Per Additional Foot                                 --                    
                                                                              
Diverse Riser                                                                   
    - Per floor traversed                                 --           $ 224.84 

Equipment Bay
    - Per 7' Bay Installed (Ameritech
    provided/installed/pre-packaged)                  $41.17           $ 164.00

Equipment Bay
    - Per 7' Bay Installed (Requesting
    Carrier provided/installed)                       $26.33                 --/9/

Project Management Fee
    - Per Initial 7' Bay Installed on Initial or
    Subsequent Order                                      --           $1219.12

    - Per Additional 7' Bay Installed on
    Initial or Subsequent Order                           --           $ 609.56
</TABLE> 

___________________
/8/  Rates indicated do not include cable.
 -

/9/  Rates indicated do not include cable.
 -

                                     PS-17
<PAGE>
 
<TABLE>
<CAPTION>
Description                                          Recurring    Non-Recurring
- -----------                                          ---------    -------------
<S>                                                  <C>          <C>
    - Per Initial Shelf Installed 
    on Subsequent Order                                     --        $914.34
                                                                            
    - Per Additional Shelf Installed on Same                --        $548.61
    Subsequent Order                         
 
    - Per Bay Rearrangement and/or
    Miscellaneous Work                                      --        $731.47
 
Power Consumption
    - Per Fuse AMP                                      $ 5.73             --

Power Delivery
    - Per 7' Bay Installed                                  --        $751.63

200 Conductor Electrical Cross-Connection 
Block
    - Per 200 Conductor Electrical                      $69.78             -- 
    Cross-Connection Block

Digital Cross-Connection Panel (DSX) 
    - Per DSX-3 Termination (1 DS3
    termination)                                        $16.61             --

    - Per DSX-1 Panel (Up to 56 DS1 
    terminations)                                       $52.04             --

Optical Cross-Connection Panel (OCX)
    - Per OCX Panel Segment                             $ 6.25             -- 

Digital Timing Source
    - Per Timing Circuit Required                       $ 2.79             --

    Thru-Connect
    - Per DSX-1 to DSX-1                                $ 0.21        $  2.92
    - Per OCX to OCX                                    $ 1.60        $  2.92
</TABLE> 


                            ITEM VIII -- STRUCTURE

See Exhibit PS-VIII.

                                     PS-18
<PAGE>
 
                ITEM IX --- SERVICE PROVIDER NUMBER PORTABILITY

                                                      I.N.C./10/  Per Month/10/
                                                      -----  --   --------- --
  A. SPNP-Remote
     Service Ordering Charge, per occasion/11/        $ 31.05 
                                           --
     per number ported                                $ 11.20        $  2.84 
     per additional call path/12/ (1-5)               $  5.85        $  0.09
                              --
     per additional call path (6-90)                  $  5.85        $  0.34 


  B. SPNP-Direct

     Service Ordering Charge, per occasion            $ 47.56


     Service Establishment Charge
        per SPNP-Direct trunk group,
        per switch                                    $ 31.77            --- 

     SPNP-Direct Channel Termination                     
        charges, per SPNP-Direct VG
        channel termination                           $ 19.60        $ 20.05
         per SPNP-Direct DS1 
        channel termination                           $159.02        $132.16
                                                         

______________________

/10/ Rates suspended pending Commission approval of a competitively neutral cost
 --  
     recovery mechanism.
     
/11/ Service Coordination Fee Charges apply.
 --

/12/ Service Ordering charges for additional call capacity for a ported number
 --  
     are not applicable if ordered coincident with its specific ported number.
     If ordered subsequent to SPNP-Remote Service or with an unrelated ported
     number, Service Ordering charges apply per occasion.

                                     PS-19
<PAGE>
 
<TABLE> 
                                               I.N.C. /13/                 Per Month /13/
                                               -----   --                  ---------  -- 
<S>                                            <C>                         <C> 
SPNP-Direct Number Charges
     per number ported                              $ 1.83                   $.034054     

SPNP-Direct Transport Charges,/14//15/
                               --  -- 
     per SPNP-Direct VG transport              See Footnote /16/           See Footnote /16/
                                                             --                          --  
     per SPNP-Direct VG w/o transport/17/ 
                                      --
     per SPNP-Direct DS1 transport             See Footnote /18/           See Footnote /18/      
                                                             --                          --
     per SPNP-Direct DS1 w/o transport/17/
                                       --     
  
Subsequent additions, deletions or
rearrangement of SPNP-Direct trunk
terminations in addition to above
charges
     per occasion                                   $12.13
</TABLE> 

__________________

/13/   Rates suspended pending Commission approval of a competitively neutral
 --    
       cost recovery mechanism.

/14/   Service ordering charges, as shown in Item V, apply.
 --

/15/   Line connection charges, as shown in Item V, apply.
 --

/16/   Rates for unbundled PBX ground start loops apply, as specified in Item V.

/17/   Where SPNP Direct is provisioned, cross-connection charges as specified 
 --    
       in Item V apply.

/18/   SPNP Direct DS1 is provisioned at the rates and charges for DS1 service, 
 --    
       as specified in Item V.D.1 apply.

                                     PS-20

<PAGE>
 
                                 EXHIBIT PS -1

Emergency Number Service Access
(ENSA)

Description                                  Non-Recurring           Monthly
- -----------                                  -------------           -------

1. Channel Conditioning
   - Per Channel 
     - Back to Back                               $365.89            $ 32.88  
       Collocated                                 $365.89            $ 32.88
     - Direct (1st Channel) Channels              $357.39            $199.56
       2-24 (per channel)                         $357.39            $  1.88

ANI/ALI/SR and Database Management
- - Per 1,000 main stations and
  equivalent network access lines served,
  rounded up to the nearest 1,000                 $  6.81            $ 27.77

Control Office Administration
- - Per NXX                                         $122.11            $  2.15  
    
The prices for Route Diversity will be determined on a case by case basis.

The charges for Alternate Control Office Access, enabling routing of 911 calls 
across multiple selective routing areas, is in addition to all other charges,
and subject to Ameritech approval.

                                                       Nonrecurring
                                                       ------------

Alternate Control Office
- -  Per Trunk Group                                       $548.24

Address & Routing File (ARF)
- -  Per File Request                                      $ 56.50

Manual Updates
- -  Per Record, per occasion                              $  1.58


                                Exhibit PS-1-1
<PAGE>
 
                                EXHIBIT PS-VIII
                             STRUCTURE PRICING/1/
                                               -

             POLE ATTACHMENT AND CONDUIT OCCUPANCY ACCOMMODATIONS

                                             Nonrecurring Charge      Per Year
                                             ----------------------------------

Administrative Fee
- -  per request or assignment                           $200.00

Pole Attachment Fee
- -  per pole, per year for each foot of
   usable space occupied and for each power
   supply or equipment case or cabinet
   attached to a pole                                                $  1.97

Conduit Attachment Fee
- -  per foot of innerduct occupied per year                           $   .33/2/ 
                                                                             -
   
________________

/1/  The rates set forth above are currently the charges for the lowest existing
 -   contract available to an attaching party in the state of Michigan and shall
     be adjusted periodically consistent with the terms of the Agreement.

/2/  If an Attaching Party occupies an entire duct, the Attachment Fee shall be 
 -   two (2) times the rate per innerduct foot for the Attachment.

                               Exhibit PS-VIII-1
<PAGE>
 
                                EXHIBIT PS-VIII
                             STRUCTURE PRICING/3/
                                               -

A.   The following fees, rates and charges apply to Attachment to Ameritech
Structure.

     1.   Administrative Fees. Administrative Fees cover the cost of 
establishing records, databases and systems, the processing of assignment of
permits and similar administrative procedures to accommodate a Requesting
Carrier's request for Attachment. Administrative Fees are payable with
Requesting Carrier's initial request for Attachment, and for assignment of any
permit, or series of permits, to a single assignee. Administrative fees are not
refundable.

Administrative Fee - $200.00 per request of assignment.

     2.   Maps, Records and Information Charges. Maps, Records and Information 
charges cover the cost of researching and preparing records and information and 
preparing maps or drawings in order to provide access to the same to a 
Requesting Carrier. Charges for these services will be as follows:

          a. Initial Map Preparation - The full cost to Ameritech to prepare a 
             map or record for access by a Requesting Carrier.

          b. Record Searches and Information Requests - The full cost to
             Ameritech to research records and assemble information to respond
             to a Requesting Carrier's request for information and, if
             applicable, to meet with the Requesting Carrier to clarify the map,
             record or information.

Prior to initiating Initial Map Preparation or Record Searches and Information 
Requests, the Requesting Carrier shall deposit with Ameritech against the 
charges therefor Ameritech's estimated amount of charges associated with the 
requested Initial Map Preparation or Record Search and Information Request. The 
Requesting Carrier shall pay the amount by which the costs of the request 
exceeds the estimate. Ameritech will reimburse to the Requesting Carrier the 
amount by which the deposit exceeds the actual cost of the request.

     3.   Make Ready Work Charges. Make Ready Work Charges include all of 
Ameritech's costs to prepare Structure for the Attachments of the Requesting 
Carrier, including engineering, field surveys, permits, construction, 
rearrangement, replacement, inspections, administration and supervision.

___________________

/3/  The rates set forth above are currently the charges for the lowest existing
 -   contract available to an attaching party in the state of Michigan and shall
     be adjusted periodically consistent with the terms of the Agreement.

                               Exhibit PS-VIII-2
<PAGE>
 
          a.   The charges for Make Ready Work are the full cost to Ameritech to
               perform the required work.

          b.   Prior to commencing any make Ready Work by Ameritech, the
               Requesting Carrier shall deposit with Ameritech against the Make
               Ready Work Charges, Ameritech's estimated amount of the Make
               Ready Work Charges. The Requesting Carrier shall pay the amount
               by which the Make Ready Work Charges exceeds the deposit.
               Ameritech will refund to the Attaching Party the amount by which
               the deposit exceeds the Make Ready Work Charges.

          c.   For requests for access to Ameritech's Ducts, Conduit or Rights-
               of-way, the Requesting Carrier shall make separate deposits for
               field survey Make Ready Work to determine the actual availability
               of space based on Ameritech's records and for the Make Ready Work
               to prepare the Rights-of-way or conduit for the Requesting
               Carrier's Attachment.

          d.   In the event that other Requesting Carriers, including Ameritech,
               share in the responsibility for the modification to Ameritech's
               Structure, the deposits required by this section shall be the
               Requesting Carrier's proportionate share of the Make Ready Work
               Charges.

     4.   Attachment Fees. Attachment Fees are the recurring charges to the 
Requesting Carrier to place and maintain its Attachments in or on Ameritech's 
Structure.

          a.   Attachment Fees are due and payable twice each Contract Year in
               advance. On January 1 of each year, the Requesting Carrier will
               be billed for its Attachments to Ameritech's Structure in place
               and for which Make Ready Work has been completed as of December 1
               of the previous year. On July 1 of each Contract Year, the
               Requesting Carrier will be billed for its Attachments to
               Ameritech's Structure in place and for which Make Ready Work has
               been completed as of June. Any Attachments made within each
               billing period will be billed at the time of the Attachment for
               the entire billing period.

          b.   Pole Attachment Fees

               i)   The Attachment Fee for poles applies to each pole on which
                    the Requesting Carrier has placed it Attachment or for which
                    Make Ready Work pursuant to a request for access has been
                    completed.

               ii)  Pole Attachment Fee: $1.97 per pole, per year for each one
                    foot of space occupied by the Requesting Carrier's
                    Attachments.

                               Exhibit PS-VIII-3
<PAGE>
 
          c.   Duct or Conduit Attachment Fees

               i)   The Attachment Fee for duct or conduit applies to the total
                    number of feet of Ameritech's conduit system or ducts in
                    which the Requesting Carrier placed Attachments or for which
                    Make Ready Work pursuant to a request for access has been
                    completed.

               ii)  The length of the duct or conduit occupied is measured from
                    wall to wall of the manholes, or from the wall of the
                    manhole to the end of the Ameritech's conduit system or duct
                    occupied by the Requesting Carrier's Attachment, plus the
                    cable racking and maintenance loop space measured by the
                    length of the Requesting Carrier's cable within each
                    manhole.

               iii) If Requesting Carrier's partial occupancy of a continuous
                    conduit system or duct renders the remainder of any portion
                    thereof unusable, the Attachment Fee applies to both the
                    portion occupied and the portion unusable.

               iv)  If Requesting Carrier occupies an entire duct, the
                    Attachment Fee shall be twice (2) times the rate per Inner-
                    duct foot for the Attachment.

               v)   Conduit Attachment Fee:

                    $.33 per foot of Inner-duct or cable racking an maintenance 
                    loop space occupied per year.
   
          d.   Rights-of-Way Attachment Fees:

               i)   The Attachment Fee for use of linear rights-of-way applies
                    to the total linear footage of strips of land three feet
                    (3') wide suitable for direct buried or trench placement of
                    cable facilities of Ameritech's right-of-way in which the
                    Requesting Carrier has placed Attachments or for which Make
                    Ready Work pursuant to a request for access has been
                    completed and is priced on a case-by-case basis.

               ii)  If Requesting Carrier's partial occupancy of a continuous
                    linear right-of-way renders the remainder or any portion
                    thereof unusable, the Attachment Fee applies to both the
                    portion occupied and the portion rendered unusable.

               iii) The Attachment Fees for the Requesting Carrier's equipment
                    cabinets or enclosures placed on Ameritech's rights-of-way
                    will be priced on a case-by-case basis, depending upon the
                    proposed Attachment and the characteristics of the right-of-
                    way in question including the consumption of useable space
                    of the right-of-way by the Attachment and its useability for
                    the Attachments of others, including Ameritech's, after the
                    Attachment.

                               Exhibit PS-VIII-4
<PAGE>
 
               iv)  The Attachment Fees for the Requesting Carrier's Attachments
                    to Ameritech's rights-of-way within buildings or on campuses
                    owned by third parties will be priced on a case-by-case
                    basis, depending upon the proposed Attachment and the
                    characteristics of the right-of-way the Attachment and its
                    useability for the Attachments of others, including
                    Ameritech's after the Attachment, and the cost of Ameritech
                    of the right-of-way in question.

          e.   Period Inspection Fees

               Periodic inspection fees will be assessed to cover the Requesting
               Carrier's portion of the costs to Ameritech to make periodic
               inspections of its Structure with respect to the Attachments of
               the Attaching Party and other attaching parties.

                               Exhibit PS-VIII-5
<PAGE>
 
RATE ELEMENT                  MONTHLY CHARGE          NON-RECURRING CHARGE/2/
                                                                           -

 ADMINISTRATIVE CHANGE CHARGE                           $50.00
INITIAL ADDRESS MESSAGE (IAM)- $0.0011500 PER MESSAGE

RECIPROCAL COMPENSATION = $XXXX PER MINUTE FOR LOCAL CALLS /4/
                                                            -


/4/  Ameritech and Focal do not agree on the Reciprocal Compensation rate to be
 -   paid by Ameritech for Local Traffic terminating on Focal's network. Focal
     will bill Ameritech at $0.005956 per minute for Local Traffic. Ameritech
     disagrees and believes the rate is $0.0050000 and will dispute Focal's
     billing in accordance with its rights under Section 28.2 of the Agreement.
     Either Party may reslove the dispute consistent with Section 28.3 of the
     Agreement. The Parties will true-up the difference, if any, after the
     correct rate is determined pursuant to Section 28.3.

                              Exhibit PS-VIII-A-2

<PAGE>
 
                                   Exhibit A
                                   ---------

                          FOCAL/AMERITECH FIBER MEET


                            [DIAGRAM APPEARS HERE]


                               EXHIBIT PS-VIII-A
                    Focal Network Interconnection Services/1/
                                    Michigan
<TABLE>
<CAPTION>
Rate Element                                       Monthly Charge                  Non-recurring Charge/2/
<S>                                                <C>                             <C>
DS1 Collocation Termination Charge per DS1/3/
   1 -   28 DS1s                                      $ 36.00                            $267.00
  29 -   56 DS1s                                      $ 33.00                            $267.00
  57 -   84 DS1s                                      $ 26.00                            $267.00
  85 -  112 DS1s                                      $ 21.00                            $267.00
 113 -  140 DS1s                                      $ 17.00                            $267.00
 141 -  168 DS1s                                      $ 13.00                            $267.00
 169 -  300 DS1s                                      $ 12.00                            $175.00
 301 -  500 DS1s                                      $ 12.00                            $125.00
 501 -  750 DS1s                                      $ 12.00                            $ 75.00
 751 - 1000 DS1s                                      $ 12.00                            $ 50.00
1001+                                                 $ 12.00                            $ 25.00

DS3 to DS1 Multiplexing                               $620.00
 per DS3
Leased DS1 Facility
      w/o mileage                                     $186.00
      w/ mileage                                      $334.00 + $25.00 per mile
Signaling Link Port                                   $450.00                            $475.00
Termination
Installation per DS1 Trunk                                                               $177.50
Group
Service Order Charge Per                                                                 $ 50.00
Order
Engineering Charge per                                                                   $120.00
DS1 Trunk Group
Service Order Change Charge                                                              $ 50.00
</TABLE>

/1/  The rates in this Exhibit are subject to change if the rates Ameritech
     charges Focal for comparable services provided under the Agreement change.

/2/  For moves within the same Focal Wire Center, which are not initiated by
     Focal, the Service Order Charge and one-half of the non-recurring charges
     will apply.

/3/  The DS1 Collocation Termination charge permits the Co-Carrier to
     terminate Co-Carrier provided facilities in the Co-Carrier equipment
     residing within Focal furnished, engineered and installed space and
     includes cross-connect to Focal equipment. It applies per terminated DS1
     and not to spare DS1 capacity or access services Focal purchases from
     Ameritech. However, if a DS3 is terminated and Focal provides multiplexing,
     Ameritech must pay 28 DS1 Collocation Termination charges even if all
     trunks are not used. Ameritech acknowledges that the DS1 Collocation
     Termination charge will be identified on invoices as a "DS1 Port
     Termination Charge."

                              Exhibit PS-VIII-A-1
<PAGE>
 
                        REPRESENTATION OF AUTHORIZATION

     Ameritech hereby represents to Focal, for purposes of obtaining a
Customer's Customer Proprietary Network Information ("CPNI") or for placing an
order to change or establish a Customer's service, that it is a duly
certificated LEC and that it is authorized to obtain CPNI and to place orders
for Telephone Exchange Service (including Resale Service) upon the terms and
conditions contained herein.

1.   With respect to requests for CPNI regarding prospective Customers of
     Ameritech, Ameritech acknowledges that it must obtain written or
     electronic authorization in the form of a signed letter, tape-recorded
     conversation, password verification, or other means ("Documentation of
     Authorization") which explicitly authorizes Ameritech to have access to the
     prospective Customer's CPNI. The Documentation of Authorization must be
     made by the prospective Customer or the prospective Customer's authorized
     representative. In order to obtain the CPNI of the prospective Customer,
     Ameritech must submit to Focal the Documentation of Authorization. If
     Ameritech cannot provide applicable Documentation of Authorization, then
     Focal shall not provide CPNI to Ameritech.

2.   If Ameritech has already obtained Documentation of Authorization for the
     Customer to place an order for Telephone Exchange Service for the Customer,
     Ameritech need not submit Documentation of Authorization to obtain the
     Customer's CPNI.

3.   With respect to placing a service order for Telephone Exchange Service
     (including Resale Services) for a Customer, Ameritech acknowledges that it
     must obtain Documentation of Authorization which explicitly authorizes
     Ameritech to provide Telephone Exchange Service to such Customer. The
     Documentation of Authorization must be made by the prospective Customer or
     Customer's authorized representative. Ameritech need not submit the
     Documentation of Authorization to process a service order. However,
     Ameritech hereby represents that it will not submit a service order to
     Focal unless it has obtained appropriate Documentation of Authorizaton from
     the prospective Customer and has such Documentation of Authorization in its
     possession.

4.   The Documentation of Authorization must clearly and accurately identify 
     Ameritech and the prospective Customer.
 
5.   Ameritech shall retain all Documentation of Authorization in its files for
     as long as Ameritech provides Telephone Exchange Service to the Customer,
     or for as long as Ameritech makes requests for information on behalf of the
     Customer.

6.   Ameritech shall make Documentation of Authorization available for
     inspection by Focal during normal business hours. In addition, Ameritech
     shall provide Documentation of Authorization for Customers or prospective
     Customers to Focal upon request.
 

<PAGE>

7.   Ameritech is responsible for, and shall hold Focal harmless from, any and
     all Losses (as defined in that certain Interconnection Agreement under
     Sections 251 and 252 of the Telecommunications Act of 1996 dated as of
     January 29, 1997 by and between Ameritech Information Industry Services, a
     division of Ameritech Services, Inc. on behalf of and as agent for
     Ameritech Michigan and Focal Communications Corporation of Michigan, (the
     "Interconnection Agreement") resulting from Focal's reliance upon
     Ameritech's representations as to its authority to act on behalf of a
     Customer or prospective Customer in obtaining CPNI or placing a service
     order for Telephone Exchange Service.


8.   If Ameritech fails to repeatedly and materially abide by the procedures set
     forth herein, Focal reserves the right to insist upon the submission of
     Documentation of Authorization for each Customer in connection with a
     request for a service order.

9.   This Representation of Authorization shall commence on the date noted below
     and shall continue in effect until the termination or expiration of the
     Interconnection Agreement.

     Dated this 10th day of February 1999.

AMERITECH INFORMATION INDUSTRY
SERVICES, A DIVISION OF AMERITECH
SERVICES, INC., ON BEHALF OF AND
AS AGENT FOR AMERITECH MICHIGAN

By: /s/ Theodore Edwards
   --------------------------------    
Title: Vice President
      -----------------------------
Printed Name: Theodore A. Edwards
             ----------------------

                                       2

<PAGE>

                                                                         EX 10.6
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                         DATED AS OF FEBRUARY 15, 1999

                                BY AND BETWEEN

              NEW ENGLAND TELEPHONE AND TELEGRAPH COMPANY,
                                     D/B/A
                         BELL ATLANTIC - MASSACHUSETTS

                                      AND

               FOCAL COMMUNICATIONS CORPORATION OF MASSACHUSETTS
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement (this "Agreement"), under Sections 251 and
252 of the Telecommunications Act of 1996 (the "Act"), is effective as of the
15th day of February, 1999 (the "Effective Date"), by and between New England
Telephone and Telegraph Company, d/b/a Bell Atlantic - Massachusetts ("BA"), a
Massachusetts corporation with offices at 185 Franklin Street, Boston,
Massachusetts, 02110, and Focal Communications Corporation of Massachusetts,
("Focal") a Delaware corporation with offices at 200 N. LaSalle Street, Suite
800, Chicago, Illinois 60601 (each a 'Party" and, collectively, the "Parties").

     WHEREAS, Focal has requested that BA make available to Focal
Interconnection service and unbundled Network Elements upon the same terms and
conditions as provided in the Interconnection Agreement (and amendments thereto)
between Norfolk County Internet, Inc. and BA, dated as of October 2, 1998, for
Massachusetts, approved by the Department under Section 252 of the Act the
(together with all appendices thereto,"Separate Agreement") and attached as
Appendix 1 hereto; and

     WHEREAS, BA has undertaken to make such terms and conditions available to
Focal hereby only because of and, to the extent required by, Section 252(i) of
the Act.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Focal and BA hereby agree as follows:

     1.0  INCORPORATION OF APPENDICES BY REFERENCE

     1.1  Except as expressly stated herein, the terms and conditions of the
Separate Agreement (as set forth in Appendix 1 hereto), as it is in effect on
the date hereof after giving effect to operation of law, and of the other
Appendices hereto, are incorporated by reference in their entirety herein and
form an integral part of this Agreement.

     1.2  References in Appendix 1 hereto to Norfolk County Internet, Inc. or to
NCI shall for purposes of this Agreement be deemed to refer to Focal.

     1.3  References in Appendix 1 hereto to the "Effective Date", the date of
effectiveness thereof and like provisions shall for purposes of this Agreement
be deemed to refer to the date first written above. Unless terminated earlier in
accordance with the terms of Appendix 1 hereto, this Agreement shall continue in
effect until the Separate Agreement expires or is otherwise terminated.

     1.4  All references in Appendix 1 hereto to "800/888" shall be deleted in
their entirety and replaced with the following: "800/888/877".
<PAGE>
 
     1.5  All usage data to be provided pursuant to Sections 6.3.8 and 6.3.9 of
Appendix 1 to Appendix 1 hereto shall be sent to the following address on behalf
of Focal:

          Focal Communications Corporation of Massachusetts
          Attn: Director Regulatory Affairs
          200 N. LaSalle Street/Suite 800 Chicago, Illinois 60601

     1.6  All notices, affidavits, exemption-certificates or other
communications to Focal related to tax matters shall be sent to the following
address:

          Focal Communications Corporation of Massachusetts
          Attn: Director Regulatory Affairs
          200 N. LaSalle Street
          Suite 800
          Chicago, Illinois 60601

     1.7  All notices, affidavits, exemption-certificates or other
communications to BA related to tax matters shall be sent to the following
address:

          Tax Administration
          Bell Atlantic Corporation
          1095 Avenue of the Americas
          Room 3109
          New York, New York 10036
          Telephone: (212) 395-1280
          Facsimile: (212) 597-2915

     1.8  Notices to Focal under Section 29. 10 of Appendix I to Appendix I
hereto shall be sent to the following address:

          Focal Communications Corporation of Massachusetts
          Attn: Director Regulatory Affairs
          200 N. LaSalle Street
          Suite 800
          Chicago, Illinois 60601

     1.9  Notices to BA under Section 29.10 of Appendix I to Appendix I hereto
shall be sent to the following address:

          President - Telecom Industry Services
          Bell Atlantic Corporation
          1095 Avenue of the Americas
                                       2
<PAGE>
 
          40th Floor
          New York, New York 10036
          Facsimile: (212) 597-2585

          with a copy to:

          Bell Atlantic Network Services, Inc.
          Attn: Jack H. White
                Associate General Counsel
          1320 N. Court House Road,8th Floor
          Arlington, Virginia 22201
          Telephone: (703) 974-1368
          Facsimile: (703) 974-0744

          with a copy to:

          Bell Atlantic Massachusetts
          Attn: Bruce P. Beausejour
                General Counsel
          185 Franklin Street
          Room 1403
          Boston, MA 02110
          Telephone: (617) 743-2445
          Facsimile: (617) 737-0648

     1.10 Schedule 4.0 set forth at Appendix 2 hereto shall replace and
supersede in its entirety Schedule 4.0 of Appendix 1 hereto.

     2.0  CLARIFICATIONS

     2.1  The entry into, filing and performance by BA of this Agreement does
not in any way constitute a waiver by BA of any of the rights and remedies it
may have to seek review of any of the provisions of the Separate Agreement, or
to petition the Department, other administrative body or court for
reconsideration or reversal of any determination made by any of them, or to seek
review in any way of any portion of this Agreement in connection with Focal's
election under Section 252(i) of the Act. Similarly, the entry into, filing and
performance by Focal of this Agreement does not in any way constitute a waiver
by Focal of its right to seek review by the Department or any other regulatory
or administrative body or court of BA's rejection of Focal's 12/29/98 request
pursuant to 252(i) to opt in to the agreement between BA and XCOM

     2.2  The Parties acknowledge that Focal's election to opt in to the NCI
agreement occurred subsequent to the DTE's 10\26\98 Order in Docket No. 97-116,
which determined that Internet traffic is Local Traffic for purposes of
Reciprocal Compensation and therefore required
                                       3
<PAGE>
 
BA to pay Massachusetts CLECs reciprocal compensation for termination of local
traffic to ISPs. BA shall comply with that order with respect to Focal until the
FCC, the DTE, or a court of competent jurisdiction with respect to this
agreement determines otherwise.

     IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be
executed as of this 15th day of February, 1999.


FOCAL COMMUNICATIONS               BELL ATLANTIC-MASSACHUSETTS, INC.
CORPORATION OF MASSACHUSETTS


By:/s/ John R. Barnicle            By:/s/ Jeffrey A. Masoner
   --------------------               -----------------------
Printed: JOHN R BARNICLE           Printed: Jeffrey A. Masoner
        ----------------                   -------------------
Title:   C.O.O.                    Title: Vice-President- Interconnection
      ------------------                 --------------------------------   
                                          Services Policy & Planning
                                         --------------------------------

                                       4

<PAGE>
 
                                  APPENDIX 1
<PAGE>
 
          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

                          DATED AS OF OCTOBER 2, 1998

                                BY AND BETWEEN

                         BELL ATLANTIC - MASSACHUSETTS

                                      AND

                         NORFOLK COUNTY INTERNET, INC.
<PAGE>
 

                               TABLE OF CONTENTS

<TABLE> 
<CAPTION> 
Section                                                                     Page
<S>                                                                         <C> 
1.0  DEFINITIONS                                                               2

2.0  INTERPRETATION AND CONSTRUCTION                                          12

3.0  SCOPE                                                                    12
     
4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)                            13
     4.1  Scope                                                               13
     4.2  Physical Architecture                                               14
     4.3  Technical Specifications                                            15
     4.4  Interconnection in Additional LATAs                                 15

5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE
     TRAFFIC PURSUANT TO SECTION 251(c)(2)                                    16
     5.1  Scope of Traffic                                                    16
     5.2  Switching System Hierarchy                                          16
     5.3  Trunk Group Architecture and Traffic Routing                        17
     5.4  Signaling                                                           18
     5.5  Grades of Service                                                   18
     5.6  Measurement and Billing                                             18
     5.7  Reciprocal Compensation Arrangements -- Section 251(b)(5)           19
     
6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC
     PURSUANT TO 251(c)(2)                                                    21
     6.1  Scope of Traffic                                                    21
     6.2  Trunk Group Architecture and Traffic Routing                        21
     6.3  Meet-Point Billing Arrangements                                     21

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC
     7.1  Information Services Traffic
     7.2  Tandem Transit Service
     7.3  911/E911 Arrangements

8.0  NUMBER RESOURCES, RATE CENTERS,AND RATING POINTS                         26
  
9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES                              27
     9.1  Cooperation                                                         27
     9.2  Responsibility for Following Standards                              27
     9.3  Interference or Impairment                                          27
</TABLE> 


                                                                           i 
<PAGE>
 

     9.4  Repeated or Willful Noncompliance                                   27
     9.5  Outage Repair Standard                                              28
     9.6  Notice of Changes - Section 251(c)(5)                               28
     9.7  Fraud                                                               28

10.0 JOINT NETWORK IMPLEMENTATION AND GROOMING PROCESS,
     INSTALLATION, MAINTENANCE, TESTING & REPAIR                              29
     10.1 Joint Network Configuration and Grooming Process                    29
     10.2 Installation, Maintenance, Testing and Repair                       29
     10.3 Network Reliability Council                                         29
     10.4 Forecasting Requirements for Trunk Provisioning                     30
     10.5 Demand Management Forecasts                                         31

11.0 UNBUNDLED ACCESS -- SECTION 251(c)(3)                                    32
     11.1  Available Network Elements                                         32
     11.2  Unbundled Local Loop ("LJLL") Types                                32
     11.3  Unbundled Switching Elements                                       34
     11.4  Unbundled Inter Office Facilities                                  34
     11.5  Operations Support Systems                                         34
     11.6  Limitations on Unbundled Access                                    34
     11.7  Availability of Other Network Elements on an Unbundled Basis       35
     11.8  Provisioning of Unbundled Local Loops                              35
     11.9  Maintenance of Unbundled Network Elements                          37
     11.10 Other Terms and Conditions Including Rates and Charges             37

12.0 RESALE -- SECTION 251(c)(4) and 251(b)(2)                                38
     12.1 Availability of Wholesale Rates for Resale                          38
     12.2 Availability of Retail Rates for Resale                             38
     12.3 Additional Terms Governing Resale and Use of BA Services            38

13.0 COLLOCATION -- SECTION 251(c)(6)                                         40
     13.6  Dedicated Transit Service                                          40

14.0 NUMBER PORTABILITY -- SECTION 251(b)(2)                                  42
     14.1  Scope                                                              42
     14.2  Procedures for Providing INP Through Remote Call Forwarding        42
     14.3  Procedures for Providing INP Through Route Indexing                44
     14.4  Procedures for Providing INP Through Full NXX Code Migration       44
     14.5  Other Interim Number Portability Options                           44
     14.6  Receipt of Terminating Compensation on Traffic to INP'ed Numbers   44
     14.7  Recovery of 1NP Costs Pursuant to FCC Order and Rulemaking         45

15.0 DIALING PARITY -- SECTION 251(b)(3)                                      46

                                                                          ii
<PAGE>
 

16.0 ACCESS TO RIGHTS-OF-WAY -- SECTION 251(b)(4)                             46

17.0 DATABASES AND SIGNALING                                                  46

18.0 COORDINATED SERVICES ARRANGEMENTS                                        47
     18.1 Intercept and Referral Announcements                                47
     18.2 Coordinated Repair Calls                                            47
     18.3 Customer Authorization                                              47

19.0 DIRECTORY SERVICES ARRANGEMENTS                                          49
     19.1  Directory Listings and Directory Distributions                     49
     19.2  Directory Assistance and Operator Services                         50
     19.3  Directory Assistance Call Completion                               51
     19.4  Directory Assistance Credits                                       52
     19.5  Direct Access to Directory Assistance                              52
     19.6  Inward Operator Services                                           52
     19.7  Operator Services                                                  53
     19.8  0+ Mechanized Operator Calls (Calling Card, Collect,
            Bill to Third Number)                                             54
     19.9  0- Operator Handled Calls (Calling Card, Collect,
           Bill to Third Number)                                              54
     19.10 Operator Emergency Bulletin Service                                55
     19.11 Operator Passthrough Service                                       55

20.0 COORDINATION WITH TARIFF TERMS                                           56

21.0 INSURANCE                                                                57

22.0 TERM AND TERMINATION                                                     58

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES                             58

24.0 CANCELLATION CHARGES                                                     59

25.0 INDEMNIFICATION                                                          59

26.0 LIMITATION OF LIABILITY.                                                 60

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES                           61
     27.1 Performance Standards                                               61
     27.2 Performance Reporting                                               61

28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL                                62

                                                                         iii
<PAGE>
 

29.0 MISCELLANEOUS                                                            63
     29.1  Authorization                                                      63
     29.2  Independent Contractor                                             63
     29.3  Force Majeure                                                      63
     29.4  Confidentiality                                                    64
     29.5  Choice of Law                                                      65
     29.6  Taxes                                                              65
     29.7  Assignment                                                         65
     29.8  Billing and Payment; Disputed Amounts                              65
     29.9  Dispute Resolution                                                 67
     29.10 Notices                                                            67
     29.11 Section 252(i) Obligations                                         68
     29.12 Joint Work Product                                                 68
     29.13 No Third Party Beneficiaries; Disclaimer of Agency                 68
     29.14 No License                                                         69
     29.15 Technology Upgrades                                                70
     29.16 Survival                                                           70
     29.17 Entire Agreement                                                   70
     29.18 Counterparts                                                       70
     29.19 Modification, Amendment, Supplement, or Waiver                     70
     29.20 Successors and Assigns                                             70
     29.21 Publicity and Use of Trademarks or Service Marks                   70
     29.22 Restructured/New Rates                                             70
     29.23 Integrity of BELL ATLANTIC Network                                 71

                                                                           iv
<PAGE>

LIST OF SCHEDULES AND EXHIBITS

                                   Schedules

Schedule 1.0      Certain Terms As Defined in the Act, As of the Effective Date

Schedule 4.0      Network Interconnection Schedule

Schedule 7.1.4    Billing Arrangements for Variable-Rated Information Services
                  Calls

Exhibits

Exhibit A         Bell Atlantic - Massachusetts and NCI Pricing Schedule

Exhibit B         Network Element Bona Fide Request

Exhibit C         Directory Assistance and IntraLATA Operator Services
                  Agreement for Competitive Local Exchange Carriers

                                                                             v
<PAGE>
 

          INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                        TELECOMMUNICATIONS ACT OF 1996

     This Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996 ("Agreement"), is effective as of the 2nd day of
October, 1998 (the "Effective Date"), by and between New England Telephone and
Telegraph Company d/b/a Bell AtlanticMassachusetts ("BA" or "Bell Atlantic'), a
New York corporation with offices at 185 Franklin Street, Boston, MA, 02110, and
Norfolk County Internet, Inc. ("NCI"), a Massachusetts corporation, with offices
at Unit 12A, Depot Plaza, 13-25 Main Street, Franklin, Massachusetts, 02038.

     WHEREAS, the Parties want to interconnect their networks at mutually agreed
upon points of interconnection to provide Telephone Exchange Services, Switched
Exchange Access Services, and other Telecommunications Services (all as defined
below) to their respective customers;

     WHEREAS, the Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will interconnect their networks and provide other services as
required by the Act (as defined below) and additional services as set forth
herein; and

     WHEREAS, Sections 251, 252, and 271 of the Telecommunications Act of 1996
have specific requirements for interconnection, unbundling, and service resale,
commonly referred to as the "Checklist", and the Parties intend that this
Agreement meet those Checklist requirements.

     NOW, THEREFORE, in consideration of the mutual provisions contained herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, NCI and BA hereby agree as follows:

     This Agreement sets forth the terms, conditions and pricing under which BA
and NCI (individually, a "Party" and collectively, the "Parties") will offer and
provide to each other network Interconnection, access to Network Elements,
ancillary services, and wholesale Telecommunications Services available for
resale within each LATA in which they both operate within the Commonwealth of
Massachusetts. As such, this Agreement is an integrated package that reflects a
balancing of interests critical to the Parties. It will be submitted to the
Massachusetts Department of Telecommunications and Energy, and the Parties will
specifically request that the DTE refrain from taking any action to change,
suspend or otherwise delay implementation of the Agreement.

1.0  DEFINITIONS

     As used in this Agreement, the following terms shall have the meanings
specified below in this Section 1.0. For convenience of reference only, the
definitions of certain terms that are As
                                                                               1
<PAGE>
 

Defined in the Act (as defined below) are set forth on Schedule 1.0. Schedule
1.0 sets forth the definitions of such terms as of the date specified on such
Schedule and neither Schedule 1.0 nor any revision, amendment or supplement
thereof intended to reflect any revised or subsequent interpretation of any term
that is set forth in the Act is intended to be a part of or to affect the
meaning or interpretation of this Agreement.

     1.1 "Act" means the Communications Act of 1934 (47 U.S.C.(S)151 et seq.) as
                                                                     ------ 
amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or a
Commission within its state of jurisdiction.

     1.2 "ADSU or "Asymmetrical Digital Subscriber Line" is a digital loop
transmission technology which permits the transmission of up to 6 Mbps
downstream (from the CO to the end-user customer) and up to 640 kbps digital
signal upstream (from the end-user customer to the CO).

     1.3 "Affiliate" is As Defined in the Act.

     1.4 "Agreement" means this Interconnection Agreement under Sections 251 and
252 of the Act and all the Exhibits, Schedules, addenda, and attachments
referenced herein and/or appended hereto

     1.5 "Agreement for Switched Access Meet Point Billing" means the Agreement
for Switched Access Meet Point Billing between the Parties.

     1.6 "Ancillary Traffic" means all traffic that is destined for ancillary
services, or that may have special billing requirements, including but not
limited to the following: BLV/BLVI, Directory Assistance, 911/E911, Operator
Services (IntraLATA call completion), IntraLATA third party, collect and calling
card, 800/888 database query, LIDB, and information services requiring special
billing arrangements between the Parties.

     1.7 "Applicable Laws" or "Applicable Law" means all laws, regulations, and
orders applicable to each Party's performance of its obligations hereunder.

     1.8 "As Defined in the Act" means as specifically defined by the Act and
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     1.9 "As Described in the Act" means as described in or required by the Act
and as from time to time interpreted in the duly authorized rules and
regulations of the FCC or the Commission.

     1.10"Automatic Number Identification" or "ANI" means a Feature Group D
signaling parameter which refers to the number transmitted through a network
identifying the billing number of the calling party.

                                                                               2
<PAGE>
 

     1.11 "Bona Fide Request" or "BFR" means the process described on Exhibit B
that prescribes the terms and conditions relating to a Party's request that the
other Party provide a BFR Item (as defined in Exhibit B) not otherwise provided
by the terms of this Agreement.

     1.12 "Busy Line Verification" or "BLV" means an operator request for a
status check on the line of a called party. The request is made by one Party's
operator to an operator of the other Party. The verification of the status check
is provided to the requesting operator.

     1.13 "Busy Line Verification Interrupt" or "BLVI" means a service that may
be requested and provided when Busy Line Verification has determined that a line
is busy due to an ongoing call. BLVI is an operator interruption of that ongoing
call to inform the called party that a calling party is seeking to complete his
or her call to the called party.

     1.14 "Calling Party Number" or "CPN" is a Common Channel Signaling ("CCS")
parameter which refers to the number transmitted through a network identifying
the calling Party.

     1.15 "Central Office Switch" means a switch used to provide
Telecommunications Services, including, but not limited to:

          (a) "End Office Switch" or "End Office" is a switching entity that is
     used to terminate Customer station Loops for the purpose of Interconnection
     to each other and to trunks;and

          (b) "Tandem Office Switch" or "Tandem Office" or "Tandem" is a
     switching entity that has billing and recording capabilities and is used to
     connect and switch trunk circuits between and among End Office Switches and
     between and among End Office Switches and carriers' aggregation points,
     points of termination, or points of presence, and to provide Switched
     Exchange Access Services.

     A Central Office Switch may also be employed as a combination End
Office/Tandem Office Switch.

     1.16 "CLASS Features" means certain CCS-based features available to
Customers including, but not limited to: Automatic Call Back; Call Trace; Caller
Identification; Call Return and future CCS-based offerings.

     1.17 "Collocation" means an arrangement whereby one Party's (the
"Collocating Party") facilities are terminated in its equipment necessary for
Interconnection or for access to Network Elements offered by the second Party on
an unbundled basis that has been installed and maintained at the premises of a
second Party (the "Housing Party"). For purposes of Collocation, the "premises"
of a Housing Party is limited to a Housing Party Wire Center, other mutually
agreedupon locations of the Housing Party, or any location for which Collocation
has been
                                                                               3
<PAGE>

ordered by the FCC or Commission. Collocation may be "physical" or "virtual". In
"Physical Collocation", the Collocating Party installs and maintains its own
equipment in the Housing Party's premises. In "Virtual Collocation", the Housing
Party owns, installs, and maintains equipment dedicated to use by the
Collocating Party in the Housing Party's premises. BA currently provides
Collocation under terms, rates, and conditions as described in tariffs on file
or soon to be filed with the FCC or the Commission.

     1.18 "Commission" or "DTE" means the Massachusetts Department of
Telecommunications and Energy.

     1.19 "Common Channel Signaling" or "CCS" means the signaling system,
developed for use between switching systems with stored-program control, in
which all of the signaling information for one or more groups of trunks is
transmitted over a dedicated high-speed data link rather than on a per-trunk
basis and, unless otherwise agreed by the Parties, the CCS used by the Parties
shall be SS7.

     1.20 "Competitive Local Exchange Carrier" or "CLEC" means any Local
Exchange Carrier other than BA, operating as such in BA's service territory in
Massachusetts. NCI is or will shortly become a CLEC.

     1.21 "Cross Connection" means a jumper cable or similar connection provided
pursuant to Collocation at the Digital Signal Cross Connect, Main Distribution
Frame or other suitable frame or panel between (i) the Collocating Party's
equipment and (ii) the equipment or facilities of the Housing Party.

     1.22 "Customer" means a third-Party residence or business that subscribes
to Telecommunications Services provided by either of the Parties.

     1.23 "Customer Proprietary Network Information" or "CPNI" is As Defined in
           the Act.

     1.24 "Dialing Parity" is As Defined in the Act. As used in this Agreement,
Dialing Parity refers to both Local Dialing Parity and Toll Dialing Parity.
"Local Dialing Parity" means the ability of Telephone Exchange Service Customers
of one LEC to select a provider and make local calls without dialing extra
digits. "Toll Dialing Parity" means the ability of Telephone Exchange Service
Customers of a LEC to place toll calls (inter or IntraLATA) which are routed to
a toll carrier (IntraLATA or InterLATA) of their selection without dialing
access codes or additional digits and with no unreasonable dialing delay.

     1.25 "Digital Signal Level" means one of several transmission rates in the
time-division multiplex hierarchy.

     1.26 "Digital Signal Level 0" or "DSO" means the 64 Kbps zero-level signal
in the time-division multiplex hierarchy.
                                                                               4
<PAGE>
 

     1.27 "Digital Signal Level 1" or "DS1" means the 1.544 Mbps first-level
signal in the timedivision multiplex hierarchy. In the time-division
multiplexing hierarchy of the telephone network, DS1 is the initial level of
multiplexing.

     1.28 "Digital Signal Level 3" or "DS3" means the 44.736 Mbps third-level in
the timedivision multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS3 is defined as the third level of
multiplexing.

     1.29 "Exchange Access" is As Defined in the Act.

     1.30 "Exchange Message Interface" or "EMI" means the standard used for
exchange of telecommunications message information among Telecommunications
Carriers for billable, nonbillable, sample, settlement and study data. EMI
format is contained in document SR-320 published by Alliance for
Telecommunications Industry Solutions ("ATIS"), which defines industry standards
for Exchange Message Interface.

     1.31 "FCC" means the Federal Communications Commission.

     1.32 "FCC Regulations" means Title 47 of the Code of Federal Regulations.

     1.33 "Fiber Meet" means an Interconnection architecture method whereby the
Parties physically Interconnect their networks via an optical fiber interface
(as opposed to an electrical interface) at a mutually agreed upon location.

     1.34 HDSL is a digital loop transmission technology which permits the
transmission of up to 768 kbps simultaneously in both directions on a single 
non-loaded, twisted copper pair or up to 1544 kbps simultaneously in both
directions on two non-loaded, twisted copper pairs.

     1.35 "Incumbent Local Exchange Carrier" or "ILEC" is As Defined in the Act.
For purposes of this Agreement, BA is an Incumbent Local Exchange Carrier.

     1.36 "Independent Telephone Company" or "ITC" means any entity other than
BA which, with respect to its operations within Massachusetts, is an Incumbent
Local Exchange Carrier.

     1.37 "Information Services" is As Defined in the Act.

     1.38 "Information Service Traffic" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which is
addressed to an information service provided over a Party's switched voice
information services platform (i.e., 976, 550, 540, 970,940).
                               ----                                         5
<PAGE>

     1.39 "Inside Wire" or "Inside Wiring" means all wire, cable, terminals,
hardware, and other equipment or materials on the Customer's side of the Rate
Demarcation Point.

     1.40 "Integrated Digital Loop Carrier" or "IDLC" means a subscriber loop
carrier system which integrates within the switch at a DS I level that is
twenty-four (24) loop transmission paths combined into a 1.544 Mbps digital
signal.

     1.41 "Integrated Services Digital Network" or "ISDN" means a switched
network service that provides end-to-end digital connectivity for the
simultaneous transmission of voice and data. Basic Rate Interface-ISDN (BRI-
ISDN) provides for a digital transmission of two 64 Kbps bearer channels and one
16 Kbps data and signaling channel (2B+D). Primary Rate Interface-ISDN ("PRI-
ISDN") provides for digital transmission of twenty three (23) 64 kbps bearer
channels and one (1) 64 kpbs data and signaling channel (23 B+D).

     1.42 "Interconnection" is As Described in the Act and refers to the
connection of separate pieces of equipment or transmission facilities within,
between, or among networks for the purpose of transmission and routing of
Telephone Exchange Service traffic and Exchange Access traffic.

     1.43 "Interexchange Carrier" or "IXC" means a carrier that provides,
directly or indirectly, InterLATA or IntraLATA Telephone Toll Services.

     1.44 "Interim Telecommunications Number Portability" or "INP" is As
          Described in the Act.

     1.45 "InterLATA Service" is As Defined in the Act.

     1.46 "IntraLATA Toll Traffic" means those intraLATA calls that are not
defined as Local Traffic in this Agreement.

     1.47 "Line Side" means an End Office Switch connection that provides
transmission, switching and optional features suitable for Customer connection
to the public switched network, including loop start supervision, ground start
supervision, and signaling for basic rate ISDN service.

     1.48 "Local Access and Transport Area" or "LATA" is As Defined in the Act.

     1.49 "Local Exchange Carrier" or "LEC" is As Defined in the Act. The
Parties to this Agreement are or will shortly become Local Exchange Carriers.

     1.50 "Local Traffic", means traffic that is originated by a Customer of one
Party on that Party's network and terminates to a Customer of the other Party on
that other Party's network, within a given local calling area, or expanded area
service ("EAS") area, as defined in
                                                                               6
<PAGE>
 

BA's effective Customer tariffs, or, if the Commission has defined local calling
areas applicable to all LECs, then as so defined by the Commission.

     1.51 "Main Distribution Frame" or "MDF" means the ultimate point at which
outside plant facilities terminate within a Wire Center, for interconnection to
other telecommunications facilities within the Wire Center.

     1.52 "Meet-Point Billing" or "MPB" means the process whereby each Party
bills the appropriate tariffed rate for its portion of a jointly provided
Switched Exchange Access Service as agreed to in the Agreement for Switched
Access Meet Point Billing.

     1.53 "Network Element" is As Defined in the Act.

     1.54 "Network Interface Device" or "NID" means the BA-provided interface
terminating BA's telecommunications network on the property where the Customer's
service is located at a point determined by BA.

     1.55 "North American Numbering Plan" or "NANP" means the numbering plan
used in the United States, Canada, Bermuda, Puerto Rico and certain Caribbean
Islands. The NANP format is a 10-digit number that consists of a 3-digit NPA
code (commonly referred to as the area code), followed by a 3-digit NXX code and
4-digit line number.

     1.56 "Numbering Plan Area", or "NPA" is also sometimes referred to as an
area code. there are two general categories of NPAs. "Geographic NPAs" and "Non-
Geographic NPAs". A Geographic NPA is associated with a defined geographic area,
and all telephone numbers bearing such NPA are associated with services provided
within that geographic area. A Non-Geographic NPA, also known as a "Service
Access Code" or "SAC Code", is typically associated with a specialized
telecommunications service which may be provided across multiple geographic NPA
areas; 800, 900, 700, 500 and 888 are examples of Non-Geographic NPAs.

     1.57 "Number Portability" or "NP" is As Defined in the Act.

     1.58 "NXV, "NXX Code", or "End Office Code" means the three-digit switch
entity indicator (i.e. the first three digits of a seven digit telephone
number).

     1.59 "Party" means either BA or NCI and "Parties" means BA and NCI.

     1.60 "Permanent Number Portability" or "PNP" means the use of a database or
other technical solution that comports with regulations issued by the FCC to
provide Number Portability for all customers and service providers.

     1.61 "Port Element" or "Port" means a termination on a Central Office
Switch that permits Customers to send or receive Telecommunications over the
public switched network, but
                                                                               7
<PAGE>
 

does not include switch features or switching functionality.

     1.62 "POT Bay" or "Point of Termination Bay" means the intermediate
distributing frame system which serves as the point of demarcation for
collocated Interconnection.

     1.63 "Rate Center" or "Rate Center Area" or "Exchange Area" means the
geographic area that has been identified by a given LEC as being associated with
a particular NPA-NXX code which has been assigned to the LEC for its provision
of Telephone Exchange Services. The Rate Center Area is the exclusive geographic
area which the LEC has identified as the area within which it will provide
Telephone Exchange Services bearing the particular NPA-NXX designation
associated with the specific Rate Center Area. A "Rate Center Point" is the
finite geographic point identified by a specific V&H coordinate (as defined in
Bellcore Special Report SR-TSV-002275), located within the Rate Center Area and
used by that LEC to measure distance for the purpose of billing Customers for
distance sensitive Telephone Exchange Services and Toll Traffic. Rate Centers
will be identical for each Party until such time as NCI is permitted by an
appropriate regulatory body to create its own Rate Centers within an area.

     1.64 "Rate Demarcation Point" means the point where network access
recurring charges and BA responsibility stop and beyond which Customer
responsibility begins, determined in accordance with FCC rules and BA standard
operating practices.

     1.65 "Rating Point" or "Routing Point" means a specific geographic point
identified by a specific V&H coordinate. The Rating Point is used to route
inbound traffic to specified NPANXXs and to calculate mileage measurements for
the distance-sensitive transport charges of switched access services. Pursuant
to Bell Communications Research, Inc. ("Bellcore") Practice BR 795-100-100 (the
"Bellcore Practice"), the Rating Point may be an End Office location. or a "LEC
Consortium Point of Interconnection." Pursuant to that same Bellcore Practice,
each "LEC Consortium Point of Interconnection" shall be designated by a common
language location identifier ("CLLI") code with (x)KD in positions 9, 10, 11,
where (x) may be any alphanumeric A-Z or 0-9. The Rating Point must be located
within the LATA in which the corresponding NPA/NXX is located. However, the
Rating Point associated with each NPA-NXX need not be the same as the
corresponding Rate Center Point, nor must it be located within the corresponding
Rate Center Area, nor must there be a unique and separate Rating Point
corresponding to each unique and separate Rate Center.

     1.66 "Reciprocal Compensation" is As Described in the Act, and refers to
the payment arrangements that recover costs incurred for the transport and
termination of Reciprocal Compensation Traffic originating on one Party's
network and terminating on the other Party's network.

     1.67 "Reciprocal Compensation Call" or "Reciprocal Compensation Traffic"
means a Telephone Exchange Service Call completed between the Parties, which
qualifies for Reciprocal
                                                                               8
<PAGE>
 


Compensation pursuant to the terms of this Agreement and prevailing Commission
or FCC rules that may exist.

     1.68 "Route Indexing" means the provision of Interim Number Portability
through the use of direct trunks provisioned between end offices of BA and NCI
over which inbound traffic to a ported number will be routed.

     1.69 "Service Control Point" or "SCP" means a node in the Common Channel
Signaling network to which informational requests for service handling, such as
routing, are directed and processed. The SCP is a real time database system
that, based on a query from a service switching point and via a Signaling
Transfer Point, performs subscriber or application-specific service logic, and
then sends instructions back to the SSP on how to continue call processing.

     1.70 "Signaling Transfer Point" or "STP" means a specialized switch that
provides SS7 network access and performs SS7 message routing and screening.

     1.71 "Single Bill/Multiple Tariff" shall mean that one bill is rendered to
the IXC from all LECs who are jointly providing access service. A single bill
consists of all rate elements applicable to access services billed on one
statement of charges under one billing account number using each Party's
appropriate access tariffs. The bill could be rendered by or on behalf of,
either of the Parties.

     1.72 "Strapping" means the act of installing a permanent connection between
a point of termination bay and a collocated interconnector's physical
Collocation node.

     1.73 "Switched Access Detail Usage Data" means a category 1101XX record as
defined in the EMI Alliance for Telecommunications Industry Solutions document
SR-320.

     1.74 "Switched Access Summary Usage Data" means a category 1150XX record as
defined in the EMI Alliance for Telecommunications Industry Solutions document
SR-320.

     1.75 "Switched Exchange Access Service" means the offering of transmission
or switching services to Telecommunications Carriers for the purpose of the
origination or termination of Telephone Toll Service. Switched Exchange Access
Services include but may not be limited to: Feature Group A, Feature Group B,
Feature Group D, 700 access, 800 access, 888 access, and 900 access.

     1.76 "Switching Element" is the unbundled Network Element that provides a
CLEC the ability to use switching functionality in a BA End Office switch,
including all vertical services that are available on that switch, to provide
Telephone Exchange Service to its end user customer(s).

                                                                               9
<PAGE>
 


     1.77 "Synchronous Optical Network" or "SONET" means an optical interface
standard that allows inter-networking of transmission products from multiple
vendors. The base transmission rate is 51.84 Mbps (OC-1/STS-1) and higher rates
are direct multiples of the base rate.

     1.78 "Tariff" means any applicable federal or state tariff of a Party, or
standard agreement or other document that sets forth the generally available
terms and conditions, each as may be amended by the Party from time to time,
under which a Party offers a particular service, facility, or arrangement. A
Tariff shall not include BA's "Statement of Generally Available Terms and
Conditions for Interconnection, Unbundled Network Elements, Ancillary Services
and Resale of Telecommunications Services" which has been approved or is pending
approval by the Commission pursuant to Section 252(f) of the Communications Act
of 1934, 47 U.S.C. (S) 252(f).

     1.79 "Technically Feasible Point" is As Described in the Act.

     1.80 "Telecommunications" is As Defined in the Act.

     1.81 "Telecommunications Act" means the Telecommunications Act of 1996 and
any rules and regulations promulgated thereunder.

     1.82 "Telecommunications Carrier" is As Defined in the Act.

     1.83 "Telecommunications Service" is As Defined in the Act.

     1.84 "Telephone Exchange Service" sometimes also referred to as "Exchange
Service," is As Defined in the Act. Telephone Exchange Service generally
provides the Customer with a telephonic connection to, and a unique telephone
number address on, the public switched telecommunications network, and enables
such Customer to place or receive calls to all other stations on the public
switched telecommunications network.

     1.85 "Telephone Exchange Service Call" or "Telephone Exchange Service
Traffic" means a call completed between two Telephone Exchange Service Customers
of the Parties located in the same LATA, originated on one Party's network and
terminated on the other Party's network where such call was not carried by a
third Party as either a presubscribed call (1+) or a casual dialed (10XXX) or
(101XXX) call. Telephone Exchange Service Traffic is transported over Traffic
Exchange Trunks.

     1.86 "Telephone Toll Service" (or "Toll Traffic"), is As Defined in the
Act.

     1.87 "Transit Traffic" means any traffic that originates from or terminates
at NCI's network, "transits" BA's network substantially unchanged, and
terminates to or originates from a

                                                                              10
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement


third carrier's network, as the case may be. "Transit Service" provides NCI with
the ability to use its connection to a BA Tandem for the delivery of calls which
originate or terminate with NCI and terminate or originate from a carrier other
than BA, such as another CLEC, a LEC other than BA, or a wireless carrier. In
these cases, neither the originating nor terminating Customer is a Customer of
BA. This service is provided through BA's Tandems and applies only where the
terminating End Office of the third carrier subtends the BA Tandem. "Transit
Traffic" and "Transit Service" do not include or apply to traffic that is
subject to an effective Meet-Point Billing arrangement.

     1.88 "Trunk Side" means a Central Office Switch connection that is capable
of, and has been programmed to treat the circuit as, connecting to another
switching entity (e.g. another carrier's network). Trunk Side connections offer
                  ---
those transmission and signaling features appropriate for the connection of
switching entities.

     1.89 "Unbundled Local Loop" or "ULL" or "Loop" means a transmission path
that extends from the Main Distribution Frame, DSX panel or functionally
comparable piece of equipment in the Customer's serving End Office to the Rate
Demarcation Point (or network interface device (NID) if installed) in or at a
Customer's premises. The actual loop transmission facilities used to provide an
ULL may utilize any of several technologies.

     1.90 "Undefined Terms" means the Parties acknowledge that terms may appear
in this Agreement which are not defined and agree that any such terms shall be
construed in accordance with their customary usage in the telecommunications
industry as of the effective date of this Agreement, except that any undefined
term herein shall be interpreted in accordance with the definition or its use in
the FCC Interconnection Order and the FCC Further Interconnection Order.

     1.91 "Voice Grade" means either an analog signal of 300 to 3000 Hz or a
digital signal of 56/64 kilobits per second. When referring to digital voice
grade service (a 56/64 kbps channel), the terms "DS-0" or "sub-DS-1" may also be
used.

     1.92 "Wire Center" means a building or portion thereof in which a Party has
the exclusive right of occupancy and which serves as Routing Point for Switched
Exchange Access Service.

2.0  INTERPRETATION AND CONSTRUCTION

     2.1  All references to Sections, Exhibits and Schedules shall be deemed to
be references to Sections of, and Exhibits and Schedules to, this Agreement
unless the context shall otherwise require. The headings used in this Agreement
are inserted for convenience of reference only and are not intended to be a part
of or to affect the meaning of this Agreement. Unless the context shall
otherwise require, any reference to any agreement, other instrument (including
BA or other third Party offerings, guides or practices), statute, regulation,
rule or tariff is to such agreement, instrument, statute, regulation, or rule or
tariff as amended and

                                                                              11
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

supplemented from time to time (and, in the case of a statute, regulation, rule
or tariff, to any successor provision).

     2.2  Subject to the terms set forth in Section 20 regarding rates and
charges, each Party hereby incorporates by reference those provisions of its
tariffs that govern the provision of any of the services or facilities provided
hereunder. If any provision of this Agreement and an applicable tariff cannot be
reasonably construed or interpreted to avoid conflict, the provision contained
in this Agreement shall prevail, provided that in all cases the more specific
shall prevail over the more general. If any provision contained in this main
body of the Agreement and any Schedule or Exhibit hereto cannot be reasonably
construed or interpreted to avoid conflict, the provision contained in this main
body of the Agreement shall prevail. The fact that a condition, right,
obligation, or other term appears in this Agreement but not in any such tariff
shall not be interpreted as, or be deemed grounds for finding, a conflict for
purposes of this Section 2.

3.0  SCOPE

     3.1  This Agreement sets forth the terms, conditions and pricing under
which BA and NCI will offer and provide to each other within each LATA in which
they operate within Massachusetts: i) interconnection and access to unbundled
Network Elements and ancillary services for their respective use in providing
Telephone Exchange Service; ii) resale of local Telecommunications Services; and
iii) services related to i) and ii). As such, this Agreement is an integrated
package that reflects a balancing of interests critical to the Parties. It will
be submitted to the DTE, and the Parties will refrain from requesting any action
to change, suspend or otherwise delay implementation of the Agreement.

     3.2  Subject to the terms and conditions of this Agreement, each Party
shall exercise commercially reasonable efforts to enable NCI to provide fully
operational service predominantly over its own Telephone Exchange Service
facilities to business and residential Customers in the Commonwealth of
Massachusetts. The parties agree that the performance of the terms of this
Agreement will satisfy BA's obligation to provide Interconnection under Section
251 of the Act, and the requirements of the Competitive Checklist, under Section
271 of the Act.


4.0  INTERCONNECTION PURSUANT TO SECTION 251(c)(2)

     4.1  INTERCONNECTION ACTIVATION

     NCI represents that it is, or intends to become, a provider of Telephone
Exchange Service to residential and business subscribers offered exclusively
over its own Telephone Exchange Service facilities or predominantly over its own
Telephone Exchange Service facilities in combination with the use of unbundled
Network Elements purchased from another entity and the resale of the
Telecommunications Services of other carriers.

                                                                              12
<PAGE>
 
     4.2  SCOPE OF TRAFFIC

     The types of traffic to be exchanged under this Agreement shall be Local
Traffic, IntraLATA Toll (and InterLATA Toll, as applicable) Traffic, Tandem
Transit Traffic, Meet Point Billing Traffic, and Ancillary Traffic. Subject to
the terms and conditions of this Agreement, Interconnection of the Parties
facilities and equipment for the transmission and routing of Local Traffic and
Toll Traffic pursuant to this Section 4.0 shall be established on or before the
corresponding "Interconnection Activation Date" shown for each such LATA within
the Commonwealth of Massachusetts on Schedule 3.0 and in accordance with the
terms and conditions set forth in section 10. Schedule 4.0 may be revised and
supplemented from time to time upon the mutual agreement of the Parties to
reflect additional or changed Interconnection Points in Massachusetts by
attaching one or more supplementary addenda to such Schedule.

     4.3  TRUNK TYPES AND INTERCONNECTION POINTS

          4.3.1  Section 4 describes the architecture for Interconnection of the
Parties' facilities and equipment over which the Parties shall configure the
following separate and distinct trunk groups:

     Traffic Exchange Trunks for the transmission and routing of terminating
     Local Traffic, Tandem Transit Traffic, translated LEC IntraLATA 800/888
     traffic, IntraLATA Toll Traffic, and, where agreed to between the Parties
     and as set forth in subsection 4.2.8 below, InterLATA Toll Traffic between
     their respective Telephone Exchange Service customers pursuant to Section
     251(c)(2) of the Act, in accordance with Section 5 below;

     Access Toll Connecting Trunks for the transmission and routing of Exchange
     Access traffic, including translated InterLATA 800/888 traffic, between NCI
     Telephone Exchange Service customers and purchasers of Switched Exchange
     Access Service via a BA Tandem, pursuant to Section 251(c)(2) of the Act,
     in accordance with Section 6 below;

     Information Services Trunks for the transmission and routing of terminating
     Information Services Traffic in accordance with Section 7 below;

     LSV/VCI Trunks for the transmission and routing of terminating LSV/VCI
     traffic, in accordance with Section 7 below;

     911/E911 Trunks for the transmission and routing of terminating 911/E911
     traffic, in accordance with Section 7 below;

     Directory Assistance Trunks for the transmission and routing of terminating
     directory assistance traffic, in accordance with subsection 19.4 below;

                                                                              13
<PAGE>
 
     Operator services (IntraLATA call completion) Trunks for the transmission
     and routing of terminating IntraLATA call completion traffic, in accordance
     with subsection 19.4 below; and

     Others trunks as may be requested and agreed to by the Parties.

          4.3.2  As and to the extent required by Section 251 of the Act, the
parties shall provide interconnection of their networks at any technically
feasible point. The Point of Interconnection ("POI") for the transport and
termination of traffic shall be:

     i)        at a BA end office or BA tandem for traffic terminating to BA
               customers;
     ii)       at a CLEC Central Office for traffic terminating to CLEC
               customers;
     iii)      to a Mid-Span Fiber Meet arrangement as provided in Section 4.3; 
     iv)       or any other points as mutually agreed to by the parties.

          4.3.3  The Parties shall establish interconnection points
(collectively, the "Interconnection Points" or "IPs") at the available
locations designated in Schedule 4.0. The mutually agreed-upon IPs on the NCI
network from which NCI will provide transport and termination of traffic shall
be designated as the NCI Interconnection Point(s) ("NCI-IP(s)"); the mutually
agreed-upon IPs on the BA network from which BA will provide transport and
termination of traffic shall be designated as the BA Interconnection Points 
("BA-IPs") and shall be either the BA terminating End Office serving the BA
Customer or the BA Tandem subtended by the terminating End Office.

          4.3.4  In the event either Party fails to make available a
geographically relevant End Office or functional equivalent as an IP on its
network, the other Party may, at any time, request that the first Party
establish such additional technically feasible IP(s). Such requests shall be
made as a part of the Joint Process established pursuant to subsection 10.1.
For purposes of this subsection 4.3.4, a "geographically relevant" IP shall mean
an IP that is located within the BA local calling area of equivalent BA end user
customers, but no greater than twenty five (25) miles from the BA Rate Center
Point of the BA NXX serving the equivalent relevant end user customers, or, with
the mutual agreement of the Parties, an existing and currently utilized IP
within the LATA but outside the foregoing BA local calling area and/or twenty
five (25) mile radius. "Equivalent" customers shall mean customers served by
either Party at the same physical location.

                                                                              14
<PAGE>

          4.3.5  In recognition of the large number and variety of BA-IPs
available for use by NCI, NCI's ability to select from among those points to
minimize the amount of transport it needs to provide or purchase, and the fewer
number of NCI-IPs available to BA to select from for similar purposes, NCI shall
charge BA no more than a non-distance sensitive Entrance Facility charge as
provided in Exhibit A for the transport of traffic from a BA-IP to a NCI-IP in
any given LATA.

          4.3.6  The Parties shall configure separate trunk groups (as described
in subsection 4.3.1 above) for traffic from NCI to BA, and for traffic from BA
to NCI, respectively; however, either party may at its discretion request that
the trunk groups shall be equipped as two-way trunks for testing purposes.

          4.3.7  Each Party shall make available Interconnection Points and
facilities for routing of traffic from those Interconnection Points as
designated in Schedule 4.0. Any additional traffic that is not covered in
Schedule 4.0 shall be subject to separate negotiations between the Parties,
except that (i) either Party may deliver traffic of any type or character to the
other Party for termination as long as the delivering Party pays the receiving
Party's then current Switched Exchange Access rates for such traffic, and (ii)
upon a bona fide request from either Party, the Parties will exercise all
reasonable efforts to conclude an agreement covering the exchange of such
traffic.

     4.4  PHYSICAL ARCHITECTURES

     4.4.1 NCI shall have the sole right and discretion to specify any of the
following methods for interconnection at any of the BA-lPs:

     (a)  a Physical or Virtual Collocation node NCI established at the BA-IP;
     and/or
          
     (b)  a Physical or Virtual Collocation node established separately at the
     BA-IP by a third party with whom NCI has contracted for such purposes;
     and/or

     (c)  an Entrance Facility and transport (where applicable) leased from BA
     (and any necessary multiplexing), to the BA-IP.

     4.4.2 NCI shall provide its own facilities or purchase necessary transport
for the delivery of traffic to any Collocation arrangement it establishes at a
BA-IP pursuant to Section 13.

     4.4.3 NCI may order from BA any of the Interconnection methods specified
above in accordance with the order intervals and other terms and conditions,
including, without limitation, rates and charges, set forth in this Agreement,
in any applicable Tariff(s), or as may be subsequently agreed to between the
Parties.

                                                                              15
<PAGE>

     4.4.4 BA shall have the sole right and discretion to specify any one of the
following methods for Interconnection at any of the NCI-IPs:

     (a)  upon reasonable notice to NCI, a Physical or Virtual Collocation node
     BA establishes at the NCI-IP;

     (b)  a Physical or Virtual Collocation node established separately at the
     NCI-IP by a third party with whom BA has contracted for such purposes;
     and/or

     (c)  an Entrance Facility leased from NCI (and any necessary multiplexing),
     to the NCI-IP.

     4.4.5 BA shall provide its own facilities or purchase necessary transport
for the delivery of traffic to any Collocation node it establishes at an NCI-IP
pursuant to Section 13.

     4.4.6 BA may order from NCI any of the Interconnection methods specified
above in accordance with the order intervals and other terms and conditions,
including, without limitation, rates and charges, set forth in this Agreement,
in any applicable Tariff(s), or as may be subsequently agreed to between the
Parties.

     4.4.7 Under any of the architectures described in this subsection 4.4, and
subject to mutual agreement between the Parties, either Party may utilize the
Traffic Exchange Trunks for the termination of InterLATA Toll Traffic in
accordance with the terms contained in Section 5 below and pursuant to the other
Party's Switched Exchange Access Service tariffs. The other Party's Switched
Exchange Access Service rates shall apply to such facilities.

     4.4.8 The publication "Bellcore Technical Publication GR-342-CORE; High
Capacity Digital Special Access Service, Transmission Parameter Limits and
Interface Combination" describes the specification and interfaces generally
utilized by BA and is referenced herein to assist the Parties in meeting their
respective Interconnection responsibilities.

     4.5  ALTERNATIVE INTERCONNECTION ARRANGEMENTS

     4.5.1 In addition to the foregoing methods of Interconnection, and subject
to mutual agreement of the Parties, the Parties may agree to establish a Mid-
Span Fiber Meet arrangement in accordance with the terms of this subsection 4.5,
including a SONET backbone with an electrical interface at the DS-3 level.
Nothing herein shall preclude the parties from agreeing to interconnect at a
higher speed. In the event the Parties agree to adopt a Mid-Span Fiber Meet
arrangement that utilizes both wireless and wireline facilities, each Party
agrees to bear all expenses associated with the purchase of equipment,
materials, or services necessary to facilitate and maintain such arrangement on
its side of the fiber hand-off to the other Party.

     4.5.2 The establishment of any Mid-Span Fiber Meet arrangement is expressly

                                                                              16
<PAGE>
 
conditioned upon the Parties' reaching prior written agreement on routing,
appropriate sizing and forecasting, equipment, ordering, provisioning,
maintenance, repair, testing, augment, and compensation procedures and
arrangements, reasonable distance limitations, and on any other arrangements
necessary to implement the Mid-Span Fiber Meet arrangement. Any Mid-Span Fiber
Meet arrangement requested at a third-party premises is expressly conditioned on
the Parties' having sufficient capacity at the requested location to meet such
request, on unrestricted 24-hour access for both Parties to the requested
location, on other appropriate protections as reasonably deemed necessary by
either Party, and on an appropriate commitment that such access and other
arrangements will not be changed or altered.

     4.5.3 Mid-Span Fiber Meet arrangements shall be used only for the
termination of Local Traffic and IntraLATA Toll Traffic unless and until such
time as the Parties have agreed to permit its utilization for other traffic
types and unless and until the Parties have agreed in writing on appropriate
compensation arrangements relating to the exchange of other types of traffic
over such Mid-Span Fiber Meet, and only where facilities are available.

     4.6   INTERCONNECTION IN ADDITIONAL LATAS

     4.6.1 If NCI determines to offer Telephone Exchange Services in any LATA in
Massachusetts not listed in Schedule 4.0 in which BA also offers Telephone
Exchange Services, NCI shall provide written notice to BA of the need to
establish Interconnection in such LATA pursuant to this Agreement.

     4.6.2 The notice provided in subsection 4.6.1 shall include (i) the initial
Rating Point NCI has designated in the new LATA; (ii) NCI's intended
Interconnection Activation Date; and (iii) a forecast of NCI's trunking
requirements conforming to subsection 10.4.

     4.6.3 Unless otherwise agreed to by the Parties, the Parties shall
designate the Wire Center(s) NCI has identified as its initial Rating Point(s)
in the LATA as the NCI-IP(s) in that LATA and shall designate a mutually agreed
upon Tandem Office or End Offices within the LATA nearest to the NCI-IP (as
measured in airline miles utilizing the V and H coordinates Method) as the BA-
IP(s) in that LATA, provided that, for the purpose of charging for the transport
of traffic from a BA-IP to the NCI-IP, the NCI-IP shall be no further than a
non-distance sensitive Entrance Facility away from the BA-IP.

     4.6.4 The Parties shall agree upon an addendum to Schedule 4.0 to reflect
the schedule applicable to each new LATA requested by NCI; provided, however,
that unless agreed by the Parties, the Interconnection Activation Date in a new
LATA shall not be earlier than sixty (60) days after receipt by BA of all
complete and accurate trunk orders and routing information. Within ten (10)
business days of BA's receipt of the NCI's notice provided for in 4.6.1, BA and
NCI shall confirm the BA-IP, the NCI-IP and the Interconnection Activation Date
for the new LATA by attaching an addendum to Schedule 4.0.

                                                                              17
<PAGE>
 
5.0  TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE SERVICE TRAFFIC PURSUANT TO
     SECTION 251(c)(2)

     5.1  SCOPE OF TRAFFIC

     Section 5 prescribes parameters for trunk groups (the "Traffic Exchange
Trunks") to be effected over the Interconnections specified in Section 4 for the
transmission and routing of Local Traffic, Tandem Transit Traffic, POTS-
translated LEC IntraLATA 800/888 traffic, InterLATA Toll Traffic (to the extent
applicable), and IntraLATA Toll Traffic between the Parties' respective
Telephone Exchange Service Customers.

     5.2  TRUNK GROUP CONNECTIONS AND ORDERING

          5.2.1 Traffic Exchange Trunk group connections will be made at a DS-1
level unless otherwise agreed to by the Parties. Higher speed connections shall
be made, when and where available, in accordance with the Joint Implementation
and Grooming Process prescribed in Section 10, or as may be agreed to by the
Parties.

          5.2.2 Each Party will identify its Carrier Identification Code, a
three or four digit numeric obtained from Bellcore, to the other Party when
ordering a trunk group.

          5.2.3 In the event the traffic volumes between any two Central Office
Switches at any time exceeds the CCS busy hour equivalent of one DS-1, the
Parties may, at their option, establish new one-way direct trunk groups to the
applicable End Office(s) consistent with the grade of service and quality
parameters set forth in the Joint Plan.

          5.2.4 It is expected that both Parties will make all good faith
efforts to monitor their trunk groups and to augment those groups using
generally accepted trunk engineering standards so as to not exceed blocking
objectives. The Parties agree to use modular trunk engineering techniques where
practical.

     5.3  ADDITIONAL SWITCHING SYSTEM HIERARCHY AND TRUNKING REQUIREMENTS

     For purposes of routing NCI traffic to BA, the subtending arrangements
between BA Tandem Switches and BA End Office Switches shall be the same as the
Tandem/End Office subtending arrangements BA maintains for the routing of its
own or other carriers' traffic. For purposes of routing BA traffic to NCI, the
subtending arrangements between NCI Tandem Switches (or functional equivalent)
and NCI End Office Switches (or functional equivalent) shall be the same as the
Tandem/End Office subtending arrangements (or functional equivalent) which NCI
maintains for the routing of its own or other carriers' traffic.

                                                                              18
<PAGE>
 
     5.4  SIGNALING

     Each Party will provide the other Party with access to its databases and
associated signaling necessary for the routing and completion of the other
Party's traffic in accordance with the provisions contained in Section 17 below.

     5.5  GRADES OF SERVICE

     The Parties shall initially engineer and shall jointly monitor and enhance
all trunk groups consistent with the Joint Implementation and Grooming Process
as set forth in Section 10.

     5.6  MEASUREMENT AND BILLING

          5.6.1 For billing purposes, each Party shall pass Calling Party Number
("CPN") information on each call carried over the Traffic Exchange Trunks at
such time as the originating switch is equipped for SS7 or each party shall pass
other equivalent verifiable data to the extent that the parties deploy two-way
shared trunking and that it is determined to be infeasible to pass CPN over such
trunks. At such time as either Party has the ability, as the Party receiving the
traffic, to use such CPN information to classify on an automated basis traffic
delivered by the other Party as either Local Traffic or Toll Traffic, such
receiving Party shall bill the originating Party the Local Traffic termination
rates, Intrastate Exchange Access rates, or Interstate Exchange Access rates
applicable to each minute of Traffic for which CPN is passed, as provided in
Exhibit A and applicable Tariffs.

          5.6.2 If, under the circumstances set forth in subsection 5.6.1, the
originating Party does not pass CPN on up to ten percent (10%) of calls, the
receiving Party shall bill the originating Party the Local Traffic termination
rates, Intrastate Exchange Access rates, Intrastate/Interstate Tandem Transit
Traffic rates, or Interstate Exchange Access rates applicable to each minute of
traffic, as provided in Exhibit A and applicable Tariffs, for which CPN is
passed. For the remaining up to ten percent (10%) of calls without CPN
information, the receiving Party shall bill the originating Party for such
traffic as Local Traffic termination rates, Intrastate Exchange Access rates,
Intrastate/Interstate Tandem Transit Traffic rates, or Interstate Exchange
Access rates applicable to each minute of traffic, as provided in Exhibit A and
applicable Tariffs, in direct proportion to the minutes of use of calls passed
with CPN information.

          5.6.3 If the originating Party does not pass CPN on more than ten
percent (10%) of calls, or if the receiving Party lacks the ability to use CPN
information to classify on an automated basis traffic delivered by the other
Party as either Local Traffic or Toll Traffic, and the originating Party chooses
to combine Local and Toll Traffic on the same trunk group, it will supply an
auditable Percent Local Use ("PLU") report quarterly, based on the previous
three months' traffic, and applicable to the following three months. If the
originating Party also chooses to combine Interstate and Intrastate Toll Traffic
on the same trunk group, it will supply

                                                                              19
<PAGE>
 
an auditable Percent Interstate Use ("PIU") report quarterly, based on the
previous three months' terminating traffic, and applicable to the following
three months. In lieu of the foregoing PLU and/or PIU reports, the Parties may
agree to provide and accept reasonable surrogate measures for an agreed-upon
interim period.

          5.6.4 Measurement of billing minutes for purposes of determining
terminating compensation shall be in conversation seconds.

     5.7  RECIPROCAL COMPENSATION ARRANGEMENTS - SECTION 251(B)(5)

     Reciprocal Compensation arrangements address the transport and termination
of Local Traffic. BA's delivery of Traffic to NCI that originated with a third
carrier is addressed in subsection 7.3. Where NCI delivers Traffic (other than
Local Traffic) to BA, except as may be set forth herein or subsequently agreed
to by the Parties, NCI shall pay BA the same amount that such carrier would have
paid BA for termination of that Traffic at the location the Traffic is delivered
to BA by NCI. Compensation for the transport and termination of traffic not
specifically addressed in this subsection and shall be as provided elsewhere in
this Agreement, or if not so provided, as required by the Tariffs of the Party
transporting and/or terminating the traffic.

          5.7.1 Nothing in this Agreement shall be construed to limit either
Party's ability to designate the areas within which that Party's Customers may
make calls which that Party rates as "local" in its Customer Tariffs.

          5.7.2 The Parties shall compensate each other for the transport and
termination of Local Traffic in an equal and symmetrical manner at the rates
provided in the Detailed Schedule of Itemized Charges (Exhibit A hereto), as may
be amended from time to time in accordance with Exhibit A and subsection 20.1.2
below or, if not set forth therein, in the applicable Tariff(s) of the
terminating Party, as the case may be. These rates are to be applied at the NCI-
IP for traffic delivered by BA, and at the BA-IP for traffic delivered by NCI.
No additional charges, including port or transport charges, shall apply for the
termination of Local Traffic delivered to the BA-IP or the NCI-IP, except as set
forth in Exhibit A. When Local Traffic is terminated over the same trunks as
Toll Traffic, any port or transport or other applicable access charges related
to the delivery of Toll Traffic from the IP to an end user shall be prorated to
be applied only to the Toll Traffic.

                5.7.2.1 Each Party will pay to the other Party a blended
reciprocal compensation rate as specified in Exhibit A for Reciprocal
Compensation Traffic delivered to the other Party's IP in each LATA.

          5.7.3 The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all Toll Traffic shall continue to be governed by
the terms and conditions of the applicable federal and state Tariffs. Similarly,
the reciprocal compensation arrangements contained in this

                                                                              20
<PAGE>
 
subsection 5.7 shall not apply to traffic handed off from one Party to the other
Party for delivery to an Internet Service Provider ("ISP") for carriage over the
Internet except where and to the extent that the FCC, the DTE, or a court of
competent jurisdiction orders otherwise; provided, however, that BA shall
compensate NCI on the same basis as other Massachusetts CLECs pursuant to its
commitment in DTE 97-116, for as long as such compensation is paid to
Massachusetts CLECs generally. BA may designate one or more NCI NXX(s) for End
Office rate treatment and may chose to route Reciprocal Compensation Traffic to
such NXX(s) over dedicated trunk(s). NCI shall provide BA a choice of delivering
such traffic to either (i) the single IP serving that NXX or (ii) an IP
established by NCI within the Rate Center Area of the designated NXX(s) for
delivery of such traffic by BA. Any such trunk may carry traffic for more than
one such designated NXX(s). For any Reciprocal Compensation Traffic routed over
such dedicated trunks, BA may elect to pay NCI at the effective End Office
Termination rate.

          5.7.4 Compensation for transport and termination of all Traffic which
has been subject to performance of INP by one Party for the other Party pursuant
to Section 14 shall be as specified in subsection 14.5.

          5.7.5 The designation of Traffic as Local or non-Local for purposes of
compensation shall be based on the actual originating and terminating points of
the complete end-to-end call, regardless of the entities involved in carrying
any segment of the call.

          5.7.6 Each Party reserves the right to measure and audit all Traffic,
up to a maximum of two audits per calendar year, to ensure that proper rates are
being applied appropriately, provided, however, that either Party shall have the
right to conduct additional audit(s) if the preceding audit disclosed material
errors or discrepancies. Each Party agrees to provide the necessary Traffic data
or permit the other Party's recording equipment to be installed for sampling
purposes in conjunction with any such audit.

                                                                              21
<PAGE>
 
6.0  TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC PURSUANT TO 251(c)(2)

     6.1  SCOPE OF TRAFFIC

     Section 6 prescribes parameters for certain trunks to be established over
the Interconnections specified in Section 4 for the transmission and routing of
traffic between NCI Telephone Exchange Service Customers and Interexchange
Carriers ("Access Toll Connecting Trunks"), in any case where NCI elects to have
its End Office Switch subtend a BA Tandem. This includes casually-dialed 
(1010XXX and 101XXXX) traffic.

     6.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING

          6.2.1 NCI shall establish Access Toll Connecting Trunks by which it
will provide tandem-transported Switched Exchange Access Services to
Interexchange Carriers to enable such Interexchange Carriers to originate and
terminate traffic to and from NCI's Customers.

          6.2.2 Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access to allow NCI's Customers to connect
to or be connected to the interexchange trunks of any Interexchange Carrier
which is connected to a BA Tandem.

          6.2.3 The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch NCI utilizes to provide Telephone Exchange
Service and Switched Exchange Access in a given LATA to a Tandem BA utilizes to
provide Exchange Access in such LATA.

          6.2.4 The Parties shall jointly determine which BA Tandem(s) will be
sub-tended by each NCI End Office Switch. NCI's End Office switch shall sub-tend
the BA Tandem that would have served the same rate center on BA's network.

     6.3  MEET-POINT BILLING ARRANGEMENTS

          6.3.1 NCI and BA will establish Meet-Point Billing arrangements in
order to provide a common transport option to Switched Access Services Customers
via a Tandem Switch in accordance with the Meet-Point Billing guidelines
contained in the OBF's MECAB and MECOD documents, except as modified herein, and
in BA's applicable Switched Access Service tariffs. The arrangements described
in this Section 6 are intended to be used to provide Switched Exchange Access
Service that originates and/or terminates on a Telephone Exchange Service that
is provided by either Party, where the transport component of the Switched
Exchange Access Service is routed through a Tandem Switch that is provided by
BA.

          6.3.2 In each LATA, the Parties shall establish MPB arrangements
between the applicable Rating Point/BA Serving Wire Center combinations.

                                                                              22
<PAGE>
 
          6.3.3 Interconnection for the MPB arrangement shall occur at the BA-IP
in the LATA, unless otherwise agreed to by the Parties.

          6.3.4 NCI and BA will use reasonable efforts, individually and
collectively, to maintain provisions in their respective state access tariffs,
and/or provisions within the National Exchange Carrier Association ("NECA")
tariff No. 4, or any successor Tariff sufficient to reflect the MPB arrangements
established pursuant to this Agreement.

          6.3.5 Each Party shall implement the "Multiple Bill/Single Tariff" or
"Multiple Bill/Multiple Tariff" option, as appropriate, in order to bill an IXC
for the portion of the jointly provided telecommunications service provided by
that Party or each party may use the New York State Access Pool on their behalf
to implement "Single Bill/Multiple Tariff or Single Bill/Single Tariff option,
as appropriate, in order to bill an IXC for the portion of the jointly provided
telecommunications service provided by each Party. In general, there are four
alternative Meet-Point Billing arrangements possible, which are:

     1)        Single bill, single tariff in which a single bill is presented to
          the Interexchange Carrier and each Local Exchange Carrier involved
          applies rats for its portion of the services from the same tariff.

     2)        Multiple bill, single tariff in which each involved Local
          Exchange Carrier presents separate bills to the Interexchange Carrier
          and each carrier involved applies rates for its portion of the service
          from the same tariff.

     3)        Multiple bill, multiple tariff in which each involved Local
          Exchange Carrier presents separate bills to the Interexchange Carrier,
          and each carrier involved applies rates for its portion of the service
          from its own unique tariff, and

     4)        Single bill/multiple tariff shall mean that one bill is rendered
          to an Interexchange Carrier from all LECs who are jointly providing
          Switched Exchange Access Service. A single bill consists of all rate
          elements applicable to access services billed on one statement of
          charges under one bill account number using each LECs appropriate
          access tariffs. The bill could be rendered by, or on behalf of, any of
          the Local Exchange Carriers involved in the provision of service.

          6.3.6 The rate elements to be billed by each Party are as set forth in
Schedule 6.3. The actual rate values for each Party's affected access service
rate element shall be the rates contained in that Party's own effective federal
and state access tariffs, or other document that contains the terms under which
that Party's access services are offered. The MPB billing percentages for each
Rating Point/BA Serving Wire Center combination shall be calculated in
accordance with the formula set forth in subsection 6.3.17 below.

          6.3.7 Each Party shall provide the other Party with the billing name,
billing address, and Carrier Identification Code ("CIC") of the IXC, and
identification of the IXC's Local Serving Wire Center in order to comply with
the MPB notification process as outlined in the MECAB document via facsimile or
such other media as the Parties may agree to.

                                                                              23
<PAGE>
 
          6.3.8  BA shall provide NCI with the Switched Access Detail Usage Data
(category 1101XX records) on magnetic tape or via such other media as the
Parties may agree to, no later than ten (10) business days after the date the
usage occurred.

          6.3.9  NCI shall provide BA with the Switched Access Summary Usage
Data (category 1150XX records) on magnetic tape or via such other media as the
Parties may agree, no later than ten (10) business days after the date of its
rendering of the bill to the relevant IXC, which bill shall be rendered no less
frequently than monthly.

          6.3.10 All usage data to be provided pursuant to subsections 6.3.8 and
6.3.9 above shall be sent to the following addresses:

     To NCI:        Nathaniel Morse, President      
                    Norfolk County Internet, Inc.   
                    Unit 12A Depot Plaza            
                    13-25 Main Street               
                    Franklin, MA 02038               

     To BA:         New York State Access Pool          
                    C/O ACM                             
                    1309 Main Street                    
                    Rotterden Junction, NY 12150        
                    Attn: Mark Ferri                     

Either Party may change its address for receiving usage data by notifying the
other Party in writing pursuant to subsection 29.10.

          6.3.11 Each Party shall coordinate and exchange the billing account
reference ("BAR") and billing account cross reference ("BACR") numbers or
Operating Company Number ("OCN"), as appropriate, for the MPB Service. Each
Party shall notify the other if the level of billing or other BAR/BACR elements
change, resulting in a new BAR/BACR number, or if the OCN changes.

          6.3.12 Errors may be discovered by NCI, the IXC or BA. Each Party
agrees to provide the other Party with notification of any errors it discovers
within two (2) business days of the date of such discovery. In the event of a
loss of data, both Parties shall cooperate to reconstruct the lost data and, if
such reconstruction is not possible, shall accept a reasonable estimate of the
lost data based upon prior usage data.

          6.3.13 Either Party may request a review or audit of the various
components of access recording up to a maximum of two (2) audits per calendar
year. All costs associated with each review and audit shall be borne by the
requesting Party. Such review or audit shall be

                                                                              24
<PAGE>
 
conducted subject to confidentiality protection and during regular business
hours. A Party may conduct additional audits, at its expense, upon the other
Party's consent, which consent shall not be unreasonably withheld.

          6.3.14 Nothing contained in this subsection 6.3 shall create any
liability for damages, losses, claims, costs, injuries, expenses or other
liabilities whatsoever on the part of either Party (other than as may be set
forth in MECAB or in any applicable Tariff).

          6.3.15 The Parties shall not charge one another for the services
rendered or information provided pursuant to this subsection 6.3.

          6.3.16 MPB will apply for all traffic bearing the 500, 900, 800/888
(to the extent provided by an IXC) or any other non-geographic NPA which may be
likewise designated for such traffic in the future.

          6.3.17 In the event NCI determines to offer Telephone Exchange
Services in another LATA in which BA operates a Tandem Switch, BA shall permit
and enable NCI to subtend the BA Tandem Switch(es) designated for the BA End
Offices in the area where the NCI Rating Point(s) associated with the NPA-NXX(s)
to/from which the Switched Exchange Access Services are homed. The MPB billing
percentages for each new Routing Point/BA Serving Wire Center combination shall
be calculated according to the following formula:

                     a / (a + b) = NCI Billing Percentage
                                      and
                      b / (a + b) = BA Billing Percentage

               where:
               -----
               a = the airline mileage between the Routing Point and the actual
          point of interconnection for the MPB arrangement; and

               b = the airline mileage between the BA Serving Wire Center and
          the actual point of interconnection for the MPB arrangement.

          NCI shall inform BA of the LATA in which it intends to offer Telephone
Exchange Services and its calculation of the billing percentages which should
apply for such arrangement, as part of the notice required by subsection 4.4.1
above. Within ten (10) business days of NCI's delivery of notice to BA, BA and
NCI shall confirm the new Routing Point/BA Serving Wire Center combination and
billing percentages.

          6.3.18 Within thirty (30) days of a request by NCI, BA agrees to
notify all switched access users with a Carrier Identification Code in a LATA in
which the Parties have newly established Interconnection arrangements pursuant
to this Agreement that BA and NCI have entered in a Meet Point Billing
arrangement.

     6.4  800/888 TRAFFIC

                                                                              25
<PAGE>
 
     The following terms shall apply when either Party delivers 800/888 calls to
the other Party for completion.

          6.4.1 When NCI delivers translated 800/888 calls to BA for completion
     (a)  to an IXC, NCI shall:
          (i)   Provide a MPB record in an industry standard format to BA; and
          (ii)  Bill the IXC the appropriate NCI query charge associated with
          the call.
     (b)  as an IntraLATA call to BA or another LEC in the LATA, NCI shall:
          (i)   Provide a copy record in an industry standard format to BA or
          the terminating LEC;
          (ii)  The orginating party shall bill the terminating party for the
          delivery of the 800/888 traffic at the rates set forth in Exhibit A.
          The terminating Party shall not bill the originating party the 800/888
          rates set forth in Exhibit A under this agreement.

          6.4.2 When BA delivers translated 800/888 calls originated by BA's or
another LEC's Customers to NCI for completion
     (a)  to NCI in its capacity as an IXC, BA shall:
          (i)   Bill NCI the appropriate BA query charge associated with the
          call; and
          (ii)  Bill NCI the appropriate FGD Exchange Access charges associated
          with the call.
     (b)  as an IntraLATA call to NCI in its capacity as a LEC,
                (i)           The orginating party shall bill the terminating
                     party for the delivery of the 800/888 traffic at the rates
                     set forth in Exhibit A. The terminating party shall not
                     bill the originating party the 800/888 rates set forth in
                     Exhibit A under this agreement.
                (ii)          The originating party shall provide a copy record
                     in an industry standard format to NCI.

7.0  TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC

     7.1  INFORMATION SERVICES TRAFFIC

     The following provisions shall apply only to NCI-originated Information
Services Traffic directed to an information services platform connected to BA's
network. At such time as NCI connects Information Services platforms to its
network, the Parties shall agree upon a comparable arrangement for BA-originated
Information Services Traffic. The Information Services Traffic subject to the
following provisions is switched voice traffic, delivered to service providers
who offer recorded announcement information or open discussion information
programs to the general public; it is not Internet traffic.

          7.1.1  NCI shall have the option to route Information Services Traffic
that originates on its own network to the appropriate information services
platform(s) connected to

                                                                              26
<PAGE>
 
BA's network. In the event NCI exercises such option, NCI will establish a
dedicated trunk group to the BA information services serving switch. This trunk
group will be utilized to allow NCI to route information service traffic
originated on its network to BA.

     Where NCI serves a Customer through the purchase of a BA unbundled Port
Element, information service traffic from that Customer may be routed over BA
information service trunks on a shared basis.

          7.1.2 Nothing in this Agreement shall restrict either Party from
offering, or obviate either Party's obligations, if any, under Applicable Laws,
to offer to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

          7.1.3 For calls to variable rated information services (e.g., NXX 550,
976, 940 as applicable), the Parties shall agree to implement either of two
separate billing arrangements, as set forth in Schedule 7.1.3. Under either
arrangement, NCI shall bill and collect information services provider charges
from its Customers. BA shall charge NCI, and the parties shall exchange call
detail information and handle adjustments, according to the terms set forth in
the agreed upon billing arrangement, at customer usage detail rates specified in
Exhibit A. Applicable information shall be provided in as timely a fashion as
practical in order to facilitate record review and reflect actual prices set by
the individual information services providers. The same billing arrangements
shall apply whether NCI services its Customer from switching facilities outside
the BA network, or from BA Local Switching Elements, and agreement to mutually
support one or the other billing arrangement shall precede interconnection of
the NCI network to the appropriate information services platform(s) connected to
BA's network. BA may require reasonable demonstration, as defined in the
applicable billing arrangement, that the agreed upon arrangement has been
implemented by NCI prior to establishing such interconnection.

          7.1.4 Where BA agrees to accept adjustments from NCI for calls
originated by NCI Customers to information services platform(s) connected to
BA's network, NCI shall follow the same policy in allowing adjustments to its
Customers as BA follows with its own Customers. NCI shall provide to BA
sufficient information regarding uncollectibles and Customer adjustments to
allow BA to pass through the adjustments to the information services provider,
and BA shall pass through such adjustments. However, if the information services
provider disputes such adjustments and refuses to accept such adjustments, NCI
shall reimburse BA for all such disputed adjustments. Final resolution regarding
all disputed adjustments shall be solely between NCI and the information
services provider.

          7.1.5 The Information Services Traffic addressed herein does not
include 555 traffic or similar traffic with AIN service interfaces, which
traffic shall be subject to separate arrangements between the Parties.

                                                                              27
<PAGE>
 
     7.2  INTENTIONALLY LEFT BLANK

7.3  TANDEM TRANSIT SERVICE ("TRANSIT SERVICE")

          7.3.1 "Transit Service" means the delivery of certain traffic between
NCI and another Local Exchange Carrier by BA over the Telephone Exchange Service
Trunks, where both carriers' End Offices subtend a BA tandem. The following
traffic types will be delivered: (i) Local Traffic or IntraLATA Toll originated
from NCI to such LEC and (ii) Local or IntraLATA Toll Traffic originated from
such LEC and terminated to NCI where BA carries such traffic pursuant to the
Commission's primary toll carrier plan or other similar plan.

          7.3.2 Subject to Section 7.3.4, the Parties shall compensate each
other for Transit Service as follows:

          (a)  NCI shall pay BA for Local Traffic that NCI originates over the
               Transit Service at the rate specified in Pricing Schedule plus
               any additional charges or costs such terminating LEC imposes or
               levies on BA for the delivery or termination of such traffic,
               including any switched access charges; and

          (b)  BA shall pay NCI for Local or IntraLATA Toll Traffic terminated
               to NCI from such LEC at the appropriate reciprocal compensation
               rates described in Section 5.7, or (where BA delivers such
               traffic pursuant to the Commission's primary toll carrier plan or
               other similar plan) at NCI's applicable switched access rates,
               whichever is appropriate.

          7.3.3 BA expects that all networks involved in Tandem Transit Traffic
will deliver each call to each involved network with CCS and the appropriate
Transactional Capabilities Application Part ("TCAP") message to facilitate full
interoperability of those CLASS Features supported by BA and billing functions.
In all cases, each Party shall follow the Exchange Message Interface ("EMI")
standard and exchange records between the Parties and with the and the
terminating carrier to facilitate the billing process to the originating
network.

          7.3.4 Each Party shall exercise all reasonable efforts to enter into a
reciprocal local traffic exchange arrangement (either via written agreement or
mutual tariffs) with any wireless carrier, ITC, NCI or other LEC to which it
sends, or from which it receives, local traffic that transits the other Party's
facilities over Traffic Exchange Trunks. Each Party will, upon request, provide
the other Party with all reasonable cooperation and assistance in obtaining such
arrangements. If either Party fails to enter into such an arrangement as quickly
as commercially reasonable following the Effective Date and to provide written
notification of such Agreement, including the relevant rates therein, to the
other Party, but continues to utilize the other Party's Transit Service for the
exchange of local traffic with such wireless carrier, ITC, NCI, or other LEC,
then the Party utilizing the Transit Service shall, in addition to paying the
rate set forth in

                                                                              28
<PAGE>
 
Exhibit A for said Transit Service, pay the other Party any charges or costs
such terminating third party carrier imposes or levies on the other Party for
the delivery or termination of such Traffic, including any switched access
charges, plus all reasonable expenses incurred by the other Party in delivering
         ----
or terminating such Traffic and/or resulting from the utilizing Party's failure
to secure said reciprocal local traffic exchange arrangement. In addition,
neither Party shall take any actions to prevent the other Party from entering
into a direct and reciprocal local traffic exchange arrangement (either via
\written agreement or mutual tariffs) with any wireless carrier, ITC, NCI, or
other LEC to which it sends, or from which it receives, local traffic that does
not utilize the Transit Service of the first Party. The Parties agree to work
cooperatively in appropriate industry fora to promote the adoption of reasonable
industry guidelines relating to Tandem Transit Traffic.

          7.3.5  Tandem Transit Traffic shall be routed over the Traffic
Exchange Trunks described in Section 5 above.

     7.4  911/E911 ARRANGEMENTS

          7.4.1  NCI may, at its option, interconnect to the BA 911/E911
selective routers or 911 Tandem Offices, as appropriate, that serve the areas in
which NCI provides Telephone Exchange Services, for the provision of 911/E911
services and for access to all subtending Public Safety Answering Points
("PSAP"). In such situations, BA will provide NCI with the appropriate CLLI
codes and specifications of the Tandem Office serving area. In areas where E911
is not available, NCI and BA will negotiate arrangements to connect NCI to the
911 service.

          7.4.2  Path and route diverse interconnections for 911/E911 shall be
made at the NCI-IP, the BA-IP, or other points as necessary and mutually agreed,
and as required by law or regulation.

          7.4.3  Within thirty (30) days of its receipt of a request from NCI
and to the extent authorized by the relevant federal, state, and local
authorities, BA will provide NCI with the following at no charge:

          (a)    a file on diskette or other mutually agreed upon medium
containing the Master Street Address Guide ("MSAG") for each county within the
LATA(s) specified in this Agreement, which MSAG shall be updated no more
frequently than monthly and a complete copy of which shall be made available on
an annual basis;

          (b)    a list of the address, CLLI code, and an associated NXX of each
911/E911 selective router or 911 Tandem office(s) in the area in which NCI
plans to offer Telephone Exchange Service;

          (c)    a list of the address, contact name and phone number of each
PSAP in the BA serving area in which NCI plans to offer Telephone Exchange
Service;

          (d)    a list of BA personnel who currently have 911 responsibility;

          (e)    any special 911 trunking requirements for each 911/E911
selective router

                                                                              29
<PAGE>
 
or 911 Tandem;

          (f)    an electronic interface, when available, through which NCI
shall input and provide a daily update of 911 /E911 database information
related to appropriate NCI Customers. All customer related 911 data exchanged
electronically shall conform to the National Emergency Number Association
standards;

          (g)    return of any NCI E911 data entry files containing errors, so
that NCI may ensure the accuracy of the Customer records; and

          (h)    a Design Layout Record ("DLR") of a 911 (CAMA) trunk, if
applicable.

          7.4.4  In cases where a Customer of one Party elects to discontinue
its service and become the Customer of the other Party ("Party B") but desires
to retain its original telephone number pursuant to an INP arrangement, Party B
will outpulse the telephone number to which the call has been forwarded (i.e.
                                                                         --- 
the Customer's ANI) to the 911 Tandem Office. Party B will also provide the 911
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          7.4.5  BA and NCI will use their best efforts to facilitate the
prompt, robust, reliable and efficient interconnection of NCI systems to the 911
/E911 platforms.

          7.4.6  BA and NCI will work cooperatively to arrange meetings with
PSAPs to answer any technical questions the PSAPs, or county or municipal
coordinators may have regarding the 911/E911 arrangements.

          7.4.7  The Parties acknowledge that the provision of INP, until LNP
with full 911 compatibility is available, creates a special need to have the
Automatic Location Identification ("ALI") screen reflect two numbers: the "old"
number and the "new" number assigned by NCI. The Parties acknowledge further the
objective of including the five character NENA Telephone Company Identification
("TCI") of the company that provides service to the calling line as part of the
ALI display.

          7.4.8  NCI will compensate BA for connections to its 911/E911 pursuant
to Exhibit A. NCI will comply with all applicable rules and regulations,
(INCLUDING 911 taxes and surcharges) pertaining to the provision of 911/E911
services in Massachusetts.

          7.4.9  NCI will document/verify that they can enter data into the 911
database under the NENA Standards for LNP. This includes but is not limited to
using their NENA ID to lock and unlock records and the posting of their NENA ID
to the ALI record.

8.0  NUMBER RESOURCES, RATE CENTERS AND RATING POINTS

     8.1  Nothing in this Agreement shall be construed to limit or otherwise
adversely affect in any manner either Party's right to employ or to request and
be assigned any Central Office (NXX) Codes pursuant to the Central Office Code
Assignment Guidelines, as may be

                                                                              30
<PAGE>
 
amended from time to time, or to establish, by Tariff or otherwise, Rate Centers
and Rating Points corresponding to such NXX codes. Until such time as number
administration is provided by a third party, BA shall provide NCI access to
telephone numbers by assigning NXX codes to NCI in accordance with such
Assignment Guidelines.

     8.2  It shall be the responsibility of each Party to program and update its
own switches and network systems in accordance with the Local Exchange Routing
Guide ("LERG") in order to recognize and route traffic to the other Party's
assigned NXX codes at all times. Neither Party shall impose any fees or charges
whatsoever on the other Party for such activities, except as expressly set forth
in this Agreement.

     8.3  Unless mandated otherwise by a Commission order, the Rate Center Areas
will be the same for each Party. During the term of this Agreement, NCI shall
adopt the Rate Center Areas and Rate Center Points that the Commission has
approved for BA, in all areas where BA and NCI service areas overlap, and NCI
shall assign whole NPA-NXX codes to each Rate Center unless the LEC industry
adopts alternative methods of utilizing NXXs in the manner adopted by the NANP.

     8.4  NCI will also designate a Rating Point for each assigned NXX code. NCI
shall designate one location for each Rate Center Area as the Rating Point for
the NPA-NXXs associated with that Area, and such Rating Point shall be within
the same LATA as the Rate Center Area but not necessarily within the Rate Center
Area itself.

     8.5  Notwithstanding anything to the contrary contained herein, nothing in
this Agreement is intended to, and nothing in this Agreement shall be construed
to, in any way constrain NCI's choices regarding the size of the local calling
area(s) that NCI may establish for its Customers, which local calling areas may
be larger than, smaller than, or identical to, BA's local calling areas.

9.0  NETWORK MAINTENANCE AND MANAGEMENT; OUTAGES

     9.1  COOPERATION

     The Parties will work cooperatively to install and maintain a reliable
network. NCI and BA will exchange appropriate information (e.g., maintenance
                                                           ----
contact numbers, escalation procedures, network information, information
required to comply with law enforcement and other security agencies of the
Government) to achieve this desired reliability. In addition, the Parties will
work cooperatively to apply sound network management principles to alleviate or
to prevent congestion.

     9.2  RESPONSIBILITY FOR FOLLOWING STANDARDS

     Each Party recognizes a responsibility to follow the standards that may be
agreed to

                                                                              31
<PAGE>
 
between the Parties and to employ characteristics and methods of operation that
will not interfere with or impair the service or any facilities of the other or
any third parties connected with or involved directly in the network of the
other.

     9.3  INTERFERENCE OR IMPAIRMENT

     If Bell Atlantic reasonably determines that the characteristics and methods
of operation used by NCI will or is likely to interfere with or impair its
provision of services, BA shall have the right to discontinue service subject,
however, to the following:

          9.3.1  BA shall have given NCI at least ten (10) days' prior written
notice of the interference or impairment or potential interference or impairment
and the need to correct the condition within said time period.

          9.3.2  BA shall have concurrently provided a copy of the notice
provided to NCI under (9.3.1) above to the appropriate federal and/or state
regulatory bodies.

          9.3.3  Notice in accord with subsections 9.3.1 and 9.3.2 above shall
not be required in emergencies and BA may immediately discontinue service if
reasonably necessary to meet its obligations. In such case, however, BA shall
use all reasonable means to notify NCI and the appropriate federal and/or state
regulatory bodies.

          9.3.4  Upon correction of the interference or impairment, BA will
promptly renew service to NCI. During such period of discontinuance, there will
be no compensation or credit allowance by BA to NCI for interruptions.

     9.4  REPEATED OR WILLFUL NONCOMPLIANCE

     The Interconnection, unbundled Network Elements, and services provided
hereunder may be discontinued by either Party upon thirty (30) days written
notice to the other for repeated or willful violation of and/or a refusal to
comply with this Agreement in any material respect. The Party discontinuing will
notify the appropriate federal and/or state regulatory bodies concurrently with
the notice to the other Party of the prospective discontinuance.

     9.5  OUTAGE REPAIR STANDARD

     In the event of an outage or trouble in any arrangement, facility, or
service being provided by a Party hereunder, the providing Party will follow
procedures for isolating and clearing the outage or trouble that are no less
favorable than those that apply to comparable arrangements, facilities, or
services being provided by the providing Party to any other carrier whose
network is connected to that of the providing Party. NCI and BA may agree to
modify those procedures from time to time based on their experience with
comparable Interconnection arrangements with other carriers.

                                                                              32
<PAGE>
 
     9.6  NOTICE OF CHANGES - SECTION 251(C)(5)

     If a Party makes a change in the information necessary for the transmission
and routing of services using that Party's network, or any other change in its
network which it believes will materially affect the inter-operability of its
network with the other Party's network, the Party making the change shall
provide at least ninety (90) days advance written notice of such change to the
other Party. In addition, the Parties will comply with the Network Disclosure
rules adopted by the FCC in CC Docket No. 86-79 as may be amended from time to
time.

     9.7  FRAUD

     The Parties shall work cooperatively to minimize fraud associated with
third-number billed calls, calling card calls, and any other services related to
this Agreement.

10.0 JOINT NETWORK CONFIGURATION AND GROOMING PROCESS; AND INSTALLATION,
     MAINTENANCE, TESTING AND REPAIR.

     10.1 JOINT NETWORK CONFIGURATION AND GROOMING PROCESS

     Upon request of either Party, the Parties shall jointly develop an
implementation and grooming process (the "Joint Grooming Process" or "Joint
Process") which may define and detail, inter alia,
                                       ----- ----
     (a)  agreement on Physical Architecture consistent with the guidelines
          defined in Section 4.0;

     (b)  standards to ensure that Interconnection trunk groups experience a
          grade of service, availability and quality which is comparable to that
          achieved on interoffice trunks within BA's network and in accord with
          all appropriate relevant industry-accepted quality, reliability and
          availability standards;

     (c)  the respective duties and responsibilities of the Parties with respect
          to the administration and maintenance of the trunk groups, including
          but not limited to standards and procedures for notification and
          discoveries of trunk disconnects;

     (d)  disaster recovery provision escalations;

     (e)  additional technically feasible IP(s) in a LATA as provided in Section
          4.0 above; and

     (f)  such other matters as the Parties may agree, including e.g., End 
                                                                 ----
          Office to End Office high usage trunks as good engineering practices
          may dictate.

                                                                              33
<PAGE>
 
The initial mutual Interconnection is not dependent upon completion of the Joint
Grooming Process.

     10.2   INSTALLATION, MAINTENANCE, TESTING AND REPAIR

     Unless otherwise agreed to by the Parties, Interconnection shall be
provided at parity. For purposes of this Agreement, a Party's obligation to
provide parity shall be in accordance with Applicable Laws. If either Party is
unable to fulfill its obligations under this subsection 10.2, it shall notify
the other Party of its inability to do so and will negotiate alternative
intervals in good faith. The Parties agree that the standards to be used by each
Party for isolating and clearing any disconnections and/or other outages or
troubles shall be at parity.

     10.3   NETWORK RELIABILITY COUNCIL

     The Parties will carefully review the Network Reliability Council's
recommendations and, as part of the Joint Grooming Plan, implement such
recommendations where technically and economically feasible.

     10.4   FORECASTING REQUIREMENTS FOR TRUNK PROVISIONING

     Within ninety (90) days of executing this Agreement, each Party shall
provide the other Party a one (1) year traffic forecast. This initial forecast
will provide the amount of traffic to be delivered to BA over each of the
Traffic Exchange Trunk groups over the next four (4) quarters. The forecast
shall be updated and provided to BA on an as-needed but no less frequently than
quarterly. All forecasts shall include Access Carrier Terminal Location (ACTL),
traffic type (local/toll, operator services, 911, etc.), code (identifies trunk
group), A location/Z location (CLLI codes for NCI-IPs and BA-IPs, interface type
(e.g., DS1), and trunks in service each year (cumulative).
 ----

     10.4.1 Trunk Provisioning Pursuant to Forecasts. Because BA's trunking 
requirements will be dependent on the Customer segments and service segments
within Customer segments to whom NCI decides to market its services, BA will be
dependent on NCI to provide accurate trunk forecasts for both inbound (from BA)
and outbound (from NCI) traffic. BA will, as an initial matter and upon request,
provide the same number of trunks to terminate local traffic to NCI as NCI
provides to terminate local traffic to BA, unless NCI expressly identifies
particular situations that are expected to produce traffic that is substantially
skewed in either the inbound or outbound direction, in which case BA will
provide the number of trunks NCI suggests; provided, however, that in all cases
BA's provision of the forecasted number of trunks to NCI is conditioned on the
following: that such forecast is based on reasonable engineering criteria, there
are no capacity constraints, and NCI's previous forecasts have proven to be
reliable and accurate.

     10.4.2 Monitoring and Adjusting Forecasts. BA will, for ninety (90) days,
monitor

                                                                              34
<PAGE>
 
traffic on each trunk group that it establishes at NCI's suggestion or request
pursuant to the procedures identified in subsection 10.4.1 above. At the end of
such ninety (90) day period, BA may disconnect trunks that, based on reasonable
engineering criteria and capacity constraints, are not warranted by the actual
traffic volume experienced. If, after such initial ninety (90) day period for a
trunk group, BA determines that any trunks in the trunk group in excess of four
(4) DS-1s are not warranted by actual traffic volumes (considering engineering
criteria for busy hour CCS and blocking percentages), then BA may hold NCI
financially responsible for the excess facilities. In subsequent periods, BA may
also monitor traffic for ninety (90) days on additional trunk groups that NCI
suggests or requests BA to establish. If., after any such (90) day period, BA
determines that any trunks in the trunk group are not warranted by actual
traffic volumes (considering engineering criteria for busy hour call seconds and
blocking percentages), then BA may hold NCI financially responsible for the
excess facilities. At any time during the relevant ninety (90) day period, NCI
may request that BA disconnect trunks to meet a revised forecast. In such
instances, BA may hold NCI financially responsible for the disconnected trunks
retroactive to the start of the ninety (90) day period through the date such
trunks are disconnected.

     10.4.3  Reciprocal Responsibility. To the extent that BA requires NCI to
install trunks for delivery of traffic to BA, NCI may apply the same procedures
with respect to BA's trunking requirements.

     10.5    DEMAND MANAGEMENT FORECASTS

     10.5.1  NCI will furnish BA with good faith demand management forecasts to
enable BA to effectively plan its network infrastructure and work force levels
to accommodate anticipated NCI demand for BA services and products. Such
forecasts will describe NCI's expected needs for service volumes, and timeframes
for service deployment, by wire center. NCI agrees to provide such forecasts to
BA thirty (30) days following the Effective Date, with updates to follow every
six months thereafter. BA agrees that such forecasts shall be subject to the
confidentiality provisions defined in subsection 29.4 below, and that such
information will only be used by BA to provide Interconnection pursuant to this
Agreement.

11.0 UNBUNDLED ACCESS - SECTION 251(C)(3)

     To the extent required of each Party by Section 251 of the Act, each Party
shall offer to the other Party nondiscriminatory access to Network Elements on
an unbundled basis at any technically feasible point. BA shall unbundle and
separately price and offer Network Elements such that NCI will be able to lease
and interconnect to whichever of the Network Elements NCI requires, and to allow
NCI to combine the BA-provided elements with any facilities and services that
NCI may itself provide, except that NCI shall not recombine Network Elements
purchased from BA for use as a substitute for the purchase at wholesale rates of
Telecommunications Services that BA provides unless otherwise mandated by the
FCC or the Commission or agreed to by BA with other carriers. Any combination by
NCI of unbundled Network Elements purchased from BA shall be through a
Collocation arrangement pursuant to Section 13.0.

                                                                              35
<PAGE>
 
     11.1  AVAILABLE NETWORK ELEMENTS

     At the request of NCI, BA shall provide NCI access to the following
unbundled Network Elements in accordance with the requirements of the FCC
Regulations:

           11.1.1  Local Loops, as set forth in subsection 11.2;

           11.1.2  The Network Interface Device;

           11.1.3  Switching Capability, as set forth in subsection 11.3;

           11.1.4  Interoffice Transmission Facilities, as set forth in
                   subsection 11.4;

           11.1.5  Signaling Links and Call-Related Databases, as set forth in
                   subsection 5.4 and Section 17;

           11.1.6  Operations Support Systems, as set forth in subsection 11.5;

           11.1.7  Operator Services and Directory Assistance, as set forth in
                   Section 19; and

           11.1.8  such other Network Elements in accordance with subsection
                   11.7 below.

     11.2  UNBUNDLED LOCAL LOOP ("ULL") TYPES

     Subject to subsection 11.7, BA shall allow NCI to access the following
Unbundled Local Loop ("ULL") types unbundled from local switching and local
transport in accordance with the terms and conditions set forth in this
subsection 11.2.

           11.2.1  "2-Wire Analog Voice Grade ULL" or "Analog 2W" which support
analog transmission of 300-3000 Hz, repeat link start, link reverse battery, or
ground start seizure and disconnect in one direction (toward the End Office
Switch), and repeat ringing in the other direction (toward the Customer). Analog
2W include Loops sufficient for the provision of PBX trunks, pay telephone lines
and electronic key system lines.

           11.2.2  "4-Wire Analog Voice Grade ULL" or "Analog 4W" which support
transmission of voice grade signals using separate transmit and receive paths
and terminate in a 4-wire electrical interface.

           11.2.3  "2-Wire ISDN Digital Grade ULL" or "BRI ISDN" (Premium Link)
which support digital transmission of two 64 Kbps bearer channels and one 16
Kbps data channel. BRI ISDN is a 2B+D Basic Rate Interface-Integrated Services
Digital Network (BRI-ISDN) Loop

                                                                              36
<PAGE>
 
which will meet national ISDN standards and conform to ANSI T1.601-1992 & TlEl.4
90004R3.

          11.2.4 2-Wire ADSL-Compatible ULL or ADSL 2W is a 2-wire, non-loaded,
twisted copper pair that meets revised resistance design or carrier serving area
design guidelines. The upstream and downstream ADSL power spectral density masks
and dc line power limits in BA TR 72575, Issue 2 must be met. ADSL-compatible
local loops are subject to availability.

          11.2.5  2-Wire HDSL-Compatible ULL or HDSL 2W consists of a single
2-wire, non-loaded, twisted copper pair that meets the carrier serving area
design criteria. The HDSL power spectral density mask and dc line power limits
referenced in BA TR 72575, Issue 2 must be met. 2-Wire HDSL-compatible local
loops are subject to availability.

          11.2.6  4-Wire HDSL-Compatible ULL or HDSL 4W consists of two 2-wire,
nonloaded, twisted copper pairs that meet the carrier serving area design
criteria. The HDSL power spectral density mask and dc line power limits
referenced in BA TR 72575, Issue 2 must be met. 4-Wire HDSL-compatible local
loops are subject to availability.

          11.2.7  "4-Wire DS-1-compatible ULL" (Digital Grade Loop) provides a
channel which provides 1.544 Mbps digital transmission path between a Customer
premises and a NCI Collocation node at a BA central office, and is capable of
operating in a full duplex, time division (digital) multiplexing mode. A DS-1
Digital Grade Loop provides transmission capacity equivalent to 24 voice grade
channels with associated signaling, twenty-four 56 Kbps digital channels when in
band signaling is provided or twenty-four 64 Kbps channels with the selection of
the Clear Channel signaling option.

          11.2.8  BA will make Analog 2-Wire ULLs, BRI ISDN ULLs, Analog 4-Wire
ULLs and 4-Wire DS-1-compatible ULLs available for purchase by NCI at any time
after the Effective Date.

          11.2.9  BA will make HDSL 4-Wire, HDSL 2-Wire, and ADSL 2-Wire ULLs
available to NCI no later than the date on which it makes such ULLs commercially
available to any other Telecommunications Carrier in Massachusetts. The Parties
shall amend Exhibit A to add the appropriate rates and charges.

     11.3 UNBUNDLED SWITCHING ELEMENTS

     BA shall make available to NCI the local Switching Element and tandem
Switching Element unbundled from transport, local loop transmission, or other
services in accordance with all Applicable Laws and tariffs and at the rates and
charges specified in Exhibit A, as amended from time to time.

                                                                              37
<PAGE>
 
     11.4  UNBUNDLED INTER OFFICE FACILITIES

           BA shall provide NCI access to an interoffice transmission path of a
fixed capacity between designated central offices that is unbundled from
switching, unbundled multiplexers, and any other network elements in accordance
with Applicable Laws and tariffs and at the rates and charges specified in
Exhibit A, as amended from time to time.

     11.5  OPERATIONS SUPPORT SYSTEMS

           BA shall provide NCI with access via electronic interfaces to
databases required for pre-ordering, ordering, provisioning, maintenance and
repair, and billing as soon as practicable.

     11.6  LIMITATIONS ON UNBUNDLED ACCESS

               11.6.1  BA shall only be required to provide ULLs and Ports where
such Loops and Ports are available.

               11.6.2  NCI shall access BA's unbundled Network Elements
specifically identified in this Agreement via Collocation in accordance with
Section 13 at the BA Wire Center where those elements exist, and each ULL or
Port shall, in the case of Collocation, be delivered to NCI's Collocation node
by means of a Cross Connection. or Strapping. Notwithstanding the foregoing, NCI
may access Signaling Links and Call-Related Databases, Operations Support
Systems, and Operator Services and Directory Assistance by means of tariffed
telecommunications services purchased from BA or a third carrier.

               11.6.3  BA shall provide NCI access to its Unbundled Local Loops
at each of BA's Wire Centers for loops terminating in that Wire Center. In
addition, if NCI orders one or more ULL provisioned via Integrated Digital Link
Carrier or Remote Switching technology deployed as a ULL concentrator, BA shall,
where available, move the requested ULL(s) to a spare, existing physical ULL at
no additional charge to NCI. If, however, no spare physical ULL is available, BA
shall within three (3) business days of NCI's request notify NCI of the lack of
available facilities. NCI may then at its discretion make a Network Element Bona
Fide Request to BA to provide the unbundled Local Loop through the
demultiplexing of the integrated digitized ULL(s). NCI may also make a Network
Element Bona Fide Request for access to Unbundled Local Loops at the ULL
concentration site point. Notwithstanding anything to the contrary in this
Agreement, standard provisioning intervals shall not apply to ULL provided under
this subsection 11. 6.3.

               11.6.4  If NCI orders a ULL type and the distance requested on
such ULL exceeds the transmission characteristics in applicable technical
references, as specified below, distance extensions may be required and
additional rates and charges shall apply as set forth in Exhibit A or applicable
Tariffs.

                                                                              38
<PAGE>
 
     Loop Type                          Technical Reference/Limitation  
     Electronic Key Line                2.5 miles                       
     ISDN                               Bellcore TA-NWT-000393          
     HDSL 2W                            T1E1 Technical Report Number 28 
     HDSL 4W                            T1E1 Technical Report Number 28 
     ADSL 2W                            ANSI T1.413 1995 Specification   

     11.7  AVAILABILITY OF OTHER NETWORK ELEMENTS ON AN UNBUNDLED BASIS

           11.7.1  BA shall, upon request of NCI, and to the extent required by
Applicable Law, provide to NCI access to its Network Elements on an unbundled
basis for the provision of NCI's Telecommunications Service. Any request by NCI
for access to a BA Network Element that is not already available shall be
treated as a Network Element Bona Fide Request. NCI shall provide BA access to
its Network Elements as mutually agreed by the Parties or as required by
Applicable Laws.

           11.7.2  A Network Element obtained by one Party from the other Party
under this subsection 11.7 may be used in combination with the facilities of the
requesting Party only to provide a Telecommunications Service, including
obtaining billing and collection, transmission, and routing of the
Telecommunications Service.

           11.7.3  Notwithstanding anything to the contrary in this subsection
11.7, a Party shall not be required to provide a proprietary Network Element to
the other Party under this subsection 11.7 except as required by the Commission
or FCC.

     11.8  PROVISIONING OF UNBUNDLED LOCAL LOOPS

     The following coordination procedures shall apply for conversions of "live"
Telephone Exchange Services to Unbundled Local Loops (also referred to as "hot
cuts"). These and other mutually agreed-upon procedures shall apply reciprocally
for the "live" cutover of Customers from BA to NCI and from NCI to BA.

           11.8.1  NCI shall request ULLs from BA by delivering to BA a valid
electronic transmittal Service Order using the BA electronic ordering platform
or another mutually agreed upon system. Within two (2) business days of BA's
receipt of such valid Service Order, BA shall provide NCI the firm order
commitment ("FOC") date by which the Loop(s) covered by such Service Order will
be installed.

           11.8.2  BA agrees to accept from NCI at the time the service request
is submitted for scheduled conversion of hot cut ULL orders, a desired date and
A.M. or P.M. designation (the "Scheduled Conversion Time") to the extent
available (as applicable, the "Conversion Window") for the hot cut.

                                                                              39
<PAGE>
 
           11.8.3  BA shall test for NCI dial tone at the POT bay by testing
through the tie cable provisioned between the BA main distributing frame and the
NCI expanded Interconnection node forty-eight (48) hours prior to the Scheduled
Conversion Time.

           11.8.4  Not less than one hour prior to the Scheduled Conversion
Time, either Party may contact the other Party and unilaterally designate a new
Scheduled Conversion Time (the "New Conversion Time"). If the New Conversion
Time is within the Conversion Window, no charges shall be assessed on or waived
by either Party. If, however, the New Conversion Time is outside of the
Conversion Window, the Party requesting such New Conversion Time shall be
subject to the following:

           If BA requests the New Conversion Time, the applicable Line
           Connection Charge shall be waived; and

           If NCI requests the New Conversion Time, NCI shall be assessed a Line
           Connection Charge in addition to the Line Connection Charge that will
           be incurred for the New Conversion Time.

           11.8.5  Except as otherwise agreed by the Parties for a specific
conversion such as large cutovers of ten (10) lines or more that have been
negotiated, the Parties agree that the time interval expected from disconnection
of BA's "live" Telephone Exchange Service to the connection of an unbundled
Network Element at the NCI Collocation node will be accomplished within a window
of time of sixty (60) minutes or less. If NCI has ordered INP with the
installation of a Loop, BA will coordinate the implementation of INP with the
Loop conversion during with the above stated intervals at no additional charge.

           11.8.6  If NCI requests or approves a BA technician to perform
services in excess of or not otherwise contemplated by the Line Connection
Service charge BA may charge NCI for any additional and reasonable labor charges
to perform such services.

           11.8.7  If as the result of end user actions, (e.g. Customer not
                                                          ----
ready ["CNR"]), BA cannot complete requested work activity when technician has
been dispatched to the site, NCI will be assessed a non-recurring charge
associated with this visit. This charge will be the sum of the Service Order
Charge and Premises Visit Charge as specified in the BA's tariff D.T.E. - Mass.-
No. 10.

     11.9  MAINTENANCE OF UNBUNDLED NETWORK ELEMENTS

     If (i) NCI reports to BA a Customer trouble, (ii) NCI requests a dispatch,
(iii) BA dispatches a technician, and (iv) such trouble was not caused by BA
facilities or equipment in whole or in part, then NCI shall pay BA a charge set
forth in Exhibit A for time associated with

                                                                              40
<PAGE>
 
said dispatch. In addition, this charge also applies when the Customer contact
as designated by NCI is not available at the appointed time. NCI accepts
responsibility for initial trouble isolation and providing BA with appropriate
dispatch information based on its test results. If as the result of NCI
instructions, BA is erroneously requested to dispatch within a BA Central Office
or to a POT Bay ("dispatch in"), a charge set forth in Exhibit A will be
assessed per occurrence to NCI by BA. If as the result of NCI instructions, BA
is erroneously requested to dispatch outside a BA Central Office or to a POT Bay
("dispatch out"), a charge set forth in Exhibit A will be assessed per
occurrence to NCI by BA. BA agrees to respond to NCI trouble reports on a non-
discriminatory basis consistent with the manner in which it provides service to
its own retail customers or to any other similarly initiated Telecommunications
Carrier.

     11.10  OTHER TERMS AND CONDITIONS INCLUDING RATES AND CHARGES

            11.10.1      ULLs and other Network Elements will be offered on the
terms and conditions, including rates and charges, specified herein and on such
other terms as stated in applicable Tariffs, as amended from time to time, that
are not inconsistent with the terms and conditions set forth herein.

            11.10.2      BA shall charge the non-recurring and monthly recurring
rates for ULLs and other Network Elements set forth in Exhibit A as interim
rates until such time as the Commission adopts permanent rates consistent with
the requirements of the FCC Regulations. Such permanent rates shall be applied
in the manner described in Exhibit A and subsection 20.1.2 below.

12.0 RESALE -- SECTIONS 251(C)(4) AND 251(B)(1)

     12.1   AVAILABILITY OF WHOLESALE RATES FOR RESALE

     BA shall make available to NCI for resale all Telecommunications Services
that BA provides at retail to Customers that are not Telecommunications Carriers
in accordance with Section 251(c)(4) of the Act, pursuant to the rates, terms
and conditions of BA's tariff D.T.E.- Mass. -No. 14, as amended and in effect
from time to time.

     12.2   AVAILABILITY OF RETAIL RATES FOR RESALE

     Each Party shall make available its Telecommunications Services for resale
at the retail rates set forth in its Tariffs to the other Party in accordance
with Section 251(b)(1) of the Act. In addition, BA and NCI shall each allow
the resale by the other of all Telecommunications Services that are offered
primarily or entirely to other Telecommunications Carriers (e.g., Switched 
                                                            -----
and special Exchange Access Services) at the rates already applicable to such
services. BA shall also allow the resale by NCI of such other non-
Telecommunications Services as BA, in its sole discretion, determines to provide
for resale under terms and conditions to be agreed to by

                                                                              41
<PAGE>
 
the Parties.

     12.3 ADDITIONAL TERMS GOVERNING RESALE AND USE OF BA SERVICES

          12.3.1 NCI shall comply with the provisions of this Agreement
(including, but not limited to, all applicable BA Tariffs) regarding resale or
use of BA services. In addition, NCI shall undertake in good faith to ensure
that its Customers comply with the provisions of BA's Tariffs applicable to
their use of BA's Telecommunications Services.

          12.3.2 Without in any way limiting subsection 12.3.1, NCI shall not
resell (a) residential service to business or other nonresidential Customers of
NCI, (b) Lifeline or other means-tested service offerings, or grandfathered
service offerings, to persons not eligible to subscribe to such service
offerings from BA, or (c) any other BA service in violation of any user or user
group restriction that may be contained in the BA Tariff applicable to such
service to the extent such restriction is not prohibited by Applicable Laws. In
addition, NCI shall be subject to the same limitations that BA's own retail
Customers may be subject to with respect to any Telecommunications Service that
BA may, in its discretion and to the extent not prohibited by Applicable Law,
discontinue offering.

          12.3.3 BA shall not be obligated to offer to NCI at a wholesale
discount Telecommunications Services that BA offers at a special promotional
rate if such promotions are for a limited duration of ninety (90) days or less.

          12.3.4 Upon request by BA, NCI shall provide to BA adequate assurance
of payment of charges due to BA in connection with NCI's purchase of BA services
for resale. Assurance of payment of charges may be requested by BA: if NCI (a)
in BA's reasonable judgment, at the Effective Date or at any time thereafter,
is unable to show itself to be creditworthy; (b) in BA's reasonable judgment, at
the Effective Date or at any time thereafter, is not creditworthy; or, (c) fails
to timely pay a bill rendered to NCI by BA. Unless otherwise agreed by the
Parties, the assurance of payment shall be in the form of a cash deposit and
shall be in an amount equal to the charges for BA services that NCI may
reasonably be expected to incur during a period of two (2) months. BA may at any
time use the deposit or other assurance of payment to pay amounts due from NCI.

          12.3.5 NCI shall not be eligible to participate in any BA plan or
program under which BA end user retail Customers may obtain products or
merchandise, or services which are not BA Retail Telecommunications Services, in
return for trying, agreeing to purchase, purchasing, or using BA Retail
Telecommunications Services.

          12.3.6 BA may impose additional restrictions on NCI's resale of BA's
retail Telecommunications Services to the extent permitted by Applicable Laws.

13.0 COLLOCATION - SECTION 251(C)(6)

                                                                              42
<PAGE>
 
     13.1 BA shall offer to NCI Physical Collocation of equipment necessary for
Interconnection (pursuant to Section 4.0) or for access to unbundled Network
Elements (pursuant to Section 11.0), except that BA may offer only Virtual
Collocation if BA demonstrates to the Commission that Physical Collocation is
not practical for technical reasons or because of space limitations, as provided
in Section 251 (c)(6) of the Act. BA shall provide Collocation solely for the
purpose of Interconnection with facilities or services of BA or access to
unbundled Network Elements of BA, except as otherwise mutually agreed to in
writing by the Parties or as required by the FCC or the Commission, subject to
applicable federal and state Tariffs and license agreements.

     13.2 NCI agrees to offer to BA Collocation of equipment for purposes of
Interconnection (pursuant to Section 4) on a non-discriminatory basis and at
comparable rates, terms and conditions as NCI may provide to other third
parties. NCI shall provide such collocation subject to applicable Tariffs.

     13.3 In the course of implementation of a Collocation project, BA shall:

          (a)  identify the Collocation project manager assigned to the project;

          (b)  develop a written comprehensive "critical tasks" timeline        
               detailing the work (and relative sequence thereof) that is to be 
               performed by each Party or jointly by both Parties; and  

          (c)  provide NCI with the relevant engineering requirements. 

     13.4  The Collocating Party shall purchase Cross Connection to services or
facilities as described in applicable Tariffs. 

     13.5 Collocation shall occur under the terms of each Party's applicable and
available Tariffs.

     13.6  DEDICATED TRANSIT SERVICE

           13.6.1 "Dedicated Transit Service" provides for the dedicated
connection between a NCI Collocation arrangement established pursuant to
applicable tariffs and/or license agreements at a BA premises and a Collocation
arrangement of a third Party carrier that maintains a Collocation arrangement at
the same premises. Dedicated Transit Service shall be provided using a
crossconnection (dedicated connection) using suitable BA provided cable or
transmission facilities or any other mutually agreed upon arrangement.

           13.6.2 The carrier that requests the Dedicated Transit Service shall
be the customer of record for both ends of the service in terms of ordering,
provisioning, maintenance,

                                                                              43
<PAGE>
 
and billing. Alternative arrangements may be utilized if agreed upon by all
three parties. Rates and charges for Dedicated Transit Service are stated in
Exhibit A.

SECTION 251(B) PROVISIONS

14.0 NUMBER PORTABILITY -- SECTION 251(B)(2)

     14.1   SCOPE

            14.1.1 The Parties shall provide Number Portability on a reciprocal
basis to each other to the extent technically feasible, and in accordance with
rules and regulations as from time to time prescribed by the FCC and/or the
Commission. The Parties shall provide Number Portability to each other in the
event a Customer of one Party ("Party A") elects to become a Customer of the
other Party ("Party B") and the Customer (i) remains within the same central
office district and within the boundary of the smallest geographical area that
is significant for billing (e.g. exchange zone) as defined by the LEC to whom
                            ---  
the ported Customer's NXX code was originally assigned and (ii) elects to
utilize the original telephone number(s) correspondent to the Exchange
Service(s) it previously received from Party A in conjunction with the Exchange
Service(s) it will now receive from Party B.

            14.1.2 Until Permanent Number Portability is implemented by the
industry pursuant to regulations issued by the FCC and/or the Commission, the
Parties agree to reciprocally provide Interim Number Portability ("INP") to each
other at the prices listed in Exhibit A. Such agreed-upon prices for INP are not
intended to reflect either Party's views on the cost recovery mechanisms being
considered by the FCC in its current proceeding on number portability issues.

            14.1.3 Upon the agreement of the Parties or issuance of applicable
FCC and/or Commission order(s) or regulations mandating the adoption of a
Permanent Number Portability ("PNP") arrangement, BA and NCI will commence
migration from INP to the agreed-upon or mandated PNP arrangement as quickly as
practically possible while minimizing interruption or degradation of service to
their respective Customers. Once Permanent Number Portability is implemented,
either Party may withdraw, at any time and at its sole discretion, its INP
offerings, subject to advance notice to the other Party and coordination to
allow the seamless and transparent conversion of INP Customer numbers to
Permanent Number Portability. Upon implementation of Permanent Number
Portability pursuant to FCC or Commission regulation, both Parties agree to
conform and provide such Permanent Number Portability. To the extent PNP rates
or cost recovery mechanisms are not established by the applicable FCC or
Commission order or regulation mandating the adoption of PNP, the Parties will
negotiate in good faith the charges or cost recovery mechanism for PNP service
at such time as a PNP arrangement is adopted by the Parties.

            14.1.4 Under either an INP or PNP arrangement, NCI and BA will
implement a process

                                                                              44
<PAGE>
 
to coordinate Number Portability cutovers with ULL conversions (as described in
Section 11 of this Agreement).

     14.2 PROCEDURES FOR PROVIDING INP THROUGH REMOTE CALL FORWARDING

     NCI and BA will provide INP through Remote Call Forwarding as follows:

          14.2.1 A Customer of one Party ("Party A") elects to become a Customer
of the other Party ("Party B"). The Customer elects to utilize the original
telephone number(s) corresponding to the Telephone Exchange Service(s) it
previously received from Party A, in conjunction with the Telephone Exchange
Service(s) it will now receive from Party B. Upon receipt of confirmation of a
signed letter of agency ("LOA") from the Customer (and an associated service
order) assigning the number to Party B, Party A will implement an arrangement
whereby all calls to the original telephone number(s) will be forwarded to a new
telephone number(s) designated by Party B, only within the same Exchange Area as
the original telephone number(s). It is Party B's responsibility to maintain a
file of all LOAs and Party A may request, upon reasonable notice, a copy of the
LOA. Party A will route the forwarded traffic to Party B over the appropriate
Telephone Exchange Service Trunks as if the call had originated on Party A's
network.

          14.2.2 Party B will become the customer of record for the original
Party A telephone numbers subject to the INP arrangements. Party A shall use its
reasonable efforts to consolidate into as few billing statements as possible all
collect, calling card, and 3rd-number billed calls associated with those
numbers, with sub-account detail by retained number. Such billing statement
shall be delivered to Party B in a mutually agreed-upon format via either
electronic file transfer, magnetic tape, or other mutually acceptable medium.

          14.2.3 Party A will update its Line Information Database ("LIDB")
listings for retained numbers, with the screening options provided by Party B on
a per order basis. Party B shall determine which of the screening options
offered by Party A should apply to the Party B Customer account. Party A will
cancel calling cards associated with those forwarded numbers assigned to Party
B.

          14.2.4 Party B will outpulse the telephone number to which the call
has been forwarded to the 911 Tandem Office. Party B will also provide the 911
database with both the forwarded number and the directory number, as well as the
appropriate address information of the Customer.

          14.2.5 Within two (2) business days of receiving notification from the
Customer, Party B shall notify Party A of the Customer's termination of service
with Party B, and shall further notify Party A as to that Customer's
instructions regarding its telephone number(s). Party A will reinstate service
to that Customer, cancel the INP arrangements for that Customer's telephone
number(s), or redirect the INP arrangement to another INP-participating LEC
pursuant

                                                                              45
<PAGE>
 
to the Customer's instructions at the time.

            14.2.6 Party A shall be permitted to cancel INP arrangements and
reassign the telephone number(s) upon receipt of notification from Party B or a
third party that is authorized to act on behalf of the Customer. The Parties
agree to work cooperatively to develop procedures or adopt industry standards or
practices concerning the initiation and termination of INP service in a multi-
carrier environment.

     14.3   PROCEDURES FOR PROVIDING INP THROUGH ROUTE INDEXING

     Upon mutual agreement, BA will deploy a Route Index arrangement which
combines direct trunks, provisioned between BA's and NCI's end offices, with
trunk side routing translations and full functionality for those CLASS services
deployed in the specific BA switch. Under this arrangement, inbound calls to a
ported number will be pointed at a route index that sends the call to a
dedicated trunk group, built as a direct final, for the sole purpose of
facilitating completion of calls to a ported number. BA will coordinate with NCI
to provide this solution in a mutually agreeable and administratively manageable
manner (e.g. NXX level) so as to minimize switch resource utilization for both
        ---  
Parties.

     14.4   PROCEDURES FOR PROVIDING INP THROUGH FULL NXX CODE MIGRATION

     Where either Party has activated an entire NXX for a single Customer, or
activated at least eighty percent (80%) of an NXX for a single Customer, with
the remaining numbers in that NXX either reserved for future use by that
Customer or otherwise unused, if such Customer chooses to receive Telephone
Exchange Service from the other Party, the first Party shall cooperate with the
second Party to have the entire NXX reassigned in the LERG (and associated
industry databases, routing tables, etc.) to an End Office operated by the
second Party. Such transfer will be accomplished with appropriate coordination
between the Parties and subject to appropriate industry lead-times for movements
of NXXs from one switch to another. Neither Party shall charge the other in
connection with this coordinated transfer.

     14.5   OTHER INTERIM NUMBER PORTABILITY OPTIONS

     NCI may also request Direct Inward Dial Trunks pursuant to applicable
tariffs.

     14.6   RECEIPT OF TERMINATING COMPENSATION ON TRAFFIC TO INP'ED NUMBERS

     The Parties agree in principle that, under the INP arrangements described
in subsections 14.2 and 14.3 above, terminating compensation on calls to INP'ed
numbers should be received by each Customer's chosen LEC as if each call to the
Customer had been originally addressed by the caller to a telephone number
bearing an NPA-NXX directly assigned to the Customer's chosen LEC. In order to
accomplish this objective where INP is employed, the Parties shall utilize the
process set forth in this subsection 14.6 whereby terminating compensation on
calls

                                                                              46
<PAGE>
 
subject to INP will be passed from the Party (the "Performing Party") which
performs the INP to the other Party (the "Receiving Party") for whose Customer
the INP is provided.

     14.6.1 The Parties shall individually and collectively make best efforts to
track and quantify INP traffic between their networks based on the CPN of each
call by identifying CPNs which are INP'ed numbers. The Receiving Party shall
charge the Performing Party for each minute of INP traffic at the INP Traffic
Rate specified in subsection 14.6.3 in lieu of any other compensation charges
for terminating such traffic, except as provided in subsection 14.6.2.

     14.6.2 By the Interconnection Activation Date in each LATA, the Parties
shall jointly estimate for the prospective six months, based on historic data of
all traffic in the LATA, the percentages of such traffic that, if dialed to
telephone numbers bearing NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("Recip Traffic"), (ii) appropriate intrastate FGD charges ("Intra
Traffic"), (iii) interstate FGD charges ("Inter Traffic"), or (iv) handling as
Transit Traffic. On the date which is six (6) months after the Interconnection
Activation Date, and thereafter on each succeeding six month anniversary of such
Interconnection Activation Date, the Parties shall establish new INP traffic
percentages to be applied in the prospective six (6) month period, based on the
Performing Party's choice of actual INP traffic percentages from the preceding
six (6) month period or historic data of all traffic in the LATA.

     14.6.3 The INP Traffic Rate shall be equal to the sum of:

(Recip Traffic percentage times the Reciprocal Compensation Rate set forth in
                          -----
Exhibit A)

                                     plus
                                     ----

(Intra Traffic percentage times Receiving Party's effective intrastate FGD
                          -----
rates)

                                     plus
                                     ----

(Inter Traffic percentage times Receiving Party's effective interstate FGD
                          -----
rates).


     14.7 RECOVERY OF INP COSTS PURSUANT TO FCC ORDER AND RULEMAKING

     Notwithstanding anything to the contrary contained in this Section 14, in
light of the FCC's First Report and Order and Further Notice of Proposed
Rulemaking, adopted June 27, 1996, in CC Docket 95-116 (the "Order"), the
Parties stipulate and agree as follows:

          14.7.1 The rates listed in Exhibit A for the provision of INP are
appropriate amounts that each Party providing INP service should recover for the
provision of those INP functionalties in BA's operating territory on an
interim basis until the Commission mandates an alternative cost recovery
mechanism for the provision of INP. For the INP functions it provides, each
Party should be allowed to recover these amounts in a manner consistent with any
final FCC and/or Commission order on INP cost recovery (such as a state-wide
fund contributed to by all telecommunications carriers).

                                                                              47
<PAGE>
 
          14.7.2 The Parties agree that neither Party waives its rights to
advocate its views that are consistent with this subsection 14.7 on the
appropriate INP cost recovery mechanism, or to present such views before any
relevant regulatory body or other agency as they relate to FCC or Commission
actions on INP cost recovery.

15.0 DIALING PARITY - SECTION 251(B)(3)

BA and NCI shall each provide the other with nondiscriminatory access to such
services and information as are necessary to allow the other Party to implement
Dialing Parity for Telephone Exchange Service, operator services, directory
assistance, and directory listing information with no unreasonable dialing
delays, as required under Section 251(b)(3) of the Act.

16.0 ACCESS TO RIGHTS-OF-WAY - SECTION 251(B)(4)

     Each Party ("Licensor") shall provide the other Party ("Licensee") access
for purposes of making attachments to the poles, ducts, rights-of-way and
conduits it owns or controls, pursuant to any existing or future license
agreement between the Parties, and in conformance with 47 U.S.C. 224, where
facilities are available, on terms, conditions and prices comparable to those
offered to any other entity pursuant to each Party's applicable Tariffs
(including generally available license agreements). Where no such Tariffs exist,
such access shall be provided in accordance with the requirements of 47 U.S.C.
224, including any applicable FCC regulations that may be issued.

17.0 DATABASES AND SIGNALING

     17.1 Each Party shall provide the other Party with access to databases and
associated signaling necessary for call routing and completion by providing SS7
Common Channel Signaling (CCS) Interconnection in accordance with existing
Tariffs, Access to 800/888 databases, LIDB, and any other necessary databases
shall be in accordance with existing Tariffs and/or agreements with other
unaffiliated carriers, at the rates set forth in Exhibit A. Alternatively,
either Party may secure CCS Interconnection from a commercial SS7 hub provider,
and in that case the other Party will permit the purchasing Party to access the
same databases as would have been accessible if the purchasing party had
connected directly to the other Party's CCS network. In either case, NCI shall
comply with BA's SS7 certification process prior to establishing CCS
interconnection with BA.

     17.2 The Parties will provide CCS Signaling to each other, where and as
available, in conjunction with all Local Traffic, Toll Traffic, Meet Point
Billing Traffic, and Tandem Transit Traffic. The Parties will cooperate on the
exchange of TCAP messages to facilitate interoperability of CCS-based features
between their respective networks, including all CLASS

                                                                              48
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

features and functions, to the extent each Party offers such features and
functions to its Customers. All CCS Signaling parameters will be provided upon
request (where available), including called party number, calling party number,
originating line information, calling party category, and charge number. All
privacy indicators will be honored. The Parties will follow all Ordering and
Billing Forum-adopted standards pertaining to CIC/OZZ codes. Where CCS Signaling
is not available, in-band multi-frequency (MF) wink start signaling will be
provided. Any such MF arrangement will require a separate local trunk circuit
between the Parties' respective switches in those instances where the Parties
have established End Office to End Office high usage trunk groups. In such an
arrangement, each Party will outpulse the full ten-digit telephone number of the
called party to the other Party.

     17.3 Each Party shall provide trunk groups, where available and upon
reasonable request, that are configured utilizing the B8ZS ESF protocol for 64
kbps clear channel transmission to allow for ISDN interoperability between the
Parties' respective networks.

     17.4 The following publications describe the practices, procedures and
specifications generally utilized by BA for signaling purposes and is listed
herein to assist the Parties in meeting their respective Interconnection
responsibilities related to Signaling:

          (a) Bellcore Generic Requirements, GR-905-CORE, Issue 1, March, 1995,
and subsequent issues and amendments; and

          (b) Bell Atlantic Supplement Common Channel Signaling Network
Interface Specification (BA-905).

          (c) Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC
Networks-Signalling (for MF type signalling).

     17.5 Each Party shall charge the other Party mutual and reciprocal rates
for any usage-based charges for Local and IntraLATA CCS Signaling, 800/888
database access, LIDB access, and access to other necessary databases, as
follows: BA shall charge NCI in accordance with Exhibit A hereto and applicable
Tariffs; NCI shall charge BA rates equal to the rates BA charges NCI, unless
NCI's Tariffs for CCS signaling provide for lower generally available rates, in
which case NCI shall charge BA such lower rates; except to the extent a Party
uses a third party vendor for the provision of CCS Signaling, in which case
mutual and reciprocal rates will not apply. Rates and charges applicable to
third party interconnection can be found in BA's applicable Switched Access
tariffs.

18.0 COORDINATED SERVICE ARRANGEMENTS

     18.1 INTERCEPT AND REFERRAL ANNOUNCEMENTS

     When a Customer changes its service provider from BA to NCI, or from NCI to
     BA, and

                                                                              49
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

does not retain its original telephone number, the Party formerly providing
service to such Customer shall provide a referral announcement ("Referral
Announcement") on the abandoned telephone number which provides details on the
Customer's new number or provide other appropriate information to the extent
known. Referral Announcements shall be provided reciprocally, free of charge to
either the other Party or the Customer, for a period of not less than one
hundred and eighty days (180) days after the date the Customer changes its
telephone number in the case of business Customers and not less than ninety (90)
days after the date the Customer changes its telephone number in the case of
residential Customers or other time periods as may be required by the
Commission. The periods for referral announcement may be shorter if a number
shortage conditions is in effect for a particular NXX code. However, if either
Party provides Referral Announcements for a period different than the above
respective periods when its Customers change their telephone numbers, such Party
shall provide the same level of service to Customers of the other Party.

     18.2 COORDINATED REPAIR CALLS

     NCI and BA will employ the following procedures for handling misdirected
repair calls:

          18.2.1 NCI and BA will educate their respective Customers as to the
correct telephone numbers to call in order to access their respective repair
bureaus.

          18.2.2 To the extent Party A is identifiable as the correct provider
of service to Customers that make misdirected repair calls to Party B, Party B
will immediately refer the Customers to the telephone number provided by Party
A, or to an information source that can provide the telephone number of Party A,
in a courteous manner and at no charge.

          18.2.3 NCI and BA will provide their respective repair contact numbers
to one another on a reciprocal basis.

     18.3 CUSTOMER AUTHORIZATION

          18.3.1 Without in any way limiting either Party's obligations under
subsection 28.1, each Party shall comply with Applicable Laws with regard to
Customer selection of a primary Telephone Exchange Service provider. Until the
Commission and/or FCC adopts regulations and/or orders applicable to Customer
selection of a primary Telephone Exchange Service provider, each Party shall
adhere to the rules and procedures set forth in Section 64.1100 of the FCC
Rules, 47 CFR (S) 64.1100, in effect on the Effective Date hereof when ordering,
terminating, or otherwise changing Telephone Exchange Service on behalf of the
other Party's or another carrier's Customers.

          18.3.2 In the event either Party requests that the other Party
install, provide, change, or terminate a Customer's Telecommunications Service
(including, but not limited to, a Customer's selection of a primary Telephone
Exchange Service Provider) and (a) fails to provide

                                                                              50
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

documentary evidence of the Customer's primary Telephone Exchange Service
Provider selection upon request, or (b) without having obtained authorization
from the Customer for such installation, provision, selection, change or
termination in accordance with Applicable Laws (or as provided in subsection
18.3.1 above), the requesting Party shall be liable to the other Party for all
charges that would be applicable to the Customer for the initial change in the
Customer's Telecommunications Service and any charges for restoring the
Customer's Telecommunications Service to its Customer-authorized condition,
including to the appropriate primary Telephone Exchange Service provider.

          18.3.3 Without in any way limiting NCI's obligations under subsection
28. 1, NCI shall comply with Applicable Laws with regard to Customer Proprietary
Network Information, including, but not limited to, 47 U.S.C. (S) 222. NCI shall
not access (including, but not limited to, through BA OSS Services and BA Pre-
OSS Services), use, or disclose Customer Proprietary Network Information made
available to NCI by BA pursuant to this Agreement unless NCI has obtained any
Customer authorization for such access, use and/or disclosure required by
Applicable Laws. By accessing, using or disclosing Customer Proprietary Network
Information, NCI represents and warrants that it has obtained authorization for
such action from the applicable Customer in the manner required by Applicable
Laws and this Agreement. NCI shall, upon request by BA, provide proof of such
authorization (including a copy of any written authorization).

          18.3.4 BA shall have the right to monitor and/or audit NCI's access to
and use and/or disclosure of Customer Proprietary Network Information that is
made available by BA to NCI pursuant to this Agreement to ascertain whether NCI
is complying with the requirements of Applicable Laws and this Agreement with
regard to such access, use, and/or disclosure. To the extent permitted by
Applicable Laws, the foregoing right shall include, but not be limited to, the
right to electronically monitor NCI's access to and use of Customer Proprietary
Network Information that is made available by BA to NCI pursuant to this
Agreement.

19.0 DIRECTORY AND OPERATOR SERVICES

     19.1 DIRECTORY LISTINGS AND DIRECTORY DISTRIBUTIONS

          19.1.1 BA will include the Customer's primary listing in the
appropriate "White Pages" directories (residence and business listings) and
"Yellow Pages" directories (business listings), as well as in any electronic
directories in which BA's own customers are ordinarily included, and directory
assistance databases, and will distribute such directories to such customers, in
an identical manner in which it provides those functions for its own customers'.
Listings of NCI's Customers will be interfiled with listings of BA's Customers
and the Customers of other LECs included in the BA directories. Where required,
NCI will pay BA a non-recurring charge as set forth in Exhibit A for providing
such service for each NCI Customer's primary listing. NCI will also pay BA's
Tariffed charges, as the case may be, for additional and foreign white page
listings and other white pages services for NCI's Customers. BA will not require
a minimum number of

                                                                              51
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

listings per order.

          19.1.2 Upon request by NCI, BA will make available to NCI a directory
list of relevant NXX codes, the close dates, publishing data, yellow page
headings and call guide close dates on the same basis as such information is
provided to BA's own business offices.

          19.1.3 NCI shall provide BA with daily listing information on all new
NCI Customers in the format required by BA or a mutually-agreed upon industry
standard format, at no charge. The information shall include the Customer's
name, address, telephone number, the delivery address and number of directories
to be delivered, and, in the case of a business listing, the primary business
heading under which the business Customer desires to be placed, and any other
information necessary for the publication and delivery of directories. NCI will
also provide BA with daily listing information showing Customers that have
disconnected or terminated their service with NCI. BA will provide NCI with
confirmation of listing order activity, either through a verification report or
a query on any listing which was not acceptable, within forty-eight (48) hours.

          19.1.4 BA will accord NCI's directory listing information the same
level of confidentiality which BA accords its own directory listing information,
and BA shall ensure that access to NCI's directory listing information will be
used solely for the purpose of providing directory services; provided, however,
that should it determine to do so, BA may use or license information contained
in its directory listings for direct marketing purposes so long as the NCI
Customers are not separately identified as such; and provided further that NCI
may identify those of its Customers that request that their names not be sold
for direct marketing purposes, and BA will honor such requests to the same
extent as it does for its own Customers.

          19.1.5 Both Parties shall use their best efforts to ensure the
accurate listing of NCI Customer listings. BA will provide NCI with a report of
all NCI customer listings no less than ninety (90) days prior to publishing date
for that directory. BA will process any corrections made by NCI with respect to
its listings, provided such corrections are received prior to the close date of
the particular directory. BA will provide appropriate advance notice of
applicable close dates.

          19.1.6 NCI will adhere to all practices, standards, and ethical
requirements of BA with regard to listings, and, by providing BA with listing
information, warrants to BA that NCI has the right to place such listings on
behalf of its Customers. BA will provide NCI, upon request, a copy of the BA
listings standards and specifications manual. NCI agrees that it will undertake
commercially practicable and reasonable steps to attempt to ensure that any
business or person to be listed is authorized and has the right (i) to provide
the product or service offered, and (ii) to use any personal or corporate name,
trade name or language used in the listing. In addition, NCI agrees to release,
defend, hold harmless and indemnify BA from and against any and all claims,
losses, damages, suits, or other actions, or any liability whatsoever, suffered,
made, instituted, or asserted by any person arising out of BA's listing of the
listing information provided by NCI hereunder.

                                                                              52
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

          19.1.7 BA's liability to NCI in the event of a BA error in or omission
of a listing shall not exceed the amount of charges actually paid by NCI for
such listing. In addition, NCI agrees to take, with respect to its own
Customers, all reasonable steps to ensure that its and BA's liability to NCI's
Customers in the event of a BA error in or omission of a listing shall be
subject to the same limitations that BA's liability to its own Customers are
subject to.

     19.2 SERVICE INFORMATION PAGES

     BA will include all NCI NXX codes associated with the areas to which each
directory pertains, to the extent it does so for BA's own NXX codes, in any
lists of such codes which are contained in the general reference portions of the
directories. NCI's NXX codes shall appear in such lists in the same manner as
BA's NXX information. In addition, when NCI is authorized to, and is offering,
local service to end-users located within the geographic region covered by a
specific directory, at NCI request, BA will include in the "Customer Guide" or
comparable section of the applicable white pages directories listings provided
by NCI for NCI's installation, repair and customer service and other essential
local service oriented information, as agreed by the Parties, including
appropriate identifying logo. Such listings shall appear in the manner agreed to
by the Parties. NCI will be responsible for providing the necessary information
to BA by the applicable close date for the particular directory. BA will provide
NCI with the close dates and reasonable notice of any changes in said dates. BA
shall not charge NCI for inclusion of this essential local service-oriented
information, but reserves the right to impose charges on other information NCI
may elect to submit and BA may elect to accept for inclusion in BA's white pages
directories.

     19.3 YELLOW PAGES MAINTENANCE

     The Parties agree to work cooperatively to ensure that Yellow Page
advertisements purchased by Customers that switch their service to NCI
(including Customers utilizing NCI-assigned telephone numbers and NCI Customers
utilizing LTNP) are maintained without interruption. BA will offer Yellow Pages
services to NCI Customers on the same basis as they are offered to BA Customers.

     19.4 DIRECTORY ASSISTANCE (DA) AND OPERATOR SERVICES (OS)

          19.4.1 Upon request, BA will provide NCI with directory assistance
and/or IntraLATA operator services substantially in accordance with the rates
and terms set forth in the Directory Assistance and Operator Services Agreement
appended hereto as Exhibit C.

          19.4.2 NCI shall arrange at its expense the trunking and other
facilities required to transport to and from the designated DA and OS switch
locations.

19.5 WHOLESALE BUSY LINE VERIFICATION AND INTERRUPT (BLV/I)

          19.5.1 Wholesale Busy Line Verification permits the operator of one
local carrier

                                                                              53
<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

to request the status of access lines (conversation in progress, available to
receive calls, or out of order) that are served by another local carrier.
Interrupt allows the operator of one local carrier to request interruption of
conversation on access lines that have been determined to be in use.

          19.5.2 If Local Carrier A decides or is required by a regulatory body
of competent jurisdiction to offer BLV/I services to enable its Customers to
verify and/or interrupt calls of Local Carrier B's Customers, the operator
bureau of Local Carrier B shall accept and respond to Wholesale BLV/I requests
from the operator bureau of Local Carrier A. NCI and Bell Atlantic shall
compensate the other Local Carrier for Wholesale BLV/I inquiries in accordance
with the rates of the other Local Carrier's Tariff or at the rates specified in
Exhibit A of this Agreement for Wholesale BLV/I.

          19.5.3 The Local Carrier B operator shall only verify the status of
the line or interrupt the line to inform the called party that another caller is
attempting to reach them. The Local Carrier B operator will not complete the
telephone call of the Customer initiating the BLV/I request. The Local Carrier B
operator will make only one Wholesale BLV/I attempt per operator bureau
telephone request, and the applicable charges apply whether or not the called
party releases the line. Wholesale BLV/I cannot be performed on telephone
numbers utilizing a "call forwarding" feature. The operator shall respond to
only one telephone number per call on requests for Wholesale BLV/1.

          19.5.4 Each Local Carrier shall route Wholesale BLV/I traffic
inquiries over separate direct trunks groups (and not the
Local/IntraLATA/InterLATA Trunks) established between the Local Carriers'
respective operator bureaus. Each Party shall offer interconnection for
Wholesale BLV/I traffic at its operator services switch serving the LATA or
other mutually agreed point within the LATA. Unless otherwise mutually agreed,
the Parties shall configure Wholesale BLV/I trunks over the Interconnection
architectures in accordance with the terms of Section 4 of this Agreement. Local
Carrier A shall outpulse the appropriate NPA, ATC Code, and Routing Code
(operator code) to Local Carrier B.

20.0 COORDINATION WITH TARIFF TERMS

     20.1 The Parties acknowledge that some of the services, facilities, and
arrangements described herein are or will be available under and subject to the
terms of the federal or state tariffs of the other Party applicable to such
services, facilities, and arrangements. To the extent a Tariff of the providing
Party applies to any service, facility, and arrangement described herein, the
Parties agree as follows:

          20.1.1 Those rates and charges set forth in Exhibit A for the
services, facilities, and arrangements described herein that reference or are
identical to a rate contained in an existing Tariff of the providing Party,
shall conform with those contained in the then-prevailing Tariff and vary in
accordance with any changes that may be made to the Tariff rates and charges
subsequent to the Effective Date.

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                 NCI - BELL ATLANTIC Interconnection Agreement

          20.1.2 As applied to wholesale discount rates, unbundled Network
Elements or termination of Reciprocal Compensation Traffic and other
Interconnection services purchased for the provision of Telephone Exchange
Service or Exchange Access, the rates and charges set forth in Exhibit A shall
apply until such time as they are replaced by new rates as may be approved by
the Commission from time to time, subject to a stay or other order issued by any
court of competent jurisdiction. At such time(s) as such new rates have been
approved by the Commission, the Parties shall amend Exhibit A to reflect the new
approved rates.

     20.2 Except with respect to the rates and charges described in subsection
20.1 above, all other terms contained in an applicable Tariff of the providing
Party shall apply in connection with its provision of the particular service,
facility, and arrangement hereunder.

21.0 INSURANCE

     21.1 At all times during the term of this Agreement each Party shall keep
and maintain in force at each Party's expense all insurance required by law
(e.g., workers' compensation insurance) as well as general liability insurance
for personal injury or death to any one person, property damage resulting from
any one incident, automobile liability with coverage for bodily injury for
property damage. Upon request from the other Party, each Party shall provide to
the other Party evidence of such insurance (which may be provided through a
program of self insurance).

22.0 TERM AND TERMINATION

     22.1 This Agreement shall be effective as of the date first above written
and continue in effect until June 24, 2000, and thereafter the Agreement shall
continue in force and effect unless and until terminated as provided herein.
Upon the expiration of the initial term, either Party may terminate this
Agreement by providing written notice of termination to the other Party, such
written notice to be provided at least ninety (90) days in advance of the date
of termination. In the event of such termination, those service arrangements
made available under this Agreement and existing at the time of termination
shall continue without interruption under (a) a new agreement executed by the
Parties, (b) standard Interconnection terms and conditions approved and made
generally effective by the Commission, (c) Tariff terms and conditions generally
available to CLECs, or (d) if none of the above is available, under the terms of
this Agreement on a month-to-month basis until such time as (a), (b), or (c)
becomes available.

     22.2 For service arrangements made available under this Agreement and
existing at the time of termination, if the standard Interconnection terms and
conditions or Tariff terms and conditions result in the non-terminating Party
physically rearranging facilities or incurring programming expense, the non-
terminating Party shall be entitled to recover such rearrangement or programming
costs from the terminating Party, provided that such non-terminating Party
advised the other Party of such expenses in writing within a reasonable time
after they were

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                 NCI - BELL ATLANTIC Interconnection Agreement

incurred.

     22.3 If either Party defaults in the payment of any amount due hereunder,
or if either Party violates any other provision of this Agreement, and such
default or violation shall continue for sixty (60) days after written notice
thereof, the other Party may terminate this Agreement and services hereunder by
written notice; provided the other Party has provided the defaulting Party and
the appropriate federal and/or state regulatory bodies with written notice at
least twenty-five (25) days prior to terminating service. Notice shall be posted
by overnight mail, return receipt requested. If the defaulting Party cures the
default or violation within the twenty-five (25) day period, the other Party
will not terminate service or this Agreement but shall be entitled to recover
all costs, if any, incurred by it in connection with the default or violation,
including, without limitation, costs incurred to prepare for the termination of
service.

23.0 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NO PARTY MAKES OR
RECEIVES ANY WARRANTY, EXPRESS OR IMPLIED, WITH RESPECT TO THE SERVICES,
FUNCTIONS AND PRODUCTS IT PROVIDES UNDER OR CONTEMPLATED BY THIS AGREEMENT AND
THE PARTIES DISCLAIM THE IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR
A PARTICULAR PURPOSE.

24.0 CANCELLATION CHARGES

     Except as provided in this Agreement or as otherwise provided in any
applicable Tariff, no cancellation charges shall apply.

25.0 INDEMNIFICATION

     25.1 Each Party agrees to release, indemnify, defend and hold harmless the
other Party from and against all losses, claims, demands, damages, expenses,
suits or other actions, or any liability whatsoever, including, but not limited
to, costs and attorneys' fees (collectively, a "Loss"), (a) whether suffered,
made, instituted, or asserted by any other party or person, relating to personal
injury to or death of any person, or for loss, damage to, or destruction of real
and/or personal property, whether or not owned by others, arising from
transactions or activities relating to this Agreement and to the extent
proximately caused by the negligent or willful acts or omissions of the
indemnifying Party, regardless of the form of action, (b) suffered, made,
instituted, or asserted by its own customer(s) against the other Party arising
out of the other Party's provision of services to the indemnifying Party under
this Agreement, (c) claims for libel, slander, infringement of copyright arising
from the material transmitted over the Indemnified Party's facilities arising
from the Indemnifying Party's own communications or the communications of such
Indemnifying Party's Customers, or (d) claims for infringement of patents
arising from combining the Indemnified Party's facilities or services with, or
the using of the Inderrinified Party's services or facilities in connection
with, facilities of the Indemnifying

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                 NCI - BELL ATLANTIC Interconnection Agreement

Party. Notwithstanding the foregoing indemnification, nothing in this Section
25.0 shall affect or limit any claims, remedies, or other actions the
indemnifying Party may have against the indemnified Party under this Agreement,
any other contract, or any applicable Tariff(s), regulations or laws for the
indemnified Party's provision of said services.

     25.2 The indemnification provided herein shall be conditioned upon:

          (a) The indemnified Party shall promptly notify the indemnifying Party
     of any action taken against the indemnified Party relating to the
     indemnification.

          (b) The indemnifying Party shall have sole authority to defend any
     such action, including the selection of legal counsel, and the indemnified
     Party may engage separate legal counsel only at its sole cost and expense.

          (c) In no event shall the indemnifying Party settle or consent to any
     judgment pertaining to any such action without the prior written consent of
     the indemnified Party, which consent shall not be unreasonably delayed or
     withheld. However, in the event the settlement or judgment requires a
     contribution from or affects the rights of the Indemnified Party, the
     Indemnified Party shall have the right to refuse such settlement or
     judgment and, at its own cost and expense, take over the defense against
     such Loss, provided that in such event the indemnifying Party shall not be
     responsible for, nor shall it be obligated to indemnify the indemnified
     Party against, the Loss for any amount in excess of such refused settlement
     or judgment.

          (d) The indemnified Party shall, in all cases, assert any and all
     provisions in its Tariffs that limit liability to third parties as a bar to
     any recovery by the third party claimant in excess of such limitation of
     liability.

          (e) The indemnified Party shall offer the indemnifying Party all
     reasonable cooperation and assistance in the defense of any such action.

     25.3 Notwithstanding this indemnification provision or any other provision
in the Agreement, neither Party, nor its parent, subsidiaries, affiliates,
agents, servants, or employees shall be liable to the other for "Consequential
Damages" as that term is described in Section 26.2 below.

26.0 LIMITATION OF LIABILITY

     26.1 Except as provided in Section 25 and 27, no liability shall attach to
either Party, its parents, subsidiaries, affiliates, agents, servants or
employees for damages arising from errors, mistakes, omissions, interruptions,
or delays in the course of establishing, furnishing, rearranging, moving,
terminating, changing, or providing or failing to provide services or facilities
(including the obtaining or furnishing of information with respect thereof or
with respect to users of the services or facilities) in the absence of gross
negligence or willful

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                 NCI - BELL ATLANTIC Interconnection Agreement

misconduct.

     26.2 Neither Party shall be liable to the other in connection with the
provision or use of services offered under this Agreement for indirect,
incidental, consequential, reliance or special damages, including (without
limitation) damages for lost profits (collectively, "Consequential Damages"),
regardless of the form of action, whether in contract, warranty, strict
liability, or tort, including, without limitation, negligence of any kind, even
if the other Party has been advised of the possibility of such damages.

     26.3 The Parties agree that neither Party shall be liable to the customers
of the other Party in connection with its provision of services to the other
Party under this Agreement. Nothing in this Agreement shall be deemed to create
a third party beneficiary relationship between the Party providing the service
and the customers of the Party purchasing the service. In the event of a dispute
involving both Parties with a customer of one Party, both Parties shall assert
the applicability of any limitations on liability to customers that may be
contained in either Party's applicable Tariff(s).

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<PAGE>
 
                 NCI - BELL ATLANTIC Interconnection Agreement

27.0 PERFORMANCE STANDARDS FOR SPECIFIED ACTIVITIES

     27.1 PERFORMANCE STANDARDS

     BA shall provide the Interconnection and unbundled Network Elements
contemplated hereunder in accordance with the performance standards set forth in
Section 251(c) of the Act and the FCC Regulations.

     27.2 PERFORMANCE REPORTING

          27.2.1 At such time as BA makes available the Performance Monitoring
Reports described by the FCC Order in the Application of BELL ATLANTIC
Corporation, Transferee, For Consent to Transfer Control of BELL ATLANTIC
Corporation and its Subsidiaries, NSD-L-96-10, Memorandum Opinion and Order
(August 14, 1997) ("the FCC Merger Order") to other Telecommunications Carriers
purchasing Interconnection from BA, BA shall provide NCI with the Performance
Monitoring Reports applicable to NCI in accordance with the requirements of said
FCC Merger Order.

          27.2.2 NCI agrees that the performance information included in the
Performance Monitoring Reports is confidential and proprietary to BA, and shall
be used by NCI solely for internal performance assessment purposes, for purposes
of joint NCI and BA assessments of service performance, and for reporting to the
Commission, the FCC, or courts of competent jurisdiction, under cover of an
agreed-upon protective order, for the sole purpose of enforcing BA's obligations
hereunder. NCI shall not otherwise disclose this information to third parties.

     27.3 LIQUIDATED DAMAGES

     At any time during the effectiveness of this Agreement, NCI shall have the
right to select any liquidated damages mechanism adopted by the FCC pursuant to
the FCC Merger Order or by the DTE in the Consolidated Arbitrations and to have
such mechanism incorporated into, and effective with respect to performance
under, this Agreement.

28.0 COMPLIANCE WITH LAWS; REGULATORY APPROVAL

     28.1 Each Party shall promptly notify the other Party in writing of any
governmental action that suspends, cancels, withdraws, limits, or otherwise
materially affects its ability to perform its obligations hereunder.

     28.2 The Parties understand and agree that this Agreement will be filed
with the Commission and may thereafter be filed with the FCC as an integral part
of BA's application pursuant to Section 271 (d) of the Act. The Parties covenant
and agree that this Agreement is satisfactory to them as an agreement under
Section 251 of the Act. Each Party covenants and agrees to fully support
approval of this Agreement by the Commission or the FCC under Section 252 of the
Act without modification. The Parties, however, reserve the right to seek
regulatory

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                 NCI - BELL ATLANTIC Interconnection Agreement

relief and otherwise seek redress from each other regarding performance and
implementation of this Agreement, including, without limitation, the conformance
of this Agreement to the FCC Regulations as provided in subsection 28.3 below.

     28.3 The Parties recognize that the FCC has issued and may continue to
issue regulations implementing Sections 251, 252, and 271 of the Act that affect
certain terms contained in this Agreement. In the event that any one or more of
the provisions contained herein is inconsistent with any applicable rule
contained in such FCC Regulations or, in BA's reasonable determination, affects
BA's application pursuant to Section 271 (d) of the Act, the Parties agree to
make only the minimum revisions necessary to eliminate the inconsistency or
amend the application-affecting provision(s). Such minimum revisions shall not
be considered material, and shall not require further Commission approval
(beyond any Commission approval required under Section 252(e) of the Act).

     28.4 In the event any Applicable Law other than the FCC Regulations
requires modification of any material term(s) contained in this Agreement,
either Party may require a renegotiation of the term(s) that require direct
modification as well as of any term(s) that are reasonably affected thereby. If
neither Party requests a renegotiation or if an Applicable Law requires
modification of any non-material term(s), then the Parties agree to make only
the minimum modifications necessary, and the remaining provisions of this
Agreement shall remain in full force and effect.

     28.5 Compliance with the Communications Assistance for Law Enforcement Act
of 1994 ("CALEA"). Each Party represents and warrants that any equipment,
facilities or services provided to the other Party under this Agreement comply
with CALEA. Each Party shall indemnify and hold the other Party harmless from
any and all penalties imposed upon the other Party for such noncompliance and
shall at the non-compliant Party's sole cost and expense, modify or replace any
equipment, facilities or services provided to the other Party under this
Agreement to ensure that such equipment, facilities and services fully comply
with CALEA.

29.0 MISCELLANEOUS

     29.1 AUTHORIZATION

          29.1.1 BA is a corporation duly organized, validly existing and in
good standing under the laws of the Commonwealth of Massachusetts and has full
power and authority to execute and deliver this Agreement and to perform the
obligations hereunder.

          29.1.2 NCI is a corporation duly organized, validly existing and in
good standing under the laws of the Commonwealth of Massachusetts, and has full
power and authority to execute and deliver this Agreement and to perform its
obligations hereunder.

     29.2 INDEPENDENT CONTRACTOR

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                 NCI - BELL ATLANTIC Interconnection Agreement

     Each Party shall perform services hereunder as an independent contractor
and nothing herein shall be construed as creating any other relationship between
the Parties. Each Party and each Party's contractor shall be solely responsible
for the withholding or payment of all applicable federal, state and local income
taxes, social security taxes and other payroll taxes with respect to their
employees, as well as any taxes, contributions or other obligations imposed by
applicable state unemployment or workers' compensation acts. Each Party has sole
authority and responsibility to hire, fire and otherwise control its employees.

     29.3 FORCE MAJEURE

     Neither Party shall be responsible for delays or failures in performance
resulting from acts or occurrences beyond the reasonable control of such Party,
regardless of whether such delays or failures in performance were foreseen or
foreseeable as of the date of this Agreement, including, without limitation:
adverse weather conditions, fire, explosion, power failure, acts of God, war,
revolution, civil commotion, or acts of public enemies; any law, order,
regulation, ordinance or requirement of any government or legal body; or labor
unrest, including, without limitation, strikes, slowdowns, picketing or
boycotts; or delays caused by the other Party or by other service or equipment
vendors; or any other circumstances beyond the Party's reasonable control. In
such event, the affected Party shall, upon giving prompt notice to the other
Party, be excused from such performance on a day-to-day basis to the extent of
such interferences (and the other Party shall likewise be excused from
performance of its obligations on a day-to-day basis to the extent such Party's
obligations relate to the performance so interfered with). The affected Party
shall use its best efforts to avoid or remove the cause(s) of non-performance
and both Parties shall proceed to perform with dispatch once the cause(s) are
removed or cease.

     29.4 CONFIDENTIALITY

          29.4.1 All information, including but not limited to specification,
microfilm, photocopies, magnetic disks, magnetic tapes, drawings, sketches,
models, samples, tools, technical information, data, employee records, maps,
financial reports, and market data, (i) furnished by one Party to the other
Party dealing with customer specific, facility specific, or usage specific
information, other than customer information communicated for the purpose of
publication or directory database inclusion, or (ii) in written, graphic,
electromagnetic, or other tangible form and marked at the time of delivery as
"Confidential" or "Proprietary," or (iii) communicated orally and declared to
the receiving Party at the time of delivery, and by written notice given to the
receiving Party within ten (10) days after delivery, to be "Confidential" or
"Proprietary" (collectively referred to as "Proprietary Information"), shall
remain the property of the disclosing Party. With respect to the information
described in (i) above, the Party furnishing the information shall use
reasonable efforts to mark such information at the time of delivery as
"Confidential" or "Proprietary."

          29.4.2 Each Party shall keep all of the other Party's Proprietary
Information confidential in the same manner it holds its own Proprietary
Information confidential (which in all cases shall be no less than reasonable)
and shall use the other Party's Proprietary Information only

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<PAGE>
 
for performing the covenants contained in this Agreement. Neither Party shall
use the other Party's Proprietary Information for any other purpose except upon
such terms and conditions as may be agreed upon between the Parties in writing.

          29.4.3  Unless otherwise agreed, the obligations of confidentiality
and non-use set forth in this Agreement do not apply to such Proprietary
Information that:

          (a)     was, at the time of receipt, already known to the receiving
     Party free of any obligation to keep it confidential as evidenced by
     written records prepared prior to delivery by the disclosing Party; or

          (b)     is or becomes publicly known through no wrongful act of the
     receiving Party; or

          (c)     is rightfully received from a third person having no direct or
     indirect secrecy or confidentiality obligation to the disclosing Party with
     respect to such information; or

          (d)     is independently developed by an employee, agent, or
     contractor of the receiving Party that is not involved in any manner with
     the provision of services pursuant to this Agreement and does not have any
     direct or indirect access to the Proprietary Information; or

          (e)     is approved for release by written authorization of the
     disclosing Party; or

          (f)     is required to be made public by the receiving Party pursuant
     to applicable law or regulation, provided that the receiving Party shall
     give sufficient notice of the requirement to the disclosing Party to enable
     the disclosing Party to seek protective orders.

          29.4.4  Upon request by the disclosing Party, the receiving Party
shall return all tangible copies of Proprietary Information, whether written,
graphic, electromagnetic or otherwise, except that the receiving Party may
retain one copy for archival purposes only.

          29.4.5  Notwithstanding any other provision of this Agreement, the
provisions of this subsection 29.4 shall apply to all Proprietary Information
furnished by either Party to the other in furtherance of the purpose of this
Agreement, even if furnished before the Effective Date.

     29.5 CHOICE OF LAW

     The construction, interpretation and performance of this Agreement shall be
governed by and construed in accordance with the laws of the state in which this
Agreement is to be performed, except for its conflicts of laws provisions. In
addition, insofar as and to the extent federal law may apply, federal law will
control.

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<PAGE>
 
     29.6 TAXES

     Each Party purchasing services hereunder shall pay or otherwise be
responsible for all federal, state, or local sales, use, excise, gross receipts,
transaction or similar taxes, fees or surcharges levied against or upon such
purchasing Party (or the providing Party when such providing Party is permitted
to pass along to the purchasing Party such taxes, fees or surcharges), except
for any tax on either Party's corporate existence, status or income. Whenever
possible, these amounts shall be billed as a separate item on the invoice. To
the extent a sale is claimed to be for resale tax exemption, the purchasing
Party shall furnish the providing Party a proper resale tax exemption
certificate as authorized or required by statute or regulation by the
jurisdiction providing said resale tax exemption. Failure to timely provide said
resale tax exemption certificate will result in no exemption being available to
the purchasing Party.

     29.7 ASSIGNMENT

     Either Party may assign this Agreement or any of its rights or obligations
hereunder to a third party, including, without limitation, its parent or other
affiliate, with the other Party's prior written consent, which consent shall not
be unreasonably delayed or withheld upon the provision of reasonable evidence by
the proposed assignee that it has the resources, ability, and authority to
provide satisfactory performance under this Agreement. Any assignment or
delegation in violation of this subsection 29.7 shall be void and ineffective
and constitute a default of this Agreement.

     29.8 BILLING AND PAYMENT; DISPUTED AMOUNTS

          29.8.1 Except as may otherwise be provided in this Agreement, each
Party shall submit on a monthly basis an itemized statement of charges incurred
by the other Party during the preceding month(s) for services rendered
hereunder. Payment of billed amounts under this Agreement, whether billed on a
monthly basis or as otherwise provided herein, shall be due, in immediately
available U.S. funds, within thirty (30) days of the date of such statement.

          29.8.2 Although it is the intent of both Parties to submit timely and
accurate statements of charges, failure by either Party to present statements to
the other Party in a timely manner shall not constitute a breach or default, or
a waiver of the right to payment of the incurred charges, by the billing Party
under this Agreement, and the billed Party shall not be entitled to dispute the
billing Party's statement(s) based on such Party's failure to submit them in a
timely fashion.

          29.8.3 If any portion of an amount due to a Party (the "Billing
Party") under this Agreement is subject to a bona fide dispute between the
Parties, the Party billed (the "Non-Paying Party") shall within thirty (30) days
of its receipt of the invoice containing such disputed amount give notice to the
Billing Party of the amounts it disputes ("Disputed Amounts") and include in
such notice the specific details and reasons for disputing each item. The Non-
Paying Party shall pay when due (i) all undisputed amounts to the Billing Party
and (ii) all

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Disputed Amounts into an interest bearing escrow account with a third Party
escrow agent mutually agreed upon by the Parties.

          29.8.4 If the Parties are unable to resolve the issues related to the
Disputed Amounts in the normal course of business within ninety (90) days after
delivery to the Billing Party of notice of the Disputed Amounts, each of the
Parties shall appoint a designated representative who has authority to settle
the dispute and who is at a higher level of management than the persons with
direct responsibility for administration of this Agreement. The designated
representatives shall meet as often as they reasonably deem necessary in order
to discuss the dispute and negotiate in good faith in an effort to resolve such
dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

          29.8.5 If the Parties are unable to resolve issues related to the
Disputed Amounts within forty-five (45) days after the Parties' appointment of
designated representatives pursuant to subsection 29.9, then either Party may
file a complaint with the Commission to resolve such issues or proceed with any
other remedy pursuant to law or equity. The Commission may direct release of any
or all funds (including any accrued interest) in the escrow account, plus
applicable late fees, to be paid to either Party.

          29.8.6 The Parties agree that all negotiations pursuant to this
subsection 29.8 shall remain confidential and shall be treated as compromise and
settlement negotiations for purposes of the Federal Rules of Evidence and state
rules of evidence.

          29.8.7 Any undisputed amounts not paid when due shall accrue interest
from the date such amounts were due at the lesser of (i) one and one-half
percent (1- 1/2%) per month or (ii) the highest rate of interest that may be
charged under applicable law.

     29.9  DISPUTE RESOLUTION

     Any dispute between the Parties regarding the interpretation or enforcement
of this Agreement or any of its terms shall be addressed by good faith
negotiation between the Parties, in the first instance. Should such negotiations
fail to resolve the dispute in a reasonable time, either Party may initiate an
appropriate action in any regulatory or judicial forum of competent
jurisdiction.

     29.10 NOTICES

     Except as otherwise provided in this Agreement, notices given by one Party
to the other Party under this Agreement shall be in writing and shall be (a)
delivered personally, (b) delivered by express delivery service, (c) mailed,
certified mail or first class U.S. mail postage prepaid, return receipt
requested, or (d) delivered by telescope to the following addresses of the
Parties:

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<PAGE>
 
          To NCI:

          Nathaniel Morse, President  
          Norfolk County Internet, Inc.
          Unit 12A Depot Plaza        
          13-25 Main Street           
          Franklin, MA 02038           

          Facsimile: (508)520-1382

          with a copy to:

          Emmett Lyne, Esq.                   
          Rich, May, Bilodeau & Flaherty, P.C.
          The Old South Building              
          294 Washington Street               
          Boston, MA 02108                     

          Facsimile: (617)556-3889

          To BA:

          BELL ATLANTIC 
          1095 Avenue of Americas 
          40th Floor 
          New York NY 10036 
          Attn: President - Telecommunications Industry Services 
          Facsimile: (212)597-2585 
          with a copy to:

          BELL ATLANTIC
          1095 Avenue of Americas
          40th Floor
          New York, NY 10036
          Attn: General Counsel
          Facsimile: (212)597-2560

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual
receipt, (ii) the next business day when notice is sent via express mail or
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail, or (iv) on the date set forth on the confirmation in the
case of

                                                                              65
<PAGE>
 
telecopy.

     29.11 SECTION 252(I) OBLIGATIONS

           29.11.1 To the extent required under Applicable Law, BA shall make
available to NCI any interconnection, service or network element provided under
an agreement approved by the Commission under Section 252 of the Act to which BA
is a party upon the same terms and conditions as those provided in the
agreement.

     29.12 JOINT WORK PRODUCT

     This Agreement is the joint work product of the Parties and has been
negotiated by the Parties and their respective counsel and shall be fairly
interpreted in accordance with its terms and, in the event of any ambiguities,
no inferences shall be drawn against either Party.

     29.13 NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY

     This Agreement is for the sole benefit of the Parties and their permitted
assigns, and nothing herein express or implied shall create or be construed to
create any third-party beneficiary rights hereunder. Except for provisions
herein expressly authorizing a Party to act for another, nothing in this
Agreement shall constitute a Party as a legal representative or agent of the
other Party, nor shall a Party have the right or authority to assume, create or
incur any liability or any obligation of any kind, express or implied, against
or in the name or on behalf of the other Party unless otherwise expressly
permitted by such other Party. Except as otherwise expressly provided in this
Agreement, no Party undertakes to perform any obligation of the other Party,
whether regulatory or contractual, or to assume any responsibility for the
management of the other Party's business.

     29.14 NO LICENSE

           29.14.1 Except as may be expressly provided herein, nothing in this
Agreement shall be construed as the grant of a license with respect to any
patent, copyright, trademark, trade name, trade secret or any other proprietary
or intellectual property now or hereafter owned, controlled or licensable by
either Party. Neither Party may use any patent, copyrightable materials,
trademark, trade name, trade secret or other intellectual property right of the
other Party except in accordance with the terms of a separate license agreement
between the Parties granting such rights.

           29.14.2 Neither Party shall have any obligation to defend, indemnify
or hold harmless, or acquire any license or right for the benefit of, or owe any
other obligation or have any liability to, the other Party or its customers
based on or arising from any claim, demand, or proceeding by any third party
alleging or asserting that the use of any circuit, apparatus, or system, or the
use of any software, or the performance of any service or method, or the
provision of any

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facilities by either Party under this Agreement, alone or in combination with
that of the other Party, constitutes direct, vicarious or contributory
infringement or inducement to infringe, misuse or misappropriation of any
patent, copyright, trademark, trade secret, or any other proprietary or
intellectual property right of any Party or third party. Each Party, however,
shall offer to the other reasonable cooperation and assistance in the defense of
any such claim.

           29.14.3 NOTWITHSTANDING ANY OTHER PROVISION OF THIS AGREEMENT, THE
PARTIES AGREE THAT NEITHER PARTY HAS MADE, AND THAT THERE DOES NOT EXIST, ANY
WARRANTY, EXPRESS OR IMPLIED, THAT THE USE BY THE PARTIES OF THE OTHER'S
FACILITIES, ARRANGEMENTS, OR SERVICES PROVIDED UNDER THIS AGREEMENT SHALL NOT
GIVE RISE TO A CLAIM BY ANY THIRD PARTY OF INFRINGEMENT, MISUSE, OR
MISAPPROPRIATION OF ANY INTELLECTUAL PROPERTY RIGHT OF SUCH THIRD PARTY.

     29.15 TECHNOLOGY UPGRADES

     Nothing in this Agreement shall limit the ability of either Party to
upgrade its network through the incorporation of new equipment, new software or
otherwise. The Party making the upgrade shall provide written notice to the
other Party at least ninety (90) days prior to the incorporation of any such
upgrades in its network that will materially affect the service of the other
Party, and shall exercise reasonable efforts to provide at least one hundred
eighty (180) days notice where practicable. In addition, each Party shall comply
with the FCC Network Disclosure rules set forth in the FCC Regulations to the
extent applicable. Each Party shall be solely responsible for the cost and
effort of accommodating such changes in its own network.

     29.16 SURVIVAL

     The Parties' obligations under this Agreement which by their nature are
intended to continue beyond the termination or expiration of this Agreement
shall survive the termination or expiration of this Agreement.

     29.17 ENTIRE AGREEMENT

     The terms contained in this Agreement and any Schedules, Exhibits, tariffs
and other documents or instruments referred to herein, which are incorporated
into this Agreement by this reference, constitute the entire agreement between
the Parties with respect to the subject matter hereof, superseding all prior
understandings, proposals and other communications, oral or written. Neither
Party shall be bound by any preprinted terms additional to or different from
those in this Agreement that may appear subsequently in the other Party's form
documents, purchase orders, quotations, acknowledgments, invoices or other
communications.

                                                                              67
<PAGE>
 
     29.18 COUNTERPARTS

     This Agreement may be executed in two or more counterparts, each of which
shall be deemed an original and all of which together shall constitute one and
the same instrument.

     29.19 MODIFICATION, AMENDMENT, SUPPLEMENT, OR WAIVER

     No modification, amendment, supplement to, or waiver of the Agreement or
any of its provisions shall be effective and binding upon the Parties unless it
is made in writing and duly signed by the Parties. A failure or delay of either
Party to enforce any of the provisions hereof, to exercise any option which is
herein provided, or to require performance of any of the provisions hereof shall
in no way be construed to be a waiver of such provisions or options.

     29.20 SUCCESSORS AND ASSIGNS

     This Agreement shall be binding on and inure to the benefit of the Parties
and their respective legal successors and permitted assigns.

     29.21 PUBLICITY AND USE OF TRADEMARKS OR SERVICE MARKS

     Neither Party nor its subcontractors or agents shall use the other Party's
trademarks, service marks, logos or other proprietary trade dress in any
advertising, press releases, publicity matters or other promotional materials
without such Party's prior written consent.

     29.22 RESTRUCTURED/NEW RATES

     Nothing in this Agreement shall affect or limit (i) BA's right to introduce
a new element or service not offered to NCI under this Agreement on the
Effective Date of this Agreement, or (ii) BA's right to modify, restructure or
change an existing element or service and to charge NCI such rates as approved
by the DTE for such modified, restructured or altered element or service. BA
shall be entitled to recover from NCI such new, additional or restructured
rates, charges or prices at such time and subject to such true-up arrangements
as may be ordered or approved by the DTE.

     29.23 INTEGRITY OF NETWORKS 

     The Parties acknowledge that BA, at its election, may deploy fiber
throughout its network and that such fiber deployment may inhibit or facilitate
NCI's ability to provide service using certain technologies. Notwithstanding any
other provision of this Agreement, either Party shall have the right to deploy,
upgrade, migrate and maintain its network at its discretion.

                                                                              68
<PAGE>
 
IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be executed
as of this ______ day of ________, 199__

NORFOLK COUNTY INTERNET, INC.                BELL ATLANTIC - MASSACHUSETTS     
                                                                               
By: _____________________                    By: _______________________
                                                                               
Printed: ________________                    Printed: Jeffrey A. Masoner       
                                                      ------------------
Title: __________________                    Title: Vice President -           
                                                    --------------
                                             Interconnection Services           
                                             ------------------------

                                                                              69
<PAGE>
 
SCHEDULE 1.0

                      CERTAIN TERMS AS DEFINED IN THE ACT

     "Affiliate" means a person that (directly or indirectly) owns or controls,
is owned or controlled by, or is under common ownership or control with, another
person. For purposes of this paragraph, the term "own" means to own an equity
interest (or the equivalent thereof) of more than ten percent (10%).

     "Dialing Parity" means that a person that is not an Affiliate of LEC is
able to provide Telecommunications Services in such a manner that Customers have
the ability to route automatically, without the use of any access code, their
Telecommunications to the Telecommunications Services provider of the Customer's
designation from among two (2) or more Telecommunications Services providers
(including such LEC).

     "Exchange Access" means the offering of access to Telephone Exchange
Services or facilities for the purpose of the origination or termination of
Telephone Toll Services.

     "InterLATA Service" means Telecommunications between a point located in a
local access and transport area and a point located outside such area.

     "Local Access and Transport Area" or "LATA" means a contiguous geographic
area: (a) established before the date of enactment of the Act by a Bell
operating company such that no Exchange Area includes points within more than
one (1) metropolitan statistical area, consolidated metropolitan statistical
area, or State, except as expressly permitted under the AT&T Consent Decree; or
(b) established or modified by a Bell operating company after such date of
enactment and approved by the FCC.

     "Local Exchange Carrier" means any person that is engaged in the provision
of Telephone Exchange Service or Exchange Access. Such term does not include a
person insofar as such person is engaged in the provision of a commercial mobile
service under Section 332(c) of the Act, except to the extent that the FCC finds
that such service should be included in the definition of such term.

     "Network Element" means a facility or equipment used in the provision of a
Telecommunications Service. Such term also includes features, functions, and
capabilities that are provided by means of such facility or equipment, including
subscriber numbers, databases, signaling systems, and information sufficient for
billing and collection or used in the transmission, routing, or other provision
of a Telecommunications Service.

     "Number Portability" means the ability of users of telecommunications
services to retain, at the same location, existing telecommunications numbers
without impairment of quality,

                                                                              70
<PAGE>
 
reliability, or convenience when switching from one telecommunications carrier
to another.

     "Telecommunications" means the transmission, between or among points
specified by the user, of information of the user's choosing, without change in
the form or content of the information as sent and received.

     "Telecommunications Carrier" means any provider of Telecommunications
Services, except that such term does not include aggregators of
Telecommunications Services (as defined in Section 226 of the Communications
Act).

     "Telecommunications Service" means the offering of Telecommunications for a
fee directly to the public, or to such classes of users as to be effectively
available directly to the public, regardless of the facilities used.

     "Telephone Exchange Service" means (a) service within a telephone exchange
within a connected system of telephone exchanges within the same exchange area
operated to furnish subscribers intercommunicating service of the character
ordinarily fumished by a single exchange, and which is covered by the exchange
service charge, or (b) comparable service provided through a system of switches,
transmission equipment, or other facilities (or combination thereof) by which a
subscriber can originate and terminate a telecommunications service.

     "Telephone Toll Service" means telephone service between stations in
different exchange areas for which there is made a separate charge not included
in contracts with subscribers for exchange service.

                                                                              71
<PAGE>
 
SCHEDULE 4.0 NETWORK INTERCONNECTION SCHEDULE

LATA           NCI-IP    BA-IP          Activation Date

                                                                              72
<PAGE>
 
EXHIBIT B

                       NETWORK ELEMENT BONA FIDE REQUEST

     1.   Each Party shall promptly consider and analyze access to a new
unbundled Network Element with the submission of a Network Element Bona Fide
Request hereunder. The Network Element Bona Fide Request process set forth
herein does not apply to those services requested pursuant to Report & Order and
Notice of Proposed Rulemaking 91-141 (rel. Oct. 19, 1992) T 259 and n.603 or
subsequent orders.

     2.   A Network Element Bona Fide Request shall be submitted in writing and
shall include a technical description of each requested Network Element.

     3.   The requesting Party may cancel a Network Element Bona Fide Request at
any time, but shall pay the other Party's reasonable and demonstrable costs of
processing and/or implementing the Network Element Bona Fide Request up to the
date of cancellation.

     4.   Within ten (10) business days of its receipt, the receiving Party
shall acknowledge receipt of the Network Element Bona Fide Request.

     5.   Except under extraordinary circumstances, within thirty (30) days of
its receipt of a Network Element Bona Fide Request, the receiving Party shall
provide to the requesting Party a preliminary analysis of such Network Element
Bona Fide Request. The preliminary analysis shall confirm that the receiving
Party will offer access to the Network Element or will provide a detailed
explanation that access to the Network Element is not technically feasible
and/or that the request does not qualify as a Network Element that is required
to be provided under the Act.

     6.   If the receiving Party determines that the Network Element Bona Fide
Request is technically feasible and otherwise qualifies under the Act, it shall
promptly proceed with developing the Network Element Bona Fide Request upon
receipt of written authorization from the requesting Party. When it receives
such authorization, the receiving Party shall promptly develop the requested
services, determine their availability, calculate the applicable prices and
establish installation intervals.

     7.   Unless the Parties otherwise agree, the Network Element Requested must
be priced in accordance with Section 252(d)(1) of the Act.

     8.   As soon as feasible, but not more than ninety (90) days after its
receipt of authorization to proceed with developing the Network Element Bona
Fide Request, the receiving Party shall provide to the requesting Party a
Network Element Bona Fide Request quote which will include, at a minimum, a
description of each Network Element, the availability, the applicable rates and
the installation intervals.

                                                                               1
<PAGE>
 
     9.   Within thirty (30) days of its receipt of the Network Element Bona
Fide Request quote, the requesting Party must either confirm its order for the
Network Element Bona Fide Request pursuant to the Network Element Bona Fide
Request quote or seek arbitration by the Commission pursuant to Section 252 of
the Act.

     10.  If a Party to a Network Element Bona Fide Request believes that the
other Party is not requesting, negotiating or processing the Network Element
Bona Fide Request in good faith, or disputes a determination, or price or cost
quote, or is failing to act in accordance with Section 251 of the Act, such
Party may seek mediation or arbitration by the Commission pursuant to Section
252 of the Act.

                                                                               2
<PAGE>
 
                                                                      APPENDIX 2

                 SCHEDULE 4.0 NETWORK INTERCONNECTION SCHEDULE

LATA           FOCAL-IP            BA-IP          Activation Date

TBD            TBD                 TBD            TBD

<PAGE>

                                                                Exhibit No. 10.7
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 1


                     AMENDMENT No. 3 TO PRODUCT ATTACHMENT

                           CARRIER NETWORKS PRODUCTS

                                    BETWEEN

                             NORTHERN TELECOM INC.

                                      AND

                       FOCAL COMMUNICATIONS CORPORATION

THIS AMENDMENT No. 3 TO PRODUCT ATTACHMENT, Carrier Networks Products, is dated
effective as of January 1, 1999, (the "Amendment No. 3"), is by and between
Northern Telecom Inc. ("Nortel") and Focal Communications Corporation ("Buyer"),
and amends the Product Attachment, dated January 21, 1997 (the "Product
Attachment"), as amended by Amendment No. 1 to Product Attachment, dated June
10, 1997 (the "Amendment No. 1"), and Amendment No. 2 to Product Attachment,
dated March 6, 1998 (the "Amendment No. 2"), which is attached to the Network
Products Purchase Agreement Number JRD0197FCC, dated January 21, 1997 ("NPPA"),
as amended by Amendment No. 1 to the Network Products Purchase Agreement Number
JRD0197FCC, dated June 10, 1997 ("Amendment No. 1 NPPA"), by and between Nortel
and Buyer;

WHEREAS, the parties wish to amend the Product Attachment, as amended, and the
Schedule A attached thereto to reflect Buyer's new commitment; and

NOW, THEREFORE, for the consideration shown below, the parties hereby amend the
Product Attachment and Schedule A as follows:

1.   Article 1, Incorporation by Reference, is hereby amended to read as
     follows:

     1.   INCORPORATION BY REFERENCE
          --------------------------

     This Product Attachment, as amended, shall be incorporated into and made a
     part of the NPPA by and between Nortel and Buyer.

2.   Article 2, Definitions, is hereby amended to include the following
     definitions:

     "Class 4 Switching Products and Services" shall mean Products and Services
     supporting a toll center or toll point in the North American long distance
     switching hierarchy.

<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 2

     "Class 5 Switching Products and Services" shall mean Products and Services
     supporting an end office, a local central office or exchange in the North
     American hierarchy.

     "Third Party Hardware" shall mean any hardware not of Nortel's manufacture
     which shall be deemed to include any such hardware which Nortel adds to its
     generally available Third Party Hardware price lists or so identifies to
     Buyer.

     "Third Party Software" shall mean any Software not owned by Nortel which is
     included within licensed Software or non-licensed Software.

3.   "Product Attachment Term", as defined in Section 2.0, "Definitions" is
     amended and restated to read:

     "Product Attachment Term" shall mean the period of time commencing upon
     January 1, 1999, and shall expire thirty six (36) months thereafter.

4.   Section 3, entitled "Scope", in the Product Attachment is amended and
     restated as follows:

     (a)  The parties agree that Buyer's Commitment Amount as set forth in
          Section 3 of Amendment No. 2 is hereby deemed satisfied in full for
          all Orders received and accepted by Nortel from Buyer as of December
          31, 1998.

     (b)  Buyer shall issue Orders for delivery and installation of the Products
          listed in the attached Schedule A, in the minimum amount of Twenty
          Five Million Dollars ($25,000,000.00) every twelve (12) months during
          the Product Attachment Term, for a total minimum commitment amount of
          Seventy Five Million Dollars ($75,000,000.00) during the Product
          Attachment Term (the "Commitment Amount").  Buyer shall pay the
          prices, fees and charges for the Products in accordance with Section 7
          of this Product Attachment.

     (c)  In the event that Buyer does not purchase a minimum of Twenty Five
          Million Dollars ($25,000,000.00) in Product every twelve months during
          the Product Attachment Term, Nortel shall invoice annually and Buyer
          shall pay *** of the difference between Twenty Five Million Dollars
          ($25,000,000.00) and the amount actually spent by Buyer during that
          twelve (12) month period of time, within thirty (30) days from the
          date of invoice.

     (d)  In the event that Buyer exceeds the purchase amount of Twenty Five
          Million Dollars ($25,000,000.00) in Product every twelve (12) months
          during the Product Attachment Term, Buyer shall receive an annual
          credit 
- ---------
 **Confidential information omitted pursuant to a request for confidential 
   treatment filed separately with the Securities and Exchange Commission.


<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 3

          to be applied to Buyer's subsequent purchases of any Optional Software
          described in Schedule A, Part III, Section 1.0 and to any Software
          Upgrades described in Schedule A, Part I, Section 1.4, excluding any
          required hardware for feature functionality (the "Software Credit").
          Such Software Credit shall be equal to *** of the dollar amount over 
          and above Twenty Five Million Dollars ($25,000,000.00), ***. Upon the
          expiration of the Product Attachment Term contemplated by this
          Amendment No. 3, all remaining Software Credits shall expire.

     (e)  Buyer may issue Orders for DMS-500 Optional Hardware at Nortel's then
          current prices ("Optional Hardware") and Optional Software, as
          described in the attached Schedule A, Part III, Section 1.0 ("Optional
          Software"), from time to time during the Product Attachment Term.
          Buyer shall receive a *** discount on the prices, fees and charges for
          any DMS-500 Optional Hardware and/or Optional Software Order issued
          prior to the date of shipment for the DMS-500 Initial System upon
          which such DMS-500 Optional Hardware and/or Optional Software will be
          installed. Otherwise, Buyer shall receive a *** discount on the
          prices, fees and charges for any DMS-500 Optional Hardware and/or
          Optional Software Order issued at any other time during the Product
          Attachment Term. Such discounts shall not apply to Third Party
          Hardware and Third Party Software.

     (f)  Buyer shall receive a one (1) time *** discount on the initial
          Merchandise Order issued by Buyer during each quarter during the
          Product Attachment Term, and a *** discount on all subsequent
          Merchandise Orders issued by Buyer during each quarter during the
          Product Attachment Term.

     (g)  No later than November 1st of each year during the Product Attachment
          Term, Buyer shall provide to Nortel a written forecast listing the
          Products that Buyer intends to order for delivery and installation
          during the following twelve (12) months of the Product Attachment Term
          (the "Annual Forecast"). The initial Annual Forecast is set forth in
          the attached Schedule C. Buyer may revise its then-current Annual
          Forecast from time to time, and, upon submission of the revised Annual
          Forecast to Nortel, each such revised Annual Forecast shall supercede
          all Annual Forecasts that were previously submitted to Nortel.

     (h)  Nortel shall perform an in-process and quality audit for each and
          every Initial System purchased and installed hereunder prior to the
          Turnover 
- --------
 **Confidential information omitted pursuant to a request for confidential 
   treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 4

          Date as described in Section 8 of this Product Attachment. Also,
          Nortel shall perform a quality audit for each and every Extension
          purchased and installed hereunder prior to the Turnover Date.

     (i)  During the Product Attachment Term, Buyer shall purchase from Nortel
          all of Buyer's requirements for "Class 4" and "Class 5" switches (as
          those terms are used in the telecommunications industry), except that
          Buyer shall be relieved of Buyer's obligation to purchase its
          requirements for "Class 4" and "Class 5" switches in the event that
          Buyer acquires or merges with an entity which, at the time of the
          merger and acquisition, operates "Class 4" and "Class 5" switches not
          manufactured by Nortel.

     (j)  In the event that Nortel, through no fault other than its own, fails
          to effect Turnover of an Initial System no later than one hundred
          twenty (120) days after the date upon which the Installation Services
          commenced, Nortel shall pay to Buyer, as liquidated damages and not as
          a penalty, and as Buyer's sole and exclusive remedy, the amount of
          *** per day for each day that Turnover is delayed beyond such one
          hundred twentieth (120th) day. In no event shall Nortel's liability
          under this provision exceed *** for each Initial System ordered by
          Buyer hereunder.

     (k)  Buyer may issue an Order for Extension Ports in the increments set
          forth and as described in Schedule A, Part IV, Sections 1.1 and 1.3,
          during the Product Attachment Term ("Extension Ports").  If Buyer
          issues an Order each calendar year during the Product Attachment Term
          for such Extension Ports and Nortel receives such Order between
          January 1st and June 30th, Buyer shall receive a five percent (5%)
          discount off the price of each Extension Port increment.  Nortel shall
          issue an invoice for each Extension Port Order upon the earlier of (i)
          date of shipment of such Order, or (ii) December 1st of that calendar
          year, and Buyer shall pay the invoiced amount within thirty (30) days
          after the date of invoice.  If Buyer fails to pay such invoice within
          thirty (30) days after the date of invoice, Nortel shall add the five
          percent (5%) discount back into the price of the Extension Ports and
          issue an additional invoice for payment of such five percent (5%) of
          the purchase price of the Extension Ports.  All Extension Port Orders
          issued by Buyer and received by Nortel after June 30th of a calendar
          year shall be subject to the pricing set forth in Schedule A, Part IV,
          Section 1.3. Buyer shall pay the prices, fees and charges for the
          Extension Ports ordered after June 30th of a calendar year, in
          accordance with Section 7 of this Product Attachment.
- --------
 **Confidential information omitted pursuant to a request for confidential 
   treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 5

     (l)  If Buyer purchases a DMS Initial System during the Product Attachment
          Term of this Agreement and Nortel, within ninety (90) days after the
          Turnover Date of such DMS Initial System, makes generally available to
          its customers a more current NCS (Local Side Only) DMS Software load
          release ("New Software Load"), Buyer may notify Nortel that Buyer
          desires to upgrade such DMS Initial System to the New Software Load.
          Nortel shall install the New Software Load upon Buyer's DMS Initial
          System ordered within the previous ninety (90) days only at no
          additional charge; provided, that Buyer issues an Order for
          installation of and pays the licensing fees and applicable charges for
          the New Software Load upgrade for Buyer's entire network of DMS
          systems.  Nortel will invoice and Buyer shall pay for any additional
          Hardware required to upgrade the DMS Initial System and Buyer's
          network to the New Software Load. Buyer shall pay all prices, fees and
          charges in accordance with Section 7 of this Product Attachment.

     (m)  Buyer may issue a written Order for a trial license of the DMS-500
          Software SOC Features as described in Schedule A, Part III, Section
          1.0 ("Software SOC Features"), for a period of thirty (30) days from
          the parties' mutually agreed to date of commencement of the trial
          ("Trial Period") upon a DMS-500 Initial System at Buyer's facilities
          ("SOC Trial"). The following additional terms and conditions shall
          apply:

          1.   The SOC Trial shall not be used by Buyer for generating or
               producing revenue and shall only be used for the purpose of
               testing features and/or services which Buyer may wish to deploy
               in its network.  In the event that Buyer uses any and/or all of
               the Software SOC Features during the SOC Trial for the purpose of
               producing revenue at any time during the Trial Period, Nortel
               shall invoice Buyer, and Buyer shall pay to Nortel within thirty
               (30) days of the date of such invoice Nortel's then current
               Software licensing fees for the Software SOC Features installed
               upon the applicable DMS-500 Initial System.

          2.   Nortel will license to Buyer during the Trial Period any
               additional Software features required for the Software SOC
               Features functionality during the SOC Trial.

          3.   Upon the expiration of the SOC Trial, Buyer shall provide Nortel
               with written notice of Buyer's intent to continue to license or
               discontinue to license and use the Software SOC Features.  If
               Buyer's intent is to continue the license of the Software SOC
               Features or if Buyer fails to notify Nortel of Buyer's intent
               upon the expiration of the Trial Period, Nortel shall invoice and
               Buyer 

<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 6

               shall pay the licensing charges and fees for the Software SOC
               features within thirty (30) days after the date of invoice. If
               Buyer's intent is to discontinue the license, Buyer shall grant
               Nortel access to the DMS-500 Initial System to terminate Buyer's
               license and use of such Software SOC Features.

          4.   Title to the Software SOC Features shall remain solely and
               exclusively vested in Nortel and Buyer's rights therein shall be
               limited to a right to use such Software SOC Features in
               accordance with the terms of the Software License set forth in
               Section 10 only for as long as Buyer uses the DMS-500 Initial
               System.

          5.   Nortel shall be granted access to the DMS-500 Initial Systems
               upon a monthly basis for the purpose of polling the Software that
               Buyer is operating upon such Systems.

5.   Section 11, entitled "Additional Terms", in the Product Attachment is
     amended and restated as follows:

     (c)  In the event that Nortel elects to discontinue the manufacture of any
          Product described in the attached Schedule A at any time during the
          seven (7) years following the Turnover Date of each Initial System
          ordered hereunder, then Nortel shall provide Buyer with written notice
          of such discontinuance at least twelve (12) months prior to the
          scheduled date of such discontinuance.  During the twelve (12) month
          period following Buyer's receipt of such notification from Nortel,
          Buyer may order and Nortel shall deliver as much of the Products
          described in the attached Schedule A as Buyer reasonably requires at
          the then current prices and/or licensing fees.  Nothing herein shall
          be construed so as to require Nortel to continue to manufacture any
          Products described in the attached Schedule A.

     (d)  Deleted.

6.   All provisions of Schedule A as attached to the Product Attachment are
     hereby deleted and replaced with the Schedule A attached hereto.

7.   Schedule C to the Product Attachment is hereby deleted and replaced with
     the Schedule C attached hereto.

<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                                          Page 7

Except to the extent modified herein, all other terms and conditions of the
Product Attachment shall remain unchanged and in full force and effect.

NORTHERN TELECOM INC.                  FOCAL COMMUNICATIONS
                                       CORPORATION


By: /s/ Richard G. Reid                By: /s/ John R. Barnicle
   --------------------------------       --------------------------------
              Signature                              Signature


Name: /s/ Richard G. Reid              Name: /s/ John R. Barnicle
     ------------------------------         ------------------------------
                 Print                                  Print


Title: /s/ President - Global          Title: E.V.P. - C.O.D.
           Carrier Sound                     -----------------------------
      -----------------------------          


Date:  3/25/99                         Date:  3/25/99
     ------------------------------         ------------------------------

<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 1


                                  Schedule A
                        Part I. DMS-500 Initial System
                          (DMS-500 Switching System)

Nortel shall engineer each Initial System ordered hereunder in accordance with
Nortel's standard engineering practices and procedures, and thereafter Nortel
shall provide Buyer with a detailed list of the components of such Initial
System.

1.0  Initial System DMS-500

     1.1  The following represents the SuperNode Equipment that will be
          delivered with the Initial System DMS-500 switch:

          . One (1) SuperNode equipped with BRISC-70EM and three (3) additional
            memory cards per plane along with a spare NT9X14EA.

          . One (1) Two-frame 128k ENET provisioned to support the proposed
            switch configuration and three (3) CCTS 128K fiber management bays.

          . One (1) Link Peripheral Processor (LPP)
            . Eight (8) Channelized Access (LUI - NTEX26AA) links for SS7
            . Two (2) Network Interface Unit (NIU)
            . One (1) XLIU
            . One (1) EIU NT9X84AA - Ethernet interface card, One (1) NT9X85AA -
              Ethernet AUI paddleboard, One (1) NTEX22BB - Integrated Processor,
              NT9X0190 - Cable for above cards, B0229786 - Cable for above cards

          . Thirty (30) Digital Trunk Equipment ISDN (DTEI) frames
            . Twenty-two (22) Digital Trunk Controller (DTC7) modules Wired and
              Equipped for 10,560 Local SS7 ports.
            . Thirty-eight (38) Digital Trunk Controller ISDN (DTCI) modules
              for local PRI trunks Wired and Equipped for 18,240 ports.

          . Three (3) Multi-Vendor Interface Equipment (MVIE) frames
            . Six (6) SMA2 modules Wired and Equipped for 480 TR-303 ports per
              module (2,880 total) to provide host-remote interface for Nortel
              AccessNode/AccessNode Express.
            . Class Modem Resources (CMR) packs for each module.
            . ISDN Ready.
            . (2) D-Channel Handlers per SMA2.

          . All peripherals are equipped with XPM+ hardware.

          . One (1) Input Output Equipment (IOE) frames equipped with:
            . One (1) 2 GB Distributed Processing Peripheral (DPP)

          . Two (2) IOM modules each equipped with One (1) DAT, Two (2) DDU,
            Two (2) Storage Media cards and four (4) I/O controllers supporting
            16 input output ports.

          . Two (2) MISC frame equipped with (4) 500W inverters, 1 GDC rack
            mounted modem shelf, and 3 rack mounted modems dedicated for 
            Northern Telecom use.


               Proprietary and Confidential Information of Nortel
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 2

                                  Schedule A
                        Part I. DMS-500 Initial System
                          (DMS-500 Switching System)


          . Three (3) ISME frames equipped with standard DMS-500 test and
            maintenance circuit packs, including, eight (8) Enhanced digital
            Recorded Announcement Machines (EDRAMs), four (4) Conference Trunk
            Modules (CTMs) along with the following quantity of service
            circuits:
<TABLE>
<CAPTION>

          NTPEC       DESCRIPTION                      DMS-500 STANDARD      REQUIRED
<S>                   <C>                              <C>                   <C>
          NT0X10AA    Misc Scanner                              5                7
          NT1X54AA    Jack Ended Trunk LOC 2W22                 2                4
          NT1X80AA    102 Test                                  1                2
          NT2X10BB    Multi-Line test Unit                      1                2
          NT2X11BA    Multi-line Tst Un CTL CAR                 1                2
          NT2X48BA    DIG 4 CH MF REC                           1                1
          NT2X57AA    SD Card 1                                 2                5
          NT2X71AA    Transmission Term                         Optional         4
          NT2X72AA    4W E&M type 1 Interf 600                  2                4
          NT2X75AA    Loop ground Test Line                     1                1
          NT2X81AA    TRK 2W E&M 900 OHM                        1                1
          NT2X90AD    Incoming / Outgoing Test                  4                4
          NT3X09BA    8*8 Matrix CP                             1                2
          NT3X68AB    DTMF                                      1                1
          NT3X68AC    CWT                                       2                2
          NT3X82AH    OAU Dead SYS Alarm                        2                2
          NT3X83AC    OAU Alarm Transfer                        1                1
          NT4X45AA    Enhanced DTU                              6                5
          NT5X29AC    CTS Tone Det DTMF Tone Ge                 1                1
          NT5X30BA    Comm Trunk T101                           3                4
</TABLE>

          . One (1) Meridian Cabinet Spare Storage (MCSS) cabinet to house
            switch spares.

          . Three (3) Power Distribution Center (PDC) frame equipped with "A"
            and "B" feed fuse panels & fuses as required.

          . Miscellaneous Switch Room Equipment as follows:
            . Two (2) Maintenance and Administration Position (MAP)
            . Two (2) VDU terminals
            . Two (2) RTIF terminals
            . Two (2) MAP printer
            . Two (2) MAP furniture
            . Three (3) sets of documentation on CD-ROM disk

          . Two (2) M5317-TX (B0249893-NTWA00BA) and two (2) NT-1 interfaces
            (TEC01910-NTBX80CA) for ISDN line testing.

          . Nortel will provide ADC - 84 PW DSX panels and Relay Rack Equipment
            to support the switch side termination of the DMS-500. Cables need
            to be stitched at DSX. Six (6) Inch Relay Rack Spacers will be
            provided.

          . Nortel Modular MDF Frame (Part # 689-2075-103; Brown - CPC A0337718)
            to support the above configuration.


              Proprietary and Confidential Information of Nortel
<PAGE>

                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 3

                                  Schedule A
                        Part I. DMS-500 Initial System
                          (DMS-500 Switching System)
 
          . (100) person days of selectable training.

          . Standard DMS-500 Software load as set forth in Part II or the most
            currently, generally available load.

          . Nortel's standard compliment of one (1) spare per unique circuit
            pack for the DMS-500 Initial System and a total of ten (10) Data
            Cartridges and five (5) Filters per Frame with a cooling unit.

     1.2  Initial System DMS-500

          The price for the Initial System DMS-500 equipped and wired as
          described in Section 1.1 above, and the Standard Software licensing
          fee is ***.

     1.3  Power Plant to support the above DMS-500 Initial System (Optional):

          1.3.1  Power Plant

          The Power Plant includes batteries, rectifiers, power board equipment.
          Power plant sized at an initial load of 1200 Amps, per Buyer request.
          Battery strings are provisioned for a four (4) hour reserve period.
          The Power Plant provided meets both Seismic and Non-Seismic
          requirements.

          Nortel will provide a 480VAC Power Plant and Batteries as outlined in
          Power quote PED08154.4. In addition, per contract, two (2) new version
          BDFB are to be provided with 20-20 amp fuses and 20-30 amp fuses.
          Battery disconnects (one (1) per string), low voltage disconnect and
          an Infrared scan will be performed.

          The price for the Power Plan (PED08154.4) is ***.

          1.3.2  Battery Distribution Fuse Bay

          The price for two (2) Battery Distribution Bays ("BDFB") is *** in
          addition to the above power quote.

              Proprietary and Confidential Information of Nortel 

- --------
*** Confidential information omitted pursuant to a request for confidential 
treatment filed separately with the Securities and Exchange Commission.
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 4

                                  Schedule A
                        Part I. DMS-500 Initial System
                          (DMS-500 Switching System)
         
     1.4  Software Upgrades for the  DMS-500 Initial System (Optional):

          The following prices for DMS-500 Software Upgrades do not include
          Gating Hardware. However, the prices do include Engineering and
          Installation for the Software Upgrade. If Buyer does not purchase
          Software Upgrades that maintain the CSP load within three (3) Software
          loads of the most current Software load, a re-certification charge
          will be accessed upon Buyer's Order the next Software Upgrade.

          1.4.1 The price for the NCS09 (LLT00009-Local/Toll) to NCS10 
                (LLT00010-Local/Toll)Generic Software Upgrade is ***.

          1.4.2 The price for the NCS09 (LLT00009-Local/Toll/LD) to NCS10 
                (LLT00010-Local/Toll/LD) Generic Software Upgrade is ***.

          1.4.3 The price for the NCS09 (LLT00009-Local/Toll) to NCS11 
                (LLT00011-Local/Toll) Generic Software Upgrade is ***.

          1.4.4 The price for the NCS09 (LLT00009-Local/Toll/LD) to NCS11 
                (LLT00011-Local/Toll/LD) Generic Software Upgrade is ***.

          *Sections 1.4.1 through 1.4.4 reference Weekday one night processing
          fee ("ONP"). If the Software upgrade is scheduled for a Weekend ONP,
          depending on availability, the price will increase by ***.


              Proprietary and Confidential Information of Nortel 

- -------
*** Confidential information omitted pursuant to a request for confidential 
treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 5

                                  Schedule A
                  Part II. DMS-500 Standard Software Features


1.0  DMS-500  Standard Software Features

     1.1  Nortel may deliver Software ordered hereunder in a single Software
          load which may include Software which Buyer has not yet licensed 
          ("Non-licensed Software"). Except as set forth in Section 1.2 below,
          Buyer shall not be entitled to use such Non-licensed Software, until
          such time as the applicable right to use fees are paid by Buyer
          pursuant to Section 1.5.

     1.2  Upon Buyer's placement of any Non-licensed Software in revenue
          generating service, Buyer shall pay the applicable right-to-use fees
          for such Non-licensed Software pursuant to this Agreement, except as
          described in Section 1.2. Buyer shall also have the option to pay the
          applicable right-to-use fees for any Non-licensed Software upon
          installation of a Software load containing such Non-licensed Software.
          For any Non-licensed Software that is installed and added pursuant to
          a product computing module load ("PCL") and or non-computing module
          load ("NCL"), if any, the right-to-use fees shall be the list price
          for such feature in effect as of the date of activation.

     1.3  To ensure Buyer's proper activation and/or usage of the appropriate
          Software, Buyer shall properly notify Nortel at the address specified
          in Section 9 of this Product Attachment to the attention of Director,
          Sales Engineering, prior to the activation and/or usage by Buyer of
          any Software. Buyer shall identify all Software being activated and/or
          used (including the number of units activated, if applicable) in each
          Initial System.

     1.4  Nortel shall promptly review notification from Buyer provided pursuant
          to Section 1.4 above and identify any applicable prerequisite
          Equipment or Software required by Buyer prior to activation and/or
          usage of the applicable Software. Nortel shall respond to Buyer's
          written notice by means of a price quotation. Such price quotation
          shall include Nortel's consent to activate and/or use such Software or
          notification that such Software requires engineering to determine
          whether the current switch configuration will require additional
          Equipment prior to activation and/or usage. Upon Buyer's written
          acceptance of Nortel's price quotation, Nortel shall grant its consent
          to Buyer to activate and/or use such Software prior to payment of the
          applicable right-to-use fees. However, under no circumstances shall
          such Software be activated and/or used by Buyer prior to Buyer's
          acceptance of Nortel's price quotation. Nortel shall invoice Buyer for
          all applicable right to use fees and associated feature activation
          engineering charges. One hundred percent (100%) of such invoiced right
          to use fees and engineering charges shall be due and payable within
          thirty (30) days of the date of Nortel's invoice therefor.

     1.5  Notwithstanding the foregoing, Buyer shall not be required to pay
          additional right to use fees associated with the Software licensed
          prior to the initial date of this Product Attachment.

     1.6  Nortel reserves the right, every six (6) months to submit a written
          report for each site containing a Software load. The written report
          shall identify all Software activated and/or used (including the
          number of incremental units activated, if applicable) by Buyer during
          the applicable reporting period. Buyer shall audit the report against
          Purchase Order(s) which have been submitted by Buyer and accepted by
          Nortel during the applicable period to determine the existence of any
          discrepancies. Buyer shall submit such audited written report to
          Nortel at the address specified in Section 9 of this Product
          Attachment to the attention of Director, Sales Engineering, within
          thirty (30) days from receipt of such request.

     1.7  Nortel also reserves the right to access by remote polling or to
          conduct an on-site inspection of any site in which a Software load is
          installed and/or to perform an on-site review of Buyer's books and
          records related to such site to verify activation and/or usage of
          Software.

              Proprietary and Confidential Information of Nortel 
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 6
                                  Schedule A
                  Part II. DMS-500 Standard Software Features

     1.8  Nortel shall issue invoices, for any applicable prices, charges or
          fees, in addition to those amounts previously invoiced, as a result of
          Buyer's activation and/or usage of any Software that does not appear
          on Nortel's written report or that appear as a result of Nortel's
          remote polling of an Initial Systems.

     1.9  Upon payment of the applicable right to use fees for Software
          activated and/or used by Buyer, Buyer shall receive a non-exclusive
          paid-up license to use such Software in accordance with the provisions
          of this Agreement. Nortel may immediately terminate the applicable
          license granted hereunder for Buyer's failure to pay the applicable
          right to use fees for such Software which has been activated and/or
          used.

     1.10 The obligations of Buyer under this Section 1 shall without limitation
          survive the termination of this Agreement and shall continue if the
          Software is removed from service. Buyer agrees to indemnify Nortel or
          Third Party Software Vendors as appropriate for any loss or damage
          resulting from a breach of this Section 1.


              Proprietary and Confidential Information of Nortel 
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 7

                                  Schedule A
                  Part II. DMS-500 Standard Software Features

2.0  LLT00010 Software included in the DMS-500 Initial System
2.1  Software included in the DMS-500 Initial System
The following represents the LLT00010 Software packages that are included in the
price of the DMS-500 Initial System, described in Schedule A, Part 1, Section
1.0. The following is a list of Software only and does not include any/all
required Equipment to provide feature functionality.

             S/W Package      Description
             -----------      -----------
               AIN00026       AIN Translation Simplification (Note 1)
               BAS00001       Base Cook
               BAS00002       Base ANI
               BAS00003       Base Generic
               BAS00004       Base OA&M
               BAS00007       Base Logs
               BAS00020       Base Flexible Bellcore AMA
               BAS00028       Base DPP
               BASE0001       Local Base
               BASE0009       Base SN SR70
               EQA00001       Equal Access Local
               EQA00006       EQA C7ISUP InterLATA Connect-EO
               EQA00008       EQA POTS IntraLATA Prim.I/LATA Carr. EAEO
               ISP700001      ISUP BASE
               LOC00001       Local Services
               LNP00100       LRN Software (Note 1)
               MDC00001       MDC Base  (100 Lines)
               MDC00003       MDC Standard
               NI000007       NIO ISDN Base (1100 ISDN lines, 1050 2B+D lines)
               NI000008       NI0 NI-1 BRI
               NI000009       NI0 NI-1 BRI Enhanced Maintenance
               NI000010       NI0 NI-1 Packet Services
               NI000011       NI0 NI-1 PRI
               NI000022       NI0 ISDN PRI Base
               NI000030       CNAM on PRI (80 T1's) (Note 2)
               NPE00001       Numbering Plan Evolution 1
               NPE00002       Numbering Plan Evolution 2
               NPRI0001       PRI Network Interface
               NTS00005       NTSE 800
               NTS00023       800 Expansion (888)
               RES00003       RES Disp Funct & Prvcy  (for 100 lines)
               RES00004       RES MDC Vice Mail
               RES00006       RES RES Service Enablers
               RES00022       RES Calling Name Delivery Blkng
               RES00023       RES Calling Name Disp SW/TCAP (for 100 lines)
               TEL00001       Telecom Layer
               TEL00002       TEL CCS7 Channelized Access
               TEL00008       CCS7 Base
               UDD00001       UDD Services
               WLC00001       World Line Card Enhanced
               TEL00004       TEL C7 Routset Increment (unlimited usage)
Note 1:  AIN00009, AIN00002, AIN00006, and AIN00007 at no charge for LNP0100 and
AIN translation simplification use only. Chargeable upon use for non-LNP0100 
usage or non-AIN00026 AIN usage.

Note 2:  Prerequisite Software for NI000030 (80 T1's) provided at no additional 
charge


              Proprietary and Confidential Information of Nortel 
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                               Schedule A/Page 8

                                  Schedule A
                 Part III. DMS-500 Optional Software Features
 

<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                              Schedule A/Page 20

                                  Schedule A
                          Part IV. DMS-500 Extensions


     1.0  DMS-500  Extension Pricing

     1.0  DTCI/DTC7 Port Extension Pricing

          1.1  DTCI/DTC7 Port Extension Pricing

               The DTCI provides DS-1 interconnect for ISDN PRI or MF Trunking.
               The DTC7 provides DS-1 interconnect for SS7 or MF trunking. Each
               DTCI/DTC7 Port Extension is configured in minimum increments of
               nine hundred sixty (960) ports and for SS7 or ISDN signaling at
               Buyer's request. The price for the DTCI/DTC7 Port Extensions
               includes the following:

               a.)  DTCI/DTC7 Equipment and XPM;

               b.)  Either UTR, STR, CTD as required for DTCs configured for
                    SS7, or UTR and ISDN pre-processor circuit pack configured
                    for ISDN PRI capability;

               c.)  Any required ENET, MS;

               d.)  Any required DMS-500 service/test circuits to support the
                    DTCI/DTC7 Port Extensions;
 
               e.)  Power Distribution Center (PDC) equipment as required to
                    support the DTEI Port Extensions;

               f.)  Spare circuit packs if required;

               g.)  Wired ports contain all of the above except the DS-1 circuit
                    packs; and

               h.)  Associated NI00011, NI00022 and TEL0004 Software usage.

          1.2  Add-on Port Prices

               Additional DTC7/DTCI ports may be ordered and installed with an
               Initial System for the following listed prices:
<TABLE>
<CAPTION>
                                               Minimum Port      Price per
               Description                       Increment          Port
               -----------                     ------------      ---------
<S>                                            <C>               <C>

               DTC7 ports Wired & Equipped          960             $*** 

               DTCI ports Wired & Equipped          960             $*** 
</TABLE>

**NOTE: DTC7/DTCI Add-On Port pricing is effective for *** after the Turnover
Date of the DMS Initial System.


              Proprietary and Confidential Information of Nortel 

- -------
*** Confidential information omitted pursuant to a request for confidential 
treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 

                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                              Schedule A/Page 21

                                  Schedule A
                          Part IV. DMS-500 Extensions


          1.3  Extensions Port Prices

               Buyer may issue an Order for DTCI/DTC7 Port Extensions in minimum
               increments of 4800 ports and after Buyer has issued its Order for
               an Initial System. Buyer may purchase the DTCI/DTC7 Port
               Extensions as follows:
<TABLE>
<CAPTION>
                                             Minimum Port     Price per
               Description                    Increment         Port
               -----------                    ---------         ----
               <S>                           <C>              <C>
               DTC7 ports Wired & Equipped       4800           $***  

               DTCI ports Wired & Equipped       4800           $***
</TABLE>

               Buyer may issue an Order for DTCI/DTC7 Port Extensions in minimum
               increments of 960 Port Extensions and up to 3840 Port Extensions
               and after Buyer has issued its Order for an Initial System. Buyer
               may purchase these DTCI/DTC7 Port Extensions at the price of $***
               per port.

     2.0  SMA2 Port Extension Pricing

          2.1  SMA2 Ports

               The SMA2 provides DS-1 interconnect for TR-303 interface. Each
               SMA2 Port Extensions is configured in minimum increments of nine
               hundred sixty (960) ports. SMA2 is only available on DMS-100 and
               DMS-500 systems. The price for an SMA2 Port Extension includes
               the following:

               a)   SMA2  Equipment;

               b)   Any required ENET, MS;

               c)   Any required DMS-500 service/test circuits to support the
                    SMA2 Extensions;

               d)   Power Distribution Center (PDC) equipment as required to
                    support the SMA2 Extensions;

               e)   Spare circuit packs if required; and

               f)   Wired ports contain all of the above except the DS-1 circuit
                    packs.

          2.2  Add-on Port Prices
               Additional SMA2 ports may be ordered and installed with an
               Initial System at the following prices:

<TABLE>
<CAPTION>
                                              Minimum Port    Price per
               Description                     Increment        Port
               -----------                     ---------        ----
               <S>                            <C>             <C>
               SMA2 ports Wired & Equipped        960           $***
</TABLE>
          2.3  Extension Port Prices

               Buyer may issue an Order for SMA2 Extension Ports in increments
               of 1,920 ports after Buyer has issued its Order for an Initial
               System for the following prices:

              Proprietary and Confidential Information of Nortel

- -------
*** Confidential information omitted pursuant to a request for confidential 
treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                              Schedule A/Page 22

                                  Schedule A
                          Part IV. DMS-500 Extensions

<TABLE>
<CAPTION>
                                                Minimum Port   Price per
               Description                       Increment        Port
               -----------                       ---------        ----
               <S>                              <C>            <C>
               SMA2 ports Wired & Equipped         1920          $160

               SMA2 ports Wired & Equipped          960          $179
</TABLE>
          3.0  Link Peripheral Processor (LPP)

               3.1  Initial Channelized Access LIU 7 Interface Unit Pricing

                    Additional Channelized Access LIU7 Interface Units may be
                    Ordered and Installed with an Initial System for the price
                    of Eight Thousand Nine Hundred Dollars ($8,900.00) per unit.
                    Channelized Access LIU7 Interface Unit consists of the
                    following:

<TABLE>
<CAPTION>

               Qty   PEC         Description
               ---   ---         -----------
               <S>   <C>         <C>
                1    NTEX22BB    IPF Integrated Proc & FBUS
                1    NT9X76AA    STP- Signalling Terminator CP
                1    NTEX26AA    LUI Channel Bus I/F
                1    NT9X0193    STP Bulkhead Cable Assembly
</TABLE>

               3.2  Extension Channelized Access LIU 7 Interface Unit Pricing

                    Channelized Access LIU7 Interface Units may be Ordered
                    at any time other than with an Initial System for the price
                    of Twelve Thousand Five Hundred Dollars ($12,500.00) per
                    unit. This price is for furnish only and does not include
                    spares.

               3.3  Initial Ethernet Interface Unit Pricing

                    Additional Ethernet Interface Units may be Ordered and
                    Installed with the Initial System for the price of Four
                    Thousand Seven Hundred Forty-Seven Dollars ($4,747.00)
                    per unit. Ethernet Interface Unit consists of the
                    following:

<TABLE>
<CAPTION>

               Qty   PEC         Description
               ---   ---         -----------
               <S>   <C>         <C>
                1    NTEX22BB    IPF Integrated Proc & FBUS
                1    NT9X84AA    Ethernet Interface Circuit Pack
                1    NT9X85AA    Ethernet Access Unit Interface PB
                1    NT9X0190    Ethernet Cable Assembly
</TABLE>

               3.4  Extension Ethernet Interface Unit Pricing

                    Ethernet Interface Units may be Ordered at any time other
                    than with an Initial System for the price of Six Thousand
                    Nine Hundred Forty-Eight Dollars ($6,948.00) per unit. This
                    price is for furnish only and does not include spares.

              Proprietary and Confidential Information of Nortel

<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                              Schedule A/Page 23
                                  Schedule A
                          Part IV. DMS-500 Extensions


          3.5  Initial Frame Relay Interface Unit (FRIU) Pricing

               Additional Frame Relay Interface Units may be Ordered and
               Installed with the Initial System for the price of Eleven
               Thousand Four Hundred Ninety-Four Dollars ($11,494.00) per unit.
               Price does not include software. Frame Relay Interface Unit
               consists of the following:
<TABLE>
<CAPTION>
 
               Qty   PEC        Description
               ---   ---        -----------
<S>                  <C>        <C>
                1    NTEX22BB   IPF Integrated Proc & FBUS
                1    NTEX30AA   Frame Relay T1 Access PB
                1    NTEX31BA   Frame Enhanced Relay Access Proc CP
                2    NT9X0191   FRIU Cable Assembly
</TABLE>

          3.6  Extension Frame Relay Interface Unit  (FRIU) Pricing

               Frame Relay Interface Units may be Ordered at any time other than
               with an Initial System for the price of *** per unit. This price
               is for furnish only. Pricing does not include spares or software.

          3.7  Initial Packet Handler (XLIU) Pricing 

               Additional Packet Handlers may be Ordered and Installed with the
               Initial System for the price of *** per unit. Price does not
               include software. Packet Handler consists of the following:
<TABLE>
<CAPTION>
 
               Qty   PEC        Description
               ---   ---        -----------
<S>                  <C>        <C>
                1    NTEX22BB   IPF Integrated Proc & FBUS
                1    NTFX09AA   CBUS Interface PB
                1    NTFX10AA   HDLC Frame Processor CP
</TABLE>

          3.8  Extension Packet Handler (XLIU) Pricing

               Packet Handler may be Ordered at any time other than with an
               Initial System for the price of *** per unit. This price is for
               furnish only. Pricing does not include spares or software.

          3.9  Initial Network Interface Unit (NIU) Pricing

               Additional Network Interface Units may be Ordered and Installed
               with the Initial System for the price of *** per unit. Network
               Interface Unit consists of the following:
<TABLE>
<CAPTION>

               Qty   PEC        Description
               ---   ---        -----------
<S>                  <C>        <C> 
</TABLE> 

              Proprietary and Confidential Information of Nortel

- ----------------
*** Confidential information omitted pursuant to a request for confidential
treatment filed separately with the Securities and Exchange Commission.
<PAGE>
 
                                                      Focal Communications, Inc.
                                    Amendment No. 3 (1999) to Product Attachment
                                                      Carrier Product Attachment
                                                              Schedule A/Page 24

                                  Schedule A
                          Part IV. DMS-500 Extensions


<TABLE> 
<CAPTION> 
<S>                 <C>        <C> 
               2    NTEX22BB   IPF Integrated Proc & FBUS
               1    NTEX25AA   Channel Bus Control Unit
               1    NTEX25BA   Channel Bus Control Unit
               2    NTEX28AA   DS30 Link Interface Unit
               4    NT9X7020   NIU DS30 Cable Assemblies
               2    NT9X7021   NIU Inter CBC Cable
</TABLE>
          3.10  Extension Network Interface Unit (NIU) Pricing

                Network Interface Unit may be Ordered at any time other than
                with an Initial System for the price of *** per unit. This price
                is for furnish only.

              Proprietary and Confidential Information of Nortel

- ----------------
*** Confidential information omitted pursuant to a request for confidential
treatment filed separately with the Securities and Exchange Commission.
<PAGE>
 
                                                                           Focal
                                           Amendment No. 3 to Product Attachment
                                                       Carrier Networks Products
                                                               Schedule C/Page 1
 
                                  SCHEDULE C
                                  ----------

                           SWITCH DELIVERY FORECAST
                           ------------------------

<TABLE>
<CAPTION>
Switch Type/#      Destination       Delivery Date      Ports      Purchase
- -------------      -----------       -------------      -----      --------
                                                                    Price*
                                                                    ------
<S>                <C>               <C>                <C>        <C>
Extension/ (1)     Chicago, IL       January 1999        9,600       $***
                                                                 
Extension/ (1)     New York          January 1999        9,600       $***
                                                                 
DMS-500/ (1)       Dallas, TX        February 1999      31,680       $***
                                                                 
DMS-500/ (1)       Cambridge, MA     March 1999         18,240       $***
                                                                 
DMS-500/ (1)       New Jersey        March 1999         31,680       $***
                                                                 
DMS-500/ (1)       Atlanta, GA       3rd Quarter 1999   31,680       $***
                                                                 
DMS-500/ (1)       Houston, TX       3rd Quarter 1999   31,680       $***
                                                                 
DMS-500/ (1)       TBD               4th Quarter 1999   31,680*      $***
                                                                 
Extension/ (3)     TBD                     1999                      $***
                                                                 
DMS-500/ (2)       TBD                     2000         31,680*      $***
                                                                 
Extension/ (10)    TBD                     2001                      $
</TABLE>

* Denotes ports and price for each DMS-500 and/or Extension.


VCN21696

- ----------------
*** Confidential information omitted pursuant to a request for confidential
treatment filed separately with the Securities and Exchange Commission.

<PAGE>
 
                                                                  Exhibit 10.8

                               PURCHASE AGREEMENT

         XCOM Technologies, Inc., a subsidiary of Level 3 Communications, Inc.
("XCOM"), and Focal Communications Corporation of Massachusetts ("Focal") hereby
agree as follows:

         1. Certain Definitions.  For purposes of this Agreement the following
terms are hereby defined:

         (a) "Assignment and Assumption"  shall mean the assignment and
         assumption  attached hereto as Exhibit "A."

         (b) "Bill of Sale" shall mean the bill of sale attached hereto as
         Exhibit "B."

         (c) "Closing" shall mean the closing and consummation of the
         transactions described in this Agreement.

         (d) "Co-location Agreement" shall mean the co-location agreement
         attached hereto as Exhibit "C."

         (e) "Com/Energy" shall mean Com/Energy Services Company.

         (f) "Equipment" shall mean that certain equipment described in Exhibit
         "D" attached hereto and located at the Premises.

         (g) "Escrow Agent" shall mean Norwest Bank Colorado, National
         Association.

         (h) "Escrow Agreement" shall mean the escrow agreement attached hereto
         as Exhibit "E."

         (i) "Escrowed Amount" shall mean $2,500,000.00.

         (j) "Facilities Agreement" shall mean that certain Facilities
         Management Agreement dated June 23, 1997, between XCOM and Com/Energy.

         (k) "Landlord" shall mean Riverfront Office Park Associates II Limited
         Partnership.

         (l) "Lease" shall mean that certain Agreement of Lease dated as of July
         1, 1997, and Amendment No. 1 to Agreement of Lease dated February 6,
         1998, and Amendment No. 2 to Agreement of Lease dated May 1, 1998,
         between XCOM and Landlord.

         (m) "New Lease" shall have the meaning set forth in paragraph 7.

         (n) "Premises" shall mean the premises leased by XCOM under the Lease.

         (o) "Purchase Price" shall mean $6,707,864.00.

         2. Purchase and Sale; Assignment. Subject to the terms and conditions
contained herein:
<PAGE>
 
         (a) Focal agrees to purchase from XCOM, and XCOM agrees to sell to
         Focal, the Equipment for the Purchase Price, and

         (b) XCOM agrees to assign to Focal, and Focal agrees to assume from
         XCOM, the Facilities Agreement and all rights, duties and obligations
         thereunder.

         3. Representations of XCOM. XCOM represents and warrants to Focal as
follows, which representations shall survive the Closing:

         (a) XCOM has the power and authority to enter into this Agreement and
         to perform its duties and obligations hereunder.

         (b) There are no proceedings, actions, litigation, bankruptcy
         petitions, judgments or claims of any nature whatsoever pending, or to
         the best of XCOM's knowledge threatened, against XCOM before any court,
         government, regulatory authority or administrative forum which would
         affect the ability of XCOM to observe and perform its duties and
         obligations hereunder.

         (c) XCOM has, or as of the Closing will have, good and marketable title
         to the Equipment free from all liens and encumbrances.

         (d) The Facilities Agreement is in full force and effect, without
         default on the part of XCOM and, to the best of XCOM's knowledge,
         without default on the part of Com/Energy.

         4. Representations of Focal. Focal represents and warrants to XCOM as
follows, which representations shall survive the Closing:

         (a) Focal has the power and authority to enter into this Agreement and
         to perform its duties and obligations hereunder.

         (b) There are no proceedings, actions, litigation, bankruptcy
         petitions, judgments or claims of any nature whatsoever pending, or to
         the best of Focal's knowledge threatened, against Focal before any
         court, government, regulatory authority or administrative forum which
         would affect the ability of Focal to observe and perform its duties and
         obligations hereunder.

         (c) Focal has conducted its own inspections and investigations of and
         with respect to the Equipment and the Facilities Agreement and shall
         acquire the Equipment at the Closing in its "as is" condition and
         without any warranty as to condition, value, utility, use,
         merchantability or fitness for a particular purpose.

         (d) The New Lease (as hereafter defined) shall permit and authorize
         XCOM to use the Premises and operate the Equipment and its own
         equipment as contemplated in this Agreement and the Co-location
         Agreement (the "New Lease")

         5. Closing. The Closing shall occur on January 6, 1999 or such later
date as the parties may mutually agree. In the event the Closing shall fail to
occur on January 6, 1999 and

                                       2
<PAGE>
 
the parties do not mutually agree to extend such Closing date, this Agreement
shall automatically terminate.

         6. Closing Date Transactions. Without limiting paragraph 7 below, at
the Closing the following transactions shall occur:

         (a) XCOM shall execute and deliver the Bill of Sale.

         (b) XCOM and Focal shall each execute and deliver the Assignment and
         Assumption.

         (c) XCOM and Focal shall each execute and deliver the Co-location
         Agreement.

         (d) XCOM, Focal and Escrow Agent shall each execute and deliver the
         Escrow Agreement.

         (e) Any payments owed by Com/Energy under the Facilities Agreement
         shall be prorated between the parties to the Closing.

         (f) Focal shall pay the Purchase Price less the Escrowed Amount (or
         $4,207,864) to XCOM by wire transfer in immediately available funds.

         (g) Focal shall pay the Escrowed Amount to Escrow Agent by wire
         transfer in immediately available funds.

         7. Joint Conditions. Notwithstanding anything in this Agreement to the
contrary, the obligations of XCOM and Focal under this Agreement shall be
subject to satisfaction of each of the following conditions:

         (a) contemporaneous with the Closing, Landlord and Focal shall enter
         into a new lease of the Premises upon terms, and in form, acceptable to
         Landlord and Focal; and

         (b) contemporaneous with the Closing, Landlord and XCOM shall enter
         into a mutual termination of the Lease upon terms, and in form,
         acceptable to Landlord and XCOM.

In the event the foregoing conditions have not been satisfied by January 6,
1999, and such date is not extended pursuant to the mutual Agreement of XCOM and
Focal, this Agreement shall automatically terminate.

         8. XCOM Conditions. Notwithstanding anything in this Agreement to the
contrary, XCOM's obligations under this Agreement shall be subject to the
satisfaction of each of the following conditions:

         (a) all of Focal's  representations  and warranties  shall be true and
         accurate as of the date of Closing; and

         (b) Focal shall have observed and performed all of Focal's covenants
         and agreements contained herein to the date of Closing.

                                       3
<PAGE>
 
         9. Focal Conditions. Notwithstanding anything in this Agreement to the
contrary, Focal's obligations under this Agreement shall be subject to the
satisfaction of each of the following conditions:

         (a) all of XCOM's  representations  and  warranties  shall be true and
         accurate as of the date of Closing; and

         (b) XCOM shall have observed and performed all of XCOM's covenants and
         agreements contained herein to the date of Closing.

         10. Equipment Augmentation. The parties acknowledge that Focal may,
prior to the Closing, order 14,400 or more switch ports respecting the Equipment
(consisting of 7,680 or more DTCI ports and 6,720 or more DTC7 ports). All such
actions relating to augmentation of the Equipment shall be at the sole cost and
risk of Focal and neither XCOM nor its affiliates shall have any liability for
any costs or expenses incurred or associated with such actions if the Closing
fails to occur for any reason. The parties further acknowledge that XCOM may,
prior to the Closing, augment the DACS component of the Equipment. Any such
Equipment augmentation by XCOM shall not affect the Purchase Price.

         11. Casualty. In the event there shall be any loss or damage to the
Equipment by fire or other casualty prior to the Closing, XCOM shall give notice
thereof to Focal, and Focal shall have the option to either waive such event and
proceed to effect the Closing or not waive such event and terminate this
Agreement. If Focal shall elect to effect the Closing, all of the provisions of
this Agreement shall continue unaffected by the fire or other casualty except
that Focal shall be entitled to receive all insurance proceeds which may be
payable to XCOM with respect thereto, and XCOM shall assign to Focal all of
XCOM's rights to any such insurance proceeds.

         12. Default. In the event either party shall breach this Agreement and
fail to cure such breach within fourteen (14) days after receipt of notice from
the nonbreaching party, the nonbreaching party may terminate this Agreement for
default and exercise any remedy available, unless otherwise limited in this
Agreement.

         13. Indemnification. Each party shall defend, indemnify and hold
harmless the other from any and all claims, losses, damages, causes of action,
costs, and expenses of any kind or nature, including attorney fees, incurred by
the other party, to the extent caused by the negligence, willful misconduct or
breach of this Agreement by the other, or by breach of the warranties and
representations of the other.

         14. Brokers. Each party shall bear the cost of any broker or real
estate agent which it may have retained or otherwise consulted with in
connection with the transactions described herein and each party hereby
indemnifies the other against, and agrees to hold the other harmless from, any
liability or claim (and all expenses, including reasonable attorney's fees) for
brokerage commissions or similar fees or compensation arising out of or in any
way connected with any claim by, or dealings with, or agreements between the
indemnifying party and any broker or real estate agent relating to the
transactions described herein.

                                       4
<PAGE>
 
         15. Assignment. This Agreement may not be assigned by either party
without the express written consent of the other party, which consent may be
given or withheld in the sole discretion of such other party.

         16. Force Majeure. If either party, by reason of Force Majeure (as
hereafter defined), is prevented from, or hindered or delayed in, carrying out
its obligations under this Agreement, the obligation of the parties insofar as
they are affected by such Force Majeure shall be postponed during the
continuance of the Force Majeure. "Force Majeure" means any act of God, strike,
riot, civil disturbance, interruption by government or court order, law,
statute, ordinance or regulation promulgated by a government authority having
jurisdiction or any other cause (other than the affected party's fault or
negligence) not reasonably within the control of such party and which such party
could not have prevented and is unable to overcome by exercise of reasonable
care.

         17. Binding Effect. This Agreement shall be binding upon the parties
hereto and their respective permitted successors and assigns.

         18. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts.

         19. Counterparts. This Agreement may be executed in counterparts.

         DATED: December 17, 1998.


                                       XCOM TECHNOLOGIES, INC.


                                       By: /s/ Daniel Caruso
                                          -----------------------------------
                                               Daniel Caruso
                                       Title: Executive Vice President, XCOM

                                       FOCAL COMMUNICATIONS CORPORATION
                                       OF MASSACHUSETTS


                                       By: /s/ John R. Barnicle
                                          -----------------------------------
                                               John R. Barnicle

                                       Title:   Executive Vice President,
                                                Chief Operating Officer

                                       5
<PAGE>
 
                                   Exhibit "A"
                            ASSIGNMENT AND ASSUMPTION

KNOW ALL MEN BY THESE PRESENTS:

         XCOM Technologies, Inc., a subsidiary of Level 3 Communications, Inc.
("Seller"), hereby assigns, transfers, sets over and conveys to FOCAL
Communications Corporation of Massachusetts ("Buyer") all of Seller's right,
title and interest in, under and to that certain Facilities Management Agreement
("Facilities Agreement") entered into between Seller and Com/Energy Services
Company dated June 23, 1997.

         Buyer, in consideration of the execution and delivery of this
instrument, for itself and for its successors and assigns, hereby assumes and
agrees to perform all of the obligations, covenants and agreements required to
be performed by Seller under the Facilities Agreement which accrue from and
after the date of this instrument.

         Seller agrees to indemnify and hold harmless Buyer from any and all
demands, claims, causes of action, damages and liabilities (including reasonable
attorney fees) asserted against or incurred by Buyer as a result of Seller's
failure to observe or perform the obligations and duties of Seller under the
Facilities Agreement prior to the date of this instrument.

         Buyer agrees to indemnify and hold harmless Seller from any and all
demands, claims, causes of action, damages and liabilities (including reasonable
attorney fees) asserted against or incurred by Seller as a result of Buyer's
failure to observe or perform the obligations and duties of Buyer under the
Facilities Agreement from and after the date of this instrument.

         This Assignment and Assumption may be executed in counterparts.

         IN WITNESS WHEREOF, this Assignment and Assumption has been executed
this 6th day of January, 1999.

                                       XCOM TECHNOLOGIES, INC.


                                       By /s/ Kevin O'Hara
                                          -----------------------------------
                                              Kevin O'Hara
                                        Title: President

                                       FOCAL COMMUNICATIONS CORPORATION
                                       OF MASSACHUSETTS


                                       By /s/ Robert C. Taylor, Jr.
                                          -----------------------------------
                                              Robert C. Taylor, Jr.
                                        Title: President
<PAGE>
 
                                   Exhibit "B"
                                  BILL OF SALE

KNOW ALL MEN BY THESE PRESENTS:

         For valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, XCOM TECHNOLOGIES, INC., a subsidiary of Level 3
Communications, Inc. ("Seller"), hereby sells, transfers, conveys and assigns to
FOCAL COMMUNICATIONS CORPORATION OF MASSACHUSETTS ("Buyer"), the equipment and
other personal property described on Exhibit "A" attached hereto (the
"Equipment"):

         Seller covenants and represents to Buyer that Seller: (a) is the lawful
owner of the Equipment and the Equipment is free from all liens and
encumbrances, (b) has legal power and lawful authority to convey the Equipment,
and (c) warrants and will defend title to the Equipment against the claims of
all persons.

         Except as expressly set forth above, Seller makes no representations or
warranties as to the condition, value, utility, use, merchantability, fitness
for a particular purpose or otherwise with respect to the Equipment and the
Equipment is sold, transferred, conveyed and assigned in its "as is" condition.

         IN WITNESS WHEREOF, Seller has executed this Bill of Sale as of the 6th
day of January, 1999.

                                       XCOM TECHNOLOGIES, INC.


                                       By /s/ Kevin O'Hara
                                          -----------------------------------
                                              Kevin O'Hara
                                        Title: President

STATE OF Colorado          )
                           ) ss.
COUNTY OF Boulder          )

         On this 6th day of January, 1999, before me, a notary public in and for
said county and state, personally came Kevin O'Hara, President of XCOM
TECHNOLOGIES, INC., known to me to be the identical person who signed the
foregoing instrument and acknowledged the execution thereof to be his voluntary
act and deed and the voluntary act and deed of said corporation.

         WITNESS my hand and notarial seal at Louisville, in said county and
state, the day and year last above written.

[SEAL]
                                       Kim Bartlett
                                       ---------------------
                                       Notary Public

                                       MY COMMISSION EXPIRES 9/30/2002
<PAGE>
 
                                   Exhibit "A"
                                (to Bill of Sale)
                                    EQUIPMENT

1.       D.C. POWER PLANT

5) Lamarche Rectifiers
Model # A36F- 400 -48-C3
Input 40A / 480V / 4wire ea.
Output -48V dc. / 400A

1) DC Battery Disconnect
CAT # WLDC2610
Capacity 2000A dc.
72)  Decca Batteries

1)  AC Distribution Panel  400A / 480V
 Cat # SEE42ML400ATS

2.       SECURITY SYSTEM

Advantor access control system
- ------------------------------
1) Advantor Access system Software
1) Advantor Access- 4-CA Master
1) Advantor Access- 4A
2) Power Supply Units
10) Keri IP-1003 Proximity Readers
10) Electric Door Strikes
10) Recessed Alarm Switches

Surveillance
- ------------
8) Security Surveillance Color Cameras
1) Dedicated Micros SX9C Color Digital Multiplexer
       1)Sanyo SRT- 672 Time Lapse Video Recorder
1) Color Monitor Alarm
1)Radionics Alarm CPU with multizone and alpha touchpad for backup alarm
interface and havoc capability. Model # D7212


3.       DIGITAL ACCESS CROSS CONNECT SYSTEM (DACCS)

General Description:
- --------------------
  A fully redundant digital system capable of terminating and cross connecting
  digital signals at the DS3 and DS1 levels. In addition, this system has
  optional Sonet (OC-3) capabilities.

Detailed Specifications of System at 1 Main St.:
- ------------------------------------------------
Manufacturer: Tadiran
Model: T::DAX
Type:  3/1 with Sonet OC-3 interface.

                                       2
<PAGE>
 
Layout:  5 bays numbered 3 through 7

Bay Details by bay number:
- --------------------------
Bay #3: Type I (optical shelf bay)
Shelf 1: OC-3 Interface shelf:
         - 1x set OC-3 interface cards

Bay #4: Type II (standard bay)
Shelf 1: NB interface shelf.
Switch Network Shelf: Switching Matrix cards.
Shelf 2: DS3 interface shelf:
         - 8 PAMX DS3 cards.
         - 1 PAMX DS3 protect card.
         - Common cards for protection switching.

Bay #5: Type II (standard bay)
Admin Shelf: - 2 ACP processor cards
         - 1 AIC (craft interface port)
         - Tape drive unit
         - TAU (test access unit w/ 14 ports)
         - Common cards
Shelf 1: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature)
Switch Network Shelf: Switch matrix cards.
Shelf 2: DS3 interface shelf:
 - 8 PAMX DS3 cards.
         - 1 PAMX DS3 card protection.
         - Common cards for protection switching.

Bay #6: Type II (standard bay)
Shelf 1: DS1 interface:
- -  224 LDS T1 cards (w/extended LBO feature)
Shelf 2: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.
- - Common cards for protection switching.
Shelf 3: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.
- - Common cards for protection switching.

Bay #7: Type II (standard bay)
Shelf 2: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature).
Shelf 2: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature).
Shelf 3: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.

                                       3
<PAGE>
 
- - Common cards for protection switching.

4.       RACKS (42), DSX, FUSE PANELS, ETC.

Rack 1 RR01.01 Telect Fuse Panel, 7x23 manufacturer Newton
Rack 2 RR01.02 2-NT D4 Banks with 6 DSU's, - 3 Patch Panels (SS7), - NT fuse
panel (7x23 Newton)
Rack 3 RR01.03 8 DSX shelves (ADC) assigned to the DMS500 DTC's (7x23 Newton)
Rack 4 RR01.04 2 DSX shelves (ADC) assigned to the DMS500 DTC's/DTCI's (7x23
Newton)
Rack 5 RR01.05 9 DSX shelves (ADC) assigned to the DMS500 DTC's/DTCI's (7x23
Newton)
Rack 6 RR01.06 Telcom Solutions GPS Timing Reference, 2 DCD 523's (7x23 Newton)
Rack 7 RR01.07 13 DSX shelves (ADC) assigned to the T::DAX (Tadiran) 7x19
Chatsworth Products Inc> (CPI)
Rack 8 MDF Bay - 7x23 Newton, DSX shelves (ADC) Total of 6.
Rack 9-42 33 bays 7x19 Newton.
RR4.01 thru 4.11 Also have Telect fuse panels (total 11)
10 Locking Server Cabinets 90" for 23" or 19" mounting rails.


5.       DMS500 CONFIGURATION AND INVENTORY

The DMS500 was purchased from Nortel and installed in 7/97. There have been 4
augments made to date.

Configuration/Inventory:

Processor Type:            BRISC 70EM
Software Load:             NSC07
DTC7 Ports:                14,400
DTCi Ports:                12,480
Switch Cabinets:           47


Legend:           DTC7     = SS7 Trunk Port (DS-0)
                  DTCi     = PRI Port (DS-0)

                                       4
<PAGE>
 
                                   Exhibit "C"
                              CO-LOCATION AGREEMENT

         XCOM Technologies, Inc., a subsidiary of Level 3 Communications, Inc.
("XCOM"), and Focal Communications Corporation of Massachusetts ("Focal") hereby
agree as follows:

         1. Principal Agreement. Focal and XCOM are parties to a certain
Purchase Agreement dated December 17, 1998 (the "Principal Agreement"). Terms
capitalized in this Co-location Agreement and not otherwise defined shall have
the meanings ascribed to them in the Principal Agreement. This Co-location
Agreement is being entered into as a condition to, and contemporaneous with, the
Closing under the Principal Agreement.

         2. Premises. Focal has contemporaneously herewith entered into the New
Lease for the Premises.

         3. Co-Location. Focal hereby grants to XCOM the right (collectively the
"Co-location Right"), during the Term (as hereafter defined), to co-locate
XCOM's equipment in the Premises and use the Premises and the Equipment for
communications purposes. The Co-location Right shall include the use of all
utilities serving the Premises, including electrical services, together with all
associated and existing infrastructure relating to the Premises, including a
backup battery system, emergency generator and specialized cooling equipment.
XCOM and Focal agree that their respective uses of the Premises and Equipment
shall conform with the operating procedures set forth on Appendix I attached
hereto and such other policies and procedures as may be mutually agreed to from
time to time. In no event shall any procedures or policies be applied, or any
action taken by Focal, in a manner which discriminates between the customers of
Focal and the customers of XCOM. Focal shall not disturb or interfere with
XCOM's equipment in the Premises. Focal shall not perform any necessary
relocation of XCOM's equipment without the prior approval of XCOM. Such approval
shall be requested by Focal at least five working days in advance of the
relocation and shall not be unreasonably withheld by XCOM.

         4. Usage. In addition to the Co-Location Right, through January 31,
1999: (a) the security system and PBX of XCOM in the Premises may remain and be
utilized by XCOM; and (b) XCOM may use office space in the Premises for up to
ten people, along with related office equipment; (together the "Usage Right").
In the event XCOM has not removed the equipment and personnel associated with
the Usage Right no later than February 7, 1999, XCOM shall pay Focal liquidated
damages of $1000.00 per day commencing on February 8, 1999 and for each day
thereafter until they have been removed.

         5. Equipment Augmentation.

         a. Focal covenants and agrees to augment, at its own cost and expense,
the switch component of the Equipment by adding not less than 4,800 ports
consisting of 2,880 DTCI ports and 1,920 DTC7 ports (the "First Port
Augmentation") on or before February 22, 1999. In the event Focal fails to
complete the First Port Augmentation by February 22, 1999, but thereafter
completes the First Port Augmentation on or before April 22, 1999, XCOM shall be
entitled to a credit (the "Credit") against Monthly Port Charges (as hereafter
defined) equal to the product obtained when (a) $4,869.00, is multiplied by (b)
the number of days between February 22, 1999 and the date the First Port
Augmentation is completed.
<PAGE>
 
         b. In addition to the First Port Augmentation, Focal covenants and
agrees to augment, at its own cost and expense, the switch component of the
Equipment by adding not less than 9,600 ports consisting of 4,800 DTCI ports and
4,800 DTC7 ports (the "Second Port Augmentation") on or before March 5, 1999. In
the event Focal fails to complete the Second Port Augmentation by March 5, 1999,
but thereafter completes the Second Port Augmentation on or before April 10,
1999, XCOM shall be entitled to a Credit against Monthly Port Charges equal to
the product obtained when (a) $4,869.00, is multiplied by (b) the number of days
between March 5, 1999 and the date the Second Port Augmentation is completed.

         6. Monthly Port Charges. Subject to the Credit, in consideration of the
Co-location Right, XCOM shall pay a co-location fee to Focal based upon the
usage of ports by XCOM each month during the Term (the "Monthly Port Charges").
The number of ports used each month by XCOM for purposes of computing the
Monthly Port Charges shall be the number of ports used by XCOM on the first day
of the month. Focal covenants and agrees that at least the following number of
ports shall be available to XCOM during the Term from and after the date
specified (the "Minimum Ports"):

         Date                                     Minimum Ports
         ----                                     -------------
         Effective Date                               26,880
         01/22/99                                     31,680
         03/05/99                                     41,280

The Monthly Port Charges for the Minimum Ports shall be as follows:

         Period                                           Monthly Port Charge
         ------                                           -------------------
         Date hereof through 03/31/99                             ***
         04/01/99 through 09/30/99                                ***
         10/01/99 through 10/31/99                                ***
         11/01/99 through 11/30/99                                ***
         12/01/99 through 12/31/99                                ***
         01/01/00 through 01/31/00                                ***
         02/01/00 through 02/28/00                                ***
         03/01/00 through 03/31/00                                ***
         04/01/00 through 04/30/00                                ***
         05/01/00 through the expiration of the Term              ***

The Monthly Port Charge for any port used by XCOM in excess of the Minimum Ports
shall be *** per port through April 30, 2000, and *** per port thereafter.
The Credit shall be applied to Monthly Port Charges before XCOM shall be
required to pay the same. In the event any portion of the Credit shall remain at
the end of the Term that has not been fully applied against Monthly Port
Charges, such amount shall be paid to XCOM in cash within fifteen days of the
end of the Term.

         7. Term. This Co-location Agreement and the Co-location Right shall be
effective commencing with the date hereof and continuing until the date XCOM
ceases to use the Premises and Equipment under the Co-location Right and gives
written notice thereof to Focal (the "Term"). Upon the expiration of the Term,
Focal agrees to execute (with XCOM) joint written instructions to Escrow Agent
authorizing and directing the payment of the Escrowed Amount then held by Escrow
Agent to XCOM.

- --------------
***Confidential information omitted pursuant to a request for confidential 
treatment filed separately with the Securities and Exchange Commission.

                                       2
<PAGE>
 
         8. Insurance. Each party agrees to maintain at its expense during the
Term: (a) comprehensive general liability insurance in an amount not less than
$2,000,000.00 per occurrence for bodily injury or property damage, (b) workers'
compensation insurance in an amount not less than prescribed by statutory
limits, and (c) fire and extended coverage insurance on all such party's
equipment and personal property in the Premises. Neither party shall be liable
to the other for any loss or damage of such party's equipment or other personal
property located in the Premises and any policy of insurance covering such
equipment and personal property shall provide a waiver of subrogation rights
against the other party.

         9. Indemnification. Each party agrees to indemnify, defend and hold
harmless the other party from any claims, demands, actions, damages,
liabilities, judgments, expenses and costs arising or resulting from such
party's use of the Premises or the Equipment, or the use by any third party
having access to the Premises by virtue of its relationship with such party
(e.g., contractors or customers of such party) or by reason of any breach or
nonperformance of any covenant or obligation herein or the violation of any law
or regulation; provided, and notwithstanding anything contained herein to the
contrary, unless due to the willful misconduct of a party, neither party shall
be liable in any way for consequential or special damages or lost profits or
lost revenues of the other party.

         10. Assignment. Neither this Co-location Agreement nor the Co-location
Right may be assigned by XCOM without the consent of Focal, which consent may be
given or withheld in the sole discretion of Focal; provided, no consent of Focal
shall be required, and XCOM may assign, in whole or in part, this Co-location
Agreement and the Co-location Right to any affiliate of XCOM (for purposes
hereof, the term "affiliate" shall mean any entity which controls, is controlled
by, or is under common control with, XCOM).

         11. Force Majeure. If either party, by reason of Force Majeure (as
hereafter defined), is prevented from, or hindered or delayed in, carrying out
its obligations under this Co-location Agreement, the obligation of the parties
insofar as they are affected by such Force Majeure shall be postponed during the
continuance of the Force Majeure. "Force Majeure" means any act of God, strike,
riot, civil disturbance, interruption by government or court order, law,
statute, ordinance or regulation promulgated by a government authority having
jurisdiction or any other cause (other than the affected party's fault or
negligence) not reasonably within the control of such party and which such party
could not have prevented and is unable to overcome by exercise of reasonable
care.

         12. Counterparts. This Co-location Agreement may be executed in
counterparts.

                                       3
<PAGE>
 
         DATED:  January 6, 1999.

                                       XCOM TECHNOLOGIES, INC.


                                       By /s/ Kevin O'Hara
                                         --------------------------------
                                         Title: President

                                       FOCAL COMMUNICATIONS CORPORATION
                                       OF MASSACHUSETTS


                                       By /s/ Robert C. Taylor, Jr.
                                         --------------------------------
                                         Title: President


                                       4
<PAGE>
 
                                   APPENDIX I

1.   From Closing until Focal Commercial Launch: From Closing until Focal
     activates its first customer the following joint operating procedures will
     be followed:

(a)      Focal will take over responsibility for maintenance of the Premises and
         all Focal-owned equipment within the Premises,  including the switch.
         Focal will submit all plans for construction and switch augmentation
         work to XCOM for approval, which approval will not be unreasonably
         withheld. No currently envisioned work would require any network
         downtime, but Focal agrees to coordinate any such work within a
         prescribed maintenance window, as defined by XCOM, and allowing at
         least five working days notice to XCOM. XCOM will have no more than
         five working days to provide feedback to Focal on all plans Focal
         submits to it. Focal agrees to have its own on-site supervisor(s)
         oversee any work of outside contractors.

(b)      As no Focal customers will be active, XCOM can retain, if it so
         chooses, full access to the Premises. Co-location customers will have
         access to the switch room only with a Focal or XCOM escort. XCOM agrees
         to not allow any new customers to co-locate in the Premises.

(c)      XCOM recognizes that Focal will require similar access during the
         installation of new switching equipment and/or physical construction.
         Focal monitoring of the switch and related facilities is estimated to
         begin upon Closing. Focal agrees to provide surveillance to all
         equipment in the Premises including electronic card key access systems,
         etc. To the extent that additional equipment is required to remotely
         monitor the Premises (such as alarm scan points, etc.), Focal will be
         responsible for providing such equipment.

(d)      Focal will take full control over any switch programming, etc.
         effective upon the Closing. XCOM should continue to take all calls,
         including those reporting troubles, from its customers. XCOM will
         contact Focal to facilitate any work necessary. Focal will also take
         proactive measures to respond to alarms generated by switch and related
         equipment within sixty minutes and will notify the appropriate XCOM
         personnel within sixty minutes. Focal will use best efforts to provide
         translations in the switch within twenty-four hours.

2.   Focal Commercial Launch until Expiration of Term: From the time Focal
     activates its first customer until the expiration of the Term the following
     procedures will be followed:

(a)      XCOM employees and co-location customers will have access to the switch
         room only with a Focal escort. This access will be on a 24 hours per
         day, 7 days per week basis, but a one hour response time will be
         allowed for after hours access. (After hours shall be considered
         anything beyond 8:00 a.m. to 5:00 p.m., Monday through Friday,
         excluding holidays.) XCOM will be responsible for paying the
         appropriate call-out fees, if less than eighteen hours notice is given,
         for such after hour access in conformance with Focal's normal rates for
         such services. XCOM will not pay any fees to Focal for after hour
         access if more than eighteen hours notice is given. The rate for this
         service will be $50 per hour with a four hour minimum.
<PAGE>
 
(b)      Focal expects to have new co-location space completed by the time it
         activates its first customer. To the extent that XCOM or its customers
         require 24 hours per day, 7 days per week unescorted access to their
         equipment, they can do so by relocating their equipment to this
         co-location space.

(c)      Focal will make its technicians available, whether on site or via its
         Network Switching Operations Center, to XCOM to coordinate the moving
         of its customers to XCOM's new equipment. There will be no additional
         charges for such services during normal business hours (8:00 a.m. to
         5:00 p.m., Monday through Friday, excluding holidays) or during after
         hours with five working days notice. The rate for this service will be
         $50 per hour with a four hour minimum.

(d)      Focal and XCOM both anticipate utilizing their own interconnection
         networks to provide services to their own customers. To the extent that
         XCOM makes use of Focal's interconnection network, such as the use of
         LNP, if installed by Focal, to facilitate the transition of its
         customers to its new switching equipment, XCOM agrees to bear
         commensurate costs of such services. XCOM will not be responsible for
         any LNP charges associated with customers that are explicitly
         transitioned by XCOM to Focal. It is estimated that the costs
         associated with this service will be a one time charge of $10,000 plus
         the then current rate for a per call charge based on the Bell Atlantic
         LNP query fee plus a twenty percent mark up.

(e)      Focal will initiate trouble ticket procedures on any switch-affecting
         situation and will notify XCOM of the problem and corrective actions
         being taken within sixty minutes.

(f)      To the extent that issues arise that cannot be resolved on site, the
         following escalation procedures should be used:
<TABLE> 
<CAPTION> 
                           Focal
                           -----
         <S>               <C> 
         Construction      Jeff Wells - Director of Operation  312/895-8404
         Switch            Kim Morgan - Director of Switching Control Center  312/895-8337
         Escalation        John Barnicle - Chief Operating Officer  312/895-8237

                           XCOM
                           ----
         Construction      Brian Corcoran - Construction Manager  617/500-0123
         Switch            Mark Whitney      - Boston City Operations Director  617/500-0107
         Escalation        Frank Mambuca - VP Eastern Operations  917/305-2323
                           Andrea Gavalas - Director Interconnection Services  303/635-9617
</TABLE> 
                                       2
<PAGE>
 
                                   Exhibit "D"
                                    EQUIPMENT

1.       D.C. POWER PLANT

5) Lamarche Rectifiers
Model # A36F- 400 -48-C3
Input 40A / 480V / 4wire ea.
Output -48V dc. / 400A

1) DC Battery Disconnect
CAT # WLDC2610
Capacity 2000A dc.
72)  Decca Batteries

1) AC Distribution Panel  400A / 480V
Cat # SEE42ML400ATS

2.       SECURITY SYSTEM

Advantor access control system
- ------------------------------
1) Advantor Access system Software
1) Advantor Access- 4-CA Master
1) Advantor Access- 4A
2) Power Supply Units
10) Keri IP-1003 Proximity Readers
10) Electric Door Strikes
10) Recessed Alarm Switches

Surveillance
- ------------
8) Security Surveillance Color Cameras
1) Dedicated Micros SX9C Color Digital Multiplexer
       1)Sanyo SRT- 672 Time Lapse Video Recorder
1) Color Monitor Alarm
1)Radionics Alarm CPU with multizone and alpha touchpad for backup alarm
interface and havoc capability. Model # D7212


3.       DIGITAL ACCESS CROSS CONNECT SYSTEM (DACCS)

General Description:
- --------------------
A fully redundant digital system capable of terminating and cross connecting
digital signals at the DS3 and DS1 levels. In addition, this system has optional
Sonet (OC-3) capabilities.

Detailed Specifications of System at 1 Main St.:
- ------------------------------------------------
Manufacturer: Tadiran
Model: T::DAX
Type:  3/1 with Sonet OC-3 interface.
Layout:  5 bays numbered 3 through 7
<PAGE>
 
Bay Details by bay number:
- --------------------------
Bay #3: Type I (optical shelf bay)
Shelf 1: OC-3 Interface shelf:
         - 1x set OC-3 interface cards

Bay #4: Type II (standard bay)
Shelf 1: NB interface shelf.
Switch Network Shelf: Switching Matrix cards.
Shelf 2: DS3 interface shelf:
         - 8 PAMX DS3 cards.
         - 1 PAMX DS3 protect card.
         - Common cards for protection switching.

Bay #5: Type II (standard bay)
Admin Shelf: - 2 ACP processor cards
         - 1 AIC (craft interface port)
         - Tape drive unit
         - TAU (test access unit w/ 14 ports)
         - Common cards
Shelf 1: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature)
Switch Network Shelf: Switch matrix cards.
Shelf 2: DS3 interface shelf:
 - 8 PAMX DS3 cards.
         - 1 PAMX DS3 card protection.
         - Common cards for protection switching.

Bay #6: Type II (standard bay)
Shelf 1: DS1 interface:
- -  224 LDS T1 cards (w/extended LBO feature)
Shelf 2: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.
- - Common cards for protection switching.
Shelf 3: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.
- - Common cards for protection switching.

Bay #7: Type II (standard bay)
Shelf 2: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature).
Shelf 2: DS1 interface:
- - 224 LDS T1 cards (w/extended LBO feature).
Shelf 3: DS3 interface shelf:
- - 8 PAMX DS3 cards.
- - 1 PAMX DS3 card protection.
- - Common cards for protection switching.

                                       2
<PAGE>
 
4.       RACKS (42), DSX, FUSE PANELS, ETC.

Rack 1 RR01.01 Telect Fuse Panel, 7x23 manufacturer Newton
Rack 2 RR01.02 2-NT D4 Banks with 6 DSU's, - 3 Patch Panels (SS7), - NT fuse
panel (7x23 Newton)
Rack 3 RR01.03 8 DSX shelves (ADC) assigned to the DMS500 DTC's (7x23 Newton)
Rack 4 RR01.04 2 DSX shelves (ADC) assigned to the DMS500 DTC's/DTCI's (7x23
Newton)
Rack 5 RR01.05 9 DSX shelves (ADC) assigned to the DMS500 DTC's/DTCI's (7x23
Newton)
Rack 6 RR01.06 Telcom Solutions GPS Timing Reference, 2 DCD 523's (7x23 Newton)
Rack 7 RR01.07 13 DSX shelves (ADC) assigned to the T::DAX (Tadiran) 7x19
Chatsworth Products Inc> (CPI)
Rack 8 MDF Bay - 7x23 Newton, DSX shelves (ADC) Total of 6.
Rack 9-42 33 bays 7x19 Newton.
RR4.01 thru 4.11 Also have Telect fuse panels (total 11)
10 Locking Server Cabinets 90" for 23" or 19" mounting rails.


5.       DMS500 CONFIGURATION AND INVENTORY

The DMS500 was purchased from Nortel and installed in 7/97. There have been 4
augments made to date.

Configuration/Inventory:

Processor Type:            BRISC 70EM
Software Load:             NSC07
DTC7 Ports:                14,400
DTCi Ports:                12,480
Switch Cabinets:           47


Legend:           DTC7     = SS7 Trunk Port (DS-0)
                  DTCi     = PRI Port (DS-0)


                                       3
<PAGE>
 
                                  Exhibit "E"
                                ESCROW AGREEMENT

          XCOM Technologies, Inc., a subsidiary of Level 3 Communications, Inc.
("XCOM"), Focal Communications Corporation of Massachusetts ("Focal") and
Norwest Bank Colorado, National Association ("Escrow Agreement") hereby agree as
follows:

          1. Principal Agreement. Focal and XCOM are parties to a certain
Purchase Agreement dated December 17, 1998 (the "Principal Agreement"). Terms
capitalized in this Agreement and not otherwise defined shall have the meanings
ascribed to them in the Principal Agreement. This Agreement is being entered
into as a condition to, and contemporaneous with, the Closing under the
Principal Agreement.

          2. Appointment of Escrow Agent. Escrow Agent is hereby appointed to
act as escrow agent hereunder and Escrow Agent hereby agrees to act as escrow
agent hereunder.

          3. Escrow Funds. In accordance with paragraph 6 of the Principal
Agreement, Focal hereby delivers to Escrow Agent in immediately available funds
the sum of $2,500,000.00 (the "Escrowed Amount"). Escrow Agent hereby accepts
the Escrowed Amount for deposit in escrow pursuant to the provisions of this
Agreement. Escrow Agent shall establish a segregated account for the Escrowed
Amount and the securities in which the Escrowed Amount may from time to time be
invested in accordance with this Agreement (the "Escrow Fund").

          4. Investments. Escrow Agent shall invest and reinvest the Escrow Fund
at the written direction of XCOM only in: (a) short term direct obligations of,
or obligations fully guaranteed by, the United States of America or any agency
thereof, and (b) certificates of deposit issued by any bank or national banking
association (including Escrow Agent) having total capital and surplus in excess
of $100,000,000.00 and which is fully insured by the Federal Deposit Insurance
Corporation (collectively called the "Permitted Securities"). Interest and other
earnings on the Permitted Securities shall be added to the Escrow Fund, or at
the option of XCOM, paid to XCOM. Any loss incurred from an investment shall be
borne by the Escrow Fund. Investment and reinvestment of the Escrow Fund shall
be made only in Permitted Securities. Whenever Escrow Agent shall be required to
make any payment under this Agreement, Escrow Agent shall, if the cash held by
it hereunder is insufficient for such purpose, liquidate such of the Permitted
Securities held hereunder as XCOM shall timely select by written notice to
Escrow Agent or, if XCOM shall, in the judgment of Escrow Agent, fail to make
such timely selection, in the order of maturity, in order to make such payment.
Escrow Agent shall deliver monthly reports to XCOM and Focal as to the status of
the Escrow Fund and the earnings thereon.

          5. Right to Escrow Fund. The Escrow Fund shall be for the exclusive
benefit of XCOM and, to the extent set forth herein, Focal, and their respective
successors and assigns, and no other person or entity shall have any right,
title or interest therein. Any claim of any person to the Escrow Fund, or a part
thereof, shall be subject and subordinate to the prior rights thereto of XCOM
and Focal.

          6. Distributions from Escrow Fund. Escrow Agent shall continue to hold
Escrow Fund in its possession until authorized hereunder to distribute Escrow
Fund, or any specified portion thereof, as follows: (a) upon the joint written
instructions of XCOM and Focal; or (b) as determined by the final order, decree
or judgment of a court of competent jurisdiction in the
<PAGE>
 
United States of America (the time for appeal having expired with no appeal
being taken) in a proceeding to which XCOM and Focal are parties.

          7. Duties of Escrow Agent. The obligations of Escrow Agent are those
specifically provided in this Agreement and no other, and Escrow Agent shall
have no liability under, or duty to inquire into the terms and provisions of,
any other agreement between the parties hereto. The duties of Escrow Agent are
purely ministerial in nature, and Escrow Agent shall not incur any liability
whatsoever except for its own gross negligence or willful misconduct. Escrow
Agent may consult with counsel of its own choice, and shall not be liable for
following the advice of such counsel. Escrow Agent shall not have any
responsibility for the genuineness or validity of any document or other item
deposited with it or of any signature thereon and shall not have any liability
for acting in accordance with any written instructions or certificates given to
it as specified herein. Escrow Agent may resign and be discharged from its
duties hereunder at any time by giving at least thirty days' prior written
notice of such resignation to XCOM and Focal, specifying a date upon which such
resignation shall take effect; provided however, Escrow Agent shall continue to
serve until its successor accepts the Escrow Fund. Upon receipt of such notice
from Escrow Agent, a successor escrow agent shall be appointed by XCOM and
Focal, such successor escrow agent to become the Escrow Agent hereunder on the
resignation date specified in such notice. If an instrument of acceptance by the
successor escrow agent shall not have been delivered to the resigning Escrow
Agent within forty days after the giving of such notice of resignation, the
resigning Escrow Agent may petition any court of competent jurisdiction for the
appointment of a successor escrow agent. XCOM and Focal may at any time, by
mutual agreement, substitute a new escrow agent by giving ten days' notice
thereof to the current Escrow Agent and paying all fees and expenses of the
current Escrow Agent.

          8. Indemnification and Fees of Escrow Agent. XCOM and Focal shall
jointly and severally hold Escrow Agent harmless and indemnify Escrow Agent
against any loss, liability, expense (including attorney fees and expenses),
claim or demand arising out of, or in connection with, the performance of Escrow
Agent's obligations in accordance with the provisions of this Escrow Agreement,
except for any of the foregoing arising out of the gross negligence or willful
misconduct of Escrow Agent. Any fees of Escrow Agent shall be deducted from the
Escrow Fund.

          9. Disputes. If any disputes should arise with respect to the payment
and/or ownership or right of possession of the Escrow Fund, Escrow Agent is
authorized and directed to retain in its possession, without liability to
anyone, all or any part of the Escrow Fund until such time as the dispute shall
have been settled either by mutual agreement by the parties concerned or by the
final order, decree or judgment of a court of competent jurisdiction in the
United States of America (the time for appeal having expired with no appeal
having been taken) in a proceeding to which XCOM and Focal are parties, but
Escrow Agent shall be under no duty whatsoever to institute or defend any such
proceedings.

          10. Notices. All notices or other communications which are required or
permitted herein shall be in writing and sufficient if delivered personally,
sent by prepaid air courier, or sent by registered or certified mail, postage
prepaid, return receipt requested, addressed as follows:



                   If to XCOM:         Attn: Thomas C. Stortz
                                       XCOM Technologies, Inc.
                                       1450 Infinite Drive
                                       Louisville, CO 80027
<PAGE>
 
                  If to Focal:
                                       ---------------------------
                                       ---------------------------
                                       ---------------------------

                  If to Escrow Agent:  Norwest Bank Colorado, N.A.
                                       1740 Broadway
                                       Denver, CO 80274-8693
                                       Attn:  Leigh M. Lutz

or at such other address as the party to whom notice is to be given may have
furnished to the other party in writing in accordance herewith. Any such
communication shall be deemed to have been given when delivered if delivered
personally, on the business day after dispatch if sent by air courier, or on the
fifth business day after posting if sent by mail.

         11. Governing Law. This Escrow Agreement shall be governed by and
construed in accordance with the laws of the State of Colorado.

         12. Modification. This Escrow Agreement shall not be altered or
otherwise amended except pursuant to an instrument in writing signed by all of
the parties hereto.

         13. Binding Effect. This Escrow Agreement shall be binding upon and
inure to the benefit of the parties hereto and their successors and assigns.

         14. Counterparts. This Escrow Agreement may be executed in
counterparts.

DATED:   January 6, 1999.
                                       XCOM TECHNOLOGIES, INC.

                                       By /s/ Kevin O'Hara
                                         --------------------------------
                                         Title: President

                                       FOCAL COMMUNICATIONS CORPORATION
                                       OF MASSACHUSETTS

                                       By:  Robert Taylor
                                          -------------------------------
                                       Title: President

                                       NORWEST BANKCOLORADO, NATIONAL
                                       ASSOCIATION

                                       By Leigh M. Lutz
                                         --------------------------------
                                       Title: Vice President
<PAGE>
 
                       Assignment and Assumption agreement

         This Assignment and Assumption Agreement ("Assignment Agreement") is
entered into by and between XCOM Technologies, Inc. ("XCOM"), a subsidiary of
Level 3 Communications, Inc., Focal Communications Corporation of Massachusetts
("Focal") and Northern Telecom, Inc. ("Nortel"), as of the 6th day of January,
1999.

                                    RECITALS

         Whereas, Nortel and XCOM are parties to a certain Network Products
Purchase Agreement no X\DM\3-97, and related Product Attachment and Services
Agreement (collectively referred to hereafter as the "Nortel Agreements") in
connection with certain equipment purchased by XCOM from Nortel;

         WHEREAS, Focal and XCOM have executed a certain purchase agreement,
dated January 6, 1999 (the "Purchase Agreement"), pursuant to which, upon the
Closing (as defined in the Purchase Agreement), XCOM will sell to Focal and
Focal will purchase from XCOM certain of the equipment (the "Nortel Equipment")
purchased by XCOM from Nortel pursuant to the Nortel Agreements, as more
specifically identified in Exhibit "A" attached and incorporated herein by this
reference;

         WHEREAS, the Nortel Agreements include a certain Software License (the
"Software License") associated with the Nortel Equipment, a copy of which is
attached hereto as Exhibit "B" and incorporated herein by this reference; and

         WHEREAS, XCOM and Focal have requested that Nortel consent to the
assignment by XCOM, and assumption by Focal, of the Software License.

         NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency which is hereby acknowledged:

         1. XCOM hereby assigns, transfers, sets over and conveys to Focal all
of XCOM's right, title and interest in, under and to, the Software License.

         2. Focal, in consideration of the execution and delivery of this
instrument, for itself and for its successors and assigns, hereby assumes and
agrees to perform all of the obligations, covenants and agreements required to
be performed by XCOM under the Software License which accrue from and after the
date of this instrument.

         3. XCOM agrees to indemnify and hold harmless Focal from any and all
demands, claims, cause of action, damages and liabilities (including reasonable
attorney fees) asserted against or incurred by Focal as a result of XCOM's
failure to observe or perform the obligations and duties of XCOM under the
Software License prior to the date of this instrument.
<PAGE>
 
         4. Focal agrees to indemnify and hold harmless XCOM from any and all
demands, claims, cause of action, damages and liabilities (including reasonable
attorney fees) asserted against or incurred by XCOM as a result of Focal's
failure to observe or perform the obligations and duties of Focal under the
Software License from and after the date of this instrument.

         5. Nortel hereby acknowledges and consents to an assignment of the
Software License to Focal and an assumption of the Software License by Focal and
agrees that from and after the Closing, XCOM shall be released from all
liability under the Software License.



         DATED:  Jan. 6, 1999
               -----------------

                                  XCOM Technologies, INC.


                                  By  /s/ Kevin O'Hara (signature on file)
                                    ------------------------------------------
                                    Title President

                                  FOCAL COMMUNICATIONS CORPORATION
                                  OF MASSACHUSETTS

                                  By /s/ Joseph A Beatty (signature on file)
                                    ------------------------------------------
                                    Title Executive VP

                                  NORTHERN TELECOM, INC.

                                  By /s/ Kathryn D. Musser (signature on file)
                                    ------------------------------------------
                                    Title Senior Manager, Contracts
<PAGE>
 
                                    EXHIBIT A



DMS500 CONFIGURATION AND INVENTORY

The DMS500 was purchased from Nortel and installed in 7/97. There have been 4
augments made to date.

Configuration/Inventory:

Processor Type:            BRISC 70EM
Software Load:             NSC07
DTC7 Ports:                14,400
DTCi Ports                 12,480
Switch Cabinets            47


Legend:           DTC7 = SS7 Trunk Port (DS-0)
                  DTCi = PRI Port (DS-0)





Saved under:  legaltemp$'Chicago4'(G:)   File Name:  Exhibit AB   Typed from a
FAX  received 1/4/99 at 10:56 AM from 402-341- 6000, Fraser & Stryker
<PAGE>
 
                                                       Agreement No. V/DM/2-97
                                                                        Page 1

                                    EXHIBIT B
                                    ---------

                                SOFTWARE LICENSE
                                ----------------

1.       Buyer acknowledges that the Software may contain programs which have
         been supplied by, and are proprietary to, Third Party Software Vendors.
         In addition to the terms and conditions herein, Buyer shall abide by
         any additional terms and conditions provided by Nortel to Buyer with
         respect to any Software provided by any Third Party Software Vendor.

2.       Upon Buyer's payment to Nortel of the applicable fees with respect to
         any Software furnished to Buyer pursuant to this Agreement, Buyer shall
         be granted a personal, non-exclusive, paid-up license to use the
         version of the Software furnished to Buyer only in conjunction with
         Buyer's use of the Equipment with respect to which such Software was
         furnished for the life of that equipment as it may be repaired or
         modified. Buyer shall be granted no title or ownership rights to the
         Software, which rights shall remain in Nortel or its suppliers.

3.       As a condition precedent to this license and to the supply of Software
         by Nortel pursuant to the Agreement, Nortel requires Buyer to give
         proper assurances to Nortel for the protection of the Software.
         Accordingly, all Software supplied by Nortel under or in implementation
         of the Agreement shall be treated by Buyer as the exclusive property,
         and as proprietary and a TRADE SECRET, of Nortel and / or its
         suppliers, as appropriate, and Buyer shall:  a) hold the Software,
         including, without limitation, any methods or concepts utilized therein
         in confidence for the benefit of Nortel and / or its suppliers, as
         appropriate; b) not provide or make the Software available to any
         person except to its employees on a `need to know' basis; c) not
         reproduce, copy, or modify the Software in whole or in part except as
         authorized by Nortel; d) not attempt to decompile, reverse engineer,
         disassemble, reverse translate, or in any other manner decode the
         Software; e) issue adequate instructions to all persons, and take all
         actions reasonably necessary to satisfy Buyer's obligations under this
         license; and f) forthwith return to Nortel, or with Nortel's consent
         destroy, any magnetic tape, disc, semiconductor device or other memory
         device or system and / or documentation or other material, including,
         but not limited to all printed material furnished by Nortel to Buyer
         which shall be replaced, modified or updated.

4.       The obligations of Buyer hereunder shall not extend to any information
         or data relating to the Software which is now available to the general
         public or becomes available by reason of acts or failures to act not
         attributable to Buyer.
<PAGE>
 
                                                       Agreement No. V/DM/2-97
                                                                        Page 2


5.       Buyer shall not assign this license or sublicense any rights herein
         granted to any other party without Nortel's prior written consent.

6.       Buyer shall indemnify and hold Nortel and its suppliers, as
         appropriate, harmless from any loss or damage resulting from a breach
         of this Exhibit B. The obligations of Buyer under this Exhibit B shall
         survive the termination of the Agreement and shall continue if the
         Software is removed from service.

<PAGE>
 
                                                                  Exhibit 10.9


                            FIFTH AMENDMENT TO LEASE
                            ------------------------


         THIS FIFTH AMENDMENT TO LEASE (this "Amendment") is made and entered
into as of this 14th day of October, 1998 by and between TIAA REALTY, INC., a
Delaware corporation, successor-in-interest to Teachers Insurance and Annuity
Association of America, ("Landlord") and FOCAL COMMUNICATIONS CORPORATION OF
ILLINOIS (formerly known as Focal Communications Corporation), a Delaware
corporation, ("Tenant").


                               W I T N E S S E T H
                               -------------------

         WHEREAS, Landlord's predecessor-in-interest and Tenant have heretofore
entered into that certain lease dated as of December 31, 1996 (the "Original
Lease"), pursuant to which Landlord leased to Tenant 10,236 rentable square feet
located on the lower level (the "Original Space") of the building commonly known
as 200 North LaSalle Street, Chicago, Illinois (the "Building");

         WHEREAS, Landlord's predecessor-in-interest and Tenant have heretofore
entered into that certain First Amendment to Lease dated May 14, 1997 (the
"First Amendment") to evidence Tenant's expansion into the additional space of
6,202 rentable square feet on the eighth (8th) floor of the Building (the
"Additional Space"), as more particularly set forth in the First Amendment;

         WHEREAS, Landlord's predecessor-in-interest and Tenant entered into
that certain Second Amendment to Lease dated November 15, 1997 (the "Second
Amendment") to evidence Tenant's expansion into the additional space of 4,153
rentable square feet on the eighth (8th) floor of the Building (the "Eighth
Floor Second Additional Space"), collectively (such Additional Space and the
Second Additional Space referred to herein as the "Eighth Floor Space"), as more
particularly set forth in the Second Amendment;

         WHEREAS, Landlord's predecessor-in-interest and Tenant entered into
that certain Third Amendment to Agreement of Lease dated March 2, 1998 (the
"Third Amendment") to evidence Tenant's installation of a communication device,
as more particularly set forth in the Third Amendment;

         WHEREAS, Landlord's predecessor-in-interest and Tenant entered into
that certain Fourth Amendment to Lease dated April 24, 1998 (the "Fourth
Amendment") to extend the term of the Lease with respect to the Eighth Floor
Space and to evidence Tenant's expansion into the additional space of 11,956
rentable square feet on the Seventh (7th) Floor of the Building (the "Seventh
Floor Space"), as more particularly set forth in the Fourth Amendment (such
Original Lease as amended by the First Amendment, the Second Amendment, the
Third Amendment and the Fourth Amendment and as modified or amended from time to
time, hereafter is called the "Lease");
<PAGE>
 
         WHEREAS, Landlord's predecessor-in-interest and Tenant desire to amend
the Lease according to the terms hereof in order to document the leasing of
additional space on the Seventh Floor. This Amendment does not modify the terms
of the Lease with respect to the Original Space, the Seventh Floor Space or the
Eighth Floor Space;

         NOW THEREFORE, for and in consideration of the covenants and agreements
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant
hereby mutually agree as follows:

         1. Recitals. The foregoing recitals are true and correct and are
incorporated herein by reference.

         2. Controlling Language. Insofar as the specific terms and provisions
of this Amendment purport to amend or modify or are in conflict with the
specific terms, provisions and exhibits of the Lease, the terms and provisions
of this Amendment shall govern and control; in all other respects, the terms,
provisions and exhibits of the Lease shall remain unmodified in full force and
effect.

         3. Seventh Floor Additional Space/Term. Landlord and Tenant hereby
agree that beginning on the earlier of December 1, 1998 or the date upon which
Tenant commences business operations at the demised premises (the "Seventh Floor
Additional Space Commencement Date"), Landlord shall lease to Tenant
approximately 4,593 rentable square feet of space on the seventh (7th) floor of
the Building as more particularly described on Exhibit A attached hereto (the
"Seventh Floor Additional Space") for the remaining portion of the Seventh Floor
Space Term (as defined in the Fourth Amendment). The Seventh Floor Additional
Space shall be subject to all the terms and conditions of the Lease except to
the extent expressly modified or excluded hereby or herein and shall be included
in the "Premises" as the term is used in the Lease. Landlord and Tenant hereby
acknowledge that notwithstanding anything to the contrary set forth in the
Lease, the Seventh Floor Space Term and the Eighth Floor Space Term will each
end on June 30, 2003, such date being the Seventh Floor Termination Date and the
Eighth Floor Termination Date for all purposes in the Lease.

         4. Seventh Floor Additional Space Rent. Effective as of the Seventh
Floor Additional Space Commencement Date and for the duration of the Seventh
Floor Additional Space Term, in addition to (and not in substitution for) the
Rent payable with respect to the Original Space and the Eighth Floor Space and
the Seventh Floor Space under the Lease, Tenant shall pay to Landlord Rent with
respect to the Seventh Floor Additional Space as follows:







                                       2
<PAGE>
 
         A. Base Rent. Base Rent to be paid in monthly installments in advance
on or before the first day of each month of the Term of this Lease set forth in
the following schedule:

Period                            Annual Base Rent             Monthly Base Rent
- --------------------------------------------------------------------------------
Seventh Floor Additional Space    $60,857.25* ($13.25 x 4,593
Commencement Date                 rentable square feet)             $5,071.44
through 6/30/99
- --------------------------------------------------------------------------------
7/1/99 through 6/30/00            $63,153.75 ($13.75 x 4,593
                                  rentable square feet)             $5,262.81
- --------------------------------------------------------------------------------
7/1/00 through 6/30/01            $65,450.25 ($14.25 x 4,593
                                  rentable square feet)             $5,454,19
- --------------------------------------------------------------------------------
7/1/01 through 6/30/02            $67,746.75 ($14.75 x 4,593
                                  rentable square feet)             $5,645.56
- --------------------------------------------------------------------------------
7/1/02 through 6/30/03            $70,043.25 ($15.25 x 4,593
                                  rentable square feet)             $5,836.94
- --------------------------------------------------------------------------------

*the parties acknowledge that this is an annualized amount and that tenant will
not be obligated to pay the entire amount, but rather will be responsible for
making monthly payments for the period indicated.


         B.       Operating Cost Share Rent. Operating Cost Share Rent in an
                  amount equal to the Tenant's Proportionate Share of the
                  Operating Costs for the applicable Fiscal Year of the Lease,
                  paid monthly in advance in an estimated amount.

         C.       Tax Share Rent. Tax Share Rent in an amount equal to the
                  Tenant's Proportionate Share of Taxes for the applicable
                  Fiscal Year of this Lease, paid monthly in advance in an
                  estimated amount.

The method of billing and payment of Operating Cost Share Rent and Tax Share
Rent are set forth in Section 5 of this Amendment.

         Any provision of the Lease or this Amendment to the contrary
notwithstanding, the abatement of Rent payable with respect to the Original
Space pursuant to the Schedule of the Lease shall not apply to the payment of
Rent with respect to the Seventh Floor Additional Space, and such Rent, with
respect to the Seventh Floor Additional Space, shall accrue and Tenant shall be
liable for payment thereof without regard to such abatement provision.

                                       3
<PAGE>
 
         5. Payment of Operating Cost Share Rent and Tax Share Rent. During the
Seventh Floor Additional Space Term, Tenant shall pay Operating Expenses Share
Rent and Tax Share Rent for the Seventh Floor Additional Space in the manner set
forth below.

                  A.       Payment of Estimated Operating Cost Share Rent and
                           Tax Share Rent. Landlord shall reasonably estimate
                           the Operating Costs and Taxes of the Project each
                           Fiscal Year, generally after the beginning of the
                           year. Landlord may revise these estimates, but no
                           more often than twice during any Fiscal Year,
                           whenever it obtains more accurate information, such
                           as the final real estate tax assessment or tax rate
                           for the Project.

                           Within ten (10) days after notice from Landlord
                           setting forth an estimate of Operating Costs for a
                           particular Fiscal Year, Tenant shall pay Landlord an
                           amount equal to one-twelfth (1/12th) of Tenant's
                           Proportionate Share of such estimated Operating Costs
                           for such Fiscal Year, multiplied by the number of
                           months that have elapsed in the applicable Fiscal
                           Year to the date of such payment including the
                           current month, minus payments previously made by
                           Tenant for the months elapsed during the Term.
                           Thereafter on the first day of each month, Tenant
                           shall pay monthly until a new estimate of Operating
                           Costs is applicable, one-twelfth (1/12th) of Tenant's
                           Proportionate Share of the estimated Operating Costs.

                           Within ten (10) days after notice from Landlord
                           setting forth an estimate of Taxes for a particular
                           Fiscal Year, Tenant shall pay Landlord an amount
                           equal to one-twelfth (1/12th) of Tenant's
                           Proportionate Share of such estimated Taxes,
                           multiplied by the number of months that have elapsed
                           during the Term in the applicable Fiscal Year to the
                           date of such payment, including the current month,
                           minus payments previously made by Tenant for the
                           months elapsed. Thereafter on the first day of each
                           month, Tenant shall pay monthly until a new estimate
                           of Taxes is applicable, one-twelfth (1/12th) of
                           Tenant's Proportionate Share of the estimated Taxes.
                           In no event shall anything contained in this Lease be
                           construed to allow Landlord to be reimbursed for
                           greater than one-hundred percent (100%) of the actual
                           Taxes or Operating Costs.


                  B.       Correction of Operating Cost Share Rent. As soon as
                           reasonably possible after the end of each Fiscal
                           Year, Landlord shall deliver to Tenant a report for
                           such year (the "Operating Cost Report") setting forth
                           (a) the actual Operating Costs incurred, (b) the
                           amount of Operating Cost Share Rent due from Tenant,
                           and (c) the amount of Operating Cost Share Rent paid
                           by Tenant. Within twenty (20) days after such
                           delivery, Tenant shall pay to Landlord the amount due
                           minus the amount paid. If the amount paid exceeds the
                           amount due, Landlord shall apply the excess to
                           Tenant's next month's payment of Operating Cost Share
                           Rent, refunding any

                                       4
<PAGE>
 
                           overage directly to Tenant within a reasonable period
                           of time after the determination of such overage.

                  C.       Correction of Tax Share Rent. As soon as reasonably
                           possible after the end of each Fiscal Year, Landlord
                           shall deliver to Tenant a report for such Fiscal Year
                           (the "Tax Report") setting forth (a) the actual
                           Taxes, (b) the amount of Tax Share Rent due from
                           Tenant, and (c) the amount of Tax Share Rent paid by
                           Tenant. Within twenty (20) days after such delivery,
                           Tenant shall pay to Landlord the amount due from
                           Tenant minus the amount paid by Tenant. If the amount
                           paid exceeds the amount due, Landlord shall apply the
                           excess as a credit against Tenant's next month's
                           payment of Tax Share Rent, refunding any overage
                           directly to Tenant within a reasonable period of time
                           after the determination of such overage.

         The definition of Taxes and Operating Costs shall be as set forth in
Section 2C of the Original Lease.

         "Tenant's Proportionate Share," with respect to the Seventh Floor
Additional Space, for calculating the Operating Cost Share Rent and Tax Share
Rent is 0.7376% (based upon 4,593 rentable square feet in the Seventh Floor
Additional Space and 622,667 rentable square feet in the Building).

         6. Condition of the Seventh Floor Additional Space. Landlord is leasing
the Seventh Floor Additional Space to Tenant on the Seventh Floor Additional
Space Commencement Date "AS IS", without any representations or warranties of
any kind (including, without limitation, any express or implied warranties of
merchantability, fitness or habitability) and without any obligation on the part
of Landlord to alter, remodel, improve, repair, or decorate the Premises or any
part thereof.

         7. Tenant's Seventh Floor Additional Space Improvements. Tenant shall
improve the Seventh Floor Additional Space, at its own cost and expenses except
as provided herein, in accordance with plans and specifications approved in
advance by Landlord (such improvements are referred to herein as the "Tenant's
Seventh Floor Additional Space Improvements"). Tenant hereby agrees that the
plans and specifications for the Tenant's Seventh Floor Additional Space
Improvements shall comply with all applicable statutes, ordinances, regulations,
laws and codes. Landlord's approval of any of such plans and specifications (or
any modifications or changes thereto) shall not impose upon Landlord or its
agents or representatives any obligation with respect to the design of the
Tenant's Seventh Floor Additional Space Improvements or with respect to the
compliance of such Tenant's Seventh Floor Additional Space Improvements and/or
the plans and specifications therefor with applicable laws, codes, ordinances
and regulations, it being expressly understood that the obligation with respect
to the design of the Tenant's Seventh Floor Additional Space Improvements and
its compliance with applicable laws, codes, ordinances and regulations rests
with the Tenant and the party responsible for preparing such plans and
specifications.

                                       5
<PAGE>
 
         Tenant's Seventh Floor Additional Space Improvements shall be performed
in accordance with Sections 5(A)(1)-(5), 5(B), 5(C), and 5(D) of the Lease. All
Tenant's Seventh Floor Additional Space Improvements shall be constructed in a
good and workmanlike manner, and only good grades of material shall be used. All
Tenant's Seventh Floor Additional Space Improvements shall be performed in such
a fashion and by such means as necessary to maintain a professional work
environment in the areas surrounding the space to be improved. Tenant shall only
use labor that will work in peace and harmony with other contractors and workers
serving the Building in constructing Tenant's Seventh Floor Additional Space
Improvements. Tenant shall use reasonable efforts to avoid actions which may
unreasonably interfere with or delay the activities of other contractors serving
the Building and other tenants. Tenant shall permit Landlord to observe and
monitor all Tenant's Seventh Floor Additional Space Improvements.

         If Tenant completes the Seventh Floor Additional Space Improvements
within six (6) months of the Seventh Floor Additional Space Commencement Date,
then Landlord hereby agrees to provide Tenant an amount not to exceed
seventy-eight thousand eighty-one dollars ($78,081.00) ($17.00 per rentable
square foot x 4,593 rentable square feet) (the "Improvement Allowance") to be
applied to the cost of the Seventh Floor Additional Space Improvements. Landlord
shall deliver the Improvement Allowance, in whole or in part, to Tenant upon
Landlord's receipt of paid invoices for such Seventh Floor Additional Space
Improvements. Any costs incurred by Tenant with respect to the Seventh Floor
Additional Space Improvements in excess of the Improvement Allowance shall be
paid by Tenant. If Tenant is entitled to receive the Improvement Allowance and
the total cost incurred by Tenant in connection with the Seventh Floor
Additional Space Improvements is less than the Improvement Allowance (the
difference being the "Excess Allowance"), then Landlord hereby agrees that, at
Landlord's option, an amount not in excess of Six Thousand, Eight Hundred and
Eighty-Nine and 50/100 Dollars ($6,889.50) ($1.50 x 4,593 rentable square feet)
of such Excess Allowance may be used as a credit against the first installments
of Base Rent falling due after the Seventh Floor Additional Space Commencement
Date or may be paid in cash by Landlord to Tenant, or both.

         8. Brokerage Commission. Tenant represents that it has dealt with no
broker in connection with this Amendment other than Miglin-Beitler Management
Corporation, and that no other broker is entitled to or has made any claims to
any commission or fee in connection with this Amendment. Tenant hereby
indemnifies, defends and holds harmless Landlord and its agents and employees
from all claims of any broker arising through Tenant in connection with this
Amendment.

         9. Incorporation of Lease. Landlord and Tenant hereby agree that (a)
this Amendment is incorporated into and made a part of the Lease, (b) any and
all references herein to the Lease shall include this Amendment, and (c) the
Lease and all terms, conditions and provisions of the Lease are in full force
and effect as of the date hereof, except as expressly modified and amended
hereinabove.

         10. Defined Terms. All terms capitalized but not defined herein shall
have the same meaning ascribed to such terms in the Lease. The marginal headings
and titles to the paragraphs

                                       6
<PAGE>
 
of this Amendment are not a part of this Amendment and shall have no effect upon
the construction or interpretation of any part hereof.

         11. Governing Law. This Amendment shall be governed by and construed
under the laws of the State of Illinois.

         IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date first above written.


LANDLORD:                                    TENANT:

TIAA REALTY, INC.                            FOCAL COMMUNICATIONS
a Delaware corporation                       CORPORATION OF ILLINOIS
                                             a Delaware corporation
By:  Teachers Insurance and
     Annuity Association of America,
     a New York corporation,
     its authorized representative


By: /s/ S. Marc Flannery                     By: /s/ Brian F. Addy
   -----------------------------                -----------------------------
Name:   S. Marc Flannery                     Name:   Brian F. Addy
     ---------------------------                  ---------------------------
Title:                                       Title:  Executive Vice President
      --------------------------                   --------------------------


                                       7
<PAGE>
 
                                    Exhibit A

                     [Seventh Floor Floorplan Appears Here]






                              THE FLORSHEIM TOWER
                      200 NORTH LASALLE CHICAGO, IL 60601
                   TEACHERS INSURANCE AND ANNUITY ASSOCIATION
                   ------------------------------------------
                     MIGLIN-BEITLER MANAGEMENT CORPORATION
                   (312) 346-1400 UPDATED SEPTEMBER 25, 1998

<PAGE>
 
                                                                 Exhibit 10.10

                            SIXTH AMENDMENT TO LEASE
                            ------------------------


         THIS SIXTH AMENDMENT TO LEASE (this "Amendment") is made and entered
into as of this 18th day of February, 1999 by and between TIAA REALTY, INC., a
Delaware corporation, successor-in-interest to Teachers Insurance and Annuity
Association of America ("Landlord") and FOCAL COMMUNICATIONS CORPORATION OF
ILLINOIS (formerly known as Focal Communications Corporation), a Delaware
corporation, ("Tenant").


                               W I T N E S S E T H
                               -------------------

         WHEREAS, Landlord's predecessor-in-interest ("TIAA") and Tenant have
heretofore entered into that certain lease dated as of December 31, 1996 the
("Original Lease"), pursuant to which Landlord leased to Tenant 10,236 rentable
square feet of certain premises on the lower level (the "Original Space") of the
building commonly known as 200 North LaSalle Street, Chicago, Illinois (the
"Building");

         WHEREAS, TIAA and Tenant have heretofore entered into that certain
First Amendment to Lease dated May 14, 1997 (the "First Amendment") to evidence
Tenant's expansion into the additional space of 6,202 rentable square feet on
the eighth (8th) floor of the Building (the "First Additional Space"), as more
particularly set forth in the First Amendment;

         WHEREAS, TIAA and Tenant entered into that certain Second Amendment to
Lease dated November 15, 1997 (the "Second Amendment") to evidence Tenant's
expansion into the additional space of 4,153 rentable square feet on the eighth
(8th) floor of the Building (the "Second Additional Space"), as more
particularly set forth in the Second Amendment;

         WHEREAS, TIAA and Tenant entered into that certain Third Amendment to
Agreement of Lease dated March 2, 1998 (the "Third Amendment") to evidence
Tenant's installation of a communication device, as more particularly set forth
in the Third Amendment;

         WHEREAS, TIAA and Tenant entered into that certain Fourth Amendment to
Lease dated April 24, 1998 (the "Fourth Amendment") to evidence Tenant's
expansion into the additional space of 11,956 rentable square feet on the
seventh (7th) floor of the Building (the "Third Additional Space"), as more
particularly set forth in the Fourth Amendment;

         WHEREAS, Landlord and Tenant entered into that certain Fifth Amendment
to Lease dated October 14, 1998 (the "Fifth Amendment") to evidence Tenant's
expansion into the additional space of 4,593 rentable square feet on the seventh
(7th) floor of the Building (the "Fourth Additional Space"); collectively (such
Original Space, the First Additional Space, the Second Additional Space, the
Third Additional Space and the Fourth Additional Space are referred to herein as
the "Previous Space" comprising a total of 26,904 rentable square feet),
<PAGE>
 
as more particularly set forth in the Fifth Amendment (such Original Lease as
amended by the First Amendment, the Second Amendment, the Third Amendment, the
Fourth Amendment and the Fifth Amendment and as modified or amended from time to
time, hereafter is called the "Lease");

         WHEREAS, Landlord and Tenant desire to amend the Lease according to the
terms hereof in order to document the extension of the Term of the Lease, the
leasing of additional space on the Ninth and Eleventh Floors of the Building,
and to make such other changes on the terms and conditions set forth below.

         NOW THEREFORE, for and in consideration of the covenants and agreements
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant
hereby mutually agree as follows:

         1. Recitals. The foregoing recitals are true and correct and are
incorporated herein by reference.

         2. Controlling Language. Insofar as the specific terms and provisions
of this Amendment purport to amend or modify or are in conflict with the
specific terms, provisions and exhibits of the Lease, the terms and provisions
of this Amendment shall govern and control; in all other respects, the terms,
provisions and exhibits of the Lease shall remain unmodified in full force and
effect.

         3. Ninth Floor Space/Term. Landlord and Tenant hereby agree that
beginning on July 1, 1999 (the "Ninth Floor Space Commencement Date"), Landlord
shall lease to Tenant approximately 7,900 rentable square feet of space on the
ninth (9th) floor of the Building as more particularly depicted on Exhibit A
attached hereto (the "Ninth Floor Space") for a period of five (5) years ending
on the Extended Term Termination Date (the "Ninth Floor Space Term". The Ninth
Floor Space shall be subject to all the terms and conditions of the Lease except
to the extent expressly modified or excluded hereby or herein and shall be
included in the "Premises" as the term is used in the Lease.

         4. Ninth Floor Space Rent. Effective as of the Ninth Floor Space
Commencement Date and for the duration of the Ninth Floor Space Term, in
addition to (and not in substitution for) the Rent payable with respect to the
Previous Space under the Lease, Tenant shall pay to Landlord Rent with respect
to the Ninth Floor Space as follows:

                  A. Base Rent.

                           (1) Base Rent to be paid in monthly installments in
                           advance on or before the first day of each month of
                           the Ninth Floor Space Term as set forth in the
                           following schedule:


                                       2
<PAGE>
 
<TABLE>
<CAPTION>
Period                                Annual Base Rent                  Monthly Base Rent
- ------------------------------------------------------------------------------------------
<S>                                   <C>                                   <C>
July 1, 1999 - February 29, 2000      $104,675.00 ($13.25 per rentable
                                      square foot x 7,900                   $8,722.92
                                      rentable square feet)
- ------------------------------------------------------------------------------------------
March 1, 2000 - February 28, 2001     $108,625.00 ($13.75 per rentable
                                      square foot x 7,900                   $9,052.08
                                      rentable square feet)
- ------------------------------------------------------------------------------------------
March 1, 2001 - February 28, 2002     $112,575.00 ($14.25 per rentable
                                      square foot x 7,900                   $9,381.25
                                      rentable square feet)
- ------------------------------------------------------------------------------------------
March 1, 2002 - February 28, 2003     $116,525.00 ($14.75 per rentable
                                      square foot  x 7,900                  $9,710.42
                                      rentable square feet)
- ------------------------------------------------------------------------------------------
March 1, 2003 - June 30, 2004         $120,475.00 ($15.25 per rentable
                                      square foot x 7,900                   $10,039.58
                                      rentable square feet)
- ------------------------------------------------------------------------------------------
</TABLE>

                  B. Taxes and Operating Expenses. During the Ninth Floor Space
Term, Tenant shall pay Operating Cost Share Rent, Tax Share Rent and Additional
Rent for the Ninth Floor Space in the manner set forth in the Lease. "Tenant's
Proportionate Share," with respect to the Ninth Floor Space, for calculating
Operating Cost Share Rent, Tax Share Rent and Additional Rent is 1.2687% (based
upon 7,900 rentable square feet in the Ninth Floor Space and 622,667 rentable
square feet in the Building).

         5. Eleventh Floor Space/Term. Landlord and Tenant hereby agree that
beginning on March 1, 1999 (the "Eleventh Floor Space Commencement Date"),
Landlord shall lease to Tenant approximately 22,707 rentable square feet of
space on the eleventh (11th) floor of the Building as more particularly
described on Exhibit B attached hereto (the "Eleventh Floor Space") for a period
of five (5) years, four (4) months ending on the Extended Term Termination Date
(the "Eleventh Floor Space Term". The Eleventh Floor Space shall be subject to
all the terms and conditions of the Lease except to the extent expressly
modified or excluded hereby or herein and shall be included in the "Premises" as
the term is used in the Lease.

         6. Eleventh Floor Space Rent. Effective as of the Eleventh Floor Space
Commencement Date and for the duration of the Eleventh Floor Space Term, in
addition to (and not in substitution for) the Rent payable with respect to the
Previous Space under the Lease, Tenant shall pay to Landlord Rent with respect
to the Eleventh Floor Space as follows:


                                       3
<PAGE>
 
                  A. Base Rent.

                           (1) Base Rent to be paid in monthly installments in
                           advance on or before the first day of each month of
                           the Term of this Lease set forth in the following
                           schedule:

<TABLE>
<CAPTION>
Period                                Annual Base Rent                  Monthly Base Rent
- ------------------------------------------------------------------------------------------
<S>                                   <C>                                   <C>
March 1, 1999 - February 29, 2000     $300,867.75 ($13.25 per rentable      $25,072.31
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
March 1, 2000 - February 28, 2001     $312,221.25 ($13.75 per rentable      $26,018.44
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
March 1, 2001 - February 28, 2002     $323,574.75 ($14.25 per rentable      $26,964.56
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
March 1, 2002 - February 28, 2003     $334,928.25 ($14.75 per rentable      $27,910.69
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
March 1, 2003 - February 28, 2004     $346,281.75 ($15.25 per rentable      $28,856.81
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
March 1, 2004 - June 30, 2004         $346,281.75 ($15.25 per rentable      $28,856.81
                                      square foot x 22,707 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
</TABLE>

                  B. Taxes and Operating Expenses. During the Eleventh Floor
Space Term, Tenant shall pay Operating Cost Share Rent, Tax Share Rent and
Additional Rent for the Eleventh Floor Space in the manner set forth in the
Lease. "Tenant's Proportionate Share" with respect to the Eleventh Floor Space,
for calculating Operating Cost Share Rent, Tax Share Rent and Additional Rent is
3.6467% (based upon 22,707 rentable square feet in the Eleventh Floor Space and
622,667 rentable square feet in the Building).

         7. Extension of Term. The Term of the Lease for the Previous Space is
hereby extended for an additional period of one (1) year (the "Extended Term")
commencing on July 1, 2003 (the "Extended Term Commencement Date") and ending
twelve (12) calendar months thereafter on June 30, 2004 (the "Extended Term
Termination Date").

         8. Extended Term Rent. Effective as of the Extended Term Commencement
Date, in addition to any and all rent payable under the Lease, Tenant shall pay
rent as follows:

                                       4
<PAGE>
 
                  A. Base Rent.

                           (1) Base Rent to be paid in monthly installments in
                           advance on or before the first day of each month of
                           the Extended Term as follows:

<TABLE>
<CAPTION>
Period                                Annual Base Rent                  Monthly Base Rent
- ------------------------------------------------------------------------------------------
<S>                                   <C>                                   <C>
July 1, 2003- June 30, 2004           $410,286.00 ($15.25 per rentable      $34,190.50
                                      square foot x 26,904 rentable
                                      square feet)
- ------------------------------------------------------------------------------------------
</TABLE>

                  B. Taxes and Operating Expenses. During the Extended Term,
Tenant shall pay Operating Cost Share Rent, Tax Share Rent and Additional Rent
for the Previous Space in the manner set forth in the Lease. "Tenant's
Proportionate Share," with respect to the Previous Space, for calculating
Operating Cost Share Rent, Tax Share Rent and Additional Rent is 4.3208% (based
upon 26,904 rentable square feet in the Previous Space and 622,667 rentable
square feet in the Building).

         9. Condition of the Ninth Floor Space and the Eleventh Floor Space.
Except to the extent expressly provided herein, Landlord is leasing the Ninth
Floor Space and the Eleventh Floor Space to Tenant on the Ninth Floor Space
Commencement Date and the Eleventh Floor Space Commencement Date, respectively,
in its then-"AS IS" condition, without any representations or warranties of any
kind (including, without limitation, any express or implied warranties of
merchantability, fitness or habitability) and without any obligation on the part
of Landlord to alter, remodel, improve, repair, or decorate either the Ninth
Floor Space or the Eleventh Floor Space or any part thereof.

         10. Brokerage Commission. Tenant represents that it has dealt with no
broker in connection with this Amendment other than Douglas Elliman-Beitler
Management Corporation ("Broker"), and that no broker other than Broker is
entitled to or has made any claims to any commission or fee in connection with
this Amendment. Tenant hereby indemnifies, defends and holds harmless Landlord
and its agents and employees from all claims of any broker other than Broker
arising through Tenant in connection with this Amendment. Landlord agrees to pay
any real estate commissions which may be due Broker pursuant to Landlord's
written agreement with such Broker.

         11. Condition. The obligation of Landlord to consummate the
transactions contemplated hereunder is expressly contingent upon Landlord timely
repossessing the Ninth Floor Space and the Eleventh Floor Space from the current
tenant of such spaces.

         12. Incorporation of Lease. Landlord and Tenant hereby agree that (a)
this Amendment is incorporated into and made a part of the Lease, (b) any and
all references herein

                                       5
<PAGE>
 
to the Lease shall include this Amendment, and (c) the Lease and all terms,
conditions and provisions of the Lease are in full force and effect as of the
date hereof, except as expressly modified and amended hereinabove.

         13. Defined Terms. All terms capitalized but not defined herein shall
have the same meaning ascribed to such terms in the Lease. The marginal headings
and titles to the paragraphs of this Amendment are not a part of this Amendment
and shall have no effect upon the construction or interpretation of any part
hereof.

         14. Governing Law. This Amendment shall be governed by and construed
under the laws of the State of Illinois.




                                       6
<PAGE>
 
         IN WITNESS WHEREOF, the parties have executed this Amendment as of the
date first above written.


LANDLORD:                                    TENANT:

TIAA REALTY, INC.,                           FOCAL COMMUNICATIONS
a Delaware corporation                       CORPORATION OF ILLINOIS,
                                             a Delaware corporation
By:      Teachers Insurance and Annuity
         Association of America


         By: /s/ S. Marc Flannery            By: /s/ John Barnicle
            ---------------------------         -------------------------
         Name:   S. Marc Flannery            Name:   John Barnicle
              -------------------------           -----------------------
         Title:  Director                    Title:  C.O.O.
               ------------------------            ----------------------







                                       7
<PAGE>
 
                                    Exhibit A

                     [Ninth Floor Space Plan Appears Here]
<PAGE>
 
                                    Exhibit B

                    [Eleventh Floor Space Plan Appears Here]

<PAGE>
 
                                                                   EXHIBIT 10.11

                           FIRST AMENDMENT TO LEASE


          THIS FIRST AMENDMENT TO LEASE (this "AMENDMENT"), dated as of the 3rd
day OF March 1998, is entered into by and between ZORO, LLC, a California
limited liability company ("Landlord"), FOCAL COMMUNICATIONS CORPORATION, a
Delaware corporation ("Tenant"). Capitalized terms used in this Amendment
without definition shall have the meanings ascribed to such terms in the Lease
(as hereinafter defined).

          THE PARTIES ENTER into this Amendment on the basis of the following
facts, understandings and intentions:

          A.  Landlord and Tenant entered into that certain Lease dated January
26, 1998 (the "Lease"), whereby Landlord leased to Tenant and Tenant leased from
Landlord certain premises more particularly described therein (the "Premises"),
located in the second floor of the building owned by Landlord at 650 Townsend
Street, San Francisco, California (the "Building").

          B.  Landlord and Tenant desire to amend the Lease to provide for the
construction and installation of the Tenant Auxiliary and Emergency Power
Facility (the "Facility") to serve Tenant and another tenant of the Building,
Ziff-Davis Inc. ("ZD") (collectively the "Phase One Tenants"), and to provide
for expansion of the Facility at the request of Landlord.

          NOW, THEREFORE, based on the foregoing and for other good and valuable
consideration, the receipt and adequacy of which is hereby acknowledged, the
parties agree as follows:

     1.   Tenant Auxiliary and Emergency Power Facility.  Landlord acknowledges
          ---------------------------------------------                       
that it has been unable to reach agreement with the Auxiliary Power Provider for
the construction and installation of the Shared Auxiliary and Emergency Power
Facility contemplated by Section 6.3(b) of the Lease. Landlord hereby designates
the location described in Exhibit A to this First Amendment as the location
designated by Landlord under Section 6.3(b) of the Lease as the location in the
Building where Tenant may construct the

                                       1
<PAGE>
 
Facility (the "Approved Auxiliary and Emergency Power Facility Location"),
subject to the conditions of this Amendment. Tenant hereby accepts and approves
of the Approved Auxiliary and Emergency Power Facility Location and agrees to
construct and install thereon, subject to the approval of Landlord as provided
in Paragraph 3 of this First Amendment, at Tenant's sole cost and expense,
subject to reimbursement as provided in Paragraph 4 of this First Amendment, the
following:

                (i) an emergency generator providing 1,000 kilowatts of power
                (the "Phase One Generator"), (ii) supplemental chiller equipment
                with the capacity of 400 tons of cooling (the "Phase One
                Chiller"), and (iii) related conduit, cabling and infrastructure
                to accommodate the Phase One Generator and Phase One Chiller
                (hereinafter, collectively "Phase One").

     2.   TRANSFORMER AND FUEL TANK. Landlord will cause to be constructed and
          -------------------------                                           
installed, at Landlord's sole cost and expense, subject to reimbursement as
provided in Paragraph 4 hereof, (i) a transformer and related equipment to
distribute the electrical power generated by the Phase One Generator (the
"Transformer"), and (ii) an above ground, shared fuel tank (the "Fuel Tank") to
support the Facility, of a size not less than that required to met the Phase One
requirements, in the location noted for such fuel tank in the Approved Auxiliary
and Emergency Power Facility Location. Landlord shall coordinate such
construction and installation with Tenant's contractor.
 
     3.   APPROVAL OF PLANS AND SPECIFICATIONS. Tenant's contractor for the
          ------------------------------------
installation and construction of the Facility shall be selected by Tenant and
approved by Landlord in accordance with Section 9.1(b) of the Lease, and
Tenant's plans and specifications with respect to the work shall be prepared by
Tenant, with the advice and consultation of Landlord's consultants, and
submitted to Landlord for Landlord's approval in accordance with Section 9.2 of
the Lease. Tenant agrees to design the Facility to the following capacities,
notwithstanding that users for such capacity may not be operating in the
Building and have a demand for such auxiliary and emergency power services as of
the date hereof.
                                             Phase One    Phase Two   Total

               (i)   Emergency Generator     1,000 kw     1,250 kw    2,250kw
               (ii)  Chiller                 400 tons     200 tons    600 tons

                                       2
<PAGE>

               and otherwise in accordance with Paragraph 1 of this First
               Amendment.

     4.   ALLOCATION AND RESPONSIBILITY FOR COST.
          -------------------------------------- 

          (a)  Oversizing. Landlord will reimburse Tenant, following lien free
               ----------                                                     
completion of the Facility, for the incremental additional cost associated with
the design and construction of the Facility over and above the Phase One
capacities described in Paragraph 1 above. The incremental cost shall be
initially determined by Tenant, and shall be limited to Tenant's actual out-of-
pocket costs of design and installation, and construction, and documentation in
support of such charges shall be submitted to Landlord in reasonably sufficient
detail to enable Landlord to review Tenant's determination and calculation of
such incremental costs. Any dispute between the parties shall be resolved as
described in paragraph 8 ("Arbitration").

          (b)  Transformer. Tenant will reimburse Landlord, following lien free
               -----------                                                     
completion of the Transformer, for the actual out-of-pocket costs of design,
acquisition and installation of the Transformer. The actual costs with respect
thereto be shall initially determined by Landlord, and documentation in support
of such charges shall be submitted to Tenant in reasonably sufficient detail to
enable Tenant to review Landlord's determination and calculation of such costs.
Any dispute between the parties shall be resolved by Arbitration.

          (c)  Fuel Tank. Tenant shall reimburse Landlord, following lien free
               ---------
completion of the Fuel Tank, for the actual out-of-pocket costs of design,
construction and installation of a 10,000 gallon capacity Fuel Tank (the "Base
Fuel Tank Cost"), with the incremental cost in excess of the Base Fuel Tank Cost
(the "Incremental Tank Cost") being borne by Landlord. The Base Fuel Tank Cost
and the Incremental Tank Cost shall be initially determined by Landlord, and
documentation in support of such charges shall be submitted to Tenant in
reasonably sufficient detail to enable Tenant to review Landlord's determination
and calculation of such incremental costs. Any dispute between the parties shall
be resolved by Arbitration.

                                       3
<PAGE>
 
          (d)  ZD. Tenant agrees to enter into arrangements with ZD, on terms
               --
and conditions acceptable to both parties, allocating to ZD the right to use up
to 500 kw of power from the Facility Phase One Generator, and 100 tons of
chilled water from the Phase One Chiller. Subject to the foregoing, the amount
of kilowatt power capacity made available to ZD shall be as determined by ZD.
Tenant shall be solely responsible for entering into such arrangements as it
deems appropriate for the reimbursement of its costs from ZD. Except as
otherwise agreed by ZD, Tenant shall only charge ZD for Tenant's actual costs
for emergency and auxiliary power and auxiliary cooling capacity and shall not
require ZD to pay for such services other than on a rental or lease basis (i.e.,
no contribution or payment of capital).

          (e)  Other Building Tenants. Tenant agrees to cooperate with Landlord
               ----------------------                                          
and/or other Building tenants (the "Subsequent Users") to whom Landlord grants
rights to use the Phase Two capacity of the Facility, including providing
interconnection to the chiller being designed and installed as part of the
Facility. For so long as Tenant is providing maintenance and repair services
with respect to the Facility, Landlord shall condition Subsequent Users' use of
the excess capacity of the chiller on their entering into arrangements for
reimbursement with Tenant for Tenant's maintenance and repair expenses
associated with the chiller; provided, however, Tenant shall only charge
Subsequent Users for its actual costs of maintenance and repair.

     5.   INDEMNIFICATION. Tenant agrees that the obligation to provide ZD with
          ---------------
an allocation of electrical power capacity from the Tenant Auxiliary and
Emergency Power Facility is an obligation that Landlord has to ZD under a
separate lease entered into by Landlord and ZD (the "ZD Lease"). Tenant
understands that the terms of this First Amendment allocate to Tenant the
responsibility for performing an obligation that Landlord is otherwise obligated
to perform under the ZD Lease. So long as ZD does not demand more of Tenant with
respect to the use of the Tenant Auxiliary and Emergency Power Facility than is
provided in this First Amendment as allocable to ZD, Tenant agrees that any
breach or default by Tenant under the terms of Paragraph 4(c) of this First
Amendment shall be an occurrence subject to the indemnification provision of
Section 10.1 of the Lease, including

                                       4
<PAGE>
 
(notwithstanding anything to the contrary in the Lease), for any actual damages
incurred by Landlord as a result thereof.

     6.   Ownership and Removal of Tenant Auxiliary and Emergency Power
          -------------------------------------------------------------
Facility Upon Expiration of Term. Notwithstanding anything to the contrary in
- --------------------------------                                             
the Lease, Tenant shall be responsible for any and all maintenance, repair and
replacement of the Tenant Auxiliary and Emergency Power Facility, at its sole
cost and expense. Upon expiration of the Term of the Lease, the Facility shall
revert to Landlord at no cost.

     7.   Placement Charge. The placement and use charge provided in Section
          ----------------
6.3(c) of the Lease is expressly made applicable to the Facility.

     8.   Arbitration. In the event that any controversy or dispute shall arise
          -----------
under Paragraph 4 hereof, the parties shall first try in good faith to settle
the dispute by mediation administered by the Judicial Arbitration & Mediation
Service, 2 Embarcadero Center, San Francisco, California ("JAMS"). Thereafter
any remaining unresolved controversy or claim arising out of or relating to such
matter shall be settled by binding arbitration administered by the JAMS or, if
JAMS no longer exists, to any similar organization mutually acceptable to the
parties, and judgment upon the award rendered by the arbitrator may be entered
in any court of competent jurisdiction. Unless otherwise agreed to by the
parties, the matter shall be submitted to one (1) arbitrator and shall be heard
in San Francisco, California. The parties shall have three (3) business days
after the matter is submitted to arbitration to agree upon the neutral
arbitrator from the available panel. If the parties are unable to agree within
that three (3) days period, any party may request the appropriate official at
JAMS to appoint the arbitrator from its panel and that appointment shall be
binding upon the parties to the arbitration. The arbitrator chosen by the
parties or appointed by JAMS shall be a retired Federal District Court,
California Superior Court, or federal or state appellate court judge with at
least ten (10) years experience on the bench. The arbitrators shall resolve the
controversy in accordance with applicable law and the terms and conditions of
this Lease. The arbitrators shall allow the parties reasonable opportunities for
pre-hearing document exchange and other pre-hearing discovery of evidence as
determined by the arbitrator in his or her discretion. The costs of the
arbitration shall be shared equally between the parties

                                       5
<PAGE>
 
provided, however, that such costs along with all other costs and expenses,
including attorneys' fees, shall be subject to award in full or in part by the
arbitrators in the arbitrators' discretion to the prevailing party.

     9.   LANDLORD RIGHT TO TAKE OVER MAINTENANCE. If, at any time, Landlord, in
          ---------------------------------------                               
its reasonable discretion, is not satisfied with the level of performance, or
quality of maintenance and repair of or to the Facility being provided by Tenant
under this First Amendment, or if Tenant fails to provide interconnection to the
Facility to Subsequent Users to utilize the Phase Two capacity being designed
into the Facility as provided in this First Amendment, Landlord may notify
Tenant in writing of its objection to such services. Tenant shall have ten (10)
days to commence to cure any identified deficiencies. If after ten (10) days
Landlord finds, in its reasonable discretion, that the deficiencies have not
been cured, it shall notify Tenant in writing of the failure to cure and of the
specific deficiencies that have not been cured. Tenant shall have an additional
five (5) days to effect a cure. If after such five (5) day period, Landlord
finds, in its reasonable discretion, that the maintenance and repair of the
Facility is still not satisfactory, or that Tenant has still not provided
interconnection to the Facility as hereinabove provided, Landlord may take over
the maintenance and repair responsibilities of the Facility (hereinafter the
"Changeover"). In such case, Landlord shall so notify Tenant in writing at least
ten (10) days prior to the date of Changeover. Tenant shall thereupon transfer
to Landlord (or Landlord's designee) all books, records, plans and
specifications with respect to the Facility and shall otherwise cooperate with
the Landlord in arranging the Changeover. If Landlord elects to cause the
Changeover, provide its own maintenance and repair services, rent payable under
the Lease shall be adjusted to reflect the costs of providing the service of the
Facility (including appropriate management fees) for Tenant's use. Such charges
may be assessed against Tenant separately or may be included as an additional
item of Operating Expenses.

                                       6
<PAGE>
 
     10.  FULL FORCE AND EFFECT. Except as amended hereby, the Lease remains
          ---------------------                                            
unamended, and as amended hereby the Lease is in full force and effect.


          IN WITNESS WHEREOF, the parties hereto have executed this Amendment as
of the day and year first above written.

                             "LANDLORD"

                             ZORO, LLC,
                             A California limited liability company

                             By:  /s/ [SIGNATURE ILLEGIBLE]^^
                                -------------------------------------

                             Its: Managing Member
                                 ------------------------------------


                             "TENANT"

                             FOCAL COMMUNICATIONS CORPORATION,
                             a Delaware corporation,
                             

                             By: /s/ [SIGNATURE ILLEGIBLE]^^
                                -------------------------------------  

                             Its:  Executive Vice President
                                 ------------------------------------

                                       7
<PAGE>
 
                         [PLAN OF LOADING DOCK LEVEL]



                                  EXHIBIT "A"
                                  SHEET #1
                                  (LOADING DOCK LEVEL)

<PAGE>
 
                                  EXHIBIT "A"
                                  SHEET #2
                                  (ROOF LEVEL)

                           [ROOF PLAN APPEARS HERE]


<PAGE>
 
                                                                   EXHIBIT 10.12

                           SECOND AMENDMENT TO LEASE

          THIS SECOND AMENDMENT TO LEASE (this "Amendment"), dated as of June
                                                                             
16/TH/ 1998, is entered into by and between ZORO, LLC, a California limited
liability company ("Landlord"), FOCAL COMMUNICATIONS CORPORATION, a Delaware
corporation ("Tenant"). Capitalized terms used in this Amendment without
definition shall have the meanings ascribed to such terms in the Lease (as
hereinafter defined).

          THE PARTIES ENTER into this Amendment on the basis of the following
facts, understandings and intentions:

          A.  Landlord and Tenant entered into that certain Lease dated January
26, 1998 (the "Original Lease"), whereby Landlord leased to Tenant and Tenant
leased from Landlord certain premises more particularly described therein (the
"Premises"), located in the second floor of the building owned by Landlord at
650 Townsend Street, San Francisco, California (the "Building").

          B.  The parties entered into a First Amendment to Lease (the "First
Amendment") dated as of March 3, 1998 (the Original Lease, as amended by the
First Amendment is referred to herein as the "Lease").

          C.  The First Amendment contemplates the construction and installation
of a Shared Auxiliary and Emergency Power Facility.

          D.  The parties wish to amend the First Amendment to provide for the
specific equipment to be incorporated into the Facility, and the allocation of
costs to be incurred in the design and installation of said equipment.

          NOW, THEREFORE, based on the foregoing and for other good and valuable
consideration, the receipt and adequacy of which is hereby acknowledged, the
parties agree as follows:

                                       1
<PAGE>
 
     1.   Auxiliary And Emergency Power Facility. 
          -------------------------------------- 

          (a)  Landlord and Tenant hereby agree that, notwithstanding anything
to the contrary in the First Amendment, Tenant shall engage and supervise the
Approved Contractor (as hereinafter defined) for the construction and
installation of the following:

             (i) a 1,250 kilowatt emergency generator (the "Generator"), (ii)
             supplemental chiller equipment with the capacity of 250 tons of
             cooling (the "Chiller"), (iii) related conduit, cabling and
             infrastructure to accommodate the Generator and the Chiller,
             including, without limitation, an electrical switch / distribution
             panel and related equipment capable of distributing up to 4,000
             amperes of power for Tenant and Subsequent Users of which Tenant
             shall have the right to utilize 2,000 amperes (provided Tenant
             shall not be responsible to provide conduit, cabling and
             infrastructure for such Subsequent Users), and (iv) an above-
             ground, 9,000 gallon capacity, fuel tank (the "Fuel Tank") capable
             of serving an additional user or users.

The foregoing improvements and components are hereinafter referred to as the
"Facility" and such term shall supersede and replace the definition of said term
as used in the First Amendment. In accordance with Section 9.1(b) of the
Original Lease, Landlord hereby approves Swinerton and Walberg (the "Approved
Contractor") as the contractor for the installation and construction of the
Facility. Except as provided in subparagraph (b) hereof, the provisions of
Section 9.1 of the Lease relating to Tenant's obligations with respect to
Alterations shall be deemed applicable to Tenant's work with respect to the
Facility.

          (b)  Notwithstanding anything to the contrary in Section 9.1(c) of the
Original Lease, Landlord agrees that the construction management fee charged to
Tenant in connection with Landlord's review and coordination of the design,
construction and installation of the Facility shall be $90,000.

          (c)  Tenant's plans and specifications with respect to the Facility
shall be prepared by Tenant, with the advice and consultation of Landlord's
consultants, and submitted to Landlord for Landlord's approval in accordance
with Section 9.2 of the Original Lease.

          (d)  The Phase One capacities provided in Paragraph 3 of the First
Amendment are hereby amended and restated as follows:

                                       2
<PAGE>
 
                                             Phase One
            (i)   Generator                  1,250 kw
            (ii)  Chiller                      250 tons
            (iii) Transformer                4,000 amps
            (iv)  Fuel Tank                  9,000 gallons

          (e)  Paragraph 1 of the First Amendment shall be deemed amended to the
extent inconsistent with this Paragraph, and Paragraphs 2 and 3 of the First
Amendment are hereby deleted in their entirety and are of no further force and
effect. Without limiting the generality of the foregoing, all references in the
First Amendment to "Phase Two" are hereby deleted.

     2.   Allocation And Responsibility For Cost.
          -------------------------------------- 

          (a)  Notwithstanding anything to the contrary in the First Amendment,
Tenant shall be solely responsible for the entire cost and expense associated
with the design, construction and installation of the Facility; provided,
however, Landlord will reimburse Tenant following lien free completion of the
Facility for that portion of the cost and expense thereof equal to the lesser of
(i) Two Hundred Fifty Thousand Dollars ($250,000), or (ii) eight percent (8%) of
Tenant's out-of-pocket costs and expenses in connection with the design,
construction and installation of the Facility, including Landlord's construction
management fees (Landlord's share of such cost and expense as hereinabove
determined is hereinafter referred to as "Landlord's Share"). Tenant's shall
provide Landlord with documentation in support of any request for reimbursement
of Landlord's Share in reasonably sufficient detail to enable Landlord to review
Tenant's determination and calculation of Landlord's Share. Any dispute between
the parties shall be resolved by Arbitration as provided in the First Amendment.

          (b)  Paragraphs 4(a) - (c) of the First Amendment are hereby deleted
in their entirety and are of no further force and effect.

     3.   Future Capacity.
          ---------------

          (a)  Landlord shall have the right, from time to time, upon no less
than thirty (30) days prior written notice, to add to the Facility generator and
chiller units or modules

                                       3
<PAGE>
 
providing additional capacity. In so doing, Landlord shall use reasonable
efforts not to disrupt Tenant's use of the Facility, Generator and Chiller units
or modules without Tenant's consent which shall not be unreasonably withheld.
Tenant agrees to cooperate with Landlord and/or other Building tenants (the
"Subsequent Users") to whom Landlord grants rights to use the Facility. For so
long as Tenant is providing maintenance and repair services with respect to the
Facility, Landlord shall condition Subsequent Users' use of the excess capacity
of the chiller on their entering into arrangements for reimbursement with Tenant
for Tenant's maintenance and repair expenses associated with the chiller;
provided, however, Tenant shall only charge Subsequent Users for its actual
costs of maintenance and repair.

          (b)  Without limiting the generality of the terms of Paragraph 3(a)
above, Tenant agrees that at all times during the term of the Lease, Landlord
shall have the right to allocate to Subsequent Users the use of fuel from the
Fuel Tank in the aggregate amount of thirty percent (30%) of the Fuel Tank
capacity. but in no event less than 3,000 gallons (the "Landlord Gallon
Allocation"). The use by Tenant (or the allocation by Tenant to ZD) of fuel in
excess of an amount that enables Landlord to use or to allocate to Subsequent
Users the Landlord Gallon Allocation shall be deemed an Event of Default (as
defined in Article 9 of the Lease) under the Lease.

          (c)  If ZD does not utilize the capacity allocated to ZD under the
terms of Paragraph 4(d) of the First Amendment, Tenant may re-sell such capacity
to other tenants of the Building, or to Landlord, at a price and on terms as may
be mutually agreed upon, but otherwise subject to the terms of the Lease, as
amended hereby.

          (d)  Paragraph 4(e) of the First Amendment is hereby deleted in its
entirety, and is of no further force and effect.

     4.   TIMING. Subject to Landlord's approval of detailed plans and
          ------
specifications with respect to the Facility, Tenant shall commence installation
and construction of the Facility on or before July 1, 1998. Subject to delays
attributable to Force Majeure (as that term is defined in the Lease), and delays
which are attributable to Tenant, its agents, affiliates, employees,
contractors, or any entity formed by Tenant to install the Facility, Tenant
shall

                                       4
<PAGE>
 
substantially complete the construction and installation of the Fuel Tank (as
defined in Section 1(a) above) (and the same shall be fully operational) on or
before September 30, 1998.

     5.   Letter of Credit. In order to secure the performance by Tenant of its
          ----------------                                                     
obligations under the Lease, as amended by this Amendment, with respect to the
design, construction and installation of the Facility, Tenant shall obtain and
deliver to Landlord prior to commencement of any actual work in the Building an
irrevocable standby letter of credit issued by the California office of a United
States bank authorized to conduct banking business in the State of California,
in the amount of $3,000,000 (the "Letter of Credit"). The expiry date of the
Letter of Credit shall be December 31, 1998. Landlord shall be entitled to draw
on the entire sum of the Letter of Credit upon Landlord's declaration of an
Event of Default under the Lease resulting from Tenant's default under its
obligations under this Amendment, and no other act or notice shall be required
by Landlord in order to be entitled to draw on the entire sum of the Letter of
Credit. The remedy in the preceding sentence shall be Landlord's sole remedy
upon an Event of Default under the Lease resulting from Tenant's default under
its obligations under this Amendment. Landlord shall apply the proceeds of the
Letter of Credit to pay (i) any mechanic's or materialmen's liens arising from
construction of the Facility and/or (ii) to complete construction of the
Facility and sums remaining after payment of such sums (including, without
limitation, any attorneys' fees of Landlord) shall be returned to Tenant
following substantial completion of the Facility. Landlord shall return the
unused portion of the Letter of Credit to Tenant upon completion of the Facility
in accordance with, and as required by the terms of, Paragraph 4 of this
Amendment. The form and substance of the Letter of Credit in a manner consistent
with this Paragraph 5 shall be acceptable in all respects to Landlord.

     6.   Full Force and Effect. Except as amended hereby, the Lease remains
          ---------------------                                             
unamended, and as amended hereby the Lease is in full force and effect.

                                       5
<PAGE>
 
          IN WITNESS WHEREOF, the parties hereto have executed this Amendment as
of the day and year first above written.


                                   "LANDLORD"

                                   ZORO, LLC,
                                   a California limited liability company

                                   By: /s/ [SIGNATURE ILLEGIBLE]^^
                                      -----------------------------------

                                   Its:  MANAGING MEMBER
                                       ----------------------------------


                                   "TENANT"

                                   FOCAL COMMUNICATIONS CORPORATION,
                                   a Delaware corporation,


                                   By: /s/ [SIGNATURE ILLEGIBLE]^^
                                      -----------------------------------

                                   Its: EVP
                                       ----------------------------------

                                       6

<PAGE>

                                                                   EXHIBIT 10.13

                           THIRD AMENDMENT TO LEASE
                           ------------------------

     THIS THIRD AMENDMENT TO LEASE (this "Third Amendment") dated as of this
16/th/ day of February, 1999, is entered into by and between ZORO, LLC, a
California limited liability company ("Landlord"), and FOCAL COMMUNICATIONS
CORPORATION, a Delaware corporation ("Tenant").

     The Parties enter into this Third Amendment on the basis of the following
facts, understandings and intentions:


                                   RECITALS


     A.   Capitalized terms used in this Third Amendment without definition
shall have the meanings ascribed to such terms in the Original Lease (as
hereinafter defined).

     B.   Landlord and Tenant entered into that certain Lease dated January 26,
1998 ("Original Lease"), whereby Landlord leased to Tenant and Tenant leased
from Landlord certain premises more particularly described therein (the
"Original Premises"), located on the second floor of the building owned by
Landlord at 650 Townsend Street, San Francisco, California (the "Building").

     C.   Landlord and Tenant subsequently entered into that certain First
Amendment to Lease dated March 3, 1998 and that certain Second Amendment to
Lease dated June 16, 1998. (The Original Lease and the First and Second
Amendments are collectively referred to herein as the "Lease").

     D.   Tenant desires to lease additional space in the Building (the
"Expansion Premises"). The Expansion Premises consist of approximately 2,654
Adjusted Rentable Square Feet as identified on the floor plan attached as
Exhibit A-1 hereto.

     E.   Landlord and Tenant also desire to amend the Lease to reflect an
increase in the Adjusted Rentable Square Footage of the Building of which the
Original and Expansion Premises are a part from 666,711 Adjusted Rentable Square
Feet to 670,604 Adjusted Rentable Square Feet after measurement by Landlord's
consultant in or about July, 1998.

     F.   Landlord and Tenant desire to amend the Lease to provide for the
Expansion Premises, to reflect the correct total Adjusted Rentable Square Feet
for the entire Building, to modify the Base Rent, and certain other matters as
provided herein.

                                       1.
<PAGE>
 
          NOW, THEREFORE, in consideration of the agreements herein contained,
and for other good and valuable consideration, the receipt and adequacy of which
is hereby acknowledged, Landlord and Tenant agree as follows:



                                  AGREEMENTS



1.   THE EXPANSION PREMISES.

     1.1  Delivery of Expansion Premises. Landlord shall deliver the Expansion
          ------------------------------                                      
Premises to Tenant within thirty (30) days after execution of this Third
Amendment ("The Expansion Premises Delivery Date").

     1.2  AS-IS Condition. The Expansion Premises is delivered to Tenant in an
          ---------------     
"AS-IS" condition and without any obligation on the part of Landlord to perform
any improvements. Except as expressly stated in this Third Amendment, Landlord
disclaims any warranties with respect to the condition, suitability, fitness or
merchantability of the Expansion Premises, and Tenant agrees that it is relying
upon its own examination of the condition of the Expansion Premises.

     1.3  Tenant's Improvements.
          --------------------- 

          (a)    After the Expansion Premises Delivery Date, Tenant agrees to
perform, at its sole cost and expense, the following construction work
(hereafter "Tenant's Improvements"): (i) Install building standard carpet and
paint; (ii) remove existing demising wall within the Expansion Premises; and
(iii) Tenant shall connect all electrical circuitry for the Expansion Premises
to the electric meter presently servicing the Original Premises. Upon expiration
of the Expansion Premises Term, at Landlord's option, Landlord may require
Tenant to reconnect the electrical service for the Expansion Premises to the
Building's electric meter.

          (b)    Tenant's Improvements shall be constructed with the Landlord's
contractor and consultants and shall be directly supervised by Landlord's
Project Manager. In consideration of the supervisory, logistical and review work
to be performed by Landlord in connection with Tenant's Improvements, Tenant
agrees to pay Landlord a "Coordination Fee" equal to $2,654.00. Such
coordination fee shall be paid within ten (10) days of billing by Landlord.

          (c)    Tenant shall contract directly with Landlord's contractor and
consultants to construct Tenant's Improvement.

                                       2.
<PAGE>
 
          (d)    Tenant acknowledges that Landlord has established procedures
for relations with the Building and Planning Departments of the City and County
of San Francisco and that Tenant, Tenant's representatives, architects, or
agents shall not contact any representatives of the City and County of San
Francisco without the presence of Landlord's representative to assure
consistency of treatment of the Building and its tenants by such governmental
agencies. Any such contact by Tenant's representatives in contravention of this
provision which causes an alteration in governmental treatment of the Building
which results in additional costs to the Building or any tenant therein, shall
be borne by the Tenant.

          (e)    Subject to the provisions of paragraph 1.3(d), Tenant shall be
solely responsible for obtaining all necessary governmental approvals and
permits (including but not limited to the approval of the San Francisco City
Planning Department) required to commence and complete the Tenant's Improvements
after obtaining the prior approval of Landlord before making any submittal to
any governmental agency for permit, which approval of Landlord shall not be
unreasonably withheld; and immediately upon receipt thereof, Tenant shall
deliver copies of all such approvals and permits to Landlord.

          (f)    Except as expressly set forth to the contrary in the Lease with
respect to Code Compliance, it shall be Tenant's sole responsibility to satisfy
all applicable building code requirements and governmental rules and regulations
concerning the design and construction of the Tenant's Improvements. Tenant
acknowledges that applying for necessary governmental approvals and permits may,
as a consequence, require Tenant to construct improvements beyond those
contemplated in Section 1.3(a). Tenant, at its sole cost and expense, shall
construct any and all improvements, charges and alterations required by
governmental authorities by reason of applying for governmental permits or
actually constructing Tenant's Improvements including, without limitation, Life
Safety review compliance, ADA, etc.

    1.4   Adjusted Rentable Floor Area. Within thirty (30) days of the Expansion
          ----------------------------                                          
Premises Delivery Date, Landlord's Contractor or Architect, at Tenant's expense,
shall measure the Expansion Premises to determine the exact Adjusted Rentable
Area of the Expansion Premises. Such determination shall be binding upon
Landlord and Tenant and the parties shall execute a letter agreement confirming
the Adjusted Rentable Area. Base Rent and other charges shall be proportionately
adjusted to reflect any change in the Adjusted Rentable Floor area from 2,654
square feet.

2.   LEASE AMENDMENT.

     Effective upon the Expansion Premises Delivery Date, the Lease shall,
without further documentation, be amended as follows:

     2.1  Expansion Premises Term. The term of the Lease for the Expansion Space
          -----------------------                                               
only shall commence on the Expansion Premises Delivery Date and shall expire on
- ----
the last day of the month immediately following the expiration of five (5)
calendar years ("the Expansion Premises Term"). There are no option(s) to renew
the term.

                                       3.
<PAGE>
 
     2.2  Premises. Effective upon the Expansion Premises Delivery Date, the
          --------
Expansion Premises shall be added to the description and size of the Original
Premises. Subject to adjustment as provided in Section 1.4 of this Third
Amendment, the total size of the Original Premises and Expansion Premises is
20,151 square feet of Adjusted Rentable Area. Upon expiration of the Expansion
Premises Term, the size of the Premises shall be reduced to the Adjusted
Rentable Area for the Original Premises.

     2.3  Base Rent. Base Rent payable by Tenant during the Expansion Premises
          ---------      
Term shall be increased by Six Thousand Six Hundred Thirty Five Dollars ($6,635)
per month, Seventy Nine Thousand Six Hundred Twenty Dollars ($79,620) per year
($30 per square foot per year of Adjusted Rental Area applicable to the
Expansion Premises only).

     2.4  Additional Charges. Effective upon the Expansion Premises Delivery
          ------------------                                                
Date and continuing until the expiration of the Expansion Premises Term, all
provisions of the Lease requiring payment by Tenant of a pro rata share which is
based upon the Adjusted Rentable Area of Tenant's premises. (Basic Lease
Information, Item N) shall be based upon the aggregate total of Adjusted
Rentable Area contained in the Expansion Premises and the Original Premises.
Subject to adjustment as provided in Section 1.4, Tenant's aggregate Percentage
Share during the Expansion Premises Term is 3.01%.

     2.5  Security Deposit. Concurrently with the execution of this Third
          ----------------
Amendment, the Security Deposit referenced as Item M, Basic Information of the
Lease, shall be increased by payment to Landlord of Six Thousand Six Hundred
Thirty Five Dollars ($6,635). Subject to the terms of Sections 3.5(b), (c) and
(d), Landlord shall refund to the increased Security Deposit amount of $6,635 to
Tenant upon expiration of the Expansion Premises Term.

     2.6  Building Construction. Tenant acknowledges that the Building is a
          ---------------------                                            
redevelopment project and is currently undergoing construction, during normal
business hours. Such construction shall, from time to time, and for an
indefinite period, create higher than normal noise levels and make it difficult
for Landlord to keep the Building in a clean condition.

     2.7  Building Adjusted Rentable Area. The Adjusted Rentable Area of the
          -------------------------------                                   
entire Building in Item N, Basic Information of the Lease is amended to read
670,604 square feet in lieu of 666,7111 square feet.

3.   DEFINED TERMS.

     As used herein, capitalized terms shall have the meaning ascribed to them
in the Lease, unless expressly defined herein.

4.   LEASE IN FULL FORCE AND EFFECT.

     Except as hereby modified, the Lease remains unchanged and in full force
and effect.

                                       4.
<PAGE>
 
5.   SUCCESORS AND ASSIGNS.

     This Third Amendment shall bind and inure to the benefit of the parties
hereto and its respective successors and assigns.

6.   BROKERS.

     Tenant represents and warrants to Landlord that Tenant has had no dealings
with any broker, finder or similar person who is or might be entitled to a
commission or other fee in connection with this Third Amendment. Tenant shall
protect, defend and indemnify Landlord against, and hold Landlord harmless from,
any and all claims, demands, liability and costs (including reasonable
attorneys' fees), of any person, other than Landlord's Broker, who claims to
have dealt with Tenant in connection with the transaction contemplated by this
Third Amendment. Landlord shall protect, defend and indemnify Tenant against,
and hold Tenant harmless from, any and all claims, demands, liability and costs
(including reasonable attorneys' fees), of any person who claims to have dealt
with Landlord in connection with the transaction contemplated by this Third
Amendment.

7.   NO DEFAULT.

     Tenant represents and warrants that there are no defaults of Landlord under
the Lease or any existing conditions, which upon the giving of notice or the
lapse of time, or both, would constitute default under the Lease.

8.   OTHER INSTRUMENTS.

     Landlord and Tenant agree that they shall execute such other and further
documents as are necessary or convenient to effect the objectives of this Third
Amendment.

     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
and year above written.

                         "LANDLORD"     
                         ZORO, LLC, a California limited liability company 
                         

                         By:  /s/ Martin Zankel
                              --------------------------------------------- 
                         Its:     Managing Member
                              ---------------------------------------------


                         "TENANT"
                         FOCAL COMMUNICATIONS CORPORATION, a
                         Delaware corporation

                         By:  /s/ John Barnicle
                              ---------------------------------------------
                         Its:  E.V.P C.O.O
                               --------------------------------------------

                                       5.
<PAGE>
 
                                  EXHIBIT A-I

                    [PLAN OF TOWNSEND CENTER APPEARS HERE]

                                       6.

<PAGE>
 
                                                                 Exhibit 10.14


                                LEASE AGREEMENT

                                    between

                             INFOMART-Dallas, L.P.

                                      and

                   FOCAL COMMUNICATIONS CORPORATION OF TEXAS


                                  INFOMART(R)
                            The Technology Community
                             1950 Stemmons Freeway
                              Dallas, Texas 75207
                                  214-800-8000
<PAGE>
 
                                 LEASE AGREEMENT

                                    INFOMART
                            THE TECHNOLOGY COMMUNITY

- --------------------------------------------------------------------------------

THIS LEASE AGREEMENT (the "Lease") is made and entered into as of the 15th day
of December, 1998, by and between INFOMART-Dallas, L.P., a Texas limited
partnership ("Landlord"), whose address is 1950 Stemmons Freeway, Dallas, Texas
75207 and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, a Delaware corporation
("Tenant"), whose address is 200 LaSalle Street, Suite 800, Chicago, Illinois
60601. If there shall be more than one party executing this Lease as Tenant,
their obligations shall be joint and several. As used in this Lease, the terms
set forth in Article I of this Lease shall have the respective meanings
indicated in such Article.

Subject to all of the terms and conditions of this Lease, and in consideration
of the mutual covenants and obligations contained in this Lease, Landlord and
Tenant agree as follows:


                             ARTICLE 1 - DEFINITIONS
                             -----------------------

SECTION 1.1. BASE RENTAL shall mean Thirty-eight Thousand One Hundred Fifty-nine
and 11/100ths Dollars ($38,159.11) per month from the Commencement Date hereof
until June 30, 2009.

SECTION 1.2.  BASE YEAR shall mean 1999.

SECTION 1.3. THE "BUILDING" shall mean the information processing market center
located upon the real property (the "Property") described in Exhibit "A"
attached hereto and incorporated herein.

SECTION 1.4. BUILDING RULES shall mean rules and regulations adopted and altered
by Landlord from time to time for the safety, care and cleanliness of the Leased
Premises and the Building and for the preservation of good order therein, all of
which will be sent by Landlord to Tenant in writing and shall thereafter be
carried out and observed by Tenant. The initial Building Rules "Rules and
Regulations" are attached hereto as Exhibit "B". In the event of a conflict
between this Lease and such Rules and Regulations or the "INFOMART Policy
Statement" (as defined below), this Lease shall control for all purposes.
Landlord shall provide Tenant with a copy of all changes to the Rules and
Regulations and INFOMART Policy Statement which are approved, adopted, amended
or modified after the date this Lease is entered into. Landlord shall not
discriminate among the tenants of the Buildings regarding the enforcement of
Rules and Regulations and INFOMART Policy Statement.
<PAGE>
 
SECTION 1.5. COMMENCEMENT DATE shall mean the date on which Tenant commences
occupancy of the Leased Premises which shall be the date Tenant takes possession
of the Leased Premises for the purpose of equipping, furnishing, and improving
the Leased Premises. The term "Rental Commencement Date" (as defined below)
shall mean as defined in Section 1.21 hereof.

SECTION 1.6. COMMON AREAS shall mean those areas devoted to corridors, elevator
foyers, restrooms, mechanical rooms, janitorial closets, electrical and
telephone closets, vending areas, lobby areas, meeting rooms, auditoriums,
exhibit halls and other similar facilities provided for the common use or
benefit of tenants generally.

SECTION 1.7. INFOMART shall mean "INFOMART - The Technology Community" and shall
include that certain Building and Property as the same currently exists or as it
may from time to time hereafter be expanded or modified.

SECTION 1.8. INSURANCE COSTS shall mean all costs incurred by Landlord in
providing insurance, including but not limited to, property, liability and
casualty insurance, on the Building and Property, but excluding all insurance
costs which Tenant is required to provide under Section 5.3 hereof.

SECTION 1.9. LEASE TERM shall mean a term commencing on the Rental Commencement
Date and continuing for one hundred twenty (120) months.

SECTION 1.10. LEASED PREMISES shall mean Suite No. 6060 in the Building, as
outlined or marked in red on the floor plan of the Building attached to this
Lease as Exhibit "C".

SECTION 1.11. PERMITTED USE shall mean use for professional offices, and for the
installations, operation and maintenance of equipment and facilities in
connection with Tenant's telecommunications business and use for the display and
marketing of information processing and communications products and services and
for offices, storage and service areas incidental and related to such use.

SECTION 1.12.  RELOCATION SPACE Intentionally omitted.

SECTION 1.13. RENTABLE SQUARE FEET shall mean the Usable Square Feet of the
Leased Premises, together with an additional amount representing a portion of
the Common Areas, Service Areas and other non-tenant space on floors two (2)
through six (6) in the Building. For purposes of this Lease, the parties have
agreed that the Leased Premises shall be deemed to consist of 19,249 Rentable
Square Feet on floors two (2) through six (6) of the Building which shall be
deemed to consist of 1,056,200 Rentable Square Feet. However, both Landlord and
Tenant acknowledge that neither of these figures was calculated by measuring the
areas of actual Common Areas, Service Areas and other non-tenant spaces in the
Building and neither Landlord nor Tenant shall have a right to demand
remeasurement or recalculation of the Rentable Square Feet amounts for Floors
two (2) through six (6) or the Leased Premises, and regardless of the actual
size of the Building of Leased Premises, such areas shall be deemed to be the
measurements set forth in this Section 1.13.

                                       4
<PAGE>
 
SECTION 1.14. SECURITY DEPOSIT as used in Section 6.9 hereof shall mean
Thirty-six Thousand One Hundred Fifty-nine and 11/100ths Dollars ($38,159.11).

SECTION 1.15. SERVICE AREAS shall mean those areas within the outside walls used
for elevator mechanical rooms, building stairs, elevator shafts, flues, vents,
stacks, pipe shafts and vertical penetrations (but shall not include any such
areas for the exclusive use of a particular tenant).

SECTION 1.16. TAXES shall mean all taxes and assessments and governmental
charges, whether federal, state, county or municipal, and whether they be by
taxing districts or authorities presently taxing the Leased Premises or the
Property or any part thereof, or by others, subsequently created or otherwise,
and any other taxes and assessments attributable to the Property or its
operation but shall not include penalties for late or non-payment thereof.
Should taxes become payable over a number of years, only the portion of taxes
attributable to the Lease Term shall be included herein..

SECTION 1.17. TENANT'S PROPORTIONATE SHARE shall mean a fraction, the numerator
of which is the number of Rentable Square Feet comprising the Leased Premises,
and the denominator of which is the number of Rentable Square Feet comprising
floors two (2) through six (6) of the Building. Accordingly, the parties
acknowledge and agree that Tenant's Proportionate Share under this Lease is 1.18
percent.

SECTION 1.18. TRADE FIXTURES shall mean any and all signs placed by Tenant
within the Leased Premises pursuant to provisions hereof and any and all items
of property used by Tenant in the Leased Premises, including but not limited to
furniture and equipment; provided, however, that the term Trade Fixtures shall
not include any permanent leasehold improvements, including but not limited to
any floor, wall or ceiling coverings, any interior walls or partitions, any
lighting fixtures, track lights or any property which is a part of or associated
with any electrical, plumbing, or mechanical system, notwithstanding that the
same may have been installed within the Leased Premises. Not withstanding the
foregoing, Tenant's generator and telecommunications equipment, including, but
not limited to, Tenant's telephone switches, shall be deemed Trade Fixtures.

SECTION 1.19. USABLE SQUARE FEET shall mean the gross number of square feet
enclosed by the surface of the exterior glass walls, the midpoint of any walls
separating portions of the Leased Premises from those of adjacent tenants, the
slab penetration line of all walls separating the Leased Premises from Service
Areas and the corridor side of walls separating the Leased Premises from Common
Areas.

SECTION 1.20. UTILITY COSTS shall mean all costs incurred by Landlord in
providing electricity, gas, water and sewage disposal facilities to the
Building, including, without limitation, electricity used for heating, air
conditioning, operation of office machines and other equipment used on or about
the Building, and elevator and escalator service and lighting, but excluding all
such costs which Tenant may, from time to time, be obligated under the
provisions of Section 2.5 hereof to pay on a separately metered basis and
excluding such costs which other tenants of the Building may, from time to time,
be obligated to pay under the provisions of their leases.

                                       5
<PAGE>
 
SECTION 1.21. RENTAL COMMENCEMENT DATE shall mean the earlier of the date Tenant
receives a Certificate of Occupancy for the Leased Premises or September 1, 1999
provided that if the Commencement Date does not occur on or before February 1,
1999, the Rental Commencement Date shall be delayed one day for each day after
February 1, 1999 on which the Commencement Date occurs.


                                    ARTICLE 2
                                    ---------

SECTION 2.1. LEASED PREMISES AND TERM. Landlord does hereby lease, demise and
let to Tenant and Tenant does hereby lease and take from Landlord the Leased
Premises for a term beginning on the Commencement Date and continuing in full
force and effect for the Lease Term, unless this Lease is terminated earlier
pursuant to the provisions hereof. The Leased Premises are demised hereby
subject to all easements, restrictions, agreements of record, mortgages and
deeds of trust, and zoning and building laws. If Landlord is unable to deliver
possession of the Leased Premises to Tenant as of the Commencement Date
specified in Article 1 for any reason, including, without limitation, the
holding over of any tenant or occupant of the Leased Premises, then the term
"Commencement Date" shall mean such subsequent date upon which the Landlord is
able to deliver possession of the Leased Premises to Tenant, and such failure to
deliver possession of the Leased Premises on the Commencement Date specified in
Article 1 hereof shall not constitute a default by Landlord hereunder or render
Landlord liable for any loss or damage that may be incurred as a result of such
failure. If the Leased Premises are delivered to Tenant for occupancy on a date
prior to the Commencement Date specified in Article 1 hereof, Tenant agrees to
accept and occupy the Leased Premises on such date and the term "Commencement
Date" shall mean such date. Tenant shall commence to furnish, equip, and improve
the Leased Premises, in accordance with Section 4.2(a) hereof, on the
Commencement Date. Landlord shall have no obligation to furnish, equip or
improve the Leased Premises and Tenant has been afforded the right to inspect
the Leased Premises prior to the Commencement Date. By occupying the Leased
Premises, Tenant shall be deemed to have accepted the same and to have
acknowledged that the same comply fully with Landlord's covenants and
obligations hereunder. Notwithstanding the foregoing, to the extent that the
Leased Premises are not delivered to Tenant on or before April 1, 1999, Tenant
shall have the right to terminate this Lease by providing notice to Landlord
after such date.

Landlord acknowledges that Tenant's business to be conducted in the Lease
Premises requires the installation in the Leased Premises of certain
communications equipment by telecommunications customers of Tenant ("Customers")
in order for such Customers to interconnect with Tenant's terminal facilities.
Not withstanding anything contained in Section 4.7 of the Lease, Landlord agrees
that no consent shall be required for a co-location agreement between Tenant and
any such Customer for the purposes of permitting such a telecommunications
connection, so long as (i) such Customer agrees in writing to comply with all
obligations of Tenant under this Lease to the extent relating to the portion of
the Leased Premises in question, and (ii) each co-location agreement is in
writing and is consistent with the provisions of this Lease. Co-location shall
not be deemed under any circumstances to be a sublet or assignment of the Leased
Premises.

                                       6
<PAGE>
 
SECTION 2.2. USE. The Leased Premises may be used and occupied by Tenant solely
for the Permitted Use and for no other purpose. Warehousing and on-site delivery
to customers is prohibited in the Building or any part thereof. Payment for
products or services that are of a retail sales nature are prohibited (provided,
however, that payment or partial payment for orders taken at the Leased Premises
for future delivery to a buyer will be allowed if it is within the Tenant's
normal business practice and is not of a retail sales nature, it being the
intention hereof to permit payments or partial payments intended to bind an
order for future delivery without in any way qualifying or circumventing the
prohibition within the Building against retail sales). Tenant warrants and
represents to Landlord that it is a producer of hardware, software or services
utilizing information processing equipment (and, if the Tenant's business
includes the resale of products or services, Tenant warrants and represents that
it adds to or enhances the value of such products or services). Tenant shall not
use or allow the Leased Premises to be used in any manner which obstructs or
interferes with the rights of other tenants of the Building or injures or annoys
such tenants, and Tenant shall not cause, maintain or permit any nuisance in, on
or about the Leased Premises or the Building, or permit or suffer to be
committed any defacement, injury or waste to, in, on, or about the Leased
Premises or the Building.

         SECTION 2.3. BASE RENTAL. Tenant agrees to pay the Base Rental to
Landlord for each month during the Lease Term as herein provided. Base Rental
for the first month of the Lease Term shall be due and payable in advance on the
Rental Commencement Date, and Base Rental for each and every month thereafter
during the Lease Term shall be due and payable in advance on the first day of
the month. If the Rental Commencement Date is a day other than the first day of
a calendar month or in the event this Lease terminates on other than the last
day of a calendar month, then Base Rental for such month or months shall be
prorated and the installment or installments so prorated shall be paid in
advance. In the event that Tenant fails to make any payment of Base Rental or
any other sums due hereunder on or before the date any such payment becomes due
and payable, the Tenant shall also be obligated to pay interest on such past due
amounts at a rate equal to the lesser of the prime rate plus four percent (4%)
per annum or the highest rate permitted by law, such interest being in addition
to and cumulative of any other rights and remedies which Landlord may have
hereunder with regard to the failure of Tenant to make any payment of Base
Rental or any other sum due hereunder. As used herein, the phrase "prime rate"
means, on any day, the rate of interest per annum then most recently established
by NationsBank of Texas, N.A. as its general reference rate of interest, taking
into account such factors as such bank may deem appropriate, it being understood
that such rate is not necessarily the lowest or best rate actually charged to
any customer of such bank or a favored rate.

SECTION 2.4. TENANT'S PROPORTIONATE SHARE OF TAXES, INSURANCE COSTS AND UTILITY
COSTS. In addition to the payment of Base Rental, Tenant shall pay to Landlord
Tenant's Proportionate Share of Utility Costs, Insurance Costs and Taxes, in
accordance with the following provisions:

(a)      Tenant shall pay to Landlord, either in the form of a lump sum payment
         due and payable upon demand by Landlord or on a monthly basis
         contemporaneously with the payment of Base Rental, as Landlord may
         elect, (i) an amount reasonably estimated by Landlord to be Tenant's
         Proportionate Share of all Utility Costs for each calendar year or
         portion thereof during the Lease Term, (ii) an amount reasonably
         estimated by Landlord to be

                                       7
<PAGE>
 
         Tenant's Proportionate Share of all Insurance Costs for each calendar
         year or portion thereof during the Lease Term and (iii) an amount
         reasonably estimated by Landlord to be Tenant's Proportionate Share of
         the amount, if any, by which Taxes for each calendar year or portion
         thereof during the term of this Lease exceed Taxes for the Base Year.

(b)      If at any time Landlord shall have reasonable grounds to believe that
         actual Utility Costs, Insurance Costs or Taxes incurred will vary from
         such estimates, then Landlord reserves the right to revise such
         estimates accordingly. Upon any such revision, Landlord shall notify
         Tenant and Landlord may, at Landlord's election, either (i) require
         Tenant to make a lump sum payment to Landlord reflecting such revised
         estimate or (ii) require that the monthly payments due and payable to
         Landlord by Tenant under this Section be revised to an amount which
         will amortize such revised estimate over the remainder of the calendar
         year in which any such revision is made by Landlord.

(c)      As soon as reasonably practical following the end of any calendar year
         during which such payments were made by Tenant, Landlord shall deliver
         to Tenant a statement reconciling the amounts paid by Tenant for such
         year against the actual charges for such items and a lump sum payment
         (or credit against the next succeeding installments of Base Rental, if
         any, in case of amounts owed by Landlord to Tenant) shall be made from
         Tenant to Landlord or from Landlord to Tenant, as the case may be, so
         that Tenant shall have paid to Landlord only Tenant's Proportionate
         Share of (i) Utility Costs for the previous calendar year, (ii),
         Insurance Costs for the previous calendar year, and (iii) the amount,
         if any, by which Taxes for the previous calendar year exceed Taxes for
         the Base Year and no more, which obligation to make such reconciliation
         payment shall survive the termination of the Lease. Tenant shall have
         the right to audit copies of paid invoices for Common Area Utility
         Costs, Taxes, and Insurance for the then previous calendar year within
         the Lease Term; but Tenant shall not have the right to audit Landlord's
         records for any previous calendar year within the Lease Term or for any
         year prior to the Commencement Date of this Lease. If Tenant's audit
         reveals Landlord's statement for such expenses have been overstated by
         more than five percent (5%), then Tenant shall submit a copy of its
         audit to Landlord. If Landlord disagrees with the results of Tenant's
         audit, Landlord shall submit such audit, and Landlord's records
         relative to such expenses, to Landlord's independent auditors for their
         review. If Landlord or Landlord's auditors agree that such expenses
         have been overstated by more than five percent (5%), then Landlord
         shall pay all reasonable costs and expenses of such audit, and, in any
         event, shall, within thirty (30) days after the completion of
         Landlord's review of such audit, reimburse Tenant for any and all
         overages. If the audit conducted by Landlord or Tenant reveals that
         Landlord's statement for such expenses was correct, then Tenant shall
         pay all reasonable costs and expenses incurred by Landlord relative to
         such audit. Further, if either audit reveals that Landlord undercharged
         Tenant relative to these expenses, then Tenant shall, within thirty
         (30) days after the completion of such audit, reimburse Landlord for
         any undercharges. Tenant shall not have the right to audit Landlord's
         records relative to such expenses more than once in any calendar year.

(d)      If the Commencement Date is a day other than the first day of a
         calendar month or if this Lease terminates on other than the last day
         of a calendar month, then the amounts due and owing by Tenant to
         Landlord under this Section shall be prorated accordingly.

                                       8
<PAGE>
 
SECTION 2.5. SEPARATELY METERED UTILITIES AND UTILITY USAGE. Tenant shall pay
upon demand or receipt of an invoice all amounts due and owing with respect to
utilities furnished to the Leased Premises which may, from time to time, be
separately measured and charged to the Tenant by Landlord or any public utility
as may furnish such utilities to the Leased Premises. In the event that any
electrical services required or used in the Leased Premises shall exceed seven
(7) watts per square foot of Usable Square Feet within the Leased Premises.
Tenant shall cause the installation of all facilities necessary to separately
meter electrical usage within the Leased Premises and/or cause the installation
of such riser or risers, wiring, transformer, or electrical panels as are
required to meet Tenant's excess electrical requirements and Tenant shall pay to
Landlord or, at the election of Landlord, to the applicable public utility,
promptly upon receiving any invoice, all charges for electrical usage within the
Leased Premises in excess of seven (7) watts per square foot of Usable Square
Feet within the Leased Premises; which payment, if any, shall be in addition to
sums required to be paid by Tenant pursuant to Section 2.4 above. Landlord
covenants that (a) there are currently 7 watts of electricity per square foot of
Usable Square Feet serving the floor upon which the Leased Premises are located
and (b) there are currently at least 28 watts of electricity per square foot of
Usable Square Feet available to Tenant's use in the Leased Premises. To the
extent that Tenant requests the ability to upgrade the electrical service to the
Leased Premises to an amount in excess of 28 watts of electricity per square
foot of Usable Square Feet of the Leased Premises, Tenant shall have the right,
at its sole cost, to upgrade the Building's electrical system for the floor on
which the Leased Premises are located in order to meet such excess capacity
request. In such event, Landlord shall have the right to review Tenant's plans
and specifications for such upgrade and Landlord shall have the right to
supervise Tenant's installations necessary to upgrade the electrical service to
the Leased Premises. Tenant shall promptly reimburse Landlord for Landlord's
documented actual out-of-pocket costs for such supervision. Notwithstanding the
foregoing, Landlord may refuse to install, and may withhold consent for Tenant's
installation of, any riser, wiring, transformer, or electrical panel if, in
Landlord's sole reasonable judgment (exercised in good faith), the same would
cause permanent damage or injury to the Building or the Leased Premises or cause
or create a dangerous or hazardous condition or entail excessive or unreasonable
alterations, repairs, or expense or interfere with or disturb other tenants or
occupants of the Building. In no event shall Landlord incur any liability or
obligation with respect to Landlord's refusal to install, or withholding consent
for Tenant's installation of, any such additional electrical facilities or
equipment.

SECTION 2.6. ADDITIONAL RENT; PAYMENTS. All sums of money due and payable by
Tenant to Landlord under the term of this Lease in addition to the Base Rental
shall constitute additional rent hereunder. Landlord shall have the same
remedies for default in the payment of additional rent as are available to
Landlord in the case of a default in the payment of Base Rental. All rent shall
be payable at Landlord's address as provided herein (or at such other address as
may be designated by Landlord from time to time). Tenant agrees to pay all rent
under this Lease at the times and in the manner herein provided, without demand,
counterclaim or set-off, except as set forth herein.


                                       9
<PAGE>
 
                                    ARTICLE 3
                                    ---------

SECTION 3.1. UTILITIES. Landlord shall use reasonable efforts to cause public
utilities to furnish electricity to the Leased Premises and water to the
Building to the extent and in such manner as is reasonably deemed by Landlord to
be standard for the Building.

SECTION 3.2. SERVICES TO BE FURNISHED BY LANDLORD TO TENANT. Landlord shall
furnish or cause to be furnished during the Lease Term:

(a)      Central heating and air conditioning to the Leased Premises and
         enclosed public areas of the Building in season;

(b)      Non-exclusive passenger escalator and elevator service and
         non-exclusive freight elevator service;

(c)      Electric lighting service for all public areas of the Building;

(d)      Janitorial service for the corridors and other public areas of the
         Building; and

(e)      Public toilets and restrooms and public drinking fountains;

Such services shall be provided during normal business hours, reasonably
established by Landlord, at such locations, in such manner and to the extent
deemed reasonable by Landlord, to be adequate for the use and occupancy of the
Building, with due regard for the prudent control of energy.

SECTION 3.3. LANDLORD'S FAILURE TO PROVIDE UTILITIES OR SERVICES. Failure by
Landlord to any extent to furnish or cause to be furnished the utilities or
services described in Section 3.1 and 3.2, or any cessation or interruption
thereof, resulting from any cause, including without limitation, mechanical
breakdown, overhaul or repair of equipment, strikes, riots, acts of God,
shortages of labor or material, compliance by Landlord with any voluntary or
similar governmental or business guidelines, governmental laws, regulations or
restrictions, or any other similar causes shall not render the Landlord liable
in any respect for damages to either person or property, for any economic loss
or other consequential damages incurred by Tenant as a result thereof, be
construed as an eviction of Tenant, result in an abatement of rent, or relieve
Tenant from its obligation to perform or observe any covenant or agreement
contained in this Lease. Notwithstanding the foregoing, in the event that the
Leased Premises are rendered untenantable due to the failure or interruption of
the utilities or services described in Sections 3.1 and 3.2 hereof (for any
reason other than Tenant's fault or neglect) for ten (10) consecutive days and
Tenant does not, in fact, use the applicable portion of the Leased Premises
during such period of such untenantability, Base Rental hereunder shall abate
with respect to that portion of the Leased Premises so rendered untenantable
from the business day Tenant first ceases to use that portion of the Leased
Premises to the earlier to occur of (i) the date Tenant again commences to use
that portion of the Leased Premises or (ii) the date on which that portion of
the Leased Premises is again rendered tenantable.

                                       10
<PAGE>
 
SECTION 3.4. PEACEFUL ENJOYMENT. Subject to the other terms of this Lease,
Landlord covenants that Tenant shall, and may peacefully have, hold and enjoy
the Leased Premises for the Lease Term free of any claims by any party claiming
by, through or under Landlord, provided that Tenant pays the rent to be paid by
Tenant under this Lease and performs all of Tenant's covenants and agreements
herein provided after notice and cure periods, if any.

                                    ARTICLE 4
                                    ---------

SECTION 4.1. OPERATION. If the Leased Premises front on the atrium within the
Building, at all other times during all normal business hours of the Building,
Tenant shall not abandon the Lease Premises and shall ensure that the lights
remain on in the Leased Premises during normal business hours. If the Leased
Premises front on the atrium of the Building, the failure of Tenant to
substantially complete its improvements at the Leased Premises by December 31,
1999, with adequate staff, shall, at the option of Landlord, be an event of
default hereunder.

SECTION 4.2.  ALTERATIONS, IMPROVEMENTS AND ADDITIONS.

(a)      Tenant shall furnish, equip and improve the Leased Premises with
         partitions, lighting fixtures, wall and floor coverings, paintings and
         other interior decoration suitable for a trade mart and of a quality
         and design consistent with the standards generally observed by
         Landlord. Prior to the commencement of any such work, Tenant shall
         submit to Landlord for its written approval, detailed plans and
         specifications providing for the initial furnishing, equipping and
         improving of the Leased Premises. Two (2) complete sets of final
         working drawings and  specifications  of materials  relating to all
         improvements ("Improvements") that Tenant desires to be installed in
         the Leased Premises shall be submitted to Landlord no later than thirty
         (30) days prior to the date specified in Section 1.5 hereof. Such
         drawings and the specifications of materials shall be subject to
         approval by Landlord which approval shall not be unreasonably withheld.
         Any delay occasioned as a result of Landlord's disapproval of Tenant's
         plans and specifications shall not delay the Commencement Date under
         this Lease except as set forth herein. Upon the approval of the plans
         and specifications by Landlord, Tenant shall commence to equip,
         furnish, and improve the Leased Premises, and shall diligently and
         continuously prosecute such work to substantial completion on or before
         December 31, 1999. The failure of Tenant to substantially complete such
         work on or before the date specified in the preceding sentence shall,
         at the option of Landlord, be an event of default hereunder. Any
         further alterations, improvements or additions to the Leased Premises
         (including constructing partitions, installing light fixtures or
         painting or changing the color of any painted surface or the color type
         of any wall, floor or ceiling covering) shall likewise require
         Landlord's prior written approval. In the event that Landlord and
         Tenant cannot agree on Tenant's plans and specifications within sixty
         (60) days after submission thereof to Landlord, Tenant shall have the
         right to terminate this Lease by providing written notice to Landlord
         within sixty-five (65) days after submission of plans to Landlord.

         In addition, but provided no event of default has occurred and is
         continuing under the Lease, Tenant shall have the right at any time
         during the Lease Term to upgrade the Building's and/or Tenant's
         HVAC/chilled water capacity, or install its own HVAC system

                                       11
<PAGE>
 
         at its sole expense with Landlord's prior written approval.

(b)      Any and all furnishing, equipping and improving of or other alteration
         or addition to the Leased Premises shall be:

         (i)      made at Tenant's sole cost, risk and expense;

         (ii)     performed in a prompt, good and workmanlike manner with labor
                  and materials of such quality as Landlord may reasonably
                  require;

         (iii)    constructed in accordance with all plans and specifications
                  approved in writing by Landlord prior to the commencement of
                  any such work, provided, however, that Landlord shall have no
                  responsibility with respect to, nor any liability as a result
                  of, defects or deficiencies therein;

         (iv)     prosecuted diligently and continuously to completion and in
                  such manner so as to minimize interference with the normal
                  business operations of other tenants in the Building, the
                  performance of Landlord's obligations under this Lease or any
                  mortgage or ground lease covering or affecting all or any part
                  of the Building or the Property, and any work being done by
                  contractors engaged by Landlord with respect to or in
                  connection with the Building; and

         (v)      performed by contractors approved in writing by Landlord, and
                  if requested by Landlord any such contractor and all work to
                  be performed by such contractor shall be fully bonded with
                  companies and in amounts acceptable to Landlord in its sole
                  discretion.

(c)      Any and all alterations, improvements and additions to the Leased
         Premises (except for Trade Fixtures as specified in Section 4.4 hereof)
         shall constitute a part of the Leased Premises, and shall be owned by
         and become the property of Landlord effective as of the termination of
         this Lease. Tenant shall have no (and hereby waives all) rights to
         payment or compensation for any such alteration, improvement or
         addition to the Leased Premises.

SECTION 4.3. MAINTENANCE AND REPAIRS. Tenant shall maintain the Leased Premises,
all plate glass and all Trade Fixtures and other improvements situated therein
in first class, clean, and safe condition. Tenant shall repair or replace any
damage to the Building, or any part thereof, caused by Tenant or Tenant's
agents, employees, customers or invitees. All such repair or replacement shall
be performed in accordance with the conditions set forth in Section 4.2.(b) (i),
(ii), (iii), (iv) and (v).

SECTION 4.4. TRADE FIXTURES. Landlord and Tenant agree that all Trade Fixtures
installed in the Leased Premises shall be and remain the property of Tenant and,
so long as Tenant is not in default hereunder, may be removed by Tenant prior to
or upon the expiration of the Lease Term. Tenant shall repair any damage caused
by such removal and restore the Leased Premises to such condition as existed
prior to the installation of such Trade Fixtures. Any such repair and
restoration shall be performed in accordance with the conditions set forth in
Section

                                       12
<PAGE>
 
4.2(b) (i), (ii), (iii), (iv) or (v). Any Trade Fixtures which are not removed
from the Leased Premises upon cessation of occupancy by Tenant and upon prior
written notice to Tenant's last known address shall become the property of
Landlord. Tenant shall have no (and hereby waives all) rights to payment or
compensation for any such item.

SECTION 4.5.  LAWS AND REGULATIONS; BUILDING RULES; INFOMART POLICY STATEMENT.

(a)      Tenant shall comply with all laws, ordinances, rules and regulations of
         any governmental authority relating to the use, condition or occupancy
         of the Leased Premises or the Building, including the furnishing,
         equipping and improving thereof.

(b)      Tenant shall, and shall cause its employees, agents, customers and
         invitees to comply with the Building Rules adopted and altered by
         Landlord from time to time. All changes in such rules will be sent by
         Landlord to Tenant in writing.

(c)      Landlord has prepared a policy  statement  with respect to the
         operation of the Building  attached  hereto as  Exhibit  "D" which may
         from time to time be  amended,  revised  or  supplemental  at
         Landlord's  sole discretion (the "INFOMART  Policy  Statement"). Tenant
         shall be responsible for conducting its operations within the Leased
         Premises  and the  Building in  compliance  with the  INFOMART  Policy
         Statement.  The failure of the Landlord to successfully  enforce any
         provisions of the INFOMART Policy  Statement  against Tenant,  or
         against any other  tenant or occupant of the  Building,  shall not be
         deemed to be a waiver of the  requirements  of the INFOMART  Policy
         Statement.  Landlord  shall not be  responsible  to Tenant for
         nonperformance  by any  other  tenant  or  occupant  of the  Building
         of any of the  requirements  of the Building Rules or the INFOMART
         Policy  Statement;  and Tenant shall be liable for all injuries or
         damages sustained by Landlord or Landlord's  agents or by other
         tenants,  occupants,  or invitees of the Building arising  by  reason
         of any  breach of the  requirements  of the  Building  Rules or the
         INFOMART  Policy Statement by Tenant or Tenant's agents, employees or
         invitees.

SECTION 4.6. LANDLORD'S ACCESS. Landlord and its representatives, agents,
officers and contractors shall have the right to enter upon the Leased Premises
at any reasonable time for any reasonable purpose, at any time for any
emergency, and if a default by Tenant exists hereunder, at any time to show the
Leased Premises to prospective tenants. Landlord agrees that to the extent
possible it will not unreasonably interfere with the conduct of Tenant's
business in the exercise of its rights hereunder.

SECTION 4.7. ASSIGNMENT AND SUBLETTING BY TENANT.

(a)      Tenant shall not, by operation of law or otherwise, (i) assign,
         transfer, mortgage, pledge, hypothecate or otherwise encumber this
         Lease, the Leased Premises or any interest therein, (ii) grant any
         concession or license within the Leased Premises, (iii) grant or
         transfer any management privileges or rights with respect to the Leased
         Premises, (iv) sublet all or any part of the Leased Premises or any
         right or privilege appurtenant to the

                                       13
<PAGE>
 
         Leased Premises, or (v) permit any other party to occupy or use all or
         any part of the Leased Premises except for as provided in Section 2.2.
         If Tenant is other than an individual person, any conveyance,
         assignment or transfer of any interest in Tenant shall be deemed to
         constitute a transfer or assignment prohibited by the immediately
         preceding sentence. No consent granted by Landlord to any transfer,
         assignment or other transaction prohibited by this Section shall
         release Tenant from any of Tenant's obligations under this Lease or be
         deemed to constitute a consent to any subsequent assignment,
         subletting, occupancy or use of the Leased Premises by another person.
         Subject to the foregoing, the rights and obligations of the parties to
         this Lease shall inure to the benefit of and be binding upon their
         respective successors, assigns, heirs and legal representatives. Any
         attempted assignment or sublease by Tenant in violation of the terms
         and covenants of this paragraph shall be void and constitute a default
         by Tenant.

(b)      One half of all net cash or other net proceeds of any assignment, sale
         or sublease of Tenant's interest in this Lease and/or the Leased
         Premises (not including Trade Fixtures), whether consented to by
         Landlord or not, shall be paid to Landlord notwithstanding the fact
         that such proceeds exceed the rents called for hereunder, unless
         Landlord agrees to the contrary in writing, and Tenant hereby assigns
         all rights it might have or ever acquire in any such proceeds to
         Landlord.  This covenant and assignment shall benefit Landlord and its
         successors in ownership of the Building and shall bind Tenant, Tenant's
         heirs, executors, administrators, personal representatives, successors
         and assigns.  Any assignee, sublessee, or purchaser of Tenant's
         interest in this Lease (all such assignees, sublessees or purchasers
         being hereinafter referred to as "Successors"), by occupying the Leased
         Premises and/or assuming Tenant's obligations hereunder, shall be
         deemed to have assumed liability to Landlord for all amounts paid to
         persons other than Landlord by such Successor in consideration of any
         such sale, assignment or subletting, in violation of the provision
         hereof.  The acceptance by Landlord of any rent from any sublessee or
         assignee of Tenant shall not constitute Landlord's consent to such
         assignment or sublease. Notwithstanding the foregoing, Tenant may, upon
         written notice to Landlord of the identity of the Affiliate, assign or
         sublet its interest under this Lease in the Leased Premises to an
         "Affiliate" of Tenant, provided (i) that such assignee or subtenant
         assumes in full, the obligations of Tenant under this Lease, (ii) such
         Affiliate's business operations are consistent with the Permitted Use,
         and (iii) such sublease or assignment shall not operate to release
         Tenant from its obligations under this Lease. As used herein, the term
         "Affiliate" shall be a corporation which controls, is controlled by, or
         is under common control with Tenant, control to be determined, for
         purposes hereof, by the ownership of in excess of fifty percent (50%)
         of the issued and outstanding voting stock of such entity.  In
         addition, the term "Affiliate" shall include any entity (a) resulting
         from a merger or consolidation with Tenant, (b) any entity succeeding
         to substantially all the business and assets of Tenant at the Leased
         Premises, (c) any subsidiary, spin-off, affiliate or parent of Tenant,
         or (d) any entity resulting from the reorganization of Tenant outside
         of a bankruptcy organization.  In the case of sublease or assignment to
         an Affiliate, Landlord shall not have any right to share in any excess
         rents.

                                       14
<PAGE>
 
SECTION 4.8. LIGHT, AIR AND VIEW. Neither the diminution nor the shutting off of
any natural light, air, or view nor any other effect on the Leased Premises by
any structure or condition now or hereafter existing on property adjacent to the
Building shall affect this Lease, abate rent, or otherwise impose any liability
on Landlord.

SECTION 4.9. TAXES. Tenant shall pay all ad valorem and similar taxes or
assessments levied upon or applicable to any of Tenant's Trade Fixtures or any
other improvements, equipment, fixtures, furniture or other property situated in
the Leased Premises and all license and other fees or charge imposed on the
business conducted by Tenant on the Leased Premises. Upon request by Landlord,
Tenant will furnish Landlord annually with official tax receipts and other
official receipts showing payment of such taxes, assessments, fees and charges.
If Landlord shall be required to pay a higher ad valorem tax as a result of
Tenant's leasehold improvements, then Tenant shall pay to Landlord, upon demand,
the amount of such increase in ad valorem taxes.

SECTION 4.10. LIENS. Tenant shall not place or permit to be placed any lien,
affidavit, charge or order upon INFOMART, the Building or the Leased Premises or
any part thereof or any interest therein. In the event that any such lien,
affidavit, charge or order attaches, regardless of the validity or
enforceability thereof, Tenant shall promptly cause the same to be discharged of
record by payment or by the filing of a statutory bond in lieu of payment within
ten (10) days of Tenant's receipt of notice of such lien. In the event any such
lien is attached to the INFOMART, the Leased Premises or the Building, then in
addition to any other right or remedy of Landlord, Landlord may but shall not be
obligated to discharge the same. Any amount paid by Landlord for any of the
aforesaid purposes shall be paid by the Tenant to Landlord on demand as
additional rent.

SECTION 4.11. SUBORDINATION TO MORTGAGES AND LEASES. This Lease shall be subject
and subordinate at all times to (a) all ground or underlying leases now existing
or which may hereinafter be executed affecting the Building, the Leased Premises
and/or the Property (b) the lien or liens of all mortgages and deeds of trust in
any amount or amounts whatsoever now or hereafter placed on the Building, the
Leased Premises and/or the Property or Landlord's interest or estate therein or
on or against such ground or underlying leases and (c) all renewals,
modifications, consolidations, replacements and extensions thereof. The
subordinations set forth herein shall be self-operative and effective without
the necessity of execution of any further instruments by any party; provided,
however, Tenant shall execute and deliver upon demand by Landlord any
instruments, releases or other documents requested by any lessor or mortgager
for the purpose of confirming the provisions hereof or further subjecting and
subordinating this Lease to any such ground lease, mortgage or deed of trust. In
the event of the enforcement by the trustee or the beneficiary under any such
mortgage or deed of trust, of the remedies provided for by law or by such
mortgage or deed of trust, upon request of any person or party succeeding to the
interest of Landlord as a result of such enforcement, Tenant will automatically
become the Tenant of such successor in interest without change in the terms or
provisions of this Lease; provided, however, that such successor in interest
shall not be bound by (i) any payment of rent or additional rent for more than
one month in advance except prepayments actually delivered to such successor in
the nature of security for the performance by Tenant of its obligations under
this Lease, (ii) any payment of the security deposit or any other

                                       15
<PAGE>
 
deposit unless such security deposit or other deposit has actually been
delivered to such successor or (iii) any amendment or modification of this Lease
made without the written consent of such trustee or such beneficiary or such
successor in interest, and Tenant shall execute and deliver an instrument or
instruments confirming the attornment and other agreements provided for herein.
Further, notwithstanding anything contained in this Lease to the contrary, in
the event of any default by Landlord in the performance of its covenants or
obligations hereunder which would give Tenant the right to terminate this Lease,
Tenant shall not exercise such right unless and until (i) Tenant gives written
notice of such default (which notice shall specify the exact nature of said
default and the steps necessary to cure same) to the holder of any mortgage or
deed of trust encumbering the Building, the Leased Premises and/or the Property
who has theretofore notified Tenant in writing of its interest and the address
to which notices are to be sent, and (ii) such holder, upon becoming entitled to
do so, through foreclosure of its lien, or accepting a deed in lieu of
foreclosure, or otherwise, fails to cure or cause to be cured such default
within thirty (30) days from the later of the receipt of such notice from Tenant
or its becoming entitled to do so, or, if such default relates to a condition
which cannot reasonably be cured within such period, such holder commences to
cure within such period and thereafter diligently prosecutes the completion of
such cure. Landlord shall, in the event that a mortgage or deed of trust lien is
placed upon the Property and/or the Building, utilize reasonable efforts to
obtain a non-disturbance agreement from the holder thereof with respect to
Tenant's leasehold interests under the Lease, which non-disturbance agreement
shall be deemed to be sufficient if in form and content identical to the form of
Subordination, Non-Disturbance and Attornment Agreement attached hereto as
Exhibit "L" and incorporated herein by reference for all purposes.

SECTION 4.12. CERTIFICATES. At any time and from time to time during the Lease
Term, within ten (10) days after written request by Landlord, Tenant will
execute, acknowledge and deliver to Landlord and any other persons specified by
Landlord a certificate certifying (to the extent of being true and accurate) (i)
that this Lease is in full force and effect, (ii) the date and nature of each
modification to this Lease , (iii) the date to which rental and other sums
payable to this Lease have been paid, (iv) that Tenant is not aware of any
default under this Lease which has not been cured, except such defaults as may
be specified in said certificate, and (v) such other matters as may be
reasonably requested by Landlord. Any such certificate may be relied upon by
Landlord and by any other person to whom it is delivered for such purpose.

SECTION 4.13. LIMITATION ON WEIGHT. Tenant shall not permit upon the floor of
the Leased Premises any weight exceeding seventy-five (75) pounds per square
foot of floor area.

                                    ARTICLE 5
                                    ---------

SECTION 5.1. CONDEMNATION. If all of the Building, or the whole or substantially
the whole of the Property (including surface and covered parking associated with
the Building) or the Leased Premises should be taken for any public or
quasi-public use, by right of eminent domain or otherwise or should be sold in
lieu of condemnation, then this Lease shall terminate as of the date when
physical possession of the Building, or the Leased Premises, or the Property is
taken by the condemning authority. If less than the whole of the Building or
less than the whole

                                       16
<PAGE>
 
 or substantially the whole of the Property (including surface and covered
parking associated therewith) or the Leased Premises is thus taken or sold,
Landlord (whether or not the Leased Premises are affected thereby) may terminate
this Lease by giving written notice thereof to Tenant; in which event this Lease
shall terminate as of the date when physical possession of such portion of the
Building, Property, or Leased Premises is taken by the condemning authority. If
this Lease is not so terminated upon any such taking or sale, the Base Rental
payable hereunder shall be diminished by a prorata amount representing that
portion of the Base Rental allocable to the portion, if any, of the Leased
Premises subject to such taking, and Landlord shall, to the extent Landlord
deems feasible, restore the Building shell to substantially their former
condition, but such work shall not exceed the scope of the work done by landlord
in originally constructing the Building, nor shall Landlord in any event be
required to spend for such work an amount in excess of the amount received by
Landlord as compensation for such taking. All amounts awarded upon a taking of
any part or all of the Property, the Building or the Leased Premises shall
belong to Landlord, and Tenant shall not be entitled to and expressly waives all
claim to any such compensation.

SECTION 5.2. CASUALTY DAMAGE. If the Leased Premises or any part thereof shall
be damaged by fire or other casualty, Tenant shall give prompt written notice
thereof to Landlord. In case the Building shall be so damaged that substantial
alteration or reconstruction of the Building shall, in Landlord's sole
discretion, be required (whether or not the Leased Premises shall have been
damaged by such casualty) or in the event any mortgagee of Landlord's should
require that the insurance proceeds payable as a result of a casualty be applied
to the payment of the mortgage debt or in the event of any material uninsured
loss to the Building, Landlord may, at its option, terminate this Lease by
notifying Tenant in writing of such termination within ninety (90) days after
the date of such casualty. If Landlord does not thus elect to terminate this
Lease, Landlord shall commence and proceed with reasonable diligence to restore
the Building shell; except that Landlord's obligation to restore shall not
require Landlord to spend for such work an amount in excess of the insurance
proceeds actually received by Landlord as a result of the casualty. When the
repairs described in the preceding sentence have been completed by Landlord,
Tenant shall restore all improvement necessary to permit Tenant's re-occupancy
of the Leased Premises, and the restoration of Tenant furniture and equipment.
All cost and expense of reconstructing the Leased Premises shall be borne by
Tenant. Landlord shall not be liable for any inconvenience or annoyance to
Tenant or injury to the business of Tenant resulting in any way from such damage
or the repair thereof, except that, subject to the provisions of the next
sentence, Landlord shall allow Tenant a fair diminution of rent during the time
and to the extent the Leased Premises are unfit for occupancy and are
unoccupied. If the Leased Premises or any other portion of the Building be
damaged by fire or other casualty resulting from the fault or negligence of
Tenant or any Tenant's agents, employees, or invitees, the rent hereunder shall
not be diminished during the repair and restoration of the Building and Tenant
shall be liable to Landlord for rent and for the cost of repair and restoration
of the Building caused thereby to the extent such cost and expense is not
covered by insurance proceeds actually received by Landlord. Notwithstanding the
foregoing, in the event that it is estimated that Landlord will need more than
one hundred eighty (180) days to repair the damage caused by such casualty,
Tenant shall have the right to terminate this Leased by providing written notice
to Landlord within five (5) days of Landlord's notice to Tenant.

                                       17
<PAGE>
 
SECTION 5.3. INSURANCE.

(a)      Landlord shall not be obligated to insure any of Tenant's goods, Trade
         Fixtures, furniture or any other property placed in or incorporated in
         the Leased Premises or the Building. Landlord shall maintain insurance
         during the Lease Term as required by then current lender.

(b)      Tenant shall, at its sole cost and expense, procure and maintain during
         the Lease Term, commercial general liability insurance (such insurance
         to afford minimum protection of not less than $5,000,000.00 combined
         single limit coverage of bodily injury, property damage or combination
         thereof), property insurance with respect to Tenant's personal
         property, inventory and leasehold improvements written on an all "All
         Risk" basis for full replacement cost, worker's compensation and
         employer's liability insurance, comprehensive catastrophe liability
         insurance and such other insurance as Landlord may, from time to time,
         reasonably require. In addition, Tenant agrees to obtain a fire legal
         liability endorsement or other coverage satisfactory to Landlord which
         removes the "owned, rented or occupied" property exclusion from
         Tenant's liability policy. All such insurance shall be maintained by
         companies on forms and in amounts approved by Landlord.

(c)      In the event that Tenant fails to take out or maintain any policy
         required by this Article to be maintained by Tenant, such failure shall
         be a defense to any claim asserted by Tenant against Landlord by reason
         of any loss sustained by Tenant that would have been covered by such
         policy.

(d)      All policies of insurance required to be maintained by Tenant shall
         provide that the Landlord shall be given at least thirty (30) days
         prior written notice of any cancellation or non-renewal of any such
         policy. A duplicate original of each such policy or a duly executed
         certificate of insurance with respect to each such policy shall be
         deposited with Landlord by Tenant on or before the Commencement Date,
         and a duplicate original of each subsequent policy or a duly executed
         certificate of insurance with respect to each subsequent policy shall
         be deposited with Landlord at least fifteen (15) days prior to the
         expiration of the policy then in force.

(e)      Tenant shall not do or permit anything to be done in the Building or
         about the Leased Premises nor bring nor keep nor permit anything to be
         brought to or kept therein, which will in any way increase the existing
         rate of or affect any fire or other insurance which Landlord carries
         upon any part of the Building or any of its contents, or cause a
         cancellation or invalidation of any such insurance. If the annual
         premiums to be paid by Landlord with respect to any insurance obtained
         by Landlord covering any part of the Building or any of its contents
         shall exceed the standard rates because of Tenant's operations, or
         contents of the Leased Premises or because improvements with respect to
         the Leased Premises result in extra-hazardous exposure, Landlord shall
         have the further right, exercisable in Landlord's sole discretion, to
         terminate this Lease by giving written notice of such election to
         Tenant.

                                       18
<PAGE>
 
(f)      Subject to the conditions hereinafter specified in this Subsection (f)
         and only to the extent that and so long as the same is permitted under
         the laws and regulations governing the writing of insurance within the
         State of Texas with respect to the respective insurance that is to be
         carried by either Landlord or Tenant covering losses arising out of the
         destruction or damage to the Leased Premises or its contents or to
         other portions of the Building or to Tenant's occupancy and operation
         of the Leased Premises without invalidating or nullifying any such
         policy, or providing a defense to the applicable insurance carrier with
         respect to the coverage of any such policy, all such insurance carried
         by either Landlord or Tenant shall provide for a waiver of rights of
         subrogation against Landlord and Tenant on the part of the insurance
         carrier. Notwithstanding the foregoing, nothing contained herein shall
         require either party to obtain the inclusion of such a waiver of rights
         of subrogation in the event that, because of the cost or premium
         attributable to such waiver, the obtaining of such waiver is not
         feasible and reasonable. Except as otherwise provided in Section 5.2
         hereof or in the event that such waivers contemplated by this sentence
         will invalidate, nullify, or provide a defense to coverage under any
         such insurance policy or are not obtainable for the reasons described
         in this Subsection (f), Landlord and Tenant each hereby waive any and
         all rights of recovery, claims, actions or causes of action against the
         other, its agents, officers, or employees, or any loss or damage that
         may occur to the Leased Premises or the Building, or any improvements
         thereto, which loss or damage is covered by valid and collectible
         insurance policies, to the extent that such loss and damage is
         recoverable under such insurance policy. The waivers set forth in the
         immediately preceding sentence shall be in addition, and not
         substitution for, any other waivers, indemnities, or exclusions of
         liabilities as set forth in this Lease, including, without limitation,
         Sections 5.5 and 5.6 of the Lease.

SECTION 5.4. SURRENDER OF LEASED PREMISES. Upon termination of this Lease or
Tenant's right to possession of the Leased Premises, Tenant shall peaceably and
quietly surrender the Leased Premises to Landlord, broom-clean and in a good
state of repair and condition, excepting only ordinary wear and tear. Upon
request of Landlord, Tenant shall demolish or remove all or any portion of any
Trade Fixtures and other property or the making of any such alteration,
improvement, addition or change. Notwithstanding the foregoing, Tenant shall be
required to remove only those items which Landlord specified are to be removed
at the time that Landlord consents to the installation thereof. All such
demolition, removal and restoration shall be performed in accordance with the
conditions set forth in Section 4.2(b). Upon termination of this Lease, Tenant
will also surrender to Landlord all keys to the Leased Premises and inform
Landlord of all combinations on locks, safe, and vaults, if any, at the Leased
Premises.

SECTION 5.5. DAMAGES FROM CERTAIN CAUSES. Landlord and Landlord's agents and
employees shall not be liable or responsible to Tenant or any person claiming
through Tenant for any loss or damage or injury to business or to any property
or person in, upon or about the Leased Premises or any other portion of the
Building arising at any time from any cause, negligent or otherwise, other than
solely by reason of the gross negligence or willful misconduct of Landlord or of
Landlord's employees or agents acting within the scope of their employment or
authority.

                                       19
<PAGE>
 
SECTION 5.6. HOLD HARMLESS. Landlord shall not be liable to Tenant, or to
Tenant's agents, employees, contractors, customers or invitees or to any other
person whomsoever for any injury or damage to person or property caused by or
arising out of an act, omission or neglect of Tenant, its agents, contractors,
subtenants, employees, customers, licensees, concessionaires or invitees or any
other person entering the Building under express or implied invitation of Tenant
or other tenants of the Building, and Tenant agrees to indemnify and hold
Landlord harmless from all liability and claims for any such damage and from all
claims, costs, damages or liabilities arising out of the foregoing, including
without limitation attorneys' fees and all other out-of-pocket expenses incurred
in connection therewith. Likewise, Landlord shall indemnify and hold Tenant
harmless from all liability and claims for any damage incurred by Tenant as a
result of and from all claims for any damage incurred by Tenant as a result of
and from all claims, costs, damages, or liabilities arising out of the gross
negligence or willful misconduct of Landlord, its agents or employees,
including, without limitation, attorneys' fees and all other out-of-pocket
expenses incurred in connection therewith. In any case in which Landlord or
Tenant has agreed to indemnify the other, such indemnity shall be deemed to
include an obligation on the part of the indemnifying party to appear on behalf
of the indemnified party in any and all proceedings involving a claim or cause
of action covered by such indemnity and to defend the indemnified party against
such claim or cause of action, all at the indemnifying party's cost; provided,
however, at the option of any party indemnified hereunder, such party shall have
the right to appear on its own behalf, employ its own legal counsel and defend
any claim or cause of action indemnified in this Section, all at the cost of the
indemnifying party's.

                                    ARTICLE 6
                                    ---------

SECTION 6.1. DEFAULT BY TENANT. The occurrence of any one or more of the
following events shall constitute a default by Tenant under this Lease:

(a)      Failure of the Tenant to pay rent or any other amount due under this
         Lease within ten (10) days after Tenant's receipt of Landlord's written
         notice of such failure to pay provided Landlord shall be required to
         give such notice only once in any twelve (12) month period and
         thereafter Tenant shall be in default if any such payment is not
         received when due and without notice;

(b)      Failure of the Tenant to perform, observe, or comply with or default
         under any of the terms, covenants, conditions or provisions contained
         in Section 4.1 of this Lease within twenty-four (24) hours after
         written notice to Tenant with respect thereto, if such condition cannot
         reasonably be cured within such twenty-four (24) period, Tenant shall
         thereafter diligently and continuously prosecute such cure to
         completion within five (5) days from the date of Landlord's notice of
         such default provided that Landlord shall be required to give such
         notice only once in any twelve (12) month period and the second
         violation of the provisions contained in Section 4.1 hereof by Tenant
         shall constitute a default by Tenant hereunder whether or not Landlord
         shall provide Tenant with notice thereof and;

                                       20
<PAGE>
 
(c)      Failure of the Tenant to perform, observe, or comply with or default
         under the negative covenant or agreement set forth in Sections 4.7 and
         4.10 of the Lease and all other covenants and agreements set forth in
         this Lease which prohibit or restrict Tenant from taking or omitting to
         take any action without the consent of the Landlord or which requires
         the Tenant to take action upon the request of the Landlord;

(d)      Failure of the Tenant to perform, observe, or comply with or default
         under any of the terms, covenants, conditions or provisions contained
         in this Lease (other than covenants to pay rent, the covenants set
         forth in Sections 4.1 and 8.3 of this Lease, negative covenants and
         agreements set forth in this Lease and all other covenants and
         agreements set forth in this Lease which prohibit or restrict the
         Tenant from taking or omitting to take any action upon request of the
         Landlord) and such failure or default is not cured to Landlord's
         satisfaction within thirty (30) calendar days after the Landlord has
         given Tenant written notice thereof or, if such condition cannot
         reasonably be cured within such thirty (30) day period, Tenant shall
         thereafter diligently and continuously prosecute such cure to
         completion within eighty (80) days from the date of Landlord's notice
         of such default, except as such eighty (80) day period otherwise be
         delayed by the provisions of Section 8.1 hereunder;

(e)      The interest of Tenant under this Lease shall be levied on under
         execution or other legal process;

(f)      Any petition in bankruptcy or other insolvency proceedings shall be
         filed by or against Tenant, or any petition shall be filed or other
         action taken to declare Tenant a bankrupt or to delay, reduce or modify
         Tenant's debts or obligations or to reorganize or modify Tenant's
         capital structure or indebtedness or to appoint a trustee, receiver or
         liquidator of Tenant or of any property of Tenant, or any proceeding or
         other action shall be commenced or taken by any governmental authority
         for the dissolution or liquidation of Tenant to the extent not cured or
         removed within sixty (60) days notice from Landlord;

(g)      Tenant shall become insolvent, or Tenant shall make an assignment for
         the benefit of creditors, or Tenant shall make a transfer in fraud of
         creditors, or a receiver or trustee shall be appointed for Tenant or
         any of its properties;

(h)      Tenant shall abandon the Leased Premises or any substantial portion
         thereof;

(i)      Tenant shall do or permit to be done anything which creates or causes
         to be filed a lien, security interest or other encumbrance (whether
         consensual or created by operation of law or otherwise) against all or
         any part of the Leased Premises, the Building or any property situated
         therein or Tenant's interest in this Lease; or

(j)      The death or legal incapacity of Tenant if Tenant is an individual
         person or the termination, dissolution or liquidation of Tenant, if
         Tenant is a corporation, partnership, or other entity.

                                       21
<PAGE>
 
(k)      Failure of the Tenant to perform, observe, or comply with or default
         under any of the terms, covenants, conditions or provisions contained
         in Section 8.3 hereof and default is not cured within fifteen (15) days
         of Landlord's notice to Tenant of such default.

SECTION 6.2. LANDLORD'S REMEDIES. Upon the occurrence of any default by Tenant
under this Lease, Landlord may, at its sole option, do any one or more of the
following, without any notice or demand for possession whatsoever, and Tenant
hereby waives any and all notice and demand requirements imposed by applicable
law:

(a)      Terminate this Lease, whereupon Landlord shall have the remedies set
         forth in Section 6.3 below;

(b)      Without having terminated this Lease, enter upon and take possession of
         the Leased Premises, whereupon Landlord shall have the remedies set
         forth in Section 6.4 below; or

(c)      Upon Tenant's failure to perform, observe or comply with the covenants
         set forth in Sections 2.2, 4.1, or 4.7 of this Lease, Landlord may,
         without terminating this Lease and without taking possession of the
         Leased Premises, collect from Tenant, in addition to any rent payable
         by Tenant to Landlord under this Lease, as liquidated damages, a sum
         equal to twice the Base Rental (computed on a daily basis) for each day
         or any portion thereof that such default by Tenant continues, Landlord
         and Tenant agreeing that actual damages which might be sustained by
         Landlord by reason of such failure are uncertain and difficult to
         ascertain and that said sum would be reasonable and just compensation
         for such failure.

SECTION 6.3. TERMINATION OF LEASE. Upon termination of this Lease by Landlord,
pursuant to Section 6.2(a), Landlord may forthwith repossess the Leased Premises
and be entitled to recover as damages a sum of money equal to the total of (i)
the cost of recovering the Leased Premises, (ii) the cost of removing and
storing Tenant's or any other occupant's property, (iii) the unpaid rent accrued
at the date of termination, and (iv) any other sum of money or damages that may
be owed to Landlord as the result of the exercise of Landlord's rights at law or
in equity.

SECTION 6.4. TERMINATION OF POSSESSION. Upon termination of Tenant's right of
possession to the Leased Premises pursuant to Section 6.2(b), Landlord may
repossess the Leased Premises by forcible entry or detainer suit or otherwise,
without demand or notice of any kind to Tenant and without terminating this
Lease, in which event Landlord may (but shall not be obligated to) relet the
same for the account of Tenant for such rent and upon such terms as shall be
satisfactory to Landlord. In such event, Tenant shall be liable for and shall
pay to Landlord all rent payable by Tenant under this Lease plus an amount equal
to (i) the cost of recovering possession, (ii) the cost of decorations, repairs,
changes, alterations and additions to the Leased Premises, (iii) the cost of
collection of the rent accruing from such reletting, and (iv) any other costs
incurred by Landlord in connection with such reletting, reduced by any sums
received by Landlord through reletting the Leased Premises; provided, however,
that in no event shall Tenant be entitled to any excess of any sums obtained by
reletting over and above rent provided in this Lease to be paid by Tenant to
Landlord. For the purpose of such reletting, Landlord is

                                       22
<PAGE>
 
authorized to decorate or to make any repairs, changes, alterations or additions
in or to the Leased Premises that Landlord may deem necessary or advisable.
Landlord may file suit to recover any sums falling due under the terms of this
Section from time to time, and no delivery to or recovery by Landlord of any
portion due Landlord hereunder shall be any defense in any action to recover any
amount not theretofore reduced to judgment in favor of Landlord. No reletting
shall be construed as an election on the part of Landlord to terminate this
Lease unless a written notice of such intention is given to Tenant by Landlord.
Notwithstanding any such reletting without termination, Landlord may at any time
thereafter elect to terminate this Lease for such previous default.

SECTION 6.5. LANDLORD'S RIGHT TO PERFORM TENANT'S OBLIGATIONS., Should Tenant
fail to perform any of its obligations hereunder, Landlord may (but shall not be
obligated to), after written notice to Tenant, (except in an emergency, when no
notice shall be required) enter upon the Leased Premises and perform all or any
part of such obligations. Upon demand, Tenant shall reimburse Landlord for the
cost to Landlord of performing such obligations plus profit and overhead in an
amount equal to fifteen percent (15%) of such cost. No action taken by Landlord
under this Section shall relieve Tenant from any of its obligations under this
Lease or from any consequences or liabilities arising from the failure to
perform such obligations.

SECTION 6.6. CUMULATIVE REMEDIES. The rights and remedies of Landlord under this
Article shall be non-exclusive and shall be in addition to and cumulative of all
other remedies available to Landlord under this Lease or at law or in equity.

SECTION 6.7.  LANDLORD'S LIEN. Intentionally omitted.

SECTION 6.8. HOLDING OVER. In the event Tenant remains in possession of the
Leased Premises after the expiration or termination of this Lease without the
execution of a new lease, then Tenant shall be deemed to be occupying the Leased
Premises as a tenant from month to month at a rental equal to 150% of the Base
Rental for the first forty-five (45) days and 200% of the Base Rental thereafter
and shall otherwise remain subject to all the conditions, provisions and
obligations of this Lease insofar as the same are applicable to a month to month
tenancy. No holding over by Tenant after the expiration or termination of this
Lease shall be construed to extend the Lease Term or in any other manner be
construed as permission by Landlord to hold over.

SECTION 6.9. SECURITY DEPOSIT. Tenant shall pay the Security Deposit to Landlord
on the date this Lease is executed by Tenant. Landlord may commingle the
Security Deposit with its other funds and shall receive and hold the Security
Deposit without liability for interest. Upon default by Tenant, Landlord may,
from time to time, without prejudice to any other remedy, apply such Security
Deposit to the extent necessary to make good any arrears of rental or any other
damage, injury, expense or liability caused by Landlord by reason of default by
the Tenant. After any such application of Security Deposit, Tenant shall, upon
request of Landlord, pay to Landlord the amount so applied so as to restore the
Security Deposit to its original amount. Any remaining balance of the Security
Deposit shall be returned by Landlord to Tenant within a reasonable period of
time after the termination of this Lease. If Landlord transfers its

                                       23
<PAGE>
 
interest in the Leased Premises during the term of this Lease, Landlord may
assign the Security Deposit to the transferee and thereafter shall have no
further liability for the return of such Security Deposit.

                                    ARTICLE 7
                                    ---------

SECTION 7.1. ATTORNEY'S FEES AND OTHER EXPENSES. In the event of the default by
either party hereto in the performance or observance of any of the terms,
agreements or conditions contained in this Lease, the defaulting party shall be
liable for and shall pay the prevailing party all expenses incurred by the
prevailing party in enforcing any of the prevailing party's remedies for any
such default, including, without limitation, the prevailing party's reasonable
attorney's fees.

SECTION 7.2. AMENDMENTS, BINDING EFFECT. This Lease may not be altered, changed
or amended, except by instrument in writing signed by both parties hereto. No
provision of this Lease shall be deemed to have been waived by Landlord unless
such waiver be in writing signed by Landlord and addressed to Tenant, nor shall
any custom or practice which may evolve between the parties in the
administration of the terms hereof be construed to waiver or lessen the right of
Landlord to insist upon the performance by Tenant in strict accordance with the
terms hereof. The terms and conditions contained in this Lease shall apply to,
inure to the benefit of, and be binding upon the parties hereto, and upon their
respective successors in interest and legal representatives, except as otherwise
herein expressly provided.

SECTION 7.3. NON-WAIVER. No course of dealing between Landlord and Tenant or any
other person, nor any delay on the part of Landlord in exercising any rights
under this Lease, nor any failure to enforce any provision of this Lease, nor
the acceptance of rental by Landlord shall operate as a waiver of any rights of
Landlord, except to the extent, if any, expressly waived in writing by Landlord.
The waiver by Landlord of any agreement, condition or provision herein contained
shall not be deemed a waiver of any subsequent breach of the same or any other
agreement, condition or provision herein contained.

SECTION 7.4. NOTICES. Any notice or other communications to Landlord or Tenant
required or permitted to be given under this Lease must be in writing and shall
be effectively given if hand delivered or transmitted by facsimile to the
addresses for Landlord and Tenant stated above or if sent by United States Mail,
certified or registered, return receipt requested, to said addresses. Any notice
mailed shall be deemed to have been given three (3) calendar days following the
date of deposit of such item in a depository of the United States Postal
Service. Any notice by facsimile shall be deemed delivered upon confirmation of
receipt on the day of receipt or, if after 5:00 p. m. the next business day. Any
other form of notice effected other than by mail shall be deemed to have been
given at the time of actual delivery. Either party shall have the right to
change its address to which notices shall thereafter be sent by giving the other
written notice thereof.

SECTION 7.5. INTEREST. All amounts of money payable by Tenant to Landlord under
this Lease shall bear interest from the date due until paid at the rate of
interest set forth in Section 2.3.

                                       24
<PAGE>
 
SECTION 7.6. MERGER OF ESTATES. The voluntary or other surrender of this Lease
by Tenant or a mutual cancellation thereof, shall not constitute a merger; and
upon such surrender or cancellation of this Lease, Landlord shall have the
option, in Landlord's sole discretion, to (i) either terminate all or any
existing subleases or subtenancies, or (ii) assume Tenant's interest in any or
all subleases or subtenancies.

SECTION 7.7. OTHER TENANTS OF BUILDING. Neither this Lease nor Tenant's
continued occupancy of the Leased Premises is conditioned upon the opening of
any store or business in the Building, nor upon the continued operation of any
such store or business.

SECTION 7.8. CONSENT BY LANDLORD. In all circumstances under this Lease where
the prior consent or permission of Landlord is required before Tenant is
authorized to take any particular type of action, such consent must be in
writing and the matter of whether to grant such consent or permission shall be
within the sole and exclusive judgment and discretion of Landlord, except as set
forth herein, and it shall not constitute any nature of breach by Landlord under
this Lease or any defense to the performance of any covenant, duty or obligation
of Tenant under this Lease that Landlord delayed or withheld the granting of
such consent or permission.

SECTION 7.9. LEGAL INTERPRETATION. This lease and the rights and obligations of
the parties hereto shall be interpreted construed and enforced in accordance
with the laws of the State of Texas and the United States. All obligations of
the parties hereto shall be performable in, and all legal actions to enforce or
construe this Lease shall be instituted in the courts of Dallas County, Texas.
The determination that one or more provisions of this Lease is invalid, void,
illegal or unenforceable shall not affect or invalidate the remainder. All
obligations of either party requiring any performance after the expiration of
the Lease Term shall survive the expiration of the Lease Term and shall be fully
enforceable in accordance with those provisions pertaining thereto. Section
titles appearing in this Lease are for convenient reference only and shall not
be used to interpret or limit the meaning of any provision of this Lease.

SECTION 7.10. ENTIRE AGREEMENT. Tenant agrees that this Lease supersedes and
cancels any and all previous statements, negotiations, arrangements, brochures,
agreements and understandings, if any, between Landlord and Tenant or displayed
by Landlord to Tenant with respect to the subject matter of this Lease, the
Leased Premises or the Building, and that there are no representations,
agreements or warranties (express or implied, oral or written) between Landlord
and Tenant with respect to the subject matter of this Lease, the Leased Premises
or the Building other than contained in this Lease.

SECTION 7.11. ASSIGNMENT BY LANDLORD. Landlord shall have the right at any time
to transfer and assign in whole or in part, by operation of law or otherwise,
its rights, benefits, privileges, duties and obligations hereunder or in the
Property.

SECTION 7.12. TENANT'S AUTHORITY. Tenant represents and warrants that it has the
full right, power and authority to enter into this Lease and to perform its
obligations hereunder, and that upon execution of this Lease by Tenant, this
Lease shall constitute a valid and legally binding obligation of Tenant. If
Tenant signs as a corporation, each of the persons executing this

                                       25
<PAGE>
 
Lease on behalf of Tenant does hereby covenant and warrant that Tenant is a duly
and validly existing corporation, that the execution of this Lease by such
persons on behalf of Tenant has been duly authorized by all necessary corporate
action and that Tenant is qualified to do business in the State of Texas.

SECTION 7.13. LANDLORD'S LIABILITY. Any provisions of this Lease to the contrary
notwithstanding, Tenant hereby agrees that no personal, partnership or corporate
liability of any kind or character whatsoever now attaches or at any time
hereafter under any condition shall attach to Landlord or its partners or
venturers for payment of any amounts payable under this Lease or for the
performance of any obligation under this Lease. The exclusive remedy of Tenant
for the failure of Landlord to perform any of its obligations under this Lease
shall be to proceed against the interest of Landlord in and to the Building. In
no event shall Landlord incur any liability or obligation to Tenant or other
person or entity with respect to any action, omission, or inaction, negligent or
otherwise, of Landlord, except as such may be due to the gross negligence or
willful misconduct of Landlord.

SECTION 7.14. TIME OF ESSENCE. In all instances where Tenant is required under
this Lease to pay any sum or do any act at a particular time or within a
particular period, it is understood that time is of the essence.

SECTION 7.15. INSTRUMENTS AND EVIDENCE REQUIRED TO BE SUBMITTED TO LANDLORD.
Each written instrument and all evidence of the existence or non-existence of
any circumstances or condition which is required by this Lease to be furnished
to Landlord shall in all respects be in form and substance satisfactory to
Landlord, and the duty to furnish such written instrument or evidence shall not
be considered satisfied until Landlord shall have acknowledged that it is
satisfied therewith.

SECTION 7.16. COUNTERPARTS. This Lease may be executed in any number of
counterparts, each of which when so executed and delivered shall be an original,
but such counterparts shall together constitute one and the same instrument.

SECTION 7.17. GENDER AND NUMBER. The pronouns of any gender shall include the
other gender and either the singular or the plural shall include the other.

SECTION 7.18. RECORDATION. Tenant agrees not to record this Lease or any
instrument to which this Lease may now or hereafter be attached.

                                    ARTICLE 8
                                    ---------

SECTION 8.1. FORCE MAJEURE. Except for the payment of Base Rental or any
additional sums payable by Tenant hereunder, whenever a period of time is herein
prescribed for the taking of any action by Landlord or Tenant, Landlord or
Tenant shall not be liable or responsible for, and there shall be excluded from
the computation of such period of time, any delays due to strikes, riots, acts
of God, shortages of labor or materials, war, governmental laws, regulations or
restrictions, or any other cause whatsoever beyond the control of such party.

                                       26
<PAGE>
 
SECTION 8.2. COMMISSIONS. Landlord has agreed to pay commission to Grubb & Ellis
with respect to the negotiation and execution of this Lease. Tenant hereby
indemnifies and holds Landlord harmless against any loss, claim, expense or
liability with respect to any other commissions or brokerage fees claimed on
account of the execution and/or renewal of this Lease or the expansion of the
Leased Premises hereunder, if applicable, due to any action by Tenant. The
provisions of this paragraph shall survive the termination of this Lease.

SECTION 8.3. USE OF THE TERM "INFOMART". Tenant may use the term "INFOMART" in
any of its activities, provided that (a) such usage by Tenant is in compliance
with such agreement relative to Landlord's use of the term "INFOMART" ("License
Agreement") and (b) copies of all proposed written materials and advertising
containing reference to the term "INFOMART" shall be furnished to Landlord in
advance for its review and written approval. Any permitted use of the term
"INFOMART" by Tenant shall additionally include the phrase "The Technology
Community" immediately after the first (1st) usage of such term in any material.
Landlord shall notify Tenant in writing after such proposed usage has been
verified, and Tenant may thereafter commence such requested usage. Tenant shall
not permit any third party to use the term "INFOMART" in any of its activities
and shall report to Landlord any unauthorized uses of such term which comes to
its attention. The breach by Tenant of any provisions of this Section 8.3 shall
constitute an event of default under this Lease and Tenant shall cease and
desist immediately from any unauthorized use within fifteen (15) days of
Landlord's notice of such breach. Tenant shall indemnify and hold Landlord
harmless from against any loss, cost, claim, liability, cause of action, or
expense whatsoever (including, without limitation, attorney's fees and other
costs and expenses of defending against any such claim) arising or alleged to
arise from any unauthorized use by Tenant, or its agents or employees of the
term "INFOMART".

SECTION 8.4. EFFECT OF DELIVERY OF THIS LEASE. Landlord has delivered a copy of
this Lease to Tenant for Tenant's review only, and the delivery hereof does not
constitute an offer or option to Tenant. This Lease shall not be effective until
a copy executed by both Landlord and Tenant is delivered to and accepted by
Landlord, and this Lease has been approved by Landlords' mortgagee.

SECTION 8.5. EXHIBITS, SCHEDULES AND RIDERS. The Exhibits and Riders attached to
this Lease are hereby incorporated herein and hereby made a part of this Lease.

                                       27
<PAGE>
 
IN TESTIMONY HEREOF, the parties have executed this Lease as of the day and year
first above written.

                             L A N D L O R D
                             ---------------

                             INFOMART-Dallas, L.P., a Texas limited partnership

                             By:INFOMART USA, L.P., a Texas limited partnership

                             By: /s/ Thomas E. Jones
                                --------------------------------
                             Name: Thomas E. Jones

                             Title:  Authorized Agent

                             T E N A N T
                             -----------

                             FOCAL COMMUNICATIONS CORPORATION OF
                             TEXAS, a Delaware corporation

                             By: /s/ Brian F. Addy
                                --------------------------------
                             Name:   Brian F. Addy
                                  ------------------------------
                             Title:  Executive Vice President
                                   -----------------------------

Exhibit "A" - Property Description
Exhibit "B" - Building Rules
Exhibit "C" - Designation of Leased Premises
Exhibit "D" - INFOMART Policy Statement
Exhibit "E" -  Parking
Exhibit "F" - Telecommunications Equipment License
Exhibit "G" - Satellite/Antenna License
Exhibit "H" - Generator
Exhibit "I" - Renewal Option
Exhibit "J" - Work Letter (Allowance)
Exhibit "K" - Rooftop Cooling Provisions
Exhibit "L" - Subordination, Non-Disturbance and Attornment Agreement


                                       28
<PAGE>
 
                                   EXHIBIT "A"
                                   -----------
      To Lease Agreement By and Between INFOMART-Dallas, L.P., as Landlord
            and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                              PROPERTY DESCRIPTION
                              --------------------

BEING a 25.454 acre tract of land situated in the City of Dallas, Dallas County,
Texas and out of the James A. Sylvester Survey, Abstract No. 1383 and being a
part of City of Dallas Block No. 6053, also being the same tract of land
conveyed to Dallas Market Center Company by a Special Warranty Deed recorded in
Volume 82113, Page 3240 of the Deed Records of Dallas County, Texas, said 25.454
acre tract of land being more particularly described as follows:

BEGINNING at a 1/2 inch iron rod found for the point of intersection of the
southwesterly right-of-way line of the Chicago Rock Island and Pacific Railroad
with the northwesterly right-of-way line of Oak Lawn Avenue;

THENCE with the northwesterly right-of-way line of Oak Lawn Avenue the
following:

         South 31 31'40" West a distance of 366.74 feet to an "X" chiseled in
         concrete found for corner in a curve to the right, the radius point of
         said curve bearing North 50 08'58" West a distance of 241.00 feet from
         said "X";

         Southwesterly with said curve to the right through a central angle of
         03 09'20" an arc distance of 13.27 feet to an "X" chiseled in concrete
         set for the point of reverse curvature of a curve to the left having a
         radius of 259.00 feet;

         Southwesterly with said curve to the left through a central angle of 11
         28'43" an arc distance of 51.89 feet to a 1/2 inch iron rod found for
         the point of reverse curvature of a curve to the right having radius of
         129.00 feet;

         Southwesterly with said curve to the right through a central angle of
         24 06'22" an arc distance of 138.22 feet to a 1/2 inch iron rod set for
         the point of compound curvature of a curve to the right having a radius
         of 50.00 feet;

         Northwesterly with said curve to the right through a central angle of
         24 06'22" an arc distance of 21.04 feet to a 1/2 inch iron rod found in
         the northeasterly right-of-way line of Stemmons Freeway for the point
         of compound curvature of a curve to the right having a radius of
         1130.92 feet;

         THENCE with the northeasterly right-of-way line of Stemmons Freeway the
         following:

         Northwesterly with said curve to the right through a central angle of
         07 24'40" an arc distance of 146.28 feet to a 1/2 inch iron rod found
         for the point of tangency of said curve;

                                       29
<PAGE>
 
         North 55 33'45" West a distance of 816.18 feet to a 1/2 inch iron rod
         found for point of curvature of a curve to the left having a radius of
         3289.04 feet;

         Northwesterly with said curve to the left through a central angle of 01
         23'21" an arc distance of 79.74 feet to a bolt in concrete found for
         the most southerly corner of a tract of land leased to Southwestern
         Furniture Mart Co. from Industrial Properties Corporation as recorded
         in Volume 67076, Page 0690 of the Deed Records of Dallas County, Texas;

THENCE departing the northerly right-of-way line of Stemmons Freeway with the
easterly line of the Southwestern Furniture Mart Company tract, North 09 21'30"
East a distance of 1064.46 feet to a 1/2 inch iron rod found for corner in the
curving southwesterly right-of-way line of the Chicago, Rock Island and Pacific
Railroad, the radius point of said curve being situated South 33 11'48" West a
distance of 1599.88 feet;

THENCE with the southerly right-of-way lien of the Chicago, Rock Island and
Pacific Railroad the following:

         Southeasterly with said curve to the right through a central angle of
         02 41'48" an arc distance of 75.30 feet to a 1/2 inch iron rod found
         for corner;

         North 52 07'00" East a distance of 30.11 feet to a 1/2 inch iron rod
         found for corner in a curve to the right, the radius point of said
         curve being situated South 32 19'18" West a distance of 1553.95 feet;

         Northwesterly with said curve to the right through a central angle of
         21 26'39" an arc distance of 581.59 feet to a 1/2 inch iron rod set for
         corner;

         North 45 16'10" East a distance of 53.07 feet to 1/2 inch iron rod set
         for corner;

         South 31 48'40" East a distance of 976.20 feet to the POINT OF
         BEGINNING;

CONTAINING an area of 25.454 acres of land.

                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       30
<PAGE>
 
                                   EXHIBIT "B"
                                   -----------

      To Lease Agreement By and Between INFOMART-Dallas, L.P., as Landlord
            and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                              RULES AND REGULATIONS
                              ---------------------

1.       No additional locks shall be placed on the doors of the Leased Premises
         by Tenant, nor shall any existing locks be changed unless Landlord is
         immediately furnished with two keys thereto. Landlord will without
         charge furnish Tenant with two keys for each lock existing upon the
         entrance doors when Tenant assumes possession with the understanding
         that at the termination of the lease these keys shall be returned or
         paid for at five dollars ($5.00) each. A deposit of one dollar ($1.00)
         each shall be required for additional keys.

2.       Tenant shall not at any time display a "For Rent" sign upon the
         Building or the Leased Premises, or advertise the Leased Premises for
         rent.

3.       Safes and other unusually heavy objects shall be placed by Tenant only
         in such places as may be approved by Landlord. Any damage caused by
         overloading the floor or by taking in or removing any object from the
         Leased Premises or the Building shall be paid by Tenant.

4.       Windows facing on corridors shall at all times be wholly clear and
         uncovered (except for such signs as Landlord may approve) so that a
         full unobstructed view of the interior of the Leased Premises may be
         had from the corridors, unless otherwise approved in writing by
         Landlord.

5.       No vehicles or animals shall be brought into the Building, other than
         as required by handicapped persons.

6.       Tenant shall not make any changes in the pipes, ducts, or wiring
         serving the Leased Premises or add any additional pipes, ducts, or
         wiring without the prior written consent of Landlord, and any such
         changes or additions shall be made in such manner as Landlord may
         direct.

7.       No sign, tag, label, picture, advertisement, or notice (other than
         price tags of customary size used in marking samples) shall be
         displayed, distributed, inscribed, painted or affixed by Tenant on any
         part of the outside of the Building or of the Leased Premises without
         the prior written consent of the Landlord.

8.       In the event Landlord should advance upon the request, or for the
         account of the Tenant, any amount for labor, material, packing,
         shipping, postage, freight or express upon articles delivered to the
         Leased Premises or for the safety, care, and cleanliness of the Leased
         Premises, the amount so paid shall be regarded as additional rent and
         shall be due and payable forthwith to the Landlord from the Tenant.

                                       31
<PAGE>
 
9.       The corridors and hallways of the Building shall not be used by Tenant
         for any purpose other than ingress to or egress from the Leased
         Premises.

10.      Tenant shall not do or permit to be done within the Leased Premises
         anything which would unreasonably annoy or interfere with the rights of
         other tenants in the Building, or which might constitute a potential
         hazard to other tenants or visitors.

11.      During the thirty (30) days prior to the expiration of this Lease,
         Landlord may show the Leased Premises to prospective tenants.

12.      Tenant shall not put or operate any steam engine, boiler, industrial
         machinery or stove in the Building or upon the Leased Premises or do
         any cooking thereon or use or allow to be kept in the Building or upon
         the Leased Premises any explosives or any kerosene, camphene, bottled
         gas, oil or other highly flammable materials, except gas supplied
         through metal pipes for heating purposes and normal and customary
         cleaning and janitorial supplies to the extent permitted under
         applicable laws.

13.      Landlord reserves the right to prescribe reasonable qualifications for
         admission into the Building.

14.      Models, salespersons or other employees or representatives of Tenant,
         shall not model, demonstrate display, or show in any manner any
         merchandise outside of the Leased Premises in the Building or on the
         Property without Landlord's prior written consent.

15.      As a courtesy, but not as an obligation, Landlord may, at Landlord's
         option, upon request by Tenant, receive and store articles or
         merchandise delivered to Tenant at the Building; provided, however that
         such articles of merchandise are properly addressed and identified and
         all postage, handling and delivery charges are prepaid by Tenant.
         Landlord assumes no responsibility whatsoever for the loss, damage or
         destruction of such articles of merchandise received at the Building by
         Landlord on behalf of Tenant, and Tenant hereby waives all claims
         against Landlord for any damage or loss arising at any time from the
         loss, damage or destruction of such articles of merchandise. Tenant
         agrees to pay to Landlord as additional rent the amount of all storage,
         delivery, handling and other expenses incurred by Landlord as a result
         of the receipt and storage of such articles of merchandise.

16.      Canvassing, peddling, soliciting and distribution of handbills or any
         other written material in the Building or in the Building's parking
         areas are prohibited, and each tenant shall cooperate to prevent the
         same.

17.      If the Leased Premises front on the atrium within the Building, Tenant
         shall cause the Leased Premises to be kept open for business and
         occupied by Tenant's personnel during all normal business hours of the
         Building.

18.      These Rules and Regulations are in addition to, and shall not be
         construed to in any way

                                       32
<PAGE>
 
         modify or amend, in whole or in part, the terms, covenants, agreements
         and conditions of any lease of space in the Building.

19.      Landlord reserves the right to make such other and reasonable rules and
         regulations as in its judgment may from time to time be needed for the
         safety, care and cleanliness of the Building, and for the preservation
         of good order therein.

20.      Smoking is not permitted within the Building. Smoking within the Leased
         Premises is at the discretion of Tenant, provided, however, that such
         smoke does not migrate into the Building's common areas, hallways, etc.
         or into another tenant's premises. Tenant hereby indemnifies Landlord
         from any and all claims resulting from Tenant's permitting of smoking
         within the Leased Premises.

21.      Tenant shall comply with the INFOMART Policy Statement. Tenant shall be
         liable for all injuries and damages sustained by Landlord or Landlord's
         agents or by other tenants, occupants, or invitees of the Building by
         reason of any breach of the requirements of the INFOMART Policy
         Statement by Tenant or Tenant's agents, employees or invitees.

22.      Landlord may amend these Rules and Regulations from time to time and
         such changes shall be binding upon Tenant.



                                   INITIALS

                    Landlord                 Tenant
                            -----------            -----------


                                       33
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                                       34
<PAGE>
 
                                   EXHIBIT "C"
                                   -----------
            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                         DESIGNATION OF LEASED PREMISES
                         ------------------------------
                        (For illustrative purposes only)

                            [Floorplan Appears here]




                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       35
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                                       36
<PAGE>
 
                                  EXHIBIT "D"
                                  -----------

    To Lease Agreement By and Between INFOMART-Dallas, L.P., as Landlord and
              FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                            INFOMART POLICY STATEMENT
                            -------------------------
           GENERAL POLICIES AND PROCEDURES REGARDING INFOMART, DALLAS
           ----------------------------------------------------------


1.       PERMANENT TENANT QUALIFICATIONS. Permanent tenants must be producers of
         hardware, software or services utilizing information processing
         equipment unless otherwise specifically approved by Landlord. If the
         tenant's business includes the resale of products or services, the
         tenant must add to or enhance the value of such products or services.

2.       TEMPORARY EXHIBITOR REGULATIONS.

         (a)      During designated temporary trade events sponsored by Landlord
                  which are conducted in conjunction with the use of permanent
                  showrooms and which include the rental of temporary exhibit
                  space, permanent tenants will be offered a priority selection
                  of such temporary exhibit space based in the initial year upon
                  the dates on which such permanent tenants entered into leases
                  for space within the Building and in subsequent years on a
                  priority basis reasonably determined by Landlord.

         (b)      When temporary exhibit space is used in conjunction with
                  permanent showrooms, non-information processing industry
                  representatives may display wares for specific trade markets.

         (c)      Temporary space areas may be rented independent of permanent
                  showrooms, in which event Landlord will have sole discretion
                  as to exhibition policies.

3.       BUSINESS HOURS. Permanent showrooms bounded by an atrium wholly or
         partially will be open and staffed during all normal business hours of
         the Building. Showrooms must be open during all Landlord sponsored
         trade events with exceptions approved in writing by Landlord. The hours
         of these events will be established by Landlord.

4.       SALES POLICY. Warehousing and on-site delivery to customers is
         prohibited in permanent showrooms and in exhibit space when used in
         conjunction with showrooms. Payment for products or services that are
         of a retail sales nature are prohibited (provided, however, that
         payment or partial payment for orders taken at the Building for future
         delivery to a buyer will be allowed if it is within the applicable
         tenant's normal business practice and is not of a retail sales nature,
         it being the intention hereof to permit payments or partial payments
         intended to bind an order for future delivery without in any way
         qualifying or circumventing the prohibition within the Building against
         retail sales).

                                       37
<PAGE>
 
5.       ACCESS AND ADMISSION OF VISITORS. Landlord reserves the right to
         implement and/or use any or all of the following policies with regard
         to access and admission of visitors into the Building. Tenant will
         receive prior notice of any change in the policy.

         (a)      All entrants to the Building will be registered and issued an
                  identification badge with the exception of visitors with a
                  pre-arranged appointment with a specific tenant.
                  Appointment-only visitors will be issued a badge which
                  requires such visitors to be accompanied by the applicable
                  inviter. Appointment-only visitors will not be required to
                  register on the Building's visitor database.

         (b)      Terms of issuance of badges will be annual with the exception
                  of specific trade events, including without limitation
                  conferences and symposia, in which event badges will be valid
                  only during the scheduled event. Temporary user badges will be
                  issued to non-scheduled daily visitors.

         (c)      A registration fee will be established by Landlord which will
                  defray the cost of registration and better ensure the quality
                  of visitors.

         (d)      Permanent tenants' badges will be issued based on one badge
                  per 500 Usable Square Feet of space, with additional badges
                  available upon payment of a registration fee cost or annual
                  renewal cost.

         (e)      Members of the press and educational institutions will be
                  issued a maximum of five annual complimentary badges with
                  additional badges available upon payment of the standard
                  registration fee.

         (f)      Employees and agents of Landlord will be issued badges at the
                  discretion of Landlord.

         (g)      Visitor registration information deemed appropriate by
                  Landlord will be made available to permanent tenants.
                  Information regarding tenant invitees will be proprietary and
                  not available to tenants. Attendee registration lists of
                  externally sponsored events will be the property of the
                  sponsoring group.

6.       PUBLIC FUNCTION/ON-SITE ACCOMMODATIONS.

         (a)      A visitor information directory system will be provided by
                  Landlord to assist visitors in locating vendors. Tenant and
                  exhibitor listings will be categorized by company name and
                  product offerings. Each tenant is eligible to multiple product
                  listings applicable, up to a maximum of one product category
                  listing per 500 Usable Square Feet of permanent lease space.
                  Additional listings may be issued at a nominal fee subject to
                  product eligibility.

         (b)      Tenant's meeting room use will be coordinated on a reservation
                  basis and all

                                       38
<PAGE>
 
                  tenants will be eligible. Standard fees will be applied and
                  Landlord will control the rental of these areas and the use of
                  the areas will be coordinated by the buyer/tenant services
                  department of Landlord. Reservations for meeting room space
                  within the Building will be on a first-come first-served
                  basis.

7.       MERCHANDISING OF INFOMART. INFOMART reserves the right to list tenants,
         partially or in entirety, of INFOMART in merchandising programs and
         agrees that such use shall not contain editorial references regarding
         specific tenants.

8.       AMENDMENTS TO GENERAL POLICIES AND PROCEDURES. Landlord may amend its
         policies from time to time and such changes shall be binding upon
         Tenant.





                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       39
<PAGE>
 
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                                       40
<PAGE>
 
                                   EXHIBIT "E"
                                   -----------
            To Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                                     PARKING
                                     -------

This Exhibit "E" ("Exhibit") describes and specifies Tenant's non-exclusive
right to use non-reserved parking spaces ("Garage Spaces") located inside the
Building's exterior card access parking garage ("Parking Garage"), and reserved
parking spaces ("Lower Level Spaces") on the lower level of the Building's
interior card access parking garage ("Lower Level Garage"). Additionally, spaces
in the surface parking lots associated with the Building and located on the
Property ("Surface Parking") are provided for the non-exclusive and common use
of Landlord, all tenants of the Building, and their respective guests and
invitees. Utilization of the Surface Parking is subject to availability (and
Landlord shall have no obligation to provide available Surface Parking) and to
such rules and regulations as may be promulgated by Landlord from time to time.
Use of the Parking Garage, Lower Level Garage and the Surface Parking is subject
to the terms and conditions set forth below.

1.       DEFINITIONS.    The terms which are defined in the Lease shall have the
         same meaning in this Exhibit.

2.       GRANT AND RENTAL FEE. Provided no event of default has occurred and is
         continuing under the Lease, Tenant shall be permitted non-exclusive use
         of nineteen (19) Garage Spaces in the Parking Garage during the Lease
         Term at such monthly rates and subject to such terms, conditions, and
         regulations as are, from time to time, promulgated by Landlord and
         charged or applicable to patrons of said parking Garage for spaces
         similarly situated within said Parking Garage. The parking rate for
         each of the Garage Spaces as of the date hereof is $45.00. Provided no
         event of default has occurred and is continuing under the Lease, Tenant
         shall be permitted use of six (6) reserved Lower Level Spaces in the
         Lower Level Garage during the Lease Term at such monthly rates and
         subject to such terms, conditions, and regulations as are, from time to
         time, promulgated by Landlord and charged or applicable to patrons of
         said Lower Level Garage. The parking rate for each of the Lower Level
         Spaces as of the date hereof is $60.00 for spaces designated on the
         attached Schedule 1 "Lower Level Garage Pricing Schedule" as "circle"
         parking and $90.00 for spaces designated as "diamond" parking. Tenant
         shall also have the right to use the Surface Parking, free of charge,
         during the Lease Term.

3.       RISK.  All motor vehicles (including all contents thereof) shall be
         parked in the Garage Spaces, Lower Level Spaces or in the Surface
         Parking, as applicable, at the sole risk of Tenant, its employees,
         agents, invitees and licensees, it being expressly agreed and
         understood that Landlord has no duty to insure any of said motor
         vehicles (including the contents thereof), and that Landlord is not
         responsible for the protection and security of such vehicles.  Landlord
         shall have no liability whatsoever for any property damage and/or
         personal injury which might occur as a result of or in connection with
         the parking

                                       41
<PAGE>
 
         of said motor vehicles in any of the Garage Spaces, Lower Level Spaces
         or in the Surface Parking, as applicable, and Tenant hereby agrees to
         indemnify and hold Landlord harmless from and against any and all
         costs, claims, expenses, and/or causes of action which Landlord may
         incur in connection with or arising out of Tenant's use of the Garage
         Spaces, Lower Level Spaces or the Surface Parking pursuant to this
         Agreement.

4.       RULES AND REGULATIONS. In its use of the Garage Spaces, Lower Level
         Spaces and the Surface Parking, Tenant shall follow all of the Rules
         and Regulations of the Building (attached to the Lease as Exhibit "B")
         applicable thereto, as the same may be amended from time to time. Upon
         the occurrence of any breach of such rules or default by Tenant under
         the Lease, Landlord shall be entitled to terminate this Exhibit, in
         which event Tenant's right to utilize the Garage Spaces, Lower Level
         Spaces and/or the Surface Parking shall thereupon automatically cease.

5.       SECURITY. Landlord shall be entitled to utilize whatever access device
         Landlord deems necessary (including but not limited to the issuance of
         parking stickers or access cards), to insure that only tenants
         authorized to use spaces in the Parking Garage and Lower Level Garage
         are using such spaces.  In the event Tenant, its agents or employees
         wrongfully park in any of the Parking Garage's or Lower Level Parking
         Garage's spaces, Landlord shall be entitled and is hereby authorized to
         have any such vehicle towed away, at Tenant's sole risk and expense,
         and Landlord is further authorized to impose upon Tenant a penalty of
         $25.00 for each such occurrence.  Tenant hereby agrees to pay all
         amounts falling due hereunder upon demand therefor, and the failure to
         pay any such amount shall additionally be deemed an event of default
         under the Lease, entitling Landlord to all of its rights and remedies
         thereunder.

6.       ADDITIONAL SPACES. In the event that Tenant expands the Leased
         Premises, Tenant shall be entitled to additional Garage Spaces within
         the Parking Garage based upon a ratio of one (1) additional Space per
         additional 1,000 Usable Square Feet incorporated into the Leased
         Premises and additional Lower Level Spaces within the Lower Level
         Garage based upon a ratio of one reserved parking space per 3,000
         Rentable Square Feet incorporated into the Lease Premises.  Such
         additional Garage Spaces and Lower Level Spaces shall be subject to
         such monthly rates, terms, conditions, and regulations as are, from
         time to time, promulgated by Landlord and charged or applicable to
         patrons of said Parking Garage or Lower Level Garage for spaces
         similarly situated within said Parking Garage or Lower Level Garage.

Schedule 1- Lower Level Garage Price Schedule



                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       42
<PAGE>
 
                                  SCHEDULE "1"
                                  ------------
      To Exhibit E to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                        Lower Level Garage Price Schedule
                        (For illustrative purposes only)


                            [Floorplan appears here]


                                       43
<PAGE>
 
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                                       44
<PAGE>
 
                                   EXHIBIT "F"
                                   -----------

            To Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                      TELECOMMUNICATIONS EQUIPMENT LICENSE
                      ------------------------------------

This Exhibit "F" describes the license to install and operate certain specified
"Telecommunications Equipment" in the Building which is being granted by
Landlord to Tenant upon the following terms and conditions:

1.       DEFINED TERMS. For purposes of this Exhibit, all terms defined in this
         Lease (including other exhibits in this Lease) will be used in this
         Exhibit without further definition. In addition, when delineated with
         initial capital letters, the following terms will have the following
         respective meanings:

         (a)      "Building Grade" shall mean the type, brand and/or quality of
                  materials Landlord designates from time to time to be the
                  minimum quality to be used in the Building or the exclusive
                  type, grade, or quality of material to be used in the
                  Building.

         (b)      "Cable" shall mean only (i) optical fibers encased in an
                  aluminum sleeve, (ii) EMT conduit, (iii) copper cable, or (iv)
                  other materials approved by Landlord. The Cable (or conduit)
                  shall not exceed four inches in diameter.

         (c)      "License Fees" shall mean, collectively, the Service Fee, the
                  Raceway Fee, and the Antenna License Fee as defined in
                  Paragraph 3 of Exhibit "G" attached hereto, and other sums of
                  money becoming due and payable to Landlord hereunder.

         (d)      "License Term" shall mean a term commencing on the
                  Commencement Date and shall expire upon the expiration or
                  earlier termination of the Lease Term, unless sooner
                  terminated pursuant to the provisions of this Exhibit.

         (e)      "Normal Business Hours" for the Building shall mean 8:30 a.m.
                  to 5:00 p.m. Mondays through Fridays, exclusive of normal
                  business holidays.

         (f)      "Raceway" shall mean a vertical and/or horizontal space and
                  pathway within the Project of no more than four inches in
                  diameter (unless a greater size is approved in writing by
                  Landlord) used for routing telecommunications cables and
                  ancillary equipment from Tenant's point of presence in the
                  Building. The precise location of the Raceway applicable to
                  this Telecommunications License will be designated by Landlord
                  and the Telecommunications Equipment (as defined herein) will
                  be installed only as designated by Landlord.

         (g)      "Raceway Fee" shall mean the sum calculated for all installed
                  Cable or conduits from Tenant's point of presence to other
                  locations or customers in the Building at the rates identified
                  in Schedule A per month.

                                       45
<PAGE>
 
         (h)      "Service Fee" shall mean the sum calculated for all installed
                  services from Tenant's point of presence to other locations or
                  customers in the Building at the rates identified in Schedule
                  B.

         (i)      "Telecommunications Equipment" shall mean the Cable, junction
                  boxes, hangers, pull boxes, grounding wiring and related
                  equipment used in the normal course of Tenant's business,
                  which will be installed by Tenant, after approval by Landlord,
                  into the equipment room and Raceway to be used by Tenant,
                  pursuant to the terms of this License.

2.       GRANT OF LICENSE. Subject to and upon the terms set forth in this
         Exhibit, Landlord grants Tenant a license to use the Raceway and to
         install Cable in the Raceway which connects to various tenants of the
         Building on a non-exclusive basis, all as is more particularly
         described in this Exhibit for the purpose of providing access for
         Tenant's Telecommunications Equipment from the Leased Premises to the
         points of entry for the Building ("Telecommunications License"). Tenant
         acknowledges that this Telecommunications License gives Tenant the
         right to provide services to any tenant in the Building listed on
         Schedule C. Landlord specifically reserves the right to contract with
         competitors of Tenant for the same or similar services in the Building
         and acknowledges that it has entered into any such contracts prior to
         the date of this Telecommunications License. Landlord shall have no
         obligation to assist Tenant in marketing its equipment and/or services
         to the Building or to any other property owned by Landlord.

3.       LICENSE TERM. This License shall be in effect during the Lease Term. If
         the Raceway is not available for the commencement of Tenant's
         installation operations by the Commencement Date, due to the omission,
         delay or default of Tenant or of anyone acting under or for Tenant,
         Landlord shall have no liability; and the obligations of Tenant under
         this License (including, without limitation, the obligation to pay
         License Fees shall nonetheless commence as of the Commencement Date.
         Prior to the expiration or earlier termination of this
         Telecommunications License, Tenant shall remove all its
         Telecommunications Equipment that can be removed without causing any
         material damage to the Building and shall surrender and deliver the
         Raceway to Landlord in the same condition in which it existed at the
         Commencement Date, excepting only ordinary wear and tear and damage
         arising from any cause not required to be repaired by Tenant. In the
         event that  Tenant  fails to comply with the terms of this Paragraph 3,
         (i) all such Telecommunications Equipment remaining within the Raceway
         or Building may, at Landlord's option, become the sole property of
         Landlord or (ii) Landlord may, if it so elects, perform any act which
         Tenant is required to perform and/or remove the Telecommunications
         Equipment and other property at Tenant's cost, and Tenant shall pay
         Landlord promptly all costs incurred in removing said property upon
         demand.

4.       USE. The Raceway and mechanical room shall be used solely for the
         installation, operation and maintenance of the Telecommunications
         Equipment and for no other purpose whatsoever. Any use of the Raceway
         for any other purpose or any attempt by Tenant to allow the use or
         occupation of the Raceway by anyone other than Tenant shall,

                                       46
<PAGE>
 
         unless otherwise agreed to by Landlord in writing shall be a default;
         and Landlord shall have the right to immediately terminate this License
         pursuant to the provision of Section 6.1 of the Lease. Tenant shall not
         use or permit the use of the Raceway for any purpose which is illegal,
         dangerous to life, limb or property, or which, in Landlord's reasonable
         opinion, creates a nuisance or which would increase the cost of
         insurance coverage with respect to the Building. In particular, no
         semiconductors or other electronic equipment containing polychlorinated
         biphenyls (PCB's) or other environmentally hazardous materials will
         either be used or stored in or around the Raceway; and no such
         materials will be used in any of the Telecommunications Equipment
         installed by Tenant in the Raceway. Tenant will not permit unauthorized
         persons or persons with insufficient expertise or experience to enter
         any mechanical room in which the Raceway is located to maintain or
         operate its Telecommunications Equipment. Tenant understands that the
         mechanical rooms must be kept locked and secure at all times must not
         be available or open to the public. Landlord may, at Landlord's
         discretion, authorize other licensees and tenants of the Building to
         use portions of the Raceway, or to use portions of other raceways in
         the Building, whether for the installation of telecommunications
         equipment or otherwise, so long as such uses would not require Tenant
         to remove its previously installed Cable from the Raceway. Tenant
         acknowledges that interruptions in utility services are not uncommon in
         facilities such as the Building and that any sensitive electronic
         equipment which may be used in the Raceway should be protected by
         Tenant from utility service interruptions through the use of backup
         power supplies, surge protectors and other appropriate safety systems.

5.       INSTALLATION. The point of presence and network interface will be in
         accordance with the rules and regulations established by (a) Landlord
         and (b) the Public Utility Commission or other governmental authority
         with jurisdiction over such matters in the State of Texas. Each
         horizontal Raceway (including the installation of Cable therein) shall
         be constructed and/or installed at the sole cost and expense of Tenant.
         Tenant shall provide Landlord with a site diagram depicting the
         distribution system to all end users no less frequently than once every
         year and in conjunction with each new service installation. Failure to
         provide such a diagram on a timely basis shall be an event of default.
         Schedule D depicts the Cable  locations in the Raceway and terminal
         points on all floors.  All  specifications, Telecommunications
         Equipment, and Cable will be installed in a good and workmanlike
         manner, and the installation must be approved by Landlord's technical
         representative prior to the commencement of use of the
         Telecommunications Equipment by Tenant. No activities of Tenant
         associated with the construction of the Raceway and the installation of
         the Telecommunications Equipment shall be conducted during Normal
         Business Hours.

6.       LICENSE FEE PAYMENT.

         (a)      The License Fees applicable to Tenant's initial installation
                  of four (4), four inch (4") cables shall be paid to Landlord
                  during the License Term, without any setoff or deduction
                  whatsoever. Except as otherwise provided in this Exhibit, the
                  License Fees for each calendar month or portion thereof during
                  the License Term shall be due and payable in advance on the
                  first day of each month during the

                                       47
<PAGE>
 
                  License Term; and Tenant shall pay such Service Fee and
                  Raceway Fee as provided in Schedule F monthly, in advance, on
                  or before the first day of each calendar month, and without
                  demand. All installments of the License Fees which are not
                  paid when due will bear interest and be subject to a late
                  charge as provided in Section 3.2 of the Lease, and Landlord
                  may exercise the remedies provided in Section 3.3 of the Lease
                  in the event of consecutive late payments of any of the
                  License Fees.

         (b)      Tenant shall keep an accurate set of books and records of all
                  installed service from business conducted in the Building or
                  Raceway, and all supporting records such as, work orders and
                  other records which are necessary to verify and substantiate
                  the amount of Tenant's License Fees at Tenant's business
                  office located in the Premises. All such books and records
                  shall be retained and preserved for at least twenty-four (24)
                  months after the end of the calendar year to which they
                  relate, and shall be subject to inspection and audit by
                  Landlord and its agents at all reasonable times. The
                  acceptance by Landlord of payments of any License Fees shall
                  be without prejudice to Landlord's right to an examination of
                  Tenant's books and records in order to verify the computation
                  of the Raceway Fee and Service Fee provided by Tenant. In the
                  event Landlord is not satisfied with any monthly statement or
                  annual statement submitted by Tenant, Landlord shall have the
                  right to have its auditors make a special audit of all books
                  and records, wherever located, pertaining to sales made in or
                  from the Building or Raceway during the period in question. If
                  such statements are found to be incorrect to an extent of more
                  than two percent (2%) over the figures submitted by Tenant,
                  Tenant shall pay for such audit. Tenant shall promptly pay to
                  Landlord any deficiency or Landlord shall promptly credit to
                  Tenant any overpayment, as the case may be, which is
                  established by such audit.

         (c)      In addition to the License Fees, Tenant shall pay Landlord if,
                  and when due, any sales, use or other taxes or assessments
                  which are assessed or due by reason of this License or
                  Tenant's use of the Building hereunder.

         (d)      Upon each anniversary date of this License, including any
                  renewal term, the License Fees payable by Tenant shall
                  increase as follows and using the following definitions:

                  "Consumer Price Index" - The monthly indexes of the National
                  Consumer Price Index for All Urban Consumers (CPI-U) - All
                  Items, issued by the Bureau of Labor Statistics.

                  "Base Price Index Number" - The Consumer Price Index as of
                  December of the year in which the Commencement Date occurs.

                  "Current Index Number" - The Consumer Price Index as of
                  December of the year in which the calculations are being done.

                                       48
<PAGE>
 
                  If the Current Index Number is greater than the Base Price
                  Index Number, then the "Percentage of Increase" shall be
                  calculated as follows:

                  (Current Index Number - Base Price Index Number) , Base Price
                  Index ' 100 = Percentage of Increase

                  This Percentage of Increase shall be multiplied by the License
                  Fee defined above to obtain the new rate to go into effect on
                  each anniversary of the Commencement Date of this License. The
                  fee increase shall in no case be less than 3.5% annually of
                  the most recent past License Fees amount, as increased. This
                  Percentage of Increase applies to License Fee only and does
                  not apply to any charges in the Base Rent.

7.       CONDITION OF THE RACEWAY. Tenant accepts the Raceway "as is" without
         benefit of any improvements to be constructed or made by Landlord.

8.       MAINTENANCE AND REPAIR BY LANDLORD. Except as otherwise expressly
         provided herein, Landlord shall not be required to make any repairs to
         the Raceway other than repairs to exterior and load-bearing walls of
         the Building, floors of the mechanical rooms (but not to floor
         coverings), and the roof of the Building, which may be required from
         time to time, but only after such required repairs have been requested
         by Tenant in writing. In no event shall Landlord be responsible for the
         maintenance or repair of improvements which are not composed of
         Building Grade materials.

9.       SERVICE AREA ACCESS. Except in the case of an emergency, Tenant shall
         not enter or attempt access to any of the Service Areas (including air,
         electrical, mechanical or telecommunications risers, ducts, closets,
         conduits, duct work, rooms or other horizontal or vertical spaces in
         the Building) without notifying Landlord in writing at least two (2)
         days in advance. In the case of an emergency, Tenant may enter or seek
         access to the Raceway through the Service Areas provided it gives
         Landlord at least two (2) hours prior notice and provided that a
         Building security guard must unlock such Service Area. If Landlord is
         also experiencing an emergency situation in the Building at the same
         time that Tenant has notified Landlord of an emergency, Landlord shall
         have no obligation to first address or respond to Tenant's emergency
         and shall only be obligated to accommodate Tenant's concerns as time
         permits thereafter. Tenant also agrees to furnish Landlord, within two
         (2) business days thereafter, a written report explaining all repairs
         and procedures which were conducted during any such emergency
         operations, in sufficient detail to permit Landlord's engineers to
         evaluate same. Any access to the Service Areas shall require Tenant to
         sign in at the security department console, and Tenant shall permit the
         Landlord's security guard or a representative of Landlord to accompany
         Tenant during any such work within a Service Area, if Landlord so
         desires. No installation, alterations or repairs shall be initiated
         without first delivering to Landlord's engineers plans and
         specifications of the proposed changes,  in substance and form
         acceptable to Landlord.  No oral approval of these plans and
         specifications shall be effective. No electrical grounding shall be
         permitted to other equipment in the mechanical rooms without Landlord's
         specific written approval of the method and location of such grounding.
         No monitoring or inspection of Tenant's work by Landlord's

                                       49
<PAGE>
 
         representatives shall be deemed supervision of Tenant's employees or
         shall be deemed to be a representation or warranty of any particular
         level of telecommunications expertise attained by Landlord's
         representative. Tenant shall monitor and supervise its own employees
         and shall assume responsibility for the expertise and quality of its
         work and shall not rely upon Landlord for same.

10.      NO ACCESS TO OTHER TENANTS' PREMISES. Tenant acknowledges that nothing
         in this License entitles it to enter and connect its Telecommunications
         Equipment to any tenant's premises in the Building without the prior
         written consent of Landlord. Tenant also acknowledges that it has been
         informed that telecommunications connections to individual tenant's
         premises in the Building will normally require removal of ceiling
         panels, at each tenant's expense, with such removal operations only
         being performable by Landlord's agents or employees.

11.      LICENSES AND PERMITS. Prior to commencing any work on the Raceway,
         Tenant shall obtain all necessary licenses, permits and consents and
         provide copies of same to Landlord. Landlord shall have the right to
         monitor all such work, at its own expense.

12.      COSTS. Tenant shall be responsible for any and all cost, damage or
         expense arising from the installation, maintenance, or repair to the
         Raceway or the Telecommunications Equipment, including, without
         limitation, any and all cost, damage or expense to the Building or the
         property of Landlord or other licensees or tenants of the Building
         arising from such installation, maintenance or repair operations.
         Tenant will make any and all repairs necessary in a timely manner. If
         Tenant does not make required repairs to Landlord's satisfaction within
         twenty-four (24) hours of notification from Landlord that said repairs
         are necessary within a tenant's space or within ten (10) days of
         notification from Landlord that said repairs are necessary pursuant to
         Paragraph 13 of this Exhibit, then Landlord will have the right but not
         the obligation to perform any such repairs at Tenant's sole cost and
         expense. Tenant shall on demand pay to Landlord as additional License
         Fees (i) the cost of such work plus fifteen percent (15%) thereof as
         administrative costs; plus (ii) interest thereon at the rate of 12% per
         annum from the date of demand.

13.      MAINTENANCE, REPAIRS, AND ALTERATIONS BY TENANT. Tenant shall not
         commit any waste or allow any waste to be committed within or on any
         portion of the Raceway or in any Service Area and will maintain the
         Raceway in a clean, attractive condition and in good repair. At the
         termination of this License, Tenant agrees to deliver up the Raceway to
         Landlord in as good condition as at the Commencement Date, ordinary
         wear and tear and damage by casualty excepted (unless caused by
         Tenant). Tenant will remove all excess cable, tools, and equipment and
         will keep all areas neat and clean at all times. Landlord shall have
         the right, at its option, at Tenant's own cost and expense, to repair
         or replace any damage done to the Building, or any part thereof, caused
         by Tenant (or by any Affiliate, contractor, agent, or employee of
         Tenant), and Tenant shall pay the reasonable cost thereof to Landlord
         on demand as additional License Fees. Tenant shall not make or allow
         any alterations to the Raceway without the prior written consent of
         Landlord. Tenant shall not place signs on any of the doors or corridors

                                       50
<PAGE>
 
         leading to the Raceway, without first obtaining the prior written
         consent of Landlord in each such instance, which consent may be given
         or arbitrarily withheld on such conditions as Landlord may elect.
         Landlord shall have the right, at its option, at Tenant's own cost and
         expense, to remove any signs placed by Tenant without Landlord's prior
         written consent, and to repair any damage caused by the such signs. Any
         and all alterations to the Raceway shall become the property of
         Landlord upon termination of this License.

14.      USE OF ELECTRICAL SERVICES BY TENANT. All electrical usage associated
         with the Telecommunications Equipment will be governed by the
         provisions of Section 4.3 of the Lease.

15.      LAWS AND REGULATIONS. Tenant shall comply with all Legal Requirements
         and Insurance Requirements and shall, at Tenant's sole cost, take all
         measures necessary to assure that the Telecommunications Equipment
         strictly complies with all Legal Requirements and Insurance
         Requirements. Tenant shall also pay promptly when due all royalties or
         other fees due in connection with the operation of the
         Telecommunications Equipment. In the event compliance with this
         paragraph shall require modifications or alterations of the
         Telecommunications Equipment or the Raceway, no modification or
         alteration shall be made without Landlord's prior written consent,
         which consent may be withheld in Landlord's sole judgment or granted on
         such terms and conditions as Landlord may determine in its sole
         judgment. Tenant shall take all measures necessary to assure that the
         Telecommunications Equipment does not interfere with or disturb the
         operation of any other equipment or business of Landlord or of any
         other licensee, tenant, or occupant of the Building.

16.      SITE TECHNICAL STANDARDS. Tenant will strictly comply with the Site
         Technical Standards (Schedule E) as adopted and altered by Landlord
         from time to time and will cause all of the Tenant Related Parties to
         do so. All changes to such standards will be sent by Landlord to Tenant
         in writing.

17.      ENTRY BY LANDLORD. Tenant shall permit Landlord or its employees,
         agents, contractors, or representatives to have access to any portion
         of the Raceway at all times to inspect the same, to clean or make
         repairs, alterations or additions thereto, and Tenant shall not be
         entitled to any abatement or reduction of License Fees by reason of any
         such entry.

18.      INDEMNIFICATION. In addition to the indemnification obligations of
         Tenant under the Lease, Tenant shall protect, defend, indemnify, and
         hold Landlord harmless from all liability and claims for any injury to
         person or damage to property caused by any act, omission, or neglect of
         Tenant, its agents, servants, employees, or contractors, relative to
         the Telecommunications License, including, without limitation, the
         installation, operation, repair, and maintenance of the
         Telecommunications Equipment.

19.      DAMAGE. Landlord shall not be liable to Tenant for any loss or damage
         to all or any part of the Telecommunications Equipment occasioned by
         theft, fire, act of God, public

                                       51
<PAGE>
 
         enemy, injunction, riot, vandalism, malicious mischief, earthquake,
         flood, strike, insurrection, war, court order, requisition, or order of
         governmental body or authority, or by any other cause whatsoever. Nor
         shall Landlord be liable for any damage or inconvenience which may
         arise through the repair or alteration of any part of the Building or
         through termination of the Telecommunications License. Further,
         Landlord shall not be liable for any damage which may arise through the
         repair or alteration of any part of the Building or through termination
         of this Telecommunications License other than damage caused by the
         gross negligence or willful misconduct of Landlord, its agents or
         employees.

20.      INSURANCE. In addition to the insurance obligations of Tenant under the
         Lease, Tenant shall maintain a policy or policies of fire and extended
         coverage insurance on the Telecommunications Equipment, in such amounts
         as Tenant may deem appropriate; provided, however, that Tenant shall
         never have any claim against Landlord for any loss or damage that may
         occur to the "Antenna Equipment" (as defined in Exhibit "G") which
         could be covered by insurance.

21.      TRANSFERS BY TENANT. Tenant shall not assign, convey, mortgage, pledge,
         hypothecate, encumber, or otherwise transfer the Telecommunications
         License or grant any license, concession, or other right with respect
         to the Telecommunications License without the prior written consent of
         Landlord, which consent may be granted or withheld in Landlord's sole
         discretion. In addition, the Telecommunications License shall
         terminate, in Landlord's sole discretion, upon the assignment of the
         Lease or a subletting of the Premises, unless such transfer is to an
         Affiliate of Tenant in connection with an assignment or sublease to an
         Affiliate as provided in Section 4.7 of the Lease.

22.      DEFAULT BY TENANT. In addition to provisions of Articles 8 and 6 of the
         Lease, Tenant shall be deemed to be in default with respect to the
         Antenna License in the event that (a) Tenant shall fail to pay the
         Telecommunications License Fees when due; or (b) Tenant shall fail to
         maintain the Telecommunications Equipment in good order and repair and
         in a safe condition as provided in this Exhibit; or (c) Tenant shall
         fail to maintain all necessary licenses and permits with respect to the
         operation of the Telecommunications Equipment. Upon a default by Tenant
         with respect to the Telecommunications License, Landlord may, at
         Landlord's sole election, pursue the remedies granted to Landlord for
         default under the Lease or, in the alternative, terminate the
         Telecommunications License granted hereunder without terminating the
         Lease or terminating Tenant's right to possession of the Premises under
         the Lease.

23.      SURVIVAL. Certain provisions of this Exhibit relate to the rights and
         obligations of Landlord and Tenant subsequent to the termination or
         expiration of the Lease Term. Such provisions include, without
         limitation, the restoration obligations of Tenant under Paragraph 13
         hereof and the indemnification obligations of Tenant under Paragraph 19
         hereof. Such provisions shall survive the expiration or other
         termination of the Lease Term and the Telecommunications License
         granted to Tenant hereunder.



                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       52
<PAGE>
 
                                   SCHEDULE A
                                   ----------

      To Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- --------------------------------------------------------------------------------

                                   RACEWAY FEE

Monthly charges for the initially installed three (3) for fee and one (1) for
free 4" conduits are included in the Base Rental.

Any additional Raceway Fees for conduits shall mean the total installed conduits
of conductors at the following rates:
<TABLE>
<CAPTION>
         SIZE                               up to .5"  .5 to 1"  1 to 1.5"  1.5 to 2"  2 to 2.5"  2.5 to 4"  Over 4"
         <S>                                <C>        <C>       <C>        <C>        <C>        <C>        <C>
         $/linear foot horizontal           $0.10      $0.20     $0.30      $0.40      $0.75      $1.00      Quote
         $/linear foot horizontal           $0.15      $0.30     $0.45      $0.60      $1.13      $1.50      Quote
                  (out of Building)
         $/linear foot vertical (12'min)    $1.00      $2.00     $3.00      $4.00      $7.50      $10.00     Quote
</TABLE>

per month.

Discount based on Rentable Square Feet:

0-10,000                    0%
10,001-20,000               5%
20,001-30,000              10%
30,001-40,000              15%
40,001-50,000              20%



                                       53
<PAGE>
 
                                   SCHEDULE B
      To Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                                  SERVICE FEE


The Service Fee shall mean the total installed services at the following rates:

                           a. DS-O = Zero Dollars per month,
                           b. DS-1 = Zero Dollars per month, and
                           c. DS-3 = Zero Dollars per month

                                       54
<PAGE>
 
                                   SCHEDULE C

      To Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

              List of Tenants to Whom Licensee May Provide Services


                                       55
<PAGE>
 
                                   SCHEDULE D

      To Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                  Telecommunications Equipment Systems Diagram



    This schematic describes the telecommunications equipment systems to be
       installed for the limited purpose of the license described herein.


                                       56
<PAGE>
 
                                   SCHEDULE E

      To Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                            Site Technical Standards

                  1. The fiber transmission cables and all copper telephone
                  cables must be Teflon (or of City approved fire retardant
                  material) jacketed type cable, and secured by either stainless
                  steel clamps or approved equal when not run in EMT type
                  conduit. Excess transmission line must be removed.

                  2. Each fiber or copper telephone line or conduit shall be
                  identified with stainless steel tags that identifies the
                  user/Licensee: (1) at the equipment cabinet; (2) at each side
                  of horizontal/vertical penetration (3) as the line traverses
                  the Building at a minimum of 72' intervals, coincident with
                  column lines, and (4) at the termination point(s).

                  3. The location and installation of all equipment and conduit
                  will be designated by the site coordinator. These locations
                  will be shown on the License. Changes must be approved in
                  writing by the site coordinator. Any conduit or cable failing
                  to meet the above standards will be immediately removed from
                  the Building at Licensee's expense. In the event Licensee
                  fails to promptly remove any such conduit or cable, Licensor
                  may do so at Licensee's expense.

                  4. On a 24-hour notice, the Site Equipment will be made
                  available for inspection by the site coordinator to assure
                  compliance with the above standards.

                  5. The following information is essential for site
                  coordination and must be provided. Any and all changes must
                  have prior approval and be reported to the site coordinator.

                           A.       Manufacturer and model number of all end
                                    equipment.

                           B.       Type and length of all cable and lines.

                           C.       The name, address and telephone number of
                                    the person or group directly responsible for
                                    the day-to-day maintenance.

                           D.       The name, address and telephone number of
                                    the person or group directly responsible for
                                    the License Agreement.

                                   SCHEDULE F
     To  Exhibit F to Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                           Calculation of License Fee

                                       57
<PAGE>
 
         The License Fee shall be paid in monthly installments pursuant to
         Paragraph 6 of the License. The License Fee shall be equal to:

                  1.  The Service Fee, plus

                  2.  The Raceway Fee, plus

                  3.  The Satellite/Antenna Fee.

         This License Fee does not include construction costs, installation
         costs, utilities or any other costs associated with occupancy and
         operation in the Building.




                                       58
<PAGE>
 
                                   EXHIBIT "G"

            To Lease Agreement By and Between INFOMART-Dallas L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                            SATELLITE/ANTENNA LICENSE
                            -------------------------

This Exhibit "G" describes the license to install certain specified
satellite/antenna communications equipment upon the roof of the Building which
is being granted by Landlord to Tenant upon the following terms and conditions:

1.       DEFINED TERMS. For purposes of this Exhibit, all terms defined in this
         Lease (including other exhibits in this Lease) will be used in this
         Exhibit without further definition. In addition, other terms which are
         defined in this Exhibit will, when delineated with initial capital
         letters, have the respective meanings specified in this Exhibit.

2.       GRANT OF LICENSE. Subject to the terms and provisions of this Exhibit,
         Landlord grants to Tenant a license ("Antenna License") to maintain a
         satellite antenna dish together with related wiring and equipment
         (collectively, the "Antenna Equipment") on the roof of the Building.
         The term of the Antenna License shall commence on the Commencement Date
         and shall terminate upon the expiration or the earlier termination of
         the Lease Term, unless sooner terminated pursuant to the provisions of
         this Exhibit. The size, location, and manner of installation of the
         Antenna Equipment shall be determined at Landlord's sole discretion,
         which discretion will take into consideration (a) the functional
         requirements of the Antenna Equipment and of any other satellite
         antenna dishes located on the roof of the Building and (b) standards of
         architectural integrity with respect to the Building (and, in that
         regard, the Antenna Equipment shall be located so as not to be visible
         except from above the Building, shall match the Building color, and
         shall have no visible marking or logo). The Antenna License shall
         commence on the Commencement Date and shall expire upon the expiration
         or earlier termination of the Lease Term.

3.       ANTENNA LICENSE FEE. The Antenna License Fee allowed by this Exhibit is
         One Hundred Ten and 59/100ths Dollars ($110.59) . License Fees will not
         go into effect until the later of the Rental Commencement Date or the
         commencement of construction for such antenna. Additional satellite
         dishes shall be at a fee of one hundred fifty (150) percent of the
         established initial Satellite/Antenna Fee. The Antenna License Fee
         includes the connection of the Antenna Equipment to Tenant's
         Telecommunications Equipment in the Leased Premises, and no additional
         fees will be charged for the use of a raceway to make such connection.

4.       INSTALLATION, MAINTENANCE, AND REPAIR. Tenant shall, at Tenant's sole
         cost and expense, provide for the installation of the Antenna Equipment
         and for all service, repairs, and maintenance to the Antenna Equipment.
         With respect to the installation of the Antenna Equipment, the Antenna
         Equipment shall not be affixed to the

                                       59
<PAGE>
 
         roof of the Building by nail, bolt, screw, or other device which
         penetrates the roof; and all wiring penetrations shall be made by
         Landlord's roofing contractor at Tenant's sole cost and expense. The
         Antenna Equipment shall be maintained by Tenant in good order and
         repair and in a safe condition. In the event that Tenant fails to
         maintain the Antenna Equipment and Landlord, in Landlord's sole
         judgment, determines that such failure presents a danger of injury to
         persons or damage to property in or about the Building. Landlord may,
         after prior written notice to Tenant (except in the event of
         emergencies) (but without being under any obligation to do so) arrange
         for such repairs or maintenance to be done and recover the cost
         incurred from Tenant. Any such sums shall be due and payable by Tenant
         on demand. Tenant shall provide Landlord with prior written notice of
         Tenant's need to service, maintain, or repair the Antenna Equipment.
         Landlord shall then provide Tenant with access to the roof of the
         Building and other non-tenant areas of the Building at such times and
         under such conditions as may be reasonably determined by Landlord.
         Landlord may charge Tenant for any of Landlord's equipment and material
         used by Tenant and any time spent by Landlord, Landlord's management
         staff, or Landlord's consultants arising out of Tenant's failure to
         properly maintain or repair the Antenna equipment. In that regard, the
         Antenna Equipment shall be of a type so as to constitute a permanent,
         as opposed to a temporary, installation.

5.       INTERFERENCE. Tenant shall modify the Antenna Equipment or relocate the
         Antenna Equipment to another area approved by Landlord in the event
         that the Antenna Equipment, in Landlord's sole judgment, causes any
         interference with or disturbs the operation of any other antenna
         equipment or business of Landlord or of any other occupants of the
         Building or creates or results in any noise, odor, or nuisance to any
         other occupant of the Building, or areas adjacent to the Building.
         Tenant must immediately shut off the Antenna Equipment upon
         notification of interference and may restart, modify, or relocate the
         Antenna Equipment to test for interference only with Landlord's
         permission.

6.       USE. The Antenna Equipment shall be designed, installed, and operated
         solely for the purpose of passive receptions of transmissions and is
         solely for use in Tenant's internal business. The benefits of the
         Antenna Equipment may not be provided by Tenant to third parties. The
         Antenna Equipment may not be sold or rented by Tenant to third parties,
         nor may Tenant sublet or assign this License. Tenant shall operate the
         Antenna Equipment in compliance with all Legal Requirements and
         Insurance Requirements and shall maintain all necessary licenses and
         permits with respect to its operation of the Antenna Equipment. Any
         electrical usage associated with the Antenna Equipment shall be
         governed by the provisions of Section 4.3 of the Lease.

7.       INTERRUPTION. Landlord may, at Landlord's sole discretion but without
         cost to Landlord, after prior written notice to Tenant (except in the
         event of emergencies), require interruption of service or relocation or
         removal of the Antenna Equipment for repairs, maintenance, or
         modifications to the Building, including, but not limited to, roofing,
         structural, electrical, or mechanical repairs. Landlord shall use
         reasonable efforts not to interfere with Tenant's business.

                                       60
<PAGE>
 
8.       MODIFICATION AND SUBSTITUTION. Tenant may not substitute or modify the
         Antenna Equipment or any part thereof, without the prior written
         approval of Landlord. Any substitution or modification approved by
         Landlord shall automatically become a part of the Antenna Equipment,
         and all terms of this Exhibit shall apply to such substitution and/or
         modification.

9.       RESTORATION. Tenant shall, at Tenant's sole cost and expense, remove
         the Antenna Equipment and restore the Building to its currently
         existing condition upon the termination or expiration of the Lease
         Term, and/or this Antenna License. Such removal and restoration work
         shall be completed by Tenant within thirty (30) days of the date on
         which the condition requiring such removal and restoration work occurs.
         In the event that Tenant fails to complete the removal of the Antenna
         Equipment and the restoration of the Building within such thirty (30)
         day period, Landlord shall have the right (but without any obligation
         to do so) to remove the Antenna Equipment and restore the Building, in
         which event, Tenant shall reimburse Landlord for all costs incurred by
         Landlord in performing such removal and restoration work on demand. In
         addition, any Antenna Equipment remaining at the Building subsequent to
         the expiration of such thirty (30) day period and upon prior written
         notice to Tenant's last known address, shall be deemed to have been
         abandoned by Tenant, so that in no event shall Landlord have any duty
         to preserve or restore the Antenna Equipment on Tenant's behalf. If
         Landlord does choose to store the Antenna Equipment on Tenant's behalf,
         the cost of storage incurred by Landlord shall be reimbursed by Tenant
         on demand. In such event, Landlord shall also have the right to sell
         such Antenna Equipment for salvage value and to apply the proceeds
         derived from such sale to sums owing by Tenant to Landlord under this
         Lease (including this Exhibit). The provisions of this Paragraph 9
         shall survive the expiration of this Antenna License and of the Lease
         Term.

10.      REPRESENTATIONS OF TENANT. As a material inducement to Landlord to
         grant the Antenna License to Tenant, Tenant hereby represents and
         warrants to Landlord that (a) the Antenna Equipment has received
         approval from the Underwriters Laboratory and from the Federal
         Communications Commission; (b) the Antenna Equipment will be installed
         in accordance with the plans and specifications approved by Landlord,
         in Landlord's sole discretion; (c) the Antenna Equipment is designed to
         require minimum maintenance; (d) the Antenna Equipment will not
         interfere with other like antenna equipment located on the rooftop of
         the Building or in the Building; and (e) Tenant will have received all
         necessary licenses and permits from all applicable governmental
         authorities regarding the installation and operation of the Antenna
         Equipment, prior to such installation and operation.

11.      INDEMNIFICATION. In addition to the indemnification obligations of
         Tenant under the Lease, Tenant shall protect, defend, indemnify, and
         hold Landlord harmless from all liability and claims for any injury to
         person or damage to property caused by any act, omission, or neglect of
         Tenant, its agents, servants, employees, or contractors, relative to,
         or arising in connection with, the Antenna License, including, without
         limitation, the installation, operation, repair, and maintenance of the
         Antenna Equipment.

                                       61
<PAGE>
 
12.      DAMAGE. Landlord shall not be liable to Tenant for any loss or damage
         to all or any part of the Antenna Equipment occasioned by theft, fire,
         act of God, public enemy, injunction, riot, vandalism, malicious
         mischief, earthquake, flood, strike, insurrection, war, court order,
         requisition, or order of governmental body or authority or by any other
         cause whatsoever. Further, Landlord shall not be liable for any damage
         or inconvenience which may arise as a result of the repair or
         alteration of any part of the Building or through termination of the
         Antenna License, other than damage caused by the gross negligence or
         willful misconduct of Landlord, its agents or employees.

13.      INSURANCE. In addition to the insurance obligations of Tenant under the
         Lease, Tenant shall maintain a policy or policies of fire and extended
         coverage insurance on the Antenna Equipment, in such amounts as Tenant
         may deem appropriate; provided, however, that Tenant shall never have
         any claim against Landlord for any loss or damage that may occur to the
         Antenna Equipment which could be covered by insurance.

14.      TRANSFERS BY TENANT. Tenant shall not assign, convey, mortgage, pledge,
         hypothecate, encumber, or otherwise transfer the Antenna License or
         grant any license, concession, or other right with respect to the
         Antenna License without the prior written consent of Landlord, which
         consent may be granted or withheld in Landlord's sole discretion,
         unless such transfer or assignment is to an Affiliate in connection
         with Tenant's transfer of the Lease to an Affiliate pursuant to Section
         4.7 of the Lease. In addition, the Antenna License shall terminate, in
         Landlord's sole discretion, upon the assignment of the Lease or a
         subletting of the Premises, except as provided in Section 4.7.

15.      DEFAULT BY TENANT. In addition to provisions of Article 8 of the Lease,
         Tenant shall be deemed to be in default with respect to the Antenna
         License in the event that (a) Tenant shall fail to maintain the Antenna
         Equipment in good order and repair and in a safe condition as provided
         in this Exhibit; or (b) Tenant shall fail to maintain all necessary
         licenses and permits with respect to the operation of the Antenna
         Equipment. Upon a default by Tenant with respect to the Antenna
         License, Landlord may, at Landlord's sole election, pursue the remedies
         granted to Landlord for default under the Lease or, in the alternative,
         terminate the Antenna License granted hereunder without  terminating
         the Lease or terminating Tenant's right to possession of the Premises
         under the Lease.

16.      SURVIVAL. Certain provisions of this Exhibit relate to the rights and
         obligations of Landlord and Tenant subsequent to the termination or
         expiration of the Lease Term. Such provisions include, without
         limitation, the restoration obligations of Tenant under Paragraph 9
         hereof and the indemnification obligations of Tenant under Paragraph 11
         hereof. Such provisions shall survive the expiration or other
         termination of the Lease Term and the Antenna License granted to Tenant
         hereunder.


                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       62
<PAGE>
 
                                   EXHIBIT "H"
                                   -----------

            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                                    GENERATOR
                                    ---------

This Exhibit "H" describes and specifies Tenant's use of additional areas in the
Building and on the Property for purposes of the installation and operation of
Tenant's Generator, upon the following terms and conditions:

1.       DEFINED TERMS. For purposes of this Exhibit "H", all terms defined in
         the Lease (including other Exhibits to the Lease) will be utilized
         herein without further definition. In addition, when delineated with
         initial capital letters, the following terms shall have the following
         respective definitions and meanings:

         a.       "Cable" shall mean only optical fibers, copper wires (also
                  known as "copper pairs"), coaxial cable, and other similar
                  transmission wiring customarily used in the industry, unless
                  other materials are expressly approved in writing by Landlord.

         b.       "Conduit" shall mean a plastic or metal sleeve, no more than
                  4" in aggregate diameter, unless a larger size is expressly
                  approved by Landlord in writing, in which Cable is encased
                  and/or through which Cable passes.

         c.       "Generator" shall mean the 750KW generator with automatic
                  transfer switch and load bank equipment to be installed by
                  Tenant on the 8 foot by 16 foot pad at the location designated
                  on Schedule "1" attached to this Exhibit.

         d.       "Tank" shall mean the 2,000 gallon fossil fuel tank and
                  associated transfer pumps to be installed by Tenant at the
                  location designated on Schedule "1" attached to this Exhibit.
                  The term "Tank" shall also be deemed to include the fuel oil
                  pipes to be installed by Tenant from the Tank to the
                  Generator. The Tank must have self-contained spill and leak
                  control features, it must be installed in a secure and safe
                  location above-ground, and it must conform to all legal
                  requirements concerning tank tightness, spill control and
                  monitoring features required by state and federal laws.

         e.       "Equipment" shall mean the Cable, Conduit, junction boxes,
                  hangers, pull boxes, grounding wiring and related equipment
                  used in the normal course of Tenant's business, which will be
                  installed by Tenant into the Leased Premises and into the
                  Raceway to be utilized by Tenant, pursuant to the terms
                  hereof.

                                       63
<PAGE>
 
2.       GRANT OF LICENSE. Landlord grants Tenant a license, subject to the
         terms and conditions herein, to (i) use such locations on the Property
         as are approved in writing by Landlord in order for Tenant to install
         Tenant's generator cabling to, and core drilling of, the Building core
         structural wall (it being acknowledged that Landlord has made no
         representation that Tenant will be able to utilize any Southwestern
         Bell or other utility easements in this regard) and use such Raceways
         as are approved in writing by Landlord in order for Tenant to install
         its Generator cabling from the Generator to the points of entry at the
         Building core structural wall to the Leased Premises, (ii) use such
         Raceways as are approved in writing by Landlord for the purpose of
         Tenant's installing, maintaining, repairing, replacing and operating
         the Equipment, (ii) use the designated location of the Generator for
         the purpose of installing, maintaining, repairing and operating the
         Generator, and (iii) use the designated location of the Tank for the
         purpose of installing, maintaining, repairing and operating the Tank.

3.       LICENSE TERM. The term of this license shall be coterminous with the
         Lease Term and shall continue in force during a period beginning on the
         Commencement Date and continuing until the expiration or earlier
         termination of the Lease Term.

4.       USE. Any Raceway to be utilized by Tenant pursuant to the terms hereof
         shall be used for the installation, maintenance, repair, replacement
         and operation of the Equipment as provided herein and for no other
         purpose. Tenant agrees not to use or permit the use of any such Raceway
         for any purpose which is illegal, dangerous to life, limb or property
         or which, in Landlord's reasonable opinion, creates a nuisance or which
         would increase the cost of insurance coverage with respect to the
         Building. In particular, no semiconductors or other electronic
         equipment containing polychlorinated biphenyls (PCB's) or other
         environmentally hazardous materials will either be used or stored in or
         around the Leased Premises or any such Raceway and no such materials
         will be used in any of the Equipment installed by Tenant in the Leased
         Premises or any such Raceway. Tenant will not permit any unauthorized
         person or persons with insufficient expertise or experience to enter
         the Raceways or maintain or operate the Equipment. Nothing herein
         should be construed as permitting Tenant to use any Raceway for a
         purpose not specifically described herein, or to install new or
         substitute Cable or Conduit into a Raceway which consists of materials
         other than those defined in Paragraph 1 hereof. It is also acknowledged
         that Landlord may, at Landlord's discretion, authorize other tenants
         and licensees of the Building to use portions of any Raceways or risers
         in the Building, whether for the installation of telecommunications
         equipment or otherwise, so long as such uses would not require Tenant
         to remove its Cable or Conduit, which has already been installed by
         Tenant, from such Raceway. Tenant acknowledges that interruptions in
         utility services are not uncommon in facilities such as the Building
         and Tenant acknowledges that any sensitive electronic equipment which
         may be used in the Leased Premises or a Raceway will be protected by
         Tenant from utility service interruptions through the use of the
         Generator and other backup power supplies, surge protectors and other
         safety systems. Tenant acknowledges that it has taken all precautionary
         steps it deems necessary to protect such equipment in the Leased
         Premises and in any Raceway, including the acquisition of insurance if
         applicable. Tenant agrees to release Landlord from any damages or
         losses (including attorney's fees and expenses) sustained to any of

                                       64
<PAGE>
 
         Tenant's Equipment as a result of utility service interruptions, unless
         solely caused by the gross negligence or willful misconduct of
         Landlord, its employees and agents, and agrees to indemnify, defend and
         hold Landlord harmless from any damages or losses (including attorneys'
         fees and expenses) caused by Tenant's Equipment as a result of utility
         service interruptions, unless such interruptions arise primarily by
         reason of the negligence or willful misconduct of Landlord, its agents
         or employees. This release and indemnity is in addition to and not in
         substitution of any other release and indemnity in the Lease.

5.       ADDITIONAL TERMS OF LICENSE. The license granted herein to Tenant shall
         additionally be subject to and expressly conditioned upon the
         following:

         a.       Construction of Raceways. Tenant shall install its generator
                  cabling and the other Equipment, including the Conduit and all
                  necessary Raceways, to the extent not already in place, in the
                  Building at Tenant's sole cost and expense and shall provide
                  Landlord with "as-built" drawings and specifications of same.

         b.       HVAC and Mechanical Room Access. Except in the case of an
                  emergency, Tenant shall not enter or attempt access to any of
                  the Building's air, electrical, mechanical or
                  telecommunications risers, ducts, closets, Conduits, duct
                  work, rooms, Raceways, or other horizontal or vertical spaces
                  in the Building, including the Service Areas, without
                  notifying Landlord in writing at least two (2) days in
                  advance. In the case of an emergency, Tenant may enter or seek
                  access to a Raceway utilized by Tenant pursuant to the terms
                  hereof through mechanical rooms or Service Areas provided
                  Tenant gives Landlord at least two (2) hours prior written
                  notice and provided further that a Building security guard or
                  engineer must unlock and accompany Tenant's employees into
                  such Service Areas and mechanical rooms; if Landlord is also
                  experiencing an emergency situation in the Building at the
                  same time that Tenant has notified Landlord of an emergency,
                  Landlord shall have no obligation to first address or respond
                  to Tenant's emergency and shall only be obligated to
                  accommodate Tenant's concerns as time permits thereafter.
                  Tenant also agrees to furnish Landlord, within two (2)
                  business days thereafter, a written report explaining all
                  repairs and procedures which were conducted  during any such
                  emergency operations, in sufficient detail to permit
                  Landlord's engineers to evaluate the same. Any access to the
                  Building mechanical rooms, whether during an emergency or
                  otherwise, shall require Tenant to sign in at the Building
                  manager's office or the security desk, and Tenant shall permit
                  the Building manager's security guard or representative of
                  Landlord of the Building manager to accompany Tenant during
                  any such mechanical room, if Landlord so desires. No
                  installation, alterations or repairs shall be initiated
                  without first delivering to Landlord's engineers, plans and
                  specifications of the proposed changes, in substance and form
                  acceptable to Landlord. No oral approval of these plans and
                  specifications shall be deemed effective; only evidence of
                  written approval which has been received by Landlord's
                  Building manager will be binding against Landlord. No
                  electrical grounding shall be permitted to other equipment in
                  the mechanical rooms without Landlord's specific written
                  approval of the method and locations of such grounding.

                                       63
<PAGE>
 
         c.       Insurance; Mechanic's Liens. No construction, alteration or
                  removal operations shall be initiated by Tenant hereunder
                  unless Tenant has first obtained workers compensation and
                  builders risk insurance in limits acceptable to Landlord. Any
                  construction or mechanic's liens filed or claimed against the
                  Leased Premises, any Raceway or the Building as a result of
                  Tenant's operations shall be immediately paid, released or
                  bonded over in a manner acceptable to Landlord.

         d.       Hours of Operations. No activities of Tenant associated with
                  the construction and the installation of the Equipment shall
                  be conducted during the normal business hours of the Building.

         e.       Licenses and Permits. Prior to commencing any work on and/or
                  installations hereunder in the Leased Premises, at the
                  locations of the Generator and Tank, or of any Raceway, Tenant
                  shall obtain all necessary licenses, permits and consents and
                  provide copies of the same to Landlord. Landlord shall have
                  the right to supervise all such work, at its own expense.

         f.       Generator License Fee. The license fee for the one (1)
                  Generator allowed by this Exhibit is included in the Base
                  Rental. Additional pads may be added with the approval of
                  Landlord (the size and location of which will be at Landlord's
                  sole option) and the Generator License Fee will be at the then
                  current Landlord's charge for each such additional pad.

         g.       Costs. Licensee shall be responsible for any and all costs,
                  damages or expenses arising from the installation,
                  maintenance, or repair to any Raceway utilized by Tenant
                  pursuant to the terms hereof, the Leased Premises or the
                  Equipment, the Generator or the Tank and any and all costs,
                  damages or expenses to the Building or the property of
                  Landlord or other licensees or tenants of the Building arising
                  from such installation, maintenance or repair operations.
                  Tenant agrees to indemnify and hold Landlord harmless from and
                  against any loss, cost, damage or expense arising out of or in
                  connection with Tenant's installation, maintenance, repair or
                  operation of the Equipment, the Generator or the Tank, unless
                  such loss, cost, damage or expense arises primarily from the
                  negligence or willful misconduct of Landlord, its agents or
                  employees. This indemnity is in addition to and not in
                  substitution of any other indemnity in the Lease. Tenant shall
                  also pay all ad valorem taxes attributable to the Equipment,
                  the Generator and the Tank.

6.       CARE OF GENERATOR, TANK AND RACEWAYS BY TENANT. Tenant agrees not to
         commit any waste or allow any waste to be committed on the areas where
         the Generator and the Tank are located or in any of the mechanical or
         equipment rooms in which any Raceway utilized by Tenant pursuant to the
         terms hereof is located. At the termination of this license, Tenant
         agrees to deliver the areas on which the Generator and Tank are located
         and each Raceway to Landlord in as good condition as at the date of
         this Lease, subject to ordinary wear and tear and damages, fire, and
         other casualties caused by any third parties not affiliated with
         Tenant, its agents, employees or contractors.

                                       66
<PAGE>
 
7.       REPAIRS AND ALTERATIONS BY TENANT. Landlord shall have the right, at
         its option, and at Tenant's cost and expense, to repair or replace any
         damage done to the Building or the Property, or any part hereof, caused
         by Tenant or Tenant's agents, employees, invitees, or visitors, and
         Tenant shall pay the reasonable cost thereof to Landlord on demand as
         additional rent. Tenant agrees with Landlord not to make or allow to be
         made any alterations to any Raceway without the prior written consent
         of Landlord, other than routine Cable installation operations in a
         Raceway utilized by Tenant pursuant to the terms hereof, but even
         routine Cable installations shall not be permitted without prior
         written notice of at least two (2) days to Landlord. Any and all
         alterations to any Raceway shall become the property of Landlord upon
         termination of this license, except for the Equipment installed by
         Tenant. All of the Equipment, the Generator and the Tank (but not the
         Conduit) shall be removed by Tenant from the Leased Premises, the
         Building and the Property immediately upon termination of the license
         in compliance with the provisions of Section 4.4 of the Lease. Tenant
         shall be responsible for repairing any damage to the Leased Premises,
         any Raceway, the Building and/or the Property resulting from the
         removal of any Equipment, the Generator, the Tank or other personal
         property, and Tenant shall be responsible for restoring the Leased
         Premises, any Raceway, the Building and/or the Property, as applicable,
         to good condition. If Tenant fails to remove the Equipment, the
         Generator, the Tank or any other property required to be removed
         herein, Landlord may, if Landlord so elects, remove the Equipment, the
         Generator, the Tank and any other property at Tenant's cost and Tenant
         shall pay Landlord promptly upon demand all costs in removing said
         property.

8.       LAWS AND REGULATIONS. Tenant agrees to comply with all applicable laws,
         ordinances, rules and regulations of any governmental entity or agency
         having jurisdiction with respect to the Equipment, the Generator and
         the Tank, specifically including, without limitation, all applicable
         environmental laws. In particular, prior to installation of the
         Equipment, Tenant shall provide Landlord written evidence, satisfactory
         to Landlord in its sole discretion, of the representations and
         warranties set forth in this Paragraph 8. The parties  acknowledge that
         the Equipment should emit no amounts of radiation whatsoever. Tenant
         shall, at Tenant's sole cost, take all measures necessary to insure
         that no radiation is emitted from the Equipment and that the Equipment,
         the Generator and the Tank strictly complies with all laws, rules,
         regulations, ordinances and codes, whether now or hereafter existing,
         of all federal, state and local governmental authorities and that the
         Equipment strictly complies with all contractual obligations to which
         Tenant is bound in connection with such Equipment, specifically
         including, without limitation, regulations of the Federal
         Communications Commission, the Environmental Protection Agency, and the
         Occupational Safety and Health Administration, applicable to the
         emission of radiation from active transmission equipment or similar
         facilities. Tenant shall also pay promptly when due all royalties or
         other fees due in connection with the operation of the Equipment. In
         the event compliance with this paragraph shall require modifications or
         alteration of the Equipment, any Raceway utilized by Tenant pursuant to
         the terms hereof, the Leased Premises, the Generator or the Tank, no
         modification or alteration thereof shall be made without Landlord's
         prior written consent, which consent may be withheld in Landlord's

                                       67
<PAGE>
 
         sole discretion or granted on such terms and conditions as Landlord may
         determine in its sole discretion. Tenant shall take all measures
         necessary to insure that the Equipment, the Generator and the Tank do
         not interfere with or disturb the operation of any other equipment or
         business of Landlord or of any other tenant or occupant of the
         Building.

9.       RELEASE OF LIABILITY AND INDEMNITY. Landlord shall not be liable to
         Tenant, or to Tenant's agents, servants, employees, customers or
         invitees for any injury to person or damage to property caused by any
         act, omission, or neglect of Tenant, its agents, servants, employees,
         invitees or any other person entering the Building under the invitation
         of Tenant or arising out of the use of the Raceways, the Generator or
         the Tank by Tenant and the conduct of its business or out of a default
         by Tenant in the performance of its obligations hereunder, other than
         injury or damage which is solely attributable to Landlord's gross
         negligence or willful misconduct. Tenant hereby indemnifies and holds
         Landlord harmless from all liability and claims for any such damage or
         injury. In addition, Tenant shall protect, defend and indemnify
         Landlord, and its mortgagees and Building manager, and each of their
         respective directors, officers, joint venturers, employees and agents,
         and hold them harmless from and against all liability and claims for
         any injury to person or damage to property or business caused by any
         act, omission, or neglect of Tenant, its agents, servants, employees,
         or contractors, or any condition or circumstance relative to the
         license granted hereunder, specifically including, without limitation,
         (i) the installation, maintenance, operation, repair, modification or
         removal of the Equipment, the Generator or the Tank, or (ii) any tort,
         including, without limitation, slander and tortious interference with
         business arising out of the use and operation of the Equipment, or, as
         a result of the content of the transmissions and receptions sent or
         received over or through the Equipment, unless such liability and
         claims arise primarily by reason of the negligence or willful
         misconduct of Landlord, its agents or employees. Landlord and its
         mortgagees, the Building manager and each of their respective
         directors, officers, joint venturers, employees and agents shall also
         not be liable for any consequential or special damages arising out of
         any such injury to person or damage to property or business. This
         release and indemnity is in addition to and not in substitution of any
         other release and indemnity in the Lease.

10.      TRANSFERS BY TENANT. Tenant shall not transfer, convey, mortgage,
         pledge, hypothecate, or encumber Tenant's license interest hereunder or
         grant any license, concession or any other right to use a portion of
         the Raceways without the prior written consent of Landlord, which may
         be granted or withheld in Landlord's sole discretion. Notwithstanding
         the foregoing, Tenant may assign the license granted hereby in
         connection with any assignment of Tenant's entire interest in the Lease
         or a subletting of the entire Leased Premises which is permitted under
         Section 4.7 of the Lease without the necessity of obtaining any further
         approval from Landlord.

11.      COMMENCEMENT OF OPERATIONS. The commencement of operations in the
         Leased Premises by Tenant shall constitute the acknowledgment and
         agreement of Tenant that Tenant is fully familiar with the physical
         condition of the Building (including the mechanical rooms and Raceway
         space of the Building), that Tenant has accepted the same in good order
         and condition, and that the Raceway space complies in all respects

                                       68
<PAGE>
 
         with the requirements hereof and is suitable for the purposes for which
         the same is hereby licensed. In that regard, Landlord hereby disclaims,
         and Tenant hereby waives, any warranty of suitability with respect to
         the Raceway space, and any warranty of fitness for a particular
         purpose.




                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       69
<PAGE>
 
                                  SCHEDULE "1"
                                  ------------

    To Exhibit "H" to Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                              LOCATION OF GENERATOR
                              ---------------------
                        (For illustrative purposes only)

                            [Floorplan appears here]




                                       70
<PAGE>
 
                                   EXHIBIT "I"
                                   -----------

            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                                 RENEWAL OPTION
                                 --------------


1.       DEFINED TERMS. For purposes of this Exhibit "I", all terms defined in
         the Lease (including other exhibits to the Lease) will be utilized
         herein without further definition. In addition, when delineated with
         initial capital letters, the following term shall have the following
         definition and meaning:

         (a) "Renewal Date" shall mean the first day next following the
             expiration date of the Lease Term.


2.       GRANT OF OPTION. Tenant shall have the following option ("Option") to
         renew this Lease:

         Tenant may, by notifying Landlord of its election in writing at least
         six (6) full calendar months prior to the end of the Lease Term, renew
         this Lease for an additional lease term (the "Second Lease Term")
         beginning on the first (1st) Renewal Date and continuing for five (5)
         years thereafter. Such renewal shall be on all of the terms and
         conditions of this Lease which are not inconsistent herewith.

         The Base Rental payable beginning on the first (1st) Renewal Date and
         continuing thereafter shall be at then current market rate.

         If Tenant exercises its option to renew the Lease for a Second Lease
         Term, Tenant may, by notifying Landlord of its election in writing at
         least six (6) full calendar months prior to the end of the Second Lease
         Term, renew this Lease for an additional lease term (the "Third Lease
         Term") beginning on the second (2nd) Renewal Date and continuing for
         five (5) years thereafter. Such renewal shall be on all of the terms
         and conditions of this Lease which are not inconsistent herewith,
         except that no renewal option shall exist during the Third Lease Term.

         The Base Rental payable beginning on the second (2nd) Renewal Date and
         continuing thereafter shall be at then current market rate.


         Failure by Tenant to notify Landlord of Tenant's election to exercise
         the renewal option herein granted within the time limits set forth for
         such exercise shall constitute a waiver of such Option. Notwithstanding
         the foregoing, the Option shall not be applicable at any time when
         there is a default under the Lease which has not been cured after
         applicable

                                       71
<PAGE>
 
         notice and cure periods. In addition, the Option shall automatically
         terminate upon the termination of the Lease Term, whether by Landlord
         upon the occurrence of an event of default or otherwise or, at the
         option of Landlord, in its sole discretion, upon the assignment,
         subletting, or other transfer by Tenant, whether or not with the
         approval of Landlord to any person or entity other than an Affiliate.




                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------


                                       72
<PAGE>
 
                                   EXHIBIT "J"
                                   -----------
            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS, as Tenant

- -------------------------------------------------------------------------------

                             WORK LETTER (ALLOWANCE)
                             -----------------------


This Work Letter ("Work Letter") describes and specifies the right and
obligations of Landlord and Tenant with respect to certain allowances granted to
Tenant hereunder and rights and responsibilities of Landlord and Tenant with
respect to the design, construction and payment for the completion of Tenant's
initial leasehold improvements ("Initial Improvements") within the Leased
Premises.

1.       DEFINITIONS. Terms which are defined in the Lease shall have the same
         meaning in this Work Letter. Additionally, as used in this Work Letter,
         the following terms (when delineated with initial capital letters)
         shall have the respective meaning indicated for each as follows:

         (a)      "Allowance" shall mean an amount not to exceed Two Hundred
                  Seventy-two Thousand Nine Hundred Forty and 00/100ths Dollars
                  ($272,940.00)

         (b)      "Basic Construction of the Building" shall mean the structure
                  of the Building as built on the date of this Work Letter.

         (c)      "Landlord's Architect" shall mean the architect designated by
                  Landlord as its architect, from time to time, to perform the
                  functions of Landlord's Architect hereunder.

         (d)      "Plans and Specifications" shall mean collectively, the plans,
                  specifications and other information prepared or to be
                  prepared by Tenant's Architect and, where necessary, by
                  Landlord's electrical, mechanical and structural engineers,
                  all at Tenant's expense, which shall detail the Work required
                  by Tenant in the Premises and which shall be approved in
                  writing by both Tenant and Landlord prior to the commencement
                  of such Work.

         (e)      "Tenant's Architect" shall mean EPB Design Center LTD, who is
                  an architect licensed to practice in the State of Texas.

         (f)      "Work" shall mean all materials and labor to be added to the
                  Basic Construction of the Building in order to complete the
                  installation of the Initial Improvements within the Leased
                  Premises for Tenant in accordance with the Plans and
                  Specifications, including, without limitation any
                  modifications to the Building,

                                       73
<PAGE>
 
                  any electrical or plumbing work required to meet Tenant's
                  electrical and plumbing requirements, and any special air
                  conditioning work required to be performed in the Leased
                  Premises.

         (g)      "Cost of the Work" shall mean the cost of all materials and
                  labor to be added to the Basic Construction of the Building in
                  order to complete the installation of the Initial Improvements
                  within the Leased Premises in accordance with the Plans and
                  Specifications.

         (h)      "Tenant's Costs" shall mean that portion of the Cost of the
                  Work in excess of Allowance.

         (i)      "Change Costs" shall mean all costs or expenses attributable
                  to any change in the Plans and Specifications which, when
                  added to other costs and expenses incurred in completing the
                  Work, exceed Allowance, including, without limitation, (i) any
                  cost caused by direction of Tenant to omit any item of Work
                  contained in the Plans and Specifications, (ii) any additional
                  architectural or engineering services, (iii) any changes to
                  materials in the process of fabrication, (iv) the cancellation
                  or modification of supply or fabricating contracts, (v) the
                  removal or alteration of any Work or any plans completed or in
                  process, or (vi) delays affecting the schedule of the Work.

         (j)      "Working Days" shall mean all days of the week other than
                  Saturday, Sunday, and legal holidays.

         (k)      "Contractor" shall mean the contractor or contractors engaged
                  by Tenant to perform the Work in accordance with the
                  provisions of Section 4.2(b) of the Lease.

2.       PROCEDURE AND SCHEDULES FOR THE COMPLETION OF PLANS AND SPECIFICATIONS.
         The Plans and Specifications shall be completed in accordance with the
         following procedure and time schedules:

         (a)      Design Drawings. Within sixty (60) Working Days from execution
                  of the Lease, Tenant shall submit to Landlord four (4) sets of
                  prints of design drawings, specifying the intended design,
                  character and finishing of the Initial Improvements within the
                  Leased Premises. Such package shall include separate drawings
                  for signs in accordance with Landlord's sign criteria. The
                  design drawings shall set forth the requirements of Tenant
                  with respect to the installation of the Initial Improvements
                  within the Leased Premises, and such drawings shall include,
                  without limiting their scope, a Tenant approved space plan,
                  architectural design of the space, including office front,
                  plans, elevations, sections, and renderings indicating
                  materials, color selections and finishes.

                  (i)      After receipt of design drawings, Landlord shall
                           return to Tenant one set of Prints of design drawings
                           with Landlord's suggested modifications

                                       74
<PAGE>
 
                           and/or approval within ten (10) Working Days of
                           receipt thereof from Tenant. If, upon receipt of
                           approved design drawings bearing Landlord's comments,
                           Tenant wishes to take exception thereto, Tenant may
                           do so in writing, by certified mail addressed to
                           Landlord, within five (5) Working Days from the date
                           of receipt of Landlord's comments on the design
                           drawings. Unless such action is taken, Tenant will be
                           deemed to have accepted and approved all of
                           Landlord's comments on the design drawings.

                  (ii)     If design drawings are returned to Tenant with
                           comments, but not bearing approval of Landlord, the
                           design drawings shall be immediately revised by
                           Tenant and resubmitted to Landlord for approval
                           within ten (10) Working Days of their receipt by
                           Tenant.

         (b)      Completion of Plans and Specifications. All Plans and
                  Specifications shall be prepared in strict compliance with
                  applicable Building standards and requirements, this Work
                  Letter and otherwise, and shall also adhere to the design
                  drawings approved by Landlord. In order to assure the
                  compatibility of Tenant's electrical and mechanical systems
                  and the compatibility of Tenant's structural requirements with
                  the existing Building and in order to expedite the preparation
                  of Tenant's electrical, mechanical and structural drawings,
                  Tenant or Tenant's Architect shall deliver to Landlord's
                  Architect, not later than thirty (30) Working Days from the
                  date of Landlord's approval of design drawings, a detailed
                  plan setting forth any and all electrical, mechanical and
                  structural requirements, and Landlord's Architect shall
                  retain, at Tenant's expense, Landlord's electrical, mechanical
                  and structural engineers to prepare all necessary electrical,
                  mechanical and structural construction drawings which shall be
                  included as a part of the Plans and Specifications. All
                  construction documents and calculations prepared by Tenant's
                  Architect shall be submitted by Tenant, in the form of four
                  (4) sets of blueline prints, to Landlord for approval within
                  ten (10) Working Days after the date of receipt by Tenant of
                  Landlord's approval of design drawings, electrical, mechanical
                  and structural drawings. If the Plans and Specifications are
                  returned to Tenant with comments, but not bearing approval of
                  Landlord, the Plans and Specifications shall be immediately
                  revised by Tenant and resubmitted to Landlord for approval
                  within fifteen (15) Working Days of their receipt by Tenant.

                  (i)      The fees for Tenant's Architect and any consultants
                           or engineers retained by or on behalf of Tenant or
                           Tenant's Architect (including, but not limited to,
                           the electrical, mechanical and structural engineers
                           required to be retained under this paragraph) shall
                           be paid by Tenant. Tenant shall also pay for any
                           preliminary drawings by Landlord's Architect for
                           review of the design drawings, the Plans and
                           Specifications, and any revisions to such documents,
                           and the fees and expenses of Landlord's Architect for
                           inspection of the Work, as required by Landlord.
                           Tenant may use funds from the Allowance to make such
                           payments.

                                       75
<PAGE>
 
                  (ii)     Tenant shall have the sole  responsibility  for
                           compliance  of the Plans and Specifications with all
                           applicable statutes, codes, ordinances and other
                           regulations, and the approval of the Plans and
                           Specifications or calculations included therein by
                           Landlord shall not constitute an indication,
                           representation or certification by Landlord that such
                           Plans and Specifications or calculations are in
                           compliance with said statutes, codes, ordinances and
                           other regulations. In instances where several sets of
                           requirements must be met, the requirements of
                           Landlord's insurance underwriter or the strictest
                           applicable  requirements shall apply where not
                           prohibited by applicable codes.

3.       TERMINATION RIGHT. If for any reason Landlord and Tenant have not
         agreed in writing upon final Plans and Specifications on or before the
         date which is ninety (90) days from the date of submission to Landlord,
         then Landlord or Tenant shall have the right to terminate the Lease by
         providing the other party with written notice of the electing parties'
         decision to terminate this Lease within thirty (30) days from the
         expiration of such ninety (90) day period. The failure of either party
         to exercise such termination right in the manner and within the time
         period specified above shall be deemed to be an irrevocable waiver of
         such right.

4.       PAYMENT. In the event Landlord acts as the general contractor for the
         Initial Improvements in the Leased Premises, the Allowance will be
         applied to offset the amounts due Landlord as reflected in the monthly
         invoices therefor submitted by Landlord to Tenant. In the event
         Landlord does not act as the general contractor for the Initial
         Improvements in the Leased Premises, Landlord shall pay the Allowance
         to Tenant within thirty (30) days of Landlord's receipt of invoices
         submitted by Tenant to Landlord.

5.       PERFORMANCE OF WORK AND DELAYS. Tenant shall cause the Contractor to
         perform the Work in strict accordance with the Plans and
         Specifications. If a delay shall occur in the completion of the Work by
         Tenant as the probable result of (i) any failure to furnish when due
         Tenant's design drawings, Tenant's electrical, mechanical and/or
         structural requirements, Tenant's Plans and Specifications or any
         revision to any such documents, (ii) any change by Tenant in any of the
         Plans and Specifications, (iii) any state of facts which gives rise to
         a change referred to in the definition of Change Costs or any changes
         resulting in a Change Cost, (iv) any other act or omission of Tenant,
         its agents or employees, including any violation of the provisions of
         the Lease or any delay in giving authorizations or approvals pursuant
         to this Work Letter, or (v) any other cause except (a) as specified in
         Section 8.1 of the Lease or (b) arising from a default by Landlord,
         then any such delay shall not justify any extension of the Commencement
         Date of the Lease.

6.       CHANGE ORDERS. All changes and modifications in the Work from that
         contemplated in the Plans and Specifications, whether or not such
         change or modification gives rise to a Change Cost, must be evidenced
         by a written Change Order executed by both Landlord and Tenant. In that
         regard, Tenant shall submit to Landlord such

                                       76
<PAGE>
 
         information as Landlord shall require with respect to any Change Order
         requested by Tenant. After receipt of requested Change Order, together
         with such information as Landlord shall require with respect thereto,
         Landlord shall return to Tenant either the executed Change Order, which
         will evidence Landlord's approval thereof, or the Plans and
         Specifications with respect thereto with Landlord's suggested
         modification.

7.       WHOLE AGREEMENT; NO ORAL MODIFICATION. This Work Letter embodies all
         representations, warranties and agreements of Landlord and Tenant with
         respect to the matter described herein, and this Work Letter may not be
         altered or modified except by an agreement in writing signed by the
         parties.

8.       PARAGRAPH HEADINGS. The paragraph headings contained in this Work
         Letter are for convenient reference only and shall not in any way
         affect the meaning or interpretation of such paragraphs.

9.       NOTICES. All notices required or contemplated hereunder shall be given
         to the parties in the manner specified for giving notices under the
         Lease.

10.      BINDING EFFECT. This Work Letter shall be construed under the laws of
         the State of Texas and shall be binding upon and shall inure to the
         benefit of the parties hereto and their respective permitted successors
         and assigns.

11.      CONFLICT. In the event of conflict between this Work Letter and any
         other exhibits or addenda to this Lease, this Work Letter shall
         prevail.







                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------


                                       77
<PAGE>
 
                       THIS PAGE INTENTIONALLY LEFT BLANK


                                       78
<PAGE>
 
                                   EXHIBIT "K"
                                   -----------
            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS as Tenant

- -------------------------------------------------------------------------------

                           ROOFTOP COOLING PROVISIONS
                           --------------------------

This Exhibit "K" describes and specifies the right to install dry cooling
equipment upon the roof of the Building hereby granted by Landlord to Tenant,
which is being granted upon the following terms and conditions:

1.        DEFINED TERMS. Terms defined in the Lease and delineated herein by
          initial capital letters shall have the same meaning ascribed thereto
          in the Lease, except to the extent that the meaning of such term is
          specifically modified by the provisions hereof. In addition, other
          terms not defined in the Lease but defined herein will, when
          delineated with initial capital letters, have the meanings ascribed
          thereto in this Exhibit. Terms and phrases which are not delineated by
          initial capital letters shall have the meanings commonly ascribed
          thereto.

2.        GRANT OF LICENSE. Subject to the terms and provisions of this Exhibit,
          Landlord hereby grants to Tenant the right and license to install,
          operate, maintain, repair and replace a maximum of [NUMBER (##)] dry
          cooling units (the dimension of each of which shall not exceed a
          maximum surface area of 1,500 square feet), together with related
          wiring, piping, vents and equipment, including [# OF PIPES] [#INCHES]"
          pipes to and from the Leased Premises and such equipment
          (collectively, the "Cooling Equipment") on the roof of the Building.
          The size, location, and manner of installation of the Cooling
          Equipment shall be approved by Landlord as part of the approval of the
          Plans and Specifications pursuant to Exhibit "J" hereto,  which
          approval shall take into  consideration the functional requirements of
          the Cooling Equipment and of any other equipment located on the roof
          of the Building and shall be subject to standards of structural and
          architectural integrity with respect to the Building (and, in that
          regard, the Cooling Equipment shall be located so as not to be visible
          except from above the Building, shall complement the Building color,
          and shall have no visible marking or logo). It is understood and
          acknowledged that the area to be covered by the Cooling Equipment,
          including necessary walkways and required airspace, shall not exceed
          [###] square feet. The license granted to Tenant shall commence on the
          Commencement Date and shall expire upon the expiration or earlier
          termination of the Lease Term.

3.        LICENSE FEE. Four Thousand Two Hundred eighteen and 75/100th Dollars
          ($4,218.75) per month, commencing on the Rental Commencement Date.
          Additional dry cooling units may be added with the approval of
          Landlord (the size and location of which will be at Landlord's
          reasonable option) and the License Fee for each such additional
          cooling equipment will be at the then current Landlord charge for such
          additional cooling equipment.

                                       79
<PAGE>
 
4.        INSTALLATION, MAINTENANCE, AND REPAIR. Tenant shall, at Tenant's sole
          cost and expense, provide for the installation of the Cooling
          Equipment and for all service, repairs, and maintenance to the Cooling
          Equipment. With respect to the installation of the Cooling Equipment,
          the Cooling Equipment shall not be affixed to the roof of the Building
          by nail, bolt, screw, or other device which penetrates the roof
          (except as approved in writing by Landlord), and all wiring
          penetrations , venting penetrations and piping penetrations shall be
          made by Landlord's roofing contractor at Tenant's sole cost and
          expense, which shall be limited to the actual and reasonable cost
          thereof. The Cooling Equipment shall be maintained by Tenant in good
          order and repair and in a safe condition. In the event that Tenant
          fails to so maintain the Cooling Equipment and Landlord, in Landlord's
          sole discretion, deems such failure to present a danger of injury to
          persons or damage to property in or about the Building, Landlord may
          affect such repairs or maintenance and recover the cost thereof from
          Tenant, which sum shall be due and payable within ten (10) days after
          Landlord's written notice to Tenant with respect thereto. Tenant shall
          provide Landlord with prior written notice of Tenant's need to effect
          service, maintenance, or repairs hereunder and shall thereupon have
          access to the roof of the Building and other non-tenant areas of the
          Building at such times and under such conditions as may be prescribed
          by Landlord. Landlord may charge Tenant for any equipment and material
          of Landlord used by Tenant with respect thereto, at Landlord's
          standard rates. The Cooling Equipment shall be a Trade Fixture as
          defined in Section 1.18 of the Lease.

5.       INTERFERENCE. Landlord assumes no responsibility for any interference
         in the use or installation of the Cooling Equipment. Tenant shall, at
         Tenant's option, either modify the Cooling Equipment or relocate the
         Cooling Equipment to another area approved by Landlord in the event
         that the Cooling Equipment, in Landlord's reasonable judgment causes
         any interference with or disturbs the operation of any other equipment
         or business of Landlord or any other occupant of the Building or
         creates or results in any noise, odor, or nuisance to any other
         occupant of the Building, or the areas adjacent thereto. However, if
         the need to modify or relocate the Cooling Equipment is caused by the
         exercise of any right granted by Landlord to other occupants of the
         Building after the Commencement Date or changes to any other equipment
         of Landlord of any other occupant of the Building after the
         Commencement Date, then Landlord shall bear the cost of modifying or
         relocating the Cooling Equipment. In the event that Landlord determines
         that the Cooling Equipment causes any interference with or disturbs the
         operation of any other Cooling Equipment or business of Landlord or any
         other occupant of the Building, and Tenant fails to modify or is unable
         to modify the Cooling Equipment so as to eliminate such interference,
         Landlord shall, prior to making a decision that the Cooling Equipment
         needs to be shut off, take into account the nature of the interference
         and the reasonable business needs of both Tenant and the other occupant
         of the Building (including Landlord) being affected and shall consult
         with Tenant regarding this matter. Tenant must shut off the Cooling
         Equipment within a reasonable period of time after notification of the
         interference or disturbance from Landlord, taking into account the
         nature of the interference and Tenant's reasonable business needs; and
         Tenant may restore, modify, or relocate the Cooling Equipment to test
         for interference only with

                                       80
<PAGE>
 
         Landlord's permissions, which shall not be unreasonably withheld,
         delayed or conditioned.

6.        USE. The Cooling Equipment is solely for use for Tenant's internal
          business and the benefits of the Cooling Equipment may not be provided
          by Tenant to third parties except Tenant's Customers. The Cooling
          Equipment may not be sold or rented by Tenant to third parties, nor
          may Tenant sublet or assign the license granted to Tenant hereunder,
          except in connection with any assignment or sublease which is
          permitted under Section 4.7 of the Lease. Tenant shall operate the
          Cooling Equipment in compliance with all applicable laws, regulations,
          and rules of the governmental authorities having jurisdiction thereof
          and shall maintain all necessary licenses and permits with respect
          thereto. Any electrical usage associated with the Cooling Equipment
          shall be governed by the provisions of Section 2.5 of the Lease.

7.        INTERRUPTION. Landlord may, at Landlord's sole discretion but without
          cost to Landlord, upon such advance notice to Tenant as is reasonable
          under the circumstances, taking into account the nature of the
          repairs, maintenance or modification needing to be made by Landlord
          and (after consultation with Tenant) Tenant's reasonable business
          needs, require interruption of service or relocation or removal of the
          Cooling Equipment for repairs, maintenance, or modification of the
          Building, including, but not limited to, roofing, structural,
          electrical, or mechanical repairs.

8.        MODIFICATION AND SUBSTITUTION. Tenant may not substitute or modify the
          Cooling Equipment or any part thereof, without the prior written
          approval of Landlord, which consent shall not be unreasonably withheld
          or delayed. It is understood and agreed that it shall not be
          unreasonable if Landlord disapproves any such substitution or
          modification because of a material increase in the size or area
          covered by the Cooling Equipment. Any substitution or modification
          approved by Landlord shall automatically become a part of the Cooling
          Equipment, and all terms of this Exhibit shall apply to such
          substitution and/or modification.

9.        RESTORATION. Tenant shall, at Tenant's sole cost and expense, remove
          the Cooling Equipment and repair any damage to the Building caused by
          such removal if the Lease Term, and the license herein granted,
          terminates,  whether by expiration of the Lease Term or otherwise.
          Such removal and restoration work shall be completed by Tenant within
          sixty (60) days of the date on which the condition requiring such
          removal and restoration work occurs. In the event that Tenant shall
          fail to complete the removal of the Cooling Equipment and the
          restoration of the Building within such sixty (60) day period,
          Landlord shall have the right to effect such removal and restoration,
          but shall not be obligated to do so, in which event, Tenant shall
          reimburse Landlord for all costs incurred by Landlord in performing
          such removal and restoration work. In addition, any Cooling Equipment
          remaining at the Building subsequent to the expiration of such sixty
          (60) day period and upon prior written notice to Tenant shall be
          deemed to have been abandoned by Tenant, so that in no event shall
          Landlord have any duty to preserve or restore the Cooling Equipment on
          Tenant's behalf. If Landlord does choose to store the Cooling
          Equipment on Tenant's behalf, the cost of storage incurred by Landlord
          shall be

                                       81
<PAGE>
 
          reimbursed by Tenant on demand. In such event, Landlord shall also
          have the right to sell such Cooling Equipment for salvage value and to
          apply the proceeds derived from such sale to sums owing by Tenant to
          Landlord hereunder. The provisions of this Paragraph 9 shall survive
          the expiration of the license granted hereunder and of the lease Term.

10.       REPRESENTATIONS OF TENANT. As a material inducement to Landlord to
          enter into this Exhibit and to grant the license to Tenant described
          in Paragraph 2 hereof, Tenant hereby represents and warrants to
          Landlord that (a) the Cooling Equipment has received all necessary
          approvals; (b) the Cooling Equipment will be installed in accordance
          with the plans and specifications therefore as approved by Landlord in
          accordance with the provisions of Exhibit "J"; (c) the Cooling
          Equipment is designed to require minimum maintenance; (d) the Cooling
          Equipment will not emit any fluids or gases which constitute hazardous
          materials or substances under applicable environmental laws or
          regulations, or which could otherwise cause damage to persons or
          property; (e) the Cooling Equipment will not interfere with other
          equipment presently located on the rooftop of the Building or in the
          Building; and (f) Tenant will have received all necessary licenses and
          permits from all applicable governmental  authorities regarding the
          installation and operation of the Cooling Equipment, prior to such
          installation and operation, and (g) the Cooling Equipment will
          strictly comply with all laws, rules, ordinances and codes whether now
          or existing of all Federal, State, and all local government
          authorities.

11.       INDEMNIFICATION. In addition to the indemnification and obligations of
          Tenant under the Lease, Tenant shall protect, defend, indemnify, and
          hold Landlord harmless from (i) all liability and claims for any
          injury to person or damage to property caused by any act, omission, or
          neglect of Tenant, its agents, servants, employees, or contractors,
          relative to the license, including, without limitation, the
          installation, operation, repair, and maintenance of the Cooling
          Equipment, unless such liability and claims arise primarily by reason
          of the negligence or willful misconduct of Landlord, its agents,
          contractors or employees, and (ii) all losses, damages or liabilities
          that may be suffered or incurred by Landlord in connection with
          Landlord's inability to complete any necessary repairs, maintenance,
          or modification of the Building, including, but not limited to,
          roofing, structural, electrical or mechanical repairs, as a result of
          Tenant's failure to allow interruption of service or relocation or
          removal of the Cooling Equipment pursuant to Section 7 of this
          Exhibit.

12.       CASUALTY DAMAGE. Landlord shall not be liable to Tenant for any loss
          or damage to all or any part of the Cooling Equipment occasioned by
          theft, fire, act of God, public enemy, injunction, riot, vandalism,
          malicious mischief, earthquake, flood, strike, insurrection, war,
          court order, requisition, or order of governmental body or authority
          or by any other cause whatsoever, other than that solely caused by the
          gross negligence or willful misconduct of Landlord, its agents,
          contractors or employees. Nor shall Landlord be liable for any damage
          or inconvenience which may arise through the repair or alteration of
          any part of the Building or through termination of the license granted
          pursuant to this Exhibit "L" following a default under Section 15
          hereof, other than

                                       82
<PAGE>
 
                                   EXHIBIT "L"
                                   -----------

            To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS as Tenant

- -------------------------------------------------------------------------------

             SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT
             -------------------------------------------------------


NOTICE: THIS SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT RESULTS IN
YOUR LEASEHOLD ESTATE IN THE PROPERTY BECOMING SUBJECT TO AND OF LOWER PRIORITY
THAN THE LIEN OF SOME OTHER OR LATER SECURITY INSTRUMENT.

THIS AGREEMENT is entered into by and among Tenant, Landlord, and Beneficiary
and effects the Property described in Schedule "A" attached hereto. The terms
"Tenant", "Landlord", "Beneficiary", "Premises", "Lease", "Property", "Loan",
"Note", and "Mortgage" are defined in the schedule of Definitions attached
hereto as Schedule "B". This Agreement is entered into with reference to the
following facts:

(a)      Landlord and Tenant have entered into the Lease covering the Premises
         in the Property.

(b)      Beneficiary has agreed to make the Loan to Landlord to be evidenced by
         the Note, which Note is to be secured by the Mortgage covering the
         Property, provided that the Lease is subordinate to the lien of the
         Mortgage.

(c)      For the purposes of completing the Loan, the parties hereto desire
         expressly to acknowledge the subordination of the Lease to the lien of
         the Mortgage, it being a condition precedent to Beneficiary's
         obligation to consummate the Loan that the lien of the Mortgage be
         unconditionally and at all times prior and superior to the leasehold
         interests and estates created by the Lease.

(d)      Tenant has requested that Beneficiary agree not to disturb Tenant's
         possessory rights in the Premises in the event Beneficiary should
         foreclose the Mortgage; provided that Tenant is not then in default
         under the Lease and provided further that Tenant attorns to Beneficiary
         or the purchaser at any foreclosure or trustee's sale of the Property.

NOW, THEREFORE, in consideration of the mutual covenants contained herein and of
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties agree as follows:

1.       SUBORDINATION. Notwithstanding anything to the contrary set forth in
         the Lease, Tenant hereby acknowledges that the Lease and the leasehold
         estate created thereby and all of Tenant's rights thereunder shall be
         and shall at all times remain subject, subordinate and inferior to the
         Mortgage and the lien thereof, and all rights of Beneficiary thereunder
         and to any and all renewals, modifications, consolidations,
         replacements and extensions thereof.

                                       83
<PAGE>
 
2. ACKNOWLEDGEMENT AND AGREEMENT BY TENANT. Tenant acknowledges that:

                  (a) Beneficiary would not make the Loan without this
                  Agreement;

                  (b) It acknowledges the Mortgage and the agreements evidencing
                  and securing the Loan; and

                  (c) Beneficiary, in making any disbursements to Landlord, is
                  under no obligation or duty to oversee or direct the
                  application of the proceeds of such disbursements, and such
                  proceeds may be used by Landlord for purposes other than
                  improvement of the Property.

                  (d) From and after the date hereof, in the event of any act or
                  omission by Landlord which would give Tenant the right, either
                  immediately or after the lapse of time, to terminate the Lease
                  or to claim a partial or total eviction, Tenant will not
                  exercise any such right:

                           (i) until it has given written notice of such act or
                           omission to Beneficiary, which notice shall be given
                           not later than the number of days required by the
                           Lease for such notice to the Landlord; and

                           (ii) until the same period of time as is given to
                           Landlord under the Lease to cure such act or omission
                           shall have elapsed following such giving of notice to
                           Beneficiary and following the time when Beneficiary
                           shall have become entitled under the Mortgage to
                           remedy the same.

                  (e) It has notice that the Lease and the rent and all other
                  sums due thereunder have been assigned or are to be assigned
                  to Beneficiary as security for the Loan secured by the
                  Mortgage. In the event that Beneficiary notifies Tenant of a
                  default under the Mortgage and demands that Tenant pay its
                  rent and all other sums due under the Lease to Beneficiary,
                  Tenant shall honor such demand and pay its rent and all other
                  sums due under the Lease directly to Beneficiary or as
                  otherwise required pursuant to such notice.

                  (f) It shall send a copy of any notice or statement under the
                  Lease to Beneficiary at the same time such notice or statement
                  is sent to Landlord.

                  (g) It has no right or option of any nature whatsoever,
                  whether pursuant to the Lease or otherwise, to purchase the
                  Premises or the Property, or any portion thereof or any
                  interest therein, and to the extent that Tenant has had, or
                  hereafter acquires, any such right or option, the same is
                  hereby acknowledged to be subject and subordinate to the
                  Mortgage and is hereby waived and released as against
                  Beneficiary.

                                       84
<PAGE>
 
                  (h) This Agreement satisfies any condition or requirement in
                  the Lease relating to the granting of a non-disturbance
                  agreement.

3.       FORECLOSURE AND SALE. In the event of foreclosure of the Mortgage, or
         upon a sale of the Property pursuant to the trustee's power of sale
         contained therein, or upon a transfer of the Property by conveyance in
         lieu of foreclosure, then:

                  (a) Non-Disturbance. So long as Tenant complies with this
                  Agreement and is not in default under any of the terms,
                  covenants, or conditions of the Lease after applicable notice
                  and cure periods (if any), the Lease shall continue in full
                  force and effect as a direct lease between the succeeding
                  owner of the Property and Tenant, upon and subject to all of
                  the terms, covenants and conditions of the Lease, for the
                  balance of the term of the Lease including renewal terms.
                  Tenant hereby agrees to adhere to and accept any such
                  successor owner as landlord under the Lease, and to be bound
                  by and perform all of the obligations imposed by the Lease and
                  Beneficiary, or any such successor owner of the Property, will
                  not disturb the possession of Tenant, and will be bound by all
                  of the obligations imposed on the Landlord by the Lease,
                  provided, however, that Beneficiary, or any purchaser at a
                  trustee's or sheriff's sale or any successor owner of the
                  Property shall not be:

                           (i) liable for any act or omission of a prior
                           landlord (including Landlord); or

                           (ii) subject to any offsets or defenses which Tenant
                           might have against any prior landlord (including
                           Landlord); or

                           (iii) bound by any rent or additional rent which
                           Tenant might have paid in advance to any prior
                           landlord (including Landlord) for a period in excess
                           of one (1) month, except for scheduled payments of
                           additional rent, or by any security deposit, cleaning
                           deposit, or other prepaid charge which Tenant might
                           have paid in advance to any prior landlord (including
                           Landlord); or

                           (iv) bound by any agreement or modification of the
                           Lease made without the written consent of
                           Beneficiary.

                  (b) New Lease. Upon the written request of either Beneficiary
                  or Tenant to the other given at the time of any foreclosure,
                  trustee's sale or conveyance in lieu thereof, the parties
                  agree to execute a lease of the Premises upon the same terms
                  and conditions as the Lease between Landlord and Tenant, which
                  lease shall cover any unexpired term of the Lease existing
                  prior to such foreclosure, trustee's sale or conveyance in
                  lieu of foreclosure.

                  (c) Beneficiary shall have no responsibility to provide (or
                  liability for not providing) any additional space for which
                  Tenant has any option or right under

                                       85
<PAGE>
 
                  the Lease if, as a result of any lease or leases entered into
                  with other tenants prior to Beneficiary acquiring title to the
                  Property, a conflict exists between such other lease or leases
                  and the right or option of Tenant with respect to additional
                  space, unless Beneficiary at its option elects to provide the
                  same and Tenant hereby releases Beneficiary from any
                  obligation it may otherwise have to provide the same, and
                  agrees that Tenant shall have no right to cancel the Lease,
                  abate rent or assert any claim against Beneficiary as a result
                  of the failure to provide any option space.

                  (d) Beneficiary shall have no liability to Tenant or any other
                  party for any conflict between the provisions of the Lease and
                  the provisions of any other lease affecting the Property,
                  including, but not limited to, any provisions relating to
                  renewal options and options to expand, and in the event of
                  such a conflict, Tenant shall have no right to cancel the
                  Lease or take any other remedial action against Beneficiary or
                  action against any other party for which Beneficiary would be
                  liable.

4.       ACKNOWLEDGEMENT AND AGREEMENT BY LANDLORD. Landlord, as landlord under
         the Lease and mortgagor or trustor under the Mortgage, acknowledges and
         agrees for itself and its heirs, successors and assigns, that:

                  (a) This Agreement does not:

                           (i) constitute a waiver by Beneficiary of any of its
                           rights under the Mortgage; and/or

                           (ii) in any way release Landlord from its obligations
                           to comply with the terms, provisions, conditions,
                           covenants, agreements and clauses of the Mortgage;

                  (b) The provisions of the Mortgage remain in full force and
                  effect and must be complied with by Landlord; and

                  (c) In the event of a default under the Mortgage, Tenant may
                  pay all rent and all other sums due under the Lease to
                  Beneficiary as provided in this Agreement.

5.       NO OBLIGATION OF BENEFICIARY. Beneficiary shall have no obligation or
         incur any liability with respect to the erection or completion of the
         improvements in which the Premises are located or for completion of the
         Premises or any improvements for Tenant's use and occupancy, either at
         the commencement of the term of the Lease or upon any renewal or
         extension thereof or upon the addition of additional space, pursuant to
         any expansion rights contained in the Lease.

6.       NOTICE. All notices, consents, waivers or other communications which
         this Lease requires or permits any party to give to another shall be in
         writing and shall be given only by registered, certified or "Express"
         mail, or by Federal Express or other similar courier

                                       86
<PAGE>
 
         service, return receipt requested, postage prepaid, to the recipient
         party at the addresses set forth in Schedule "B" to this Agreement. Any
         party may change its notice address at any time by giving written
         notice of such change to the other party in the manner provided herein
         at least ten (10) days prior to the date such change is effected. All
         notices under this Lease shall be deemed given, received, made or
         communicated on the delivery date or attempted delivery date shown on
         the return receipt or similar document utilized by the courier service
         for the purpose of indicating delivery.

7.       MISCELLANEOUS.

         (a)      This Agreement supersedes any inconsistent provision of the
                  Lease.

         (b)      Nothing contained in this Agreement shall be construed to
                  derogate from or in any way impair or affect the lien and
                  charge or provisions of the Mortgage.

         (c)      Beneficiary shall have no obligations nor incur any liability
                  with respect to any warranties of any nature whatsoever,
                  whether pursuant to the Lease or otherwise, including, without
                  limitation, any warranties respecting use, compliance with
                  zoning, Landlord's title, Landlord's authority, habitability,
                  fitness for purpose or possession.

         (d)      In the event that Beneficiary shall acquire title to the
                  Premises or the Property, Beneficiary shall have no
                  obligation, nor incur liability, beyond Beneficiary's then
                  equity interest, if any, in the Premises, and Tenant shall
                  look exclusively to such equity interest of Beneficiary, if
                  any, in the Premises for the payment and discharge of any
                  obligations imposed upon Beneficiary hereunder or under the
                  Lease, and Beneficiary is hereby released and relieved of any
                  other obligations hereunder and under the Lease.

         (e)      This Agreement shall inure to the benefit of the parties
                  hereto, their respective successors and permitted assigns;
                  provided, however, that in the event of the assignment or
                  transfer of the interest of Beneficiary, all obligations and
                  liabilities of Beneficiary under this Agreement shall
                  terminate, and thereupon all such obligations and liabilities
                  shall be the responsibility of the party to whom Beneficiary's
                  interest is assigned or transferred; and provided further that
                  the interest of Tenant under this Agreement may not be
                  assigned or transferred without the prior written consent of
                  Beneficiary.

         (f)      This Agreement shall be governed by and construed in
                  accordance with the laws of the state in which the Property is
                  located.

                                       87
<PAGE>
 
IN WITNESS WHEREOF, the parties have executed this Subordination,
Non-Disturbance, and Attornment Agreement as of the ________ day of
____________________, 19____.

IT IS RECOMMENDED THAT, PRIOR TO THE EXECUTION OF THIS SUBORDINATION,
NON-DISTURBANCE AND ATTORNMENT AGREEMENT, THE PARTIES CONSULT WITH THEIR
ATTORNEYS WITH RESPECT THERETO.

                             B E N E F I C A R Y
                             -------------------

                             ____________________, a _______________________

                             By:
                                -----------------------------------
                             Name:
                                  ---------------------------------
                             Title:
                                   --------------------------------


                             L A N D L O R D
                             ---------------

                             INFOMART-Dallas, L.P., a Texas limited partnership

                             By: INFOMART USA, L.P., a Texas limited partnership

                                   By: /s/ ????????????????????
                                      -----------------------------------
                                   Name:
                                        ---------------------------------
                                   Title: Authorized Agent
                                         --------------------------------

                             T E N A N T
                             -----------

                             FOCAL COMMUNICATIONS CORPORATION OF
                             TEXAS, a Delaware corporation

                             By: /s/ Brian F. Addy
                                -----------------------------------
                             Name:   Brian F. Addy
                                  ---------------------------------
                             Title:  Executive Vice President
                                   --------------------------------

Schedule "A" - Property Description
Schedule "B" - Schedule of Definitions

                                    INITIALS

                    Landlord                 Tenant
                            -----------            -----------

                                       83
<PAGE>
 
                                  SCHEDULE "A"
                                  ------------
    To Exhibit "L" To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS as Tenant

- -------------------------------------------------------------------------------

                                LEGAL DESCRIPTION
                                -----------------

BEING a 25.454 acre tract of land situated in the City of Dallas, Dallas County,
Texas and out of the James A. Sylvester Survey, Abstract No. 1383 and being a
part of City of Dallas Block No. 6053, also being the same tract of land
conveyed to Dallas Market Center Company by a Special Warranty Deed recorded in
Volume 82113, Page 3240 of the Deed Records of Dallas County, Texas, said 25.454
acre tract of land being more particularly described as follows:

BEGINNING at a 1/2 inch iron rod found for the point of intersection of the
southwesterly right-of-way line of the Chicago Rock Island and Pacific Railroad
with the northwesterly right-of-way line of Oak Lawn Avenue;

THENCE with the northwesterly right-of-way line of Oak Lawn Avenue the
following:

         South 3131'40" West a distance of 366.74 feet to an "X" chiseled in
         concrete found for corner in a curve to the right, the radius point of
         said curve bearing North 5008'58" West a distance of 241.00 feet from
         said "X";

         Southwesterly with said curve to the right through a central angle of
         0309'20" an arc distance of 13.27 feet to an "X" chiseled in concrete
         set for the point of reverse curvature of a curve to the left having a
         radius of 259.00 feet;

         Southwesterly with said curve to the left through a central angle of
         1128'43" an arc distance of 51.89 feet to a 1/2 inch iron rod found for
         the point of reverse curvature of a curve to the right having radius of
         129.00 feet;

         Southwesterly with said curve to the right through a central angle of
         2406'22" an arc distance of 138.22 feet to a 1/2 inch iron rod set for
         the point of compound curvature of a curve to the right having a radius
         of 50.00 feet;

         Northwesterly with said curve to the right through a central angle of
         2406'22" an arc distance of 21.04 feet to a 1/2 inch iron rod found in
         the northeasterly right-of-way line of Stemmons Freeway for the point
         of compound curvature of a curve to the right having a radius of
         1130.92 feet;

THENCE with the northeasterly right-of-way line of Stemmons Freeway the
following:

         Northwesterly with said curve to the right through a central angle of
         0724'40" an arc distance of 146.28 feet to a 1/2 inch iron rod found
         for the point of tangency of said curve;

                                       89
<PAGE>
 
         North 5533'45" West a distance of 816.18 feet to a 1/2 inch iron rod
         found for point of curvature of a curve to the left having a radius of
         3289.04 feet;

         Northwesterly with said curve to the left through a central angle of
         0123'21" an arc distance of 79.74 feet to a bolt in concrete found for
         the most southerly corner of a tract of land leased to Southwestern
         Furniture Mart Co. from Industrial Properties Corporation as recorded
         in Volume 67076, Page 0690 of the Deed Records of Dallas County, Texas;

THENCE departing the northerly right-of-way line of Stemmons Freeway with the
easterly line of the Southwestern Furniture Mart Company tract, North 0921'30"
East a distance of 1064.46 feet to a 1/2 inch iron rod found for corner in the
curving southwesterly right-of-way line of the Chicago, Rock Island and Pacific
Railroad, the radius point of said curve being situated South 3311'48" West a
distance of 1599.88 feet;

THENCE with the southerly right-of-way lien of the Chicago, Rock Island and
Pacific Railroad the following:

         Southeasterly with said curve to the right through a central angle of
         0241'48" an arc distance of 75.30 feet to a 1/2 inch iron rod found for
         corner;

         North 5207'00" East a distance of 30.11 feet to a 1/2 inch iron rod
         found for corner in a curve to the right, the radius point of said
         curve being situated South 3219'18" West a distance of 1553.95 feet;

         Northwesterly with said curve to the right through a central angle of
         2126'39" an arc distance of 581.59 feet to a 1/2 inch iron rod set for
         corner;

         North 4516'10" East a distance of 53.07 feet to 1/2 inch iron rod set
         for corner; South 3148'40" East a distance of 976.20 feet to the POINT
         OF BEGINNING;

CONTAINING an area of 25.454 acres of land.


                                       90
<PAGE>
 
                                  SCHEDULE "B"
                                  ------------

    To Exhibit "L" To Lease Agreement By and Between INFOMART-Dallas, L.P.,
      as Landlord and FOCAL COMMUNICATIONS CORPORATION OF TEXAS as Tenant

- --------------------------------------------------------------------------------

                             SCHEDULE OF DEFINITIONS
                             -----------------------


Beneficiary shall mean ___________________________________, a
___________________________________ . All notices to Beneficiary shall be mailed
to:

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

with copy to:

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

and a copy to:

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

         ----------------------------------------

Mortgage shall mean a first lien Mortgage or Deed of Trust and Security
Agreement with Assignment of Rents dated as , encumbering the Property, executed
by Landlord, as Mortgagor or Trustor, to , as Trustee, in favor of Beneficiary,
securing repayment of the Loan evidenced by the Note, to be recorded in the
records of the county in which the Property is located.

91
<PAGE>
 
Landlord shall mean _______________________,  a _____________, having an office
at ___________________.

Lease shall mean a certain lease entered into by and among Landlord and Tenant
dated as of ________________, 19__, covering the premises.

Loan shall mean a first mortgage loan in an amount up to _____________________
from Beneficiary to Landlord.

Note shall mean that certain ____________________ Note executed by Landlord in
favor of _______________, a _________________, dated as of _______________,
19__, in the amount of _____________________.

Premises shall mean certain space in the Improvements located in and upon the
Property.

Property shall mean the real property described in Schedule "A" attached hereto
together with the improvements thereon.

Tenant shall mean ___________________, a ________________ corporation, having an
office located at ________________.

                                       92
<PAGE>
 
         [LETTERHEAD OF DATA CENTER DESIGN and DEVELOPMENT CORPORATION]




February 5, 1999

Chris Rehor
FOCAL COMMUNICATIONS CORPORATION
200 N. La Salle Street
Chicago, IL  60601

                                                        VIA: U.S.P.S. PRIORITY

                        Re:  1950 Stemmons Freeway, Dallas, TX
                             FOCAL-DALLAS   DCDDC#98-149

                   Subject:  Change Order #1


Dear Mr. Rehor:

Enclosed are three (3) original copies of Change Order #1 dated February 5, 1999
for credits due to Focal Communications Corporation because of the deletion of
one (1) UPS and related equipment markup, one (1) fire-rated glass window and
related installation, and DCDDC's overhead & profit. Total value of the 
aforementioned is: $(126,722.30) CREDIT.

These original documents have been singed and dated by the Architect and Data
Center Design and Development Corporation. If acceptable, please execute and
date all three copies, and return the fully executed Architect and Contractor
copies to my attention for distribution.

Please contact me immediately if you have any questions. Thank you for your
assistance.

Sincerely,
Data Center Design and Development Corporation

/s/ Louis D. Blatnick

Louis D. Blatnick, CSI
Manager, Project and Business Administration



LDB/ldb

C:  Administrative
     Jeff Wells, VP - Focal

98-149 TRANS-CHRIS REHOR-REV'D CO#1
<PAGE>
 
                           STANDARD FORM OF AGREEMENT
                       BETWEEN OWNER AND DESIGNER-BUILDER
                      FOR DESIGN AND CONSTRUCTION SERVICES

THIS AGREEMENT made as of 12 January 1999 by and between Focal Communications
(thereinafter called "Owner"), and Data Center Design and Development
Corporation, 630 North Court, Palatine, Illinois 60067 (hereinafter called
"Designer-Builder").

WITNESSETH:

That in consideration of the mutual covenants and agreements herein contained,
the parties hereto do hereby covenant and agree as follows:

ARTICLE 1:  DEFINITIONS

1.1      OWNER: "Owner" shall mean the above-named organization designated as
         "Owner", its successors and assigns.

1.2      OWNER'S REPRESENTATIVE: "Owner's Representative" shall mean such person
         designated by the Owner on written notice to Designer-Builder, to act
         as its representative.

1.3      DESIGNER-BUILDER: "Designer-Builder" shall mean the above-named
         organization designated as "Designer-Builder", its successors and
         assigns.

1.4      DESIGNER-BUILDER'S REPRESENTATIVE: "Designer-Builder's Representative"
         shall mean or such other person as may be designated by
         Designer-Builder on written notice to Owner to act as its
         representative.

1.5      WORK: "Work" shall cover all labor, material and services necessary to
         produce the design services and the construction required by the
         contract documents.

1.6      DATE OF SUBSTANTIAL COMPLETION: "Date of "Substantial Completion" of
         the work or a designated portion thereof is the date when: (i) the
         construction is sufficiently completed in accordance with the contract
         documents so that Owner may occupy the work or designated portion
         thereof for the use for which it is intended, or (ii) Owner obtains a
         temporary certificate or a permanent certificate of occupancy for the
         work, and Designer-Builder has obtained a waiver of all liens,
         mechanics and otherwise and has presented same to Owner.

1.7      CONSTRUCTION CHANGE DIRECTIVE: A "Construction Change Directive" is a
         written order to the Designer- Builder, prepared by the
         Designer-Builder signed by the Owner's Representative, issued after the
         execution of this contract, authorizing the Designer-Builder to make
         additions, deletions or modifications in the work to be performed by
         Designer-Builder.

1.8      CHANGE ORDER: A "Change Order" is a written order to the
         Designer-Builder, prepared by Designer-Builder, signed by the Owner's
         Representative, countersigned by Designer-Builder's Representative,
         issued after the execution of the contract, authorizing an adjustment
         (if any) in the contract sum to be paid to Designer-Builder or an
         adjustment in the time for the completion of the work.

ARTICLE 2:  CONTRACT DOCUMENTS

2.1      The contract documents shall consist of the following:

2.1.1    This contract, together with Appendices attached hereto, and any
         amendments or modifications thereto, including any signed work order or
         signed exchange order.

2.1.2    All other documents described in Appendices attached hereto and made
         part hereof.
<PAGE>
 
2.2      In the event of conflict between this contract and the provisions of
         the other contract documents, this contract shall control.  In the
         event of any conflict between the provisions of the contract documents,
         other than this contract, the latest approved document shall control.

2.3      All contract documents hereinafter submitted by Designer-Builder for
         the approval of Owner in connection with the performance of the work
         shall be deemed approved unless Owner makes written objection thereto
         within five (5) working days after receipt thereof.

2.4      The drawings, specifications and other documents furnished by
         Designer-Builder are instruments of service and are the property of
         Designer-Builder whether or not the work for which they are made is
         commenced. Drawing, specifications and other documents furnished by
         Designer-Builder shall not be used by Owner or other prospects, for
         completion of the work by others, except by written agreement relating
         to use, liability and compensation.

2.5      Submission or distribution of documents to meet official regulatory
         requirements or for other purposes in connection with the work is not
         to be construed as publication in derogation of the Designer-Builder's
         or its architect's common law copyrights or other reserved rights.
         Owner shall own neither the documents nor the copyrights.

ARTICLE 3:  SCOPE OF THE WORK

3.1      The Designer-Builder shall provide all necessary design services and
         furnish all necessary supplies, materials and equipment and all
         necessary labor and service required for the design and construction of
         the project to completion to Owner's satisfaction in accordance with
         the contract documents.

3.2      The design services to be provided by Designer-Builder under this
         contract shall cover all of the following to the extent required for
         the performance of the work; as defined in the "Concept Design
         Program".

3.2.1    Preparation of working drawings and specifications setting forth in
         detail the requirements for the execution and completion of the work.

3.2.2    Review of all shop drawings, samples and other submissions for
         conformance with the design concept of the work and for compliance with
         the drawings and specifications.

3.3      The Designer-Builder shall not be liable to Owner or otherwise
         responsible for damage or injury to the work or for additional costs or
         delays in the performance of the work arising out of or caused by
         concealed, latent or unforeseen surface or sub-surface conditions:  (i)
         differing from those indicated in the contract documents, or (ii) not
         specifically disclosed to Designer-Builder in writing prior to the
         commencement of the work.

3.4      The Designer-Builder shall not be liable to Owner or otherwise
         responsible for damage or injury to the work or for additional costs or
         delays in the performance of the work arising out of or caused by
         reason of the Designer-Builder relying upon or acting upon incorrect or
         inaccurate written information furnished the Designer-Builder by Owner
         or its agents and representatives.

3.5      See Appendix G

ARTICLE 4:  COMMENCEMENT AND COMPLETION

4.1      The work to be performed under this contract shall be commenced
         following the execution of this contract and shall be substantially
         completed at a date to be jointly agreed upon. Those areas as
         designated in the Milestone Schedule and Appendix F, Significant
         Milestones shall be completed on those dates, and in the manner
         described.

ARTICLE 5:  CONTRACT SUM

5.1      The owner shall pay the Designer-Builder for the performance of the
         work, subject to additions and deductions by change order as provided
         in Article 12, in current funds, the contract sum of Two Million Seven
         Hundred Sixty One Thousand Three Hundred Thirty Eight and No/100
         Dollars ($2,761,338.00).  The said contract sum shall cover the entire
         charge for design and construction services as set forth in the
         Appendices.  The said
<PAGE>
 
         contract sum is a GMP (Guaranteed Maximum Price) with the
         Designer-Builders Fees Fixed and a Cost of Savings Split of 50-50
         between the Owner and the Designer-Builders on the balance of the
         contract.

5.2      The contract sum is comprised of the following:

         A.  Phase 1 Construction
         B.  Critical Support Equipment

5.3      All additions and/or deductions not covered by change orders will be
         paid from the cost of savings on a line item basis.

5.4      Per agreement the Owner shall pay the Designer-Builder an amount equal
         to Twenty percent (20%) ($552,268.00) of the contract sum upon
         execution of the contract.

ARTICLE 6:  PROGRESS PAYMENTS

6.1      On or before the 15th day of the first full month following the
         commencement of the work and continuing thereafter on or before the
         15th day of each succeeding month, Designer-Builder shall submit to
         Owner an invoice for payment and made a part hereof, covering all work
         performed during the preceding month, including all work performed
         pursuant to change orders.

6.2      The invoice for payment shall show:

6.2.1    Charge for all design and construction work performed during the
         preceding month, including the value of construction material and
         equipment, the payment of which Designer-Builder is liable for, whether
         or not such construction material is delivered to the project site.

6.3      Within twenty (20) days after submission of the invoice for payment,
         Owner shall make a progress payment to Designer-Builder in an amount
         equal to the aggregate sum of the following:

6.3.1    100% of the aggregate amount of the charge for design, construction and
         equipment as shown on the invoice for payment.

6.3.2    Interest at the rate of one and one-half (1-1/2%) percent per month
         shall be paid on the unpaid balance of any invoice for payment, not
         paid by the Owner within twenty (20) days from the date of receipt
         thereof. Such interest shall be in addition to the contract sum to be
         paid Designer-Builder pursuant to this agreement.

6.4      Each invoice for payment shall contain Designer-Builder's
         certifications that the work described in the invoice has been
         completed in accordance with the contract documents, that all due items
         are paid for, for which previous certificates were issued and payments
         received, and that the amount of the payment shown on the invoice now
         due Designer-Builder.

ARTICLE 7:  PAYMENT TO DESIGNER-BUILDER FOLLOWING SUBSTANTIAL COMPLETION

7.1      When the Designer-Builder determines that the work or a designated
         portion thereof is substantially complete, the Designer-Builder shall
         prepare and submit to Owner a certificate of substantial completion,
         which shall fix the date of substantial completion.  The
         Designer-Builder shall attach to the certificate a list of items to be
         completed or corrected by Designer-Builder before final payment.  The
         Owner shall have seven (7) days after receipt of the certificate of
         substantial completion to make written objection thereto.  Any
         objection on the part of the Owner shall be in such specific detail as
         to adequately apprise Designer-Builder of the basis for the objection.
         In the event Owner does not make objection within the prescribed time,
         the work shall be deemed to be substantially complete as of the date
         specified in the certificate of substantial completion.

ARTICLE 8:  FINAL PAYMENT
<PAGE>
 
8.1      The Owner shall make final payment within thirty (30) days after
         completion of the work, provided the contract be then fully performed.

8.2      The making of final payment shall constitute a waiver of all claims by
         Owner except those arising from: (1) unsettled claims; (2) faulty or
         defective work appearing after substantial completion; and (3) failure
         of the work to comply with requirements of the contract documents.

8.3      Acceptance of final payment shall constitute a waiver of all claims by
         Designer-Builder except those previously made in writing and identified
         by Designer-Builder as unsettled at the time of final payment.

ARTICLE 9:  DESIGNER-BUILDER'S GUARANTY

9.1      Designer-Builder, subject to the provisions of 9.2 hereof, guarantees
         that the work shall be performed in a skillful and workmanlike manner,
         free from defects in material and workmanship and in conformance with
         the contract documents.  This guaranty is expressly in lieu of all
         other guaranties and warranties, express or implied, including any
         warranties of merchantability and fitness.  Designer-Builder's
         liability for its guaranty hereunder shall be limited to remedying, any
         defect in material and workmanship approximately resulting from the
         failure of Designer-Builder to perform the work in a skillful and
         workmanlike manner, provided however: (i) that such defect shall
         manifest itself on or before the expiration of the first year next
         following the date of substantial completion, and (ii) that Owner shall
         give notice in writing to Designer-Builder of such defect on or before
         the expiration of the first year next following the date of substantial
         completion.  In lieu of remedying such defect in the work,
         Designer-Builder, with the concurrence of Owner, may pay Owner the cost
         of repair thereof.

9.2      Designer-Builder does not guarantee or warrant, either expressly or
         impliedly, the materials in or workmanship of supplies, materials,
         equipment or machinery manufactured by third parties and furnished and
         installed by Designer-Builder in the performance of the work, but
         Designer-Builder shall endeavor to obtain from all vendors and
         suppliers and assign to Owner the customary warranties and guaranties
         of such vendors and suppliers with respect thereto and Designer-Builder
         shall, at the sole cost and expense of Owner, render reasonable
         assistance to Owner when requested in order to enable Owner to enforce
         such warranties and guaranties by the third party manufacturers or
         suppliers.

ARTICLE 10:  RESPONSIBILITIES OF OWNER

The Owner, at its sole cost and expense, shall:

10.1     Cooperate with the Designer-Builder in all respects.

10.2     Designate in writing a person to act as Owner's Representative with
         respect to the work to be performed under this agreement and such
         person shall have complete authority to transmit instructions to the
         Designer-Builder through Designer-Builder's Representative, receive
         information and interpret and define Owner's policies and decisions
         with respect to all aspects of the work covered by this agreement.

10.3     Provide full information with respect to the scope of the work to be
         performed by Designer-Builder.

10.4     Give prompt written notice to Designer-Builder whenever the Owner
         observes or otherwise becomes aware of any defect in the work covered
         by this agreement.

10.5     Guarantee access to and make all provisions for the Designer-Builder to
         enter upon public and private lands as required for the
         Designer-Builder to perform its work under this agreement.

10.6     Make available a convenient and adequate source of water and
         electricity and furnish telephone service and all other utilities
         required for the performance of the work.

10.7     Furnish all property and topographic surveys describing the physical
         characteristics and legal limits of the job site and necessary utility
         locations at the job site required for the performance of the work.

10.8     Furnish necessary documentation engineering structural suitability of
         existing floor slabs required for the performance of the work.

10.9     Provide at the job site for the benefit and use of Designer-Builder in
         the performance of the work, sufficient
<PAGE>
 
         office space, parking space and storage space for materials and
         construction equipment.

10.10    Make application to all municipal jurisdictional agencies and obtain
         all governmental approvals, permits, license and variances required for
         the performance of the work.

10.11    Not cause any other construction to be undertaken in the immediate area
         of the job site where the work is to be performed by Designer-Builder
         under this agreement without the consent of Designer-Builder.

10.12    Owner to provide tax exempt status certification to Designer-Builder.

ARTICLE 11:  RESPONSIBILITIES OF DESIGNER-BUILDER

The Designer-Builder shall:

11.1     Cause the work to be performed in accordance with the contract
         documents, using its best skill and attention.

11.2     Provide and pay for all labor, materials, equipment, tools,
         construction equipment and machinery, transportation and other
         facilities and services necessary for the execution and completion of
         the work.

11.3     At all times during the performance of the work, keep the premises free
         from accumulation of waste materials or rubbish caused by its
         operations.  At the completion of the work, Designer-Builder shall
         remove all its waste materials and rubbish from and about the job site
         as well as its tools, construction equipment, machinery and surplus
         materials and shall leave the job site "room clean" or its equivalent.

11.4     Assist Owner in making application to all municipal jurisdictional
         agencies for the purpose of obtaining all governmental approvals,
         permits, licenses and variances required for the performance of the
         work, provided nevertheless, that Owner shall be responsible for the
         actual obtainment of all such approvals, permits, licenses and
         variances.

11.5     Obtain and furnish to the Owner all waivers of lien, including but not
         limited to, waiver of mechanics liens.

ARTICLE 12:  CHANGES IN THE WORK

12.1     The Owner, without invalidating the contract, may order changes in the
         work consisting of additions, deletions or modifications and the
         contract sum and the time for the completion of the work shall be
         adjusted accordingly. All such changes in the work shall be authorized
         by a construction change directive and thereafter confirmed by a change
         order in the manner hereinafter provided for.

12.2     In the event that any building landlord of the owner or any
         governmental official orders changes in the scope of work, the contract
         sum and the time for the completion of the work shall be adjusted
         accordingly. All such changes in the work shall be authorized by a
         construction change directive and thereafter conformed by a change
         order in the manner hereinafter provided for.

12.3     The Designer-Builder shall not be required to proceed with any
         additions, deletions or modifications to the work unless pursuant to a
         construction change directive. Should the work to be performed by
         Designer-Builder under any construction change directive result in an
         increase in the cost of the work, the Owner shall be obligated to pay
         Designer-Builder the total cost of the additional work.

12.4     The cost or net credit to the Owner resulting from a change in the work
         as above provided shall be confirmed by a change order.  Thereupon, the
         time for the completion of the work shall be adjusted accordingly. The
         contract sum shall be adjusted upwards or downwards by the amount of
         any additional cost to Owner or credited to Owner resulting from any
         change in the work caused by change order. The refusal by Owner to
         execute a change order shall not relieve Owner of its obligation to pay
         Designer-Builder the full cost of any additional work performed by
         Designer-Builder pursuant to a construction change directive.
<PAGE>
 
ARTICLE 13:  INDEMNIFICATION BY DESIGNER-BUILDER

13.1     Designer-Builder, within the limited of its insurance coverage as
         provided in Article 16 hereof, shall indemnify and save Owner harmless
         from and against any loss, liability or damages (including reasonable
         attorney fees, court and/or arbitration expenses) which may be
         sustained by Owner by reason of sickness, disease, bodily injury or
         death to persons or damages to tangible property occurring during the
         performance of the work and resulting from the negligence of
         Designer-Builder, its subcontractors, agents or employees, including,
         but not limited to, damages caused directly or indirectly by any
         substances, conditions, elements, material or any combination of the
         foregoing either intentionally or unintentionally emitted or released
         or caused to be emitted or released by Designer-Builder, its
         subcontractors, agents or employees from or at work site.

13.2     The Designer-Builder shall indemnify and save harmless Owner from all
         costs, fees, damages and expenses arising out of or resulting from any
         charge or encumbrance in the nature of a laborer's, mechanic's or
         material man's lien asserted by a party or parties other than Designer-
         Builder in connection with the performance of the work.

ARTICLE 14:  INDEMNIFICATION BY OWNER

14.1     Owner shall indemnify and save Designer-Builder harmless from and
         against any loss, liability or damages (including reasonable attorney
         fees, court and/or arbitration expenses) which may be sustained
         by Designer- Builder by reason of sickness, disease, bodily injury or
         death to persons or damages to tangible property occurring during the
         performance of the work and resulting from the negligence of Owner, its
         subcontractors, agents or employees.

ARTICLE 15:  PATENT INDEMNIFICATION

15.1     The Owner shall not cause Designer-Builder to use any design, process
         or equipment which would infringe upon any patent right held by any
         third party.

15.2     Owner shall indemnify and save Designer-Builder harmless from and
         against all liability, damages and expenses arising out of any suit or
         action brought against Designer-Builder for use of any design, process
         or equipment required by the Owner, based upon a claim that any design,
         process or equipment incorporated in the work infringes upon any
         invention, design, process or device which is the subject of a patent.

ARTICLE 16:  DESIGNER-BUILDER INSURANCE

16.1     The Designer-Builder shall purchase and maintain all of the insurance
         described in 16.1.1 through 16.1.3 hereof, for not less than the limits
         of liability therein specified so as to protect Designer-Builder from
         claims under workmen's compensation acts and other employee benefits
         acts, from claims for damage because of bodily injury, including death,
         and from claims for damage to property which may arise out of or result
         from the Designer-Builder's operations under this contract, whether
         such operations be by Designer-Builder or by any subcontractor or
         anyone directly or indirectly employed by any of them.

16.1.1   Workmen's compensation, including occupational disease in accordance
         with the statutory requirements set forth by the state which the work
         is to be performed and employer's liability insurance covering all
         Designer-Builder's employees engaged in the performance of this
         contract in the minimum sum of $500,000.00.

16.1.2   Comprehensive general liability insurance, including Designer-Builder's
         protective liability contractual liability insurance covering death or
         bodily injury with minimum limits of $250,000.00 per person and
         $1,000,000.00 for any one accident and property damage coverage with
         minimum limits of $1,000,000.00 in the aggregate. The contractual
         liability insurance shall insure the hold harmless and indemnification
         agreement contained in 13.1 of this contract.

16.1.3   Comprehensive automobile liability insurance covering Designer-Builder
         for claims arising from owned, hired and non-owned vehicles covering
         death or bodily injury with minimum limits of $1,000,000.00 for any one
         accident and property damage coverage with minimum limits of
         $1,000,000.00 per accident.

16.2     Certificates of insurance covering all of the insurance required to be
         maintained by Designer-Builder shall be filed with the Owner.
<PAGE>
 
ARTICLE 17:  OWNER'S INSURANCE

17.1     Owner, at its own expense, shall obtain and maintain until completion
         of the work, comprehensive general liability insurance and property
         insurance which shall insure against the perils of fire, flooding,
         extended coverage, theft, vandalism and malicious mischief, containing
         a limit of not less than the full amount of the contract sum.  This
         insurance shall include the interest of the Owner, Designer-Builder and
         subcontractors. The loss, if any, under such insurance is to be made
         adjustable with and payable to Owner, Designer-Builder and
         subcontractors, as their interest may appear.  The policy for such
         insurance shall be issued by an insurance carrier authorized to do
         business in the state in which the work is to be performed and shall
         not be canceled or substantially modified without at least thirty (30)
         days advance written notice to the Designer-Builder.

17.2     Certificates of insurance, naming Designer-Builder as an additional
         insured under the above described policies, shall be filed with
         Designer-Builder.

ARTICLE 18:  TERMINATION OF THE AGREEMENT BY OWNER

18.1     The Owner, may, upon ten (10) days written notice and upon the
         occurrence of any event of default by Designer-Builder as provided in
         18.2, terminate this agreement. Upon receipt of such notice of
         termination, Designer-Builder shall also take steps necessary for its
         orderly and safe disengagement from and protection of the work.

18.2     The Designer-Builder shall be in default under this agreement upon the
         occurrence of any of the following mentioned events:

18.2.1   Insolvency or bankruptcy of Designer-Builder or the making of any
         assignment for the benefit of creditors, or the filing of any petition
         for bankruptcy or reorganization by Designer-Builder.

18.2.2   The willful breach of any material provisions of this agreement by
         Designer-Builder and the failure by Designer-Builder to take prompt
         action to remedy same with ten (10) days of the receipt of written
         notice from Owner.

18.3     In the event of Designer-Builder's default, Owner shall have the right
         to terminate the employment of Designer-Builder to take possession of
         the work and of all materials, tools and appliances thereon with the
         right to their continued use, without obligation, until such time as
         the work is completed, and to finish the work by any reasonable method
         Owner may deem expedient.

18.4     Should Owner terminate the contract, Owner shall pay Designer-Builder a
         sum equal to the value of the total work completed to date of
         termination, including:  (i) all design services, and (ii) all
         construction work.

ARTICLE 19:  TERMINATION OF THE AGREEMENT BY DESIGNER-BUILDER

19.1     The Designer-Builder may, upon the occurrence of any event of default
         by Owner as provided in 19.3 and upon ten (10) days written notice to
         Owner, terminate this agreement without prejudice to any legal remedies
         or rights it may possess, and recover from Owner payment for the entire
         unpaid balance of the aggregate sum due Designer-Builder for the
         performance of the work completed as of the date of termination,
         including the cost of all supplies, materials, equipment and design
         services, the cost of which Designer-Builder shall be legally obligated
         to satisfy.

19.2     In addition to such sums as due Designer-Builder under the provisions
         of Article 5, Owner shall also pay Designer-Builder:

19.2.1   All charges for actual costs incurred by Designer-Builder to date of
         termination, including all costs and expenses incurred for the orderly
         and safe disengagement from and protection of the work.

19.2.2   All cancellation charges which Designer-Builder shall become obligated
         to pay any subcontractor or material man of Designer-Builder.

19.2.3   The amount of such damages as Designer-Builder shall become obligated
         to pay any subcontractor or material man of Designer-Builder.
<PAGE>
 
19.3     The Owner shall be in default of this agreement upon the occurrence of
         any of the following mentioned events:

19.3.1   Insolvency or bankruptcy of Owner or the making of any assignment for
         the benefit of creditors or the filing of any petition for bankruptcy
         or reorganization by Owner.

19.3.2   The willful breach of any provision of this agreement by Owner and the
         failure by Owner to remedy same within ten (10) days of the receipt of
         written notice thereof from Designer-Builder.

19.3.3   The willful failure without cause to make payment on any application
         for payment within thirty (30) days from submission thereof.  Should
         Owner in good faith dispute a portion of any application for payment,
         it shall still be required to make timely payment of the undisputed
         portion of such application for payment and its failure to do so shall
         constitute an act of default.

19.4     In lieu of terminating the contract as above provided, upon the
         happening of any of the events above mentioned, Designer-Builder may
         stop the performance of the work or the progress of the work until such
         time as the default is remedied without prejudice to any other legal
         remedy or right it may possess.  The election by Designer-Builder to
         stop the work as herein provided shall not be deemed a waiver of
         Designer-Builder's right to terminate the agreement.

19.5     All monies due Designer-Builder upon termination of this agreement
         shall bear interest at the rate of 1-1/2 percent per month, calculated
         from the date of termination and all such interest shall belong
         exclusively to Designer-Builder.

ARTICLE 20:  DISPUTES

20.1     All claims, disputes or other matters in controversy arising out of or
         relating to this agreement shall be determined in the manner provided
         for in Appendix E attached hereto and made a part hereof.

ARTICLE 21:  DELAYS

21.1     Designer-Builder shall not be responsible for any delay in the
         performance or progress of the work or liable for any costs or damages
         sustained by Owner resulting from such delay caused by any act or
         neglect of the Owner or Owner's Representative, or by any employee of
         Owner, or by any third party acting as the agent, servant or employee
         of the Owner, or by changes ordered in the work, or by labor disputes,
         including but not limited to strikes, slowdowns, job actions, picketing
         and secondary boycotts, or by fire or other casualty loss, or by
         unusual delay in transportation, or by acts of God, or as a result of
         compliance with any order or request of any federal, state or municipal
         governmental authority or any person purporting to act therefore, or by
         acts of declared or undeclared war, or by public disorder, riot or
         civil commotion, or by any other cause beyond the control and without
         the fault or negligence of Designer-Builder. In the event of any such
         delay, Designer-Builder shall proceed with due diligence to alleviate
         such delay and continue the performance of all obligations hereunder.
         The time during which Designer-Builder is delayed in the performance of
         the work, as herein provided, shall be added to the time for completion
         of the work as set forth in Article 4. All additional costs or damages
         resulting from any delay in the performance or progress of the work
         caused by any act or neglect of the Owner, its agents or
         representatives, shall be borne entirely by the Owner.

ARTICLE 22:  MISCELLANEOUS PROVISIONS

22.1     Any notices required or permitted under this contract shall be deemed
         to be fully given if sent by telecopy, messenger service or certified
         mail.

         If to the Owner, addressed:    If to the Designer-Builder addressed:

         Brain Addy                     Raymond Noesges
         Focal Communications           Data Center Design and Development
         200 North LaSalle Street       630 North Court
         Chicago, Illinois 60601        Palatine, Illinois 60067
<PAGE>
 
22.2     It is agreed between the parties hereto that the interpretation and
         enforcement of this agreement shall be in conformity with the laws of
         the State of Illinois.

22.3     In the event one or more, but not all of the provisions of this
         agreement are declared unlawful and/or unenforceable by a court of
         competent jurisdiction, such determination shall not affect the
         legality or enforce ability of the remainder of the terms hereof.

22.4     This agreement may be executed in several counterparts, each of which
         so executed shall be deemed to be an original, and such counterparts
         shall, together, constitute and be one and the same agreement.

22.5     This agreement shall inure to the benefit of and be binding upon the
         parties hereto and their successors and assigns.

22.6     The Owner and Designer-Builder, by and through their respective
         signatories to this agreement, each represent to the other that they
         are authorized to enter into this agreement.

ARTICLE 23:  OFFER OF EMPLOYMENT

23.1     Owner and Designer-Builder mutually agree that each will not offer
         employment to, nor accept for employment, the employees of the other
         party for a period of six (6) months after final payment and after the
         completion of such other assignments as may follow arising out of this
         contract.

IN WITNESS WHEREOF, the parties hereto have caused these present to be signed by
their proper corporate officers and have affixed their corporate seals hereto
the day and year first above written.

ATTEST:

Focal Communications
200 North LaSalle Street
Chicago, Illinois 60601


                            By Brian F. Addy             1/29/99
                              -----------------------  -----------
                              Duly Authorized Officer      Date

Data Center Design and
Development Corporation
630 North Court
Palatine, Illinois 60067


                            By Raymond Noesges           1/29/99
                              -----------------------  -----------
                              Duly Authorized Officer      Date
<PAGE>
 
                                   Appendix A

                              FOCAL COMMUNICATIONS
                                    Info Mart
                                   Dallas, Tx.
                                Project No:98-149

General Conditions                                                     131,886
         Includes; field supervision, project management, accounting
         & clerical support, project clean up, dumpsters, insurance,
         permit allowance, site materials and services.

Demolition                                                              14,240
         Includes; selective demolition of walls, doors, hardware,
         acoustical ceiling, glazing, mechanical and electrical.

Premium Time (Allowance)                                                40,000

Cutting and Patching (Allowance)                                         5,000

Site Work                                                                7,708
         Includes; generator pad, excavation, fill and landscape
         restoration.

Structural Steel                                                        50,200
         Includes; installation structural steel condenser rack on
         roof, structural steel battery support in power room,
         rigging and crane time.

Millwork                                                                14,300
         Includes; break room cabinets and counters, copy room
         cabinets and counters.

Door, Frames and Hardware                                               33,880
         Includes all hollow metal and wood doors, frames, hardware,
         Herculite double entry door and rated conference room
         window 4'0"X 6'0".

Access Floor                                                           274,637
         Includes; 2-tiered access floor in Co-Lo area, single
         tiered access floor in switch/transport area.  Both areas
         complete with ramps, stairs, railings, plenum barriers,
         perforated air flow panels and accessories.

GWB                                                                     51,644
         Includes; all new walls, all in fill of existing openings
         as required, extension of rated wall assemblies in various
         areas, all office and demising partitions.

Acoustical Ceilings                                                     47,471
         Includes; clean room acoustical grid ceiling system in
         Co-Lo And Switch/Transport, and 2X2 lay in acoustical
         ceiling system in all finished support area including break
         room and corridor.
<PAGE>
 
Floor Finishes                                                          26,064
         Includes; 18"X18" carpet tile in general office, private
         office, conference and copy rooms.  VCT at landings,
         corridors and break room.  Vinyl wall base as indicated in
         all finished areas.  Painting of exposed concrete floor
         slabs.

Wall Finishes                                                           14,756
         Includes; interior painting of walls, doors and frames.
         Wall coverings as indicated.

Appliances                                                                 800
         Includes; microwave and under counter refrigerator.

Window Treatment (allowance)                                             8,430
         Includes; mini-blinds or coverings as indicated on room
         finish schedule.

Corner Guards                                                            2,400
         Includes; installation of protective guards on all exposed
         corners in the finished areas.

Signage (Allowance)                                                      3,000
         Includes; door, electrical and mechanical equipment signage
         within the finished areas.  Interior/Exterior LOGO or
         directional signage is not included.

HVAC-Mechanical                                                        206,850
         Includes; installation of five (5) 20 ton process air
         conditioners with roof top condensing units, one (1) 15
         ton process air conditioner with roof top condensing unit
         sheet metal duct work for process air conditioners. Roof
         portals for refrigerant lines and future refrigerant lines
         to finished equipment rooms. There are no provisions for
         additional refrigerant lines to unfinished areas.

Fire     Protection-Detection                                          257,230
         Includes; new water line for pre-action and modifications
         to existing wet pipe sprinkler systems. Values and
         manifolds for pre-action systems. Pre-action piping systems
         and zones as indicated. Wet pipe system in common area and
         office areas. Smoke/heat detection with addressable panel
         with tie in to building fire alarm panel.

Plumbing                                                                13,600
         Includes; New/reworked waste and water lines. Condensate
         and humidification lines for processed air conditioners.
         Break room waste and water, fixtures and lines.

Security-Card Access-Monitoring (allowance)                             18,143
         Includes; furnish and install back boxes and conduit;
         installation only of cable, devices and systems furnished
         by other. All terminations are by others.

Voice and Data Cabling (allowance)                                      14,200
         Includes; installation of cabling furnished and terminated
         by others.

<PAGE>
 
Electrical                                                             507,657
         Includes; installation of all electrical equipment,
         grounding, TVSS, service feeder from building 4000A
         vertical bus duct, feeder from new generator system, under
         floor spot leak detection, EPO system, step down
         transformers, all lighting and receptacles, panel boards for
         distribution, all AC power distribution, feeders,
         breakers. Installation of UPS and generator systems. Four
         (4) 4" and Two (2) 2" conduits for fiber and GPS. There is
         no DC conduit, cabling, racking or installation included.
<PAGE>
 
                                   Appendix B



                                 RECAP PROPOSAL
                              FOCAL COMMUNICATIONS
                                   Dallas, Tx
                                January 11, 1999

<TABLE>
<CAPTION>

DESCRIPTION
<S>                                                                                 <C>
GENERAL CONDITIONS                                                                  $131,886.00
DEMOLITION                                                                            14,240.00
PREMIUM TIME (ALLOWANCE)                                                              40,000.00
CUTTING AND PATCHING (ALLOWANCE)                                                       5,000.00
SITE WORK                                                                              7,708.00
STRUCTURAL STEEL                                                                      50,200.00
MILLWORK                                                                              14,300.00
DOORS, FRAMES AND HARDWARE                                                            33,880.00
ACCESS FLOOR                                                                         274,637.00
GWB                                                                                   51,644.00
ACOUSTICAL CEILINGS                                                                   47,471.00
FLOOR FINISHES                                                                        26,064.00
WALL FINISHES                                                                         14,756.00
APPLIANCES                                                                               800.00
WINDOW TREATMENT (ALLOWANCE)                                                           8,430.00
CORNER GUARDS                                                                          2,400.00
SIGNAGE (ALLOWANCE)                                                                    3,000.00
HVAC/MECHANICAL                                                                      206,850.00
FIRE PROTECTION-DETECTION                                                            257,230.00
PLUMBING                                                                              13,600.00
SECURITY-CARD ACCESS-MONITORING (ALLOWANCE)                                           18,143.00
VOICE AND DATA CABLING (ALLOWANCE)                                                    14,200.00
ELECTRICAL                                                                           507,657.00
CRITICAL SUPPORT EQUIPMENT                                                           474,202.00
                                                                                  -------------
                                    SUB-TOTAL                                     $2,218,298.00
                                    CONTINGENCY                                      221,830.00
                                    FEE (OVERHEAD AND PROFIT) 6%                     133,098.00
                                    DESIGN FEE 8%                                    188,112.00
                                                                                ---------------
                                    TOTAL                                         $2,761,338.00
</TABLE>
<PAGE>
 
                                   Appendix C

                         GENERAL CONDITIONS COST SUMMARY
                              FOCAL COMMUNICATIONS
                                   Dallas, Tx.
                                January 11, 1999
<TABLE>
<CAPTION>
DESCRIPTION                              QUANTITY   UNIT      UNIT PRICE        COST
- ----------------------------------------------------------------------------------------
<S>                                         <C>      <C>      <C>             <C>
Superintendent                              60       MD          515.00       30,900.00

Second Shift Supervisor                     12       MD          592.00        7,104.00

Project Coordinator                         45       MH           58.00        2,610.00

Project Manager                             23       MD          634.00       14,582.00

Clean up                                    42       MD          290.00       12,180.00

Dumpsters                                    5       EA.         450.00        2,250.00

Vendor Dumpsters                             3       EA.         450.00        1,350.00

Second Shift Clean up                       10       MD          290.00        2,900.00

Vendor Clean up                             10       MD          335.00        3,350.00

Lay out                                      8       MD          340.00        2,720.00

Misc. materials & supplies                   1       LS        2,500.00        2,500.00

Temporary Protection                         1       LS        1,200.00        1,200.00

Job Site Telephone                           1       LS        1,500.00        1,500.00

Trucking & Deliveries                        1       LS        1,140.00        1,140.00

Final Clean up (Above/below floor)                   LS        2,500.00        2,500.00

Permit (Allowance)                                   LS       20,000.00       20,000.00

Travel                                      15       ea          500.00        7,500.00

Auto                                        12       ea          300.00        3,600.00

Per Diem                                    60       ea          200.00       12,000.00
- ----------------------------------------------------------------------------------------

                                                        TOTAL               $131,886.00
</TABLE>
LEGEND
MD = Man Days
MH = Man Hours
LS = Lump Sum
<PAGE>
 
                                   Appendix D

                              FOCAL COMMUNICATIONS
                                   DALLAS, TX.
                           CRITICAL SUPPORT EQUIPMENT
                               PROJECT NO: 98-149



PROCESS ENVIRONMENTAL CONTROL SYSTEMS                  $ 143,844.00

         - One (1) UH199AUAAM
         - Two (2) UH245AUAAM
         - Three(3) FH245AUAAM
         - Six (6) condensing units
         - Level Three processors
         - Floor stands
         - Spot leak detection
         - Freight, Tax and Start-up

UNINTERRUPTABLE POWER SUPPLY (ups)                       105,941.00

         - One (1) 225k VA (180kW) 600T UPS Module
         - Two (2) battery cabinets with C&D sealed
           batteries rated for 15 minutes at 180kW load
         - One Maintenance Bypass (4 breaker) in
           matching cabinet
         - Freight, Tax and Start-up

EMERGENCY POWER SYSTEM                                   196,719.00

         - One (1) 750 kW Model 3412 diesel engine
           driven package generator
         - One 1200A Automatic Transfer Switch with by pass isolation
           2700 gallon (under belly) fuel tank
         - Sound attenuating housing
         - Freight, Tax and Start-up

                                       Sub-total      $  446,504.00
                                       DCDDC mark-up      27,698.00
                                                      -------------
                                       Total          $  474,202.00
<PAGE>
 
                                   APPENDIX E


RESOLUTION OF DISPUTES BY ARBITRATION

1.       All claims, disputes or other matters in controversy arising out of or
         relating to this agreement shall be determined by three (3)
         arbitrators, one appointed by the Owner, one appointed by the
         Designer-Builder and the third by the arbitrators so appointed.

2.       Notice of demand for arbitration by either party to this agreement
         shall be served in writing upon the other party to this agreement and
         shall be made within sixty (60) days after the dispute has arisen.

3.       Within thirty (30) days after either party shall have given notice of
         demand for arbitration, Owner and Designer-Builder shall each appoint
         his respective arbitrator and give actual notice thereof to the other
         party. If either party shall fail to appoint an arbitrator within the
         aforesaid initial thirty (30)-day period and give actual notice thereof
         to the other party, then said defaulting party shall be deemed to have
         irrevocably waived its right to appoint an arbitrator and the
         arbitrator appointed by the party not in default shall, within thirty
         (30) days next following the expiration of the initial thirty (30) day
         period, appoint the second arbitrator and such appointment shall be
         binding upon the party in default. Within twenty (20) days after the
         appointment if the two (2) arbitrators cannot select a third arbitrator
         within the prescribed twenty (20)-day period, then either party may
         petition the American Arbitration Association to appoint the third
         arbitrator, subject to his acceptance of the procedure for arbitration
         as herein set forth. Neither party shall have the right to appoint an
         arbitrator unless the person to be appointed shall agree to serve as an
         arbitrator subject to the terms and conditions of this article.

4.       The arbitrators, upon their appointment, and after having been duly
         sworn to do their duties with impartiality and fidelity shall proceed
         with all reasonable dispatch to hear and determine the matter in
         dispute and they shall conduct all arbitration proceedings in the state
         in which the work is to be performed. In the event the taking of
         testimony in the arbitration hearing shall not be concluded within
         sixty (60) days after the third arbitrator shall have been selected,
         the arbitrators shall then expedite the hearing of the matter in
         dispute and take testimony on a continuous weekly basis for at least
         thirty-two (32) hours a week until such time as the taking of all
         testimony is completed and both sides have rested.

5.       The owner and Designer-Builder shall each pay the cost and fees of the
         arbitrator they select or who is selected on their behalf and one-half
         of the costs and fees of the third arbitrator.

6.       Whenever possible and to the extent not inconsistent with the
         provisions of this article, the arbitration proceedings shall be
         conducted in accordance with the Construction Industry Arbitration
         Rules promulgated by the American Arbitration Association. However, the
         failure to comply strictly with such Rules shall not be deemed a breach
         of this agreement.

7.       Any decision or award rendered by at least a majority of the
         arbitrators shall be final and judgment may be entered upon it in
         accordance with the laws of the State of Illinois.

8.       It shall be a condition precedent to the institution of any legal
         proceedings by either party against the other that a decision or award
         shall first have been rendered by the arbitrators.
<PAGE>
 
                                   Appendix F

                               MILESTONE SCHEDULE
                                 PROJECT 98-149




Tuesday 5 January 99       Apply for building/demo permit           DCDDC

Tuesday 5 January 99       Submit drawings for Info Mart review     DCDDC

Tuesday 5 January 99       Receive Permits                          DCDDC

Wed/Thurs 6-7 Jan 99       Interview Sub Contractors                DCDDC

Friday 8 January 99        Order Critical Equipment                 DCDDC

Tuesday 19 January 99      Info Mart comments due                   Info Mart

Thursday 21 January 99     Bids Due from Sub Contractors            All

Monday 1 February 99       Begin construction/demo                  Project Team

Monday 1 February 99       Submit Drawings for City review          DCDDC

Monday 1 March 99          UPS/Process air conditioners delivered   Vendors

Monday 15 March 99         Complete Switch Room general             Project Team
                           construction, ready for Nortel switch
                           installation

Monday 12 April 99         Provide power for Nortel equipment       Project Team

Monday 12 April 99         Provide process cooling to switch room   Project Team

Monday 3 May 99            Generator delivered                      Vendor

Monday 3 May 99            Co-Lo ready to accept cabinets           Project team

Monday 7 June 99           Office area ready for occupancy          Project team

Monday 14 June 99          Construction substantially complete      Project team

Monday 21 June 99          Project closeout                            DCDDC/
                                                                    project team
<PAGE>
 
                                   Appendix G


                          ARTICLE 3: SCOPE OF THE WORK


3.5      The Designer-Builder shall be responsible for obtaining all necessary
         documentation required by the Owner evidencing lien free completion of
         the work. Failure to secure such documentation will result in
         non-payment of the contract sum due to the Designer-Builder.

<PAGE>
 
                                                                   EXHIBIT 10.15


                                     LEASE

                                    BETWEEN

           RIVERFRONT OFFICE PARK ASSOCIATES II LIMITED PARTNERSHIP

                                   Landlord



                                      AND



                       FOCAL COMMUNICATIONS CORPORATION

                                    Tenant

                               ONE MAIN STREET,
                           CAMBRIDGE, MASSACHUSETTS
<PAGE>
 
                                     INDEX
                                     -----

<TABLE> 
<S>                                                                                              <C> 
1.       REFERENCE DATA.........................................................................  1 
                                                                                                   
                                                                                                   
2.       DESCRIPTION OF DEMISED PREMISES........................................................  3 
         2.1 Demised Premises...................................................................  3 
         2.2 Appurtenant Rights.................................................................  3 
         2.3 Reservations.......................................................................  3 
         2.4 Roof Antenna; Telecommunications Equipment License.................................  3 
                                                                                                   
                                                                                                   
3.       TERM OF LEASE; OPTION TO EXTEND TERM...................................................  5 
         3.1 Habendum...........................................................................  5 
         3.2 Term Commencement Date.............................................................  5 
         3.3 Option to Extend...................................................................  5 
         3.4 Right of First Offer...............................................................  6 
                                                                                                   
                                                                                                   
4.       CONDITION OF PREMISES; TENANT'S FIT-UP ALLOWANCE; TENANT'S ACCESS......................  6 
         4.1 Condition of Premises..............................................................  6 
         4.2 Tenant Allowance for Fit-Up Work...................................................  6 
         4.3 Tenant's Access....................................................................  7 
                                                                                                   
                                                                                                   
5.       USE OF PREMISES........................................................................  7 
         5.1 Permitted Use......................................................................  7 
         5.2 Prohibited Uses....................................................................  7 
         5.3 Licenses and Permits...............................................................  7 
                                                                                                   
                                                                                                   
6.       RENT...................................................................................  8 
         6.1 Yearly Fixed Rent..................................................................  8 
         6.2 Taxes..............................................................................  8 
         6.3 Operating Expenses.................................................................  8 
         6.4 Tenant's Proportionate Share.......................................................  9 
         6.5 Payment to Mortgagee...............................................................  9 
         6.6 Right to Audit Records.............................................................  9 
                                                                                                
                                                                                                
7.       UTILITIES AND LANDLORD'S SERVICES...................................................... 10
         7.1 Electricity........................................................................ 10
         7.2 Water Charges...................................................................... 11
</TABLE> 
<PAGE>
 
<TABLE> 
<S>                                                                                           <C> 
         7.3 Heat and Air Conditioning.......................................................... 11
         7.4 Additional Heat, Cleaning and Air Conditioning Services............................ 11
         7.5 Repairs and Other Services......................................................... 12
         7.6 Interruption or Curtailment of Services............................................ 12


8.       CHANGES OR ALTERATIONS BY LANDLORD..................................................... 12


9.       FIXTURES, EQUIPMENT AND IMPROVEMENTS - REMOVAL BY TENANT............................... 13
                                                                                                
                                                                                                
10.      ALTERATIONS AND IMPROVEMENTS BY TENANT; RESTORATION TO SHELL CONDITION................. 13


11.      TENANT'S CONTRACTORS - MECHANICS' AND OTHER LIENS - 
         STANDARD OF TENANT'S PERFORMANCE - COMPLIANCE WITH LAWS................................ 14 


12.      REPAIRS AND SECURITY BY TENANT......................................................... 14
                                                                                                   

13.      INSURANCE, INDEMNIFICATION, EXONERATION AND EXCULPATION................................ 15
         13.1 Insurance......................................................................... 15
         13.2 Certificates of Insurance......................................................... 15
         13.3 General........................................................................... 15
         13.4 Property of Tenant................................................................ 16
         13.5 Bursting of Pipes, etc............................................................ 16
         13.6 Repairs and Alterations - No Diminution of Rental Value........................... 17
                                                                                                   
                                                                                                   
14.      ASSIGNMENT, MORTGAGING, SUBLETTING, ETC................................................ 17
         14.1 Restrictions...................................................................... 17
         14.2 Requests to Assign or Sublet...................................................... 17
         14.3 Exceptions........................................................................ 18
         14.4 Excess Rent....................................................................... 18
         14.5 Recapture......................................................................... 18
         14.6 Further Documentation............................................................. 20
         14.7 General........................................................................... 20
                                                                                                   
                                                                                                   
15.      MISCELLANEOUS COVENANTS................................................................ 21
         15.1 Rules and Regulations............................................................. 21
         15.2 Access to Premises - Shoring...................................................... 22 
</TABLE> 
<PAGE>
 
<TABLE> 
<S>                                                                                              <C> 
         15.3 Accidents to Sanitary and Other Systems........................................... 22
         15.4 Signs, Blinds and Drapes.......................................................... 23
         15.5 Estoppel Certificate.............................................................. 23
         15.6 Prohibited Items.................................................................. 23
         15.7 Requirements of Law; Fines and Penalties.......................................... 23
         15.8 Tenant's Acts - Effect on Insurance............................................... 24
         15.9 Hazardous Materials............................................................... 24
         15.10 Miscellaneous.................................................................... 25
                                                                                                  
                                                                                                  
16.      DAMAGE BY FIRE, ETC.................................................................... 25
                                                                                                  
                                                                                                  
17.      WAIVER OF SUBROGATION.................................................................. 26
                                                                                                  
                                                                                                  
18.      CONDEMNATION - EMINENT DOMAIN.......................................................... 27
                                                                                                  
                                                                                                  
19.      DEFAULT................................................................................ 28
         19.1 Conditions of Limitation - Re-entry - Termination................................. 28
         19.2 Damages - Assignment for Benefit of Creditors..................................... 29
         19.3 Damages - Termination............................................................. 29
         19.4 Fees and Expenses................................................................. 30
         19.5 Landlord's Remedies Not Exclusive................................................. 31
         19.6 Grace Period...................................................................... 31
                                                                                                  
                                                                                                  
20.      END OF TERM - ABANDONED PROPERTY....................................................... 31
                                                                                                  
                                                                                                  
21.      RIGHTS OF MORTGAGEES................................................................... 32
         21.1 Superiority of Lease.............................................................. 32
         21.2 Entry and Possession.............................................................. 32
         21.3 Right to Cure..................................................................... 32
         21.4 Prepaid Rent...................................................................... 33
         21.5 Continuing Offer.................................................................. 33
         21.6 Subordination..................................................................... 33
         21.7 Limitations on Liability.......................................................... 33
                                                                                                  
                                                                                                  
22.      QUIET ENJOYMENT........................................................................ 34
                                                                                                  
                                                                                                  
23.      ENTIRE AGREEMENT - WAIVER - SURRENDER.................................................. 34
</TABLE> 
<PAGE>
 
<TABLE> 
<S>                                                                                              <C>  
         23.1 Entire Agreement.................................................................. 34
         23.2 Waiver by Landlord................................................................ 34
         23.3 Surrender......................................................................... 34
                                                                                                   
                                                                                                   
24.      INABILITY TO PERFORM - EXCULPATORY CLAUSE.............................................. 35
                                                                                                   
                                                                                                   
25.      BILLS AND NOTICES...................................................................... 35
                                                                                                   
                                                                                                   
26.      PARTIES BOUND - SEIZING OF TITLE....................................................... 36
                                                                                                   
                                                                                                   
27.      MISCELLANEOUS.......................................................................... 36
         27.1 Separability...................................................................... 36
         27.2 Captions.......................................................................... 37
         27.3 Broker............................................................................ 37
         27.4 Governing Law..................................................................... 37
         27.5 Assignment of Rents............................................................... 37
         27.6 Parking........................................................................... 37
         27.7 Notice of Lease................................................................... 38
         27.8 Financial Statements.............................................................. 38
         27.9 Holding Over...................................................................... 38 
</TABLE> 

EXHIBIT A                  Description of Demised Premises
EXHIBIT B                  Description of Land
EXHIBIT C                  Audit Procedures
EXHIBIT D                  Procedure for Allocation of Costs of
                            Electric Power Usage by Tenants
EXHIBIT E                  Cleaning Specifications
EXHIBIT F                  Rules and Regulations
<PAGE>
 
                              AGREEMENT OF LEASE

          AGREEMENT OF LEASE made as of the 6th day of January, 1999, by and
between RIVERFRONT OFFICE PARK ASSOCIATES II LIMITED PARTNERSHIP, a
Massachusetts limited partnership (hereinafter referred to as "Landlord") and
FOCAL COMMUNICATIONS CORPORATION, a Delaware corporation (hereinafter referred
to as "Tenant").

                             W I T N E S S E T H:

          Landlord hereby leases to Tenant and Tenant hereby hires from Landlord
a portion of the eleventh (11th) floor, as shown on the plan attached hereto as
Exhibit A and made a part hereof (hereinafter referred to as the "Premises" or
- ---------                                                                     
the "Demised Premises") contained in the building known and numbered as One Main
Street, Cambridge, Massachusetts (hereinafter referred to as the "Building").

1.   REFERENCE DATA

     Each reference in this Lease to any of the terms and titles contained in
this Article shall be deemed and construed to incorporate the data stated
following that term or title in this Article.

(1)  Additional Rent:      Sums or other charges payable by Tenant to Landlord
                           under this Lease, other than Yearly Fixed Rent.

(2)  Business Day:         All days except Saturdays, Sundays, and days defined
                           as "Legal Holidays" for the entire state under the
                           laws of the Commonwealth of Massachusetts.

(3)  Consumer Price Index: The United States Department of Labor's Bureau of
                           Labor Statistics, Consumer Price Index (1982-
                           1984=100), All Urban Consumers, All Items, Boston,
                           Massachusetts, or the successor to such index.

(4)  Land:                 The parcel of land described on Exhibit B attached
                                                           ---------         
                           hereto and made a part hereof.

(5)  Landlord's Address:   c/o Codman Management Company, Inc., One Main
                           Street, Cambridge, Massachusetts 02142.

(6)  Mortgage:             A mortgage, deed of trust, trust indenture, or other
                           security instrument of record creating an interest in
                           or affecting title to the Land or Building or any
                           part thereof, including the leasehold mortgage, and
                           any and all renewals, modifications, consolidations
                           or extensions of any such instrument.
                           
<PAGE>
 
(7)  Mortgagee:           The holder of any Mortgage.
 
(8)  Parking Spaces:      Thirteen (13).
 
(9)  Property:            The Land and Building.
 
(10) Rent:                Yearly Fixed Rent and Additional Rent.
 
(11) Rentable Area of the
     Demised Premises:    13,274 square feet.
 
(12) Tenant's Address:    One Main Street, Cambridge, Massachusetts 02142.
 
(13) Term Commencement
     Date:                As defined in Section 3.2.
 
(14) Term of This Lease:  As defined in Section 3.1.
 
(15) Termination Date:    As defined in Section 3.1.

(16) Use of Demised
     Premises:            General office purposes, computer and
                          telecommunications operations, and all other uses
                          incidental and related thereto consistent with that in
                          first-class office buildings in the greater Boston
                          area (the "Permitted Use").

(17) Yearly Fixed Rent:   (a)  During the first five (5) years of the Term of
                               ----------------------------------------------
                               this Lease:
                               ---------- 

                               $530,960.00 per annum, based upon a rental rate
                               of $40.00 per rentable square foot per annum.

                          (b)  During the sixth (6th) year through and including
                               -------------------------------------------------
                               the tenth (10th) year of the Term of this Lease:
                               ----------------------------------------------- 

                               An amount per annum equal to the product of (i)
                               $530,960.00 multiplied by (ii) a fraction, the
                               denominator of which shall be the most recent
                               Consumer Price Index figure published prior to
                               the Term Commencement Date, and the numerator of
                               which shall be the Consumer Price Index for the
                               month of December, 2003 (or if not published for
                               December, 2003, the then most recent previous

                                       2
<PAGE>
 
                              month for which the Index is published).


2.   DESCRIPTION OF DEMISED PREMISES

     2.1 Demised Premises.  The Demised Premises are that portion of the
         ----------------                                                  
Building as described above (as the same may from time to time be constituted
after changes therein, additions thereto and eliminations therefrom pursuant
hereto).

     2.2 Appurtenant Rights.  Tenant shall have, as appurtenant to the
         ------------------                                              
Demised Premises, (a) rights to use in common, subject to reasonable rules from
time to time made by Landlord of which Tenant is given notice, those common
roadways, walkways, elevators, hallways and stairways necessary for access to
that portion of the Building occupied by the Demised Premises, (b) the sole and
exclusive right to use and maintain the dedicated electric riser, panel board,
and related switching equipment servicing the 11th floor switch room, and (c)
the sole and exclusive right to use and maintain the chiller water plant serving
the Demised Premises located in part on the 14th floor and in part on the roof
of the Building.  Tenant shall also be provided by Landlord, such space on the
roof of the Building, or elsewhere if acceptable to Landlord and Tenant, as
shall be reasonably necessary for the placement of mechanical equipment
necessary to serve the heating, ventilating and emergency back-up air
conditioning system of the Tenant for the Demised Premises and for Tenant's
computer operations, and such additional rights of access thereto from the
Demised Premises for the purpose of installing, repairing and maintaining same;
provided, however, that if during the Term of this Lease, Tenant's mechanical
and equipment requirements to serve the heating, ventilating and air
conditioning system of the Demised Premises and for Tenant's computer operations
change such that the space then provided by Landlord to Tenant for such purposes
is no longer required by Tenant, then, in such event, Tenant shall so notify
Landlord in writing, and such space shall revert back to Landlord with Tenant
relinquishing any claim or right of access thereto.

     2.3 Reservations.  All the perimeter walls of the Demised Premises except
         ------------                                                           
the inner surfaces thereof, any balconies, terraces or roofs adjacent to the
Demised Premises, and any space in or adjacent to the Demised Premises used for
shafts, stacks, pipes, conduits, wires and appurtenant fixtures, fan rooms,
ducts, electric or other utilities, sinks or other building facilities, and the
use thereof, as well as the right of access through the Demised Premises for the
purpose of operation, maintenance, decoration and repair as hereinafter
provided, are expressly reserved to Landlord.

     2.4 Roof Antenna; Telecommunications Equipment License.  (a) Landlord
         --------------------------------------------------                 
grants to Tenant a license during the Term of this Lease, and only during the
Term of this Lease, subject to the terms and conditions of this Lease, at
Tenant's cost and expense, to install, operate and maintain on the roof of the
Building, at a location and within an area (the "Licensed Roof Area") designated
by Landlord, a small GPS antenna (the "Licensed Antenna").  Tenant, at its cost
and expense, shall be responsible for the preparation and submission to Landlord
of architectural, electrical and mechanical construction drawings, plans and
specifications (collectively, the "Plans") necessary for the configuration and
installation of the Licensed Antenna.  The Plans shall be subject to

                                       3
<PAGE>
 
Landlord's prior written approval, which approval shall not be unreasonably
withheld or delayed. Tenant shall be responsible at the cost and expense for
obtaining all licenses, permits and consents necessary to undertake and complete
the construction of the work contemplated by the Plans. Tenant shall be
responsible at its cost and expense for the construction of all improvements
contemplated by the Plans (the "Improvements"), which shall include appropriate
lightning protection on the Licensed Roof Antenna, provided that all contractors
and construction shall be subject to Landlord's prior written approval, which
approval shall not be unreasonably withheld or delayed, and, provided further
that Landlord shall have the right (but not the obligation) to supervise all
construction, installation, maintenance or repair work undertaken by Tenant
under such license. In no event shall Tenant's construction of the Improvements
pursuant to the Plans result in any penetration of the roof or roof membrane of
the Building (i.e. Tenant shall utilize the existing weather head) unless
otherwise expressly agreed to in writing by Landlord and then only by a
contractor designated by Landlord. On or before the Termination Date, Tenant, at
its sole and expense, shall remove the Improvements and repair any damage to the
Building (including, without limitation, the roof) occasioned by said
installation and/or removal. The Licensed Roof Area shall be used by Licensee
solely for the operation, maintenance and installation of Improvements and for
no other purposes. If any governmental license or permit shall be required for
the proper and lawful conduct of Tenant's business, and if the failure to secure
such license or permit would in any way adversely affect Landlord, Tenant, at
Tenant's cost and expense, shall duly procure and thereafter maintain and remain
in compliance with the terms and conditions such license or permit.

          (b) Subject to the terms and conditions of this Lease, Landlord grants
to Tenant a license during the Term of this Lease, to install, operate and
maintain such telecommunications equipment, cables, junction boxes and not more
than four (4) 4" conduits (collectively, "Telecommunications Equipment and
Cabling") within dedicated portions of the Building's riser systems and utility
areas of the Building as shall be necessary to provide telecommunications
services and point-to-point transmission to tenants and occupants of the
Building.  As of the Commencement Date there are currently two (2) 4" conduits
that may be used by Tenant and Landlord agrees that Tenant shall have the right
to install an additional two (2) additional 4" conduits (the "Additional
Conduits") for a total of four (4) 4" conduits that may be used by Tenant.  The
installation, operation and maintenance of such Telecommunications Equipment and
Cabling shall be subject in each instance to Landlord's prior written approval,
which approval shall not be unreasonably withheld or delayed.  Tenant shall at
all times install, maintain and operate the Telecommunications Equipment and
Cabling in accordance with recognized industry standards and all requirements of
law, regulation or ordinance now or hereafter applicable.  Without limiting the
generality of the foregoing, Tenant shall provide all necessary safeguards
against radiation and other potential health hazards.  The Telecommunications
Equipment and Cabling shall at all times be operated in such a manner as to not
cause interference of any kind with present or future transmissions or reception
of radio, television, telephone or other telecommunications equipment in the
Building.  Tenant shall have the right, at its sole risk and expense, to permit
its customers to locate telecommunications equipment in the Demised Premises,
subject to the provisions of Section 5.2 ("Colocation").  At Landlord's written
election, Tenant, at Tenant's sole cost and expense, prior to the end of the
Term of this Lease, shall remove all

                                       4
<PAGE>
 
Telecommunications Equipment and Cabling located within the Building's riser
systems and utility areas of the Building, provided, however, that
notwithstanding Landlord's election that any such Telecommunications Equipment
and Cabling not be removed (if Landlord shall so elect), Tenant shall have the
right to remove all Telecommunications Equipment and Cabling.

          (c) In no event shall any material or equipment be installed which
shall cause the Demised Premises to be subject to any lien, charge, mortgage or
other encumbrance of any kind whatsoever. Any mechanic's lien filed against the
Building for work claimed to have been done for, or materials claimed to have
been furnished to Tenant, shall be discharged by Tenant within thirty (30) days
thereafter, at the expense of Tenant, by filing with bond required by law or
otherwise. If Tenant fails so to discharge any lien, Landlord may do so at
Tenant's expense and Tenant shall reimburse Landlord for any reasonable expense
or cost incurred by Landlord in so doing within fifteen (15) days after
rendition of a bill therefor. All installations or work done by Tenant under the
licenses granted pursuant to this Section 2.4 shall be at Tenant's own cost and
expense and shall at all times comply with (i) all applicable laws, rules,
orders and regulations of governmental authorities having jurisdiction thereof;
(ii) all applicable orders, rules and regulations of any Board of Fire
Underwriters, or any other body hereafter constituted exercising similar
functions, and governing insurance rating bureaus; and (iii) the Plans. Tenant
shall promptly repair all damage to the Building or any part thereof or any
personal property therein arising from any activities conducted by or on behalf
of Tenant pursuant to the licenses granted pursuant to this Section 2.4.

3.   TERM OF LEASE; OPTION TO EXTEND TERM; RIGHT OF FIRST OFFER

     3.1 Habendum.  TO HAVE AND TO HOLD the Demised Premises for a term of
         --------                                                            
ten (10) years commencing on January 6, 1999 and ending on the day immediately
prior to the tenth (10th) anniversary thereof (the "Term of this Lease"), or on
such earlier date upon which said Term may expire or be terminated pursuant to
any of the conditions of limitation or other provisions of this Lease or
pursuant to law (which date for the termination of the term hereof shall
hereafter be called the "Termination Date").

     3.2 Term Commencement Date.  The Term Commencement Date shall be
         ----------------------                                          
January 6, 1999.

     3.3 Option to Extend.  Tenant may extend the Term of this Lease for up to
         ----------------                                                       
two (2) additional five (5) year period(s) by giving notice to Landlord of its
election to extend at least fourteen (14) months prior to the end of the
original Term or the end of the first five year extension period, as the case
may be.  The Yearly Fixed Rent payable by Tenant with respect to each such
extension period shall be equal to the greater of (a) the then fair market
                                   --------------                         
rental value of the Demised Premises for use for the Permitted Use, or (b) (i)
                                                                    --        
the Yearly Fixed Rent for calendar 2008, in the case of determination of the
Yearly Fixed Rent payable with respect to the first five (5) year extension
period and (ii) the Yearly Fixed Rent for calendar 2013, in the case of
determination of the Yearly Fixed Rent payable with respect to the second five
(5) year extension period.  As used herein, "fair market rental value" shall
mean (1) as the same may be mutually

                                       5
<PAGE>
 
agreed by Landlord and Tenant; provided, however that (2) if they have not so
agreed in writing within two (2) months following the exercise of the option
then said fair market value shall be determined by appraisers, one to be chosen
by Landlord, one to be chosen by Tenant, and a third to be selected by the two
first chosen. The unanimous written decision of the two first chosen, without
selection and participation of a third appraiser, or otherwise the written
decision of a majority of three appraisers chosen and selected as aforesaid,
shall be conclusive and binding upon Landlord and Tenant. Landlord and Tenant
shall each notify the other of its chosen appraiser within thirty (30) days
following expiration of the aforesaid two (2) month period and, unless such two
appraisers shall have reached a unanimous decision within seventy-five (75) days
from said expiration, they shall within a further fifteen (15) days elect a
third appraiser and notify Landlord and Tenant thereof. Landlord and Tenant
shall each bear the expense of the appraiser chosen by it and shall equally bear
the expense of the third appraiser (if any).

     3.4 Right of First Offer.  In the event that at any time during the Term
         --------------------                                                  
of this Lease any rentable space on the eleventh (11th) floor of the Building
then occupied by COM/Energy Services Company becomes or is to become available
for rental, and in the further event Tenant is not then in default of its
material obligations to Landlord under this Lease, Landlord shall make a written
offer to lease the same to Tenant, stating the Rent that Landlord will accept
(which Rent shall reflect Landlord's judgment as to then fair market rental
value of such space) and all other material terms and conditions of the proposed
lease, and Tenant shall have a right of first refusal to lease such space by
giving notice to Landlord to such effect within fifteen (15) Business Days after
notice of such offer.  If such notice of acceptance by Tenant is not so given,
then Landlord shall be free thereafter to lease such space to a third party on
such terms and conditions as Landlord shall determine.  In any case in which
Tenant shall have waived said right of first refusal, or Tenant shall have
failed to timely exercise such right, then Tenant shall, on request of Landlord,
execute and deliver in recordable form an instrument indicating such waiver or
expiration, which instrument shall be conclusive in favor of all persons relying
thereon in good faith.

4.   CONDITION OF PREMISES; TENANT'S FIT-UP ALLOWANCE; TENANT'S ACCESS

     4.1 Condition of Premises.  The Demised Premises are leased in their
         ---------------------                                             
present "AS IS" condition.  Without limiting the foregoing in any respect,
Tenant hereby acknowledges and agrees that Landlord shall have no responsibility
for, or liability with respect to, the condition and/or operation (or failure to
operate or malfunction) of any electronic and other equipment which may be
located on the Demised Premises on the Term Commencement Date.

     4.2 Tenant Allowance for Fit-Up Work.  Landlord shall provide to Tenant a
         --------------------------------                                       
tenant fit-up cash reimbursement allowance of up to $132,274 ($10 per square
foot) to reimburse Tenant for out-of-pocket costs incurred by Tenant for tenant
fit-up work and tenant improvements to the Demised Premises and associated
architectural and engineering fees, payable to Tenant by Landlord within thirty
(30) days of receipt by Landlord of paid invoices evidencing amounts paid by
Tenant and invoiced by Tenant to Landlord for tenant fit-up work completed prior
to June 1,

                                       6
<PAGE>
 
1999. Tenant shall have the right, subject to Landlord's approval, to install,
at Tenant's cost and expense, window treatments or interior walls to seal and
stabilize the environmental conditions within the technical space in the Demised
Premises. All such tenant fit-up work shall be subject to and accomplished in
compliance with Article 10 of this Lease.

     4.3 Tenant's Access.  Tenant shall be permitted access to the Demised
         ---------------                                                    
Premises immediately following execution of this Lease to undertake tenant fit-
up work and to prepare the Demised Premises for Tenant's occupancy.  Such access
shall be deemed to be pursuant to a license from Landlord to Tenant and shall be
at the risk of Tenant.  In no event shall Tenant interfere with any construction
work being performed by or on behalf of Landlord in or around the Building;
without limiting the generality of the foregoing, Tenant shall comply with all
instructions issued by Landlord's agents relative to the moving of Tenant's
equipment and other property into the Demised Premises and shall pay any
reasonable fees or costs imposed in connection therewith.

5.   USE OF PREMISES

     5.1 Permitted Use.  Except as otherwise agreed by Landlord, Tenant,
         -------------                                                     
during the Term of this Lease, shall occupy and use the Demised Premises for the
Permitted Use set forth in Article 1 and for no other purpose.  Notwithstanding
the foregoing, as long as Tenant continues to operate its business in the
Demised Premises for the Permitted Use, even though no personnel occupy the
Demised Premises, Tenant shall be deemed to have met its obligation hereunder to
occupy and use the Demised Premises.  Service and utility areas (whether or not
a part of the Premises) shall be used only for the particular purpose for which
they are designated.

     5.2 Prohibited Uses.  Tenant shall not use, or suffer or permit the use
         ---------------                                                       
of, or suffer or permit anything to be done in or anything to be brought into or
kept in, the Demised Premises or any part thereof (i) which would violate any of
the covenants, agreements, terms, provisions and conditions of this Lease, (ii)
for any unlawful purposes or in any unlawful manner, or (iii) which, in the
reasonable judgment of Landlord shall in any way (a) impair or tend to impair
the appearance or reputation of the Building, (b) impair or interfere with or
tend to impair or interfere with any of the Building services or the proper and
economic heating, cleaning, air conditioning or other servicing of the Building
or Demised Premises, or with the use of any of the other areas of the Building,
or (c) occasion discomfort, inconvenience or annoyance to any of the other
tenants or occupants of the Building, whether through the transmission of noise
or odors or otherwise.  Without limiting the generality of the foregoing, no
food shall be prepared or served for consumption on or about the Demised
Premises; no intoxicating liquors or alcoholic beverages shall be sold on or
about the Demised Premises; no lottery tickets (even where the sale of such
tickets is not illegal) shall be sold and no gambling, betting or wagering shall
otherwise be permitted on or about the Demised Premises; no loitering shall be
permitted in or about the Demised Premises; and no loading or unloading of
supplies or other material to or from the Demised Premises shall be permitted on
the Land except at times and in locations to be designated by Landlord.  The
Demised Premises shall be maintained in a sanitary condition, and all kept free
of rodents and vermin.  All trash and rubbish shall be suitably stored in the
Demised Premises or

                                       7
<PAGE>
 
other locations designated by Landlord from time to time.

     5.3 Licenses and Permits.  If any governmental license or permit shall
         --------------------                                                  
be required for the proper and lawful conduct of Tenant's business, and if the
failure to secure such license or permit would in any way adversely affect
Landlord, Tenant, at Tenant's expense, shall duly procure and thereafter
maintain such license or permit and submit the same to inspection by Landlord.
Tenant,  at Tenant's expense, shall at all times comply with the terms and
conditions of each such license or permit.

6.   RENT

     6.1 Yearly Fixed Rent.  Tenant shall pay to Landlord, without any set-
         -----------------                                                    
off or deduction, at Landlord's office, or to such other person or at such other
place as Landlord may designate by notice to Tenant, the Yearly Fixed Rent set
forth in Article 1.  All Yearly Fixed Rent shall be paid in equal monthly
installments in advance on or before the first business day of each calendar
month during the Term of this Lease and shall be apportioned for any fraction of
a month in which the Term Commencement Date or the last day of the Term of this
Lease may fall.

     6.2 Taxes.  Tenant shall pay to Landlord as Additional Rent a
         -----                                                     
proportionate share (as defined in Section 6.4) of all real estate taxes
(including without limitation all betterment assessments and charges in lieu of
such taxes and any tax on any fixture (other than a Tenant fixture) installed in
the Building, even if taxed as personal property) imposed against the Building
and the Land in any fiscal tax year, in excess of the amount of said real estate
taxes imposed against the Building and the Land for the fiscal tax year ending
June 30, 1999, prorated with respect to any portion of a fiscal year in which
the term of this Lease begins or ends.  Such payments shall be due and payable
within thirty (30) days after Tenant shall have received a copy of the relevant
tax bills.  If Landlord shall receive any refund of real estate taxes of which
Tenant has paid a portion pursuant to this Section, then, out of any balance
remaining after deducting Landlord's expenses incurred in obtaining such refund,
Landlord shall pay to Tenant the same proportionate share of said balance,
prorated as set forth above.  Tenant shall, if, as and when demanded by Landlord
and with each monthly installment of Fixed Rent, make tax fund payments to
Landlord.  "Tax Fund Payments" refer to such payments as Landlord shall
reasonably determine to be sufficient to provide in the aggregate a fund
adequate to pay, when they become due and payable, all payments required from
Tenant under this Section.  In the event that said tax fund payments are not
adequate to pay Tenant's share of such taxes, Tenant shall pay to Landlord the
amount by which such aggregate is less than the amount of said share, such
payment to be due and payable at the time set forth above.  Any surplus tax fund
payments shall be accounted for to Tenant after payment by Landlord of the taxes
on account of which they were made, and shall be promptly refunded to Tenant.

     6.3 Operating Expenses.  Tenant shall pay to Landlord as Additional Rent
         ------------------                                                     
a proportionate share (as defined in Section 6.4) of all costs and expenses
incurred by Landlord in the operation and maintenance of the Building and the
Land in accordance with generally accepted operational and maintenance
procedures in any calendar year, in excess of the amount of said costs and

                                       8
<PAGE>
 
expenses incurred by the Landlord in the operation and maintenance of the
Building and the Land during the calendar year ending December 31, 1998,
including, without limiting the generality of the foregoing, all such costs and
expenses in connection with (1) insurance, license fees, janitorial service,
landscaping, and snow removal, (2) wages, salaries, management fees, employee
benefits, payroll taxes, on-site office expenses, administrative and auditing
expenses, and equipment and materials for the operation, management, and
maintenance of said Property, (3) any capital expenditure (amortized, with
interest, on such reasonable basis as Landlord shall determine) made by Landlord
for the purpose of reducing other operating expenses or complying with any
governmental requirement, (4) the furnishing of heat, air conditioning,
utilities, and any other service to the common areas of the Building (i.e.,
areas not constituting a part of the demised premises of any tenant in the
Building), (5) the operation and servicing of any computer system installed to
regulate Building equipment, and (6) the furnishing of the repairs and services
referred to in Section 7.3 (the foregoing being hereinafter referred to as
"operating expenses").  As soon as Tenant's share of operating expenses with
respect to any calendar year can be determined, the same will be certified by
Landlord to Tenant and will become payable to Landlord within thirty (30) days
following such certification, subject to proration with respect to any portion
of a calendar year in which the Term of this Lease begins or ends.  Tenant
shall, if, as and when demanded by Landlord and with each monthly installment of
Yearly Fixed Rent, make operating fund payments to Landlord.  "Operating Fund
Payments" refer to such payments as Landlord shall reasonably determine to be
sufficient to provide in the aggregate a fund adequate to pay, when they become
due and payable, all payments required from Tenant under this Section.  In the
event that operating fund payments are so demanded, and if the aggregate of said
operating fund payments is not adequate to pay Tenant's share of operating
expenses, Tenant shall pay to Landlord the amount by which such aggregate is
less than the amount of said share, such payment to be due and payable at the
time set forth above.  Any surplus operating fund payments shall be accounted
for to Tenant after such surplus has been determined, and shall be refunded to
Tenant promptly.

     6.4 Tenant's Proportionate Share.  Tenant's proportionate share of
         ----------------------------                                      
taxes pursuant to Section 6.2 and operating expenses pursuant to Section 6.3,
respectively, shall be 4.07% (13,274 square feet divided by 326,470 square feet)
and 4.12% (13,274 square feet divided by 321,917 square feet), respectively.

     6.5 Payment to Mortgagee.  Landlord reserves the right to provide in
         --------------------                                                
any Mortgage given by it of the Property that some or all rents, issues, and
profits and all other amounts of every kind payable to the Landlord under this
Lease shall be paid directly to the Mortgagee for Landlord's account and Tenant
covenants and agrees that it will, after receipt by it of notice from Landlord
or Mortgagee designating such Mortgagee to whom payments are to be made by
Tenant, pay such amounts thereafter becoming due directly to such Mortgagee
until excused therefrom by notice from such Mortgagee.

     6.6 Right to Audit Records.  Tenant and Tenant's agents upon reasonable
         ----------------------                                               
prior notice may inspect Landlord's books and records with respect to taxes and
operating expenses of the Property as to which Tenant is obligated to pay
Additional Rent to Landlord pursuant to Section 6.2 and

                                       9
<PAGE>
 
Section 6.3, respectively, in accordance with the audit procedures set forth in
Exhibit C attached hereto and made a part hereof. If any such audit reveals that
- ---------
such taxes or operating expenses, as the case may be, were overstated, Landlord
shall reimburse Tenant within thirty (30) days after Landlord has been furnished
with a copy of such audit, the excess amount paid by Tenant to Landlord as a
consequence of such overstatement.

7.   UTILITIES AND LANDLORD'S SERVICES

     7.1 Electricity.  Tenant shall pay to Landlord monthly an amount
         -----------                                                   
reasonably estimated by Landlord to equal Tenant's Allocable Electricity Costs
for the electrical energy that Tenant utilizes for light and power in the
Demised Premises.  "Tenant's Allocable Electricity Costs" as used herein shall
be as determined in accordance with Exhibit D annexed hereto and made a part
                                    ---------                               
hereof.  Landlord shall furnish to Tenant quarterly a statement setting forth in
reasonable detail the particulars relating to Tenant's Allocable Electricity
Costs for the three months to which such a statement relates.  In the event the
estimated payments made by Tenant for said three (3) month period shall be less
than Tenant's Allocable Electricity Costs for said period as set forth in said
statement, Tenant shall promptly remit to Landlord the difference.  In the event
the estimated payments made by Tenant for said three (3) month period exceed
Tenant's Allocable Electricity Costs for said period as set forth in said
statement, such excess shall be refunded by Landlord. Landlord shall not be
liable in any way to Tenant for any failure or defect in the supply or character
of electrical energy furnished to the Demised Premises by reason of any
requirement, act or omission of the public utility serving the Building with
electricity unless due to the act or omission of Landlord. Tenant's use of
electrical energy in the Demised Premises shall not at any time exceed the
capacity of any of the electrical conductors and equipment in or otherwise
serving the Demised Premises.  In order to insure that such capacity is not
exceeded and to avert possible adverse affect upon the Building electrical
services, Tenant shall give notice to Landlord and obtain Landlord's prior
written consent whenever Tenant shall connect to the Building electrical
distribution system any fixtures, appliances or equipment.  If at any time the
electrical service to the Demised Premises is inadequate, in Tenant's reasonable
judgment, for the Permitted Use, Tenant shall have the right, subject to
Landlord's prior written consent which consent shall not be unreasonably
withheld or delayed, to install, at Tenant's sole cost and expense, any
additional feeders or risers reasonably necessary to supply Tenant's electrical
requirements in addition to those originally installed and all other equipment
proper and necessary in connection with such feeders, provided that such
additional feeders and risers are permissible under applicable laws and
insurance regulations and the installation of such feeders or risers will not
cause permanent damage or injury to the Building or cause or create a dangerous
condition or unreasonably interfere with other tenants of the Building.  Tenant
agrees that it will not make any alteration or material addition to the
electrical equipment and/or appliances in the Premises without the prior written
consent of Landlord in each instance first obtained (including, but not limited
to consent with respect to Tenant's contractor), which consent will not be
unreasonably withheld, and will promptly advise Landlord of any alteration or
addition to such electrical equipment and/or appliances.  Tenant, at Tenant's
expense, shall  purchase, install and replace all light fixtures, bulbs, tubes,
lamps, lenses, globes, ballasts and switches used in the Demised Premises.
Notwithstanding the foregoing, Landlord, at its election, may install at
Landlord's cost and

                                       10
<PAGE>
 
expense a separate meter for Tenant's electric usage in which event Tenant shall
thereafter obtain and pay for its electricity directly from the electric utility
servicing the Building.

     7.2 Water Charges.  Landlord shall furnish hot and cold water for
         -------------                                                  
ordinary cleaning, toilet, lavatory and drinking purposes to the extent required
to service facilities shown on the Plans approved by Landlord pursuant to
Section 4.3.  If Tenant requires, uses or consumes water for any purpose other
than for such purposes, Landlord may (i) assess a reasonable charge for the
additional water so used or consumed by Tenant or (ii) install a water meter and
thereby measure Tenant's water consumption for all purposes.  In the latter
event, Landlord shall pay the cost of the meter and the cost of installing any
equipment required in connection therewith, and Tenant shall keep said meter and
installation equipment in good working order and repair, and shall pay for water
consumed, as shown on said meter, together with the sewer charge based on said
meter charges, as and when bills are rendered.  On Tenant's default in making
such payment Landlord may pay such charges and collect the same from Tenant.

     7.3 Heat and Air Conditioning.  Landlord shall, through the equipment of
         -------------------------                                             
the Building furnish to and distribute in the Demised Premises heat and air
conditioning as normal seasonal changes may require on Business Days from 8:00
a.m. to 6:00 p.m. and on Saturdays (other than legal or recognized holidays as
defined in Article 1) from 8:00 a.m. to 12:00 noon when reasonably required for
the comfortable occupancy of the Demised Premises by Tenant.  Tenant agrees to
lower and close the blinds or drapes when necessary because of the sun's
position, whenever the air conditioning system is in operation, and to cooperate
fully with Landlord with regard to, and to abide by all the regulations and
requirements which Landlord may prescribe for the proper functioning and
protection of the heating and air conditioning system.

     7.4 Additional Heat, Cleaning and Air Conditioning Services.
         -------------------------------------------------------   

          (a)  The heating and air conditioning equipment serving the Demised
Premises shall be designed so as to permit Tenant to obtain heat and air
conditioning on days and at times other than as set forth in Section 7.3.
Tenant's use of such additional heat and air conditioning shall be gauged on the
meter referred to in Section 7.1 or otherwise reasonably estimated by Landlord,
and all charges in connection therewith shall be payable directly by Tenant.

          (b)  Tenant will pay to Landlord a reasonable charge for any extra
cleaning of the Premises required because of the carelessness or indifference
of Tenant or because of the nature of Tenant's business, or furnished by
Landlord at Tenant's request.  Landlord will endeavor to furnish such requested
extra cleaning service upon reasonable advance written notice from Tenant of its
requirements in that regard.

                                       11
<PAGE>
 
     7.5 Repairs and Other Services.  Except as otherwise provided in
         --------------------------                                       
Articles 16 and 18, and subject to Tenant's obligations in Article 12 and
elsewhere in this Lease, Landlord shall (a) keep and maintain the roof, exterior
walls, structural floor slabs and columns, windows (exclusive of glass
components), and common areas of the Building in as good condition and repair as
they are in on the Term Commencement Date, reasonable use and wear excepted, (b)
keep and maintain in workable condition the Building's sanitary, electrical,
heating, air conditioning and other systems, (c) provide cleaning services to
the Demised Premises and the common areas of the Building on Business Days
according to the cleaning specifications set forth in Exhibit E attached hereto
                                                      ---------                
and made a part hereof, (d) provide maintenance and snow removal for all
roadways, walkways and parking areas on the Property, (e) provide grounds
maintenance to all landscaped areas, and (f) employ a uniformed guard to be
stationed at the main entrance of the Building on an around-the-clock basis.
All expenses incurred by Landlord in connection with the foregoing repairs and
other services shall be included as part of operating expenses pursuant to
Section 6.3.

     7.6 Interruption or Curtailment of Services.  Landlord reserves the
         ---------------------------------------                              
right to interrupt, curtail, stop or suspend the furnishing of services and the
operation of any Building system, when necessary by reason of accident or
emergency, or of repairs, alterations, replacements or improvements in the
reasonable judgment of Landlord desirable or necessary to be made, or of
difficulty or inability in securing supplies or labor, or of strikes, or of any
other cause beyond the reasonable control of Landlord, whether such other cause
be similar or dissimilar to those hereinabove specifically mentioned, until said
cause has been removed, provided, however, that Landlord shall not interrupt
service to the dedicated electric riser referenced in Section 2.2 without
Tenant's prior consent, except in the event of casualty or an emergency.
Landlord shall have no responsibility or liability for any such interruption,
curtailment, stoppage, or suspension of services or systems, except that
Landlord shall exercise reasonable diligence to minimize inconvenience to Tenant
and to eliminate the cause of same and except that Landlord shall give
reasonable notice of such interruption, curtailment, stoppage or suspension
except when due to accident or emergency.

8.   CHANGES OR ALTERATIONS BY LANDLORD

     Landlord reserves the right, exercisable by itself or its nominee, at any
time and from time to time without the same constituting an actual or
constructive eviction and without incurring any liability to Tenant therefor or
otherwise affecting Tenant's obligations under this Lease, to make such changes,
alterations, additions, improvements, repairs or replacements in or to the
Building (including the Demised Premises) and the fixtures and equipment
thereof, as well as in or to the street entrances, halls, passages, elevators,
and stairways thereof, as it may deem necessary or desirable, and to change the
arrangement and/or location of entrances or passageways, doors and doorways, and
corridors, elevators, stairs, toilets, or other public parts of the Building,
provided, however, that there be no unreasonable obstruction of the right of
access to, or unreasonable interference with the use and enjoyment of, the
Demised Premises by Tenant, except that Landlord shall not be obligated to
employ labor at so-called "overtime" or other premium pay rates.  Nothing
contained in this Article shall be deemed to relieve Tenant of any duty,
obligation or liability of Tenant with respect to making or causing to be made
any repair, replacement or

                                       12
<PAGE>
 
improvement or complying with any law, order or requirement of any governmental
or other authority. Landlord reserves the right to from time to time change the
address of the Building. Neither this Lease nor any use by Tenant shall give
Tenant any right or easement or the use of any door or any passage or any
concourse connecting with any other building or to any public convenience, and
the use of such doors, passages and concourses and of such conveniences may be
regulated or discontinued at any time and from time to time by Landlord and
without affecting the obligation of Tenant hereunder or incurring any liability
to Tenant therefor.

9.   FIXTURES, EQUIPMENT AND IMPROVEMENTS - REMOVAL BY TENANT

     All fixtures, equipment, improvements and appurtenances "built into the
Demised Premises" prior to or during the Term, whether by Landlord at its
expense or at the expense of Tenant (either or both) or by Tenant shall be and
remain part of the Demised Premises and shall not be removed by Tenant at the
end of the Term unless otherwise expressly provided in this Lease.  For purposes
of this Lease, "built into the Demised Premises" shall mean that the applicable
fixtures, equipment, improvements and appurtenances are incorporated into the
Demised Premises to such a degree that the removal of the applicable item would
adversely affect the structure of the Demised Premises.  For all fixtures,
equipment, improvements and appurtenances that are installed in the Demised
Premises by Tenant, but are not "built into the Demised Premises", including,
but not limited to, all removable electric fixtures, signs, furniture, or trade
fixtures or business equipment, such items may be removed by Tenant upon the
condition that Tenant shall repair any damage to the Demised Premises or the
Building arising from such removal.

10.  ALTERATIONS AND IMPROVEMENTS BY TENANT; RESTORATION TO SHELL CONDITION

     (a) Tenant shall make no alterations, installations, removals, additions or
improvements in or to the Demised Premises without Landlord's prior written
consent and then only by contractors or mechanics approved by Landlord.  No
installations or other such work shall be undertaken or begun by Tenant until
Landlord has approved written plans and specifications therefor; and no
amendments or additions to such plans and specifications shall be made without
prior written consent of Landlord, which consent shall not be unreasonably
withheld or delayed. Any such work, alterations, decorations, installations,
removals, additions and improvements shall be done at the sole expense of Tenant
and at such times and in such manner as Landlord may from time to time
reasonably designate.

     (b) Landlord, at Landlord's option, by written notice thereof to Tenant
given at any time prior to the date which is sixty (60) days prior to the
Termination Date, may require Tenant, at Tenant's sole and expense, to restore
the Demised Premises to "shell condition", which may include, but shall not
limited to, removal of all data wiring, electric wiring, liebert units, the
halon system, the raised computer floor (to the extent located in the Demised
Premises), and removal of all batteries and equipment from the battery room.

                                       13
<PAGE>
 
11.  TENANT'S CONTRACTORS - MECHANICS' AND OTHER LIENS - STANDARD OF TENANT'S
     PERFORMANCE - COMPLIANCE WITH LAWS

     Whenever Tenant shall make any alterations, decoration, installations,
removals, additions or improvements or do any other work in or to the Demised
Premises, Tenant will strictly observe the following covenants and agreements:

          (a) In no event shall any material or equipment be incorporated in or
added to the Demised Premises in connection with any such alteration,
decoration, installation, addition or improvement which shall cause the Demised
Premises to be subject to any lien, charge, mortgage or other encumbrance of any
kind whatsoever.  Any mechanic's lien filed against the Demised Premises or the
Building for work claimed to have been done for, or materials claimed to have
been furnished to Tenant shall be discharged by Tenant within thirty (30) days
thereafter, at the expense of Tenant, by filing the bond required by law or
otherwise.  If Tenant fails so to discharge any lien, Landlord may do so at
Tenant's expense and Tenant shall reimburse Landlord for any expense or cost
incurred by Landlord in so doing within fifteen (15) days after rendition of a
bill therefor.

          (b) All installations or work done by Tenant under this or any other
Article of this Lease shall be at its own expense (unless expressly otherwise
provided) and shall at all times comply with (i) laws, rules, orders and
regulations of governmental authorities having jurisdiction thereof; (ii)
orders, rules and regulations of any Board of Fire Underwriters, or any other
body hereafter constituted exercising similar functions, and governing insurance
rating bureaus; (iii) plans and specifications prepared by and at the expense of
Tenant theretofore submitted to Landlord for its prior written approval.

          (c) Tenant shall procure all necessary permits before undertaking any
work in the Demised Premises; do all such work in a good and workmanlike manner,
employing materials of good quality and complying with all governmental
requirements and defend, save harmless, exonerate and indemnify Landlord from
all injury, loss or damage to any person or property occasioned by or growing
out of such work.

12.  REPAIRS AND SECURITY BY TENANT

     Tenant shall keep or cause to be kept all and singular the interior, non-
structural portions of the Demised Premises neat and clean and in such repair,
order and condition as the same are in on the Term Commencement Date or may be
put in during the term hereof, reasonable use and wear thereof, damage by fire
or by other insured casualty and repairs required to be made hereunder by
Landlord excepted.

     Tenant shall make, as and when needed as a result of misuse by, or neglect
or improper conduct (including without limitation the placement of any weight
exceeding the floor load) of Tenant or Tenant's servants, employees, agents,
invitees or licensees or otherwise, all repairs in

                                       14
<PAGE>
 
and about the interior, non-structural portions of the Demised Premises
necessary to preserve them in such repair, order and condition, which repairs
shall be in quality and class equal to the original work. Landlord may elect, at
the expense of Tenant, either pursuant to Section 15.3 or otherwise, to make any
such repairs or to repair any damage or injury to the Building or the Demised
Premises caused by moving property of Tenant in or out of the Building, or by
installation or removal of furniture or other property, or by misuse by, or
neglect or improper conduct of, Tenant or Tenant's servants, employees, agents
or licensees.

13.  INSURANCE, INDEMNIFICATION, EXONERATION AND EXCULPATION

     13.1 Insurance.  Tenant shall procure, keep in force and pay for (a)
          ---------                                                       
Comprehensive Public Liability Insurance indemnifying Landlord, any managing
agent designated by Landlord, Tenant and (whenever Landlord shall so request)
any Mortgagee against all claims and demands for injury to or death of persons
or damage to property which may be claimed to have occurred upon the Demised
Premises in the amounts which shall at the time Tenant and/or contractors enter
the Premises in accordance with Article 4 of this Lease be not less than Two
Hundred Thousand Dollars ($200,000) for property damage, One Million Dollars
($1,000,000) for injury or death of one person, and Two Million Dollars
($2,000,000) for injury or death of more than one person in a single accident,
and from time to time thereafter shall be not less than such higher amounts, if
procurable, as may be reasonably required by Landlord and are customarily
carried by responsible office tenants in the Greater Boston area, (b) insurance
covering any damage to the plate glass windows in or immediately about the
Demised Premises, in reasonable amounts to be established from time to time by
Landlord, and (c) so-called contents and improvements insurance adequately
insuring all property belonging to or removable by Tenant and situated in the
Demised Premises.

     13.2 Certificates of Insurance.  Such insurance shall be effected with
          -------------------------                                            
insurers authorized to do business in Massachusetts under valid and enforceable
policies, and such policies shall name Landlord, each Mortgagee, Tenant and any
additional parties designated by Landlord pursuant to Section 13.1 as the
insureds, as their respective interests appear.  Such insurance shall provide
that it shall not be cancelled without at least ten (10) days' prior written
notice to each insured named therein.  On or before the Term Commencement Date
and thereafter not less than fifteen (15) days prior to the expiration date of
each expiring policy, certificates of the policies provided for in Section 13.1
issued by the respective insurers, setting forth in full the provisions thereof
and issued by such insurers together with evidence satisfactory to Landlord of
the payment of all premiums for such policies, shall be delivered by Tenant to
Landlord and certificates as aforesaid of such policies shall, upon request of
Landlord, be delivered by Tenant to the holder of any mortgage affecting the
Demised Premises.

     13.3 General.  Tenant will save Landlord harmless, and will exonerate and
          -------                                                               
indemnify Landlord, from and against any and all claims, liabilities or
penalties asserted by or on behalf of any person, firm, corporation or public
authority:

          (a) On account of or based upon any injury to person, or loss of or
damage to property sustained or occurring on the Demised Premises on account of
or based upon the act,

                                       15
<PAGE>
 
omission, fault, negligence or misconduct of any person whomsoever (other than
as a consequence of the negligence or wilful misconduct of Landlord or its
agents or employees);

          (b) On account of or based upon any injury to person or loss of or
damage to property, sustained or occurring elsewhere (other than on the Demised
Premises) in or about the Building (and, in particular, without limiting the
generality of the foregoing on or about the elevators, stairways, public
corridors, sidewalks, concourses, arcades, malls, galleries, vehicular tunnels,
approaches, areaways, roof, or other appurtenances and facilities used in
connection with the Building or Demised Premises) arising out of the use or
occupancy of the Building or Demised Premises by the Tenant, or any person
claiming by, through or under Tenant;

          (c) On account of or based upon (including monies due on account of)
any work or thing whatsoever done (other than by Landlord or its contractors, or
agents or employees of either) in the Demised Premises during the Term of this
Lease and during the period of time, if any, prior to the Term Commencement Date
that Tenant may have been given access to the Demised Premises; and

          (d) On account of or resulting from the failure of Tenant to perform
and discharge any of its covenants and obligations under this Lease;

and, in respect of any of the foregoing items (a) - (d), from and against all
costs, expenses (including reasonable attorneys' fees), and liabilities incurred
in or in connection with any such claim, or any action or proceeding brought
thereon; and in case any action or proceeding be brought against Landlord by
reason of any such claim, Tenant upon notice from Landlord shall at Tenant's
expense resist or defend such action or proceeding and employ counsel therefor
reasonably satisfactory to Landlord, it being agreed that such counsel as may
act for insurance underwriters of Tenant engaged in such defense shall be deemed
satisfactory.

     13.4 Property of Tenant.  In addition to and not in limitation of the
          ------------------                                                  
foregoing, Tenant covenants and agrees that all merchandise, furniture, fixtures
and property of every kind, nature and description which may be in or upon the
Demised Premises or Building, in the public corridors, or on the sidewalks,
areaways and approaches adjacent thereto, during the term hereof, shall be at
the sole risk and hazard of Tenant, and that if the whole or any part thereof
shall be damaged, destroyed, stolen or removed from any cause or reason
whatsoever no part of said damage or loss shall be charged to, or borne by
Landlord.

     13.5 Bursting of Pipes, etc.  Landlord shall not be liable for any injury
          ----------------------                                                
or damage to persons or property resulting from fire, explosion, falling
plaster, steam, gas, electricity, electrical disturbance, water, rain or snow or
leaks from any part of the Building or from the pipes, appliances or plumbing
works or from the roof, street or sub-surface or from any other place or caused
by dampness or by any other cause of whatever nature, unless caused by or due to
the negligence of Landlord, its agents, servants or employees, and then only
after (i) notice to Landlord of the condition claimed to constitute negligence
an (ii) the expiration of a reasonable time after such notice has been received
by Landlord without such condition having been cured or

                                       16
<PAGE>
 
corrected; and in no event shall Landlord be liable for any loss, the risk of
which is compensated by Tenant's insurance; nor shall Landlord or its agents be
liable for any such damage caused by other tenants or persons in the Building or
caused by operations in construction of any private, public or quasi-public
work.

     13.6 Repairs and Alterations - No Diminution of Rental Value. Except as
          -------------------------------------------------------
otherwise provided in Articles 16 or 18, there shall be no allowance to Tenant
for diminution of rental value and no liability on the part of Landlord by
reason of inconvenience, annoyance or injury to Tenant arising from any repairs,
alterations, additions, replacements or improvements made by Landlord, Tenant or
others in or to any portion of the Building or Demised Premises, or in or to
fixtures, appurtenances, or equipment thereof, or for failure of Landlord or
others to make any repairs, alterations, additions or improvements in or to any
portion of the Building or of the Demised Premises, or in or to the fixtures,
appurtenances or equipment thereof provided, however, that any such work
performed by or on behalf of Landlord shall be subject to the provisions of
Section 15.2.

14.  ASSIGNMENT, MORTGAGING, SUBLETTING, ETC.

     14.1 Restrictions.  Tenant covenants and agrees that neither this Lease
          ------------                                                        
nor the term and estate hereby granted nor any interest herein or therein, will
be assigned, sublet, mortgaged, pledged, encumbered or otherwise transferred
(whether voluntarily or by operation of law) and that neither the Demised
Premises, nor any part thereof, will be encumbered in any manner by reason of
any act or omission on the part of Tenant, or used or occupied, or permitted to
be used or occupied, or utilized for any reason whatsoever, by anyone other than
Tenant, or for any use or purpose other than a stated in Article 1 without the
prior written consent of Landlord in every case.

     14.2 Requests to Assign or Sublet.  In connection with any request by
          ----------------------------                                      
Tenant for such consent to assign or sublet, Tenant shall submit to Landlord, in
writing, a statement containing the name of the proposed assignee or subtenant,
such information as to its financial responsibility and standing as Landlord may
reasonably require, and all of the terms and provisions upon which the proposed
assignment or subletting is to be made, and, unless the proposed area to be
assigned or sublet shall constitute an entire floor or floors, such statement
shall be accompanied by a floor plan delineating the proposed area to be
assigned or sublet.  In no event shall Tenant sublet the Demised Premises for a
rent which is less than the then fair market rent for new leases in the Building
as determined by Landlord in its sole reasonable discretion.  As long as Tenant
is not in default under any of the terms, covenants and conditions of this Lease
on Tenant's part to be observed and performed, Landlord shall not unreasonably
withhold or delay Landlord's prior consent to the assignment or subletting(s) by
Tenant of all or parts of the Demised Premises.  Each such subletting be for
undivided occupancy by the subtenant of that part of the Demised Premises
affected thereby for the use permitted under this Lease and at no time shall
there be more than three (3) occupants, including Tenant, within the Demised
Premises.  Landlord may, however, withhold such consent if, in Landlord's
reasonable judgment, the proposed assignee or subtenant is not engaged in a
business consistent with the character and dignity of the Building, or will
impose

                                       17
<PAGE>
 
any additional material burden upon Landlord in the operation of the Building
(to an extent greater than the burden to which Landlord would have been put if
Tenant continued to use, or used, such part of the Demised Premises for its own
purposes), or if Landlord has any other reasonable objections to the proposed
assignment or subletting. Any Colocation shall not be deemed an assignment or
subletting.

     14.3 Exceptions.  Notwithstanding the foregoing, Tenant may, without the
          ----------                                                           
requirement of obtaining Landlord's consent, assign this Lease or sublease any
portion of the Demised Premises to any entity which is (i) the parent, a
majority-owned subsidiary of Tenant, (ii) an entity under common control with
Tenant, (iii) an entity with which Tenant may merge or consolidate or to which
Tenant may sell all or substantially all of its assets as a going concern (such
entity with which Tenant may merge, consolidate or to which Tenant may sell all
or substantially all of its assets as aforesaid being hereinafter referred to as
a "Successor"), and (iv) an entity having a net worth in excess of $20,000,000
at the time of such assignment or subletting (an "Unrelated Transferee"),
provided that, simultaneously with any such assignment, Tenant shall deliver to
Landlord an agreement in form and substance reasonably satisfactory to Landlord
which contains an appropriate covenant of assumption by such assignee; and
provided further that in the case of any such assignment or sublease to a
Successor, Tenant shall have submitted to Landlord prior thereto financial
statements or other materials reasonably satisfactory to Landlord evidencing
that such Successor has financial resources comparable to that of Tenant as of
the time of such assignment or sublease.  In addition, in the case of an
assignment or subletting to an Unrelated Transferee, Tenant shall have submitted
to Landlord prior thereto financial statements or other materials reasonably
satisfactory to Landlord evidencing that such Unrelated Transferee has a net
worth in excess of $20,000,000 at the time of such assignment or subletting.

     14.4 Excess Rent.  Except for subleases or assignments pursuant to
          -----------                                                    
Section 14.3, if the rent received by Tenant on account of a sublease of all or
any portion of the Demised Premises exceeds the Yearly Fixed Rent and Additional
Rent, allocated to the space subject to the sublease in the proportion of the
area of such space to the area of the entire Demised Premises, Tenant shall pay
to Landlord such excess, monthly as received by Tenant.

     14.5 Recapture.  Notwithstanding the foregoing provisions of this Article
          ---------                                                            
and except in the cases of subleases or assignments pursuant to Section 14.3:
(1) in the event Tenant proposes to assign or sublet all of the Demised
Premises, Landlord, at Landlord's option, may give to Tenant, within ten (10)
business days after the submission by Tenant to Landlord of the statement
required to be submitted in connection with such assignment or subletting, or,
if Tenant so requests, within ten (10) business days after Tenant notifies
Landlord that Tenant wishes to undertake such assignment or subletting, but has
not yet procured a proposed assignee or subtenant, a notice terminating this
Lease on the date (referred to as the "Earlier Termination Date") immediately
prior to the proposed commencement date of the term of the proposed assignment
or subletting, as set forth in such statement, and, in the event such notice is
given, this Lease and the Term shall come to an end and expire on the Earlier
Termination Date with the same effect as if it were the date originally fixed in
this Lease for the end of the Term of this Lease, and the Rent shall be
apportioned as of said Earlier Termination Date and any prepaid portion of Rent
for any period

                                       18
<PAGE>
 
after such date shall be refunded by Landlord to Tenant, provided, however, that
in the event Landlord shall so elect to terminate this Lease, Tenant, upon
written notice to Landlord given within ten (10) days of receipt by Tenant of
Landlord's notice of termination, may elect to negate such termination by
declaring its intent not to proceed with such assignment or subletting; or (2)
in the event Tenant proposes to assign or sublet in the aggregate in excess of
fifty percent (50%) of the original square footage of the Demised Premises,
Landlord, at Landlord's option, may give to Tenant, within thirty (30) days
after the submission by Tenant to Landlord of the statement required to be
submitted in connection with such proposed assignment or subletting, a notice
electing to eliminate such portion of the Demised Premises (said portion is
referred to as the "Eliminated Space") from the Demised Premises during the
period (referred to as the "Elimination Period") commencing on the date
(referred to as the "Elimination Date") immediately prior to the proposed
commencement date of the term of the proposed assignment or subletting, as set
forth in such statement, and ending on the proposed expiration date of the term
of the proposed assignment or subletting, as set forth in such statement, and in
the event such notice is given (i) the Eliminated Space shall be eliminated from
the Demised Premises during the Elimination Period; (ii) Tenant shall surrender
the Eliminated Space to Landlord on or prior to the Elimination Date in the same
manner as if said Date were the date originally fixed in this Lease for the end
of the Term of this Lease; (iii) if the Eliminated Space shall constitute less
than an entire floor, Landlord, at Landlord's expense, shall have the right to
make any alterations and installations in the Demised Premises required, in
Landlord's judgment, reasonably exercised, to make the Eliminated Space a self-
contained rental unit with access through corridors to the elevators and core
toilets serving the Eliminated Space, and if the Demised Premises shall contain
any core toilets or any corridors (including any corridors proposed to be
constructed by Landlord pursuant to this subdivision (iii) providing access from
the Eliminated Space to the core area), Landlord and any tenant or other
occupant of the Eliminated Space shall have the right to use such toilets and
corridors in common with Tenant and any other permitted occupants of the Demised
Premises, and the right to install signs and directional indicators in or about
such corridors indicating the name and location of such tenant or other
occupant; (iv) during the Elimination Period, the Yearly Fixed Rent shall be
reduced in the proportion which the area of the Eliminated Space bears to the
total area of the Demised Premises immediately prior to the Elimination Date
(including an equitable portion of the area of any corridors referred to in
subdivision (iii) of this sentence as part of the area of the Eliminated Space
for the purpose of computing such reduction), and any prepaid Rent for any
period after the Elimination Date allocable to the Eliminated Space shall be
refunded by Landlord to Tenant; (v) there shall be an equitable apportionment of
any Additional Rent Payable pursuant to Article 6 for the relevant fiscal and
calendar years in which said Elimination Date shall occur; and (vi) if the
Elimination Period shall end prior to the date originally fixed in this Lease
for the end of the Term of this Lease, the Eliminated Space, in its then
existing condition, shall be deemed restored to and once again a part of the
Demised Premises subject to the provisions of this Lease as if said elimination
had not occurred during the period (referred to as the "Restoration Period")
commencing on the date next following the expiration of the Elimination Period
and ending on the date originally fixed in this Lease for the end of the Term of
this Lease, except in the event that Landlord is unable to give Tenant
possession of the Eliminated Space at the expiration of the Elimination Period
by reason of the holding over or retention of possession of any tenant or other
occupant, in which event (x) the Restoration Period shall not commence, and 

                                       19
<PAGE>
 
the Eliminated Space shall not be deemed restored to or a part of the Demised
Premises, until the date upon which Landlord shall give Tenant possession of
such Space free of occupancies, provided Landlord shall use reasonable efforts
to return the Eliminated Space to Tenant at the expiration of the Elimination
Period, (y) neither the date fixed in this Lease for the end of the Term of the
Lease, nor the validity of this Lease shall be affected and (z) Tenant waives
any right to recover any damages which may result from the failure of Landlord
to deliver possession of the Eliminated Space at the end of the Elimination
Period excepting only those resulting from Landlord's gross negligence or
willful misconduct.

     14.6 Further Documentation.  At the request of Landlord, Tenant shall
          ---------------------                                             
execute and deliver an instrument or instruments, in form satisfactory to
Landlord, setting forth any modifications to this Lease contemplated in or
resulting from the operation of the foregoing provisions of this paragraph;
however, neither Landlord's failure to request any such instrument nor Tenant's
failure to execute or deliver any such instrument shall vitiate the effect of
the foregoing provisions of this Article.

     14.7 General.
          -------   

          (a)  The failure by Landlord to exercise its option under this
paragraph with respect to any subletting shall not be deemed a waiver of such
option with respect to any extension or any subsequent subletting of the
premises affected thereby.  Tenant shall reimburse Landlord promptly, as
Additional Rent, for reasonable legal and other expense incurred by Landlord in
connection with any request by Tenant for any consent required under the
provisions of this Article.

          (b)  Except for Colocation and except as set forth in Section 14.7(e)
below, it is specifically understood and agreed that neither Tenant nor any
other person having an interest in the possession, use, occupancy or utilization
of the Demised Premises shall enter into any sublease, license, concession or
other agreement (or renewals of any of the foregoing) for use, occupancy or
utilization of space in the Demised Premises which provides for rental or other
payment for such use, occupancy or utilization based, in whole or in part, on
the net income or profits derived by any person or entity from the space leased,
used, occupied or utilized (other than an amount based on a fixed percentage or
percentages of receipts or sales).  Any such purported sublease or other
agreement shall be absolutely void and ineffective as a conveyance of any right
or interest in the possession, use, occupancy, or utilization of any part of the
Demised Premises.

                                       20
<PAGE>
 
          (c)  The listing of any name other than that of Tenant, whether on the
doors of the Demised Premises or on the Building directory, or otherwise, shall
not operate to vest any right or interest in this Lease or in the Demised
Premises or be deemed to  be the written consent of Landlord mentioned in this
Article, it being expressly understood that any such listing is a privilege
extended by Landlord revocable at will by written notice to Tenant.

          (d)  If this Lease be assigned, or if the Demised Premises or any part
thereof shall be sublet or occupied by anybody other than Tenant, Landlord may
at any time and from time to time, collect rent and other charges from the
assignee, subtenant or occupant and apply the aggregate amount collected to the
Rent and other charges herein reserved, but no such assignment or collection
shall be deemed a waiver of this covenant, or the acceptance of the assignee,
subtenant or occupant as a tenant, or a release of Tenant from the further
performance by Tenant of covenants on the part of Tenant herein contained.
Landlord shall notify Tenant of any amounts so collected by Landlord directly
from such subtenant or assignee.  The consent by Landlord to an assignment or
subletting or occupancy shall not in any way be construed to relieve Tenant from
obtaining the express consent in writing of Landlord to any further assignment
or subletting or occupancy.

          (e)  Landlord acknowledges that Tenant has agreed to permit the
preceding tenant of the Demised Premises, XCOM Technologies, Inc. ("XCOM"), to
continue to operate and maintain certain telecommunications equipment in the
Demised Premises (and such other Telecommunications Equipment and Cabling that
currently exists in the Building and was heretofore used by such XCOM) after the
Commencement Date in order to permit said tenant a sufficient period of time to
relocate itself to a new location outside the Building.  Landlord agrees that
such use shall not be deemed an assignment or subletting.  Tenant agrees that
Landlord shall not be liable in any manner to Tenant or any other party as a
consequence of such arrangement between Tenant and XCOM and that such
arrangement shall in no manner constitute a breach or give rise to any claims
under Article 22 hereof and/or any other provision of this Lease.

15.  MISCELLANEOUS COVENANTS

     15.1 Rules and Regulations. Tenant and Tenant's servants, employees, and
          ---------------------
agents will faithfully observe such Rules and Regulations as are attached hereto
as Exhibit F and made a part hereof or as Landlord hereafter at any time or from
   ---------
time to time may make and may communicate in writing to Tenant and which in the
reasonable judgment of Landlord shall be necessary for the reputation, safety,
care or appearance of the Property, or the preservation of good order therein,
or the operation or maintenance of the Property, or the equipment thereof, or
the comfort of tenants or others in the Building, provided, however, that in the
case of any conflict between the provisions of this Lease and any such Rules and
Regulations, the provisions of this Lease shall control, and provided further
that nothing contained in this Lease shall be construed to impose upon Landlord
any duty or obligation to enforce such Rules and Regulations or the terms,
covenants or conditions in any other lease as against any other tenant and
Landlord shall not be liable to Tenant for violation of the same by any other
tenant, its servants, employees, agents, visitors, invitees or licensees.

                                       21
<PAGE>
 
     15.2 Access to Premises - Shoring.  Tenant shall:  (i) permit Landlord to
          ----------------------------                                          
erect, use and maintain pipes, ducts and conduits in and through the Demised
Premises, provided the same do not materially reduce the floor area or
materially adversely affect the appearance thereof; (ii) permit the Landlord and
any Mortgagee of the Building or the Building and Land or of the interest of
Landlord therein, and any lessor under any ground or underlying lease, and their
representatives, to have free and unrestricted access to and to enter upon the
Demised Premises at all reasonable hours for the purposes of inspection or of
making  repairs, replacements or improvements in or to the Demised Premises or
the Building or equipment (including, without limitation, sanitary, electrical,
heating, air conditioning or other systems) or of complying with all laws,
orders and requirements of governmental or other authority or of exercising any
right reserved to Landlord by this Lease (including the right during the
progress of any such repairs, replacements or improvements or while performing
work and furnishing materials in connection with compliance with any such laws,
orders or requirements to take upon or through, or to keep and store within, the
Demised Premises all necessary materials, tools and equipment); and (iii) permit
Landlord, at reasonable times, to show the Demised Premises during ordinary
business hours to any Mortgagee, ground lessor, prospective purchaser,
prospective mortgagee, or prospective assignee of any mortgage, of the Building
or of the Building and the Land or of the interest of Landlord therein, and
during the period of twelve months next preceding the Termination Date to any
person contemplating the leasing of the Demised Premises or any part thereof.
If during the last month of the Term, Tenant shall have removed all of Tenant's
property therefrom, Landlord may immediately enter and alter, renovate and
redecorate the Demised Premises, without elimination or abatement of rent, or
incurring liability to Tenant for any compensation, and such acts shall have no
effect upon this Lease.  If Tenant shall not be personally present to open and
permit any entry into the Demised Premises at any time when for any reason an
entry therein shall be necessary or permissible, Landlord or Landlord's agents
must nevertheless be able to gain such entry by contacting a responsible
representative of Tenant, whose name, address and telephone number shall be
furnished by Tenant.  Provided that Landlord shall incur no additional expense
thereby, Landlord shall exercise its rights of access to the Demised Premises
permitted under any of the terms and provisions of this Lease in such manner as
to minimize to the extent practicable interference with Tenant's use and
occupation of the Demised Premises, and upon reasonable prior notice, except in
the case of an emergency or where such notice is not reasonably practical.  If
an excavation shall be made upon land adjacent to the Demised Premises or shall
be authorized to be made, Tenant shall afford, to the causing or authorized to
cause such excavation, license to enter upon the Demised Premises for the
purpose of doing such work as said person shall deem necessary to preserve the
Building from injury or damage and to support the same by proper foundations
without any claim for damage or indemnity against Landlord, or diminution or
abatement of Rent.

     15.3 Accidents to Sanitary and Other Systems.  Tenant shall give to
          ---------------------------------------                              
Landlord prompt notice of any fire or accident in the Demised Premises or in the
Building and of any damage to, or defective condition in, any part or
appurtenance of the Building's sanitary, electrical, heating and air
conditioning or other systems located in, or passing through, the Demised
Premises, and the damage or defective condition shall be remedied  by Landlord
with reasonable diligence, but if 

                                       22
<PAGE>
 
such damage or defective condition was caused by Tenant or by the employees,
licensees, or invitees of Tenant, the cost to remedy the same shall be paid by
Tenant. Tenant shall not be entitled to claim any eviction from the Demised
Premises or any damages arising from any such damage or defect unless the same
(i) shall have been occasioned by the negligence of Landlord, its agents,
servants or employees and (ii) shall not, after notice to Landlord of the
condition claimed to constitute negligence, have been cured or corrected within
a reasonable time after such notice has been received by Landlord; and in case
of a claim of eviction unless such damage or defective condition shall have
rendered the Demised Premises untenantable and they shall not have been made
tenantable by Landlord within a reasonable time. Landlord agrees to diligently
work to correct such damage or defect, except as otherwise provided herein.

     15.4 Signs, Blinds and Drapes. Tenant shall not place any signs on the
          ------------------------
exterior of the Building or on or in any window, public corridor or door visible
from the exterior of the Demised Premises. No blinds may be put on or in any
window nor may any Building drapes or blinds be removed by Tenant. Tenant may
hang its own drapes, provided that they shall not, without the prior written
approval of Landlord, in any way interfere with any Building drapery or blinds
or be visible from the exterior of the Building.

     15.5 Estoppel Certificate. Either party shall at any time and from time to
          --------------------
time upon not less than twenty (20) days' prior notice by Landlord to Tenant or
by a Mortgagee to Tenant, or by Tenant to Landlord, as the case may be, execute,
acknowledge and deliver to the party making such request a statement in writing
certifying that this Lease is unmodified and in full force and effect (or if
there have been modifications, that the same is in full force and effect as
modified and stating the modifications) and the dates to which Rent has been
paid in advance, if any, an stating whether or not to the best knowledge of the
signer of such certificate Landlord is in default in performance of any
covenant, agreement, term, provisions or condition contained in this Lease and,
if so, specifying each such default of which the signer may have knowledge, it
being intended that any such statement delivered pursuant hereto may be relied
upon by any prospective purchaser of the Building or of the Building and the
Land or of the interest of Landlord therein, any Mortgagee or prospective
Mortgagee thereof, any lessor or prospective lessor thereof, any lessee or
prospective lessee thereof, or any prospective assignee of any Mortgage. The
form of any such estoppel certificate requested by a Mortgagee shall be
satisfactory to such Mortgagee. Notwithstanding anything contained in this Lease
to the contrary, the provisions of this Section 15.5 shall be inapplicable to
Teachers Insurance and Annuity Association in the event said entity shall
succeed to the rights of Landlord hereunder.

     15.6 Prohibited Items. Tenant shall not bring or permit to be brought or
          ----------------
kept in or on the Demised Premises or elsewhere in the Building any hazardous,
inflammable, combustible or explosive fluid, material, chemical or substance
(except such as are related to Tenant's use of the Demised Premises, provided
that the same are stored and handled in a proper fashion consistent with all
applicable legal standards).


     15.7 Requirements of Law; Fines and Penalties. Tenant at its sole expense
          ----------------------------------------
shall comply 

                                       23
<PAGE>
 
with all laws, rules, orders and regulations of Federal, State, County and
Municipal Authorities and with any direction of any public officer or officers,
pursuant to law, which shall impose any duty upon Landlord or Tenant with
respect to and arising out of Tenant's use or occupancy of the Demised Premises.
Tenant shall reimburse and compensate Landlord for all expenditures made by, or
damages or fines sustained or incurred by, Landlord due to nonperformance or
noncompliance with or breach or failure to observe any term, covenant or
condition of this Lease upon Tenant's part to be kept, observed, performed or
complied with. If Tenant receives notice of any violation of law, ordinance,
order or regulation applicable to the Demised Premises, it shall give prompt
notice thereof to Landlord.

     15.8 Tenant's Acts - Effect on Insurance. Except for permitted uses, Tenant
          -----------------------------------
shall not do or permit to be done any act or thing upon the Demised Premises or
elsewhere in the Building which will invalidate or be in conflict with any
insurance policies covering the Building and the fixtures and property therein
and shall not do, or permit to be done, any act or thing upon the Demised
Premises which shall subject Landlord to any liability or responsibility for
injury to any person or persons or to property by reason of any business or
operation being conducted on said Demised Premises or for any other reason.
Tenant at its own expense shall comply with all rules, orders, regulations or
requirements of the Board of Fire Underwriters or any other similar body having
jurisdiction, and shall not (i) do, or permit anything to be done, in or upon
the Demised Premises, or bring or keep anything therein, except as now or
hereafter permitted by the Fire Department, Board of Underwriters, Fire
Insurance Rating Organization, or other authority having jurisdiction, and then
only in such quantity and manner of storage as will not increase the rate for
any insurance applicable to the Building, or (ii) use the Demised Premises in
manner which shall increase such insurance rates on the Building or on property
located therein, over that applicable when Tenant first took occupancy of the
Demised Premises hereunder. If by reason of failure of Tenant to comply with the
provisions hereof the insurance rate applicable to any policy of insurance shall
at any time thereafter be higher than it otherwise would be, then Tenant shall
reimburse Landlord for that part of any insurance premiums thereafter paid by
Landlord, which shall have been charged because of such failure by Tenant.

     15.9 Hazardous Materials. Tenant shall not (either with or without
          -------------------
negligence) cause or permit the escape, disposal or release of any biologically
or chemically active or other hazardous substances, or materials. Tenant shall
not allow the storage or use of such substances or materials in any manner not
sanctioned by law or by the highest standards prevailing in the industry for the
storage and use of such substances or materials, nor allow to be brought onto
the Property any such materials or substances except to use in the ordinary
course of Tenant's business, and then only after written notice is given to
Landlord of the identity of such substances or materials. Without limitation,
hazardous substances and materials shall include those described in the
Comprehensive Environmental Response, Compensation and Liability Act of 1980, as
amended, 42 U.S.C. Section 9601 et seq., any applicable state or local laws and
the regulations adopted under these acts. If any lender or governmental agency
shall ever require testing to ascertain whether or not there has been any
release of hazardous materials, then the reasonable costs thereof shall be
reimbursed by Tenant to Landlord upon demand as additional charges if such
requirement applies to the Demised Premises. In addition, Tenant shall execute
affidavits, representations and 

                                       24
<PAGE>
 
the like from time to time at Landlord's request concerning Tenant's best
knowledge and belief regarding the presence of hazardous substances or materials
on the Demised Premises. In all events, Tenant shall indemnify Landlord in the
manner elsewhere provided in this Lease from any release of hazardous materials
on the Demised Premises occurring while Tenant is in possession, or elsewhere if
caused by Tenant or persons acting under Tenant. The within covenants shall
survive the expiration or earlier termination of the Term of this Lease.

     15.10 Miscellaneous. Tenant shall not suffer or permit the Demised Premises
           -------------
or any fixtures, equipment or utilities therein or serving the same, to be
overloaded, damaged or defaced, nor permit any hole to be drilled or made in any
part thereof.

16.  DAMAGE BY FIRE, ETC.

     In the event of loss of, or damage to, the Demised Premises or the Building
by fire or other casualty, the rights and obligations of the parties hereto
shall be as follows:

          (a)  If the Demised Premises, or any part thereof, shall be damaged by
fire or other casualty, Tenant shall give prompt notice thereof to Landlord, and
Landlord, upon receiving such notice, shall proceed promptly and with due
diligence, subject to unavoidable delays, to repair, or cause to be repaired,
such damage.  If the Demised Premises or any part thereof shall be rendered
untenantable by reason of such damage, whether to the Demised Premises or to the
Building, the Yearly Fixed Rent and Additional Rent shall proportionately abate
for the period from the date of such damage to the date when such damage shall
have been repaired.

          (b)  If, as a result of fire or other casualty, the whole or a
substantial portion of the Building is rendered untenantable, Landlord, within
ninety (90) days from the date of such fire or other casualty, may terminate
this Lease by notice to Tenant, specifying a date not less than twenty (20) nor
more than forty (40) days after the giving of such notice on which the Term of
this Lease shall terminate.  If Landlord does not so elect to terminate this
Lease, then Landlord shall proceed with diligence to repair the damage to the
Demised Premises and all facilities serving the same, if any, which shall have
occurred, and the Yearly Fixed Rent and Additional Rent shall meanwhile
proportionately abate, all as provided in Paragraph (a) of this Section.
However, if, in the event of any damage by fire or other casualty, such damage
is not repaired and the Demised Premises and all facilities serving the same
restored to substantially the same condition as they were prior to such damage
within six (6) months from the date of such damage, Tenant within thirty (30)
days from the expiration of such six (6) month period, may terminate this Lease
by notice to Landlord, specifying a date not more than sixty (60) days after the
giving of such notice on which the term of this Lease shall terminate.

          (c)  If the Demised Premises shall be rendered untenantable by fire or
other casualty during the last two (2) years of the Term of this Lease, Landlord
may terminate this Lease effective as of the date of such fire or other casualty
upon notice to Tenant given within thirty (30) days after such fire or other
casualty.

                                       25
<PAGE>
 
          (d)  Landlord shall not be required to repair or replace any of
Tenant's business machinery, equipment, cabinet  work, furniture, personal
property or other installations (which shall, however, be substantially restored
by Tenant within ninety (90) days after Landlord shall have completed any repair
or restoration required under the terms of this Article), and no damages,
compensation or claim shall be payable by Landlord for inconvenience, loss of
business or annoyance arising from any repair or restoration of any portion of
the Demised Premises or of the Building.

          (e)  The provisions of this Article shall be considered an express
agreement governing any instance of damage or destruction of the Building or the
Demised Premises by fire or other casualty, and any law now or hereafter in
force providing for such a contingency in the absence of express agreement shall
have no application.

          (f)  In the event of any termination of this Lease pursuant to this
Article, the Term of this Lease shall expire as of the effective termination
date as fully and completely as if such date were the date herein originally
scheduled as the Termination Date.  Tenant shall have access to the Demised
Premises for a period of thirty (30) days after the date of termination in order
to remove Tenant's personal property.

          (g)  Landlord's Architect's certificate, given in good faith, shall be
deemed conclusive of the statements therein contained and binding upon Tenant
with respect to the performance and completion of any repair or restoration work
undertaken by Landlord pursuant to this Article or Article 18.  Any minor or
insubstantial details of construction or mechanical adjustments which remain to
be done after the delivery of said certificate shall be handled on a punch list
basis and thereafter promptly completed by Landlord.

17.  WAIVER OF SUBROGATION

     In any case in which Tenant shall be obligated under any provision of this
Lease to pay to Landlord any loss, cost, damage, liability, or expense suffered
or incurred by Landlord, Landlord shall allow to Tenant as an offset against the
amount thereof the net proceeds of any insurance collected by Landlord for or on
account of such loss, cost, damage, liability or expense, provided that the
allowance of such offset does not invalidate or prejudice the policy or policies
under which such proceeds were payable.

     In any case in which Landlord shall be obligated under any provision of
this Lease to pay to Tenant any loss, cost, damage, liability or expense
suffered or incurred by Tenant, Tenant shall allow to Landlord as an offset
against the amount thereof (i) the net proceeds of any insurance collected by
Tenant for or on account of such loss, cost, damage, liability, or expense,
provided that the allowance of such offset does not invalidate the policy or
policies under which such proceeds were payable and  (ii) if such loss, cost,
damage, liability or expense shall have been caused by a peril against which
Tenant has agreed to procure insurance coverage under the terms of this Lease,
the amount of such insurance coverage, whether or not actually procured by
Tenant.

                                       26
<PAGE>
 
     The parties hereto shall each endeavor to procure an appropriate clause in,
or endorsement on, any fire or extended coverage insurance policy covering the
Demised Premises and the Building and personal property, fixtures and equipment
located thereon or therein, pursuant to which the insurance companies waive
subrogation or consent to a waiver of right of recovery, and having obtained
such clauses and/or endorsements of waiver of subrogation or consent to a waiver
of right of recovery each party hereby agrees that it will not make any claim
against or seek to recover from the other for any loss or damage to its property
or the property of others resulting from fire or other perils covered by such
fire and extended coverage insurance; provided, however, that the release,
discharge, exoneration and covenant not to sue herein contained shall be limited
by the terms and provisions of the waiver of subrogation clauses and/or
endorsements or clauses and/or endorsements consenting to a waiver of right of
recovery and shall be co-extensive therewith.  If either party may obtain such
clause or endorsement only upon payment of an additional premium, such party
shall promptly so advise the other party and shall be under no obligation to
obtain such clause or endorsement unless such other party pays the premium.

18.  CONDEMNATION - EMINENT DOMAIN

     In the event that the whole or any material part of the Building shall be
taken or appropriated by eminent domain or shall be condemned for any public or
quasi-public use, or (by virtue of any such taking, appropriation or
condemnation) shall suffer any damage (direct, indirect or consequential) for
which Landlord or Tenant shall be entitled to compensation then (and in any such
event) this Lease and the Term hereof may be terminated at the election of
Landlord by a notice in writing of its election so to terminate which shall be
given by the Landlord to Tenant within sixty (60) days following the date on
which Landlord shall have received notice of such taking, appropriation or
condemnation.  In the event that more than twenty-five percent (25%) of the
floor area of the Demised Premises shall be so taken, appropriated or condemned,
then (and in any such event) this Lease and the Term hereof may be terminated at
the election of Tenant by a notice in writing of its election so to terminate
which shall be given by Tenant to Landlord within sixty (60) days following the
date on which Tenant shall have received notice of such taking, appropriation or
condemnation.

     Upon the giving of any such notice of termination (either by Landlord or
Tenant) this Lease and the Term hereof shall terminate on or retroactively as of
the date on which Tenant  shall be required to vacate any part of the Demised
Premises or shall be deprived of a substantial part of the means of access
thereto, provided, however, that Landlord may in Landlord's notice elect to
terminate this Lease and the Term hereof retroactively as of the date on which
such taking, appropriation or condemnation became legally effective.  In the
event of any such termination, this Lease and the Term hereof shall expire as of
the effective termination date as fully and completely as if such date were the
date herein originally scheduled as the Termination Date.  If neither party
(having the right so to do) elects to terminate Landlord will, with reasonable
diligence and at Landlord's expense, restore the remainder of the Demised
Premises, or the remainder of the means of access, as nearly as practicably may
be to the same condition as obtained prior to such taking, appropriation or
condemnation in which event (i) a just proportion of the Yearly Fixed Rent and
Additional Rent, according to the nature and extent of the taking, appropriation
or 

                                       27
<PAGE>
 
condemnation and the resulting permanent injury to the Demised Premises and the
means of access thereto, shall be permanently abated, and (ii) a just proportion
of the remainder of the Yearly Fixed Rent and Additional Rent, according to the
nature and extent of the taking, appropriation or condemnation and the resultant
injury sustained by the Premises and the means of access thereto, shall be
abated until what remains of the Premises and the means of access thereto shall
have been restored as fully as may be for permanent use and occupation by Tenant
hereunder. Except for any award specifically reimbursing Tenant for moving or
relocation expenses and Tenant's removable fixtures and equipment, there are
expressly reserved to Landlord all rights to compensation and damages created,
accrued or accruing by reason of any such taking, appropriation or condemnation,
in implementation and in confirmation of which Tenant does hereby acknowledge
that Landlord shall be entitled to receive and retain all such compensation and
damages, grants to Landlord all and whatever rights (if any) Tenant may have to
such compensation and damages, and agrees to execute and deliver all and
whatever further instruments of assignment as Landlord may from time to time
request. In the event of any taking of the Demised Premises or any part thereof
for temporary use, (i) this Lease shall be and remain unaffected thereby, and
(ii) Tenant shall be entitled to receive for itself any award made for such use,
provided, that if any taking is for a period extending beyond the Term of this
Lease, such award shall be apportioned between Landlord and Tenant as of the
Termination Date.

19.  DEFAULT

     19.1 Conditions of Limitation - Re-entry - Termination. This Lease and the
          -------------------------------------------------
herein term and estate are upon the condition that if (a) Tenant shall neglect
or fail to perform or observe any of the Tenant's covenants herein, including
(without limitation) the covenants with regard to the payment of Rent on or
before ten (10) days of its due date; or (b) Tenant shall be involved in
financial difficulties as evidenced by an admission in writing by Tenant of
Tenant's inability to pay its debts generally as they become due, or by the
making or offering to make a composition of its debts with its creditors; or (c)
Tenant shall make an assignment or trust mortgage, or other conveyance or
transfer of like nature, of all or a substantial part of its property for the
benefit of its creditors, or (d) the leasehold hereby created shall be taken on
execution or by other process of law and shall not be revested in Tenant within
sixty (60) days thereafter; or (e) a receiver, sequester, trustee or similar
officer shall be appointed by a court of competent jurisdiction to take charge
of all or a substantial part of Tenant's property and such appointment shall not
be vacated within sixty (60) days or (f) any proceeding shall be instituted by
or against Tenant pursuant to any of the provisions of any Act of Congress or
State law relating to bankruptcy, reorganization, arrangements, compositions or
other relief from creditors, and, in the case of any such proceeding instituted
against it, if Tenant shall fail to have such proceeding dismissed within thirty
(30) days or if Tenant is adjudged bankrupt or insolvent as a result of any such
proceeding; or (g) any event shall occur or any contingency shall arise whereby
this Lease, or the term and estate thereby created would (by operation of law or
otherwise) devolve upon or pass to any person, firm or corporation other than
Tenant, except as expressly permitted under Article 14 hereof; or (h) Tenant
shall vacate all or substantially all of the Demised Premises then, and in any
such event (except as hereinafter in Article 19.2 otherwise provided) Landlord
may, in a manner consistent with applicable law, immediately or at any time
thereafter declare this Lease terminated by notice 

                                       28
<PAGE>
 
to Tenant or, without further demand or notice, enter into and upon the Demised
Premises (or any part thereof in the name of the whole), and in either such case
(and without prejudice to any remedies which might otherwise be available for
arrears of rent or other charges due hereunder or preceding breach of covenant
and without prejudice to Tenant's liability for damages as hereinafter stated),
this Lease shall terminate. The words "re-entry" and "re-enter" as used in this
Lease are not restricted to their technical legal meaning.

     19.2 Damages - Assignment for Benefit of Creditors. For the more effectual
          ---------------------------------------------
securing by Landlord of the rent and other charge and payments reserved
hereunder, it is agreed as a further condition of this Lease that if at any time
Tenant shall make an assignment of its property for the benefit of its creditors
under the terms of which the debts provable by its creditors shall be debts
provable against the estate of insolvent debtors either under the laws of the
Commonwealth of Massachusetts or under some law or laws other than the
Bankruptcy Code as now or hereafter enacted, then and in any such case the same
shall constitute a breach of this Lease, and the term and estate hereby created
shall terminate ipso facto, without entry or other action by Landlord; and
notwithstanding any other provisions of this Lease Landlord shall forthwith upon
such termination, without prejudice to any remedies which might otherwise be
available for arrears of rent or other charges due hereunder or preceding breach
of this Lease, be ipso facto entitled to recover as liquidated damages the sum
of (a) the amount by which, at the time of such termination of this Lease, (i)
the aggregate of the Rent projected over the period commencing with such
termination and ending with the Termination Date stated in Article 1 exceeds
(ii) the aggregate projected rental value of the Demised Premises for such
period and (b) (in view of the uncertainty of prompt re-letting and the expense
entailed in re-letting the Demised Premises) an amount equal to the Rent payable
for and in respect of the calendar year next preceding the date of termination,
as aforesaid. Upon such termination Landlord, may immediately or at any time
thereafter, without demand or notice, enter into or upon the Demised Premises
(or any part thereof in the name of the whole), and (without being taken or
deemed to be guilty of any manner of trespass or conversion, and without being
liable to indictment, prosecution or damages thereof) may, forcibly if
necessary, expel Tenant and those claiming under Tenant from the Demised
Premises and remove therefrom the effects of Tenant and those claiming under
Tenant.

     19.3 Damages - Termination. Upon the termination of this Lease under the
          ---------------------
provisions of this Article, then except as hereinabove in Section 19.2 otherwise
provided, Tenant shall pay to Landlord the Rent payable by Tenant to Landlord up
to the time of such termination, shall continue to be liable for any preceding
breach of covenant, and in addition, shall pay to Landlord as damages, at the
election of Landlord,

          either:

          (x) the amount by which, at the time of the termination of this Lease
(or at any time thereafter if Landlord shall have initially elected damages
under Subparagraph (y), below), (i) the aggregate of the Rent projected over the
period commencing with such time and ending on the originally scheduled
Termination Date as stated in Article 1 exceeds (ii) the aggregate projected
rental value of the Demised Premises for such period,

                                       29
<PAGE>
 
          or,

          (y) amounts equal to the Rent which would have been payable by Tenant
had this Lease not been so terminated, payable upon the due dates therefor
specified herein following such termination and until the originally scheduled
Termination Date as specified in Article l, provided, however, if Landlord shall
re-let the Demised Premises during such period, that Landlord shall credit
Tenant with the net rents received by Landlord from such re-letting, such net
rents to be determined by first deducting from the gross rents as and when
received by Landlord from such re-letting the expenses incurred or paid by
Landlord terminating this Lease, as well as the expenses of re-letting,
including altering and preparing the Demised Premises for new tenants, brokers'
commissions, and all other similar and dissimilar expenses properly chargeable
against the Demised  Premises and the rental therefrom, it being understood that
any such re-letting may be for a period equal to or shorter or longer than the
remaining term of this Lease; and provided, further, that (i) in no event shall
Tenant be entitled to receive any excess of such net rents over the sums payable
by Tenant to Landlord hereunder and (ii) in no event shall Tenant be entitled in
any suit for the collection of damages pursuant to this Subparagraph (y) to a
credit in respect of any net rents from a re-letting except to the extent that
such net rents are actually received by Landlord prior to such determination.
If the Demised Premises or any part thereof should be re-let in combination with
other space, then proper apportionment on a square foot area basis shall be made
of the rent received from such re-letting and of the expenses of re-letting.

     Suit or suits for the recovery of such damages, or any installments
thereof, may be brought by Landlord from time to time at its election, and
nothing contained herein shall be deemed to require Landlord to postpone suit
until the date when the term of this Lease would have expired if it had not been
terminated hereunder.

     Nothing herein contained shall be construed as limiting or precluding the
recovery by Landlord against Tenant of any sums or damages to which, in addition
to the damages particularly provided above, Landlord may lawfully be entitled by
reason of any default hereunder on the part of Tenant.

     19.4 Fees and Expenses. If Tenant shall default in the performance of any
          -----------------
covenant on Tenant's part to be performed as in this Lease contained, Landlord
may immediately, or at any time thereafter, without notice, perform the same for
the account of Tenant. If Landlord at any time is compelled to pay or elects to
pay any sum of money, or do any act which will require the payment of any sum of
money, by reason of the failure of Tenant to comply with any provision hereof,
or if Landlord is compelled to or does incur any expense, including reasonable
attorneys' fees, in instituting, prosecuting and/or defending any action or
proceeding instituted by reason of any default of Tenant hereunder, Tenant shall
on demand pay to Landlord by way of reimbursement the sum or sums so paid by
Landlord with all interest, costs and damages. Without limiting the generality
of the foregoing, in the event that any Rent is in arrears by more than ten (10)
days after written notice thereof by Landlord to Tenant, Tenant shall pay, as
Additional Rent, a delinquency charge equal to one and one-half percent (1-1/2%)
of the arrearage 

                                       30
<PAGE>
 
for each calendar month (or fraction thereof) during which it remains unpaid.

     19.5 Landlord's Remedies Not Exclusive. The specified remedies to which
          ---------------------------------
Landlord may resort hereunder are cumulative and are not intended to be
exclusive of any remedies or means of redress to which Landlord may at any time
be lawfully entitled, and Landlord may invoke any remedy (including the remedy
of specific performance) allowed at law or in equity as if specific remedies
were not herein provided for.

     19.6 Grace Period. Notwithstanding anything to the contrary in this Article
          ------------
contained, Landlord agrees not to take any action to terminate this Lease (a)
for default by Tenant in the payment when due of Rent, if Tenant shall cure such
default within ten (10) days after written notice thereof given by Landlord to
Tenant, or (b) for default by Tenant in the performance of any other covenant,
if Tenant shall cure such default within a period of thirty (30) days after
written notice thereof given by Landlord to Tenant (except where the nature of
the default is such that remedial action should appropriately take place sooner
as indicated in such written notice), or with respect to covenants other than to
pay a sum of money within such additional period as may reasonably be required
to cure such default if (because of governmental restrictions or any other cause
beyond the reasonable control of Tenant) the default is of such a nature that it
cannot be cured within such thirty (30)-day period, provided, however, (1) that
there shall be no extension of time beyond such thirty (30)-day period for
curing of any such default unless, not more than ten (10) days after the receipt
of the notice of default, Tenant in writing (i) shall specify the cause on
account of which the default cannot be cured during such period and shall advise
Landlord of its intention duly to institute all steps necessary to cure the
default and (ii) shall as soon as may be reasonable, duly institute and
thereafter diligently prosecute to completion all steps necessary to cure such
default and, (2) that no notice of the opportunity to cure default need be
given, and no grace period whatsoever shall be allowed to Tenant, if the default
is incurable or if the covenant or condition, the breach of which gave rise to
the default, had, by reason of a breach on a prior occasion been the subject of
a notice hereunder to cure such default.

20.  END OF TERM - ABANDONED PROPERTY

     Upon the expiration or other termination of the Term of this Lease, Tenant
shall peaceably quit and surrender to Landlord the Demised Premises and all
alterations and additions thereto which Tenant is not entitled or required to
remove under the provisions of this Lease, broom clean in good order, repair and
condition excepting only reasonable use and wear and damage by fire or other
casualty for which, under other provisions of this Lease, Tenant has no
responsibility of repair or restoration.  Tenant's obligation to observe or
perform this covenant shall survive the expiration or other termination of the
term of this Lease.

     Any personal property in which Tenant has an interest which shall remain in
the Building or on the Demised Premises after the expiration or termination of
the Term of this Lease shall be conclusively deemed to have been abandoned, and
may be disposed of in such manner as Landlord may see fit; provided, however,
notwithstanding the foregoing, that Tenant will, upon request of  Landlord made
not later than thirty (30) days after the expiration or termination of the term

                                       31
<PAGE>
 
hereof, promptly remove from the Building any such personal property or, if any
part thereof shall be sold, that Landlord may receive and retain the proceeds of
such sale and apply the same, at its option, against the expenses of the sale,
the cost of moving and storage, any arrears of Rent payable hereunder by Tenant
to Landlord and any damages to which Landlord may be entitled under Article 19
hereof or pursuant to law, with the balance if any, to be paid to Tenant.

21.  RIGHTS OF MORTGAGEES

     21.1 Superiority of Lease. Except as provided in Section 21.7 hereof and to
          --------------------
the extent that it may be provided otherwise by written agreement between Tenant
and a Mortgagee, this Lease shall be superior, and shall not be subordinated, to
a Mortgage or to any other voluntary lien or encumbrance affecting the Land or
Building or any part thereof, provided, however, that such Mortgage shall be
superior, and shall not be subordinated, to this Lease with respect to the
following:

          (a) the prior right and claim under and the prior lien of said
Mortgage in, to and upon any award or other compensation heretofore or hereafter
to be made for any taking by eminent domain of any part of the Demised Premises,
and as to the right of disposition thereof in accordance with the provisions of
the said Mortgage; or

          (b) the prior right and claim under the prior lien of the said
Mortgage, in, to and upon any proceeds payable under all policies of fire and
rent insurance upon the Demised Premises and as to the right of disposition
thereof in accordance with the terms of said Mortgage; and


          (c) any lien, right, power or interest, if any, which may have arisen
or intervened in the period between the recording of the said Mortgage and the
execution of this Lease.

     21.2 Entry and Possession. Upon entry and taking possession of the Property
          --------------------
by a Mortgagee, for the purpose of foreclosure or otherwise, such Mortgagee
shall have all the rights of Landlord, and shall be liable to perform all the
obligations of Landlord arising and accruing during the period of such
possession by such Mortgagee.

     21.3 Right to Cure. No act or failure to act on the part of Landlord which
          -------------
would entitle Tenant under the terms of this Lease, or by law, to be relieved of
Tenant's obligations hereunder or to terminate this Lease, shall result in a
release or termination of such obligations or a termination of this Lease unless
(i) Tenant shall have first given written notice of Landlord's act or failure to
act to first Mortgagees of record, if any, and to any other Mortgagees of record
on the Term Commencement Date of the Lease or whom Tenant has been given written
notice, specifying the act or failure to act on the part of Landlord which could
or would give basis to Tenant's rights; and (ii) such Mortgagees, after receipt
of such notice, have failed or refused to correct or cure the condition
complained of within a reasonable time thereafter, but nothing 

                                       32
<PAGE>
 
contained in this paragraph shall be deemed to impose any obligation on any such
Mortgagees to correct or cure any such condition. "Reasonable time" as used
above means and includes a reasonable time to obtain possession of the Land and
Building if any such Mortgagee elects to do so and a reasonable time to correct
or cure the condition if such condition is determined to exist.

     21.4 Prepaid Rent. No Rent shall be paid more than thirty (30) days prior
          ------------
to the due dates thereof and, as to a first Mortgagee of record and any other
Mortgagees of whom Tenant has been given written notice, payments made in
violation of this provision shall (except to the extent that such rents are
actually received by such Mortgagee) be a nullity as against such Mortgagee and
Tenant shall be liable for the amount of such payments to such Mortgagee.

     21.5 Continuing Offer. The covenants and agreements contained in this Lease
          ----------------
with respect to the rights, powers and benefits of a Mortgagee (particularly,
without limitation thereby, the covenants and agreements contained in this
Article) constitute a continuing offer to any person, corporation or other
entity, which by accepting or requiring an assignment of this Lease or by entry
or foreclosure assumes the obligations herein set forth with respect to such
Mortgagee; every such Mortgagee is hereby constituted a party to this Lease as
an obligee hereunder to the same extent as though its name was written hereon as
such and such Mortgagee shall be entitled to enforce such provisions in its own
name.

     21.6 Subordination. Notwithstanding the foregoing provisions of this
          -------------
Article, Tenant agrees, at the request of Landlord or any Mortgagee, to execute
and deliver promptly any certificate or other instrument which Landlord or such
Mortgagee may request subordinating the Lease and all rights of Tenant under the
Lease to any Mortgage, and to all advances made under such mortgage, provided
that (i) the holder of any such Mortgage shall execute and deliver to Tenant a
nondisturbance agreement to the effect that, in the event of any foreclosure of
such Mortgage, such holder will not name Tenant as a party defendant to such
foreclosure nor disturb its possession under the Lease, or (ii) any such
Mortgage shall contain provisions substantially to the same effect as those
contained in such a nondisturbance agreement.
 
     21.7 Limitations on Liability. Nothing contained in the foregoing Section
          ------------------------
21.6 or in any such nondisturbance agreement or nondisturbance provision shall,
however, affect the prior rights of the holder of any Mortgage with respect to
the proceeds of any award in condemnation or of any fire insurance policies
affecting the Building, or impose upon any such holder any liability (i) for the
erection or completion of the Building, or (ii) in the event of damage or
destruction to the Building or the Demised Premises by fire or other casualty,
for any repairs, replacements, rebuilding or restoration except such repairs,
replacements, rebuilding or restoration as can reasonably be accomplished from
the net proceeds of insurance actually receive by, or made available to, such
holder, or (iii) for any default by Landlord under the Lease occurring prior to
any date upon which such holder shall become Tenant's Landlord, or (iv) for any
credits, offsets or claims against the rent under the Lease as a result of any
acts or omissions of Landlord committed or omitted prior to such date, or (v)
for return of any security deposit or other funds unless the same shall have
been received by such holder, and any such agreement or provision may so state.

                                       33
<PAGE>
 
22.  QUIET ENJOYMENT

     Landlord covenants that if, and so long as, Tenant keeps and performs each
and every covenant, agreement, term, provision and condition herein contained on
the part and on behalf of Tenant to be kept and performed, Tenant shall quietly
enjoy the Demised Premises from and against the claims of all persons claiming
by, through or under Landlord subject, nevertheless, to the covenants,
agreements, terms, provisions and conditions of this Lease and to the mortgages,
ground leases and/or underlying leases to which this Lease is subject and
subordinate.

23.  ENTIRE AGREEMENT - WAIVER - SURRENDER

     23.1 Entire Agreement. This Lease and the Exhibits made a part hereof
          ----------------
contain the entire and only agreement between the parties and any and all
statements and representations, written and oral, including previous
correspondence and agreements between the parties hereto, are merged herein.
Tenant acknowledges that all representations and statements upon which it relied
in executing this Lease are contained herein and that Tenant in no way relied
upon any other statements or representations, written or oral. Any executory
agreement hereafter made shall be ineffective to change, modify, discharge or
effect an abandonment of this Lease in whole or in part unless such executory
agreement is in writing and signed by the party against whom enforcement of the
change, modification, discharge or abandonment is sought. Nothing herein shall
prevent the parties from agreeing to amend this Lease and the Exhibits made part
hereof as long as such amendment shall be in writing and shall be duly signed by
both parties.

     23.2 Waiver by Landlord. The failure of Landlord to seek redress for
          ------------------
violation, or to insist upon the strict performance, of any covenant or
condition of this Lease, or any of the Rules and Regulations promulgated
hereunder, shall not prevent a subsequent act, which would have originally
constituted a violation, from having all the force and effect of an original
violation. The receipt by Landlord of rent with knowledge of the breach of any
covenant of this Lease shall not be deemed a waiver of such breach. The failure
of Landlord to enforce any of such Rules and Regulations against Tenant and/or
any other tenant or subtenant in the Building shall not be deemed a waiver of
any such Rules and Regulations. No provisions of this Lease shall be deemed to
have been waived by Landlord unless such waiver be in writing signed by
Landlord. No payment by Tenant or receipt by Landlord of a lesser amount than
the monthly rent herein stipulated shall be deemed to be other than on account
of the stipulated rent, nor shall any endorsement or statement on any check or
any letter accompanying any check or payment as rent be deemed an accord and
satisfaction, and Landlord may accept such check or payment without prejudice of
Landlord's right to recover the balance of such rent or pursue any other remedy
in this Lease provided.

     23.3 Surrender. No act or thing done by Landlord during the term hereby
          ---------
demised shall be deemed an acceptance of a surrender of the Demised Premises,
and no agreement to accept such surrender shall be valid, unless in writing
signed by Landlord. No employee of Landlord or of Landlord's agents
shall have any power to accept the keys of the Demised Premises prior to the

                                       34
<PAGE>
 
termination of this Lease. The delivery of keys to any employee of Landlord or
of Landlord's agents shall not operate as a termination of the Lease or a
surrender of the Demised Premises. In the event that Tenant at any time desires
to have Landlord underlet the Demised Premises for Tenant's account, Landlord or
Landlord's agents are authorized to receive the keys for such purposes without
releasing Tenant from any of the obligations under this Lease, and Tenant hereby
relieves Landlord of any liability for loss of or damage to any of Tenant's
effects in connection with such underletting.

24.  INABILITY TO PERFORM - EXCULPATORY CLAUSE

     Except as otherwise expressly provided in this Lease, this Lease and the
obligations of Tenant to pay rent hereunder and perform all other covenants,
agreements, terms, provisions and conditions hereunder on the part of Tenant to
be performed shall in no way be affected, impaired or excused because Landlord
is unable to fulfill any of its obligations under this Lease or is unable to
supply or is delayed in supplying any service expressly or impliedly to be
supplied or is unable to make or is delayed in making any repairs, replacements,
additions, alterations, improvements or decorations or is unable to supply or is
delayed in supplying any equipment or fixtures if Landlord is prevented or
delayed from doing so by reason of strikes or labor troubles or any other
similar or dissimilar cause whatsoever beyond Landlord's reasonable control,
including but not limited to, governmental preemption in connection with a
national emergency or by reason of any rule, order or regulation of any
department or subdivision thereof of any governmental agency or by reason of the
conditions of supply and demand which have been or are affected by war,
hostilities or other similar or dissimilar emergency.  In each such instance of
inability of Landlord to perform, Landlord shall exercise reasonable diligence
to eliminate the cause of such inability to perform.

     Tenant shall neither assert nor seek to enforce any claim for breach of
this Lease against any of Landlord's assets other than Landlord's interest in
the Building of which the Premises are a part and in the rents, issues and
profits thereof, and Tenant agrees to look solely to such interest for the
satisfaction of any liability of Landlord under this Lease, it being
specifically agreed that in no event shall Landlord (which term shall include
without limitation any of the officers, trustees, directors, partners,
beneficiaries, joint venturers, members, stockholders or other principals or
representatives, disclosed or undisclosed of Landlord or any managing agent)
ever be personally liable for any such liability.  This paragraph shall not
limit any right that Tenant might otherwise have to obtain injunctive relief
against Landlord or to take any other action which shall not involve the
personal liability of Landlord to respond in monetary damages from Landlord's
assets other than the Landlord's interest in said real estate, as aforesaid.  In
no event shall Landlord ever be liable for consequential damages.

25.  BILLS AND NOTICES

     Any notice, consent, request, bill, demand or statement hereunder by either
party to the other party shall be in writing and, if received at Landlord's or
Tenant's address, shall be deemed to have been duly given when either delivered
or served personally or mailed in a postpaid envelope, deposited in the United
States mails addressed to the respective party at its address as 

                                       35
<PAGE>
 
stated in Article 1, or if any address for notices shall have been duly changed
as hereinafter provided, if mailed as aforesaid to the party at such changed
address. Either party may at any time change the address for such notices,
consents, requests, bills, demands or statements by delivering or mailing, as
aforesaid, to the other party a notice stating the change and setting forth the
changed address, provided such changed address is within the United States.

     All bills and statements for reimbursement or other payments or charges due
from Tenant to Landlord hereunder shall set forth in reasonable detail the
particulars relating thereto and shall be due and payable in full thirty (30)
days, unless herein otherwise provided, after submission thereof by Landlord to
Tenant.  Landlord shall, at Tenant's reasonable request, promptly furnish Tenant
with such additional reasonable details relating thereto as Tenant shall
reasonably request.  Tenant's failure to make timely payment of any amounts
indicated by such bills and statements, whether for work done by Landlord at
Tenant's request, reimbursement provided for by this Lease or for any other sums
properly owing by Tenant to Landlord, shall be treated as a default in the
payment of Rent, in which event Landlord shall have all rights and remedies
provided in this Lease for the nonpayment of Rent.  Unless otherwise directed by
Tenant, a copy of all default notices to Tenant shall be forwarded to Director
of Real Estate, Focal Communications Corporation, 200 North LaSalle Street,
Suite 800, Chicago, Illinois 60601.

26.  PARTIES BOUND - SEIZING OF TITLE

     The covenants, agreements, terms, provisions and conditions of this Lease
shall bind and benefit the successors and assigns of the parties hereto with the
same effect as if mentioned in each instance where a party hereto is named or
referred to, except that no violation of the provisions of Article 14 hereof
shall operate to vest any rights in any successor or assignee of Tenant and that
the provisions of this Article shall not be construed as modifying the
conditions of limitation contained in Article 19 hereof.

     If in connection with or as a consequence of the sale, transfer or other
disposition of the real estate (Land and/or Building either or both, as the case
may be) of which the Demised Premises are a part Landlord ceases to be the owner
of the reversionary interest in the Premises, Landlord shall so notify Tenant
and Landlord shall be entirely freed and relieved from the performance and
observance thereafter of all covenants and obligations hereunder accruing
thereafter on the part of Landlord to be performed and observed, it being
understood and agreed in such event (and it shall be deemed and construed as a
covenant running with the land) that the person succeeding to Landlord's
ownership of said reversionary interest shall thereupon and thereafter assume,
and perform and observe, any and all of such covenants and obligations of
Landlord.

27.  MISCELLANEOUS

     27.1 Separability. If any provision of this Lease or portion of such
          ------------
provision or the application thereof to any person or circumstance is for any
reason held invalid or unenforceable, the remainder of the Lease (or the
remainder of such provision) and the application thereof to 

                                       36
<PAGE>
 
other persons or circumstances shall not be affected thereby.

     27.2 Captions.  The captions are inserted only as a matter of convenience
          --------                                                              
and for reference, and in no way define, limit or describe the scope of this
Lease nor the intent of any provision thereof.

     27.3 Broker.  Each party represents and warrants that it has not directly
          ------                                                                
or indirectly dealt, with respect to the leasing of office space in the
Building, with any broker or had its attention called to the Premises or other
space to let in the Building, by any broker other than the Broker(s) (if any)
listed in Article 1 whose commission shall be the responsibility of Landlord.
Each party agrees to exonerate and save harmless and indemnify the other against
any claims for a commission by any other broker, person or firm with whom such
party has dealt in connection with the execution and delivery of this Lease or
out of negotiations between Landlord and Tenant with respect to the leasing of
other space in the Building.

     27.4 Governing Law. This lease is made pursuant to, and shall be governed
          -------------
by, and construed in accordance with, the laws of the Commonwealth of
Massachusetts.

     27.5 Assignment of Rents. With reference to any assignment by Landlord of
          -------------------
its interest in this Lease, or the Rent payable hereunder, conditional in nature
or otherwise, which assignment is made to or held by a bank, trust company,
insurance company or other institutional lender holding a Mortgage on the
Building, Landlord and Tenant agree:

          (a) that the execution thereof by Landlord and acceptance thereof by
such Mortgagee shall never be deemed an assumption by such Mortgagee of any of
the obligations of the Landlord thereunder, unless such Mortgagee shall, by
written notice sent to the Tenant, specifically otherwise elect; and

          (b) that, except as aforesaid, such Mortgagee shall be treated as
having assumed the Landlord's obligations thereunder only upon foreclosure of
such Mortgagee's Mortgage and the taking of possession of the Demised Premises
after having given notice of its exercise of the option stated in Article 21
hereof to succeed to the interest of the Landlord under this Lease.

     27.6 Parking.  Landlord shall allocate to Tenant the number of non-
          -------
exclusive Parking Spaces indicated in Article 1.  Landlord may, pursuant to
Section 15.1, establish Rules and Regulations relative to all parking areas
serving Building tenants and may further engage the services of an independent
contractor to administer and control access to said parking areas.  Landlord or
said independent contractor shall impose separate charges for use of said
parking areas, and such charges shall be payable by Tenant as Additional Rent
with respect to Tenant's Parking Spaces.  As of the Term Commencement Date the
monthly charge for each Parking Space situated in the garage facility serving
the Building shall be One Hundred Sixty Dollars ($160).  Thereafter, the monthly
charge shall be as from time to time established by Landlord or said independent
contractor as the then prevailing monthly parking charge for the Building.
Tenant acknowledges that Landlord has informed Tenant that Landlord intends to
allocate in its 

                                       37
<PAGE>
 
tenant leases up to one hundred twenty-five percent (125%) of the actual parking
spaces servicing the Building. It is further acknowledged and agreed that as a
consequence of such over-allocation of parking spaces there may occasionally
occur instances in which the number of parking spaces actually available to
Tenant shall be less than the Parking Spaces to which Tenant is entitled under
this Lease. Landlord shall incur no liability to Tenant as a consequence of such
over-allocation of parking spaces.

     27.7 Notice of Lease. Neither party shall record this Lease in any Registry
          ---------------
of Deeds or Registry District; provided, however, that concurrently with the
execution hereof, Landlord and Tenant shall execute and deliver a recordable
Notice of Lease in the form prescribed by Chapter 183, Section 4 of the
Massachusetts General Laws for filing with Middlesex South Registry of Deeds.

     27.8 Financial Statements. If requested by Landlord, Tenant shall furnish
          --------------------
to Landlord promptly after they are available to Tenant copies of Tenant's
annual financial statements (audited, if available) and unaudited monthly
financial statements and such other financial statements as Tenant shall furnish
from time to time to any lender and/or equity holder of Tenant. It is understood
and agreed that Landlord may furnish copies of any and all of such financial
statements to one or more of its mortgagees.

     27.9 Holding Over. Any holding over by Tenant after the expiration of the
          ------------
Term of this Lease shall be treated as a tenancy at sufferance at twice the
Yearly Fixed Rent and Additional Rent herein provided (prorated on a daily
basis) and shall otherwise be on the terms and conditions set forth in this
Lease, as far as applicable.

                                       38
<PAGE>
 
     IN WITNESS WHEREOF, Landlord and Tenant have caused this instrument to be
executed under seal, all as of the day and year first above written.


                         RIVERFRONT OFFICE PARK ASSOCIATES II
                         LIMITED PARTNERSHIP

                         By:  DARVEL REALTY TRUST
                               Managing General Partner


                         By: /s/ Michael P. Sullivan
                            ------------------------------------------------
                            Michael P. Sullivan, Vice President


                         FOCAL COMMUNICATIONS CORPORATION

 
                         By: /s/ Brian F. Addy
                            ------------------------------------------------
                            Its Executive Vice President

                                       39
<PAGE>
 
                                   EXHIBIT A
                                   ---------

                       PLAN OF FOCAL COMMUNICATION CORP.
                                   13,274 SF
<PAGE>
 
                                   EXHIBIT B
                                   ---------

                              DESCRIPTION OF LAND
                              -------------------


          A certain parcel of land in the City of Cambridge, Middlesex County,
Massachusetts, bounded and described as follows:

     SOUTHWESTERLY            at the intersection of Main Street and First
                              Street, by four lines measuring 44.72 feet, 129.49
                              feet, 24.15 feet, and 41.16 feet, respectively;

     SOUTHERLY                by Main Street by a line measuring 404.86 feet;

     WESTERLY                 by Lot 1, by a line measuring 154.28 feet; and

     NORTHERLY                by the Broad Canal, 594.60 feet.

     Said parcel is shown as Lot 2 on a "Subdivision Plan of Land in Cambridge,
Mass. (Middlesex County)", dated April 24, 1981, and revised September 4, 1981,
drawn by Boston Survey Consultants, and prepared for Darvel Realty Trust,
recorded with Middlesex Southern District Registry of Deeds in Book 14412, Page
199.

<PAGE>
 
                                   EXHIBIT C
                                   ---------

                               AUDIT PROCEDURES
                               ----------------


1.   Such documentation and calculation shall be made available to Tenant at the
offices where Landlord keeps such records in Cambridge/Boston, Massachusetts
during normal business hours within a reasonable time (not to exceed ten (10)
business days) after Landlord receives a written request from Tenant to make
such examination.

2.   Tenant shall have the right to make such examination no more than once in
respect of any fiscal tax year or calendar operation year, as the case may be,
in which Landlord has given Tenant a statement of the actual amount of taxes or
operating expenses, as the case may be, for such year.

3.   Any request for examination in respect of any such calendar or fiscal year
shall be made no more than sixty (60) days after Landlord advises Tenant of the
actual amount of taxes or operating expenses in respect of such period.

4.   Such examination may be made only by an independent certified public
accounting firm approved by Landlord, which consent shall not be unreasonably
withheld or delayed, paid by Tenant on a straight fee (non-contingent fee)
basis.

5.   As a condition of performing any such examination, Tenant and its examiners
shall be required to execute and deliver to Landlord an agreement, in form
reasonable acceptable to Landlord, agreeing to keep confidential any information
which it discovers about Landlord or the Building in connection with such
examination.

<PAGE>
 
                                   EXHIBIT D
                                   ---------


                     PROCEDURE FOR ALLOCATION OF COSTS OF
                        ELECTRIC POWER USAGE BY TENANTS

     1.  Main electric service to the Building is provided and metered by the
local utility company.  Building energy consumption via switch gear MS1 & MS1A
will be billed to and paid for by Landlord at rates established by the utility
company.

     Tenant shall pay for its electricity directly to the electric utility
supplying power for dedicated preferred source switch gear MS2 (room 126) fed
from Cambridge Electric Light Company (CELCO circuit #55).  This power source is
dedicated solely for operation of the computer facilities on the eleventh (11th)
floor of the Building and the associated chilled water plant located on the
fourteenth (14th) floor and the roof of the Building and is separately metered
by Cambridge Electric Light Company (meter #8016527).

     (Separate electric service from the utility company directly to tenants may
be made available to retail tenants on the ground floor if Landlord determines
this to be appropriate to the tenancy involved.)

     2.  In order to allocate charges for electric service fairly among tenants
in relation to the relative amounts of electricity used by each tenant,
additional meters (known as "check meters") have been installed by Landlord for
each tenant to measure all electricity provided for lights and power to that
tenant.  This shall not, however, include the following, which shall be wired
from the main building service and not through the check meters:  stairwell and
emergency lights; elevators; heat pumps and HVAC in the Building; exterior
lighting; and all main building mechanical systems (common areas on each floor,
including the elevator lobby, corridors, and bathrooms, will have service
through the check meters on each floor) (the "Basic Building Electricity") and
which shall be separately metered.

     3.  Additional check meters may be installed by Landlord where necessary to
assure measurement of all electric service to tenant areas (e.g., in the case of
separate dedicated circuits to computer rooms, cafeterias, or other special
purpose facilities).  Ground floor tenant space will be check metered if it is
not separately metered.  In addition, further modification to the number and
location of check meters may be made by Landlord if required to improve the
quality of information obtained thereby.

     4.  Landlord will cause the check meters to be read monthly by its
employees and will perform an analysis of the information for the purpose of
determining an equitable allocation of the costs of electric service among the
tenants in the Building in relation to the respective amounts of usage of
electricity by those tenants.

     5.  Each tenant's allocable share ("Tenant's Allocable Electricity Cost"),
shall be determined by Landlord on the following basis:
<PAGE>
 
     a.        The total kilowatt hour usage for the period under evaluation
               shall be established for each check meter and also for the
               Building as a whole by a reading of the main building meter for
               that period.

     b.        The cost of the total amount of electricity supplied for usage by
               tenants during the period (exclusive of the Base Building
               Electricity) (herein called "Tenant Electricity") shall be
               determined by multiplying the total cost of electricity as
               invoiced by the utility company for the same period by a
               fraction, the numerator of which is the total amount of kilowatt
               hour usage as measured by all of the Tenant Electricity check
               meters in the Building and the denominator of which is the total
               amount of kilowatt hour usage for the Building as measured by the
               main building electric meter.

     c.        Tenant's Allocable Electricity Cost for the period shall be
               determined by multiplying the total costs of Tenant Electricity
               by a fraction, the numerator of which is the kilowatt hour usage
               of Tenant Electricity by said tenant (calculated as the sum of
               kilowatt hour usage during the period measured by all check
               meters serving its premises) and the denominator of which is the
               total kilowatt hour usage of Tenant Electricity for the same
               period.

     d.        Where part or all of the rentable area on a floor has been
               occupied by a tenant for less than all of the period for which
               said Tenant's Allocable Electricity Cost is being calculated,
               appropriate and equitable modifications shall be made to the
               allocation formula so that each tenant's allocable share of costs
               equitably reflects its period of occupancy, provided that in no
               event shall the total of all costs as allocated to tenants be
               less than the total cost of Tenant Electricity for said period.

     6.  All costs of Base Building Electricity to Landlord shall be treated as
part of the Operating Costs of the Building for purposes of determining the
allocation of those costs.

                                       2
<PAGE>
 
                                   EXHIBIT E
                                   ---------

                            CLEANING SPECIFICATIONS
                            -----------------------

OFFICE AREA:
- ----------- 

DAILY - Monday through Friday inclusive, Massachusetts legal holidays excluded.
- -----                                                                          

1.   Empty all waste receptacles and remove trash to designated area, wash
     receptacles as necessary.

2.   Empty and wipe all ashtrays.

3.   Vacuum all rugs and carpets.

4.   Hand dust and wipe clean with treated cloths all horizontal surfaces,
     including furniture, office equipment, window sills, door ledges, chair
     rails and converter tops, within normal reach.

5.   Wash and clean all bathrooms and water fountains.

6.   Remove and dust under all desk equipment and telephones and replace same.

7.   Wipe clean all brass and other bright work.

8.   Sweep and dust mop all uncarpeted areas using a dust treated mop.

9.   Hand dust all grill work within normal reach.

WEEKLY
- ------

1.   Dust coat racks and the like.

2.   Remove all finger marks from private entrance doors, light switches and
     doorways.

QUARTERLY - Render high dusting not reached in daily cleaning to include:
- ---------                                                                

1.   Dusting all pictures frames, charts, graphs and similar wall hangings.

2.   Dusting all vertical surfaces such as walls, partitions and doors.

3.   Dusting of all venetian blinds.

TWICE PER YEAR - Wash interior and exterior of perimeter windows.
- --------------                                                   
<PAGE>
 
MAIN LOBBY, ELEVATORS, BUILDING EXTERIOR AND CORRIDORS - CONTINUED
- ------------------------------------------------------------------

4.   Spot clean any metal work in lobby.

5.   Spot clean any metal work surrounding building entrance doors.

6.   Spot clean and polish guard desk.

7.   Vacuum all corridor carpets.

MONTHLY
- -------

1.   All resilient tile floors in public area are to be treated equivalent to
     spray buffing.

2.   Shampoo carpeting in elevator.

STAIRWELLS
- ----------

DAILY - Monday through Friday inclusive, Massachusetts legal holidays excluded.
- -----                                                                          

1.   Sweep all stairwells.


                                       2
<PAGE>
 
                                   EXHIBIT F
                                   ---------

                             RULES AND REGULATIONS
                             ---------------------


     1.   The sidewalks, entrances, passages, courts, elevators, vestibules,
stairways, corridors or halls of the Building shall not be obstructed or
encumbered or used for any purpose other than ingress and egress to and from the
premises demised to any tenant or occupant.

     2.   No awnings or other projections shall be attached to the outside walls
or windows of the Building without the prior consent of Landlord.  No curtains,
blinds, shades, or screens shall be attached or hung in, or used in connection
with, any window or door of the premises demised to any tenant or occupant,
without the prior consent of Landlord.  Such awnings, projections, curtains,
blinds, shades, screens, or other fixtures must be of a quality type, design and
color, and attached in a manner, approved by Landlord.

     3.  No sign, advertisement, object, notice or other lettering shall be
exhibited, inscribed, painted or affixed on any part of the outside or inside of
the premises demised to any tenant or occupant or of the Building without the
prior written consent of Landlord.  Interior signs on doors and directory
tables, if any, shall be of a size, color and style approved by Landlord.

     4.  The sashes, sash doors, skylights, windows, and doors that reflect or
admit light and air into the halls, passageways or other public places in the
Building shall not be covered or obstructed, nor shall any bottles, parcels, or
other articles be placed or stored upon on any window sills.

     5.  No show cases or other articles of any kind shall be put in front of or
affixed to any part of the exterior of the Building, nor placed in the halls,
corridors, vestibules or other parts of the Building.

     6.  The water and wash closets and other plumbing fixtures shall not be
used for any purposes other than those for which they were constructed, and no
sweepings, rubbish, rags, or other substances shall be thrown therein.

     7.  No tenant or occupant shall mark, paint, drill into, or in any way
deface any part of the Building or the premises demised to such tenant or
occupant.  No boring, cutting or stringing of wires shall be permitted, except
with the prior consent of the Landlord, and as Landlord may direct.  No tenant
or occupant shall install any resilient tile or similar floor covering in the
premises demised to such tenant or occupant except in manner approved by
Landlord.

     8.  No bicycles, vehicles or animals of any kind shall be brought into or
kept in or about the premises demised to any tenant. Bicycles may be stored in
racks, if any, furnished for such purpose by Landlord in a common area of the
Building. No cooking shall be done or permitted in the Building by any tenant
without the approval of Landlord. No tenant shall cause or permit any unusual or
objectionable odors to emanate from the premises demised to such
<PAGE>
 
tenant.

     9.   Without the prior consent of Landlord, no space in the Building shall
be used for manufacturing, or for the sale of merchandise, goods or property of
any kind at auction.

     10.  No tenant shall make, or permit to be made, any unseemly or disturbing
noises or disturb or interfere with other tenants or occupants of the Building
or neighboring buildings or premises, whether by the use of any musical
instrument, radio, television set or other audio device, unmusical noise,
whistling, singing, or in any other way.  Nothing shall be thrown out of any
doors or windows.

     11.  Each tenant must, upon the termination of its tenancy, restore to
Landlord all keys, either furnished to, or otherwise procured by, such tenant,
including without limitation, all parking pass keys, Building keys, office keys
and keys to storage areas and toilet rooms.

     12.  All removals from the Building, or the carrying in or out of the
Building or the premises demised to any tenant, of any safes, freight,
furniture, or bulky matter of any description must take place at such time and
in such manner as Landlord or its agents may determine, from time to time.
Landlord reserves the right to inspect all freight to be brought into the
Building and to exclude from the Building all freight which violates any of the
Building Rules or the provisions of such tenant's lease.

     13.  No tenant shall use or occupy, or permit any portion of the premises
demised to such tenant to be used or occupied, as an office for a public
stenographer or typist, or to a barber or manicure shop, or as an employment
bureau.  No tenant or occupant shall engage or pay any employees in the
Building, except those actually working for such tenant or occupant in the
Building, nor advertise for laborers giving an address at the Building.

     14.  No tenant or occupant shall purchase spring water, ice, food,
beverage, lighting maintenance, cleaning towels or other like service, from any
company or person not approved by Landlord, such approval not unreasonably to be
withheld.

     15.  Landlord shall have the right to prohibit any advertising by any
tenant or occupant which, in Landlord's opinion, tends to impair the reputation
of the Building or its desirability as a building for offices, and upon notice
from Landlord, such tenant or occupant shall refrain from or discontinue such
advertising.

     16.  Landlord reserves the right to exclude from the Building, between the
hours of 6:00 p.m. and 8:00 a.m. on Business Days and otherwise at all hours,
all persons who do not present a pass to the building signed by the Landlord.
Landlord will furnish passes to persons for whom any tenant requests such
passes.  Each tenant shall be responsible for all persons for whom it requests
such passes and shall be liable to Landlord for all wrongful acts of such
persons.

                                       3
<PAGE>
 
     17.  Each tenant, before closing and leaving the premises demised to such
tenant at any time, shall see that all entrance doors are locked and windows
closed.

     18.  Each tenant shall, at its expense, provide artificial light in the
premises demised to such tenant for Landlord's agents, contractors, and
employees while performing janitorial or other cleaning services and making
repairs or alterations in said premises.

     19.  No premises shall be used, or permitted to be used, for lodging or
sleeping, or for any immoral or illegal purpose.

     20.  There shall not be used in the Building, either by any tenant or
occupant or by their agents or contractors, in the delivery or receipt of
merchandise, freight or other matter, any hand trucks or other means of
conveyance, except those equipped with rubber tires, rubber side guards and such
other safeguards as Landlord may require.

     21.  Canvassing, soliciting and peddling in the Building are prohibited and
each tenant and occupant shall cooperate in seeking their prevention.

     22.  If the premises demised to any tenant become infested with vermin,
such tenant, at its sole cost and expense, shall cause its premises to be
exterminated from time to time, to the satisfaction of Landlord and shall employ
such exterminators therefor as shall be approved by Landlord.

     23.  No premises shall be used, or permitted to be used, at any time,
without the prior approval of Landlord, as a store for the sale or display of
goods, wares or merchandise of any kind, or as a restaurant, shop, booth,
bootblack or other stand, or for the conduct of any business or occupation which
predominantly involves direct patronage of the general public in the premises
demised to such tenant, or for manufacturing or for other similar purposes.

     24.  No tenant shall move, or permit to be moved, into or out of the
Building or the premises demised to such tenant, any heavy or bulky matter,
without the specific prior written approval of Landlord.  If any such matter
requires special handing, only a person holding a Master Rigger's License shall
be employed to perform such special handling.  No tenant shall place, or permit
to be placed on any part of the floor or floors of the premises demised to such
tenant, a load exceeding the floor load per square foot which such floor was
designed to carry and which is allowed by law.  Landlord reserves the right to
prescribe the weight and position of safes and other heavy matter, which must be
placed so as to distribute the weight.

     25.  The requirements of tenants will be attended to only upon application
at the office of the Building.  Building employees shall not be required to
perform, and shall not be requested by any tenant or occupant to perform any
work outside of their regular duties, unless under specific instructions from
the office of the managing agent of the Building.

                                       4

<PAGE>
 
                                                                 Exhibit 10.16







                                 LEASE AGREEMENT


                                 by and between


            THE EQUITABLE LIFE ASSURANCE SOCIETY OF THE UNITED STATES

                                  ("Landlord")


                                       and


                         FOCAL COMMUNICATION CORPORATION

                                   ("Tenant")


                                      dated

                                 Feb. 5, 1999


                                       for

                               Suite Number L-200


                                   containing

                    21,948 square feet of Rentable Floor Area





                                Term: 120 months
<PAGE>
 
                                TABLE OF CONTENTS
                                                                    Page
 1.      Certain Definitions                                          1
 2.      Lease of Premises                                            2
 3.      Term                                                         2
 4.      Possession                                                   2
 5.      Rental Payments                                              2
 6.      Base Rental                                                  3
 7.      Rental Adjustment                                            3
 8.      Additional Rental                                            3
 9.      Operating Expenses                                           3
10.      Tenant Taxes                                                 5
11.      Payments                                                     5
12.      Late Charges                                                 5
13.      Uses                                                         5
14.      Alterations                                                  6
15.      Repairs                                                      6
16.      Landlord's Right of Entry                                    6
17.      Insurance                                                    6
18.      Waiver of Subrogation                                        7
19.      Default                                                      7
20.      Waiver of Breach                                             8
21.      Assignment and Subletting                                    8
22.      Destruction                                                  8
23.      Landlord's Lien                                              9
24.      Services by Landlord                                         9
25.      Attorneys' Fees and Homestead                                9
26.      Time                                                         9
27.      Subordination and Attornment                                 9
28.      Estoppel Certificates                                       10
29.      No Estate                                                   10
30.      Cumulative Rights                                           10
31.      Holding Over                                                10
32.      Surrender of Premises                                       10
33.      Notices                                                     10
34.      Damage or Theft of Personal Property                        11
35.      Eminent Domain                                              11
36.      Parties                                                     11
37.      Liability of Tenant                                         11
38.      Relocation of the Premises                                  12
39.      Force Majeure                                               12
40.      Landlord's Liability                                        12
41.      Landlord's Covenant of Quiet Enjoyment                      12
42.      Security Deposits                                           12
43.      Hazardous Substances                                        13
44.      Submission of Lease                                         13
45.      Severability                                                13
46.      Entire Agreement                                            13
47.      Headings                                                    13
48.      Broker                                                      13
49.      Governing Law                                               14
50.      Authority                                                   14
51.      Joint and Several Liability                                 14
52.      Special Stipulations                                        14

         Rules and Regulations
         ---------------------
         Exhibit "A" - Legal Description
         Exhibit "B" - Floor Plan
         Exhibit "C" - Supplemental Notice
         Exhibit "D" - Landlord's Construction
         Exhibit "E" - Building Standard Services
         Exhibit "F" - Guaranty
         Exhibit "G" - Special Stipulations
         Exhibit "H" - Subordination, Non-Disturbance and Attornment Agreement
<PAGE>
 
                                LEASE AGREEMENT
                                ---------------


         THIS LEASE AGREEMENT ("Lease") is made and entered into this 5th day of
February, 1999, by and between Landlord and Tenant.


                              W I T N E S S E T H:
                              --------------------


         1.  Certain Definitions.  As used in this Lease, the following terms
shall have the meanings hereinafter ascribed thereto:

         (a)      Landlord: THE EQUITABLE LIFE ASSURANCE SOCIETY OF THE UNITED
                            STATES

         (b)      Landlord's Address:

                  3424 Peachtree Road, N.E.
                  Suite 800
                  Atlanta, Georgia 30326

         (c)      Tenant: Focal Communication Corporation, a Delaware
                          corporation

         (d)      Tenant's Address:
                                           Tenant's Additional Notice Address:
                  250 Williams Street
                  Suite L-200              with copies sent simultaneously to:
                  Atlanta, Georgia 30303   200 North LaSalle Street, Suite 800
                                           Chicago, Illinois 60601
                                           Attn: Director of Real Estate

                                           and

                                           Focal Communications Corporation
                                           200 North LaSalle Street, Suite 800
                                           Chicago, Illinois 60601
                                           Attn: Executive Vice President
         (e)      Building Address:
                  INFORUM
                  250 Williams Street
                  Atlanta, Georgia 30303

         (f)      Suite Number: L-200

         (g)      Rentable Floor Area of the Premises:

                           21,948 square feet.  Landlord and Tenant agree that
when the tenant improvements to the Premises are completed, Landlord or Tenant
may have the same remeasured by a firm reasonably acceptable to Landlord. If the
measurement (subject to verification by the other party) proves the Premises
contain more or less than 21,948 rentable square feet, Landlord and Tenant agree
to modify this Lease to reflect the accurate amount of rentable square feet and
correct the associated calculations hereunder which are based on rentable square
feet provided that such remeasurement shall not affect or impact the conversion
factor used to calculate usable square feet within the Premises or the Building.

                  (h)      Rentable Floor Area of Building:

                           Currently 720,161 square feet, however, Landlord will
increase the Rentable Floor Area of the Building following the year each of the
Bridge level and the Lobby level of the Building have been converted to office
space. Landlord shall use the same method of measurement for measuring the
Building as it used for measurement of the Premises.

                  (i) Lease Term: one hundred twenty (120) months, beginning on
         an estimated term commencement date of June 1, 1999; provided, however,
         that the actual date of commencement of the term of this Lease (the
         "Term Commencement Date") shall be the earlier of: (i) the date on
         which the Premises are "ready for occupancy" as described in Exhibit
         "D" hereof or, if such date on which the Premises would otherwise have
         been ready for occupancy is postponed due to delays caused by Tenant or
         its employees, agents or contractors, the date the Premises would
         reasonably have been expected to be ready for occupancy absent such
         delays, or (ii) the date on which Tenant takes possession and occupies
         the Premises for its business use. If for any reason the Term
         Commencement Date is postponed for more than one (1) year, Landlord
         shall have the right to terminate this Lease by written notice to
         Tenant. On or before February 1, 1999, Landlord shall give Tenant
         written permission to enter the Premises for the purpose of installing
         equipment therein or making improvements thereto but not for the
         purpose of occupying the Premises, Tenant shall comply with all terms,
         provisions and conditions of this Lease except those requiring the
         payment of Rent. The Lease Term shall end at midnight on the last day
         of the period of months hereinabove described (the "Term Expiration
         Date").

                  (j) Base Rental Rate: $19.50 per square foot of Rentable Floor
         Area of the Premises per year for years one (1) through five

                                       1
<PAGE>
 
         (5) of the Lease Term; $22.50 per square foot of Rentable Floor Area of
         the Premises per year for years six (6) through ten (10) of the Lease
         Term.

                  (k) Rental Commencement Date: Unless specifically agreed to
         the contrary in this Lease, the Rental Commencement Date shall be the
         same as the Term Commencement Date described in 1(i) above; provided,
         however, that, if Tenant is given written permission by Landlord to
         occupy a portion (but not all) of the Premises prior to the Term
         Commencement Date, the Rent payable by Tenant under this Lease shall
         commence but shall be prorated based on the number of square feet
         occupied by Tenant from time to time within the Premises until Tenant
         has occupied the entire Premises and the Term Commencement Date has
         occurred.

                  (l) Tenant Improvement Allowance: Landlord's sole obligation
to improve the Premises shall be to demolish the existing tenant improvements in
the Premises and provide Tenant a slab to slab Premises with a sprinkler system
that meets the NFPA guidelines for an unfinished floor. Landlord will provide
Tenant with a tenant improvement allowance of $5.00 per rentable square foot,
per year, for each of the initial five (5) years of the Lease Term, provided
Tenant is not in default hereunder after applicable periods of notice and cure
and provided Tenant has installed improvements of a value no less than $25.00
per rentable square foot in the Premises, excluding furniture, fixtures and
equipment. Said payment shall be made to Tenant no later than sixty (60) days
after each anniversary date of the Rental Commencement Date for the first five
(5) years of the Lease Term, not to exceed a total payment of $548,700.00. In
the event any installment of the Tenant Improvement Allowance is not paid when
due, following ten (10) days notice to Landlord, Tenant may offset such amount
from future Rent payments. Upon request, Landlord will provide Tenant up to an
additional $5.00 per rentable square foot tenant improvement allowance which
will be amortized over the Lease Term at an interest rate of ten percent (10%)
per annum.

                  (m) Security Deposits:

                            (i)  $35,665.00 [Article 42(a)]
                           (ii)  $38,409.00 [Article 42(b)]

                  (n) Broker(s): Landlord and Tenant acknowledge that Tenant is
         represented in this transaction by Tishman Real Estate Services
         ("Broker") and that Landlord is represented in this transaction by
         COMPASS Management and Leasing, Inc. ("Landlord's Agent") and that
         Landlord shall be responsible for the real estate commission payable to
         both Broker and Landlord's Agent, with said commissions to be
         documented by an agreement which shall be separate from this Lease.

         2. Lease of Premises. Landlord, in consideration of the covenants and
agreements to be performed by Tenant, and upon the terms and conditions
hereinafter stated, does hereby rent and lease unto Tenant, and Tenant does
hereby rent and lease from Landlord, certain premises (the "Premises") in the
building (the "Building") located on that certain tract of land (the "Land")
more particularly described on Exhibit "A" attached hereto and by this reference
made a part hereof, which the Premises are outlined in red or cross-hatched on
the floor plan attached hereto as Exhibit "B" and by this reference made a part
hereof, with no easement for light, view or air included in the Premises or
being granted hereunder. The "Project" is comprised of the Building, the Land,
the Building's parking facilities, any walkways, covered walkways, tunnels or
other means of access to the Building and the Building's parking facilities, all
common areas, including any lobbies or plazas, and any other improvements or
landscaping on the Land.

         3. Term. The term of this Lease (the "Lease Term") shall commence on
the Term Commencement Dates described in Article 1(i) above, and, unless sooner
terminated or extended as provided in this Lease, shall end on the Term
Expiration Date set forth in said Article 1(i). Promptly after the Term
Commencement Date, Landlord or Landlord's agent shall send to Tenant a
Supplemental Notice in the form of Exhibit "C" attached hereto and by this
reference made a part hereof, specifying the Rental Commencement Date set forth
in Article 1(k) above, the Term Expiration Date and certain other matters as
therein set forth.

         4. Possession. The obligations of Landlord and Tenant with respect to
the initial leasehold improvements to the Premises are set forth in Exhibit "D"
attached hereto and by this reference made a part hereof. Taking of possession
by Tenant shall be deemed conclusively to establish that Landlord's construction
obligations with respect to the Premises have been completed in accordance with
the plans and specifications approved by Landlord and Tenant and that the
Premises, to the extent of Landlord's construction obligations with respect
thereto, are in good and satisfactory condition.

         5. Rental Payments.

                  (a) Commencing on the Rental Commencement Date, and continuing
thereafter throughout the Lease Term, Tenant hereby agrees to pay all Rent due
and payable under this Lease. As used in this Lease, the term "Rent" shall mean
the Base Rental, the Rental Adjustment, Tenant's Forecast Additional Rental,
Tenant's Additional Rental, all as hereinafter described, and any other amounts
that Tenant assumes or agrees to pay under the provisions of this Lease that are
owed to Landlord, including, without limitation, any and all other sums that may
become due by reason of any default of Tenant or failure on Tenant's part to
comply with the agreements, terms, covenants and conditions of this Lease to be
performed by Tenant. Base Rental, together with the portion of Tenant's Forecast
Additional Rental described hereinbelow, shall be due and payable in twelve (12)
equal installments on the first day of each calendar month, commencing on the
Rental Commencement Date and continuing thereafter throughout the Lease Term and
any extensions or renewals thereof. Tenant hereby agrees to pay such Rent to
Landlord at Landlord's address as provided herein (or such other address as may
be designated by Landlord from time to time) monthly in advance. Tenant shall
pay all Rent and other sums of money as shall become due from and payable by
Tenant to Landlord under this Lease at the times and in the manner provided in
this Lease (including, without limitation, all installments of Additional Rental
described hereinbelow), without demand, set-off or counterclaim except as set
forth herein.

                                       2
<PAGE>
 
                  (b) If the Rental Commencement Date is other than the first
day of a calendar month or if this Lease terminates on a day other than the last
day of a calendar month, then the installments of Base Rental forecast for such
month or months shall be prorated on a daily basis and the installment or
installments so prorated shall be paid in advance. Also, if the Rental
Commencement Date occurs on a day other than the first day of a calendar year,
or if this Lease expires or is terminated on a day other than the last day of a
calendar year, Tenant's Additional Rental shall be prorated for such
commencement or termination year, as the case may be, by multiplying such
Tenant's Additional Rental by a fraction, the numerator of which shall be the
number of days of the Lease Term (from and after the Rental Commencement Date)
during the commencement or expiration or termination year, as the case may be,
and the denominator of which shall be 365, and the calculation described in
Article 7 hereof shall be made as soon as possible after the expiration or
termination of this Lease, Landlord and Tenant hereby agreeing that the
provisions relating to said calculation shall survive the expiration or
termination of this Lease.

         6. Base Rental. From and after the Rental Commencement Date, Tenant
shall pay to Landlord a base annual rental (herein called "Base Rental") equal
to the Base Rental Rate set forth in Article 1(j) above multiplied by the
Rentable Floor Area of the Premises as set forth in Article 1(g) above, as said
Base Rental shall increase and be adjusted pursuant to the provisions of
Sections 7 and 8 hereinbelow.

         7. Rental Adjustment. [INTENTIONALLY DELETED]

         8. Additional Rental.

                  (a) For purposes of this Lease, "Tenant's Forecast Additional
Rental" shall mean Landlord's reasonable estimate of Tenant's Additional Rental
for each calendar year or portion thereof during the Lease Term starting with
calendar year 2000. If at any time it appears to Landlord that Tenant's
Additional Rental for any calendar year following calendar year 2000 will vary
from Landlord's estimate, Landlord shall have the right to revise, by notice to
Tenant, its estimate for such year, and subsequent payments by Tenant for such
year shall be based upon such revised estimate of Tenant's Additional Rental.
Failure to make a revision contemplated by the immediately preceding sentence
shall not prejudice Landlord's right to collect the full amount of Tenant's
Additional Rental. Prior to the first day of January, 2000, and thereafter prior
to the beginning of each subsequent calendar year during the Lease Term,
including any extensions or renewals thereof, Landlord shall present to Tenant a
statement of Tenant's Forecast Additional Rental for such calendar year;
provided, however, that if such statement is not given prior to the beginning of
any calendar year as aforesaid, Tenant shall continue to pay during the next
ensuing calendar year on the basis of the amount of Tenant's Forecast Additional
Rental payable during the calendar year just ended until the month after such
statement is delivered to Tenant.

                  (b) For purposes of this Lease, "Tenant's Additional Rental"
shall mean for each calendar year (or portion thereof) during the Lease Term
starting with calendar year 2000 the excess of (x) the Operating Expense Amount
(defined below) multiplied by the number of square feet of Rentable Floor Area
of the Premises, over (y) the Base Operating Expenses (defined below) multiplied
by the number of square feet of Rentable Floor Area of the Premises. As used
herein, "Operating Expense Amount" shall mean the amount of Operating Expenses
(as defined below) for such calendar year divided by the greater of (i)
ninety-five percent (95%) of the number of square feet of Rentable Floor Area of
the Building, or (ii) the total number of square feet of Rentable Floor Area
occupied in the Building for such calendar year on an average annualized basis;
provided, however, if the amount is calculated under (i) above, the Operating
Expenses actually incurred with respect to such calendar year shall be adjusted
to reflect the amount of Operating Expenses which would have been incurred if
the Building were ninety-five percent (95%) occupied throughout such calendar
year. As used herein, the term "Base Operating Expenses" shall mean the
Operating Expenses paid or incurred by Landlord in the Base Year (as hereinafter
defined) as if the Building was ninety-five percent (95%) occupied throughout
the Base Year, divided by ninety-five percent (95%) of the number of square feet
of Rentable Floor Area of the Building. If the Building was not ninety-five
percent (95%) occupied throughout the Base Year, then the Base Operating
Expenses shall be an amount which fairly reflects what the Operating Expenses
would have been in the Base Year had the Building been ninety-five percent (95%)
occupied throughout the Base Year, as determined by Landlord in its reasonable
opinion. As used herein, "Base Year" shall mean calendar year 1999.

                  (c) Within one hundred fifty (150) days after the end of
calendar year 2000 occurs and for each calendar year thereafter during the Lease
Term, or as soon thereafter as practicable, Landlord shall provide Tenant a
statement showing the Operating Expenses for said calendar year, as prepared by
an authorized representative of Landlord, and a statement prepared by Landlord
comparing Tenant's Forecast Additional Rental with Tenant's Additional Rental.
In the event Tenant's Forecast Additional Rental exceeds Tenant's Additional
Rental for said calendar year, Landlord shall credit such amount against the
Forecast Additional Rental next due hereunder or, if the Lease Term has expired
or is about to expire, refund such excess to Tenant within thirty (30) days of
such statement if Tenant is not in default under this Lease (in the instance of
a default, such excess shall be held as additional security for Tenant's
performance, may be applied by Landlord to cure any such default, and shall not
be refunded until any such default is cured). In the event that the Tenant's
Additional Rental exceeds Tenant's Forecast Additional Rental for said calendar
year, Tenant shall pay Landlord, within thirty (30) days of receipt of the
statement, an amount equal to such difference. The provisions of this Lease
concerning the payment of Tenant's Additional Rental shall survive the
expiration or earlier termination of this Lease.

                  (d) Provided Tenant is not in default hereunder, Landlord's
books and records pertaining to the calculation of Operating Expenses for any
calendar year within the Lease Term may be audited by Tenant or its
representatives at Landlord's office where Operating Expense records are kept,
at Tenant's expense, at any time within one hundred fifty (150) days after
Landlord's annual statement is delivered to Tenant for such calendar year;
provided that Tenant shall give Landlord not less than thirty (30) days' prior
written notice of any such audit. If Landlord's calculations of Tenant's
Additional Rental for the audited calendar year was incorrect, then Tenant shall
be entitled to a prompt refund of any overpayment or Tenant shall promptly pay
to Landlord the amount of any underpayment, as the case may be. In the event
that Landlord's calculation of Operating Expenses is in error in excess of five
percent (5%) of such amount, Landlord shall pay Tenant for the actual and
reasonable costs of Tenant's audit.

                                       3
<PAGE>
 
         9. Operating Expenses.

                  (a) For the purposes of this Lease, "Operating Expenses" shall
mean all expenses, costs and disbursements (but not specific costs billed to
specific tenants of the Building) of every kind and nature, computed on an
accrual basis, relating to or incurred or paid in connection with the ownership,
management, operation, repair and maintenance of the Project, including but not
limited to, the following:

                           (1) wages, salaries and other costs of all on-site
         and off-site employees engaged either full or part time in the
         operation, management, maintenance or access control of the Project,
         including taxes, insurance and benefits relating to such employees,
         allocated based upon the time such employees are engaged directly in
         providing such services;

                           (2) the cost of all supplies, tools, equipment and
         materials used in the operation, management, maintenance and access
         control of the Project;

                           (3) the cost of all utilities for the Project,
         including but not limited to the cost of electricity, gas, water, sewer
         services and power for lighting, air conditioning and ventilating;

                           (4) the cost of all maintenance and service
         agreements for the Project and the equipment therein, including, but
         not limited to, security service, garage operators, window cleaning,
         elevator maintenance, HVAC maintenance, janitorial service, landscaping
         maintenance and customary landscaping replacement;

                           (5) the cost of inspections, repairs and general
         maintenance of the Project;

                           (6) amortization (together with reasonable financing
         charges, whether or not actually incurred) of the cost of acquisition
         and/or installation of capital investment items (including security
         equipment), amortized over their respective useful lives, which are
         installed for the purpose of reducing operating expenses, promoting
         safety, complying with governmental requirements, or maintaining the
         first-class nature of the Project;

                           (7) the cost of casualty, rental loss, liability and
         other insurance applicable to the Project and Landlord's personal
         property used in connection therewith;

                           (8)  the cost of trash and garbage removal, vermin
         extermination, and snow, ice and debris removal;

                           (9) the cost of legal and accounting services
         incurred by Landlord in connection with the management, maintenance,
         operation and repair of the Project, excluding the owner's or
         Landlord's general accounting, such as partnership statements and tax
         returns, and excluding services described in Article 9(b)(14) below;

                           (10) all taxes, assessments and governmental charges,
         whether or not directly paid by Landlord, whether federal, state,
         county or municipal and whether they be by taxing districts or
         authorities presently taxing the Project or by others subsequently
         created or otherwise, and any other taxes and assessments attributable
         to the Project or its operation (and the costs of monitoring and
         contesting any of the same), including business license taxes and fees
         (all of the foregoing are herein sometimes collectively referred to as
         "Taxes"), excluding, however, taxes and assessments imposed on the
         personal property of the tenants of the Project, federal and state
         taxes on income, death taxes, franchise taxes, and any taxes (other
         than business license taxes and fees) imposed or measured on or by the
         income of Landlord from the operation of the Project; provided,
         however, that if at any time during the Lease Term, the present method
         of taxation or assessment shall be so changed that the whole or any
         part of the taxes, assessments, levies, impositions or charges now
         levied, assessed or imposed on real estate and the improvements thereon
         shall be discontinued and as a substitute therefor, or in lieu of or in
         addition thereto, taxes, assessments, levies, impositions or charges
         shall be levied, assessed and/or imposed wholly or partially as a
         capital levy or otherwise on the rents received from the Project or the
         rents reserved herein or any part thereof, then such substitute or
         additional taxes, assessments, levies, impositions or charges, to the
         extent so levied, assessed or imposed, shall be deemed to be included
         within the Operating Expenses to the extent that such substitute or
         additional tax would be payable if the Project were the only property
         of the Landlord subject to such tax; and it is agreed that Tenant will
         be responsible for ad valorem taxes on its personal property and on the
         value of the leasehold improvements in the Premises to the extent that
         the same exceed Building standard allowances, if said taxes are based
         upon an assessment which includes the cost of such leasehold
         improvements in excess of Building standard allowances (and if the
         taxing authorities do not separately assess Tenant's leasehold
         improvements, Landlord may make an appropriate allocation of the ad
         valorem taxes allocated to the Project to give effect to this
         sentence);

                           (11) the cost of operating the management office for
         the Project, including cost of office supplies, telephone expenses and
         non-capital investment equipment and amortization (together with
         reasonable financing charges) of the cost of capital investment
         equipment; and

                           (12) management fees not to exceed five percent (5%)
         of rents paid by tenants of the Building.

                                       4
<PAGE>
 
         (b) For purposes of this Lease, and notwithstanding anything in any
other provision of this Lease to the contrary, "Operating Expenses" shall not
include the following:

                           (1) the cost of any special work or service performed
         for any tenant (including Tenant) at such tenant's cost;

                           (2) the cost of installing, operating and maintaining
         any specialty service, such as an observatory, broadcasting facility,
         luncheon club, restaurant, cafeteria, retail store, sundry shop,
         newsstand, or concession, but only to the extent such costs exceed
         those which would normally be expected to be incurred had such space
         been general office space;

                           (3) the cost of correcting defects in construction;

                           (4) compensation paid to officers and executives of
         Landlord (but it is understood that the on-site Building manager and
         other on-site employees below the grade of Building manager may carry a
         title such as vice president and the salaries and related benefits of
         these officers/employees of Landlord would be allowable Operating
         Expenses under Article 9[a][1] above);

                           (5) the cost of any items for which Landlord is
         reimbursed by insurance, condemnation or otherwise, except for costs
         reimbursed pursuant to provisions similar to Articles 7 and 9 hereof.

                           (6) the cost of any additions, changes, replacements
         and other items which are made in order to prepare for a new tenant's
         occupancy;

                           (7) the cost of repairs incurred by reason of fire or
         other casualty;

                           (8) insurance premiums to the extent Landlord may be
         directly reimbursed therefor, except for premiums reimbursed pursuant
         to provisions similar to Articles 7 and 9 hereof;

                           (9) interest on debt or amortization payments on any
         mortgage or deed to secure debt (except to the extent specifically
         permitted by Article 9[a]) and rental under any ground lease or other
         underlying lease;

                           (10) any real estate brokerage commissions or other
         costs incurred in procuring tenants or any fee in lieu of such
         commission;

                           (11) any advertising expenses incurred in connection
         with the marketing of any rentable space;

                           (12) rental payments for base Building equipment such
         as HVAC equipment and elevators;

                           (13) any expenses for repairs or maintenance which
         are covered by warranties and service contracts, to the extent such
         maintenance and repairs are made at no cost to Landlord;

                           (14) legal expenses arising out of the construction
         of the improvements on the Land or the enforcement of the provisions of
         any lease affecting the Land or Building, including without limitation
         this Lease;

                           (15) Costs of capital improvements except as set
         forth in paragraph 9(a)(6) above;

                           (16) Salaries or fringe benefits or personnel above
         the grade of Building Manager;

                           (17) The cost of any items to the extent to which
         such cost is reimbursed or reimbursable to Landlord by tenants of the
         Building (other than by virtue of the pass through of "Operating
         Expenses" to other tenants of the Building);

                           (18) Advertising and promotional expenses incurred in
         connection with the leasing of the Building;

                           (19) Costs incurred in connection with making repairs
         which are the obligation of another tenant of the Building.

                           (20) Costs incurred by Landlord as a result of
         Landlord's breach of this Lease or any other lease with a tenant of the
         Building; and

                           (21) Costs associated with the removal or
         encapsulation of asbestos or asbestos-containing materials or the
         management, removal or remediation of any Hazardous Substances.

         10. Tenant Taxes. Tenant shall pay promptly when due all taxes directly
or indirectly imposed or assessed upon Tenant's gross sales, business
operations, machinery, equipment, trade fixtures and other personal property or
assets, whether such taxes are assessed against Tenant, Landlord or the
Building. In the event that such taxes are imposed or assessed against Landlord
or the Building, Landlord shall furnish Tenant with all applicable tax bills,
public charges and other assessments or impositions and Tenant shall forthwith
pay the same either directly to the taxing authority or, at Landlord's option,
to Landlord.

                                       5
<PAGE>
 
         11. Payments. All payments of Rent and other payments to be made to
Landlord shall be made on a timely basis and shall be payable to Landlord or as
Landlord may otherwise designate. All such payments shall be mailed or delivered
to Landlord's Address designated in Article 1(b) above or at such other place as
Landlord may designate from time to time in writing. If mailed, all payments
shall be mailed in sufficient time and with adequate postage thereon to be
received in Landlord's account by no later than the due date for such payment.
Tenant agrees to pay to Landlord Fifty Dollars ($50.00) for each check presented
to Landlord in payment of any obligation of Tenant which is not paid by the bank
on which it is drawn, together with interest from and after the due date for
such payment at the rate of eighteen percent (18%) per annum on the amount due.

         12. Late Charges. Any Rent or other amounts payable to Landlord under
this Lease, if not paid by the fifth day of the month for which such Rent is
due, or by the due date specified on any invoices from Landlord for any other
amounts payable hereunder, shall incur a late charge of Fifty Dollars ($50.00)
for Landlord's administrative expense in processing such delinquent payment and
in addition thereto shall bear interest at the rate of eighteen percent (18%)
per annum from and after the due date for such payment. Notwithstanding anything
to the contrary contained in this Lease, in no event shall the rate of interest
payable on any amount due under this Lease exceed the legal limits for such
interest enforceable under applicable law.

         13. Uses. The Premises may be used for a 24-hour telecommunications
switch facility executive, general administrative and office space purposes and
no other purposes and in accordance with all applicable laws, ordinances, rules
and regulations of governmental authorities and the Rules and Regulations
attached hereto and made a part hereof. Tenant shall have twenty-four (24) hours
a day, seven (7) days a week access to the Premises subject to reasonable
security procedures implemented by Landlord. Tenant covenants and agrees that it
will, at its expense, comply with all laws, ordinances, orders, directions,
requirements, rules and regulations of all governmental authorities (including
Federal, State, county and municipal authorities), now in force or which may
hereafter be in force, which shall impose any duty upon Landlord or Tenant with
respect to the use, occupancy or alteration (made by Tenant) of the Premises,
and of all insurance bodies applicable to the Premises or to the Tenant's use or
occupancy thereof. Tenant covenants and agrees to abide by the Rules and
Regulations in all respects as now set forth and attached hereto or as hereafter
promulgated by Landlord. Landlord shall have the right at all times during the
Lease Term to publish and promulgate and thereafter enforce such rules and
regulations or changes in the existing Rules and Regulations as it may
reasonably deem necessary in its sole discretion to protect the tenantability,
safety, operation, and welfare of the Premises and the Project. Tenant
acknowledges that portions of the Building (currently consisting of portions of
Showroom Levels 1 and 2) may be used as a technology mart and that the tenants
on the technology mart floors of the Building may have showrooms used for the
display of such tenants' technology products and services. In addition, the
conference, meeting, exhibition, atrium lobby and theater facilities of the
Building may also be used for meetings and expositions. Tenant does hereby
acknowledge that it has been fully informed of this intended use of the Building
and that Tenant will not contend that any such use of the Building violates any
terms or provisions of this Lease or diminishes Tenant's obligations hereunder
in any way whatsoever.

         14. Alterations. Except for any initial improvement of the Premises
pursuant to Exhibit "D", which shall be governed by the provisions of said
Exhibit "D", Tenant shall not make, suffer or permit to be made any alterations,
additions or improvements to or of the Premises or any part thereof, or attach
any fixtures thereto except for Tenant's trade fixtures and equipment, without
first obtaining Landlord's written consent. With respect to any alteration,
addition or improvement which does not affect the structure of the Building,
does not affect any of the Building's systems (e.g., mechanical, electrical or
plumbing), does not diminish the capacity of such Building systems available to
other portions of the Building, is not visible from the common areas or exterior
of the Building, and is in full compliance with all laws, orders, ordinances,
directions, requirements, rules and regulations of all governmental authorities,
Landlord's consent shall not be unreasonably withheld. Any such alterations,
additions or improvements to the Premises consented to by Landlord shall be made
by Landlord or under Landlord's supervision for Tenant's account and Tenant
shall reimburse Landlord for all costs thereof (including a reasonable charge
for Landlord's overhead), as Rent, within thirty (30) days after receipt of a
statement. All such alterations, additions and improvements shall become
Landlord's property at the expiration or earlier termination of the Lease Term
and shall remain on the Premises without compensation to Tenant unless Landlord
elects by notice to Tenant at the time Landlord grants its approval to have
Tenant remove such alterations, additions and improvements, in which event,
notwithstanding any contrary provisions respecting such alterations, additions
and improvements contained in Article 32 hereof, Tenant shall promptly restore,
at its sole cost and expense, the Premises to its condition prior to the
installation of such alterations, additions and improvements, normal wear and
tear excepted.

         15. Repairs.

                  (a) Landlord shall maintain in good order and repair, subject
to normal wear and tear and subject to casualty and condemnation, the Building
(excluding the Premises and other portions of the Building leased to other
tenants), the Building parking facilities, the public areas and the landscaped
areas. Notwithstanding the foregoing obligation, the cost of any repairs or
maintenance to the foregoing necessitated by the intentional acts or negligence
of Tenant or its agents, contractors, employees, invitees, licensees, tenants or
assigns, shall be borne solely by Tenant and shall be deemed Rent hereunder and
shall be reimbursed by Tenant to Landlord upon demand. Landlord shall not be
required to make any repairs or improvements to the Premises except structural
repairs.

                  (b) Tenant covenants and agrees that it will take good care of
the Premises and all alterations, additions and improvements thereto and will
keep and maintain the same in good condition and repair, except for normal wear
and tear. Tenant shall at once report, in writing, to Landlord any defective or
dangerous condition known to Tenant. To the fullest extent permitted by law,
Tenant hereby waives all rights to make repairs at the expense of Landlord or in
lieu thereof to vacate the Premises as may be provided by any law, statute or
ordinance now or hereafter in effect. Landlord has no obligation and has made no
promise to alter, remodel, improve, repair, decorate or paint the Premises or
any part thereof, except as specifically and expressly herein set forth.

                                       6
<PAGE>
 
         16. Landlord's Right of Entry. Landlord shall retain duplicate keys to
all doors of the Premises and Landlord and its agents, employees and independent
contractors shall have the right to enter the Premises at reasonable hours to
inspect and examine same, to make repairs, additions, alterations and
improvements, to exhibit the Premises to mortgagees, prospective mortgagees,
purchasers or tenants, and to inspect the Premises to ascertain that Tenant is
complying with all of its covenants and obligations hereunder, all without being
liable to Tenant in any manner whatsoever for any damages arising therefrom;
provided, however, that (a) Landlord shall, except in case of emergency, afford
Tenant such prior notification of an entry into the Premises as shall be
reasonably practicable under the circumstances, and (b) Landlord will not enter
(or provide entrance) to Tenant's designated high security areas except in case
of an emergency. Landlord shall be allowed to take into and through the Premises
any and all materials that may be required to make such repairs. During such
time as such work is being carried on, in or about the Premises, the Rent
provided herein shall not abate, and Tenant waives any claim or cause of action
against Landlord for damages by reason of interruption of Tenant's business or
loss of profits therefrom because of the prosecution of any such work or any
part thereof. Notwithstanding the foregoing, Landlord shall use its best efforts
not to interfere with Tenant's business or use of the Premises.

         17. Insurance. Tenant shall procure at its expense and maintain
throughout the Lease Term a policy or policies of commercial property insurance,
issued on an "all risks" basis insuring the full replacement cost of its
furniture, equipment, supplies and other property owned, leased, held or
possessed by it and contained in the Premises, together with the excess value of
the improvements to the Premises over the Tenant Improvement Allowance (with a
replacement cost endorsement sufficient to prevent Tenant from becoming a
co-insurer), and workmen's compensation insurance as required by applicable law.
Tenant shall also procure at its expense and maintain throughout the Lease Term
a policy or policies of commercial general liability insurance, written on an
occurrence basis and insuring Tenant, Landlord and any other person designated
by Landlord, against any and all liability for injury to or death of a person or
persons and for damage to property occasioned by or arising out of any
construction work being done on the Premises, or arising out of the condition,
use or occupancy of the Premises, or in any way occasioned by or arising out of
the activities of Tenant, its agents, contractors, employees, guests or
licensees in the Premises, or other portions of the Building or the Project, the
limits of such policy or policies to be in combined single limits for both
damage to property and personal injury and in amounts not less than Three
Million Dollars ($3,000,000.00) for each occurrence. Such insurance shall, in
addition, extend to any liability of Tenant arising out of the indemnities
provided for in this Lease , together with business interruption insurance which
is designed to afford Tenant protection up to a maximum amount of coverage which
Tenant in its reasonable discretion shall determine to be satisfactory to Tenant
in the event the Premises for any reason become unusable or for any other reason
covered by such policy Tenant's operation its business is interrupted. All
insurance policies procured and maintained by Tenant pursuant to this Article 17
shall name Landlord and any additional parties designated by Landlord as
additional insured, shall be carried with companies licensed to do business in
the State of Georgia reasonably satisfactory to Landlord and shall be
non-cancelable and not subject to material change except after twenty (20) days'
written notice to Landlord. Such policies or duly executed certificates of
insurance with respect thereto, accompanied by proof of payment of the premium
therefor, shall be delivered to Landlord prior to the Rental Commencement Date,
and renewals of such policies shall be delivered to Landlord at least thirty
(30) days prior to the expiration of each respective policy term.

         18. Waiver of Subrogation. Landlord and Tenant shall each have included
in all policies of commercial property insurance, commercial general liability
insurance, and business interruption and other insurance respectively obtained
by them covering the Premises, the Building and contents therein, a waiver by
the insurer of all right of subrogation against the other in connection with any
loss or damage thereby insured against. Any additional premium for such waiver
shall be paid by the primary insured. To the full extent permitted by law,
Landlord and Tenant each waives all right of recovery against the other for, and
agrees to release the other from liability for, loss or damage to the extent
such loss or damage is covered by valid and collectible insurance in effect at
the time of such loss or damage or, in the event of self-insurance or a failure
to insure, would be covered by the insurance required to be maintained under
this Lease by the party seeking recovery.

         19. Default.

                  (a) The following events shall be deemed to be events of
default by Tenant under this Lease: (i) Tenant shall fail to pay any installment
of Rent or any other charge or assessment against Tenant pursuant to the terms
hereof and such failure shall continue for five (5) days after written notice of
such failure of payment; provided, however, such notice and such grace period
shall be required to be provided by Landlord and shall be accorded Tenant, if
necessary, only two (2) times during any calendar year of the Lease Term, and an
event of default shall be deemed to have immediately occurred upon the third
(3rd) failure by Tenant to make a timely payment aforesaid within any calendar
year of the Lease Term; (ii) Tenant shall fail to comply with any term,
provision, covenant or warranty made under this Lease by Tenant, other than the
payment of the Rent or any other charge or assessment payable by Tenant, and
shall not cure such failure within thirty (30) days after notice thereof to
Tenant (provided, however, if such default is not capable of being cured within
such period, Tenant shall not be in default hereunder if Tenant commences to
cure such default and diligently proceeds to cure such default with such
period); (iii) Tenant or any guarantor of this Lease shall make a general
assignment for the benefit of creditors, or shall admit in writing its inability
to pay its debts as they become due, or shall file a petition in bankruptcy, or
shall be adjudicated as bankrupt or insolvent, or shall file a petition in any
proceeding seeking any reorganization, arrangement, composition, readjustment,
liquidation, dissolution or similar relief under any present or future statute,
law or regulation, or shall file an answer admitting or fail timely to contest
the material allegations of a petition filed against it in any such proceeding;
(iv) a proceeding is commenced against Tenant or any guarantor of this Lease
seeking any reorganization, arrangement, composition, readjustment, liquidation,
dissolution or similar relief under any present or future statute, law or
regulation, and such proceeding shall not have been dismissed within sixty (60)
days after the commencement thereof; (v) a receiver or trustee shall be
appointed for the Premises or for all or substantially all of the assets of
Tenant or of any guarantor of this Lease; (vi) Tenant shall abandon or vacate
all or any portion of the Premises or fail to take possession thereof as
provided in this Lease; (vii) Tenant shall do or permit to be done anything
which creates a lien upon the Premises or the Project and such lien is not
removed or discharged or bonded over within fifteen (15) days after the filing
thereof; (viii) Tenant shall fail to return a properly executed instrument to
Landlord in accordance with the provisions of

                                       7
<PAGE>
 
Article 27 hereof within the time period provided for such return following
Landlord's request for same as provided in Article 27 and after five (5) days
notice to Tenant; or (ix) Tenant shall fail to return a properly executed
estoppel certificate to Landlord in accordance with the provisions of Article 28
hereof within the time period provided for such return following Landlord's
request for same as provided in Article 28 and after five (5) days notice to
Tenant.

                  (b) Upon the occurrence of any of the aforesaid events of
default, Landlord shall have the option to pursue any one or more of the
following remedies without any notice or demand whatsoever: (i) terminate this
Lease, in which event Tenant shall immediately surrender the Premises to
Landlord and if Tenant fails to do so, Landlord may without prejudice to any
other remedy which it may have for possession or arrearages in Rent, enter upon
and take possession of the Premises and expel or remove Tenant and any other
person who may be occupying the Premises or any part thereof, by force, if
necessary, without being liable for prosecution or any claim of damages
therefor; Tenant hereby agreeing to pay to Landlord on demand the amount of all
loss and damage which Landlord may suffer by reason of such termination, whether
through inability to relet the Premises on satisfactory terms or otherwise; (ii)
terminate Tenant's right of possession (but not this Lease) and enter upon and
take possession of the Premises and expel or remove Tenant and any other person
who may be occupying the Premises or any part thereof, by entry (including the
use of force, if necessary), dispossessory suit or otherwise, without thereby
releasing Tenant from any liability hereunder, without terminating this Lease,
and without being liable for prosecution or any claim of damages therefor and,
if Landlord so elects, make such alterations, redecorations and repairs as, in
Landlord's judgment, may be necessary to relet the Premises, and Landlord may,
but shall be under no obligation to do so, relet the Premises or any portion
thereof in Landlord's or Tenant's name, but for the account of Tenant, for such
term or terms (which may be for a term extending beyond the Lease Term) and at
such rental or rentals and upon such other terms as Landlord may deem advisable,
with or without advertisement, and by private negotiations, and receive the rent
therefor, Tenant hereby agreeing to pay to Landlord the deficiency, if any,
between all Rent reserved hereunder and the total rental applicable to the Lease
Term hereof obtained by Landlord re-letting, and Tenant shall be liable for
Landlord's expenses in redecorating and restoring the Premises and all costs
incident to such re-letting, including broker's commissions and lease
assumptions, and in no event shall Tenant be entitled to any rentals received by
Landlord in excess of the amounts due by Tenant hereunder; or (iii) enter upon
the Premises by force, if necessary, without being liable for prosecution or any
claim of damages therefor, and do whatever Tenant is obligated to do under the
terms of this Lease; and Tenant agrees to reimburse Landlord on demand for any
expenses including, without limitation, reasonable attorneys' fees which
Landlord may incur in thus effecting compliance with Tenant's obligations under
this Lease and Tenant further agrees that Landlord shall not be liable for any
damages resulting to Tenant from such action, whether caused by negligence of
Landlord or otherwise. If this Lease is terminated by Landlord as a result of
the occurrence of an event of default, Landlord may declare due and payable
immediately an amount determined as follows: (x) the entire amount of Rent and
other charges and assessments which would have become due and payable during the
remainder of the Lease Term (including, without limitation, increases in Rent
pursuant to Article 8 hereof), discounted to present value by using a discount
factor of eight percent (8%) per annum, plus (y) all of Landlord's costs and
expenses (including, without limitation, Landlord's expenses in redecorating and
restoring the Premises and all costs relating to such reletting, including
broker's commissions and lease assumptions) reasonably incurred in connection
with or related to the reletting of the Premises, minus (z) the market rental
value of the Premises for the remainder of the Lease Term, discounted to present
value by using a discount factor of eight percent (8%) per annum. Such payment
shall not constitute a penalty or forfeiture but shall constitute liquidated
damages for Tenant's failure to comply with the terms and provisions of this
Lease (Landlord and Tenant agreeing that Landlord's exact damages in such event
are impossible to ascertain and that the amount set forth above is a reasonable
estimate thereof). For purposes of determining what could be collected by
Landlord by reletting under this subsection, Landlord is not required to relet
when other comparable space in the Building is available. The term "remaining
Lease Term" as used in this subsection shall mean the period which otherwise
would have (but for the termination of this Lease) constituted the balance of
the Lease Term from the date of the termination of this Lease.

                  (c) Pursuit of any of the foregoing remedies shall not
preclude pursuit of any other remedy herein provided or any other remedy
provided by law or at equity, nor shall pursuit of any remedy herein provided
constitute an election of remedies thereby excluding the later election of an
alternate remedy, or a forfeiture or waiver of any Rent or other charges and
assessments payable by Tenant and due to Landlord hereunder or of any damages
accruing to Landlord by reason of violation of any of the terms, covenants,
warranties and provisions herein contained. No reentry or taking possession of
the Premises by Landlord or any other action taken by or on behalf of Landlord
shall be construed to be an acceptance of a surrender of this Lease or an
election by Landlord to terminate this Lease unless written notice of such
intention is given to Tenant. Forbearance by Landlord to enforce one or more of
the remedies herein provided upon an event of default shall not be deemed or
construed to constitute a waiver of such default. In determining the amount of
loss or damage which Landlord may suffer by reason of termination of this Lease
or the deficiency arising by reason of any reletting of the Premises by Landlord
as above provided, allowance shall be made for the expense of repossession.
Tenant agrees to pay to Landlord all costs and expenses incurred by Landlord in
the enforcement of this Lease, including without limitation, the fees of
Landlord's attorneys as provided in Article 25 hereof.

         20. Waiver of Breach. No waiver of any breach of the covenants,
warranties, agreements, provisions, or conditions contained in this Lease shall
be construed as a waiver of said covenant, warranty, provision, agreement or
condition or of any subsequent breach thereof, and if any breach shall occur and
afterwards be compromised, settled or adjusted, this Lease shall continue in
full force and effect as if no breach had occurred.

         21. Assignment and Subletting. Tenant shall not, without the prior
written consent of Landlord, assign this Lease or any interest herein or in the
Premises, or mortgage, pledge, encumber, hypothecate or otherwise transfer or
sublet the Premises or any part thereof or permit the use of the Premises by any
party other than Tenant. Consent to one or more such transfers or subleases
shall not destroy or waive this provision, and all subsequent transfers and
subleases shall likewise be made only upon obtaining the prior written consent
of Landlord. Without limiting the foregoing prohibition, in no event shall
Tenant assign this Lease or any interest herein, whether directly, indirectly or
by operation of law, or sublet the Premises or any part thereof or permit the
use of the Premises or any part thereof by any party if such proposed

                                       8
<PAGE>
 
assignment, subletting or use would contravene any restrictive covenant
(including any exclusive use) granted to any other tenant of the Building or
would contravene the provisions of Article 13 of this Lease. Sublessees or
transferees of the Premises for the balance of the Lease Term shall become
directly liable to Landlord for all obligations of Tenant hereunder, without
relieving Tenant (or any guarantor of Tenant's obligations hereunder) of any
liability therefor, and Tenant shall remain obligated for all liability to
Landlord arising under this Lease during the entire remaining Lease Term
including any extensions thereof, whether or not authorized herein. If Tenant is
a partnership, a withdrawal or change, whether voluntary, involuntary or by
operation of law, of partners owning a controlling interest in the Tenant shall
be deemed a voluntary assignment of this Lease and subject to the foregoing
provisions. If Tenant is a corporation, any dissolution, merger, consolidation
or other reorganization of Tenant, or the sale or transfer of a controlling
interest in the capital stock of Tenant, whether in a single transaction or in a
series of transactions, shall be deemed a voluntary assignment of this Lease and
subject to the foregoing provisions. Landlord may, as a prior condition to
considering any request for consent to an assignment or sublease, require Tenant
to obtain and submit current financial statements of any proposed subtenant or
assignee and such other financial documentation relative to the proposed
subtenant or assignee as Landlord may reasonably require. In the event Landlord
consents to an assignment or sublease, Tenant shall pay to Landlord a fee to
cover Landlord's reasonable accounting costs plus any legal fees incurred by
Landlord as a result of the assignment or sublease. The consent of Landlord to
any proposed assignment or sublease may be withheld by Landlord in its sole and
absolute discretion, and in no event will Landlord be required to agree to any
subleasing of all or part of the Premises or any assignment of any rights of
Tenant under this Lease to any other tenant of the Building. Landlord may
require an additional security deposit from the assignee or subtenant as a
condition of its consent. Any consideration, in excess of the Rent and expenses
of Tenant and other charges and sums due and payable by Tenant under this Lease,
paid to Tenant by any assignee of this Lease for its assignment, or by any
sublessee under or in connection with its sublease, or otherwise paid to Tenant
by another party for use and occupancy of the Premises or any portion thereof,
shall be promptly remitted by Tenant to Landlord as additional rent hereunder
and Tenant shall have no right or claim thereto as against Landlord. No
assignment of this Lease consented to by Landlord shall be effective unless and
until Landlord shall receive an original assignment and assumption agreement, in
form and substance satisfactory to Landlord, signed by Tenant and Tenant's
proposed assignee, whereby the assignee assumes due performance of this Lease to
be done and performed for the balance of the then remaining Lease Term of this
Lease. No subletting of the Premises, or any part thereof, shall be effective
unless and until there shall have been delivered to Landlord an agreement, in
form and substance satisfactory to Landlord, signed by Tenant and the proposed
sublessee, whereby the sublessee acknowledges the right of Landlord to continue
or terminate any sublease, in Landlord's sole discretion, upon termination of
this Lease, and such sublessee agrees to recognize and attorn to Landlord in the
event that Landlord elects under such circumstances to continue such sublease.
Upon Landlord's receipt of a request by Tenant to assign this Lease or any
interest herein or in the Premises or to transfer or sublet the Premises or any
part thereof or permit the use of the Premises by any party other than Tenant,
Landlord shall have the right, at Landlord's option, to exercise in writing any
of the following options: (a) To terminate this Lease as to the portion of the
Premises proposed to be assigned or sublet; (b) to consent to the proposed
assignment or sublease, subject to the other terms and conditions set forth in
this Article 21; or (c) to refuse to consent to the proposed assignment or
sublease, which refusal shall be deemed to have been exercised unless Landlord
gives Tenant written notice providing otherwise within ten (10) days of Tenant's
request to sublease or assign.

         Notwithstanding the foregoing, in no event shall any co-location of any
portion of the Premises be considered a sublease or assignment.

         22. Destruction.

                  (a) If the Premises are damaged by fire or other casualty, the
same shall be repaired or rebuilt as speedily as practical under the
circumstances at the expense of Landlord, unless this Lease is terminated as
provided in this Article 22, and during the period required for restoration, a
just and proportionate part of Base Rental shall be abated until the Premises
are repaired or rebuilt.

                  (b) If the Premises are (i) damaged to such an extent that
repairs cannot, in Landlord's reasonable judgment, be completed within one
hundred eighty (180) days after the date of the casualty, or (ii) damaged or
destroyed as a result of a risk which is not insured under the insurance
policies required hereunder, or (iii) damaged or destroyed during the last
eighteen (18) months of the Lease Term, or (iv) if the Building is damaged in
whole or in part (whether or not the Premises are damaged) to such an extent
that the Building cannot, in Landlord's reasonable judgment, be operated
economically as an integral unit, then and in any such event Landlord may at its
option terminate this Lease by notice in writing to Tenant within sixty (60)
days after the day of such occurrence. If the Premises are damaged to such an
extent that repairs cannot, in Landlord's reasonable judgment, be completed
within one hundred eighty (180) days after the date of the casualty or if the
Premises are substantially damaged during the last eighteen (18) months of the
Lease Term, then in either such event Tenant may elect to terminate this Lease
by notice in writing to Landlord within sixty (60) days after the date of such
occurrence. Unless Landlord or Tenant elects to terminate this Lease as
hereinabove provided, this Lease will remain in full force and effect and
Landlord shall repair such damage at its expense to the extent required under
subparagraph (c) below as expeditiously as possible under the circumstances.

                  (c) If Landlord should elect or be obligated pursuant to
subparagraph (a) above to repair or rebuild because of any damage or
destruction, Landlord's obligation shall be limited to the original Building and
any other work or improvements which were originally performed or installed at
Landlord's expense as described in Exhibit "D" hereto or with the proceeds of
the Tenant Improvement Allowance. If the cost of performing such repairs exceeds
the actual proceeds of insurance paid or payable to Landlord on account of such
casualty, or if Landlord's mortgagee or the lessor under a ground or underlying
lease shall require that any insurance proceeds from a casualty loss be paid to
it, Landlord may terminate this Lease unless Tenant, within fifteen (15) days
after demand therefor, deposits with Landlord a sum of money sufficient to pay
the difference between the cost of repair and the proceeds of the insurance
available to Landlord for such purpose.

                  (d) In no event shall Landlord be liable for any loss or
damage sustained by Tenant by reason of casualties mentioned

                                       9
<PAGE>
 
hereinabove or any other accidental casualty.

         23. Landlord's Lien. [INTENTIONALLY DELETED].

         24. Services by Landlord. Landlord shall provide the Building Standard
Services described on Exhibit "E" attached hereto and by this reference made a
part hereof.

         25. Attorneys' Fees and Homestead. If any Rent or other debt owing by
Tenant to Landlord hereunder is collected by or through an attorney-at-law,
Tenant agrees to pay any reasonable attorney's fees actually incurred by
Landlord. If Landlord uses the services of any attorney in order to secure
compliance with any other provisions of this Lease, to recover damages for any
breach or default of any other provisions of this Lease, or to terminate this
Lease or evict Tenant, and Landlord prevails in such action, Tenant shall
reimburse Landlord upon demand for any and all attorneys' fees and expenses so
incurred by Landlord. If Tenant uses the services of any attorney in order to
secure Landlord's compliance with any provisions of this Lease, to recover
damages for any breach or default by Landlord of any other provisions of this
Lease, and Tenant prevails in such action, Landlord shall reimburse Tenant upon
demand for any and all attorney's fees and expenses so incurred by Tenant.
Tenant waives all homestead rights and exemptions which it may have under any
law as against any obligation owing under this Lease, and assigns to Landlord
its homestead and exemptions to the extent necessary to secure payment and
performance of its covenants and agreements hereunder.

         26. Time. Time is of the essence of this Lease and whenever a certain
day is stated for payment or performance of any obligation of Tenant or
Landlord, the same enters into and becomes a part of the consideration hereof.

         27. Subordination and Attornment.

                  (a) Landlord represents and warrants to Tenant that the
Project, and each component thereof, is not, and at the Commencement Date will
not be, subject to or encumbered by any deed to secure debt, mortgage or other
similar security instrument. Tenant agrees on and subject to the terms and
conditions of this Article 27, to subordinate its interest hereunder to, and to
attorn to the holder of, any mortgage hereafter encumbering the Premises or the
Project or any component thereof, to all advances hereafter to be made upon the
security of such mortgage, to all amendments, modifications, renewals,
consolidations, extensions and restatements of such mortgage, and to any
replacements and substitutions for such mortgage, provided that Landlord
provides Tenant with a fully executed Subordination, Non-Disturbance and
Attornment Agreement in substantially the same form as Exhibit "H" attached
hereto from any ground lessors or mortgage holders of Landlord who later come
into existence with respect to the Project, or any component thereof, at any
time prior to the expiration of the Term (or any renewal) of the Lease in
consideration of, and as a condition precedent to, Tenant's agreement under this
Article 27.

                  (b) If any mortgagee elects to have this Lease superior to its
mortgage and signifies its election in the instrument creating its lien or lease
or by separate recorded instrument, then this Lease shall be superior to such
mortgage, as the case may be. The term "mortgage", as used in this Lease,
includes any deed to secure debt, deed of trust or security deed and any other
instrument creating a lien in connection with any other method of financing or
refinancing. The term "mortgagee", as used in this Lease, refers to the
holder(s) of the indebtedness secured by a mortgage.

         28. Estoppel Certificates. Within ten (10) days after request therefor
by Landlord, Tenant agrees to execute and deliver to Landlord in recordable form
an estoppel certificate addressed to Landlord, any mortgagee or assignee of
Landlord's interest in, or purchaser of, the Premises or the Building or any
part thereof, certifying (if such be the case) that this Lease is unmodified and
is in full force and effect (and if there have been modifications, that the same
is in full force and effect as modified and stating said modifications); that
there are no defenses or offsets against the enforcement thereof or stating
those claimed by Tenant; and stating the date to which Rent and other charges
have been paid. Such certificate shall also include such other information as
may reasonably be required by such mortgagee, proposed mortgagee, assignee,
purchaser or Landlord. Any such certificate may be relied upon by Landlord, any
mortgagee, proposed mortgagee, assignee, purchaser and any other party to whom
such certificate is addressed.

         29. No Estate. This Lease shall create the relationship of landlord and
tenant only between Landlord and Tenant and no estate shall pass out of
Landlord. Tenant shall have only an usufruct, not subject to levy and sale and
not assignable in whole or in part by Tenant except as herein provided.

         30. Cumulative Rights. All rights, powers and privileges conferred
hereunder upon the parties hereto shall be cumulative to, but not restrictive
of, or in lieu of those conferred by law.

         31. Holding Over. If Tenant remains in possession after expiration or
termination of the Lease Term with or without Landlord's written consent, Tenant
shall become a tenant-at-sufferance, and there shall be no renewal of this Lease
by operation of law. During the period of any such holding over, all provisions
of this Lease shall be and remain in effect except that the monthly rental shall
be one hundred fifty percent (150%) of the amount of Rent (including any
adjustments as provided herein) payable for the last full calendar month of the
Lease Term including renewals or extensions. The inclusion of the preceding
sentence in this Lease shall not be construed as Landlord's consent for Tenant
to hold over.

         32. Surrender of Premises. Upon the expiration or other termination of
this Lease, Tenant shall quit and surrender to Landlord the Premises and every
part thereof and all alterations, additions and improvements thereto, broom
clean and in good condition and state of repair,

                                       10
<PAGE>
 
reasonable wear and tear only excepted. If Tenant is not then in default, Tenant
shall remove all personalty and equipment not attached to the Premises and all
trade fixtures which it has placed upon the Premises, and Tenant shall repair
any damage to the Premises caused by such removal. If Tenant shall fail or
refuse to remove all of Tenant's effects, personalty and equipment from the
Premises upon the expiration or termination of this Lease for any cause
whatsoever or upon Tenant being dispossessed by process of law or otherwise,
such effects, personalty and equipment shall be deemed conclusively to be
abandoned after five (5) days written notice from Landlord and may be
appropriated, sold, stored, destroyed or otherwise disposed of by Landlord
without written notice to Tenant or any other party and without obligation to
account for them. Tenant shall pay Landlord on demand any and all expenses
incurred by Landlord in the removal of such property, including, without
limitation, the cost of repairing any damage to the Building or Project caused
by the removal of such property and storage charges (if Landlord elects to store
such property). The covenants and conditions of this Article 32 shall survive
any expiration or termination of this Lease.

         33. Notices. All notices required or permitted to be given hereunder
shall be in writing and shall be sent by certified mail, return receipt
requested, in which case the same shall be deemed delivered three (3) business
days after deposit, postage prepaid in the U.S. Mail, (ii) sent by overnight
delivery using a nationally recognized overnight courier, in which case the same
shall be deemed delivered one (1) business day after deposit with such courier,
(iii) delivered personally; or (iv) sent by electronic transfer or facsimile, in
which case the same shall be deemed delivered on the date of the electronic
answerback receipt confirmation and followed by a delivery described in (ii) or
(iii) above. The above addresses of a party may be changed by such party by
written notice to the other party; provided, however, that no notice of a change
of address shall be effective until actual receipt of such notice.

         34. Damage or Theft of Personal Property. All personal property brought
into the Premises by Tenant, or Tenant's employees, agents, or business
visitors, shall be at the risk of Tenant only, and Landlord shall not be liable
for theft thereof or any damage thereto occasioned by any act of co-tenants,
occupants, invitees or other users of the Building or any other person. Landlord
shall not at any time be liable for damage to any property in or upon the
Premises, which results from gas, smoke, water, rain, ice or snow which issues
or leaks from or forms upon any part of the Building or from the pipes or
plumbing work of the same, or from any other place whatsoever except to the
extent caused by the negligence or willful misconduct of Landlord.

         35. Eminent Domain.

                  (a) If all or part of the Premises shall be taken for any
public or quasi-public use by virtue of the exercise of the power of eminent
domain or by private purchase in lieu thereof, this Lease shall terminate as to
the part so taken as of the date of taking, and, in the case of a partial
taking, either Landlord or Tenant shall have the right to terminate this Lease
as to the balance of the Premises by written notice to the other within thirty
(30) days after such date; provided, however, that a condition to the exercise
by Tenant of such right to terminate shall be that the portion of the Premises
taken shall be of such extent and nature as substantially to handicap, impede or
impair Tenant's use of the balance of the Premises. If title to so much of the
Project is taken that a reasonable amount of reconstruction thereof will not in
Landlord's sole reasonable discretion result in the Building being a practical
improvement and reasonably suitable for use for the purpose for which it is
designed, then this Lease shall terminate on the date that the condemning
authority actually takes possession of the part so condemned or purchased.

                  (b) If this Lease is terminated under the provisions of this
Article 35, Rent shall be apportioned and adjusted as of the date of
termination. Tenant shall have no claim against Landlord or against the
condemning authority for the value of any leasehold estate or for the value of
the unexpired Lease Term provided that the foregoing shall not preclude any
claim that Tenant may have against the condemning authority for the unamortized
cost of leasehold improvements, to the extent the same were installed at
Tenant's expense (and not with the proceeds of the Tenant Improvement
Allowance), or for loss of business, moving expenses or other consequential
damages, in accordance with subparagraph (d) below.

                  (c) If there is a partial taking of the Project and this Lease
is not thereupon terminated under the provisions of this Article 35, then this
Lease shall remain in full force and effect, and Landlord shall, within a
reasonable time thereafter, repair or reconstruct the remaining portion of the
Building to the extent necessary to make the same a complete architectural unit;
provided, that in complying with its obligations hereunder, Landlord shall not
be required to expend more than the net proceeds of the condemnation award which
are paid to Landlord. Upon any such partial taking, Landlord shall have the
right to reduce the Operating Expense Base Amount by an amount equal to the
product of (x) the amount of property tax savings to Landlord arising from such
partial taking, as determined by Landlord in its sole but reasonable discretion,
divided by the number of square feet of Rentable Office Floor Area of the
Building, multiplied by (y) the number of square feet of Rentable Floor Area of
the Premises.

                  (d) All compensation awarded or paid to Landlord upon a total
or partial taking of the Premises or the Project shall belong to and be the
property of Landlord without any participation by Tenant. Nothing herein shall
be construed to preclude Tenant from prosecuting any claim directly against the
condemning authority for loss of business, for damage to, and cost of removal
of, trade fixtures, furniture and other personal property belonging to Tenant,
and for the unamortized cost of leasehold improvements to the extent the same
were installed at Tenant's expense (and not with the proceeds of the Tenant
Improvement Allowance); provided, however, that no such claim shall diminish or
adversely affect Landlord's award.

                  (e) Notwithstanding anything to the contrary contained in this
Article 35, if, during the Lease Term, the use or occupancy of any part of the
Project or the Premises shall be taken or appropriated temporarily for any
public or quasi-public use under any governmental law, ordinance or regulation,
or by right of eminent domain, this Lease shall be and remain unaffected by such
taking or appropriation and

                                       11
<PAGE>
 
Rent shall abate during such period. In the event of any such temporary
appropriation or taking, Tenant shall be entitled to receive that portion of any
award which represents compensation for the loss of use or occupancy of the
Premises during the Lease Term, and Landlord shall be entitled to receive that
portion of any award which represents the cost of restoration and compensation
for the loss of use or occupancy of the Premises after the end of the Lease
Term.

         36. Parties. The term "Landlord", as used in this Lease, shall include
Landlord and its successors and assigns. It is hereby covenanted and agreed by
Tenant that should Landlord's interest in the Premises cease to exist for any
reason during the Lease Term, then notwithstanding the happening of such event,
this Lease nevertheless shall remain in full force and effect, and Tenant hereby
agrees to attorn to the then owner of the Premises. The term "Tenant" shall
include Tenant and its heirs, legal representatives and successors, and shall
also include Tenant's assignees and sublessees, if this Lease shall be validly
assigned or the Premises sublet for the balance of the Lease Term or any
renewals or extensions thereof. In addition, Landlord and Tenant covenant and
agree that Landlord's right to transfer or assign Landlord's interest in and to
the Premises, or any part or parts thereof, shall be unrestricted, and that in
the event of any such transfer or assignment by Landlord which includes the
Premises, Landlord's obligations to Tenant hereunder shall cease and terminate,
and Tenant shall look only and solely to Landlord's assignee or transferee for
performance thereof.

         37. Liability of Landlord/Tenant.

                  (a) Tenant hereby indemnifies Landlord from and agrees to hold
Landlord harmless against, any and all liability, loss, cost, damage or expense,
including, without limitation, court costs and reasonable attorneys' fees,
imposed on Landlord by any person whomsoever, caused by the negligence or
willful misconduct of Tenant, or any of its employees and for its negligence in
selecting or monitoring the actions of its contractors, agents, subtenants or
invitees, or otherwise occurring in connection with any default of Tenant
hereunder. The provisions of this Article 37 shall survive any termination of
this Lease.

                  (b) Landlord hereby indemnifies Tenant from and agrees to hold
Tenant harmless against, any and all liability, loss, cost, damage or expense,
including, without limitation, court costs and reasonable attorneys' fees
actually incurred, imposed on Tenant by any person whomsoever, caused by the
negligence or willful misconduct of Landlord or any of its employees or for its
negligence in selecting or monitoring the actions or its agents, contractors or
invitees, or otherwise occurring in connection with any default of Landlord
hereunder.

                  (c) The provisions of this Article 37 shall survive the
expiration or any termination of this Lease.

         38. Relocation of the Premises. [INTENTIONALLY DELETED].

         39. Force Majeure. In the event of strike, lockout, labor trouble,
civil commotion, Act of God, or any other cause beyond a party's control
(collectively "force majeure") resulting in Landlord's inability to supply the
services or perform the other obligations required of Landlord hereunder, this
Lease shall not terminate and Tenant's obligation to pay Rent and all other
charges and sums due and payable by Tenant shall not be affected or excused and
Landlord shall not be considered to be in default under this Lease. If, as a
result of force majeure, Tenant is delayed in performing any of its obligations
under this Lease, other than Tenant's obligation to pay Rent and all other
charges and sums payable by Tenant hereunder, Tenant's performance shall be
excused for a period equal to such delay and Tenant shall not during such period
be considered to be in default under this Lease with respect to the obligation,
performance of which has thus been delayed. 40. Landlord's Liability. Landlord
shall have no personal liability with respect to any of the provisions of this
Lease. If Landlord is in default with respect to its obligations under this
Lease, Tenant shall look solely to the equity of Landlord in and to the Building
and the Land and the proceeds thereof for satisfaction of Tenant's remedies, if
any. It is expressly understood and agreed that Landlord's liability under the
terms of this Lease shall in no event exceed the amount of its interest in and
to said Land and Building. In no event shall any partner of Landlord nor any
joint venturer in Landlord, nor any officer, director or shareholder of Landlord
or any such partner or joint venturer of Landlord be personally liable with
respect to any of the provisions of this Lease.

         41. Landlord's Covenant of Quiet Enjoyment. Provided Tenant performs
the terms, conditions and covenants of this Lease, and subject to the terms and
provisions hereof, Landlord covenants and agrees to take all necessary steps to
secure and to maintain for the benefit of Tenant the quiet and peaceful
possession of the Premises, for the Lease Term, without hindrance, claim or
molestation by Landlord or any other person lawfully claiming under Landlord.

         42. Security Deposits.

                  (a) As security for Tenant's obligations to take possession of
the Premises in accordance with the terms of this Lease and to comply with all
of Tenant's covenants, warranties and agreements hereunder, Tenant shall deposit
with Landlord the sum set forth in Article 1(m(i) above on the date Tenant
executes and delivers this Lease to Landlord. Such amount shall be applied by
Landlord, without interest, to the first monthly installment(s) of Base Rental
as they become due hereunder. In the event Tenant fails to take possession of
the Premises as aforesaid, said sum shall be retained by Landlord for
application in reduction, but not in satisfaction, of damages suffered by
Landlord as a result of such breach by Tenant.

                  (b) As additional security for the faithful performance by
Tenant throughout the Lease Term, and any extensions or renewals thereof, of all
the terms and conditions of the Lease on the part of Tenant to be performed,
Tenant shall deposit with Landlord the sum set forth in Article 1(m)(ii) above
on the date Tenant executes and delivers this Lease to Landlord. Such amount
shall be returned to

                                       12
<PAGE>
 
Tenant, without interest, within twenty (20) days after the day set for the
expiration of the Lease Term, or any extension or renewal thereof, provided
Tenant has fully and faithfully observed and performed all of the terms,
covenants, agreements, warranties and conditions hereof on its part to be
observed and performed. Landlord shall have the right to apply all or any part
of said deposit toward the cure of any default of Tenant. If all or any part of
said security deposit is so applied by Landlord, then Tenant shall immediately
pay to Landlord an amount sufficient to return said security deposit to the
balance on deposit with Landlord prior to said application.

                  (c) In the event of a sale or transfer of Landlord's interest
in the Premises or the Building or a lease by Landlord of the Building, Landlord
shall have the right to transfer the within described security deposits to the
purchaser or lessor, as the case may be, and Landlord shall be relieved of all
liability to Tenant for the return of such security deposits. Tenant shall look
solely to the new owner or lessor for the return of said security deposits. The
security deposits shall not be mortgaged, assigned or encumbered by Tenant. In
the event of a permitted assignment under this Lease by Tenant, the security
deposits shall be held by Landlord as a deposit made by the permitted assignee
and Landlord shall have no further liability with respect to the return of said
security deposits to the original Tenant.

                  (d) Neither Landlord nor its agents shall be required to keep
the security deposits separate from their general accounts, it being agreed that
the security deposits may be commingled with other funds of Landlord or of its
agents. It is further agreed and acknowledged by Tenant that Landlord or its
agents shall have the right to deposit the security deposits in an
interest-bearing account, and all interest accrued on the security deposits
shall belong to Landlord and will be retained by Landlord as its property.

         43. Hazardous Substances. Tenant hereby covenants and agrees that
Tenant shall not cause or permit any "Hazardous Substances" (as hereinafter
defined) to be generated, placed, held, stored, used, located or disposed of at
the Project or any part thereof, except for Hazardous Substances as are commonly
and legally used or stored as a consequence of using the Premises for general
office and administrative purposes, but only so long as the quantities thereof
do not pose a threat to public health or to the environment or would necessitate
a "response action", as that term is defined in CERCLA (as hereinafter defined),
and so long as Tenant strictly complies or causes compliance with all applicable
governmental rules and regulations concerning the use or production of such
Hazardous Substances. For purposes of this Article 43, "Hazardous Substances"
shall mean and include those elements or compounds which are contained in the
list of Hazardous Substances adopted by the United States Environmental
Protection Agency (EPA) or the list of toxic pollutants designated by Congress
or the EPA which are defined as hazardous, toxic, pollutant, infectious or
radioactive by any other federal, state or local statute, law, ordinance, code,
rule, regulation, order or decree regulating, relating to or imposing liability
(including, without limitation, strict liability) or standards of conduct
concerning, any hazardous, toxic or dangerous waste, substance or material, as
now or at any time hereinafter in effect (collectively "Environmental Laws").
Tenant hereby agrees to indemnify Landlord and hold Landlord harmless from and
against any and all losses, liabilities, including strict liability, damages,
injuries, expenses, including reasonable attorneys' fees, costs of settlement or
judgment and claims of any and every kind whatsoever paid, incurred or suffered
by, or asserted against, Landlord by any person, entity or governmental agency
for, with respect to, or as a direct or indirect result of, the presence in, or
the escape, leakage, spillage, discharge, emission or release from, the Premises
of any Hazardous Substances caused by Tenant (including, without limitation, any
losses, liabilities, including strict liability, damages, injuries, expenses,
including reasonable attorneys' fees, costs of any settlement or judgment or
claims asserted or arising under the Comprehensive Environmental Response,
Compensation and Liability Act ["CERCLA"], any so-called federal, state or local
"Superfund" or "Superlien" laws or any other Environmental Law); provided,
however, that the foregoing indemnity is limited to matters arising solely from
Tenant's violation of the covenant contained in this Article. The obligations of
Tenant under this Article shall survive any expiration or termination of this
Lease. Landlord acknowledges that Tenant intends to keep gel cell batteries in
the Premises and intends to store and use diesel fuel in customary quantities in
order to operate Tenant's generator. Landlord agrees that the storage and use of
such items shall not constitute a violation of this paragraph 43 of the Lease.

         Landlord represents that to the best of Landlord's knowledge the
Premises, the Building and the real property on which the Building is located
are free from asbestos and other Hazardous Substances and that, to the best of
Landlord's knowledge, there has never been environmental pollution on the real
property on which the Building is located. A Phase I Environmental Audit Report
on the Building and said real property was prepared in 1992 and is available to
Tenant for review. Tenant is hereby notified of a tenant's material testing lab
located on Level "C" (Loading Decks) of the Building; the lab is leased and
operated by a tenant in the Building. Landlord shall promptly remediate any
Hazardous Substances in the Project, Building or Premises and not released by
Tenant.

         44. Submission of Lease. The submission of this Lease for examination
does not constitute an offer to lease and this Lease shall be effective only
upon execution hereof by Landlord and Tenant and upon execution of any required
Guaranty Agreement annexed hereto and incorporated herein as Exhibit "F".

         45. Severability. If any clause or provision of the Lease is illegal,
invalid or unenforceable under present or future laws, the remainder of this
Lease shall not be affected thereby, and in lieu of each clause or provision of
this Lease which is illegal, invalid or unenforceable, there shall be added as a
part of this Lease a clause or provision as nearly identical to the said clause
or provision as may be legal, valid and enforceable.

         46. Entire Agreement. This Lease contains the entire agreement of the
parties and no representations, inducements, promises or agreements, oral or
otherwise, between the parties not embodied herein shall be of any force or
effect. No failure of Landlord to exercise any power given Landlord hereunder,
or to insist upon strict compliance by Tenant with any obligation of Tenant
hereunder, and no custom or practice of the parties at variance with the terms
hereof, shall constitute a waiver of Landlord's right to demand exact compliance
with the

                                       13
<PAGE>
 
terms hereof. This Lease may not be altered, waived, amended or extended except
by an instrument in writing signed by Landlord and Tenant. This Lease is not in
recordable form, and Tenant agrees not to record or cause to be recorded this
Lease or any short form or memorandum thereof.

         47. Headings. The use of headings herein is solely for the convenience
of indexing the various paragraphs hereof and shall in no event be considered in
construing or interpreting any provision of this Lease.

         48. Broker. Broker(s) [as defined in Article 1(p)] is(are) entitled to
a leasing commission from Landlord by virtue of this Lease, which leasing
commission shall be paid by Landlord to Broker(s) in accordance with the terms
of a separate agreement between Landlord and Broker(s). Tenant hereby authorizes
Broker(s) and Landlord to identify Tenant as a tenant of the Building and to
state the amount of space leased by Tenant in advertisements and promotional
materials relating to the Building. Tenant represents and warrants to Landlord
that [except with respect to any Broker(s) identified in Article 1(p)
hereinabove, which has(have) acted as agent for Tenant (and not for Landlord) in
this transaction] no broker, agent, commission salesperson, or other person has
represented Tenant in the negotiations for and procurement of this Lease and of
the Premises and that [except with respect to any Broker(s) identified in
Article 1(p) hereinabove] no commissions, fees or compensation of any kind are
due and payable in connection herewith to any broker, agent, commission
salesperson or other person as a result of any act or agreement of Tenant.
Tenant agrees to indemnify and hold Landlord harmless from all loss, liability,
damage, claim, judgment, cost or expense (including reasonable attorneys' fees
and court costs) suffered or incurred by Landlord as a result of a breach by
Tenant of the representation and warranty contained in the immediately preceding
sentence or as a result of Tenant's failure to pay commissions, fees or
compensation due to any broker who represented Tenant, whether or not disclosed,
or as a result of any claim for any fee, commission or similar compensation with
respect to this Lease made by any broker, agent or finder [other than the
Broker(s) identified in Article 1(p) hereinabove] claiming to have dealt with
Tenant, whether or not such claim is meritorious. The parties hereto do hereby
acknowledge and agree that COMPASS Management and Leasing, Inc., a subsidiary of
Equitable Real Estate Investment Management, Inc., has acted as agent for
Landlord in this transaction and shall be paid a commission by Landlord in
connection with this transaction pursuant to the terms of a separate written
commission agreement. COMPASS Management and Leasing, Inc. has not acted as
agent for Tenant in this transaction. Landlord hereby warrants and represents to
Tenant that Landlord has not dealt with any broker, agent or finder other than
COMPASS Management and Leasing, Inc. in connection with this Lease, and,
Landlord hereby agrees to indemnity and hold Tenant harmless from and against
any and all loss, damage, liability, claim, judgment, cost or expense
(including, but not limited to, reasonable attorneys' fees and court costs) that
may be incurred or suffered by Tenant because of any claim for any fee,
commission or similar compensation with respect to this Lease made by any
broker, agent or finder claiming to have represented Landlord.

         49. Governing Law. The laws of the State of Georgia shall govern the
validity, performance and enforcement of this Lease.

         50. Authority. If Tenant executes this Lease as a corporation, each of
the persons executing this Lease on behalf of Tenant does hereby personally
represent and warrant that Tenant is a duly incorporated or a duly qualified (if
a foreign corporation) corporation and is fully authorized and qualified to do
business in the State in which the Premises are located, that the corporation
has full right and authority to enter into this Lease, and that each person
signing on behalf of the corporation is an officer of the corporation and is
authorized to sign on behalf of the corporation. If Tenant signs as a
partnership, joint venture or sole proprietorship or other business entity (each
being herein called "Entity"), each of the persons executing on behalf of Tenant
does hereby covenant and warrant that Tenant is a duly authorized and existing
Entity, that Tenant has full right and authority to enter into this Lease, that
all persons executing this Lease on behalf of the Entity are authorized to do so
on behalf of the Entity, and that such execution is fully binding upon the
Entity and its partners, joint venturers or principal, as the case may be. Upon
the request of Landlord, Tenant shall deliver to Landlord documentation
satisfactory to Landlord evidencing Tenant's compliance with this Article, and
Tenant agrees to promptly execute all necessary and reasonable applications or
documents as reasonably requested by Landlord, required by the jurisdiction in
which the Premises is located, to permit the issuance of necessary permits and
certificates for Tenant's use and occupancy of the Premises.

         51. Joint and Several Liability. If Tenant comprises more than one
person, corporation, partnership or other entity, the liability hereunder of all
such persons, corporations, partnerships or other entities shall be joint and
several.

         52. Special Stipulations. The special stipulations attached hereto as
Exhibit "G" are hereby incorporated herein by this reference as though fully set
forth (if none, so state). To the extent the special stipulations conflict with
or are inconsistent with the foregoing provisions of this Lease or any exhibit
to this Lease, the special stipulations shall control.

         IN WITNESS WHEREOF, the parties have hereunto set their hands and seals
as of the day, month and year first above written.

                                    LANDLORD:

                                    THE EQUITABLE LIFE ASSURANCE SOCIETY OF
                                    THE UNITED STATES
Date executed by Landlord:
  2-5-99
- ------------                        By: /s/ Terrell E. Daffer
                                       -----------------------------
                                            Terrell E. Daffer
                                    Title:  Investment Officer
                                          --------------------------

                                       14
<PAGE>
 
                                          [SEAL]


                                    TENANT:

                                    [Corporate tenant]

                                    FOCAL COMMUNICATIONS CORPORATION, a
                                    Delaware corporation


Date executed by Tenant:
Feb 2nd 1999
- ------------                        By: /s/ Brian ????????????
                                       -------------------------------
                                    Title:  Executive Vice President
                                          ----------------------------
                                    Attest: /s/ Sharla ???????
                                           ---------------------------
                                    Title: Administrative Assistant
                                          ----------------------------

                                               [CORPORATE SEAL]

                                       15
<PAGE>
 
                              RULES AND REGULATIONS
                              ---------------------

         In the event of a conflict between the Rules and Regulations and the
Lease, the Lease shall control.

1.       No sign, picture, advertisement or notice visible from the exterior of
         the Premises shall be installed, affixed, inscribed, painted or
         otherwise displayed by Tenant on any part of the Premises or the
         Building unless the same is first approved by Landlord.  Any such sign,
         picture, advertisement or notice approved by Landlord shall be painted
         or installed for Tenant at Tenant's cost by Landlord or by a party
         approved by Landlord.  No awnings, curtains, blinds, shades or screens
         shall be attached to or hung in, or used in connection with any window
         or door of the Premises without the prior consent of Landlord,
         including approval by Landlord of the quality, type, design, color and
         manner of attachment.  Landlord will not unreasonably withhold its
         consent to Tenant's covering certain exterior windows in the Premises.

2.       Tenant agrees that its use of electrical current shall never exceed the
         capacity of existing feeders, risers or wiring installation.

3.       The Premises shall not be used for storage of merchandise held for sale
         to the general public.  Tenant shall not do or permit to be done in or
         about the Premises or Building anything which shall increase the rate
         of insurance on said Building or obstruct or interfere with the rights
         of other lessees of Landlord or annoy them in any way, including, but
         not limited to, using any musical instrument, making loud or unseemly
         noises, or singing, etc.  The Premises shall not be used for sleeping
         or lodging.  No cooking or related activities shall be done or
         permitted by Tenant in the Premises except with permission of Landlord.
         Tenant will be permitted to use for its own employees within the
         Premises a small microwave oven and Underwriters' Laboratory approved
         equipment for brewing coffee, tea, hot chocolate and similar beverages,
         provided that such use is in accordance with all applicable federal,
         state, county and city laws, codes, ordinances, rules and regulations.
         No vending machines of any kind will be installed, permitted or used on
         any part of the Premises without the prior consent of Landlord.  No
         part of said Building or the Premises shall be used for gambling,
         immoral or other unlawful purposes.  No intoxicating beverage shall be
         sold in said Building or the Premises without the prior written consent
         of Landlord.  No area outside of the Premises shall be used for storage
         purposes at any time.

4.       Tenant must obtain Landlord's approval of all contractors, contractors'
         representatives, major sub-contractors and installation technicians
         rendering any service on or to the Premises for Tenant, before
         performance of any contractual service.  This provision shall apply to
         all work performed on or about the Premises, including without
         limitation installation of telephones, facsimile equipment, electrical
         devices and attachments and installations of any nature affecting
         floors, walls, woodwork, trim, windows, ceilings and equipment or any
         other physical portion of the Premises or the Building, and any
         contractor or sub-contractor performing work in the Premises or the
         Building for Tenant shall be subject to these Rules and Regulations.
         Any alterations, additions or improvements to the Premises made by
         Tenant must conform to all applicable governmental codes and
         regulations.

5.       No birds or animals of any kind shall be brought into the Building
         (other than trained seeing-eye dogs required to be used by the visually
         impaired). No bicycles, motorcycles or other motorized vehicles shall
         be brought into the Building.

6.       The sidewalks, entrances, passages, corridors, halls, elevators and
         stairways in the Building shall not be obstructed by Tenant or used for
         any purposes other than those for which same were intended as ingress
         and egress. No windows, floors or skylights that reflect or admit light
         into the Building shall be covered or obstructed by Tenant. Toilets,
         wash basins and sinks shall not be used for any purpose other than
         those for which they were constructed, and no sweeping, rubbish or
         other obstructing or improper substances shall be thrown therein. Any
         damage resulting to them, or to heating apparatus, from misuse by
         Tenant or its employees, shall be borne by Tenant.

7.       Only three (3) keys for the Premises will be furnished to Tenant
         without charge.  Landlord may make a reasonable charge for any
         additional keys.  Only one (1) access card for the Building will be
         furnished to Tenant without charge.  Landlord may make a reasonable
         charge for any additional access cards.  No additional lock, latch or
         bolt of any kind shall be placed upon any door nor shall any changes be
         made in existing locks without written consent of Landlord and Tenant
         shall in each such case furnish Landlord with a key for any such lock.
         At the termination of the Lease, Tenant shall return to Landlord all
         keys and access cards furnished to Tenant by Landlord, or otherwise
         procured by Tenant, and in the event of loss of any keys or access
         cards so furnished, Tenant shall pay to Landlord the cost thereof.

8.       Landlord shall have the right to prescribe the weight, position and
         manner of installation of heavy articles such as safes, machines,
         batteries, generators and other equipment brought into the Building. No
         safes, furniture, boxes, large parcels or other kind of freight shall
         be taken to or from the Premises or allowed in any elevator, hall or
         corridor except at times allowed by Landlord.  No deliveries shall be
         made in passenger elevators.  Tenant shall make prior arrangements with
         Landlord for use of freight elevator for the purpose of transporting
         such articles and such articles may be taken in or out of said Building
         only between or during such hours as may be arranged with and
         designated by Landlord.  The persons employed to move the same must be
         approved by Landlord.  No hand trucks, except those equipped with
         rubber tires and side guards, shall be permitted in the Building.  No
         hand trucks shall be permitted in any passenger elevator.  In no event
         shall any weight be placed upon any floor by Tenant so as to exceed the
         design conditions of the floors at the applicable locations.

                              Rule and Regulations
                              --------------------
                                  Page 1 of 3
<PAGE>
 
9.       Tenant shall not cause or permit any gases, liquids or odors to be
         produced upon or permeate from the Premises, and no flammable,
         combustible or explosive fluid, chemical, substance or item (including,
         without limitation, natural Christmas trees) shall be brought into the
         Building. No acids, vapors or other harmful materials shall be
         discharged or permitted to be discharged into the waste lines, vents or
         flues of the Building. The water closets and other water fixtures shall
         not be used for any purpose other than those for which they were
         designed or constructed. No person shall waste water by interfering
         with the faucets or otherwise.

10.      Every person, including Tenant, its employees and visitors, entering
         and leaving the Building may be questioned by a watchman as to that
         person's business therein and may be required to sign such person's
         name on a form provided by Landlord for registering such person;
         provided that, except for emergencies or other extraordinary
         circumstances, such procedures shall not be required between the hours
         of 7:00 a.m. and 6:00 p.m., on all days except Saturdays, Sundays and
         Holidays.  Landlord may also implement a card access security system to
         control access during such other times.  Landlord shall not be liable
         for excluding any person from the Building during such other times, or
         for admission of any person to the Building at any time, or for damages
         or loss for theft resulting therefrom to any person, including Tenant.

11.      Tenant's moving in or out of the Building of furniture or office
         supplies and equipment, or dispatch or receipt of any bulky merchandise
         or materials, which require use of elevators or stairways or movement
         through the Building entrances or lobby, shall be restricted to hours
         designated by Landlord.  Tenant must provide Landlord with at least two
         (2) business days' prior written notice of Tenant's desire to move any
         such furniture, supplies or equipment.  All such movement shall be
         under supervision of Landlord and carried out in a manner which has
         been prearranged between Tenant and Landlord before performance.  Such
         prearrangement will include a determination by Landlord of the time,
         method and routing of such movement and limitations imposed by safety
         or other concerns, which determination may prohibit any article,
         equipment or any other item from being brought into the Building.

12.      Unless agreed to in writing by Landlord, Tenant shall not employ any
         person other than Landlord's contractors for the purpose of cleaning
         and taking care of the Premises. Cleaning service will not be furnished
         on nights when rooms are occupied after 6:30 p.m., unless, by agreement
         in writing, service is extended to a later hour for specifically
         designated rooms. Landlord shall not be responsible for any loss,
         theft, mysterious disappearance of or damage to, any property, however
         occurring. Only persons authorized by Landlord may furnish ice,
         drinking water, towels, and other similar services within the Building
         and only at hours and under regulations fixed by Landlord.

13.      No connection shall be made to the electric wires or gas or electric
         fixtures, without the consent in writing on each occasion of Landlord.
         All glass, locks and trimmings in or upon the doors and windows of the
         Premises shall be kept whole and in good repair. Tenant shall not
         injure, overload or deface the Building, the woodwork or the walls of
         the Premises, nor permit any noisome, noxious, noisy or offensive
         business.

14.      If Tenant requires wiring for a bell or buzzer system, such wiring
         shall be done by the electrician of Landlord only, and no outside
         wiring persons shall be allowed to do work of this kind unless by the
         written permission of Landlord or its representatives. If telegraph or
         telephonic service is desired, the wiring for same shall be approved by
         Landlord, and no boring or cutting for wiring shall be done unless
         approved by Landlord or its representatives, as stated. The electric
         current shall not be used for power or heating unless written
         permission to do so shall first have been obtained from Landlord or its
         representatives in writing, and at an agreed cost to Tenant.

15.      Tenant and its employees and invitees shall observe and obey all
         parking and traffic regulations as imposed by Landlord.  All vehicles
         shall be parked only in areas designated therefor by Landlord. Parking
         in a parking garage or area shall be in compliance with all parking
         rules and regulations including any sticker or other identification
         system established by Landlord. Failure to observe the rules and
         regulations shall terminate the rights of any Tenant's employees,
         agents, guests or invitees so violating said rules and regulations to
         use the parking garage or area and subject the vehicle in violation of
         the parking rules and regulations to removal and impoundment.  No
         termination of parking privileges or removal or impoundment of a
         vehicle shall create any liability on Landlord or be deemed to
         interfere with Tenant's right to possession of the Premises.  Vehicles
         must be parked entirely within the stall lines, and all directional
         signs, arrows and posted speed limits must be observed.  Parking is
         prohibited in areas not striped for parking, in aisles where "No
         Parking" signs are posted, on ramps, in cross hatched areas, and in
         other areas as may be designated by Landlord.  Parking stickers or
         other forms of identification supplied by Landlord shall remain the
         property of Landlord and not the property of Tenant and are not
         transferable.  Every person is required to park and lock his or her
         vehicle.  All responsibility for damage to vehicles or persons is
         assumed by the owner of the vehicle or the driver thereof.

16.      Canvassing, peddling, soliciting and distribution of handbills or any
         other written materials in the Building are prohibited, and Tenant
         shall cooperate to prevent the same.

17.      Landlord shall have the right to change the name of the Building and to
         change the street address of the Building, provided that in the case of
         a change in the street address, Landlord shall give Tenant not less
         than 180 days' prior notice of the change, unless the change is
         required by governmental authority. Tenant shall not use the name of
         the Building or of Landlord in any advertising (except to identify the
         location of Tenant's business), without the prior written consent of
         Landlord.

                              Rule and Regulations
                              --------------------
                                  Page 2 of 3
<PAGE>
 
18.      The directory of the Building will be provided for the display of the
         name and location of the tenants. Any additional name which Tenant
         shall desire to place upon said directory must first be approved by
         Landlord, and if so approved, a reasonable charge will be made
         therefor.

19.      Smoking is prohibited in the main Building lobby, public corridors,
         elevator lobbies, service elevator vestibules, parking levels,
         stairwells, restrooms and other common areas within the Building.

20.      The employees, licensees and guests of Tenant shall wear appropriate
         attire at all times in or about the Premises and the Building. This
         shall not prevent Tenant from having "casual days," but any such casual
         dress shall be appropriate for an office environment and shall not
         disrupt the decorum and professional atmosphere of the Building.

21.      Tenant shall not contract for placement, installation or maintenance on
         the Premises of any vending machine for the sale of food or beverages,
         without having first provided the restaurant operator presently located
         within the Building an opportunity to negotiate with Tenant for the
         right to place such machines in the Premises and without having first
         obtained the written consent of Landlord. Tenant shall enter into such
         negotiations with any such restaurant operator in good faith.
         Notwithstanding the foregoing, Tenant shall not place or have placed on
         the Premises any vending machine for the sale of sandwich products.

22.      No person shall disturb occupants of the Building by the use of any
         radios, record players, tape recorders, musical instruments or similar
         equipment, the making of unseemly noises or any unreasonable use, nor
         in any manner create any nuisance.

23.      Tenant will comply with all reasonable security measures instituted by
         Landlord so as to provide the necessary security for the Premises and
         the Building, it being acknowledged that tenants of the Building may
         from time to time have differing needs with regard to security and that
         reasonable security measures applicable to some or all tenants may be
         instituted by Landlord in its attempt to cooperate in meeting such
         needs.  All personal property (including but not limited to automobiles
         and their contents) and money brought into the Building or on the
         Premises by Tenant, its agents, employees, invitees, visitors and
         contractors shall be at Tenant's sole risk except with respect to
         matters arising out of the negligence or willful misconduct of the
         direct employees of Landlord or Landlord's managing agent or if
         Landlord was negligent in its hiring or failing to discharge the
         security company.  Provided Landlord uses due care in hiring or
         discharging the security company Landlord shall have no liability
         arising out of the actions of the employees of the security company or
         out of the failure of such security company or its employees to provide
         security services as described herein.

24.      Tenant and its employees, agents, contractors, licensees and invitees
         shall comply with reasonable rules and regulations promulgated by
         Landlord for the Building parking areas. Landlord agrees to apply and
         enforce such rules and regulations uniformly as to all tenants of the
         Building. If Tenant or any of Tenant's employees, agents, contractors,
         licensees, invitees, guests or visitors fail to comply with such
         reasonable rules and regulations, Landlord, after giving written notice
         to Tenant of such violation, shall have the right to remove such
         vehicle at Tenant's expense.

25.      All requests for after hours air conditioning must be submitted in
         writing to Landlord by 12:00 p.m. on the day desired for weekday
         requests and by 12:00 p.m. on Friday for weekend requests.

26.      Landlord may waive any one or more of these Rules and Regulations for
         the benefit of any particular lessee, but no such waiver by Landlord
         shall be construed as a waiver of such Rules and Regulations in favor
         of any other lessee, nor prevent Landlord from thereafter enforcing any
         such Rules and Regulations against any or all of the other lessees of
         the Building.

27.      These Rules and Regulations are supplemental to, and shall not be
         construed to in any way modify or amend, in whole or in part, the
         terms, covenants, agreements and conditions of any lease of any
         premises in the Building.

28.      Landlord reserves the right to make such other and reasonable Rules and
         Regulations as in its judgment may from time to time be needed for the
         safety, care and cleanliness of the Building and the Land, and for the
         preservation of good order therein.

29.      Landlord reserves the right to require Tenant to temporarily evacuate
         the Premises and the Project, or temporarily restrict Tenant's access
         thereto, if Landlord, in its sole discretion, deems such action
         necessary to protect or otherwise safeguard the health or safety of
         Tenant, any other Building tenant, or any other Building occupant from
         any threat or perceived threat of any kind made upon the Building, the
         Project or any tenant of Landlord.  Any such action taken by Landlord
         shall not be deemed an actual or constructive eviction of Tenant, a
         breach of the covenant of quiet enjoyment or an interruption of
         Tenant's business, and Tenant shall not be entitled to any abatement of
         rent, loss or profits or damages for any injury or inconvenience
         occasioned thereby.


                              Rule and Regulations
                              --------------------
                                  Page 3 of 3
<PAGE>
 
                                   EXHIBIT "A"
                                   -----------

                                LEGAL DESCRIPTION
                                -----------------


Tract I
- -------

ALL THAT TRACT OR PARCEL OF LAND lying and being in the City of Atlanta in Land
Lot 78, 14th District, Fulton County, Georgia, and being more particularly
described as follows:

BEGINNING at a P.K. nail at the intersection of the northern right-of-way line
of Harris Street (60-foot right-of-way) and the eastern right-of-way line of
Techwood Drive (60-foot right-of-way) and running along said Techwood Drive
right-of-way line North 00 degrees 44' 41" East, a distance of 407.09 feet to a
point at the intersection of said eastern right-of-way line of Techwood Drive
and the southern right-of-way line of Baker Street (60-foot right-of-way);
thence leaving said eastern right-of-way line of Techwood Drive and running
along said southern right-of-way line of Baker Street the following courses and
distances: South 89 degrees 31' 21" East, a distance of 185.21 feet to a point;
South 89 degrees 30' 00" East, a distance of 75.23 feet to an iron pin; and
South 89 degrees 40' 44" East, a distance of 124.77 feet to a point at the
intersection of said Baker Street southern right-of-way line with the western
right-of-way line of Williams Street (60-foot right-of-way); thence leaving said
southern right-of-way line of Baker Street and running along said western
right-of-way line of Williams Street South 00 degrees 31' 33" West, a distance
of 145.22 feet to an iron pin; thence leaving said Williams Street right-of-way
line and running North 89 degrees 32' 53" West, a distance of 115.00 feet to a
point; running thence South 00 degrees 27' 07" West, a distance of 31.34 feet to
a point; running thence North 89 degrees 32' 53" West, a distance of 9.94 feet
to a point; running thence South 00 degrees 33' 47" West, a distance of 33.42
feet to a point; running thence South 89 degrees 03' 03" East, a distance of
125.03 feet to a point on said western right-of-way line of Williams Street;
running thence along said Williams Street right-of-way line the following
courses and distances: South 00 degrees 57' 00" West, a distance of 54.01 feet
to a point; South 20 degrees 27' 07" East, a distance of 34.00 feet to a point;
and South 00 degrees 24' 39" West, a distance of 106.00 feet to a bolt found at
the intersection of said Williams Street western right-of-way line and said
Harris Street northern right-of-way line; thence leaving said Williams Street
right-of-way line and running along said Harris Street right-of-way line the
following courses and distances; South 89 degrees 59' 50" West, a distance of
100.00 feet to an iron pin; North 89 degrees 42' 18" West, a distance of 50.02
feet to an iron pin; North 89 degrees 48' 37" West, a distance of 49.85 feet to
an iron pin; and North 89 degrees 46' 24" West, a distance of 187.43 feet to a
P.K. nail, being the POINT OF BEGINNING; according to that certain Boundary
Survey for Inforum Limited/Equitable Life Assurance Society of the United States
Joint Venture, by Construction & Land Surveys, Inc., bearing the seal of Donald
K. Stokes, Georgia Registered Land Surveyor No. 1896, dated August 5, 1987,
which date is identified as Revision 5 on said boundary survey.


Tract II
- --------

ALL THAT TRACT OR PARCEL OF LAND lying and being in the City of Atlanta in Land
Lot 78, 14th District, Fulton County, Georgia, and being more particularly
described as follows:

BEGIN at an iron pin on the western right-of-way line of Williams Street
(60-foot right-of-way), said iron pin being measured South 00 degrees 31' 33"
West, a distance of 145.22 feet from the intersection of said western
right-of-way line of Williams Street and the southern right-of-way line of Baker
Street (60-foot right-of-way); thence leaving said western right-of-way line of
Williams Street and running North 89 degrees 32' 53" West, a distance of 115.00
feet to a point; running thence South 00 degrees 27' 07" West, a distance of
31.34 feet to a point; running thence North 89 degrees 32' 53" West, a distance
of 9.94 feet to a point; running thence South 00 degrees 33' 47" West, a
distance of 33.42 feet to a point; running thence South 89 degrees 03' 03" East,
a distance of 125.03 feet to a point on said Williams Street western
right-of-way line; running thence along said Williams Street right-of-way line
the following courses and distances; North 00 degrees 24' 56" East, a distance
of 34.50 feet to a point; and North 00 degrees 24' 39" East, a distance of 31.34
feet to an iron pin, being the POINT OF BEGINNING; in accordance with that
certain Boundary Survey for Inforum Limited/Equitable Life Assurance Society of
the United States Joint Venture, by Construction & Land Surveys, Inc., bearing
the seal of Donald K. Stokes, Georgia Registered Land Surveyor No. 1896, dated
August 5, 1987, which date is identified as Revision 5 on said boundary survey.
<PAGE>
 
                                  EXHIBIT "B"

                                   FLOOR PLAN


                           [FLOOR PLAN APPEARS HERE]



                                    INFORIUM
                                  LOBBY LEVEL
<PAGE>
 
                                   EXHIBIT "C"
                                   -----------

                               SUPPLEMENTAL NOTICE
                               -------------------


                  RE:  Lease dated as of ______________, 19__, by and between
_____________________ , as Landlord, and _______________________, as Tenant.



Dear Sirs:


         Pursuant to Article 3 of the captioned Lease, please be advised as
follows:

         1.       The Term Commencement Date is the ________________ day of
                  ____________, 19__, and the Term Expiration Date  is the
                  ____________ day of _________________, __________, subject
                  however to the terms and provisions of the Lease.

         2.       The Rentable Floor Area of the Premises is square feet.

         3.       Terms denoted herein by initial capitalization shall have the
                  meanings ascribed thereto in the Lease.



                                    LANDLORD:
                                    ---------


                                    THE EQUITABLE LIFE ASSURANCE SOCIETY OF
                                    THE UNITED STATES


                                    By:
                                       ------------------------------------
                                       Title:
                                             ------------------------------
                                                       [SEAL]
<PAGE>
 
                                                      [FIRST GENERATION SPACE]

                                   EXHIBIT "D"
                                   -----------

                              TENANT'S CONSTRUCTION
                              ---------------------

 1.      Tenant, at Tenant's sole cost and expense, shall cause to be prepared
         by its architect and/or designer the following:

         (a)      One (1) schematic partition layout sufficient in detail for
                  Landlord's approval of the location of partitions.

 2.      Tenant, at Tenant's sole cost and expense, shall cause to be prepared
         by its architect and/or designer and/or engineer the following:

         (a)      Any additional modification desired by Tenant to the schematic
                  partition plan described in Paragraph 1 above.

         (b)      Complete, finished, detailed construction documents and
                  specifications for Tenant's partition layout, reflected
                  ceiling and other installations for the work to be done by
                  Tenant under Paragraph 4 hereof, which shall be prepared by
                  Tenant's architect and/or designer.

         (c)      Complete mechanical and electrical plans and specifications
                  where necessary for installation of air conditioning system
                  and ductwork, electrical, plumbing and other engineering plans
                  for the work to be done by Tenant under Paragraph 4 hereof,
                  which shall be prepared by Tenant's architect and/or designer
                  and/or engineer.

         (d)      Any subsequent modifications to the construction documents and
                  specifications desired by Tenant.

         All such plans and specifications are expressly subject to Landlord's
         approval and shall comply with all applicable laws, rules and
         regulations. Tenant covenants and agrees to cause said plans and
         specifications to be delivered to Landlord by April 1, 1999 (a)
         approved by Tenant and Tenant's architect (if applicable) and (b) in a
         form acceptable for issuance of a building permit and sufficient to be
         released for construction. Upon approval by Landlord, Tenant will cause
         said plans to be filed, if necessary, at Tenant's sole cost and expense
         with the appropriate governmental agencies in such form (building
         permit, alteration or other form) as Landlord may direct. Landlord
         shall not unreasonably withhold or delay its consent to Tenant's plans.
         Landlord shall have ten (10) days from receipt of Tenant's plan to
         review such plans (the "Plan Review Period"). In the event that
         Landlord disapproves of such plans, Landlord shall provide written
         notice of the plans within the Plan Review Period along with specific
         comments as to why the plans are unacceptable ("Landlord's Notice of
         Disapproval"). Within the ten (10) day period following Tenant's
         receipt of Landlord's Notice of Disapproval, Tenant and Landlord shall
         meet in good faith to resolve any objections to the plans.

         The Premises shall be deemed "ready for occupancy" [as that term is
         used in Article 1(i) of the Lease] when Tenant's construction, as
         provided in Paragraph 4 hereof, is substantially completed. In the
         event of any dispute as to when Tenant's construction has been
         substantially completed as aforesaid, the determination of Landlord's
         architect and/or designer shall be final and binding upon the parties.

 3.      Landlord agrees, at its sole cost and expense, to supply and install
         (except where indicated to the contrary) the following work in the
         Premises in accordance with Landlord's standard specification:

         (a)      A sprinkler system at a rate of not more than one (1)
                  sprinkler head for 225 square feet of usable area installed in
                  accordance with Landlord's Standard grid pattern that meets
                  NFPA guidelines. Tenant shall be responsible for the cost,
                  material and labor for the relocation of any sprinkler
                  components or the addition of any new sprinkler components
                  that are necessitate by Tenant's plan.

         (b)      Life Safety Equipment is Building Standard fire alarm devices,
                  including speakers and strobes, fire sprinkler loops,
                  including drops and smoke detectors as required by code.
                  Building fire alarm, enunciators, fire extinguishers, exit
                  light and ADA compliant strobes installed per Tenant's
                  occupancy requirements will be charged as part of the Tenant
                  Improvement Allowance.

         (c)      Building Standard Window covering installed on the West side
                  of the building only, which blinds shall be pulled to the top
                  and bagged in polyethylene until the completion of Tenant's
                  work.

         (d)      All exterior windows are floor to ceiling.

         (e)      Inside face of all demising walls shall be ready to accept
                  drywall, installation, spackle finish, tape, sanded and
                  eggshell paint.

         (f)      Core walls shall be framed drywalls, spackled finish, taped
                  and sanded from slab to ceiling level, ready to accept a wall
                  finish.


                                  Exhibit "D"
                                  -----------
                                  Page 1 of 3
<PAGE>
 
         (g)      Building columns in INFORUM are concrete and are not dry
                  walled. If Tenant requires columns to be dry wall finished
                  taped, and bedded, it will be charged against the Tenant's
                  Improvement Allowance.

         (h)      The base building HVAC system is designed for a capacity of
                  one (1) person/150/USF, to cool four (4) watts/USF, (separate
                  from base building HVAC systems), 20 CFM outside air per
                  person per the following criteria. Building Operating hours
                  are Monday to Friday 7:00 a.m. to 6:00 p.m. and Saturday 7:30
                  a.m. to 1:00 p.m. During building operating hours, Landlord
                  will maintain 75 degrees inside at 92 degrees dry bulb outside
                  in summer and 72 degrees inside at 17 degrees dry bulb outside
                  in winter.

         (i)      Landlord will provide partially completed air conditioning
                  system to include the supply ductwork, and one (1) Calibrated
                  thermostat or sensor (uninstalled). The air distribution duct
                  work is in place in the down stream side of the mixing boxes
                  (or fan coil units for the 5th and 6th floors). Spin-ins,
                  flex, interior supply diffusers and return air grids with slot
                  diffusers are stacked on the floor for Tenant's installation
                  at the perimeter for each zone. Final testing, adjustment and
                  balancing of Tenant's HVAC shaft be charged as part of Tenant
                  Improvement Allowance.

         (j)      Plumbing is available on the floor for installation of a
                  coffee bar/station, but the configuration of the floor below
                  shall dictate the exact location.

         (k)      Cabling rooms and cable risers are available for installation
                  of telephones and computer networks. All building cable
                  facilities are sufficient to support either an internally
                  operated PBX system or a local telephone provider's system, or
                  both.

         (l)      Electricity is supplied underground by the Georgia Power
                  Company from the Fowler Street Network Substation on four
                  separate parallel circuits. Four, 3,000 KVA transformers
                  reduce the voltage to 4.16 KV for distribution to the
                  building.

         (m)      Tenant shall be allowed to install, maintain and operate its
                  own internal voice and data communication systems. There are
                  no Shared Tenant Services available in INFORUM.

         (n)      INFORUM has Electrical Capacity of three phase, four wire
                  120/208 or 277/480 Volt.

         (o)      Ceiling Heights on the 5th and 6th floors are 14 feet slab, 12
                  1/2 to the beam. The Bridge Level is 22 feet slab to slab to
                  accommodate a finished ceiling of 14 feet. The Lobby Level is
                  26 feet slab to slab, with finished ceiling heights varying
                  from 10 to 17 feet depending on the location.

         (p)      Tenant will not be subject to a restocking charge if Tenant
                  elects to utilize its own materials. Landlord must approve all
                  materials used by Tenant prior to construction. Tenant will
                  receive credit by using its own materials, in lieu of
                  Landlord's Building Standard materials.

         (q)      Landlord will supply to Tenant all necessary floor plans,
                  including dimensional, structural, mechanical and electrical.

         (r)      The floor load in the Premises will be one hundred (100)
                  pounds per square foot which Tenant may upgrade at its expense
                  provided any additional support is installed on the floor
                  surface of the Premises.

 4.      Tenant will cause its contractor to construct the improvements within
         the Premises in accordance with the construction drawings and
         specifications previously approved by Landlord.

         Landlord retains the right to approve said general contractor's
         subcontractors and insist that said general contractor use the
         building's approved electrical, sprinkler and mechanical subcontractor.
         In all cases, Tenant will be required to adhere to Building standard
         requirements for construction and standard operating procedures and to
         indoor air quality procedures throughout the construction period.
         Tenant's General Contractor will be required to perform the following
         procedures during construction:

         Prior to starting construction, Tenant must supply to Landlord:

         (i)      Cost estimation of buildout and bid results on Landlord's Bid
                  Breakdown format.

         (ii)     Complete set of Architectural and Engineered drawings (i.e.
                  Structural, Mechanical, Fire Protection and Electrical)
                  stamped "Release for Construction" by an architect registered
                  in the State of Georgia. Landlord will have seven (7) business
                  days to review and approve drawings prior to start of
                  construction.

         (iii)    Schedule for project.

         (iv)     Certificate of Insurance and Builders Risk Policy naming
                  Landlord and COMPASS Management and Leasing, Inc. as
                  additional insureds.


                                  Exhibit "D"
                                  -----------
                                  Page 2 of 3
<PAGE>
 
         (v)      Performance and Payment Bond from general contractor and all
                  subcontractors.

         (vi)     Copy of Building Permit.

         (vii)    Letter of Indemnification holding Landlord and COMPASS
                  harmless for any and all claims resulting from construction,
                  including In-Door Air Quality.

         (viii)   Copy of Contract between Tenant and all contractors, including
                  architectural and MEP design firms.

         (ix)     List of all contractors who will be working on the project for
                  Landlord's review and approval.

         During construction, Tenant will:

         (i)      Hold weekly job meetings and notify Landlord of time and
                  place.

         (ii)     Provide Landlord copies of all executed change orders
                  affecting the cost of the project.

         (iii)    Notify Landlord of all job safety meetings.

         (iv)     Adhere to all Building Rules, Regulations and Requirements for
                  construction.

         Close-Out of Construction:

         (i)      Tenant will provide to Landlord:

                  (a)      Copy of Certificate of Occupancy.
                  (b)      Certified Test and Balance Report from Independent
                           Test and Balance Company.
                  (c)      Fire Alarm Certification Letter.
                  (d)      Final Lien Waivers from all architect, engineers
                           vendors, contractors and material suppliers.
                  (e)      Letter from Tenant certifying that all contractors
                           and vendors have been paid in full and that there are
                           no outstanding claims.
                  (f)      Signed-off punchlist from architect and Tenant.
                  (g)      Architectural and MEP As-Built Drawings on cad disk.
                  (h)      Sign-off from Landlord that all public areas and
                           other areas the contractors used during the course of
                           construction are free from damages as a result of
                           construction. The Landlord reserves the right to stop
                           all work if Tenant or it's construction manager or
                           it's contractor fails to comply with above standards.
                           The Landlord will not allow work to continue until
                           Tenant or it's manager or it's contractor comply with
                           Landlord's requirements.

         Any fee collected by Tenant's construction management service provider
         will be paid out of the Tenant Improvement Allowance. In addition,
         Landlord will pay to COMPASS Management and Leasing, Inc. a
         construction management fee of one percent (1%) (not to exceed
         $10,000.00) of the total cost of construction which will be deducted
         from the first installment of the Tenant Improvement Allowance.

5.       Landlord and Tenant hereby appoint COMPASS Management and Leasing, Inc.
         to perform all construction management services for the work to be
         performed in the Premises as described in Paragraph 4.

6.       Tenant shall not make any alterations, additions or improvements in or
         to the Premises without Landlord's prior written consent, which consent
         shall not be unreasonably withheld. Except for construction as provided
         in Paragraph 4 hereof, the Premises are delivered to Tenant "as is"
         without any warranty or representation whatsoever. Any alterations,
         additions or improvements requested by Tenant and approved by Landlord
         shall be performed (i) by Tenant's contractor or another contractor
         approved by Landlord, (ii) in a good and workmanlike manner, and (iii)
         in accordance with all applicable laws, ordinances, rules and
         regulations of governmental authorities having jurisdiction over the
         Premises.

7.       Any approval by Landlord of or consent by Landlord to any plans,
         specifications or other items to be submitted to and/or reviewed by
         Landlord pursuant to this Lease shall be deemed to be strictly limited
         to an acknowledgment of approval or consent by Landlord thereto and,
         whether or not the work is performed by Landlord or by Tenant's
         contractor, such approval or consent shall not constitute the
         assumption by Landlord of any responsibility for the accuracy,
         sufficiency or feasibility of any plans, specifications or other such
         items and shall not imply any acknowledgment, representation or
         warranty by Landlord that the design is safe, feasible, structurally
         sound or will comply with any legal or governmental requirements, and
         Tenant shall be responsible for all of the same.

8.       If all or any portion of the Tenant Improvement Allowances shall not be
         used by Tenant, Landlord shall be entitled to the savings and Tenant
         shall receive no credit therefore.


                                  Exhibit "D"
                                  -----------
                                  Page 3 of 3
<PAGE>
 
                                  EXHIBIT "E"
                                  -----------

                           BUILDING STANDARD SERVICES
                           --------------------------

         Landlord shall furnish the following services to Tenant during the
Lease Term (the "Building Standard Services"):

         (a) Hot and cold domestic water and common-use restrooms and toilets at
locations provided for general use and as reasonably deemed by Landlord to be in
keeping with the first-class standards of the Building.

         (b) Subject to curtailment as required by governmental laws, rules or
mandatory regulations and subject to the design conditions set forth in
Paragraph 3(a) of Exhibit "D" attached hereto, central air conditioning in
season, at such temperatures and in such amounts as are reasonably deemed by
Landlord to be in keeping with the first-class standards of the Building. Such
air conditioning shall be furnished between 7:00 a.m. and 6:00 p.m. on weekdays
(from Monday through Friday, inclusive) and between 9:00 a.m. and 1:00 p.m. on
Saturdays, all exclusive of Holidays, as defined below (the "Building Operating
Hours"). During Building Operating Hours Landlord shall provide at Landlord's
expense permanent air conditioning and ventilating capacity for the entire
Premises sized to accommodate a cooling load of four (4) watts per square foot
with an occupancy of one (1) person per 150 usable square feet to maintain 75
degrees inside at 92 degrees dry bulb outside in Summer and 72 degrees inside at
17 degrees dry bulb outside in winter.

         The following dates shall constitute "Holidays", as that term is used
in this Lease: New Year's Day, Memorial Day, Independence Day, Labor Day,
Thanksgiving Day, Friday following Thanksgiving Day, Christmas, and any other
holiday generally recognized as such by landlords of office space in the
metropolitan Atlanta office market, as determined by Landlord in good faith. If,
in the case of any specific holiday mentioned in the preceding sentence, a
different day shall be observed than the respective day mentioned, then that day
which constitutes the day observed by national banks in Atlanta, Georgia on
account of said holiday shall constitute the Holiday under this Lease.

         (c) Electric lighting service for all public areas and special service
areas of the Building in the manner and to the extent reasonably deemed by
Landlord to be in keeping with the first-class standards of the Building.

         (d) Janitor service shall be provided five (5) days per week, exclusive
of Holidays (as hereinbelow defined), in a manner that Landlord reasonably deems
to be consistent with the first-class standards of the Building.

         (e) Security services for the Building comparable as to coverage,
control and responsiveness (but not necessarily as to means for accomplishing
same) to other similarly situated first-class, multi-tenant office buildings in
Atlanta, Georgia; provided, however, Landlord shall have no responsibility to
prevent, and shall not be liable to Tenant for, any liability or loss to Tenant,
its agents, employees and visitors arising out of losses due to theft, burglary,
or damage or injury to persons or property caused by persons gaining access to
the Premises, and Tenant hereby releases Landlord from all liability for such
losses, damages or injury.

         (f) Sufficient electrical capacity to operate (i) incandescent lights,
typewriters, calculating machines, photocopying machines and other machines of
the same low voltage electrical consumption (120/208 volts); and (ii) lighting
(277/480 volts), provided that the total rated electrical design load for said
lighting and machines of low electrical voltage shall not exceed four (4) watts
per square foot of usable area (each such rated electrical design loan to be
hereinafter referred to as the "Building Standard Rated Electrical Design
Load").

                  Should Tenant's total rated electrical design load for the
entire Premises or any portion thereof (including, but not limited to, computer
or telephone rooms) exceed the Building Standard Rated Electrical Design Load
for either low or high voltage electrical consumption, or if Tenant's electrical
design requires low voltage or high voltage circuits in excess of Tenant's share
of the Building standard circuits, Tenant will (at Tenant's expense) install
such additional circuits and associated high voltage panels and/or additional
low voltage panels with associated transformers (which additional circuits,
panels and transformers shall be hereinafter referred to as the "Additional
Electrical Equipment"). If the Additional Electrical Equipment is installed
because Tenant's low voltage or high voltage rated electrical design load
exceeds the applicable Building Standard Rated Electrical Design Load, then a
meter shall also be added (at Tenant's expense) to measure the electricity used
through the Additional Electrical Equipment.

                  The design and installation of any Additional Electrical
Equipment (or any related meter) required by Tenant shall be subject to the
prior approval of Landlord (which approval shall not be unreasonably withheld).
All expenses incurred by Landlord in connection with the review and approval of
any Additional Electrical Equipment shall also be reimbursed to Landlord by
Tenant. Tenant shall also pay on demand the actual metered cost of electricity
consumed through the Additional Electrical Equipment (if applicable), plus any
actual accounting expenses incurred by Landlord in connection with the metering
thereof.

                  If any of Tenant's electrical equipment requires conditioned
air in excess of Building standard air conditioning, the same shall be installed
by Landlord (on Tenant's behalf), and Tenant shall pay all design, installation,
metering, operating and maintenance costs relating thereto.


                                  Exhibit "E"
                                  -----------
                                  Page 1 of 2
<PAGE>
 
                  If Tenant requires that certain areas within the Premises must
operate in excess of the normal Building Operating Hours (as hereinabove
defined), the electrical service to such areas shall be separately circuited and
metered (at Tenant's expense) such that Tenant shall be billed the costs
associated with electricity consumed during hours other than Building Operating
Hours.

         (g) All Building standard fluorescent bulb replacement in all areas and
all incandescent bulb replacement in public areas, toilet and restroom areas,
and stairwells.

         (h) Non-exclusive multiple cab passenger service to the Premises during
Building Operating Hours (as hereinabove defined) and at least one (1) cab
passenger service to the floor(s) on which the Premises are located twenty-four
(24) hours per day and non-exclusive freight elevator service during Building
Operating Hours (all subject to temporary cessation for ordinary repair and
maintenance and during times when life safety systems override normal Building
operating systems) with such freight elevator service available at other times
upon reasonable prior notice and the payment by Tenant to Landlord of any
additional expense actually incurred by Landlord in connection therewith.
  
         (i) Landlord shall provide route for four (4), 4" conduits from the
telephone service point of entrance into the building premises. Tenant will
provide four (4) 4" conduits for installation by Tenant's contractor. Landlord
will not unreasonably withhold permission to provide Tenant with additional
risers.

         To the extent the services described above require electricity and
water supplied by public utilities, Landlord's covenants thereunder shall only
impose on Landlord the obligation to use its reasonable efforts to cause the
applicable public utilities to furnish same. Except for deliberate and willful
acts of Landlord, failure by Landlord to furnish the services described herein,
or any cessation thereof, shall not render Landlord liable for damages to either
person or property, nor be construed as an eviction of Tenant, nor work an
abatement of rent, nor relieve Tenant from fulfillment of any covenant or
agreement hereof. In addition to the foregoing, should any of the equipment or
machinery, for any cause, fail to operate or function properly, Tenant shall
have no claim for rebate of rent or damages on account of an interruption in
service occasioned thereby or resulting therefrom; provided, however, Landlord
agrees to use reasonable efforts to promptly repair said equipment or machinery
and to restore said services during normal business hours.





                                  Exhibit "E"
                                  -----------
                                  Page 2 of 2
<PAGE>
 
                                   EXHIBIT "F"
                                   -----------

                                    GUARANTY
                                    --------



                             [INTENTIONALLY DELETED]





                                  Exhibit "F"
                                  -----------
                                  Page 1 of 1
<PAGE>
 
                                  EXHIBIT "G"
                                  -----------

                              SPECIAL STIPULATIONS
                              --------------------


         1.       Americans With Disabilities Act.
                  --------------------------------

                  If and to the extent Landlord is required to comply with the
provisions of Title III of the Americans With Disabilities Act (the "ADA") with
respect to the common areas of the Project, Landlord agrees that it will use
reasonable efforts to comply in every material respect with the applicable
provisions of the ADA concerning the common areas of the Project; provided,
however, Landlord shall not be required to comply with the provisions of the ADA
if and to the extent the requirement of compliance therewith arises from or
extends to (a) the use or occupancy of the Project, or any portion thereof, by
any lessee, tenant, sublessee, subtenant, licensee or occupant (including
Tenant), or (b) any alteration, improvement, addition, remodeling or renovation
made, or proposed to be made, to any space in the Project leased or available
for lease (including the Premises). All costs, expenses and disbursements of
every kind and nature in connection with the Landlord's obligations under this
Section shall be included in Operating Expenses. Tenant hereby agrees that
Tenant's sole remedy against Landlord for any claim that Landlord has breached
its obligations under this Section shall be a suit for specific performance and
Tenant hereby waives any claim against Landlord for damages, whether actual,
consequential or otherwise.

         2.       Parking.
                  --------

                  (a) Landlord has allocated, and shall make available, for (and
only for) persons regularly employed by Tenant in the Premises, up to one (1)
non-reserved parking spaces per thousand feet by rentable square footage in the
Premises, or such parking to be located in the parking facilities located in the
Building, subject to the provisions set forth below. The cost of such parking
will be at the normal monthly rates established from time to time by the
Landlord, which rate is currently $95.00 per space per month, which sum shall be
due and payable on or before the first day of each month to Landlord or its
parking manager, as Landlord may direct.

                  (b) Tenant's right to the number of parking spaces allocated
to Tenant hereunder are personal to Tenant and may not be transferred to other
tenants in the Building or any other person or entity with the exception of the
potential assignees and sublessees described in Paragraph 5(b) of this Exhibit
"G". Landlord, at all times, shall have sole and exclusive control of all
parking facilities and common areas, including without limitation, driveways,
entrances and exits, sidewalks and pedestrian passageways and pylon signs, and
Landlord may at any time exclude any person from the use and occupancy thereof,
except those persons using the parking facilities in accordance with all rules
and regulations established by Landlord from time to time. Tenant agrees that
Landlord assumes no responsibility of any kind whatsoever in reference to said
automobile parking facilities or the use there of by Tenant, its employees,
agents or invitees, or by anyone else. Landlord may, at any time, and from time
to time, limit access to the parking facilities by means of attendants and/or
other devices, and may make other changes in the layout and operation of the
parking facilities including, without limiting the generality of the foregoing,
changes in locations of entrances, exits and parking spaces and changes in the
direction of traffic flow. The rental and use of all parking spaces made
available hereunder shall be subject to rules and regulations as may have been
or may be established by Landlord or its parking manager from time to time. No
delay or failure by Landlord to enforce its parking rules and regulations or its
other rights hereunder, and no waiver by Landlord of any breach thereof, shall
be deemed to be a waiver of any succeeding breach or prevent any subsequent or
other enforcement thereof by Landlord.

         3.  First Renewal Option.
             ---------------------

                  (a) As long as an event of default by Tenant has not occurred
and is continuing after applicable notice and cure periods, Landlord shall grant
and does hereby grant Tenant the option to renew (the "First Renewal Option")
the term of this Lease for a period of sixty (60) additional months (the "First
Renewal Term"). Tenant shall exercise the First Renewal Option by delivering
written notice of such election to Landlord at least twelve (12) months prior to
the expiration of the initial term of this Lease. The renewal of this Lease
shall be upon the same terms and conditions of this Lease, except (i) the Base
Rental Rate during the First Renewal Term shall be calculated based on the
prevailing Market Base Rental Rate (as hereinafter defined) at the time the
First Renewal Term commences; (ii) with the exception of the potential assignees
and sublessees described in Paragraph 5(b) of this Exhibit "G", Tenant shall not
have the right to assign its renewal rights to any sublessee of the Demised
Premises or any portion thereof or to any assignee of the Lease, nor may any
such sublessee or assignee exercise or enjoy the benefit of such renewal rights;
(iii) the leasehold improvements will be provided in their then-existing
condition at the time the First Renewal Term commences, and (iv) there shall not
be any rent abatement period and Tenant shall not be entitled to cash payment,
concessions or allowance of any nature or amount whatsoever. Notwithstanding the
foregoing, Tenant shall have no right to exercise such option to renew, and
Landlord shall have no obligation to renew this Lease, unless (A) this Lease
shall be in full force and effect upon the date of the exercise of the First
Renewal Option and upon the date of the expiration of the original term, and (B)
on the date of the exercise of the First Renewal Option and on the date of the
expiration of the original term there shall exist no event of default on the
part of Tenant under this Lease for which Landlord has given notice and which
remains uncured by Tenant after the expiration of any applicable period of grace
or cure. If Tenant shall fail to exercise the First Renewal Option within the
time permitted or conditions (A) and (B) set forth above are not entirely
satisfied, the First Renewal Option shall automatically terminate, this Lease
shall expire at the expiration of the original term and Tenant shall have no
further right thereafter to renew this Lease or to acquire any interest
whatsoever in the Demised Premises. If Tenant shall remain in possession of the
Demised Premises after the expiration of the original term without there having
been executed between


                                  Exhibit "G"
                                  -----------
                                  Page 1 of 5
<PAGE>
 
Landlord and Tenant an amendment to this Lease as contemplated by the terms of
this Section, then Tenant shall be a Tenant holding over as provided in this
Lease.

                  (b) Whenever used in this First Renewal Option, the term
"Market Base Rental Rate" shall mean the then fair market rental of the Demised
Premises as of the date of commencement of the First Renewal Term, determined in
accordance with the provisions set forth below. The fair market rental of the
Demised Premises shall mean the rental that would be agreed to by a landlord and
renewing tenant, each of whom is willing, but neither of whom is compelled, to
enter into the lease transaction. The fair market rental shall be determined on
the basis of the assumptions that (1) the Base Year shall be updated to the
first year under the First Renewal Term, and (2) the fair market rental shall
begin on the commencement date of the First Renewal Term. The fair market rental
to be determined shall take into account any existing tenant improvements and
any special uses or rights afforded to the Tenant under this Lease in connection
with the Demised Premises and the following factors: (i) rental for renewing
tenants for comparable premises in comparable Class "A" office buildings in
comparable submarkets of Atlanta, Georgia (taking into consideration, but not
limited to, use, location and/or floor level within the applicable building,
definition of rental area, quality, age and location of the applicable office
buildings); (ii) the rentable area of the premises being leased; (iii) the
length of the pertinent rental term; (iv) any tenant improvement allowance, rent
credit, moving allowance, space planning allowance or other similar inducements
given to renewing tenants or lack thereof; (v) the quality and credit worthiness
of the tenant; (vi) the expense pass-through provisions provided to such
renewing tenants; and (vii) commissions payable to brokers or lack thereof.

                  (c) If Landlord and Tenant are unable to agree upon the fair
market rental within thirty (30) days of Landlord's proposal to Tenant, the
determination of fair market rental shall be determined by three (3) appraisers
selected according to the provisions established by the American Arbitration
Association, said appraisers to have the MAI designation and a minimum of ten
(10) years experience in the Atlanta office market. The market rate will be
determined per this section following Tenant's exercise of the First Renewal
Option. The cost of arbitration shall be shared equally by Landlord and Tenant.
In the event Base Rental is to be paid in accordance with the Market Base Rental
Rate and such Market Base Rental Rate is then subject to dispute or arbitration
as provided herein, Tenant shall nevertheless pay an amount of Market Base
Rental equal to the Base Rental Rate as determined by Landlord during the
pendency of any such dispute or arbitration; provided that Landlord shall
promptly refund any amounts subsequently determined to have been overpaid by
Tenant.

         4.  Second Renewal Option.
             ----------------------

                  (a) As long as an event of default by Tenant has not occurred
and is continuing, Landlord shall grant and does hereby grant Tenant the option
to renew (the "Second Renewal Option") the term of this Lease for a period of
sixty (60) additional months (the "Second Renewal Term"). Tenant shall exercise
the Second Renewal Option by delivering written notice of such election to
Landlord at least twelve (12) months prior to the expiration of the First
Renewal Term of this Lease. The renewal of this Lease shall be upon the same
terms and conditions of this Lease, except (i) the Base Rental Rate during the
Second Renewal Term shall be calculated based on the prevailing Market Base
Rental Rate (as hereinafter defined) at the time the Second Renewal Term
commences, (ii) with the exception of the potential assignees or sublessees
described in Paragraph 5(b) of this Exhibit "G", Tenant shall have no option to
renew this Lease beyond the expiration of the Second Renewal Term, and (iii)
Tenant shall not have the right to assign its renewal rights to any sublessee of
the Demised Premises or any portion thereof or to any assignee of the Lease, nor
may any such sublessee or assignee exercise to enjoy the benefit of such renewal
rights, and (iv) the leasehold improvements will be provided in their
then-existing condition at the time the Second Renewal Term commences, and there
shall not be any rent abatement period and Tenant shall not be entitled to cash
payment, concessions or allowance of any nature or amount whatsoever.
Notwithstanding the foregoing, Tenant shall have no right to exercise such
option to renew, and Landlord shall have no obligation to renew this Lease,
unless (A) this Lease shall be in full force and effect upon the date of the
exercise of the Second Renewal Option and upon the date of the expiration of the
First Renewal Term, and (B) on the date of the exercise of the Second Renewal
Option and on the date of the expiration of the First Renewal Term there shall
exist no event of default on the part of Tenant under this Lease for which
Landlord has given notice and which remains uncured by Tenant after the
expiration of any applicable period of grace or cure. If Tenant shall fail to
exercise the Second Renewal Option within the time permitted or conditions (A)
and (B) set forth above are not entirely satisfied, the Second Renewal Option
shall automatically terminate, this Lease shall expire at the expiration of the
First Renewal Term and Tenant shall have no further right thereafter to renew
this Lease or to acquire any interest whatsoever in the Demised Premises. If
Tenant shall remain in possession of the Demised Premises after the expiration
of the First Renewal Term without there having been executed between Landlord
and Tenant an amendment to this Lease as contemplated by the terms of this
Section, then Tenant shall be a Tenant holding over as provided in this Lease.

                  (b) Whenever used in this Second Renewal Option, the term
"Market Base Rental Rate" shall mean the then fair market rental of the Demised
Premises as of the date of commencement of the Second Renewal Term, determined
in accordance with the provisions set forth below. The fair market rental of the
Demised Premises shall mean the rental that would be agreed to by a landlord and
renewing tenant, each of whom is willing, but neither of whom is compelled, to
enter into the lease transaction. The fair market rental shall be determined on
the basis of the assumptions that (1) the Base Year shall be updated to the
first year under the Second Renewal Term or if the commencement of the Second
Renewal Term falls in the 4th quarter of a year then the Base Year shall be
updated to the next full calendar year under the Second Renewal Term, and (2)
the fair market rental shall begin on the commencement date of the Second
Renewal Term. The fair market rental to be determined shall take into account
any existing tenant improvements and any special uses or rights afforded to the
Tenant under this Lease in connection with the Demised Premises the following
factors: (i) rental for renewing tenants for comparable premises in comparable
Class "A" office buildings in comparable submarkets of Atlanta, Georgia (taking
into consideration, but not limited to, use, location and/or floor level within
the applicable building, definition of rental area, quality, age and location of
the applicable office buildings); (ii) the rentable area of the premises being
leased; (iii) the length of the pertinent rental term; (iv) any tenant
improvement allowance, rent


                                  Exhibit "G"
                                  -----------
                                  Page 2 of 5
<PAGE>
 
credit, moving allowance, space planning allowance or other similar inducements
given to renewing tenants; (v) the quality and credit worthiness of the tenant;
(vi) the expense pass-through provisions provided to such renewing tenants; and
(vii) commissions payable to brokers

                  (c) If Landlord and Tenant are unable to agree upon the fair
market rental within thirty (30) days of Landlord's proposal to Tenant, the
determination of fair market rental shall be determined by three (3) appraisers
selected according to the provisions established by the American Arbitration
Association, said appraisers to have the MAI designation and a minimum of ten
(10) years experience in the Atlanta office market. The market rate will be
determined per this section following Tenant's exercise of the Second Renewal
Option. The cost of arbitration shall be shared equally by Landlord and Tenant.
In the event Base Rental is to be paid in accordance with the Market Base Rental
Rate and such Market Base Rental Rate is then subject to dispute or arbitration
as provided herein, Tenant shall nevertheless pay an amount of Market Base
Rental equal to the Base Rental Rate as determined by Landlord during the
pendency of any such dispute or arbitration; provided that Landlord shall
promptly refund any amounts subsequently determined to have been overpaid by
Tenant.

         5. Landlord's Consent to Assignment and Subletting Requests.
            ---------------------------------------------------------

(a) Notwithstanding anything contained in Article 21 to the contrary, provided
Tenant is not in default hereunder, Landlord shall not unreasonably withhold its
consent to Tenant's request to assign this Lease or to sublease the Premises. In
determining the reasonableness of Landlord's approval of or failure to consent
to Tenant's assignment of this Lease or the subleasing of the Premises, Landlord
may take into consideration all relevant factors surrounding the proposed
sublease and assignment, including without limitation, the following:

          (i)       the business reputation of the proposed assignee or
                    subtenant and its partners, officers, directors, and
                    stockholders;

          (ii)      the nature of the business and the proposed use of the
                    Premises by the proposed assignee or subtenant;

          (iii)     the financial condition of the proposed assignee or
                    subtenant;

          (iv)      the effect that the proposed assignee or subtenant would
                    have on the operations and maintenance of the Building and
                    Landlord's investment therein;

          (v)       whether or not the assignee or subtenant is reputable and of
                    a kind customarily found in a "Class A" office building;

          (vi)      whether or not the proposed assignee or subtenant is
                    presently a tenant (or subsidiary, affiliate or parent of a
                    tenant) in the Building;

          (vii)     restrictions, if any, contained in other leases or
                    agreements affecting the Building;

          (viii)    the extent to which the proposed subtenant or assignee and
                    Tenant provide Landlord with assurances reasonably
                    satisfactory to Landlord as to the satisfaction of Tenant's
                    obligations hereunder, including the payment of rent;

          (ix)      restrictions, if any, imposed by the holder of any mortgage
                    encumbering the Building or any portion thereof; and

          (x)       whether or not the proposed assignee or subtenant is willing
                    to agree in the assignment of lease agreement or sublease
                    agreement, as the case may be, to comply at its expense,
                    with all laws, ordinances, orders, directions, requirements,
                    rules and regulations of all governmental authorities, then
                    in force and which may thereafter be in force, which impose
                    any duty on Landlord or the assignee or subtenant, as the
                    case may be, with respect to the use, occupancy or
                    alteration of the Premises or any portion thereof.

         (b) Notwithstanding anything contained in Article 21 to the contrary,
provided Tenant is not in default hereunder after notice and cure periods, if
any, Tenant shall have the right, upon at least ten (10) days' prior written
notice to Landlord and the delivery of the executed copy of the proposed
assignment agreement or sublease as provided below, to assign this Lease or to
sublet all or any portion of the Premises to any entity resulting from a merger
or consolidation with Tenant, (2) any entity succeeding to substantially all the
business and assets of Tenant at the Premises, (3) any subsidiary or parent of
Tenant, or (4) any entity resulting from the reorganization of Tenant outside of
a bankruptcy organization. In such case Landlord shall not have any right to
recapture any portion of the Premises or share in any excess rents.

         6. Cap on Controllable Operating Expenses. For purposes of calculating
Tenant's Additional Rental pursuant to Article 8 of the Lease, Landlord and
Tenant hereby agree that, commencing with the first full calendar year of the
Lease Term, Operating Expenses (except for Uncontrollable Costs, as hereinafter
defined) shall be deemed not to increase by more than four percent (4%) from one
calendar year to the next calendar year, regardless of any actual increases in
Operating Expenses; provided, however, in the event that in any calendar year
any such increase in Operating Expenses is in fact greater than the Operating
Expense Cap (any such increase in excess of the Operating Expense Cap being
hereinafter collectively referred to as the "Carryover Percentage"), Landlord
shall have the right to add all of the Carryover

                                  Exhibit "G"
                                  -----------
                                  Page 3 of 5
<PAGE>
 
Percentage (or such portion thereof as will not produce a total increase in
Operating Expenses in excess of the Operating Expense Cap) to the increases in
Operating Expenses occurring over any of the following years of the Lease Term
in which such increases in Operating Expenses are less than the Operating
Expense Cap, on a cumulative basis until all such Carryover Percentages have
been used to increase Operating Expenses for purposes of calculating Tenant's
Additional Rental payable pursuant to Article 8 of the Lease. For example, if
the actual increase in Operating Expenses during the second calendar year of the
Lease Term is ten percent (10%) and if, for purposes of this example, the
Operating Expense Cap is eight percent (8%) (thus creating a Carryover
Percentage of two percent (2%), which may be carried forward to future years by
Landlord), and if in the third calendar year of the Lease Term the actual
increase in the Operating Expenses is six percent (6%), then during the third
calendar year of the Lease Term Operating Expenses shall be deemed to increase
by eight percent (8%), such eight percent (8%) increase arising from adding the
six percent (6%) increase in Operating Expenses which occurred in the third
calendar year to the two percent (2%) Carryover Percentage from the second
calendar year. The foregoing provisions of this Section notwithstanding, Taxes,
all utility costs and expenses, including, without limitation, those for
electricity and other fuels and forms of power or energy, water charges, sewer
and waste disposal, and the cost of all casualty, liability and other insurance
applicable to the Project and Landlord's personal property used in connection
with the Project (all of the foregoing are herein collectively referred to as
"Uncontrollable Costs") shall not be subject to any limitation or cap, and,
accordingly, the total dollar increase in Operating Expenses, and Tenant's
Additional Rental payable pursuant to Article 8 of the Lease, for any and each
calendar year during the Lease Term shall be calculated without any limitation
or cap on Uncontrollable Costs.

         7. Tenant's Generator and Fuel Storage Tank. Tenant may install one (1)
generator up to 750 kw, subject to Landlord's written approval (which approval
shall not be unreasonably withheld or delayed) of design and installation plans
and specifications therefor. In addition, Tenant is to be provided throughout
the Lease Term a pathway for conduits running from such generator location to
the Premises. Tenant shall be responsible for all costs associated with
constructing dedicated space for the supplemental generator and fuel storage
tank, associated transfer pumps and day storage tank. All costs associated with
preparing such location and the installation of such new tank will be the
responsibility of Tenant. Other than in cases of emergency, Tenant shall have
the right to exercise the generator on a weekly basis with Landlord approved
times and duration, which approval shall not be unreasonably withheld or
delayed. Tenant's fuel storage tank up to a maximum of 2,000 gallons, and
associated transfer pumps shall be located in an area designated by Landlord,
and in accordance with Landlord's written approval as aforesaid. The location of
any penetrations required for the installation of Tenant's equipment shall be
x-rayed and said location approved by Landlord's representative before the
penetration is made.

        8. Loading Dock Area. Tenant's future generator shall be in compliance
with all noise control ordinances and shall have muffler and sound absorbers
built in. Tenant agrees to use its best efforts to abate any unreasonable noises
produced by Tenant's generator at all times during the Lease Term. The Generator
Area shall be constructed in a manner which is compatible in appearance with the
surrounding interior portions of the Loading Dock area of the Building and shall
be constructed in compliance with, and throughout the Lease Term and shall
remain in compliance with, all terms of this Lease during the Lease Term; prior
to construction thereof Tenant shall obtain Landlord's approval, not to be
unreasonably withheld or delayed, as to the manner and schedule for installing
and constructing such Generator Area. Tenant agrees to maintain free of
obstruction all sidewalks in its use and construction of the Generator Area,
and, if necessary in Landlord's sole discretion, Tenant, at its sole cost and
expense, shall provide alternate sidewalk space for other tenants of the
Building. Tenant shall be permitted to terminate the products of combustion
exhaust. Tenant is responsible for taking the necessary reasonable measures to
reduce the sound transmissions caused by Tenant's equipment between the Premises
and the adjacent premises. In addition, each engine generator set including
radiator, shall be installed in a weatherproof, walk-around type, sound
attenuating enclosure which shall keep the sound pressure to no more than 85 dba
as measured at three (3) feet from any side or top, under all operating
conditions.

        9. Antenna/Satellite Dish Installation. Landlord hereby grants Tenant
the right to use and have access to the roof of the Building, for the
installation, maintenance, repair and removal of an antenna and/or satellite
dish. The precise location of such antenna/satellite dish and installation
thereof shall be approved by Landlord after Landlord's review of Tenant's
specifications, which approval shall not be unreasonably withheld based on
Landlord's standard review criteria. Tenant hereby agrees to install, maintain
and repair such antenna/satellite dish so as not to penetrate the roof membrane
and in an otherwise good and workmanlike manner, to secure all permits required
for the installation and operation thereof, and to keep the Building free of any
liens which might arise therefrom. Upon and following installation of a rooftop
satellite dish and/or antenna, Tenant shall pay Landlord a monthly fee of
$150.00 per month payable on the same date Rent is due hereunder for as long as
a satellite dish and/or antennae remain installed on the roof of the Building.
Tenant hereby indemnifies Landlord from and against any claims against Landlord
for personal injury or property damage arising from the use, operation,
maintenance, repair and removal of the antenna/satellite dish other than any
claim arising from the acts or omissions of the Landlord. Upon the expiration or
earlier termination of the Lease, Tenant shall remove the antenna/satellite dish
and shall restore the installation location to substantially the same condition
as existed prior to the installation of such equipment, ordinary wear and tear
and insured casualty loss excepted. Tenant acknowledges and agrees that nothing
contained herein shall be deemed to grant to Tenant any independent right to
access of the roof of the Building. All access to the roof shall under all
circumstances be made through and in conjunction with Landlord or its agents and
shall be subject to such reasonable controls and restrictions as Landlord may
impose from time to time. Tenant agrees that it will be responsible for
obtaining all licenses and permits necessary to operate any antenna/satellite
dish installed on the roof of the Building and will not use such equipment (or
any transmissions therefrom) to interfere with the transmissions or frequencies
of other rooftop antenna/satellite dishes currently installed on the roof of the
Building.

        10. Supplemental HVAC. Tenant may install up to 100 tons of HVAC during
the term of this Lease. Landlord does not supply chilled water on a 24-hour per
day, 7 days a week basis. For Tenant's 24-hour, 7 days a week HVAC requirement,
Tenant must install a supplemental HVAC unit, subject to mutual agreement
between Landlord and Tenant based on Tenant's final specifications and
Landlord's

                                  Exhibit "G"
                                  -----------
                                  Page 4 of 5
<PAGE>
 
approval shall not be unreasonably withheld or delayed. Any and all electrical
power consumed by tenant through a supplemental HVAC unit(s) must be separately
metered (at Tenant's expense) and all will be charged monthly to Tenant as Rent
at Landlord's average rate for electricity consumption.

        11.   Miscellaneous.

              (a) Landlord acknowledges that Tenant's business to be conducted
in the Premises requires the installation in the Premises of certain
communications equipment by telecommunications customers of Tenant ("Customers")
in order for such Customers to interconnect with Tenant's Terminal facilities.
Landlord agrees that no consent shall be required for any license agreement or
"co-location agreement" between Tenant or any such Customer for the purposes of
permitting such a telecommunications connection, so long as (i) such Customer
agrees in writing to comply with all obligations of Tenant under this Lease to
the extent relating to the portion of the Premises in question, and (ii) each
such license or co-location agreement is in writing, and is consistent with the
provisions of this Lease. Co-location shall not be deemed under any
circumstances, a sublet or assignment of the Premises.

              (b) Landlord and Tenant agree that Tenant's communication, HVAC,
electrical and other various equipment will require Tenant to use Building
shafts, risers, chases, utility entrances, equipment rooms, and distribution
areas of conduits between the Premises and other parts of the Building
(excluding the roof). Tenant shall be afforded the right to use where available,
and or construct conduits to connect Tenant's equipment.

              (c) Tenant shall have the right to utilize and/or install four (4)
four inch (4") conduits from the telephone service point of entrance into the
Building to designated areas within the Tenant's Premises. Landlord will
cooperate in locating points of entry to provide redundancy of access for
telecommunications services and providers to the Building.

              (d) Landlord shall permit Tenant, and Tenant's agents to enter the
Premises no later than February 1, 1999 so that Tenant may construct its
improvements, in accordance with Exhibit "D" of the Lease. Tenant's entry prior
to the Term Commencement Date shall constitute a license only and not a lease
and such license shall be conditioned upon.

              (e) Tenant shall be afforded access to the Building's electrical
supply to obtain a minimum of 500 kilowatts of power to the Premises. Landlord
warrants the building has sufficient capacity to provide at least 500 kilowatts
of power during the Term. Tenant shall have the right at any time during the
Term to upgrade the Building's electrical service, subject to Landlord's review
and approval.


                                  Exhibit "G"
                                  -----------
                                  Page 5 of 5
<PAGE>
 
                                   EXHIBIT "H"
                                   -----------

             SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT
             -------------------------------------------------------

        THIS SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT
(hereinafter referred to as this "Agreement"), made as of the ____ day of
__________________, 19__, by and among
____________________________________________________ (hereinafter referred to as
"Lender") under the Loan Documents (as defined below), THE EQUITABLE LIFE
ASSURANCE SOCIETY OF THE UNITED STATES, a New York corporation (hereinafter
referred to as "Landlord") and ______________________________, a
___________________________ corporation (hereinafter referred to as "Tenant").


                              W I T N E S S E T H:
                              --------------------

        WHEREAS, Lender is to be the owner and holder of that certain note (the
"Note") of the Landlord and a first-in-priority deed to secure debt and security
agreement more particularly described on Exhibit "A" annexed hereto (said deed
to secure debt and security agreement, as it may be amended, increased, renewed,
modified, consolidated, replaced, combined, substituted, severed, split, spread
or extended, being herein called the "Security Deed", and the Note, Security
Deed and all other documents and instruments evidencing, securing or otherwise
relating to the loan which is the subject of the Note and the Security Deed are
collectively referred to herein as the "Loan Documents") covering certain real
property more particularly described on Exhibit "B" annexed hereto (the
"Property"); and

        WHEREAS, Tenant is the tenant under a certain lease agreement to be made
by Landlord, which lease agreement (including any modifications or amendments
thereof) and the portion of the Property therein leased (the "Demised Premises")
are more particularly described on Exhibit "C" annexed hereto (as such lease
agreement may hereafter be amended, modified or supplemented by written
agreement, from time to time, among Landlord and Tenant and consented to in
writing by Lender, the "Lease"); and

        WHEREAS, Tenant, Landlord and Lender desire to confirm their
understanding with respect to the Lease and the Security Deed.

        NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, the receipt and sufficiency of which are hereby acknowledged,
the parties hereto agree as follows:

         1. Non-Disturbance. So long as Tenant is not in default (beyond any
period given Tenant to cure such default) in the payment of base rental or
additional rental or in the performance of any of the terms, covenants or
conditions of the Lease on Tenant's part to be performed: (a) provided Tenant
attorns as provided for in Paragraph 2 below, Tenant's possession or occupancy
of the Demised Premises and Tenant's rights and privileges under the Lease, or
any extensions or renewals thereof which may be effected in accordance with any
option therefor in the Lease, shall not be terminated, diminished or interfered
with by Lender in the exercise of any of Lender's rights under the Security
Deed; (b) provided Tenant attorns as provided for in Paragraph 2 below, Lender
will not join Tenant as a party defendant in any action or proceeding for the
purpose of terminating Tenant's interest under the Lease because of any default
under the Security Deed; and (c) from and after Tenant's attornment per
paragraph 2 below, Lender, its nominee, such other holder (or its nominee) or a
purchaser, as the case may be, shall be bound to Tenant under all the terms,
covenants and conditions of the Lease except as provided in paragraph 3 below.

         2. Attornment. If (a) any proceedings are brought for the foreclosure
of the Security Deed or (b) the Property is conveyed by deed in lieu or
assignment in lieu of foreclosure (or similar device), Tenant shall attorn to
and recognize the Lender [or any other holder of the Note or its nominee], its
nominee, or such purchaser, as the case may be, as the landlord under the Lease
for the remainder of the term thereof, and Tenant shall perform and observe its
obligations thereunder, subject only to the terms and conditions of the Lease.
Such attornment shall be effective and self-operative without the execution of
any further instrument on the part of any of the parties hereto. Tenant agrees,
however, to execute and deliver at any time, and from time to time, upon the
request of Landlord, Lender or of any other holder of any of the indebtedness or
other obligations secured by the Security Deed or any such nominee or purchaser,
any instrument or certificate which, in its sole judgment, Landlord, Lender,
such other holder, or such nominee or purchaser, as the case may be, deems to be
necessary or appropriate in any such foreclosure proceeding or conveyance or
assignment in lieu of foreclosure (or similar device) or otherwise to evidence
such attornment. To the extent permitted by applicable law, Tenant waives the
provisions of any statute or rule of law now or hereafter in effect that may
give or purport to give it any right or election to terminate or otherwise
adversely affect the Lease or the obligations of Tenant thereunder by reason of
any foreclosure or other proceedings for enforcement of the Security Deed or the
taking of a deed or assignment in lieu of foreclosure (or similar device).

         3. Liability of Lender. If Lender [or any other holder of the Note or
its nominee] or its nominee shall succeed to the interests of Landlord under the
Lease in any manner, or if any purchaser acquires the Property or any part
thereof including the Demised Premises upon any foreclosure of the Security Deed
or by a conveyance or assignment in lieu of such foreclosure (or similar
device), Lender, its nominee, such other holder [or its nominee], or such
purchaser, as the case may be, shall have the same remedies by entry, action, or
otherwise in the event of any default by Tenant (beyond any period given Tenant
to cure such default) in the payment of base rental or additional rental or in
the performance of any of the terms, covenants and conditions of the Lease on
Tenant's part to be performed that Landlord had or would have had if Lender, its
nominee, such other holder [or its nominee] or such purchaser, as the case may
be, had not succeeded to the interest of Landlord. Except as herein provided,
from and after such attornment, Lender, its nominee, such other holder [or its
nominee] or such purchaser, as the case may be, shall be bound to Tenant under
all the terms, covenants and conditions of the Lease. Except as herein provided,
Tenant shall, from and after the succession to the interest of Landlord under
the Lease by Lender, its nominee, or such other holder [or its nominee] or such
purchaser, as the case may be, have the same remedies against Lender, its
nominee, such other holder [or its nominee] or such purchaser, as the case may
be, for the breach of any agreement contained in the Lease that Tenant might
have had under the Lease against Landlord if Lender, its nominee, such other
holder [or its nominee] or such purchaser, as the case may be, had not succeeded
to the interest of Landlord; provided, however, that, except for Landlord
defaults for which Tenant has given Landlord and Lender written notice, Lender,
its nominee, such other holder [or its nominee] or such purchaser, as the case
may be, shall not be:

                                  Exhibit "H"
                                  -----------
                                  Page 1 of 8
<PAGE>
 
               (i) obligated to cure any defaults under the Lease of any prior
         landlord (including Landlord);

               (ii) liable for any act or omission of any prior landlord
         (including Landlord);

               (iii) subject to any offsets or defenses which Tenant might have
         against any prior landlord (including Landlord) except as set forth in
         Article 1, subparagraph (l) of the Lease;

               (iv) bound by any base rental or additional rental which Tenant
         might have paid for more than the current month to any prior landlord
         (including Landlord);

               (v) bound by any amendment or modification of the Lease made
         without Lender's prior written consent;

               (vi) bound by any warranty or representation of any prior
         landlord (including Landlord) relating to work performed by any prior
         landlord (including Landlord) under the Lease;

               (vii) liable to Tenant for construction or renovation, or delays
         in construction or restoration, of the improvements situated or to be
         situated on the Property;

               (viii) obligated to make any capital improvements to the Property
         or the Demised Premises which any prior landlord (including Landlord)
         has agreed to make but not completed or to perform or furnish any
         services not related to the possession and quiet enjoyment of the
         Demised Premises; or

               (ix) responsible for security deposits or other refundable fees
         unless paid over to Lender.

         4. No Affect on Security Title and Lien of Security Deed. Nothing
herein contained shall in any way impair or affect the security title and lien
created by the Security Deed except as may be specifically set forth herein.
Nothing herein contained is intended, nor shall be construed, to abridge or
adversely affect any right or remedy of Landlord under the Lease in the event of
any default by Tenant (beyond any period given Tenant to cure such default) in
the conditions of the Lease on Tenant's part to be performed.

         5. Subordination. Tenant hereby covenants and agrees that the Lease,
together with all rights, title, interests, estates, options, liens and charges
created thereby, is hereby expressly made, now is and shall at all times
continue to be subject, subordinate and inferior in all respects to the Loan
Documents, the Security Deed, the Note, all sums advanced under the Note, and
all other documents and instruments evidencing or securing (or to evidence or
secure) the indebtedness evidenced by the Note and secured by the Security Deed
and to all amendments, consolidations, extensions, replacements, modifications,
renewals, recastings, refinancings, transfers and assignments thereof, subject
to the terms of this Agreement. Tenant, upon request, shall execute and deliver
any certificate or other instrument whether or not in recordable form which
Lender may request to perfect, confirm or effectuate said subordination. The
Loan Documents shall be superior to the right, title, interest and estate of
Tenant in and to the Demised Premises by virtue of the Lease. The Loan Documents
may be amended from time to time without the consent of Tenant. Landlord shall
be named Tenant's attorney in fact in the event Tenant does not execute and
deliver such instruments in a timely fashion.

         6. Notices. Any notice or communication required or permitted hereunder
shall be given in writing, hand delivered, sent by any overnight courier service
providing dated evidence of delivery, or sent by United States mail, postage
prepaid, registered or certified mail, return receipt requested, addressed as
set forth on Exhibit "D" annexed hereto, or to such other address(es) or in care
of such other person(s) as hereafter shall be designated in writing by the
applicable party sent in the manner in this Paragraph 6 provided and shall be
deemed to have been given as of the date of receipt. Rejection or other refusal
to accept or inability to deliver because of changed address of which no notice
has been received shall constitute receipt.

         7. Default by Landlord. So long as the Security Deed remains
outstanding and unsatisfied, Tenant will mail or deliver to Lender, at the
address and in the manner herein provided, a copy of all notices permitted or
required to be given to Landlord by Tenant under and pursuant to the terms and
provisions of the Lease. In addition thereto, so long as the Security Deed
remains outstanding and unsatisfied, Tenant will mail or deliver to Lender, at
the address and in the manner hereinabove provided, written notice of any
default or claimed default of Landlord under the Lease (whether or not Tenant is
obligated under the Lease to give written notice thereof to Landlord). If
Landlord shall fail to cure any default within the time prescribed by the Lease,
Tenant shall give further notice of such fact to Lender. At any time before the
rights of Landlord shall have been forfeited or adversely affected because of
any default of Landlord, or within the time permitted Landlord for curing any
default under the Lease as therein provided (but not less than sixty (60) days
from the receipt of notice), Lender may, but shall have no obligation to, pay
any taxes and assessments, make any repairs and improvements, make any deposits
or do any other act or thing required of Landlord by the terms of the Lease, and
all payments so made and all things so done and performed by Lender shall be as
effective to prevent the rights of Landlord from being forfeited or adversely
affected because of any default under the Lease as the same would have been if
done and performed by Landlord. Tenant agrees that notwithstanding any
provisions of the Lease, no notice of cancellation or abatement shall be
effective unless Lender has received notice as herein provided, and Lender has
failed within sixty (60) days of its receipt of such notice to cure the default,
or if the default cannot be cured within sixty (60) days, has failed to commence
and diligently prosecute the curing of the default (which may include, but not
be limited to, commencement of foreclosure proceedings, if necessary to effect
such cure) which gave rise to such right of cancellation or abatement.

         8. Limited Liability of Lender. Anything herein or in the Lease to the
contrary notwithstanding, in the event that Lender [or any other holder of the
Note or its nominee] or its nominee shall succeed to the interest of the
Landlord under the Lease (any of the foregoing being herein referred to as the
"Successor"), the Successor shall have no obligation, nor incur any liability,
beyond its then interest, if any, in the Property and Tenant shall look
exclusively to such interest of the Successor, if any, in the Property for the
payment and discharge of any obligations imposed upon the Successor hereunder or
under the Lease and the Successor is hereby released or relieved of any other
liability hereunder and under the Lease. Tenant agrees that with respect to any
judgment which may be obtained or secured by Tenant against the Successor,
Tenant shall look solely to the

                                  Exhibit "H"
                                  -----------
                                  Page 2 of 8
<PAGE>
 
estate or interest owned by the Successor in the Property and Tenant will not
collect or attempt to collect any such judgment out of any other assets of the
Successor. In no event shall Successor be liable to Tenant nor shall any
interest of Successor in the Property be subject to execution by Tenant, for any
indirect, special or consequential damages. 9. Satisfaction of Lease
Requirements. Tenant agrees that this Agreement satisfies any condition or
requirement in the Lease relating to the granting of a non-disturbance agreement
with respect to the Security Deed. Tenant further agrees that in the event there
is any inconsistency between the terms and provisions of this Agreement and the
terms and provisions of the Lease, the terms and provisions of this Agreement
shall be controlling.

         10. Modifications; Binding Effect. This Agreement may not be modified
orally or in any manner other than by an agreement in writing signed by the
parties hereto or their respective successors in interest. The term "Landlord",
as used herein, shall mean and include the Landlord under the Lease and any
successor landlord under the Lease up to and including any landlord succeeding
to the position of Landlord prior to and other than Lender. This Agreement shall
inure to the benefit of, and be binding upon, the parties hereto, their legal
representatives, successors and assigns, and any purchaser or purchasers at
foreclosure of the Property, and its or their respective heirs, personal
representatives, successors and assigns.

         11. Assignment of Rents. Tenant acknowledges that it has notice that
the Landlord's interest under the Lease and the rent and all other sums due
thereunder have been assigned to Lender as part of the security for the
indebtedness secured by the Security Deed, and Tenant expressly consents to such
assignment. In the event that Lender notifies Tenant of an event of default
under the Security Deed and demands that Tenant pay rent and all other sums due
under the Lease to Lender, Tenant agrees that it shall pay rent and all other
sums due under the Lease directly to Lender.

         12. Miscellaneous. This Agreement shall be governed by and construed
under the laws of the State of Georgia. If any of the terms of this Agreement or
the application thereof to any person or circumstances shall to any extent be
invalid or unenforceable, the remainder of this Agreement or the application of
any such terms to any person or circumstances other than those as to which it is
invalid or unenforceable shall not be affected thereby, and each term of this
Agreement shall be valid and enforceable to the fullest extent permitted by law.

         13. Exhibits. All exhibits attached hereto are by this reference
incorporated fully herein, and the term "this Agreement" shall include all such
exhibits.

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement
under seal as of the date first above written.

                                    "LENDER":

                                    ----------------------------------

Signed, sealed and                  ----------------------------------
delivered in the presence of:

                                    By:
- ------------------------------         -------------------------------
Witness                                    Title:
                                                 ---------------------
                                    Attest:
- ------------------------------             ---------------------------
Notary Public
                                           Title:
                                                 ---------------------

                                             [CORPORATE SEAL]




                       [SIGNATURES CONTINUE ON NEXT PAGE]



                                  Exhibit "H"
                                  -----------
                                  Page 3 of 8
<PAGE>
 
                   [SIGNATURES CONTINUED FROM PREVIOUS PAGE]



                                    "LANDLORD":

                                    ----------------------------------

Signed, sealed and                  ----------------------------------
delivered in the presence of:

                                    By:
- ------------------------------         -------------------------------
Witness                                    Title:
                                                 ---------------------
                                    Attest:
- ------------------------------             ---------------------------
Notary Public
                                           Title:
                                                 ---------------------

                                             [CORPORATE SEAL]


                                    "TENANT":

                                    ----------------------------------

Signed, sealed and                  ----------------------------------
delivered in the presence of:

                                    By:
- ------------------------------         -------------------------------
Witness                                    Title:
                                                 ---------------------
                                    Attest:
- ------------------------------             ---------------------------
Notary Public
                                           Title:
                                                 ---------------------

                                             [CORPORATE SEAL]



                                  Exhibit "H"
                                  -----------
                                  Page 4 of 8
<PAGE>
 
                                   EXHIBIT "A"
                                   -----------

                          DESCRIPTION OF SECURITY DEED
                          ----------------------------


         Deed to Secure Debt and Security Agreement executed by
________________________ in favor of _________________________ dated
_________________________________, recorded in Deed Book _____________,page
_____________, Fulton County, Georgia.






                                  Exhibit "H"
                                  -----------
                                  Page 5 of 8
<PAGE>
 
                                   EXHIBIT "B"
                                   -----------

                         (LEGAL DESCRIPTION OF PROPERTY)
                         -------------------------------






                                  Exhibit "H"
                                  -----------
                                  Page 6 of 8
<PAGE>
 
                                   EXHIBIT "C"
                                   -----------

                    DESCRIPTION OF LEASE AND DEMISED PREMISES
                    -----------------------------------------

         That certain Lease Agreement (the "Lease") between
_______________________ and _______________________________, dated
_________________, 19__.  "Demised Premises" shall have the same meaning as
defined in the Lease.








                                  Exhibit "H"
                                  -----------
                                  Page 7 of 8
<PAGE>
 
                                   EXHIBIT "D"
                                   -----------

                                NOTICE ADDRESSES
                                ----------------

The address of Landlord is:
                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

The address of Lender is:

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

The address of Tenant is:

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------

                                -------------------------------------------




                                  Exhibit "H"
                                  -----------
                                  Page 8 of 8

<PAGE>
 
                                                                   EXHIBIT 10.17

================================================================================



                                 LEASE BETWEEN

                         EVERGREEN AMERICA CORPORATION

                                   LANDLORD

                                      AND

                       FOCAL COMMUNICATIONS CORPORATION
                     OF NEW JERSEY, A DELAWARE CORPORATION


                                    TENANT


================================================================================
<PAGE>
 
                                     INDEX

<TABLE>
<S>                                                                     <C>
  ARTICLE 1  -- CERTAIN TERMS..........................................   4

  ARTICLE 2  -- DEMISED PREMISES.......................................   6

  ARTICLE 3  -- PREPARATION OF THE DEMISED PREMISES....................   7

  ARTICLE 4  -- WHEN DEMISED PREMISES ARE READY FOR
                OCCUPANCY AND COMMENCEMENT DATE........................   8

  ARTICLE 5  -- RENT...................................................   8

  ARTICLE 6  -- EXPENSE ESCALATION.....................................   9

  ARTICLE 7  -- ELECTRICAL ENERGY......................................  16

  ARTICLE 8  -- VENTILATION AND AIR CONDITIONING.......................  16

  ARTICLE 9  -- LANDLORD'S OTHER SERVICES..............................  18

  ARTICLE 10 -- USE....................................................  20

  ARTICLE 11 -- ACCESS, CHANGES IN BUILDING FACILITIES, NAME...........  22

  ARTICLE 12 -- TENANT'S CHANGES.......................................  23

  ARTICLE 13 -- TENANT'S PROPERTY......................................  25

  ARTICLE 14 -- REPAIRS AND MAINTENANCE................................  26

  ARTICLE 15 -- SECURITY DEPOSIT.......................................  27

  ARTICLE 16 -- INSURANCE..............................................  27

  ARTICLE 17 -- SUBORDINATION, ATTORNMENT,
                NOTICE TO LESSOR AND MORTGAGEES........................  29

  ARTICLE 18 -- ASSIGNMENT, MORTGAGING, SUBLETTING.....................  31

  ARTICLE 19 -- COMPLIANCE WITH LAWS AND REQUIREMENTS OF PUBLIC
                AUTHORITIES: RULES & REGULATIONS.......................  33

  ARTICLE 20 -- QUIET ENJOYMENT........................................  34

  ARTICLE 21 -- NON-LIABILITY & INDEMNIFICATION........................  34

  ARTICLE 22 -- DESTRUCTION AND DAMAGE.................................  35

  ARTICLE 23 -- EMINENT DOMAIN.........................................  36

  ARTICLE 24 -- SURRENDER..............................................  38

  ARTICLE 25 -- CONDITIONS OF LIMITATION...............................  38

  ARTICLE 26 -- RE-ENTRY BY LANDLORD -- DEFAULT PROVISIONS.............  39

  ARTICLE 27 -- DAMAGES................................................  40

  ARTICLE 28 -- WAIVERS................................................  41
</TABLE> 
 

                                      -2-
<PAGE>
 
<TABLE> 
<S>                                                                     <C>  
  ARTICLE 29  -- NO OTHER WAIVERS OR MODIFICATIONS.....................  42

  ARTICLE 30  -- CURING TENANT'S DEFAULTS, ADDITIONAL RENT.............  43

  ARTICLE 31  -- NOTICES -- SERVICE OF PROCESS.........................  44

  ARTICLE 32  -- ESTOPPEL CERTIFICATE, MEMORANDUM......................  44

  ARTICLE 33  -- NO OTHER REPRESENTATIONS, CONSTRUCTION, GOVERNING
                 LAW...................................................  45

  ARTICLE 34  -- PARTIES BOUND.........................................  45

  ARTICLE 35  -- SHORING AND NOTICE OF ACCIDENTS AND DAMAGE............  46

  ARTICLE 36  -- VAULT, VAULT SPACE, AREA..............................  46

  ARTICLE 37  -- INABILITY TO PERFORM..................................  47

  ARTICLE 38  -- LIABILITY OF LANDLORD.................................  47

  ARTICLE 39  -- BROKERAGE.............................................  47

  ARTICLE 40  -- FIRST RENEWAL OPTION..................................  47

  ARTICLE 41  -- SECOND RENEWAL OPTION.................................  48

  ARTICLE 42  -- MISCELLANEOUS PROVISIONS..............................  49

  EXHIBIT A-1 -- DEMISED PREMISES......................................  51

  EXHIBIT A-2 -- EMERGENCY STAND-BY GENERATOR SPACE....................  52

  EXHIBIT A-3 -- ROOF SPACE............................................  53

  EXHIBIT B   -- RULES AND REGULATIONS.................................  54

  EXHIBIT C   -- TENANT'S WORK.........................................  58

  EXHIBIT C-1 -- BUILDING RULES AND REGULATIONS FOR TRADES CONDUCTING
                 OPERATIONS IN THE BUILDING............................  59

  EXHIBIT C-2 -- INSURANCE REQUIREMENTS FOR TRADES CONDUCTING
                 OPERATIONS IN THE BUILDING............................  61

  EXHIBIT D   -- CLEANING STANDARDS....................................  62

  EXHIBIT E   -- SUBORDINATION, NON DISTURBANCE AND ATTORNMENT
                 AGREEMENT.............................................  68
</TABLE>

                                      -3-
<PAGE>
 
                                 OFFICE LEASE

AGREEMENT OF LEASE, made the 19th day of February, 1999, between EVERGREEN
AMERICA CORPORATION, A New Jersey Corporation, (hereinafter called the
"Landlord") and FOCAL COMMUNICATIONS CORPORATION OF NEW JERSEY, A DELAWARE
CORPORATION "Tenant", as hereinafter defined.

                          ARTICLE 1 -- CERTAIN TERMS

     1.01  The following terms shall have the meanings set forth opposite each
of them, provided that if "None" is set forth opposite any term, then the
provision of the Lease applicable to such term shall be considered deleted and
of no force and effect.

"Tenant" --

     a corporation organized under the laws of the State of Delaware having its
     principal office at 200 N. Lasalle Street, Chicago, Illinois 60601, and
     licensed to do business in the State of New Jersey.

"Term" --

     The period beginning on the Commencement Date and ending at noon on the
     Expiration Date.

"Commencement Date" --

     March 1, 1999 or the date on which the Demised Premises are ready for
     occupancy as provided in Article 4 hereof.

"Expiration Date" --

     The last day of the calendar month in which occurs the end of a ten (10)
     year period from the Commencement Date (if the Commencement Date shall
     occur on a day other than the first day of a calendar month such period
     shall run and be measured from the first day of the calendar month
     following the Commencement Date) or ending on an earlier date on which this
     Lease may expire or be cancelled or terminated pursuant to the terms of
     this Lease.

"Fixed Rent" --

     Years One through Five (5) Five Hundred Twenty Six Thousand Three Hundred
     Twenty Five Dollars ($526,325.00) per year, payable in monthly installments
     of $43,860.42, (as adjusted in accordance with this Lease).

     Years Six (6) through Ten (10) Six Hundred Eleven Thousand Fifty Five
     Dollars ($611,055.00) per year, payable in monthly installments of
     $50,921.25 (as adjusted in accordance with this Lease).

"Building" --

     The Building located in the City of Jersey City, County of Hudson and State
     of New Jersey and known as One Evertrust Plaza, Jersey City, New Jersey.

                                      -4-
<PAGE>
 
"Demised Premises" --

     The entire seventeenth (17th) floor of the Building delineated on the floor
     plan attached hereto as Exhibit A, the total area of which is the Tenant's
     Floor Space.

"Tenant's Floor Space" --

     The total number of rentable square feet of space in the Demised Premises,
     which, for purposes of this Lease, the parties agree and stipulate is
     18,500 square feet.

"Total Building Floor Space" --

     The total number of rentable square feet of space in the Building, which,
     for purposes of this Lease, the parties agree and stipulate is 314,503
     square feet.

"Tenant's Share" --

     5.882%; which is the percentage resulting from dividing the Tenant's Floor
     Space by the Total Building Floor Space.

"Security Deposit" --
 
     See Article 15 hereof.

"Permitted Use" --

     The Demised Premises may be used for professional offices, and for the
     installation, operation and maintenance of equipment, and facilities in
     connection with Tenant's telecommunications business.

"A.C. Charge" --

     $75.00 per hour for additional air conditioning pursuant to Article 8.01
     hereof.

"H. Charge" --

     $75.00 per hour additional heating pursuant to Article 8.01 hereof.

"Broker" --

     Dolan Realty, Inc. and Grubb & Ellis which Tenant represents and warrants
     are the sole Brokers with whom it has dealt in this transaction, and based
     thereupon Landlord agrees to pay a brokerage commission in accordance with
     a separate agreement between Landlord and Brokers.

"Regular Business Hours" --

     8:00 a.m. to 6:00 p.m. Monday through Friday; 8:30 a.m. to 12:30 p.m. on
     Saturday, except where such days are observed by the Federal or the New
     Jersey State government as legal holidays, or as union holidays.

"Number of Parking Spaces" --

     Tenant shall have the right to lease up to eighteen (18) exterior parking
     spaces at additional rent of $140.00 for each parking space, payable
     monthly. Notwithstanding the foregoing, Landlord may increase the rent for
     exterior parking spaces from time to time during the term of this Lease
     after the first year of the Term of this Lease. In the event Landlord
     builds a parking structure, which will be constructed at Landlord's sole
     cost and expense, Tenant's parking shall be relocated to such parking
     structure and Tenant shall have the right to lease up to the same number of
     exterior parking spaces leased by Tenant prior to the building of the
     parking structure at additional rent as determined by Landlord for each
     parking space, payable monthly. Notwithstanding the foregoing, Landlord may
     increase the rent for parking spaces in a parking structure from time to

                                      -5-
<PAGE>
 
     time during the term of this Lease after the first year of operation of the
     parking structure.

     1.02  Electrical energy consumed by Tenant in the Demised Premises through
wall and floor outlets, for lighting and business equipment shall be purchased
by Tenant as provided in Article 7.

                         ARTICLE 2 -- DEMISED PREMISES

     2.01  Landlord hereby leases to Tenant, and Tenant hereby hires from
Landlord, the Demised Premises for the Term, for the rents hereinafter reserved
and upon and subject to the conditions (including limitations, restrictions and
reservations) and covenants hereinafter provided. Each party hereto agrees to
observe and perform all of the conditions and covenants herein contained on its
part to be observed and performed.

     2.02  The general location, size and layout of the Demised Premises are
outlined on Exhibit A-1, but Exhibit A-1 shall not be deemed to be a warranty,
representation or agreement on the part of Landlord that the Demised Premises
and the Building will be exactly as indicated on Exhibit A-1.

     2.03  Nothing herein contained shall be construed as a grant or demise by
Landlord to Tenant of the roof or exterior walls of the Building, of the space
above and below the Demised Premises, of the parcel of land on which the Demised
Premises are located, and/or of any parking or other areas adjacent to the
Building except as follows:

     (i)   Tenant, at Tenant's sole cost and expense shall be permitted to
install a diesel fuel emergency stand-by generator UP TO 600 Kilowatts in size
and an enclosed diesel fuel storage tank not exceeding 6,000 gallons for
Tenant's exclusive use. Tenant shall be entitled to the use of the area
described on Exhibit A-2 attached hereto for the purpose of locating therein an
emergency stand-by generator and diesel fuel tank (with necessary conduit,
wiring or cabling) and other facilities consistent with Tenant's use of its
Demised Premises for continuous uninterrupted telecommunications services, all
at Tenant's sole cost and expense. Tenant shall have exclusive distribution
rights to said generator. In connection with the use of said generator Tenant
shall have the right to store gel cell batteries.

           Tenant shall have the right to conduct periodic tests of the
emergency stand-by generator after normal business hours at any time, provided
that Landlord is given reasonable notice, and that such tests will not interfere
with the operations of any other tenants, or the Building. Landlord shall work
with Tenant to establish a time mutually acceptable during non business hours to
accommodate Tenant's testing.

           Tenant shall install such emergency stand-by generator and related
items in accordance with all applicable municipal, State and Federal laws, rules
and regulations. Landlord shall have no responsibility or liability for the
installation, operation or maintenance of such emergency stand-by generator and
related items and Tenant shall employ required engineers on site to maintain and
service such emergency stand-by generator and related items. Tenant shall pay
directly to Landlord, as and for Additional Rent under the Lease, Sixty Thousand
Dollars ($60,000.00) per year for such stand-by emergency generator and related
items, payable $5,000.00 per month, commencing on the Commencement Date and
ending on the Lease Expiration Date.

                                      -6-
<PAGE>
 
     (ii)  Tenant shall have the use of up to Three Hundred (300) square feet of
roof space of the Building described in Exhibit A-3 attached hereto for the
purpose of the installation of a satellite dish/GPS receiver and air cooling
equipment at no additional charge. In the event Tenant requires roof space in
excess of Three Hundred (300) square feet for its satellite dish/GPS receiver
and air cooling equipment up to a maximum of Six Hundred (600) square feet,
Tenant shall pay directly to Landlord, as and for additional Rent under the
Lease, Two Hundred Fifty Dollars ($250.00) per square foot of additional roof
space yearly, payable in equal monthly installments commencing on the
Commencement Date and ending on the Lease Expiration Date.

     (iii) Tenant shall have the right to install, maintain and replace from
time to time a satellite dish/GPS receiver on the roof space of the Building as
set forth in Exhibit A-3 at Tenant's sole cost and expense and all of Tenant's
rights and duties set forth in Article 12 (relating to Tenant's duties and
obligations in making Tenant's changes) shall be applicable to and binding upon
Tenant with respect to such work, and Landlord shall furnish Tenant a right of
way between the rooftop and the Demised Premises for Tenant's wires on conduits
in connection therewith.

     (iv)  Landlord and Tenant agree that Tenant's communication, HVAC,
electrical and other various equipment will require Tenant to use Building
shafts, risers, chases, utility entrances, equipment rooms, and distribution
areas or conduits between the Demised Premises and other parts of the Building
(including the roof). Tenant shall be afforded the right to use where available,
and or construct conduits to connect Tenant's equipment.

     (v)   Tenant shall have the right to utilize and/or install four (4) four
inch (4") conduits from the telephone service point of entry to designated areas
within the Tenant's Demised Premises. Landlord will cooperate in locating points
of entry to provide redundancy of access for telecommunications services and
providers to the Building.

               ARTICLE 3 -- PREPARATION OF THE DEMISED PREMISES

     3.01  Tenant shall cause to be substantially performed all the work in the
Demised Premises as set forth in Exhibit C to be annexed hereto and made a part
hereof (the "Tenant's Work"), upon the terms and conditions specified therein.
Landlord shall provide a work allowance in the amount of $277,500.00 payable to
the contractor as part of the cost of the work. Tenant shall pay to the
contractor the balance of the cost of Work. Payments by each party shall be in
proportion to the total cost of the Work divided into each party's contribution,
payable to the Contractor against each invoice submitted for costs actually
incurred or materials actually delivered upon delivery to each party of evidence
of the Work completed.

     3.02  All of Tenant's duties and obligations set forth in Article 12
(relating to Tenant's duties and obligations in making Tenant's Changes) shall
be applicable to and binding upon Tenant with respect to any such work.

     3.03  Tenant's final plans, specifications and drawings covering all such
work are to be attached hereto as Exhibit C. Tenant shall not commence any work
referred to in Exhibit C until such plans, specifications, and drawings have
been received, receipted and approved by Landlord in accordance with the

                                      -7-
<PAGE>
 
provisions of Exhibit C. Landlord shall not unreasonably withhold or delay such
approval.

               ARTICLE 4 -- WHEN DEMISED PREMISES ARE READY FOR
                        OCCUPANCY AND COMMENCEMENT DATE

     4.01  The Commencement Date shall be March 1, 1999. Tenant shall not use or
occupy the Demised Premises for the permitted use until Tenant has received a
Certificate of Occupancy (temporary or final) issued by the appropriate
department of the municipality where the Building is located not inconsistent
with the Permitted Uses and with the restrictions set forth in Article 11
hereof.

     4.02  On the Commencement Date or at such time as Tenant shall take actual
possession of the whole or part of the Demised Premises, whichever shall be
earlier, it shall be conclusively presumed that the same were as of the
Commencement Date or the date or dates of such taking of possession, in the
condition in which Landlord was required to deliver the Demised Premises under
this Lease, unless within thirty (30) days after such date Tenant shall have
given Landlord notice specifying in which respects the Demised Premises were not
in satisfactory condition. However, nothing contained in this Section shall be
deemed to relieve Landlord from, and Landlord shall perform its obligations to
correct any latent defects and to complete, with reasonable speed and diligence,
such details of construction, mechanical adjustment and decoration, if any, as
Landlord shall be required to perform under this Lease and as shall have been
unperformed at the time Tenant took actual possession, but Tenant shall not be
entitled to any rent abatement on account of any such incomplete work.

     4.03  Upon the signing of this Lease by the parties, Tenant may enter the
Demised Premises to conduct Tenant's Work. Landlord shall have no liability or
obligation for the care or preservation of Tenant's property and Tenant shall
not interfere with Landlord or Landlord's contractors.

     4.04  Landlord agrees to provide access by the telephone company during the
course of construction to permit Tenant's installation of telephone lines,
cables, wires and equipment to service Tenant's office areas. Notwithstanding
the foregoing, the parties agree that the failure by the telephone company to
complete the telephone installation and to provide service on the date that the
Demised Premises are otherwise substantially complete (as hereinabove defined)
or occupied by Tenant, shall not delay or defer the determination of the
Commencement Date and the obligation to pay rent thereafter.

     4.05  When Tenant takes possession of the Demised Premises, it shall be
deemed to have accepted the Demised Premises as substantially completed as of
the date of such possession, subject to Landlord's obligations under Section
4.02 above.

                               ARTICLE 5 -- RENT

     5.01  Except as expressly provided herein, Tenant shall pay to Landlord
without notice or demand and without abatement, deduction or set-off, in lawful
money of the United States of America, at the office of the Landlord as set
forth in Article 1 hereof, or at such other place as Landlord may designate, the
Fixed Rent reserved under this Lease for each year of the Term, payable in equal
monthly installments in advance on the first day of each and every calendar
month during the Term; and additional rent consisting of 

                                      -8-
<PAGE>
 
all such other sums of money as shall become due from and payable by Tenant to
Landlord hereunder (for default in payment of which Landlord shall have the same
remedies as for a default in payment of Fixed Rent).

     5.02  Tenant shall pay the Fixed Rent and additional rent herein reserved
promptly as and when the same shall become due and payable under this Lease and
shall be liable to the Landlord for an administrative charge of 4% for rent paid
five (5) days subsequent to the date set in Article 5.01. If the Commencement
Date shall occur on a day other than the first day of a calendar month the Fixed
Rent, and additional rent shall be prorated for the period from the Commencement
Date to the last day of the said calendar month and shall be due and payable on
the Commencement Date. Notwithstanding the provisions of the next preceding
sentence, Tenant shall pay on account toward the first full calendar month
installment(s) of Fixed Rent, on the execution of this Lease, the Rent
Prepayment specified in Article 1 hereof.

     5.03  Whenever used in this Lease, the term (insofar as it pertains to this
Lease) "fixed rent", "minimum rent", "base rent", or "basic rent", or any such
term using the word "rental", "rents", or "rentals" in lieu of "rent", shall
mean Fixed Rent; and whenever used in this Lease, the term (insofar as it
pertains to this Lease) "rent", "rental", "Rent" or the plural of any of them,
shall mean Fixed Rent and additional rent.

                        ARTICLE 6 -- EXPENSE ESCALATION

     6.01  Tenant shall pay to Landlord, as additional rent, Expense Escalation
in accordance with this Article:

     A. Definitions: for the purpose of this Article, the following definitions
     shall apply:

     (i)   The term "Expense Base Factor" shall mean the Expenses as hereinafter
defined for the calendar year 1999.

     (ii)  The term "comparative year" shall mean the full calendar year in
which the term of this Lease commences, and each subsequent calendar year during
the Term of this Lease.

     (iii) The term "Expenses" shall mean the total of all the costs and
expenses incurred or borne by Landlord with respect to the operation and
maintenance of the Building and the services provided tenants therein including,
but not limited to, the costs and expenses incurred for and with respect to:
water rates and sewer rents; air-conditioning, ventilation and heating; any and
all electricity costs not paid directly to the Landlord by the tenants of the
Building (including Tenant); maintenance of the Building's exterior surfaces;
elevator cabs, lobby maintenance and cleaning; protection and security; lobby
decoration and interior and exterior landscape maintenance; repairs,
replacements and improvements which are appropriate for the continued operation
of the Building as a first-class office Building; maintenance; painting of non-
tenant areas; insurance; supplies; employee salaries and benefits;
administrative expenses; and the annual fee for management of the Building.

     Provided, however, that the foregoing costs and expenses shall exclude or
have deducted from them, as the case may be and as shall be appropriate:

     (a) leasing commissions and other leasing expenditures;

                                      -9-
<PAGE>
 
     (b) expenditures of capital improvements except those which under generally
accepted real estate practice are expensed or regarded as deferred expenses and
except for capital expenditures required by law, in either of which case the
cost thereof shall be included in Expenses for the comparative year in which the
costs are incurred and subsequent comparative years, on a straight line basis,
to the extent that such items are amortized over an appropriate period, but not
more than five years, with an interest factor equal to the prime rate of
Citibank at the time of Landlord's having incurred said expenditure.

     (c) amounts received by Landlord through proceeds of insurance to the
extent that the proceeds are compensation for expenses which would be or were
previously included in Expenses hereunder;

     (d) cost of repairs or replacements incurred by reason of fire or other
casualty or eminent domain;

     (e) advertising and promotional expenditures;

     (f) legal fees for disputes with tenants and legal and auditing fees, other
than legal and auditing fees reasonably incurred in connection with the
maintenance and operation of the Building or in connection with the preparation
of statements required pursuant to additional rent or lease escalation
provisions;

     (g) costs incurred in performing work or furnishing services for individual
tenants (including Tenant) at such tenant's expense to the extent that such work
or service is in excess of any work or service Landlord at its expense is
obligated to furnish to Tenant;

     (h) The cost of future renovations to the building, including without
limitation, the cost of any exterior renovations to the building;

     (i) "Takeover Expenses" (i.e., expenses incurred by Landlord with respect
to space located in another building of any kind or nature in connection with
the leasing of space in the Building);

     (j) Any amounts payable by Landlord by way of indemnity or for damages or
which constitute a fine, interest, or penalty, including interest or penalties
for any late payments of operating costs or pursuant to indemnities given by
Landlord to any Tenant pursuant to its Lease;

     (k) The operating costs incurred by Landlord relative to retail stores,
parking garage or any specialty service in the building;

     (l) The cost of correcting defects in construction or the removal or
encapsulation of asbestos containing materials;

     (m) The cost of overtime or other expense to Landlord in curing its
defaults;

     (n) The cost of any investigation, cleanup or remediation of any
environmental condition for which Lessee is not responsible under the Lease,
including costs of any penalties or fines in connection therewith;

     (o) The cost of any work or service performed for any tenant of space
(including Tenant) in the Building (i) at Landlord's cost and expense to the
extent that such work or service is in excess of any work or service which
Landlord is obligated to furnish hereunder to Tenant at Landlord's cost and
expense, or (ii) for which Landlord 

                                      -10-
<PAGE>
 
is reimbursed (other than through operation of this Article or similar
provisions in other leases of space in the Building);

     (p) The cost of any judgment, settlement, or arbitration award resulting
from any liability of Landlord (other than a liability for amounts otherwise
includable in Expenses hereunder) and all expenses incurred in connection
therewith;

     (q) Costs relating to withdrawal liability or unfunded pension liability
under the Multi-Employer Pension Plan Act or similar law;

     (r) Any interest, fine, penalty or other late charges payable by Landlord
(not due to Tenant's default);

     (s) Costs incurred by Landlord which result from Landlord's or other
Building tenants' breach of a lease or Landlord's tortious or negligent conduct;
and

     (t) Costs incurred by Landlord to assure building Systems are Year 2000
compatible.

     Without limiting the generality of the foregoing, capital expenditures
incurred by Landlord to comply with existing or future federal, state or local
laws, rules or regulations of governmental authorities having jurisdiction over
the Building, including without limitations, the American with Disabilities Act,
as now in effect.

     If Landlord shall purchase any item of capital equipment or make any
capital expenditure designed to result in savings or reductions in Expenses,
then the costs for same shall be included in Expenses. The costs of capital
equipment or capital expenditures are so to be included in Expenses for the
comparative year in which the costs are incurred and subsequent comparative
years, on a straight line basis, to the extent that such items are amortized
over such period of time as reasonably can be estimated as the time in which
such savings or reductions in Expenses are expected to equal Landlord's costs
for such capital equipment or capital expenditure, with an interest factor equal
to the prime rate of Citibank at the time of Landlord's having incurred said
costs. If Landlord shall lease any such item of capital equipment designed to
result in savings or reductions in Expenses, then the rentals and other costs
paid pursuant to such leasing shall be included in Expenses for the comparative
year in which they were incurred.

     6.02  Commencing with the second comparative year, if the Expenses
estimated in the manner provided in Article 6.03 for a comparative year shall be
greater than Expense Base Factor, Tenant shall pay to Landlord, additional rent
for such comparative year, in the manner hereinafter provided, an amount equal
to The Tenant's Share of the excess of the Expenses for such comparative year
over the Expense Base Factor (such amount being hereafter called the "Expense
Payment").

     6.03  Commencing with the second comparative year, and each year thereafter
for the balance of the Lease term, thirty (30) days prior to the commencement of
each comparative year, Landlord will submit to Tenant Landlord's Certified
Public Accountant's estimate of projected expenses for such year as provided in
Article 6.04. The estimate shall also set forth the total projected expenses, if
any, due to Landlord from Tenant for such year pursuant to Article 6.02. The
rendition of such estimate shall constitute prima facie proof of the accuracy
thereof. If such statement shows an Expense Payment due to Landlord with respect
to the forthcoming comparative

                                      -11-
<PAGE>
 
year, one-twelfth of this amount shall be payable monthly as additional rent,
commencing with the first month of such comparative year.

     No later than sixty (60) days after the conclusion of each comparative year
Landlord shall deliver to Tenant a final statement from its Certified Public
Accountant as provided in Article 6.04 setting forth the actual Expenses for the
preceding year. Within thirty (30) days of Tenant's receipt of such statement
Landlord and Tenant will make an appropriate cash adjustment for any
underestimate or overestimate of Landlord's Expenses for the preceding
comparative year (which underestimate shall result in additional rent payable as
herein provided).

     6.04  The estimated and final statements of Expenses to be furnished by
Landlord as provided above shall be certified by Landlord, and shall be prepared
in reasonable detail for the Landlord by a Certified Public Accountant (who may
be the Certified Public Accountant now or then employed by Landlord for the
audit of its accounts); said Certified Public Accountant may rely on Landlord's
allocations and estimates wherever operating cost allocations or estimates are
needed for this Article. The statements thus furnished to Tenant shall
constitute a final determination as between Landlord and Tenant of the Expenses
for the period represented thereby, unless Tenant within ninety (90) days after
they are furnished shall give a notice to Landlord that it disputes their
accuracy or their appropriateness, which notice shall specify the particular
respects in which the statement is accurate. Pending the resolution of such
dispute, Tenant as herein provided shall pay the additional rent to Landlord in
accordance with the statements furnished by Landlord. After payment of said
additional rent, Tenant shall have the right, during reasonable business hours
and upon not less than five (5) business days' prior written notice to Landlord,
to have Tenant's Certified Public Accountant or other authorized agent or
representative examine Landlord's books and records with respect to the
foregoing, provided such examination is commenced within thirty (30) days and
concluded within sixty (60) days following the rendition of the statement in
question.

     6.05  In any such dispute as to said statement Landlord and Tenant or their
respective Certified Public Accountants shall select a national "Big Six"
accounting firm whose determination shall be conclusive in the resolution of the
dispute. In the event the Big Six accounting firm's determination results in a
finding that the amount of Expenses due is within five (5%) percent of the
amount claimed by Landlord, Tenant shall pay the cost of said Big Six accounting
firm. If the amount due is determined to be more than five (5%) percent less
than the amount claimed by Landlord, Landlord shall pay the cost of said Big Six
accounting firm.

     6.06  Real Estate Tax Increase Payment.

     (1)  For each Tax Year (hereinafter defined) after the tax year ending
December 31, 1999 during the Term, Tenant shall pay, as additional rent, the Tax
Payment (hereinafter defined) for such Tax Year.

     (2)  Tax Definitions:

     (a)  The term "Real Estate Taxes" shall mean the sum of the real estate
taxes and assessments and special assessments imposed upon the Building and the
plot of land on which the Building stands (the "Land") and any rights or
interests appurtenant thereto payable by Landlord during any Tax Year or any
service charges or

                                      -12-
<PAGE>
 
other payments in lieu of taxes imposed by any tax abatement granted the
Landlord and payable by the Landlord. If at any time during the Term the methods
of taxation prevailing at the time of the commencement thereof shall be altered
so that in lieu of or as an addition to or as a substitute for the whole or any
part of the taxes, assessments, levies, impositions or charges now levied,
assessed or imposed, there shall be levied, assessed or imposed a tax,
assessment, levy, imposition or charge wholly or partially as a capital levy or
on the rents, licenses or other charges received with respect to the Term, the
Land or the Building, then all such taxes, assessments, levies, impositions or
charges payable shall be deemed to be included within the term "Real Estate
Taxes" for the purposes hereof. Except as provided above, Real Estate Taxes
shall not include franchise, income or similar taxes of Landlord. A copy of the
tax bill of The City of Jersey City or other taxing authority imposing Real
Estate Taxes on the Land or the Building shall be sufficient evidence of the
amount of Real Estate Taxes. Notwithstanding the fact that the aforesaid
additional rent is measured by Real Estate Taxes, such amount is additional rent
and shall be paid by Tenant as provided herein regardless of the fact that
Tenant may be exempt, in whole or in part, from the payment of any Real Estate
Taxes by reason of Tenant's diplomatic status or for any other reason
whatsoever.

     (b)  The term "Base Tax Year" shall mean the tax year ending December 31,
1999.

     (c)  The term "Tax Year" shall mean each real estate fiscal tax year of the
City of Jersey City, New Jersey, following the Base Tax Year, any portion of
which occurs during the Term.

     (d)  The term "Tax Payment" shall mean Tenant's Share for the Demised
Premises of the amount by which the Real Estate Taxes payable for a Tax Year
exceed the Real Estate Taxes payable for the Base Tax Year, whether such
increase results from a higher tax rate or an increase in the assessed valuation
of the Land or the Building, or both or from any other cause or reason
whatsoever. Notwithstanding the foregoing, if there is an increase in assessed
valuation of the Building resulting from an addition or improvement to the
Building by another tenant, then any increase in Real Estate Taxes attributable
to such increase shall not be included in the computation of Tax Payment
hereunder.

     (3)  With respect to each Tax Year occurring in whole or in part during the
term of the Term, Tenant shall pay to Landlord the Tax Payment, in equal monthly
installments during the calendar year in which such Tax Year commences in the
manner hereinafter described. At any time during the calendar year in which a
Tax Year commences, Landlord may furnish to Tenant a written estimate (a "Tax
Estimate") of the Tax Payment for such Tax Year ("Estimated Tax Payment"). Such
estimate shall be determined by Landlord by applying to the most recently
announced assessed value of the Land and Building (whether final or otherwise)
such tax rate as Landlord shall anticipate is the tax rate to be finally
determined for such Tax Year, but such rate shall in no event exceed by more
than ten (10%) percent the then current tax rate. Subject to adjustment as
hereinafter provided, Tenant shall pay to Landlord on the first day of each
calendar month during such calendar year, an amount equal to one-twelfth (1/12)
of the Estimated Tax Payment for the Tax Year commencing during such calendar
year. If Landlord furnishes a Tax Estimate for a Tax Year subsequent to the
commencement of the calendar year in which such Tax Year begins, then

     (a)  until the first day of the month following the month in which the Tax
Estimate is furnished to Tenant, Tenant shall 

                                      -13-
<PAGE>
 
continue to pay to Landlord on the first day of each month an amount equal to
the monthly sum payable by Tenant to Landlord with respect to the next previous
Tax Year.

     (b)   promptly after the Tax Estimate is furnished to Tenant, Landlord
shall give notice to Tenant stating whether the amount previously paid by Tenant
to Landlord during such calendar year was greater or less than the installments
of the Estimated Tax Payment to be paid during such calendar year in accordance
with the Tax Estimate, and

     (i)   if there shall be a deficiency, Tenant shall pay the amount thereof
within thirty (30) days after demand therefor, or

     (ii)  if there shall have been an overpayment, Landlord shall credit the
amount thereof against the next monthly installments of the Fixed Annual Rent
payable under this Lease, and

     (c)   on the first day of the month following the furnishing of Tenant of
the Tax Estimate, and monthly thereafter until the rendering to Tenant of a Tax
Statement (hereinafter defined) for such Tax Year, Tenant shall pay to Landlord
an amount equal to one twelfth (1/12) of the amount shown on such Tax Estimate.
Promptly after the amount of Real Estate Taxes is established for a Tax Year,

     (i)   Landlord shall furnish to Tenant a written statement (a "Tax
Statement") setting forth the Tax Payment for such Tax Year, and stating whether
the sum of the installments previously paid by Tenant to Landlord pursuant to
the Tax Estimate or otherwise for such Tax Year was greater or less than the sum
of the installments of the Tax Payment to be paid for such Tax Year in
accordance with the Tax Statement,

     (ii)  any deficiency or overpayment shall be disposed of in the manner of a
deficiency or overpayment in Estimated Tax Payment, and

     (iii) on the first day of the month following the month in which the Tax
Statement is furnished to the Tenant, and monthly thereafter until a new Tax
Estimate or Tax Statement is furnished to Tenant, Tenant shall pay to Landlord
an amount equal to one-twelfth (1/12) of the Tax Payment shown on the Tax
Statement.

     (4)   The Tax Estimates and Tax Statements to be furnished by Landlord as
provided above shall be certified by Landlord and a statement thus furnished to
Tenant shall constitute a final determination as between Landlord and Tenant of
the Estimated Tax Payment or Tax Payment, as the case may be, for the period
represented thereby, unless Tenant within sixty (60) days after the statement is
furnished shall give a notice to Landlord that Tenant disputes the
reasonableness, accuracy or appropriateness of such statement, which notice
shall specify the particular respects in which the statement is unreasonable,
inaccurate or inappropriate. Pending the resolution of such dispute, Tenant as
herein provided shall make the Estimated Tax Payment or Tax Payment, as the case
may be, to Landlord without prejudice to Tenant's position. In any such dispute
as to a Tax Estimate or Tax Statement, Landlord and Tenant shall, within ten
(10) days after the giving of Tenant's notice disputing the reasonableness,
accuracy or appropriateness of such statement, select a national "Big Six"
accounting firm whose determination shall be conclusive in the resolution of the
dispute. If the dispute shall be determined in Tenant's favor, Landlord shall
forthwith pay to Tenant the amount of Tenant's overpayment resulting from
compliance with Landlord's statement and shall pay for the cost of the
accounting firm. In the event overpayment is greater than five (5%) percent,
Landlord shall pay interest to

                                      -14-
<PAGE>
 
Tenant on such overpayment at the rate of 2% in excess of the prime interest
rate as set forth from time to time by Citibank, N.A. from the date of payment
of such amounts by Tenant until repayment of such overpayment by Landlord. If
the dispute shall be determined in Landlord's favor, Tenant shall pay for the
costs of the accounting firm.

     (5)   Only Landlord shall be eligible to institute tax reduction or other
proceedings to reduce the assessed valuation of the Land or the Building. Should
Landlord be successful in any such reduction proceedings and obtain a rebate for
any Tax Year for which Tenant has paid installments of the Tax Payment,
Landlord, after deducting the expenses incurred in obtaining such rebate
including, without limitation, attorneys' fees, court, or other administrative
costs and disbursements, shall credit Tenant's Share of such rebate against the
next monthly installment of the Fixed Annual Rent payable under this Lease or in
the case of the last month of the Term, pay such amount to Tenant. In the event
that the assessed valuation which had been utilized in computing the Real Estate
Taxes payable for the Base Tax Year is reduced (as a result of settlement, final
determination of legal proceedings or otherwise) then

     (i)   the Real Estate Taxes for the Base Tax Year shall be retroactively
adjusted to reflect such reduction;

     (ii)  the monthly installments of Additional Rent shall be adjusted
accordingly; and

     (iii) all retroactive Additional Rent resulting from such adjustment shall
be payable by Tenant within thirty (30) days after the rendition of a bill
therefor.

     6.07  In no event shall the Fixed Rent due under this Lease be reduced by
virtue of this Article.

     6.08  If the Commencement Date of the term of this Lease is not the first
day of the first comparative year, then the additional rent due hereunder for
such first comparative year shall be a proportionate share of said additional
rent for the entire comparative year, said proportionate share to be based upon
the length of time that the Lease term shall have been in existence during such
first comparative year. Upon the date of any expiration or termination of this
Lease (except termination because of Tenant's default) whether the same be the
date hereinabove set forth for the expiration of the Term or any prior or
subsequent date, a proportionate share of said additional rent for the
comparative year during which such expiration or termination occurs shall
immediately become due and payable by Tenant to Landlord, if it was not
theretofore already billed and paid. The said proportionate share shall be based
upon the length of time that this Lease shall have been in existence during such
comparative year.

     6.09  Subject to the provisions of Section 6.10 below, Landlord's and
Tenant's obligation to make the adjustments referred to in this Article shall
survive any expiration or termination of this Lease.

     6.10  Any delay or failure of Landlord in billing any expense escalation
hereinabove provided shall not constitute a waiver of or in any way impair the
continuing obligation of Tenant to pay such expense escalation hereunder
provided however, if Landlord fails to bill Tenant within twenty-four (24)
months after the end of a tax or expense year, right to bill for such year shall
be waived.

                                      -15-
<PAGE>
 
                        ARTICLE 7 -- ELECTRICAL ENERGY

     7.01  Electrical energy consumed by Tenant in the Demised Premises through
wall and floor outlets, for lighting and business equipment and the Tenant's
auxiliary HVAC system shall be separately metered and purchased by Tenant from
the utility supplying electricity to the Building. Tenant shall install as part
of Tenant's Work the electrical meter(s) for the Demised Premises. Landlord
shall install at its own cost the risers, conduits, feeders and wiring
installations in the Building and to the Demised Premises sufficient to provide
the Demised Premises with electrical energy, in a safe and suitable manner,
equal to 200 amps at 480 volts, which is approximately one hundred fifty (150)
Kilowatts. Electricity for heating, ventilating and air conditioning including
for any fan used in connection therewith during Regular Business Hours shall not
be included on such meter and shall be paid for by the Landlord. Tenant shall
pay to Landlord, as additional rent, the cost of electricity for heating,
ventilating and air conditioning including for any fan used in connection
therewith, in the Demised Premises during other than Regular Business Hours
pursuant to Article 8.01.

     7.02  Tenant, at Tenant's sole cost and expense and subject to all of
Tenant's duties and obligations set forth in Article 12 (relating to Tenant's
duties and obligations in making Tenant's changes), shall be afforded access to
the Building's electrical supply located in the basement of the Building. Tenant
may connect existing power in the basement of the Building to Tenant's dedicated
electrical feed and conduit to be installed at Tenant's sole cost and expense,
to obtain a minimum of five hundred (500) Kilowatts of power to the Demised
Premises. Landlord represents and warrants that the Building has sufficient
capacity to provide five hundred (500) Kilowatts of power during the Term of the
Lease.

     7.03  Tenant shall have the right at any time during the Term of the Lease,
to upgrade the Building's electrical service at Tenant's sole cost and expense
and subject to all of Tenant's duties and obligations set forth in Article 12
(relating to Tenant's duties and obligations in making Tenant's changes).

     7.04  Landlord's and Tenant's obligations to make the adjustments and
payments referred to in this Article shall survive any expiration or termination
of this Lease.

     7.05  Subject to Section 7.01 above, Tenant covenants and agrees that at
all times its use of electrical current shall not exceed the capacity of
existing feeders to the Building or the risers, conduits, or wiring installation
in the Building, and Tenant shall not use any electrical equipment which, in
Landlord's opinion reasonably exercised, will overload such installations or
interfere with the use thereof by other tenants of the Building.

     7.06  Tenant may purchase from Landlord, at Landlord's option, all
replacements of electric fluorescent tubing and shall pay Landlord for
installing same.

                 ARTICLE 8 -- VENTILATION AND AIR CONDITIONING

     8.01  There shall be installed in the Demised Premises, as part of the work
provided for in Section 3.01, the Building heating, ventilating and air-
conditioning systems described and designed to substantially meet the following
performance specifications:

                                      -16-
<PAGE>
 
                               Inside Condition
                               ----------------
                       Cooling Season 75 degrees F.D.B.
                          Heating Season 68 degrees F

                               Outside Condition
                               -----------------
                Cooling Season 91 degrees F.D.B./76 degrees FWB
                         Heating Season 10 degrees F.

     Landlord shall be under no liability to Tenant if such performance
specifications should not be able to be met prior to the said systems being
balanced. Landlord, at its expense, shall maintain and operate such systems and
shall furnish heat, ventilation and air-conditioning in the Demised Premises
through such systems, subject to Article 9.07, in compliance with such
performance specifications, during Regular Business Hours. If Tenant shall
require ventilating and air-conditioning service or heating service at any other
time other than Regular Business Hours (hereinafter called "after hours"),
Landlord shall furnish after hours ventilating and air-conditioning service or
heating service upon reasonable advance notice from Tenant, and Tenant shall pay
Landlord therefore, as additional rent upon rendition of a bill, the A.C. charge
and the H. charge. The A.C. charge and the H. charge shall be subject to
adjustment upward from time to time, to reflect the actual increase in
Landlord's reasonable out of pocket costs in providing services to extent not
included in expenses.

     8.02  Landlord will not be responsible for the failure of the air-
conditioning system to meet the performance specifications set forth above if
such failure results from the occupancy of the Demised Premises with more than
an average of one person for each 150 square feet of Tenant's Floor Space or if
Tenant installs and operates machines and appliances, the installed electrical
load of which when combined with the load of all lighting fixtures exceeds 3.5
watts per square foot of Tenant's Floor Space in any one room or other area. If
due to use of the Demised Premises in a manner exceeding the aforementioned
occupancy and electrical load criteria, or due to rearrangement of partitioning
after the initial preparation of the Demised Premises, interference with normal
operation of the air-conditioning in the Demised Premises results, necessitating
changes in the air-conditioning system servicing the Demised Premises, such
changes shall be made by Landlord upon written notice to Tenant at Tenant's sole
cost and expense. Tenant agrees to lower and close window coverings when
necessary because of the sun's position whenever the said air conditioning
system is in operation, and Tenant agrees at all times to cooperate fully with
Landlord and to abide by all the regulations and requirements which Landlord may
prescribe for the proper functioning and protection of the said air-conditioning
system. Landlord throughout the Term, shall have free and unrestricted access to
any and all air-conditioning facilities in the Demised Premises. Any such access
must be on prior reasonable notice to Tenant, except in emergency with a
representative of Tenant present and exercised so as not to interfere with
Tenant.

     8.03  Any damage caused to heating, air-conditioning, and ventilating
equipment, appliances or appurtenances thereto as a result of the negligence of,
or careless operation of, the same by Tenant or its agents, servants, employees,
licensees, invitees, or visitors, shall be repaired by Landlord, and the actual
reasonable out-of-pocket cost and expenses thereof shall be paid by Tenant as
additional rent, within thirty (30) days after being billed therefor.

                                      -17-
<PAGE>
 
                    ARTICLE 9 -- LANDLORD'S OTHER SERVICES

     9.01  Landlord shall provide public elevator service to the floor(s) on
which the Demised Premises are situated during Regular Business Hours, and shall
have at least one elevator subject to call at all other times. The elevator(s),
or any or all of them, if more than one, may be operated by automatic control
and/or by manual control, as Landlord shall determine at any time or from time
to time. Landlord shall not be obligated to furnish an operator for any
automatic elevator and shall have no liability to Tenant for discontinuing the
service of any operator theretofore furnished. If Tenant shall require after
hours service of elevator(s) or of the loading area in the Building under such
circumstances as, in Landlord's reasonable judgment, will require service or
attention by Landlord's personnel, Tenant shall pay Landlord, on demand, a
reasonable charge attributable to such service or attention.

     9.02  Provided that Tenant shall keep the Demised Premises in good order,
Landlord shall cause the Demised Premises, including the exterior and the
interior of the windows thereof (subject to Tenant maintaining unrestricted
access to such windows), to be cleaned in accordance with the standards set
forth in Exhibit D annexed hereto and made a part hereof. Tenant will not clean,
nor require, permit or allow any window in the premises to be cleaned from the
outside. Tenant shall pay to Landlord within thirty (30) days of notice the
costs incurred by Landlord for (a) cleaning work in the Demised Premises or the
Building required because of (i) misuse or neglect on the part of Tenant or its
employees or visitors, (ii) use of portions of the Demised Premises for
preparation, serving, or consumption of food or beverages, reproducing
operations, private lavatories or toilets or other special purposes requiring
greater or more difficult cleaning work than office area, (iii) interior glass
surfaces, (iv) non-Building standard materials or finishes installed by Tenant
or at its request, (v) increases in frequency or scope in any of the items set
forth in Exhibit D as shall have been requested by Tenant, and (b) removal from
the Demised Premises and the Building of (i) so much of any refuse and rubbish
of Tenant as shall exceed that properly accumulated daily in the routine or
ordinary business office and (ii) all of the refuse and rubbish of Tenant's
machines and the refuse and rubbish of any other eating facilities requiring
special handling (known as "wet garbage"). Landlord and its cleaning contractor
and their employees shall have after hours access to the Demised Premises and
the use of the Tenant's light, power and water in the Demised Premises as may be
reasonably required for the purpose of cleaning the Demised Premises.
Extraordinary waste (such as crates, cartons, boxes, etc. and used furniture or
equipment) shall be removed from the Building by Tenant at Tenant's own cost and
expense. At no time shall Tenant place any waste of any kind in any public
areas. If Tenant does so, the parties agree that everything so placed shall be
deemed abandoned and of no value to Tenant and Landlord may have the same
removed and disposed of at Tenant's expense. Such expenses shall be deemed
additional rent payable by Tenant within thirty (30) days after being billed
therefor together with reasonable back-up with respect to such expenses. This
remedy is in addition to any other remedies Landlord may have under this lease.

     9.03  Tenant reserves the right to obtain its own janitorial services from
a third party for the Demised Premises upon written notice to Landlord ("Third
Party Cleaning Service"). Landlord shall have the right to approve the party
providing the Third Party Cleaning Service in its reasonable discretion. In the
event that Tenant utilizes the Third Party Cleaning Service, janitorial 

                                      -18-
<PAGE>
 
service to any portion of the Building, except for common areas, shall not be
excluded from Expenses.

     9.04  Landlord, at its expense, shall furnish adequate hot and cold water
at ordinary lavatory temperature to each floor of the Building for drinking,
lavatory, and cleaning purposes, together with soap, towels and toilet tissue
for each lavatory. If Tenant uses water for any other purpose Landlord, at
Tenant's expense, may install meters to measure Tenant's consumption of cold
water and/or hot water for such other purposes and/or steam, as the case may be.
Tenant shall pay for the quantities of cold water and hot water shown on such
bills therefor. In connection with permitted kitchen use, the amount of hot
water demand shall not exceed the excess Building design capacity.

     9.05  Landlord, at its own expense, and at Tenant's request, shall insert
initial listings on the Building Directory of the names of Tenant, and any
affiliate, and the names of any of their officers and employees, provided that
the names so listed shall not take up more than Tenant's proportionate share of
the space on the Building Directory. All Building Directory changes made at
Tenant's request after the Tenant's initial listings have been placed on the
Building Directory shall be made by Landlord at the expense of Tenant, and
Tenant agrees to promptly pay to Landlord as additional rent the cost of such
changes within thirty (30) days after Landlord has submitted an invoice
therefor.

     9.06  With respect to parking of vehicles (if parking is provided under
Article 1 hereof):

     A.  Landlord represents that throughout the Term there will be a paved,
illuminated parking area for the Building with the number of Parking Spaces
specified in Article 1. If Landlord so elects, Tenant shall require its
personnel and visitors to park their vehicles only in Parking Spaces designated
by Landlord for Tenant's use for its personnel and visitors on a "first come,
first served" basis. Landlord reserves the right at all times to redesignate
such Parking spaces. Tenant, its personnel and visitors shall not at any time
park any trucks or delivery vehicles in any of the parking areas, except for the
loading dock area for deliveries.

     B.  All Parking Spaces and any other parking areas used by Tenant, its
personnel and visitors will be at their own risk, and Landlord shall not be
liable for any injury to person or property, or for loss or damage to any
automobile or its contents, resulting from theft, collision, vandalism or any
other cause whatsoever.

     C.  Tenant shall agree to all requests by Landlord that Tenant and its
employees and visitors remove their vehicles from the Parking Spaces to another
parking area provided by Landlord at reasonable periods for purposes of cleaning
and maintenance of such spaces or as required for purposes of snow removal,
provided that Landlord will perform such cleaning, maintenance and snow removal
and make such Parking Spaces available to Tenant and its employees and visitors
as promptly as possible.

     9.07  Landlord shall keep and maintain the public areas and the public
facilities of the Building and the grounds clean and in good order, and the
sidewalks and parking areas adjoining the Building shall be kept free of
accumulation of snow and ice (except any overnight parking area) or unlawful
obstruction.

     9.08  Landlord reserves the right, without any liability to Tenant, except
as otherwise expressly provided in this Lease, and without being in breach of
any covenant of this Lease, to stop,

                                      -19-
<PAGE>
 
interrupt or suspend service of any of the heating, ventilating, air
conditioning, electric, sanitary, elevator or other Building systems serving the
Demised Premises, or the rendition of any other services required of Landlord
under this Lease, whenever and for so long as may be necessary, by reason of
accidents, emergencies, the making of repairs or changes which Landlord is
required by this Lease or by law to make or in good faith deems advisable, or by
reason of unavoidable delays. In each instance Landlord shall exercise
reasonable diligence to eliminate the cause of stoppage and to effect
restoration of service and shall give Tenant reasonable prior notice, when
practicable, of the commencement and anticipated duration of such stoppage, and
if any work is required to be performed in or about the Demised Premises for
such purpose, the provision of Section 14.03 shall apply. Tenant shall not be
entitled to any diminution or abatement of rent or other compensation nor shall
this Lease or any of the obligations of Tenant be affected or reduced by reason
of the interruption, stoppage or suspension of any of the Building systems or
services arising out of the causes set forth in this Section.

                               ARTICLE 10 -- USE

     10.01  The "Permitted Use" of the Demised Premises for the purposes
specified in Article 1 hereof shall not in any event be deemed to include, and
Tenant shall not use, or permit the use of, the Demised Premises or any part
thereof for:

     (a) sale of, or traffic in, any spirituous liquors, wines, ale or beer kept
in the Demised Premises;

     (b) sale at retail of any other products or materials kept in the Demised
Premises, by vending machines or otherwise, or demonstrations to the public,
except as may be specifically agreed to by Landlord in writing;

     (c) manufacturing, printing, except for the operation of normal business
office reproducing and printing equipment and business machines incidental to
the conduct of Tenant's business and for Tenant's own requirements at the
Demised Premises, provided that such use shall not exceed that portion of the
mechanical or electrical capabilities of the Building equipment allocable to the
Demised Premises;

     (d) the rendition of medical, dental or other diagnostic or therapeutic
services;

     (e) the conduct of a public auction of any kind;

     (f) the conduct of a banking, trust company, savings bank, safe deposit,
savings and loan association or loan company business;

     (g) the issuance and sale of traveler's checks, foreign drafts, letters of
credit, foreign exchange or domestic money orders (except as incidentally
required in conduct of Tenant's normal business activity);

     (h) the receipt of money for transmission (except as is incidentally
required in conduct of Tenant's normal business activity); or

     (i) a restaurant, bar, or the sale of confectionery, tobacco, newspapers,
magazines, soda, beverages, sandwiches, ice cream, baked goods or similar items,
or the preparation, dispensing or consumption of food and beverages in any
manner whatsoever.

                                      -20-
<PAGE>
 
    10.02  Tenant shall not suffer or permit the Demised Premises or any part
thereof to be used in any manner, or anything to be done therein, or suffer or
permit anything to be brought into or kept therein, which would in any way (i)
violate any of the provisions of any grant, lease or mortgage to which this
Lease is subordinate, (ii) violate any laws or requirements of public
authorities, (iii) make void or voidable any fire or liability insurance policy
then in force with respect to the Building, (iv) make unobtainable from
reputable insurance companies authorized to do business in New Jersey at
standard rates any fire insurance with extended coverage, or liability, elevator
or boiler or other insurance required to be furnished by Landlord under the
terms of any lease or mortgage to which this Lease is subordinate, (v) cause or
in Landlord's opinion be likely to cause physical damage to the Building or any
part thereof, (vi) constitute a public or private nuisance, (vii) impair, in the
reasonable opinion of the Landlord, the appearance, character or reputation of
the Building, (viii) discharge objectionable fumes, vapors or odors into the
Building air conditioning system or into Building flues or vents not designed to
receive them or otherwise in such manner as may unreasonably offend other
occupants, (ix) impair or interfere with any of the Building services or the
proper and economic heating, cleaning, air conditioning or other servicing of
the Building or the Demised Premises or impair or interfere with or tend to
impair or interfere with the use of any of the other areas of the Building by,
or occasion annoyance or inconvenience to, Landlord or any of the other tenants
or occupants of the Building, or (x) cause Tenant to default in any of its other
obligations under this Lease.  The provisions of this Section, and the
application thereof, shall not be deemed to be limited in any way to or by the
provisions of any of the following Sections of this Article or any of the Rules
and Regulations referred to in Article 20 or Exhibit B attached hereto, except
as may therein be expressly otherwise provided.

    10.03  If any governmental license or permit, other than a Certificate of
Occupancy for the Building, shall be required for the proper and lawful conduct
of Tenant's business in the Demised Premises, or any part thereof, and if
failure to secure such license or permit would in any way affect Landlord, then
Tenant, at its expense, shall duly procure and thereafter maintain such license
or permit, but in no event shall failure to procure and maintain same by Tenant
affect Tenant's obligations hereunder.  Tenant shall not at any time use or
occupy, or suffer or permit anyone to use or occupy the Demised Premises, or do
or permit anything to be done in the Demised Premises, in violation of the
Certificate of Occupancy for the Demised Premises or for the Building.

    10.04  Except as provided in Exhibit C, Tenant shall not place a load upon
any floor of the Demised Premises exceeding the floor load per square foot which
such floor was designed to carry and which is allowed by certificate, rule,
regulation, permit or law, except that to the extent Tenant's floor loading
requirements shall, at any time, exceed the floor load per square foot, Tenant,
at Tenant's expense may reinforce the floor as required to accommodate Tenant's
requirements.  Landlord reserves the right to prescribe the weight and position
of all safes and vaults which must be placed by Tenant, at Tenant's expense.
Business machines and mechanical equipment shall be positioned and maintained by
Tenant, at Tenant's expense, in such manner as shall be sufficient in Landlord's
judgment to absorb and prevent vibration, noise and annoyance.

                                      -21-
<PAGE>
 
                       ARTICLE 11 -- ACCESS, CHANGES IN
                           BUILDING FACILITIES, NAME

    11.01  All walls, windows and doors bounding the Demised Premises (including
exterior Building walls, core corridor walls and doors and any core corridor
entrance), except the inside surfaces thereof, any terraces or roofs adjacent to
the Demised Premises, and space in or adjacent to the Demised Premises used for
shafts, stacks, pipes, conduits, fan rooms, ducts, electric or other utilities,
sinks or other Building facilities, and the use thereof, as well as access
thereto through the Demised Premises for the purposes of operating, maintenance,
decoration and repair, are reserved to Landlord, subject to Tenant's rights
under Article 2 above.

    11.02  Tenant shall permit Landlord to install, use and maintain pipes,
ducts and conduits within or through the Demised Premises, or through the walls,
columns and ceiling therein, provided that the installation work is performed at
such times and by such methods as will not unreasonably interfere with Tenant's
use and occupancy of the Demised Premises, or damage the appearance thereof, or
materially affect Tenant's layout.  Where access doors are required for
mechanical trades in or adjacent to the Demised Premises, Landlord shall furnish
and install such access doors at its expense, and confine their location
wherever practical to closets, coat rooms, toilet rooms, corridors, and kitchen
or pantry rooms.  Landlord and Tenant shall cooperate with each other in the
location of Landlord's and Tenant's facilities requiring such access doors.

    11.03  Landlord or Landlord's agents or employees shall have the right upon
request made on reasonable advance notice to Tenant, accompanied by an
authorized employee of Tenant at the Demised Premises, to enter and/or pass
through the Demised Premises or any part thereof, at reasonable times during
reasonable hours, (i) to examine the Demised Premises or to show them to lessors
of superior leases, holders of mortgages, insurance carriers, or prospective
purchasers, mortgagees or lessees of the land or the Building, or prospective
tenants, and (ii) for the purpose of making such repairs or changes in or to the
Demised Premises or in or to the Building or its facilities as may be provided
for by this Lease or as Landlord may deem necessary or as Landlord may be
required to make by law or in order to repair and maintain the Building or its
fixtures or facilities.  Landlord shall be allowed to take into and temporarily
store upon the Demised Premises all materials which may be reasonably required
for such repairs, changes or maintenance.  However, Landlord's rights under this
Section shall be exercised in such manner as will not unreasonably interfere
with Tenant's use and occupancy of the Demised Premises.  Landlord, its agents
or employees, shall also have the right to enter on and/or pass through the
Demised Premises, or any part thereof without notice at such times as such entry
shall be required by circumstances of emergency affecting the Demised Premises
or the Building.

    11.04  Landlord reserves the right, at any time after completion of the
Building, without incurring any liability to Tenant therefor, to make such
changes in or to the Building and the fixtures and equipment thereof, as well as
in or to the street entrances, halls passages, elevators and stairways thereof,
as it may deem necessary or desirable; provided that there be no unreasonably
lengthy interference with the use of the Demised Premises or in the services
furnished to the Demised Premises.

    11.05  Landlord may limit and restrict, as provided in the Rules and
Regulations attached hereto as Exhibit B, the means of

                                      -22-
<PAGE>
 
access to the Demised Premises outside of Regular Business Hours, so long as
Tenant's employees and authorized agents have reasonable access to all parts of
the Demised Premises. Tenant, and its agents, employees and visitors shall be
entitled to access from the Demised Premises to, and the right to use, the
toilets, lavatories and powder rooms only on the floor (or floors) on which the
Demised Premises are located.   24 hours, 7 days per week.

    11.06  Landlord reserves the right to select a name for the Building and to
make such change or changes of name as it may deem appropriate during Tenant's
occupancy, and Tenant agrees not to refer to the Building by any other name than
(i) the name as selected by Landlord, or (ii) the postal address approved by the
U.S. Post Office.


                        ARTICLE 12 -- TENANT'S CHANGES

    12.01  Tenant may, at any time and from time to time during the Term, at its
sole expense, make such other alterations, additions, installations,
substitutions, improvements and decorations (hereinafter collectively called
"Changes" and, as applied to changes provided for in this Article, "Tenant's
Changes") to the Demised Premises, including structural upgrades and/or
improvements to the Demised Premises or structural components of the Building to
the extent they are necessary for Tenant to conduct its telecommunications
business including the construction of walls or other such interior coverings
over some or all of the windows of the Demised Premises as may be necessary for
the operation of Tenant's telecommunications business excluding changes
affecting the mechanical systems, on the following conditions, and providing
such changes will not result in a violation of or require a change in the
Certificate of Occupancy applicable to the Demised Premises:  (a) The outside
appearance, character or use of the Building shall not be affected, and no
Tenant's Changes shall weaken or impair the structural strength or, in the
opinion of Landlord, lessen the value of the Building; (b) No part of the
Building outside of the Demised Premises shall be physically affected, except
for Roof Space, generator space and equipment associated with it; (c) The proper
functioning of any of the mechanical, electrical, sanitary and other service
systems of the Building shall not be adversely affected; (d) In performing the
work involved in making such changes Tenant shall be bound by and observe all of
the conditions and covenants contained in this Article; (e) At the Expiration
Date, Tenant shall on Landlord's written request restore the Demised Premises to
their condition prior to the making of any of the changes permitted by this
Article, excluding the removal of demising walls, interior partitions and
ceilings installed pursuant to this Article, reasonable wear and tear excepted,
and Landlord shall be entitled to additional security pursuant to Article 15 for
the performance of Tenant's obligation; (f) At least thirty (30) days prior to
proceeding with any change (exclusive of changes in items constituting "Tenant's
Property" as defined in Article 13) Tenant shall submit to Landlord plans and
specifications for the work to be done, for Landlord's approval in writing,
which approval shall not be unreasonably withheld, and, if such change requires
approval by or notice to the lessor of a superior lease or the holder of a
superior mortgage, Tenant shall not proceed with the change until such approval
has been received, or such notice has been given, as the case may be, and all
applicable conditions and provisions of said superior lease or superior mortgage
with respect to the proposed change or alteration have been met or complied with
at Tenant's expense; and Landlord if it approves the change, will request such
approval or give such notice, as the case may be.  Any change for which approval
has been received shall be performed

                                      -23-
<PAGE>
 
strictly in accordance with the approved plans and specifications, and no
amendments or additions to such plans and specifications shall be made without
the prior written consent of Landlord. Tenant shall not be permitted to install
and make part of the Demised Premises any materials, fixtures or articles which
are subject to liens, conditional sales contracts, security agreements or
chattel mortgages, (nothing herein shall limit Tenant's right to subject
Tenant's trade fixtures or personal property to any of the foregoing); and (g)
Tenant shall comply with all other terms and conditions of this Lease in
connection with Tenant's Changes.

    12.02  All Tenant's Changes shall at all times comply with laws, orders and
regulations of governmental authority having jurisdiction thereof, and all rules
and regulations of Landlord and Tenant, at its expense, shall obtain all
necessary  governmental permits and certificates for the commencement and
prosecution of Tenant's Changes and for final approval thereof upon completion,
and shall cause Tenant's Changes to be performed in compliance therewith and
with all applicable requirements of insurance bodies, and in good and first
class workmanlike manner, using materials and equipment at least equal in
quality and class to the original installations of the Building.  Tenant's
Changes shall be performed in such manner as not to interfere with the occupancy
of any other tenant in the Building nor delay, or impose any additional expense
upon Landlord in the construction, maintenance or operation of the Building, and
shall be performed by contractors or mechanics approved by Landlord which
approval shall not be unreasonably withheld or delayed and in accordance with
the Building Rules and Regulations for Trades Conducting Operations, attached
hereto as Exhibit C-1 and Insurance Requirements for Trades Conducting
Operations in the Building, attached hereto as Exhibit C-2.  Throughout the
performance of Tenant's Changes, Tenant, at its expense, shall carry, or cause
to be carried, workmen's compensation insurance in statutory limits, and general
liability insurance for any occurrence on, in or about the Building, in which
Landlord and its managing agent shall be named as parties insured, in such
limits as Landlord may reasonably prescribe (but not less than those specified
in Section 16.02), with insurers reasonably satisfactory to Landlord.  Tenant
shall furnish Landlord with reasonably satisfactory evidence that such insurance
is in effect at or before the commencement of Tenant's Changes and, on request,
at reasonable intervals thereafter during the continuance of Tenant's Changes.
No Tenant's Changes shall involve the removal of any fixtures, equipment or
other property in the Demised Premises which are not "Tenant's Property" (as
defined in Article 13), unless Landlord's prior written consent is first
obtained and unless such fixtures, equipment or other property shall be promptly
replaced, at Tenant's expense and free of superior title, liens and claims, with
fixtures, equipment or other property (as the case may be) of like utility and
at least equal value (which replaced fixtures, equipment or other property shall
thereupon become the property of Landlord), unless Landlord shall otherwise
consent in writing.

    12.03  Tenant, at its expense, and with diligence and dispatch, shall
procure the cancellation or discharge of all notices of violation arising from
or otherwise connected with Tenant's Changes which shall be issued by the
appropriate department of the municipality in which the Building is located or
any other public authority having jurisdiction.  Tenant shall defend, indemnify
and save harmless Landlord against any and all mechanics and other liens in
connection with Tenant's Changes, repairs or installations, including but not
limited to the liens of any conditional sales of, or chattel mortgages upon, any
materials, fixtures, or articles so installed in and constituting part of the

                                      -24-
<PAGE>
 
Demised Premises and against all costs, attorney's fees, fines, expenses and
liabilities reasonably incurred in connection with any such lien, conditional
sale or chattel mortgage or any action or proceeding brought thereon.  Tenant,
by bonding or otherwise, at its expense, shall procure the satisfaction or
discharge of all such liens within thirty (30) days of the filing of such lien
against the Demised Premises or the Building.  If Tenant shall fail to cause
such lien to be discharged within the period aforesaid, then, in addition to any
other right or remedy, Landlord may, but shall not be obligated to, discharge
the same either by paying the amount claimed to be due or by procuring the
discharge of such lien by deposit or by bonding proceedings, and in any such
event Landlord shall be entitled, if Landlord so elects, to compel the
prosecution of any action for the foreclosure of such lien by the lienor and to
pay the amount of the judgment in favor of the lienor with interest, costs and
allowances.  Any amount so paid by Landlord and all costs and expenses incurred
by Landlord in connection therewith, together with interest thereon at the
lesser of the maximum permitted by law or 1 1/2% per month or portion thereof
from the respective dates of Landlord's making of the payment or incurring of
the cost and expense shall constitute additional rent payable by Tenant under
this Lease and shall be paid by Tenant within thirty (30) days of bill.  If
Tenant makes any such payment it shall not be entitled to any set-off against
rent due hereunder.  Tenant agrees that it will not at any time prior to or
during the Term, either directly or indirectly, use any contractors, labor or
materials in the Demised Premises, if the use of such contractors, labor or
materials would, in the Landlord's reasonable judgment, create any difficulty
with other contractors or labor engaged by Tenant or Landlord or would in any
way disturb harmonious labor relations in the construction, maintenance or
operation of the Building or any part thereof or any other building owned or
operated by Landlord or any affiliate of Landlord.

    12.04  If Tenant requires Landlord to perform work during other than Regular
Working Hours, or if Tenant desires to perform work through its contractors,
agents or employees during other than Regular Working Hours, Tenant shall pay as
additional rent, the reasonable actual out-of-pocket cost of employing such
additional help as shall be required under the rules and regulations of unions
employed in connection with the Building.  Payment shall be made by Tenant to
Landlord within thirty (30) days after being billed therefor, together with
reasonable substantion of such costs.

    12.05  In the event Landlord does not perform the work for Tenant, Tenant
shall pay to Landlord a supervisory fee (which shall include the cost of review
of the proposed Tenant's Changes) equal to Landlord's actual out-of-pocket
expenses for such supervision.


                        ARTICLE 13 -- TENANT'S PROPERTY

    13.01  All fixtures, equipment, improvements and appurtenances attached to
or built into the Demised Premises including without limitation demising walls,
ceiling and flooring, shall be deemed the property of Landlord and shall not be
removed by Tenant except as hereinafter in this Article expressly provided.

    13.02  All fixtures, furnishings and equipment, whether or not attached to
or built into the Demised Premises, which are installed in the Demised Premises
by or for the account of Tenant, may be removed by it at any time during the
Term; provided that if any of Tenant's Property is removed, Tenant shall repair
or pay the cost of repairing any damage to the Demised Premises or to the
Building resulting from such removal.  Any fixtures, equipment or other

                                      -25-
<PAGE>
 
property for which Landlord shall have granted any allowance to the Tenant as a
credit or substitution in kind shall not be deemed to have been installed by or
for the account of the Tenant without expense to Landlord, and shall not be
considered Tenant's Property. Landlord shall not be obligated to return and/or
reinstall any partitions supplied to Tenant which are returned by Tenant to
Landlord due to enlargement, reduction or change in the Demised Premises.

    13.03  At or before the expiration of this Lease, Tenant shall remove, at
its expense, from the Demised Premises, all of Tenant's Property and shall
repair any damage and make any replacements to the Demised Premises or the
Building resulting from or necessitated by such removal, and shall pay all other
costs of such removal.

    13.04  Any items of Tenant's Property which shall remain in the Demised
Premises after the expiration of this Lease, may, at the option of the Landlord,
be deemed to have been abandoned, and in such case either may be retained by
Landlord as its property or may be disposed of, without accountability to Tenant
in such manner as Landlord may see fit.  Tenant agrees to reimburse Landlord for
the costs of removal and for the cost of repairing any damage to the Demised
Premises or the Building arising out of Tenant's failure to remove Tenant's
Property pursuant to the terms of this Lease.


                     ARTICLE 14 -- REPAIRS AND MAINTENANCE

    14.01  Tenant shall take good care of the Demised Premises and the fixtures
and appurtenances therein, and at its sole cost and expense shall make all
repairs thereto, as and when needed to preserve them in good working order and
condition except as otherwise provided in Section 14.02 hereof.  In addition,
Tenant, at its expense, shall promptly make all repairs, ordinary or
extraordinary, interior or exterior, structural or otherwise, in and about the
Demised Premises and the Building as shall be required by reason of (i) the
performance or existence of work by Tenant necessary to suit the Demised
Premises to Tenant's initial occupancy or in connection with Tenant's Changes,
(ii) the installation, use or operation of Tenant's Property in the Demised
Premises, (iii) the moving of Tenant's Property in or out of the Building, or
(iv) the misuse or neglect of Tenant or any of its employees, agents or
contractors.  Tenant shall not be responsible, and Landlord shall be
responsible, for any repairs to the Demised Premises as are required by reason
of Landlord's neglect or other fault in the manner of performing any Work
provided for in Article 3 which Landlord is to perform in Tenant's Changes which
may be undertaken by Landlord for Tenant's account or are otherwise required by
reason of neglect or other fault of Landlord or its employees, agents or
contractors.

    14.02  Landlord shall keep and maintain the Building and its fixtures,
appurtenances, systems and facilities (including the heating, ventilating and
air-conditioning systems and the central or core elevator and plumbing systems),
serving the Demised Premises, in good working order, condition and repair and
shall make all structural repairs, interior and exterior, except as indicated in
the second sentence of Section 14.01, as and when needed in the Building, except
for those repairs for which Tenant is responsible pursuant to any other
provisions of this Lease, and subject to all other provisions of this Lease,
including but not limited to the provisions of Article 22. Landlord to maintain
building as first class office building - in compliance with laws including ADA.

                                      -26-
<PAGE>
 
    14.03  Except as expressly otherwise provided in this Lease, except for
gross negligence or wilful misconduct of Landlord, its agents, employees or
contractors, Landlord shall have no liability to Tenant by reason of any
inconvenience, annoyance, interruption or injury to business arising from
Landlord or any tenant making any repairs or changes or performing maintenance
services, whether or not Landlord is required or permitted by this Lease or by
law to make such repairs or changes or to perform such services in or to any
portion of the Building or Demised Premises, or in to the fixtures, equipment or
appurtenances of the Building or the Demised Premises, provided that Landlord
shall be reasonably diligent with respect thereto and shall perform such work,
except in case of emergency, at times reasonably convenient to Tenant and
otherwise in such manner and to the extent practical as will not unreasonably
interfere with Tenant's use and occupancy of the Demised Premises.

    14.04  When used in this Lease the term "repair" shall be deemed to include
restoration and replacements as may be necessary to achieve and/or maintain good
working order and condition.

                        ARTICLE 15 -- SECURITY DEPOSIT

    Tenant shall not be required to deposit any security at this time.  However,
in the event that Tenant shall fail to pay Rent when due, beyond any applicable
grace period, on two (2) occasion during any twelve (12) consecutive month
period of the Term of this Lease, then, Tenant shall deposit with Landlord an
amount equal to twice the then applicable monthly Fixed Rent as security for the
punctual performance by Tenant of each and every obligation of it under this
Lease, including the restoration of the Premises pursuant to Article 12.01.  In
the event of any default by Tenant not cured within applicable grace period,
Landlord may apply or retain all or any part of the security to cure the default
or to reimburse Landlord for any sum which Landlord may spend by reason of the
default.  In the case of every such application or retention Tenant shall,
within five (5) days of notice, pay to Landlord the sum so applied or retained
which shall be added to the Security Deposit so that the same shall be restored
to its original amount.  If at the end of the Term Tenant shall not be in
default under this Lease, the Security Deposit, or any balance thereof, shall be
returned to Tenant, within thirty (30) days after the Expiration Date.  In the
event of a sale of the land and Building or leasing of the Building, of which
the Demised Premises form a part, Landlord shall have the right to transfer the
security to the vendor or lessee and Landlord shall thereupon be released by
Tenant from all liability for the return of such security; and Tenant agrees to
look to the new Landlord solely for the return of said security; and it is
agreed that the provision hereof shall apply to every transfer or assignment of
the security to a new Landlord.  Tenant further covenants that it will not
assign or encumber or attempt to assign or encumber the monies deposited herein
as security and neither the Landlord nor its successors or assign shall be bound
by any such assignment, encumbrance, attempted assignment or attempted
encumbrance.


                            ARTICLE 16 -- INSURANCE

    16.01  Tenant shall not violate, or permit the violation of, any condition
imposed by the standard fire insurance policy then issued for office Buildings
in the area in which the Building is located and shall not do, or permit
anything to be done, or keep or permit anything to be kept in the Demised
Premises which would increase the fire or other casualty insurance rate on the
Building

                                      -27-
<PAGE>
 
or the property therein over the rate which would otherwise than be in effect
(unless Tenant pays the resulting increased amount of premium) or which would
result in insurance companies of good standing refusing to insure the Building
or any of such property in amounts and at normal rates reasonably satisfactory
to Landlord. However, Tenant shall not be subject to liability or obligation
under this Section by reason of the proper use of the Demised Premises for the
Permitted Use.

    16.02  Tenant shall obtain and keep in full force and effect during the Term
at its own cost and expense, Public Liability insurance, such insurance to
afford protection in an amount of not less than $1,000,000.00 for injury or
death to any one person, $3,000,000.00 for injury or death arising out of any
one occurrence, and $500,000.00 for damage to property, protecting the Landlord
and the Tenant as insureds against any and all claims for personal injury, death
or property damage occurring in, upon, adjacent, or connected with the Demised
Premises and any part thereof.  Said insurance is to be written by insurance
companies admitted to do business in the State of New Jersey which shall be
reasonably satisfactory to the Landlord.  The original insurance policies or
appropriate certificates shall be deposited with Landlord together with any
renewals, replacements or endorsements to the end that said insurance shall be
in full force and effect for the benefit of the Landlord during the Term.  In
the event Tenant shall fail to procure and place such insurance, the Landlord
may, but shall not be obligated to, procure and place same, in which event the
amount of the premium paid shall be paid by Tenant to Landlord within thirty
(30) days of demand and shall in each instance be collectible on the first day
of the month or any subsequent month following the date of payment by Landlord,
in the same manner as though, and same shall be considered to be additional rent
reserved hereunder.

    16.03  In the event that any dispute should arise between Landlord and
Tenant concerning insurance rates, a schedule or "make up" of rates for the
Building or the Demised Premises, as the case may be, issued by the Fire
Insurance Rating Organization of New Jersey or other similar body making rates
for fire insurance and extended coverage for the premises concerned, shall be
presumptive evidence of the facts therein stated and of the several items and
charges in the fire insurance rates with extended coverage then applicable to
such premises.

    16.04  Each party agrees to use its best efforts to include in each of its
insurance policies insuring the Building and Landlord's property therein and
rental value thereof, in the case of Landlord and insuring Tenant's Property and
business interest in the Demised Premises (business interruption insurance) in
the case of Tenant, against loss, damage or destruction by fire or other
casualty, a waiver of the insurer's right of subrogation against the other
party, or if such waiver should be unobtainable or unenforceable (a) an express
agreement that such policy shall not be invalidated if the insured waives the
right of recovery against any party responsible for a casualty covered by the
policy before the casualty or (b) any other form of permission for the release
of the other party.  If such waiver, agreement or permission shall not be, or
shall cease to be, obtainable without additional charge or at all, the insured
party shall so notify the other party promptly after learning thereof.  In such
case, if the other party shall so elect and shall pay the insurer's additional
charge therefore, such waiver, agreement or permission shall be included in the
policy, or the other party shall be named as an additional insured in the
policy, but not the loss payee.  Each such policy which shall so name a party
hereto as an additional insured shall contain

                                      -28-
<PAGE>
 
agreements by the insurer that the policy will not be cancelled without at least
twenty (20) days prior notice to both insureds and that the act or omission of
one insured will not invalidate the policy as to the other insured. Any failure
by Tenant, if named as an additional insured promptly to endorse to the order of
Landlord, without recourse, any instrument for the payment of money under or
with respect to the policy of which Landlord is the owner or original or primary
insured, shall be deemed a default under this Lease.

    16.05  Each party hereby releases the other party with respect to any claim
(including a claim for negligence) which it might otherwise have against the
other party for loss, damage or destruction with respect to its property
(including rental value or business interruption) occurring during the Term and
with respect and to the extent to which it is insured under a policy or policies
containing a waiver of subrogation or permission to release liability or naming
the other party as an additional insured as provided in Sections 16.04.  If
notwithstanding the recovery of insurance proceeds by either party for loss,
damage or destruction of its property (or rental value or business interruption)
the other party is liable to the first party with respect thereto or is
obligated under this Lease to make replacement, repair or restoration or
payment, then provided the first party's right of full recovery under its
insurance policies is not thereby prejudiced or otherwise adversely affected,
the amount of the net proceeds of the first party's insurance against such loss,
damage or destruction shall be offset against the second party's liability to
the first party therefor, or shall be made available to the second party to pay
for replacement, repair or restoration, as the case may be.

    16.06  The waiver of subrogation or permission for release referred to in
Section 16.04 shall extend to the agents of each party and its and their
employees and, in the case of Tenant, shall also extend to all persons and
entities occupying, using or visiting the Demised Premises in accordance with
the terms of this Lease, but only if and to the extent that such waiver or
permission can be obtained without additional charge (unless such party shall
pay such charge).  The releases provided for in Section 16.05 shall likewise
extend to such agents, employees and other persons and entities, if and to the
extent that such waiver or permission is effective as to them.   Nothing
contained in Section 16.05 shall be deemed to relieve either party of any duty
imposed elsewhere in this Lease to repair, restore or rebuild or to nullify any
abatement of rents provided for elsewhere in this Lease.  Except as otherwise
provided in Section 16.02, nothing contained in Section 16.04 and 16.05 shall be
deemed to impose upon either party any duty to procure or maintain any of the
kinds of insurance referred to therein or any particular amounts or limits of
any such kinds of insurance.


                   ARTICLE 17 -- SUBORDINATION, ATTORNMENT,
                        NOTICE TO LESSOR AND MORTGAGEES

    17.01  Subject to Tenant's receipt of Non-Disturbance Agreement in the
substantially the form of Exhibit E attached hereto, which shall be delivered to
Tenant within sixty (60) days of the signing of this Lease by all parties, this
Lease, and all rights of Tenant hereunder, are and shall be subject and
subordinate in all respects to all present and future ground leases, over-riding
leases and underlying leases and/or grants of terms of the land and/or the
Building or the portion thereof in which the Demised Premises are located in
whole or in part now or hereafter existing ("superior

                                      -29-
<PAGE>
 
leases") and to all mortgages and Building loan agreements, which may now or
hereafter affect the land and/or the Building and/or any of such leases
("superior mortgages") whether or not the superior leases or superior mortgages
shall also cover other lands and/or Buildings, to each and every advance made or
hereafter to be made under the superior mortgages, and to all renewals,
modifications, replacements and extensions of the superior leases and superior
mortgages and spreaders, consolidations and correlations of the superior
mortgages. This Section shall be self-operative and no further instrument of
subordination shall be required. In confirmation of such subordination, Tenant
shall promptly execute and deliver at its own cost and expense any instrument,
in recordable form if required, that Landlord, the lessor of any superior lease
or the holder of any superior mortgage or any of their respective successors in
interest may reasonably request to evidence such subordination, and Tenant
hereby constitutes and appoints Landlord attorney-in-fact for Tenant to execute
any such instrument for and on behalf of Tenant, provided they have entered into
Subordination, Non-Disturbance and Attornment Agreement.

    17.02  In the event that the lessor of a superior lease or the holder of a
superior mortgage shall succeed to the rights of the Landlord under this lease,
whether through possessory or foreclosure action or proceeding or through
delivery of a new lease, then at the request of any such party, the Tenant shall
attorn to and recognize such party as its Landlord under this Lease.  In any
such event, this Lease shall continue in full force and effect as if it were a
direct lease between such party and the Tenant upon all of the terms, covenants
and conditions set forth in this Lease and shall be applicable after such
attornment, except that such party shall not (a) be obligated to perform any
work in the Building, except such obligations of Landlord to operate, maintain
and repair the Building and its systems including the Demised Premises or
prepare them for occupancy; (b) be obligated to repair, replace, rebuild or
restore the Building, or the Demised Premises in the event of damage or
destruction, beyond such repair, replacement, rebuilding or restoration as can
reasonably be accomplished from the net proceeds of insurance actually received
by, or made available to, such party; (c) be liable for any previous act or
omission by Landlord; (d) be subject to any liability or offset which shall
theretofore accrue to the Tenant against Landlord; (e) be bound by any previous
modification or extension of this Lease unless filed with such party and made at
arms length, in good faith and in the honest exercise of reasonable business
judgment; (f) be bound by any previous pre-payment of more than one month's
fixed rent or other charge, or (g) be bound by any cancellation or surrender of
this Lease or any eviction of the Tenant by Landlord unless made at arms length,
in good faith and in the honest exercise of reasonable business judgment.

    17.03  Tenant agrees to waive the provisions of any statute or rule or law
now or hereafter in effect which may give or purport to give Tenant any right of
election to terminate this Lease or to surrender possession of the Demised
Premises in the event a superior lease is terminated or a superior mortgage is
foreclosed, and that unless and until said lessor, or holder, as the case may
be, shall elect to terminate this Lease, this Lease shall not be affected in any
way whatsoever by any such proceeding or termination, and Tenant shall take no
steps to terminate this Lease without giving written notice to said lessor under
the superior lease, or holder of a superior mortgage and a reasonable
opportunity to cure (without such lessor or holder being obligated to cure), any
default on the part of the Landlord under this Lease.

                                      -30-
<PAGE>
 
               ARTICLE 18 -- ASSIGNMENT, MORTGAGING, SUBLETTING

    18.01  Neither this Lease nor the Term and estate hereby granted, nor any
part hereof or thereof, nor the interest of Tenant in any sublease or the
rentals thereunder, shall be assigned, mortgaged, pledged, encumbered or
otherwise transferred by Tenant by operation of law or otherwise, and neither
the Demised Premises nor any part thereof, shall be encumbered in any manner by
reason of any act or omission on the part of the Tenant or anyone claiming under
or through Tenant, or shall be sublet or be used or occupied or permitted to be
used or occupied, or utilized for desk space or for mailing privileges, by
anyone other than Tenant or for any purpose other than as permitted by this
Lease, without the prior written consent of Landlord in every case, except as
expressly otherwise provided in this Article.

    18.02  If this Lease be assigned, whether or not in violation of the
provisions of this Lease, Landlord may collect rent from the assignee.  If the
Demised Premises or any part thereof be sublet or be used or occupied by anybody
other than Tenant, whether or not in violation of this Lease, Landlord may,
after default by Tenant, and expiration of Tenant's time to cure such default,
collect rent from the subtenant or occupant.  In either event, Landlord may
apply the net amount collected to the rents herein reserved, but no such
assignment, subletting, occupancy or collection shall be deemed a waiver of any
of the provisions of Section 18.01, or the acceptance of the assignee, subtenant
or occupant as tenant, or a release of Tenant from the further performance by
Tenant of Tenant's obligations under this Lease.  The consent by Landlord to
assignment, mortgaging or subletting, or use or occupancy by others shall not be
considered to relieve Tenant from obtaining the express written consent of
Landlord to any other or further assignment, mortgaging, or subletting or use or
occupancy by others not expressly permitted by this Article.  Tenant agrees to
pay to Landlord reasonable counsel fees incurred by Landlord in connection with
any proposed assignment of Tenant's interest in this Lease or any proposed
subletting of the Demised Premises or any part thereof, not to exceed $2,000.00
per request.  References in this Lease to use or occupancy by others, that is
anyone other than Tenant, shall not be construed as limited to subtenants and
those claiming under or through Tenant, immediately or remotely.

    18.03  Tenant may, upon written notice to Landlord, but without Landlord's
written consent, permit any corporations or other business entities which (i)
control, are controlled by, or are under common control with Tenant, (ii)
resulting from a merger or consolidation with Tenant, (iii) an entity succeeding
substantially to all of the business and assets of Tenant at the Demised
Premises, or (iv) a public offering of shares of Tenant or sale of shares
(herein called "related entity") to use the whole or part of Demised Premises
for any purposes permitted to Tenant or to sublet or assign all or part of the
premises to a related entity, subject however to compliance with Tenant's
obligations under the Lease.  Such use shall not be deemed to release, relieve,
discharge or modify any of Tenant's obligations hereunder.

    18.04  Other than in accordance with the provisions of Section 18.03, with
respect to any proposed assignment of this Lease or proposed subletting of all
or a portion of the Demised Premises:

    (A) Tenant shall submit to the Landlord a request for consent to such
assignment or sublease together with the name and address of the proposed
assignee or sublessee and such information as to its financial responsibility
and standing as Landlord may require.  Upon receipt of such request and upon the
furnishing of such

                                      -31-
<PAGE>
 
information by the Tenant, Landlord shall have the option to cancel and
terminate this Lease (i) completely, if the request was for an assignment of
this Lease or subletting of all of the Demised Premises, or (ii) if such request
was for a subletting of a portion of the Demised Premises, then with respect to
such portion.

    (B)  Landlord shall exercise such option to cancel and terminate by notice
in writing to that effect to Tenant within ten (10) days from receipt of
Tenant's request and the information set forth above, and Landlord's notice
shall set forth the date of cancellation, which date shall be no less than sixty
(60) nor more than ninety (90) days from the date of the service of Landlord's
notice. If such option is so exercised, and Tenant does not notify Landlord in
writing within five (5) days of Landlord's notice of such cancellation, then
upon such date of cancellation the Lease for the entire Demised Premises or
specified portion thereof, as the case may be, shall cease and terminate with
the same force and effect as though the date set forth in the notice were the
date set forth in this Lease as the expiration of the Term, and the Tenant shall
surrender possession of the entire Demised Premises, or portion thereof, as the
case may be, in accordance with the provisions of the Lease relating to
surrender of the Demised Premises at the expiration of the Term. If Landlord
exercises the option to cancel the Lease as to a portion of the Demised Premises
only, the terms of this Lease shall remain in full force as to the remainder of
the Demised Premises, for the balance of the Term, except to the extent that the
area of the Demised Premises is reduced with a proportionate reduction in rent.

    (C)  If Landlord does not exercise its option to cancel as aforementioned
than Tenant may assign or sublet all or a portion of the Demised Premises,
provided that Landlord has given its prior written consent, which shall not be
unreasonably withheld or delayed and provided further that: (i) the Tenant is
not then in default in curing a default for which Tenant shall have received
notice hereunder; (ii) the Demised Premises are to be used for the Permitted Use
only by a person, firm or corporation engaged in a lawful commercial business
(other than a business operating data processing machinery in the Demised
Premises larger than desk top size), but not for the practice of medicine, (iii)
such assignee or sublessee shall be financially responsible and of good
reputation; (iv) the business of such assignee or sublessees or the use to which
such Demised Premises shall be put shall not be violation of any restriction
against competition contained in any other lease to which Landlord is a party;
(v) the assignee or sublessee is not engaged in the containerized shipping
business or as a governmental agency of a communist agency and (vi) a duplicate
original of an instrument in writing assigning this Lease or subletting the
Demised Premises, duly executed by the assignor or sublessor and assignee or
sublessee, as the case may be, in recordable form, containing therein an
assumption by said assignee or an agreement by said sublessee to take subject to
(and an agreement by Tenant to remain liable to Landlord for) all the terms and
conditions of this Lease on the part of the Tenant to be performed.  In the
event the rental provided for in such assignment or sublease is in excess of the
rental in effect pursuant to this Lease, Landlord shall be aid such excess
monthly, less Tenant's reasonable expenses incurred in connection with such
assignment or sublease.

    (D)  The provisions of this Article 18 shall apply to each such proposed
subletting, none of which shall be effective until all of the foregoing shall
have been complied with.  Notwithstanding any subletting, Tenant and any future
sublessor shall remain liable for the full performance of all the terms and
conditions of this Lease on the part of the Tenant to be performed.

                                      -32-
<PAGE>
 
    18.05  Tenant shall not offer to assign or sublet either the entire Demised
Premises or a specified portion thereof to any other Tenant in the Building or
to any party in negotiations with Landlord to lease a portion of the Building.

    18.06  Tenant specifically agrees that it will not, at any time, without
Landlord's prior written consent which shall not be unreasonably withheld or
delayed, advertise or publicize in any way the availability of all or part of
the Demised Premises, or list or publicly advertise the Demised Premises for
subletting, whether through a broker, agent, representative or otherwise.

    18.07  Landlord acknowledges that Tenant's business to be conducted in the
Demised Premises requires the installation in the Demised Premises of certain
communications equipment by telecommunications customers of Tenant ("Customers")
in order for such Customers to interconnect with Tenants Terminal facilities.
Landlord agrees that no consent shall be required for any license agreement or
"co-location agreement" between Tenant or any such Customer for the purposes of
permitting such a telecommunications connection, so long as (i) such Customer
agrees in writing to comply with all obligations of Tenant under this Lease to
the extent relating to the portion of the Demised Premises in question, and (ii)
each such license or co-location agreement is in writing, is consistent with the
provisions of this Lease.  Co-location shall not be deemed under any
circumstances, a sublet or assignment of the Demised Premises.


              ARTICLE 19 -- COMPLIANCE WITH LAWS AND REQUIREMENTS
                  OF PUBLIC AUTHORITIES:  RULES & REGULATIONS

    19.01  Tenant shall promptly notify Landlord of any written notice it
receives of the violation of any law or requirements which shall, with respect
to the Building or the Demised Premises or the use and occupation thereof or the
abatement of any nuisance, impose any violation, order or duty on Landlord or
Tenant, arising from (i) Tenant's use of the Demised Premises, (ii) the manner
of conduct of Tenant's business or operation of its installations, equipment or
other property therein, (iii) any cause or condition created by or at the
instance of Tenant, or (iv) breach of any of Tenant's obligations hereunder.

    19.02  Tenant and its employees and agents shall faithfully observe and
comply with the Rules and Regulations annexed hereto as Exhibit "B", and such
reasonable changes therein (whether by modification, elimination or addition) as
Landlord at any time or times hereafter may make and communicate in writing to
Tenant, which do not unreasonably affect the conduct of Tenant's business in the
Demised Premises; provided, however, that in case of any conflict or
inconsistency between the provisions of this Lease and any Rules and Regulations
changed subsequent to the date of this Lease the provisions of this Lease shall
control.

    19.03  Nothing in this Lease contained shall be construed to impose upon
Landlord any duty or obligation to Tenant to enforce the Rules and Regulations
or the terms, covenants or conditions in any other lease, as against any other
tenant unless requested to do so by Tenant, but Landlord shall not be liable to
Tenant for violation of the same by any other tenant or its employees, agents

                                      -33-
<PAGE>
 
or visitors. Landlord shall not enforce the Rules and Regulations in a
discriminatory manner.


                         ARTICLE 20 -- QUIET ENJOYMENT

     20.01  Landlord covenants that if, and so long as, Tenant pays all of the
Fixed Rent and additional rent due hereunder, and keeps and performs each and
every covenant, agreement, term, provision and condition herein contained on the
part and on behalf of Tenant to be kept and performed, Tenant shall quietly
enjoy the Demised Premises without hinderance or molestation by Landlord or any
other person lawfully claiming the same, subject to the covenants, agreements,
terms, provisions and conditions of this Lease and to any superior leases and/or
superior mortgages.


                 ARTICLE 21 -- NON-LIABILITY & INDEMNIFICATION

     21.01  Neither Landlord nor any agent or employee of Landlord shall be
liable to Tenant, its employees, agents, contractors and licensees, and Tenant
shall hold Landlord harmless from any injury or damage to Tenant or to any other
persons for any damage to, or loss (by theft or otherwise) of, any property of
Tenant and/or of any other person, irrespective of the cause of such injury,
damage or loss, except to the extent caused by or due to the gross negligence of
Landlord, its agents or employees without contributory negligence on the part of
Tenant.  Landlord shall not be liable in any event for loss of, damage to, any
property entrusted to any of Landlord's employees or agents by Tenant without
Landlord's specific written consent.

     21.02  Tenant shall defend, indemnify and save harmless Landlord and its
agent and employees against and from all liabilities, obligations, damages,
penalties, claims, costs, charges and expenses, including reasonable experts'
and attorneys' fees, which may be imposed upon or incurred by or asserted
against Landlord and/or its agents by reason of any of the following occurring
during the Term, or during any period of time prior to the Commencement Date
that Tenant may have been given access to or possession of all or any part of
the Demised Premises:  (a) any work or thing done in on or about the Demised
Premises or any part thereof by or at the instance of Tenant, its agents,
contractors, subcontractors, servants, employees, licensees or invitees; (b) any
negligence or otherwise wrongful act or omission on the part of Tenant or any of
its agents, contractors, subcontractors, servants, employees, subtenants,
licensees, or invitees; (c) any accident, injury or damage to any person or
property occurring in on or about the Demised Premises or any part thereof, or
vault, passageway or space adjacent thereto; (d) any failure on the part of
Tenant to perform or comply with any of the covenants, agreements, terms,
provisions, conditions or limitations contained in this Lease on its part to be
performed or complied with; and (e) any accident, injury or damage to any person
or property arising out of the installation, operation or maintenance of the
Tenant's emergency stand-by generator and related items and Tenant's antennae
and air cooling equipment, except if such is caused by Landlord's agents,
contractors, subcontractors, servants or employees, licensees and invitees.  In
case any action or proceeding is brought against Landlord by reason of any such
claim, Tenant upon written notice from Landlord shall at Tenant's expense resist
or defend such action or proceeding by Counsel approved by Landlord in writing,
which approval Landlord shall not unreasonably withhold.

                                      -34-
<PAGE>
 
     21.03  Whenever either party shall be obligated under the terms of this
Lease to indemnify the other party, the indemnifying party may select legal
counsel (subject to the consent of the indemnified party, which consent shall
not be unreasonably withheld) and shall keep the indemnified party fully
appraised at all times of the status of such defense.  Legal counsel of the
insurer for either party is hereby deemed satisfactory to both parties.

     21.04  Except as otherwise expressly provided herein, this Lease and the
obligations of Tenant to pay rent hereunder and perform all of the other
covenants, agreements, terms, provisions and conditions hereunder on the part of
Tenant to be performed shall in no wise be affected, impaired or excused because
Landlord is unable to fulfill any of its obligations under this Lease or is
unable to supply or is delayed in supplying any service, express or implied, to
be supplied or is unable to make or is delayed in supplying any equipment or
fixtures if Landlord is prevented or delayed from so doing by reason of any
Unavoidable Delays, as defined in Section 3.02 hereof; provided that Landlord
shall in each instance exercise reasonable diligence to effect performance when
and as soon as possible.  However, nothing contained in this Section shall be
deemed to extend or otherwise modify or affect any of the time limits and
conditions set forth in Section 22.03.


                     ARTICLE 22 -- DESTRUCTION AND DAMAGE

     22.01  If the Demised Premises and/or access thereto shall be partially or
totally damaged or destroyed by fire or other casualty, then, Landlord shall,
subject to its rights under Section 22.03 hereof, repair the damage and restore
and rebuild the Demised Premises and/or access thereto as nearly as may be
reasonably practical to its condition and character immediately prior to such
damage or destruction, with reasonable diligence after notice to it of the
damage or destruction.

     22.02  If the Demised Premises and/or access thereto shall be partially or
totally damaged or destroyed by fire or other casualty, the rents payable
hereunder shall be abated to the extent that the Demised Premises shall have
been rendered untenantable from the date of such damage or destruction to the
date the damage shall be substantially repaired or restored or rebuilt.  Should
Tenant reoccupy a portion of the Demised Premises during the period that the
repair, restoration, or rebuilding is in progress and prior to the date that the
same are made completely tenantable, rents allocable to such portion shall be
payable by Tenant from the date of such occupancy to the date the Demised
Premises are made tenantable.

     22.03  In case of substantial damage or destruction of the Demised
Premises, Tenant may terminate this Lease by notice to Landlord, if Landlord has
not completed the making of required repairs and restored and rebuilt the
Demised Premises and/or access thereto within 12 months from the date of such
damage or destruction, and such additional time after such date (but in no event
exceed 9 months) as shall equal the aggregate period Landlord may have been
delayed in doing so by adjustment of insurance or Unavoidable Delays.

     In case the Building shall be so damaged by such fire or other casualty
that substantial renovation, reconstruction or demolition of the Building shall,
in Landlord's opinion, be required (whether or not the Demised Premises shall
have been damaged by such fire or other casualty), then Landlord may, at its
option, terminate this Lease and the Term and estate hereby granted, by
notifying Tenant

                                      -35-
<PAGE>
 
of such termination, within sixty (60) days after the date of such damage. If at
any time prior to Landlord giving tenant the aforesaid notice of termination or
commencing the repair and restoration pursuant to Section 22.01, the holder of a
superior mortgage or the lessor of a superior lease or any person claiming under
or through the holder of such superior mortgage or the lessor of such superior
lease takes possession of the Building through foreclosure or otherwise, such
holder, lessor, or person shall have a further period of sixty (60) days from
the date of so taking possession to terminate this Lease by appropriate written
notice to Tenant. In the event that such a notice of termination shall be given
pursuant to either of the next two preceding sentences, this Lease and the Term
and estate hereby granted shall expire as of the date of such termination with
the same effect as if that were the date hereinabove set for the expiration of
the Term, and the Fixed Rent and additional rent due and to become due hereunder
shall be apportioned as of such date if not earlier abated pursuant to Section
22.02. Nothing contained in this Section 22.03 shall relieve Tenant from any
liability to Landlord or to its insurers in connection with any damage to the
Demised Premises or the Building by fire or other casualty if Tenant shall be
legally liable in such respect.

     22.04  No damages, compensation or claim shall be payable by Landlord for
inconvenience, loss of business or annoyance arising from any repair or
restoration of any portion of the Demised Premises or of the Building pursuant
to this Article.  Landlord shall use its best efforts to effect such repair or
restoration promptly and in such manner as not unreasonably to interfere with
Tenant's use and occupancy.

     22.05  Landlord will not carry insurance of any kind on Tenant's Property,
and, except as provided by law or its breach of any of its obligations
hereunder, shall not be obligated to repair any damage thereto or replace the
same.

     22.06  The provisions of this Article shall be considered an express
agreement governing any case of damage or destruction of the Demised Premises by
fire or other casualty, and any statute or regulation providing for such a
contingency in the absence of, an express agreement, now or hereafter in force,
shall have no application in such case.

     22.07  Notwithstanding any of the foregoing provisions of this Lease if
Landlord or the lessor of any superior lease or the holder of any superior
mortgage shall be unable to collect all of the insurance proceeds (including
rent insurance proceeds) applicable to damage or destruction of the Demised
Premises or the Building by fire or other cause, by reason of some action or
inaction on the part of Tenant or any of its employees, agents or contractors,
then, without prejudice to any other remedies which may be available against
Tenant, the abatement of Tenant's rents provided for in this Article shall not
be effective to the extent of the uncollected insurance proceeds.


                         ARTICLE 23 -- EMINENT DOMAIN

     23.01  In the event that the land, Building or any part thereof, or the
Demised Premises or any part thereof, shall be taken in condemnation proceedings
or by the exercise of any right of eminent domain or by agreement between any
superior lessors and lessees and/or Landlord on the one hand and any
governmental authority authorized to exercise such right on the other hand,
Landlord shall be entitled to collect from any condemnor the entire

                                      -36-
<PAGE>
 
award or awards that may be made in any such proceeding without deduction
therefrom for any estate hereby vested in or owned by Tenant, to be paid out as
in this Article provided. Tenant hereby expressly assigns to Landlord all of its
right, title and interest in or to every such award (with the exception of that
portion of the award specifically allocated as Tenant's moving expenses, to the
extent that the same does not decrease Landlord's award) and also agrees to
execute any and all further documents that may be required in order to
facilitate the collection thereof by Landlord.

     23.02  At any time during the Term if title to the whole or substantially
all of the land, Building and/or Demised Premises shall be taken in by
condemnation proceedings or by the exercise of any right of eminent domain or by
agreement between any superior lessors and lessees and/or Landlord on the one
hand and any governmental authority authorized to exercise such right on the
other hand, this Lease shall terminate and expire on the date of such taking and
the Fixed Rent and additional rent provided to be paid by Tenant shall be
apportioned and paid to the date of such taking.

     23.03  However, if substantially all of the land or Building is not so
taken and if only a part of the entire Demised Premises shall be so taken, this
Lease nevertheless shall continue in full force and effect, except that either
party may elect to terminate this Lease if that portion of the Demised Premises
then occupied by Tenant shall be reduced by more than 25%, by notice of such
election to the other party given not later than thirty (30) days after (i)
notice of such taking is given by the condemning authority, or (ii) the date of
such taking, whichever occurs later. Upon the giving of such notice this Lease
shall terminate on the date of service of such notice and the Fixed Rent and
additional rent due and to become due, shall be prorated and adjusted as of the
date of the taking. If both parties fail to give such notice upon such partial
taking, and this Lease continues in force as to any part of the Demised Premises
not taken, the rents apportioned to the part taken shall be prorated and
adjusted as of the date of taking and from such date the Fixed Rent and
additional rent shall be reduced to the amount apportioned to the remainder of
the Demised Premises, and the Tenant's Share shall be recomputed to reflect the
number of square feet of Tenant's Floor Space remaining in the Demised Premises
in relation to the number of square feet of Total Building Floor Space remaining
in the Building.

     23.04  Notwithstanding the foregoing provisions of this Article and subject
to the interest of any mortgagees or lessor or grantor under any superior
mortgage or superior lease, Tenant shall be entitled to appear, claim, prove and
receive in the proceedings relating to any taking mentioned in the preceding
Sections of this Article, such portion of each award made therein as represents
the then value of Tenant's Property.

     23.05  In the event of any such taking of less than the whole of the
Building which does not result in a termination of this Lease, Landlord, at its
expense, shall proceed with reasonable diligence to repair, alter and restore
the remaining part of the Building and the Demised Premises to substantially the
same condition as it was in immediately prior to such taking to the extent that
the same may be feasible, so as to constitute a tenantable Building and Demised
Premises, providing that Landlord's liability under this Section shall be
limited to the amount received by Landlord as an award arising out of such
taking.

                                      -37-
<PAGE>
 
                            ARTICLE 24 -- SURRENDER

    24.01  On the last day of the Term, or upon any earlier termination of this
Lease, or upon any re-entry by Landlord upon the Demised Premises, Tenant shall
quit and surrender the Demised Premises to the Landlord broom clean, in good
order, condition and repair except for ordinary wear and tear and damage by fire
or other insured casualty, restored as provided in Section 12.01.

    24.02  Prior to such surrender, Tenant shall (a) remove Tenant's Property
subject to the provisions of Article 13 hereof, (b) at Landlord's request,
remove from the Demised Premises all improvements, alterations, additions,
fixtures and equipment including Tenant's Work attached hereto as Exhibit C, and
the emergency standby generator and diesel fuel tank referred to in Article 2,
whether such work was performed by Tenant or by Landlord on Tenant's behalf, and
whether such additional work consisted of extra or special work or additional
items or quantities of Building standard work, and (c) at Landlord's request,
repair any damage and make any replacements to the Building or the Demised
Premises resulting from or necessitated by such removal, and restore those parts
of the Demised Premises from which the removal referred to in subparagraphs (a)
and (b) above occurred, to a condition which will blend with and be comparable
to adjacent areas.  Tenant's removal and repair obligations hereunder with
respect to the Demised Premises shall extend to the core area or any other part
of the Building where any additional work was performed by or on behalf of
Tenant.  If Tenant shall fail to perform as provided in this Section 24.02,
Landlord shall have the right to do so at Tenant's cost and expense, without
further notice or demand upon Tenant, and Tenant shall indemnify Landlord
against all loss or liability resulting therefrom, including, without
limitation, any delay in granting occupancy of the Demised Premises to a future
occupant.


                    ARTICLE 25 -- CONDITIONS OF LIMITATION

    25.01  This Lease and the estate hereby granted are subject inter alia to
the limitation that whenever Tenant shall make an assignment for the benefit of
creditors, or shall file a voluntary petition under any bankruptcy or insolvency
law, or an involuntary petition alleging an act of bankruptcy or insolvency is
filed against Tenant, or whenever a petition shall be filed by or against Tenant
seeking any reorganization, arrangement, composition, readjustment, liquidation,
dissolution or similar relief under any present or any future federal bankruptcy
act or any other present or future applicable federal, state or other statute or
law, or shall seek or consent to or acquiesce in the appointment of any trustee,
receiver or liquidator of Tenant or of all or any substantial part of its
properties, or whenever a permanent or temporary receiver of Tenant or of, or
for, the property of Tenant shall be appointed, or if Tenant shall plead
bankruptcy or insolvency as a defense in any action or proceeding, then,
Landlord, (a) at any time after receipt of notice of the occurrence of any such
event, or (b) if such event occurs without the acquiescence of Tenant, at any
time after the event continues for sixty (60) days, may give Tenant a notice of
intention to end the Term at the expiration of five (5) days from the service of
such notice of intention, and upon the expiration of said five (5) day period
Lease and the Term and estate hereby granted, whether or not the Term shall
theretofore have commenced, shall terminate with the same effect as if that day
were the Expiration Date, but Tenant shall remain liable for damages as provided
as in Article 27.

                                      -38-
<PAGE>
 
    25.02  This Lease and the Term and estate hereby granted and subject to the
further limitation that, (a) whenever Tenant shall default in the payment of any
installment of Fixed Rent, or in the payment of any additional rent, on any day
upon which the same shall be due and payable and such default shall continue for
ten (10) days after the giving of notice thereof by Landlord, or (b) whenever
Tenant shall do or permit anything to be done, whether by action or inaction,
contrary to any of Tenant's obligations hereunder, and if such situation shall
continue and shall not be remedied by Tenant within thirty (30) days after
Landlord shall have given to Tenant a notice specifying the same, or, in the
case of a happening or default which cannot with due diligence be cured within a
period of thirty (30) days and the continuance of which for the period required
for cure will not subject Landlord to the risk of criminal liability or
termination of any superior lease or foreclosure of any superior mortgage, if
Tenant shall not duly institute within such thirty (30) day period and promptly
and diligently prosecute to completion all steps necessary to remedy the same,
or (c) whenever any event shall occur or any contingency shall arise whereby
this Lease or any interest therein or the estate hereby granted or any portion
thereof or the unexpired balance of the Term hereof would, by operation of law
or otherwise, devolve upon or pass to any person, firm or corporation other than
Tenant, except as expressly permitted by Article 18; then in any such event
covered by subsections a, b or c of this Section 25.2 at any time thereafter,
Landlord may give to Tenant a notice of intention to end the Term of this Lease
at the expiration of three (3) days from the date of the service of such notice
of intention, and upon the expiration of said three (3) days this Lease and the
Term and the estate hereby granted, whether or not the Term shall theretofore
have commenced, shall terminate with the same effect as if that day were the
Expiration Date, but Tenant shall remain liable for damages as provided in
Article 27.

                     ARTICLE 26 -- RE-ENTRY BY LANDLORD --
                              DEFAULT PROVISIONS

    26.01  If this Lease shall terminate for any reason whatsoever, Landlord or
Landlord's agents and employees may, without further notice, immediately or at
any time thereafter, enter upon and re-enter the Demised Premises, or any part
thereof, and possess or repossess itself thereof either by summary dispossess
proceedings, ejectment or by any suitable action or proceeding at law, or by
agreement, or by force or otherwise, and may dispossess and remove Tenant and
all other persons and property from the Demised Premises without being liable to
indictment, prosecution or damages therefor, and may repossess the same, and may
remove any persons therefrom, to the end that Landlord may have, hold and enjoy
the Demised Premises and the right to receive all rental income again as and of
its first estate and interest therein.  The words "enter" or "re-enter",
"possess" or "repossess" as herein used, are not restricted to their technical
legal meaning.  In the event of the termination of this Lease, or of re-entry by
summary dispossess proceedings, ejectment or by any suitable action or
proceeding at law, or by agreement, or by force or otherwise by reason of
default hereunder on the part of Tenant, Tenant shall thereupon pay to Landlord
the Fixed Rent and additional rent due up to the time of such termination of
this Lease or of such recovery of possession of the Demised Premises by
Landlord, as the case may be, and shall also pay to Landlord damages as provided
in Article 27.

    26.02  In the event of any breach or threatened breach by Tenant of any of
the agreements, terms, covenants or conditions contained in this Lease, Landlord
shall be entitled to enjoin such

                                      -39-
<PAGE>
 
breach or threatened breach and shall have the right to invoke any right and
remedy allowed at law or in equity or by statute or otherwise as though re-
entry, summary proceedings, and other remedies were not provided for in this
Lease.

    26.03  Each right and remedy of Landlord provided for in this Lease shall be
cumulative and shall be in addition to every other right or remedy provided for
in this Lease or now or hereafter existing at law or in equity or by statute or
otherwise, and the exercise or beginning of the exercise by Landlord of any one
or more of the right or remedies provided for in this Lease or now or hereafter
existing at law or in equity or by statute or otherwise shall not preclude the
simultaneous or later exercise by Landlord of any or all other rights or
remedies provided for in this Lease or now or hereafter existing at law or in
equity or by statue or otherwise.

    26.04  If this Lease shall terminate under the provisions of Article 25, or
if Landlord shall re-enter the Demised Premises under the provisions of this
Article 26, or in the event of the termination of this Lease, or of re-entry, by
or under any summary dispossess or other proceeding or action or any provision
of law by reason of default hereunder on the part of Tenant, Landlord shall be
entitled to retain all monies, if any, paid by Tenant to Landlord, whether as
advance rent, security or otherwise, but such monies shall be credited by
Landlord against any Fixed Rent or additional rent due from Tenant under Article
27 or pursuant to law.


                             ARTICLE 27 -- DAMAGES

    27.01  If this Lease is terminated under the provisions of Article 25, or if
Landlord shall re-enter the Demised Premises under the provisions of Article 26
or in the event of the termination of this Lease, or of re-entry by summary
dispossess proceedings, ejectment or by any suitable action or proceeding at
law, or by agreement, or by force or otherwise, by reason of default hereunder
on the part of Tenant, Tenant shall pay to Landlord as damages, at the election
of Landlord, on demand either,

    (a)  a sum which at the time of such termination of this Lease or at the
time of any such re-entry by Landlord, as the case may be, represents the excess
of (1) the aggregate of the Fixed Rent and the additional rent payable hereunder
which would have been payable by Tenant (conclusively presuming the additional
rent to be the same as was payable for the year immediately preceding such
termination) for the period commencing with such earlier termination of this
Lease or the date of any such re-entry, as the case may be, and ending with the
expiration of the Term, had this Lease not so terminated or had Landlord not so
re-entered the Demised Premises over (2) the aggregate rental value (calculated
as of the date of such termination or re-entry) of the Demised Premises for the
same period, or,

    (b)  a sum equal to the Fixed Rent and the additional rent (as above
presumed) payable hereunder which would have been payable by Tenant had this
Lease not so terminated, or had Landlord not so re-entered the Demised Premises,
payable quarterly or otherwise upon the terms therefor specified herein
following such termination or such re-entry and until the expiration of the
Term, provided, however, that if Landlord shall relet the Demised Premises or
any portion or portions thereof during said period, Landlord shall credit Tenant
with the net rents such net rents to be determined by first deducting from the
gross rents as and when received by

                                     -40-
<PAGE>
 
Landlord from such reletting the expenses incurred or paid by Landlord in
terminating this Lease or in re-entering the Demised Premises and in securing
possession thereof, as well as the expenses of reletting, including altering and
preparing the Demised Premises or any portion or portions thereof for new
tenants, brokers' commissions, advertising expenses, attorneys' fees, and all
other expenses properly chargeable against the Demised Premises and the rental
therefrom; it being understood that any such reletting may be for a period
shorter or longer than the remaining Term of this Lease, but in no event shall
Tenant be entitled to receive any excess of such net rents over the sums payable
by Tenant to Landlord hereunder, nor shall Tenant be entitled in any suit for
the collection of damages pursuant to this Subsection to a credit in respect of
any net rents from a reletting, except to the extent that such net rents are
actually received by Landlord. If the Demised Premises or any part thereof
should be relet in combination with other space, then proper apportionment shall
be made of the rent received from such reletting and of the expenses of
reletting.

    If the Demised Premises or any part thereof be relet by Landlord for the
unexpired portion of the Term, or any part thereof, before presentation of proof
of such damages to any court, commission, or tribunal, the amount of rent
payable upon such reletting shall, prima facie, be the fair and reasonable
rental value for the Demised Premises or any part thereof or evidence of damage
for failure to collect any rent due upon any such reletting.

    27.02  Suit or suits for the recovery of such damages, or any installments
thereof, may be brought by Landlord from time to time at its election, and
nothing contained herein shall be deemed to require Landlord to postpone suit
until the date when the Term would have expired if it had not been so terminated
under the provision of Article 26, or under any provision of law, or had
Landlord not re-entered the Demised Premises.  Nothing herein contained shall be
construed to limit or preclude recovery by Landlord against Tenant of any sums
or damages to which, in addition to the damages particularly provided above,
Landlord may lawfully be entitled by reason of any default hereunder or
otherwise on the part of Tenant.  Nothing herein contained shall be construed to
limit or prejudice the right of the Landlord to prove and obtain as damages by
reason of the termination of this Lease or re-entry on the Demised Premises for
the default of Tenant under this Lease, an amount equal to the maximum allowed
by any statute or rule of law in effect at the time when, and governing the
proceedings in which, such damages are to be proved whether or not such amount
be greater, equal to, or less than any of the sums referred to Section 27.01.

    27.03  Anything in this Lease to the contrary notwithstanding, if Tenant
shall at any time be in default hereunder, and if Landlord shall institute an
action or summary proceeding against Tenant based upon such default, or if such
default results from non-payment of Fixed Rent or additional rent whether or not
such an action or proceeding is instituted, then the non-prevailing party shall
reimburse the prevailing party for the expense of attorneys' fees and
disbursements thereby incurred by the prevailing, so far as the same are
reasonable.


                             ARTICLE 28 -- WAIVERS

    28.01  Tenant, for itself, and on behalf of any and all persons claiming
through or under Tenant, including creditors of all kinds, does hereby waive and
surrender all right and privilege so far as 

                                      -41-
<PAGE>
 
is permitted by law, which they or any of them might have under or by reason of 
any present or future law, of the service of any notice of intention to re-enter
and also waives any and all right of redemption or re-entry or repossession in 
case Tenant shall be dispossessed or ejected by process of law, or in case of 
re-entry or repossession by Landlord, or in case of any expiration or 
termination of this Lease as herein provided.

     28.02  Tenant waives Tenant's rights, if any, to designate the items 
against which any payments made by Tenant are to be credited, and Tenant agrees 
that Landlord may apply any payments made by Tenant to any items against which 
any such payments shall be credited.

     28.03  Tenant waives Tenant's rights, if any, to assert a counterclaim in 
any summary proceeding brought by Landlord against Tenant, and Tenant agrees to 
assert any such claim against Landlord only by way of a separate action or 
proceeding.

     28.04  To the extent permitted by applicable law, Landlord and Tenant 
hereby waive trail by jury in any action, proceeding or counterclaim brought by 
either against the other on any matter whatsoever arising out of or in any way 
connected with this Lease, the relationship of Landlord and Tenant, or Tenant's 
use of occupancy of the Demised Premises, or any emergency or other statutory 
remedy with respect thereto.

     28.05  The provisions of Article 8 and 9 shall be considered express 
agreements governing the services to be furnished by Landlord, and Tenant agrees
that any laws and/or requirements of public authorities, now or hereafter in 
force, shall have no application in connection with any enlargement of 
Landlord's obligations with respect to such services.

                ARTICLE 29 -- NO OTHER WAIVERS OR MODIFICATIONS

     29.01  The failure of Landlord to insist on any one or more instances upon 
the strict performance of any one or more of the agreements, terms, covenants, 
conditions or obligations of this Lease, Exhibits and Riders thereto, or to 
exercise any right, remedy or election herein contained, shall not be construed 
as a waiver or relinquishment for the future of the performance of such one or 
more obligations of this Lease or of the right to exercise such election, but 
the same shall continue and remain in full force and effect with respect to any 
subsequent breach, act or omission. The manner of enforcement or the failure of 
Landlord to enforce any of the Rules and Regulations set forth herein, or 
hereafter adopted against the Tenant and/or any other tenant in the Building 
shall not be deemed a waiver of any such  Rules and Regulations. No executory 
agreement hereafter made between Landlord and Tenant shall be effective to 
change, modify, waive, release, discharge, terminate or affect an abandonment of
this Lease, in whole or in part, unless such executory agreement is in writing,
refers expressly to this Lease and is signed by the party against whom 
enforcement of the change, modification, waiver, release, discharge or 
termination or effectuation of the abandonment is sought.

     29.02  The following specific provisions of this Section shall not be
deemed to limit the generality of the foregoing provisions of this Article:

     (a)    no agreement to accept a surrender of all or any part of the Demised
Premises shall be valid unless in writing and signed by Landlord. The delivery 
of keys to an employee of Landlord or of

                                     -42-

    

<PAGE>
 
its agent shall not operate as a termination of this Lease or a surrender of the
Demised Premises. If Tenant shall at any time request Landlord to sublet the
Demised Premises for Tenant's account, Landlord or its agent is authorized to
receive said keys for such purposes without releasing Tenant from any of its
obligations under this Lease, and Tenant hereby releases Landlord from any
liability for loss or damage to any of Tenant's Property in connection with such
subletting.

     (b)    the receipt or acceptance by Landlord of rents with knowledge of 
breach by Tenant of any term, agreement, covenant, condition or obligation of 
this Lease shall not be deemed a waiver of such breach.

     (c)    no payment by Tenant or receipt by Landlord of a lesser amount that 
the correct Fixed Rent or additional rent due hereunder shall be deemed to be 
other than a payment on account, nor shall any endorsement or statement on any 
check or any letter accompanying any check or payment be deemed to affect or 
evidence an accord and satisfaction, and Landlord may accept such check or 
payment without prejudice to Landlord's right to recover the balance or pursue 
any other remedy in this Lease or provided at law.

     (d)    if, in connection with obtaining, continuing or renewing financing
for which the Building, land or a leasehold or any interest therein represents
collateral in whole or in part, a bank, insurance company or other lender shall
request reasonable modifications of this Lease as a condition of such financing,
Tenant will not unreasonably withhold, delay6 or defer its consent thereto,
provided that such modifications do not increase the obligations of Tenant
hereunder or adversely affect to a material degree the Tenant's leasehold
interest hereby created.

     ARTICLE 30 -- CURING TENANT'S DEFAULTS, ADDITIONAL RENT

     30.01  If Tenant shall default in the performance of any of its obligations
under this Lease, Landlord, without thereby waiving such default, may (but shall
not be obligated to) perform the same for the account and at the expense of 
Tenant, without notice, in a case of emergency, and in any other case, only if 
such default continues after the expiration of twenty (20) days from the date 
Landlord gives Tenant notice of intention so to do.

     30.02  Bills for any expenses incurred by Landlord in connection with any 
such performance by it for the account of Tenant, and bills for all costs, 
expenses and disbursements of every kind and nature whatsoever, including 
reasonable counsel fees, involved in collecting or endeavoring to collect the 
fixed rent or additional rent or any part thereof or enforcing or endeavoring to
enforce any rights against Tenant, under or in connection with this Lease, or 
pursuant to law, including any such cost, expense and disbursement involved in 
instituting and prosecuting summary proceedings involved in instituting and 
prosecuting summary proceedings, as well as bills for any property, material, 
labor or services provided, furnished, or rendered, by Landlord may be sent by 
Landlord to Tenant monthly, or presented immediately, at Landlord's option, and,
shall be due and payable in accordance with the terms of such bills but not less
than thirty (30) days of receipt thereof.



                                     -43-

<PAGE>
 
            ARTICLE 31 -- NOTICES -- SERVICE OF PROCESS

     31.01  Any notice, statement, demand, request or other communication 
required or permitted pursuant to this Lease or otherwise shall be in writing 
and shall be deemed to have been properly given if sent by registered or 
certified mail, return receipt requested, postage prepaid, addressed to the 
other party at the address hereinabove set forth (except that after the 
Commencement Date, Tenant's address, unless Tenant shall give notice to the 
contrary, shall be the Building), and shall be deemed to have been given on the 
expiration of five (5) business days after mailing. Either party may, by notice 
as aforesaid, designate a different address or addresses for notices, 
statements, demands or other communications intended for it. However, notices 
requesting after hours service pursuant to Sections 8.01 and 9.01 may be given, 
provided they are in writing, by delivery to the Building Superintendent or any 
other person in the Building designated by Landlord to receive such notices, and
notice of fire, accident or other emergency shall be given by telegram or by 
personal delivery of written notice to that address designated for this purpose 
from time to time by the respective parties hereto.

     31.02  Whenever either party shall consist of more than one person or 
entity, any notice, statement, demand, or other communication required or 
permitted, or any payment to be made shall be deemed duly given or paid if 
addressed to or by (or in the case of payment by check, to the order of) any 
such persons or entities who shall be designated from time to time as the 
authorized representative of such party. Such party shall promptly notify the 
other of the identify of such person or entity who is so to act on behalf of 
all persons and entities then comprising such party and of all changes in such 
identify.

     31.03  Tenant agrees to give any Mortgagee who has given a Non-Disturbance 
Agreement, by Certified Mail, a copy of any Notice of Default served upon the 
Landlord by Tenant provided that prior to such notice Tenant has been notified, 
in writing, (by way of Notice of Assignment of Rents and Leases, or otherwise) 
of the address of such Mortgages. Tenant further agrees that if Landlord shall 
have failed to cure such default within the time provided for in this Lease, 
then the Mortgagee shall have an additional thirty (30) days within which to 
cure such default or if such default cannot be cured within that time, then such
additional time as may be necessary if within such thirty (30) days, any 
Mortgagee has commenced and is diligently pursuing the remedies necessary to 
cure such default, (including but not limited to commencement of foreclosure 
proceedings, if necessary to effect such cure) in which event this lease  shall 
not be terminated while such remedies are being so diligently pursued.

          ARTICLE 32 -- ESTOPPEL CERTIFICATE, MEMORANDUM

     32.01  The parties agree, at any time and from time to time, as requested 
by a party, upon not less than ten (10) days' prior notice, to execute and 
deliver without cost or expense to the requesting party a statement certifying 
that this Lease is unmodified and in full force and effect (or if there have 
been modifications, that the same is in full force and effect except as modified
and stating the modifications), certifying the dates to which the Fixed Rent and
additional rent have been paid, and stating whether or not, to the best 
knowledge of the requested party, the  requesting party is in default in 
performance of any of its obligations under this Lease, and, if so, specifying 
each such default of which the requested party may have knowledge, it being


                                     -44-

<PAGE>
 
intended that any such statement delivered pursuant thereto may be relied upon 
by any other person with whom the Landlord may be dealing. The foregoing 
obligation shall be deemed a substantial obligation of the tenancy, the breach 
of which shall give Landlord those remedies herein provided for an event of 
default.

     32.02  Tenant agrees not to record this Lease. At the request of either
party, Landlord and Tenant shall promptly execute, acknowledge and deliver a
memorandum with respect to this Lease sufficient for recording which Tenant may
record. Such memorandum shall not in any circumstances be deemed to change or
otherwise affect any of the obligations or provision of this Lease.

                    ARTICLE 33 -- NO OTHER REPRESENTATIONS,
                          CONSTRUCTION, GOVERNING LAW


     33.01  Tenant expressly acknowledges and agrees that Landlord has not made 
and is not making, and Tenant, in executing and delivering this Lease, is not 
relying upon any warranties, representations, promises or statements, except to 
the extent that the same are expressly set forth in this Lease or in any other 
written agreement which may be made and executed between the parties 
concurrently with the execution and delivery of this Lease and shall expressly 
refer to this Lease. This Lease and said other written agreement(s) made 
concurrently herewith are hereinafter referred to as the "lease documents". It 
is understood and agreed that all understandings and agreements heretofore had 
between the parties are merged in the Lease documents, which alone fully and 
completely express their agreements and that the same are entered into after 
full investigation, neither party relying upon any statement or representation 
not embodied in the Lease documents, made by the other.

     33.02   If any of the provisions of this Lease, or the application thereof
to any person or circumstances shall, to any extent, be invalid or
unenforceable, the remainder of this Lease, or the application of such provision
or provisions to persons or circumstances other than those as to whom or which
it is held invalid or unenforceable, shall not be affected thereby, and every
provision of this Lease shall be valid and enforceable to the fullest extent
permitted by law.

     33.03   This Lease shall be governed in all respects by the laws of the 
State of New Jersey.

                          ARTICLE 34 -- PARTIES BOUND
     
     34.01   The obligations of this Lease shall bind and benefit the successors
and assigns of the parties with the same effect as if mentioned in each instance
where a party is named or referred to, except that no violation of the
provisions of Article 18 shall operate to vest any rights in any successor or
assignee of Tenant, and the provisions of this Article shall not be construed as
modifying the conditions of limitation contained in Article 25. However, the
obligations of Landlord under this Lease shall not be binding upon Landlord
herein named with respect to any period subsequent to the transfer of its
interest in the Building as owner or lessee thereof and in the event of such
transfer said obligation shall thereafter be binding upon each transfer of the
interest of the Landlord herein named as such owner or lessee of the Building,
but only with respect to the period ending with a subsequent transfer within the
meaning of this Article and such transferee, by accepting such interest shall be
deemed to have assumed such
                                    - 45 -
       
<PAGE>
 
obligations except only as may be expressly otherwise provided elsewhere in this
Lease. A lease of Landlord's entire interest in the Building as owner or lessee 
thereof shall be deemed a transfer wherein the meaning of this Article 34.


           ARTICLE 35 -- SHORING AND NOTICE OF ACCIDENTS AND DAMAGE

     35.01  If an excavation or other substructure work shall be undertaken or
authorized upon land adjacent to the Building, Tenant, without liability on the
part of Landlord therefor, shall afford to the person causing or authorized to
cause such excavation or other substructure work, license to enter upon the
Demised Premises for the purpose of doing such work as such person shall deem
necessary to protect or preserve any of the walls or structures of the Building
or surrounding lands from injury or damage and to support the same by proper
foundations, pinning and/or underpinning, and, except in case of emergency, if
so requested by Tenant such entry shall be accomplished in the presence of a
representative of Tenant, who shall be designated by Tenant promptly upon
Landlord's request. The said license to enter shall be afforded by Tenant
without any claim for damages or indemnity against Landlord and Tenant shall not
be entitled to any diminution or abatement of rent on account thereof.

     35.02  Tenant shall give notice to Landlord, promptly after Tenant learns 
thereof, of (i) any accident in or about the Demised Premises or the Building,
(ii) all fires in the Demised Premises, (iii) all damages to or defects in the
Demised Premises, including the fixtures, equipment and appurtenances thereto,
for the repair of which Landlord might be responsible or which constitutes
Landlord's property, and (iv) all damage to or defects in any parts or
appurtenances to the Building's sanitary, electrical, heating, ventilating, air
conditioning, elevator and other systems located in or passing through the
Demised Premises, provided that the Landlord shall be reasonably diligent with
respect thereto and shall perform such work, except in case of emergency, at
times reasonably convenient to Tenant and otherwise in such manner and to the
extent practical as will not unreasonably interfere with Tenant's use and
occupancy of the Demised Premises.

                    ARTICLE 36 -- VAULT, VAULT SPACE, AREA

     No vaults, vault space or area whether or not enclosed or covered not
within the property line of the Building is leased hereunder, anything contained
in or indicated on any sketch, blue print or plan or anything contained
elsewhere in this Lease to the contrary notwithstanding. Landlord makes no
representation as to the location of the property line of the Building. All
vaults and vault space and all such areas not within the property line of the
Building, which Tenant may be permitted to use and/or occupy, is to be used
and/or occupied under a revocable license, and if any such license be revoked,
or if the amount of such space or area be diminished or required by any federal,
state or municipal authority or public utility, Landlord shall not be subject to
any liability nor shall Tenant be entitled to any compensation or diminution or
abatement of rent nor shall such revocation diminution or requisition be deemed
constructive or actual eviction. Any tax fee or charge of municipal authorities
for such vault or area shall be paid by Tenant.

                                     -46-
<PAGE>
 
                      ARTICLE 37 -- INABILITY TO PERFORM

     This Lease and the obligation of Tenant to pay rent hereunder and perform 
all of the other covenants and agreements hereunder on part of Tenant to be 
performed shall in no wise be affected, impaired or excused because Landlord is 
unable to fulfill any of its obligations under this lease or to supply or is 
delayed in supplying any service expressly or impliedly to be supplied or is 
unable to make, or is delayed in making any repair, additions, alterations or 
decorations or is unable to supply or is delayed in supplying any equipment or 
fixtures if Landlord is prevented or delayed from so doing by reason of strike 
or labor troubles or any cause whatsoever including but not limited to, 
government preemption in connection with a National Emergency or by reason of 
any rule, order of regulation of any department or subdivision thereof of any 
government agency or by reason of the conditions of supply and demand which have
been or are affected by war or other emergency.

                      ARTICLE 38-- LIABILITY OF LANDLORD

     Tenant shall look solely to the estate and interest of Landlord, its 
successors and assigns, in the land and Building for the collection of a 
judgement (or other judicial process) requiring the payment of money by Landlord
in the event of any default by Landlord hereunder, and no other property or 
assets of Landlord shall be subject to levy, execution or other enforcement 
procedure for the satisfaction of Tenant's remedies under or with respect to 
either this Lease, the relationship of Landlord and Tenant hereunder or Tenant's
use and occupancy of the Demised Premises. Neither the partners comprising 
Landlord (the "Partners"), nor the partners, shareholders, directors and 
officers of Landlord or the Partners shall be liable for the performance of 
Landlord's obligations under this Lease.

                            ARTICLE 39 -- BROKERAGE

     Tenant represents and warrant that it has dealt only with Dolan Realty, 
Inc. and Grubb & Ellis in connection with this Lease and Tenant does hereby 
agree to indemnify and hold harmless the Landlord of and from any and all loss, 
costs, damage or expense (including, without limitation, attorneys' fees and 
disbursements) incurred by the Landlord by reason of any claim of or liability 
to any other broker who shall claim to have dealt with Landlord or Tenant in 
connection with this Lease.

                      ARTICLE 40 -- FIRST RENEWAL OPTION

     40.01  If Tenant shall not be in default under any term, covenant and 
condition of this Lease on the part of Tenant to be performed beyond any 
applicable grace period after notice, Tenant may by notice in writing given to 
Landlord at least six (6) months before the Expiration Date (the "First Option 
Exercise Date") renew and extend this Lease for the further term of five (5) 
years (the "First Renewal Option Term") for the entire Demised Premises at 
Tenant's option according to the terms and conditions of this Lease, as amended 
hereunder, with Fixed Rent at the fair market Fixed Rent for the Demised 
Premises at the beginning of the First Renewal Option Term, plus additional rent
as provided in this Lease for the Demised Premises.

                                     -47-
<PAGE>
 
     40.02  If Tenant elects to exercise its option hereunder, the Term shall be
extended for the Demised Premises without execution of an extension or renewal 
lease. Within ten (10) days after a request of either party after the exercise 
of such option, Landlord and Tenant shall execute, acknowledge and deliver to 
each other duplicate originals of any instrument confirming that such option was
effectively exercised, but Tenant may not record such instrument.

     40.03  At least four (4) months prior to the First Option Exercise Date, 
the parties shall meet and seek to determine fair market Fixed Rent by mutual 
agreement. If the parties are unable to agree on the fair market Fixed Rent 
three (3) months before the First Option Exercise Date, the parties shall, 
within ten (10) days thereafter, choose a licensed real estate appraiser who 
shall have twenty (20) days to determine the fair market Fixed Rent. The cost of
said real estate appraiser shall be borne equally by the parties. If the parties
are unable to agree on a licensed real estate appraiser within such ten (10) day
period, each party shall, within five (5) days thereafter, select an appraiser 
who shall have twenty (20) days after selection to determine the fair market 
Fixed Rent. If the difference between the two appraisals is five (5%) percent or
less of the lower appraisal, then the fair market Fixed Rent which shall be 
binding on the parties shall be the average of the two appraisals. If the 
difference between the two appraisals is greater than five (5%) percent of the 
lower appraisal, the two appraisers shall, within five (5) days after completion
of the appraisals, select a third licensed real estate appraiser who shall, 
within twenty (20) days of selection, determine fair market Fixed Rent. In such 
case, the fair market Fixed Rent binding on the parties shall be either (i) the 
fair market Fixed Rent determined by the third appraiser, if his appraisal is 
higher than one of the other appraisals and lower than the other, or (ii) in any
other case, the fair market Fixed Rent determined by one of the other appraisers
which is closer to the fair market Fixed Rent determined by the third appraiser.
The cost of the third appraisal shall be borne equally by the parties.

                      ARTICLE 41 -- SECOND RENEWAL OPTION

     41.01  If Tenant elected to exercise the First Renewal Option and shall not
be in default under any term, covenant and condition of this Lease on the part 
of Tenant to be performed beyond any applicable grace period after notice, 
Tenant may by notice in writing given to Landlord at least six (6) months before
the Expiration Date of the First Renewal Option (the "Second Option Exercise 
Date") renew and extend this Lease for the further term of five (5) years (the  
"Second Renewal Option Term") for the entire Demised Premises at Tenant's option
according to the terms and conditions of this Lease, as amended hereunder, with 
Fixed Rent at the fair market. Fixed Rent for the Demised Premises at the 
beginning of the Second Renewal Option Term, plus additional rent as provided in
this Lease for the Demised Premises.

     41.02  If Tenant elects to exercise its option hereunder, the Term shall 
be extended for the Demised Premises without execution of an extension or 
renewal lease. Within ten (10) days after a request of either party after the 
exercise of such option, Landlord and Tenant shall execute, acknowledge and 
deliver to each other duplicate originals of any instrument confirming that such
option was effectively exercised, but Tenant may not record such instrument.

                                     -48-
<PAGE>
 
     41.03  At least four (4) months prior to the Second Option Exercise Date,
the parties shall meet and seek to determine fair market Fixed Rent by mutual
agreement. If the parties are unable to agree on the fair market Fixed Rent
three (3) months before the Second Option Exercise Date, the parties shall,
within ten (10) days thereafter, choose a licensed real estate appraiser who
shall have twenty (20) days to determine the fair market Fixed Rent. The cost of
said real estate appraiser shall be borne equally by the parties. If the parties
are unable to agree on a licensed real estate appraiser within such ten (10) day
period, each party shall, within five (5) days thereafter, select an appraiser
who shall have twenty (20) days after selection to determine the fair market
Fixed Rent. If the difference between the two appraisals is five (5%) percent or
less of the lower appraisal, then the fair market Fixed Rent which shall be
binding on the parties shall be the average of the two appraisals. If the
difference between the two appraisals is greater than five (5%) percent of the
lower appraisal, the two appraisers shall, within five (5) days after completion
of the appraisals, select a third licensed real estate appraiser who shall,
within twenty (20) days of selection, determine fair market Fixed Rent. In such
case, the fair market Fixed Rent binding on the parties shall be either (i) the
fair market Fixed Rent determined by the third appraiser, if his appraisal is
higher than one of the other appraisals and lower than the other, or (ii) in any
other case, the fair market Fixed Rent determined by one of the other appraisers
which is closer to the fair market Fixed Rent determined by the third appraiser.
The cost of the third appraisal shall be borne equally by the parties.

                    ARTICLE 42 -- MISCELLANEOUS PROVISIONS

     42.01  All work, including but not limited to, waxing or additional
cleaning that Tenant does or shall do in the Demised Premises, shall be done by
contractors employing union labor, approved in writing by Landlord and shall at
all times conform to the standards of the Building and shall comply with all
laws and/or requirements of public authorities. Tenant, as additional rent,
shall indemnify and hold harmless Landlord against any loss or damage Landlord
may sustain by reason of, and against, any order, decrees, judgments, attorney's
fees and expenses resulting from, failure of Tenant to comply with the
provisions hereof.

     42.02  The Article headings in this Lease and the Table of Contents 
prefixed to this Lease are inserted only as a matter of convenience or 
reference, and are not to be given any effect whatsoever in construing this 
Lease.

                                     -49-
<PAGE>
 
    IN WITNESS WHEREOF, the parties hereto have executed this instrument the day
and year first above written.

                                   LANDLORD:
                                        EVERGREEN AMERICA CORPORATION


                                        By: /s/ Howard Tung
                                           -------------------------------------
                                           HOWARD TUNG, Deputy Junior
                                           Vice President

/s/ Tony Wang
- ---------------------------------
TONY WANG
Witness for Landlord

                                   TENANT:
                                        FOCAL COMMUNICATIONS CORPORATION
                                        OF NEW JERSEY, A DELAWARE
                                        CORPORATION


                                        By: /s/ John R. Burnicle
                                           -------------------------------------


                                        Its:         C.O.O.
                                            ------------------------------------
                                            (Title)

/s/ [SIGNATURE ILLEGIBLE]^^
- ---------------------------------

Witness for Tenant

                                      -50-
<PAGE>
 
                                  EXHIBIT A-1
                                  -----------

                               DEMISED PREMISES




                           [FLOOR PLAN APPEARS HERE]

                                      -51-
<PAGE>
 
                                  EXHIBIT A-2
                                  -----------

                      EMERGENCY STAND-BY GENERATOR SPACE

                                      -52-
<PAGE>
 
                                  EXHIBIT A-3
                                  -----------

                                  ROOF SPACE

                                      -53-
<PAGE>
 
                      EXHIBIT B -- RULES AND REGULATIONS

     1)   The sidewalks, entrances, passages, lobby, elevators, vestibules,
stairways, corridors or halls shall not be obstructed or encumbered by any
tenant or used for any purpose other than ingress and egress to and from the
Demised Premises and Tenant shall not permit any of its employees, agents or
invitees to congregate in any of said areas. No door mat of any kind whatsoever
shall be placed or left in any public hall or outside any entry door of the
Demised Premises.

     2)   No awnings or other projections shall be attached to the outside walls
of the Building.  No curtains, blinds, shades or screens shall be attached to or
hung in, or used in connection with, any window or door of the Demised Premises,
without the prior written consent of Landlord.  Such curtains, blinds, shades or
screens must be of a quality, type, design and color, and attached in the
manner, approved by Landlord.

     3)   No sign, insignia, advertisements, object, notice or other lettering
shall be exhibited, inscribed, painted or affixed by any tenant on any part of
the outside or inside of the Demised Premises or the Building without the prior
written consent of Landlord.  In the event of the violation of the foregoing by
any tenant, Landlord may remove the same without any liability, and may charge
the expense incurred in such removal to the tenant or tenants violating this
rule.  Interior signs and lettering on doors and the directory shall, if and
when approved by Landlord, be inscribed, painted or affixed for each tenant by
Landlord at the expense of such tenant, and shall be of a size, color and style
acceptable to Landlord.

     4)   The sashes, sash doors, skylights, windows and doors that reflect or
admit light and air into the halls, passageways or other public places in the
Building shall not be covered or obstructed by Tenant, nor shall any bottles,
parcels or other articles be placed on the window sills.

     5)   No showcases or other articles shall be put in front of or affixed to
any part of the exteriors of the Building, nor placed in the halls, corridors or
vestibules.

     6)   The water and wash closets and other plumbing fixtures shall not be
used for any purposes other than those for which they were designed or
constructed, and no sweepings, rubbish, rags, acids or other substances shall be
thrown or deposited therein. All damages resulting from any misuse of the
fixtures shall be borne by the tenant who, or whose servants, employees, agents,
visitors or licensees shall have caused the same.

     7)   No tenant shall mark, paint, drill into or in any way deface any part
of the Demised Premises or the Building. No boring, cutting or stringing of
wires shall be permitted, except with the prior written consent of Landlord, and
as Landlord may direct. No tenant shall lay linoleum or other similar floor
covering, so that the same shall come in direct contact with the floor of the
Demised Premises, and, if linoleum or other similar floor covering is desired to
be used an interlining of builders deadening felt shall be first affixed to the
floor, by a paste or other material, soluble in water, the use of cement and
other similar adhesive material being expressly prohibited.

     8)   No bicycles, vehicles, animals, fish or birds of any kind shall be
brought into or kept in or about the premises.

                                      -54-
<PAGE>
 
     9)   No noise, including, but not limited to, music or the playing of
musical instruments, recordings, radio or television which, in the judgment of
Landlord, might disturb other tenants in the Building, shall be made or
permitted by any tenant. Nothing shall be done or permitted in the Demised
Premises by Tenant which would impair or interfere with the use or enjoyment by
any other tenant of any other space in the Building. No tenant shall throw
anything out of the doors, windows or skylights or down the passageways.

     10)  Tenant, its servants, employees, agents, visitors or licensees, shall
at no time bring or keep upon the Demised Premises any explosive fluid, chemical
or substance, nor any inflammable or combustible objects or materials except
subject to the provisions of Section 21.02(a) of the foregoing Lease.

     11)  Additional locks or bolts of any kind which shall not be operable by
the Grand Master Key for the Building shall not be placed upon any of the doors
or windows by any tenant, nor shall any changes be made in locks or the
mechanism thereof which shall make such locks inoperable by said Grand Master
Key.  Each tenant shall, upon the termination of its tenancy, turn over to
Landlord all keys of offices and toilet rooms, either furnished to, or otherwise
procured by, such tenant and in the event of the loss of any keys furnished by
Landlord, such tenant shall pay to Landlord the cost thereof.

     12)  All removals from the Demised Premises or the Building, or the moving
or carrying in or out of the Demised Premises or the Building of any safes,
freight, furniture, packages, boxes, crates or any other object or matter of any
description must take place during such hours and using such elevators as
Landlord or its agent may determine from time to time.  All deliveries of any
nature whatsoever to the Building or the Demised Premises must be made only
through Building entrances specified by Landlord for such deliveries.  Landlord
reserves the right to inspect all objects and matter to be brought into the
Building and to exclude from the Building all objects and matter which violate
any of these Rules and Regulations or the Lease of which these Rules and
Regulations are a part.  Landlord may require any person leaving the Building
with any package or other object or matter, to submit a pass, listing such
package or object or matter from the tenant from whose premises the package or
other object or matter is being removed, but the establishment and enforcement
of such requirement shall not impose any responsibility on the Landlord for the
protection of any tenant against the removal of property from the premises of
such tenant.  Landlord shall, in no way, be liable to Tenant for damages or loss
arising from the admission, exclusion or ejection of any person to or from the
Demised Premises or the Building under the provisions of this Rule 12 or Rule 16
hereof.

     13)  Tenant shall not occupy or permit any portion of the Demised Premises
to be occupied as an office for a public stenographer or public typist, or for
the possession, storage, manufacture, or sale of beer, wine or liquor,
narcotics, dope, tobacco in any form, or as a barber, beauty or manicure shop,
or as an employment bureau.  Tenant shall not engage or pay any employees on the
Demised Premises, except those actually working for Tenant on the Demised
Premises, nor advertise for laborers giving an address at the Demised Premises.
Tenant shall not use the Demised Premises or any part thereof, or permit the
Demised Premises or any part thereof to be used, for manufacturing, or for sale
at auction of merchandise, goods or property of any kind.

                                      -55-
<PAGE>
 
     14)  Tenant shall not obtain, purchase or accept for use in the Demised
Premises ice, drinking water, food, beverage, towel, barbering, boot blacking,
cleaning, floor polishing or other similar services from any persons not
authorized by Landlord in writing to furnish such services, provided always that
the charges for such services by persons authorized by Landlord are not
excessive.  Such services shall be furnished only at such hours, in such places
within the Demised Premises, and under such regulations as may be fixed by
Landlord.  Tenant shall not purchase or contract for waxing, rug shampooing,
venetian blind washing, furniture polishing, lamp servicing, cleaning of
electric fixtures, removal of garbage or towel service in the Demised Premises
except from contractors, companies or persons approved by the Landlord.

     15)  Landlord shall have the right to prohibit any advertising or
identifying sign by any tenant which in Landlord's judgment tends to impair the
reputation of the Building or its desirability as a Building for offices, and
upon written notice from Landlord, such tenant shall refrain from or discontinue
such advertising or identifying sign.

     16)  Landlord reserves the right to exclude from the Building during hours
other than Regular Business Hours (as defined in the foregoing Lease) all
persons who do not present a pass to the Building signed by Landlord.  All
persons entering and/or leaving the Building during hours other than Regular
Business Hours may be required to sign a register.  Landlord will furnish passes
to persons for whom any tenant requests such pass and shall be liable to
Landlord for all acts or omissions of such persons.

     17)  Tenant, before closing and leaving the Demised Premises at any time,
shall see that all lights are turned out.  All entrance doors in the Demised
Premises shall be left locked by Tenant when the Demised Premises are not in
use.  Entrance doors shall not be left open at any time.

     18)  Tenant shall, at Tenant's expense, provide artificial light and
electrical energy for the employees of Landlord and/or Landlord's contractors
while doing janitor service or other cleaning in the Demised Premises and while
making repairs or alterations in the Demised Premises.

     19)  The Demised Premises shall not be used for lodging or sleeping or for
any immoral or illegal purpose.

     20)  The requirements of tenants will be attended to only upon application
at the office of the Building.  Employees of Landlord shall not perform any work
or do anything outside of their regular duties, unless under special
instructions from Landlord.

     21)  Canvassing, soliciting and peddling in the Building are prohibited and
each tenant shall cooperate to prevent the same.

     22)  There shall not be used in any space, or in any lobbies, corridors,
public halls or other public areas of the Building, either by any tenant or by
jobbers or any others, in the moving or delivery or receipt of safes, freight,
furniture, packages, boxes, crates, paper, office material, or any other object
or thing, any hand trucks except those equipped with rubber tires, side guards,
and such other safeguards as Landlord shall require.  No move or delivery of any
object or thing of whatever nature, other than light-weight objects hand-carried
by not more than one person, shall be made without at least 24 hours' prior
written notice by Tenant to Landlord and without Tenant, prior to any such move
or delivery, laying (without affixation or attachment to any part of 

                                      -56-
<PAGE>
 
the floor or floor covering) adequate masonite or plywood sheets covering all
lobby, corridor, public hall and other public area floors of the Building
(whether carpeted or terrazzo) over which such move or delivery shall take
place.

     23)  Tenant shall not cause or permit any odors of cooking or other
processes or any unusual or objectionable odors to emanate from the Demised
Premises which would annoy other tenants or create a public or private nuisance.
No cooking shall be done in the Demised Premises except as is expressly
permitted in the foregoing Lease.

     24)  Tenant shall cooperate with Landlord in obtaining maximum
effectiveness of the cooling system by lowering and closing venetian blinds
and/or drapes and curtains when the sun's ray fall directly on the windows of
the Demised Premises. Tenant shall not permit the heating, air-conditioning and
ventilation system to become blocked by Tenant's curtains, drapes or other
installations.

     25)  Landlord reserves the right to rescind, alter or waive any rule or
regulation at any time prescribed for the Building when, in its judgment, if
deems it necessary or desirable for the reputation, safety, care or appearance
of the Building, or the preservation of good order therein, or the operation or
maintenance of the Building or the equipment thereof, or the comfort of tenants
or others in the Building.  No rescission, alteration or waiver of any rule or
regulation in favor of one tenant shall operate as a rescission, alteration or
waiver in favor of any other tenant.

     26)  Tenant shall not permit its personnel, agents or visitors to litter
any public areas of the Building or the land or improvements on the land on
which the Building is located (including, without limitation, the walkways and
parking areas located thereon), and Tenant shall be responsible to, and shall
pay Landlord for the cost of removal of such litter within ten (10) days of
notice thereof by Landlord.

     27)  Subject to the provisions of Paragraph 10.01(c) Landlord shall not
unreasonably withhold its consent to the installation, maintenance and operation
by Tenant in the Demised Premises of office duplicating machines, teletype
machines and other business machines and machinery customarily used in offices
in the ordinary course of business, provided, however, that Tenant shall comply
with all other obligations of this Lease that are applicable to or result from
such installation, or operation.

     28)  Landlord shall not unreasonably withhold from Tenant any approval
provided for in the Rules and Regulations.

     29)  Any moving of furniture or equipment into or out of the Demised
Premises must be done by Tenant at its own cost and expense, on Monday through
Friday after 6:00 p.m., or on Saturday, subject however, to the prior written
consent of Landlord.  If such move requires use of an elevator, such move shall
not be in excess of such elevator's load capacity.

                                      -57-
<PAGE>
 
                                   EXHIBIT C
                                   ---------

                                 TENANT'S WORK

                                      -58-
<PAGE>
 
                       EXHIBIT C-1 -- BUILDING RULES AND
                 REGULATIONS FOR TRADES CONDUCTING OPERATIONS
                                IN THE BUILDING


1.   All plans and specifications for any proposed Tenant Work must be submitted
     to the Building office for approval by the Landlord, which approval shall
     not be unreasonably withheld or delayed.

2.   Prior to the commencement of any work, all contractors must have a current
     insurance certificate on file in the Building office. (See attached
     insurance requirements for trades conducting operations at One Evertrust
     Plaza.)

3.   All work is to be performed in a safe and lawful manner, using contractors
     approved by the Landlord, which consent shall not be unreasonably withheld.
     All work must comply with applicable laws and all requirements and
     regulations of Municipal and other governmental or duly constituted bodies
     exercising authority, and this compliance shall include the filing of plans
     and other documents as required, and the procuring of any required licenses
     or permits prior to commencement of any work. Tenant shall submit the
     following certificates to Landlord upon completion of the work:

     A.   Approvals issued by the building department.

     B.   Certificate of Occupancy.

     C.   Air Balance Report.

4.   Any work which will require an electrical shutdown or drain down of the
     Building's chilled water, condenser water, or domestic water systems must
     be performed after 6:00 PM or on the weekends. A written request for this
     work to be performed must be received by the Building office at least five
     (5) business days prior to the commencement of this work. In addition to
     the above, this work must be supervised by a Building engineer, and the
     contractor must agree to pay the cost of employing the Building engineer on
     overtime at an hourly rate of $55.00 per man hour.

5.   No workers are permitted to make use of passenger elevators while
     transporting tools or materials of any kind. Gang boxes or hand trucks are
     not permitted on passenger elevators under any circumstances.

6.   For the duration of the work, the contractor must provide masonite
     protection for all walls and floors throughout all common areas which lead
     to the contractors area of work. Any damage to these walls and floors
     caused by the contractor is to be repaired immediately with no cost to the
     Landlord.

7.   Tenant's workmen and mechanics must work in harmony, and not interfere with
     any labor employed by the Landlord, Landlord's mechanics or contractors or
     by and other tenant or its contractors.

8.   All contractors shall comply with the rules of the Building as to the hours
     of availability of the Building elevators and the manner of handling
     materials, equipment, and debris to avoid conflict and interference with
     Building operation. Deliveries are not permitted between the following
     periods: 8 AM - 10 AM, 11:30 AM - 1 PM, 4 PM - 6 PM.

                                      -59-
<PAGE>
 
9.   Contractor shall be required to pay for the use of service elevators after
     business hours at Landlord's standard rate of $80.00 per hour.

10.  Demolition must be performed after 6:00 PM or on weekends. The delivery of
     materials, equipment, and removal of debris must be arranged to avoid any
     inconvenience and annoyance to other tenants. Cleaning must be controlled
     to prevent dirt and dust from infiltrating into adjacent tenant or
     mechanical areas.

11.  Contractor shall make available fire extinguishers based on the following: 

     Alterations up to 5,000 sq. ft. - one (1) fire extinguisher

     Alterations over 5,000 sq. ft. - one (1) fire extinguisher for every
     additional 5,000 sq. ft. thereover. Said fire extinguisher shall be 25 lb.
     type approved for type A, B, C, fires and shall be kept and maintained on
     the premises by Tenant's contractor for the duration of the work.

12.  Contractor shall be required to pay for the temporary use of electricity
     and water at the Landlord's standard rate of $15.00 per day.

13.  Landlord reserves the right to stop all work in the event of the breach of
     any of the terms or conditions listed above.

                                      -60-
<PAGE>
 
               EXHIBIT C-2 -- INSURANCE REQUIREMENTS FOR TRADES
                     CONDUCTING OPERATIONS IN THE BUILDING


1.  The Contractor will, throughout the duration of any contract or any work
    authorized under purchase order, at its expense, carry and from time to time
    renew, Workman's Compensation Insurance, Public Liability Insurance in the
    amount of $1,000,000 single limit covering both Bodily Injury and Property
    Damage including coverage for below noted indemnity agreement in such
    companies as may be approved by the Landlord which approval shall not be
    unreasonably withheld or delayed.  Certificates in the customary form,
    evidencing that premiums therefore have been paid, shall be delivered to the
    Landlord simultaneously with the execution of any contract and prior to
    performing any work authorized under a purchase order or contract, and
    within fifteen (15) days prior to expiration of such insurance like
    certificates shall be delivered to the Landlord evidencing the renewal of
    such insurance, together with evidence satisfactory to the Landlord of the
    payment of the premium.  All certificates must obtain a definite provision
                                                            ------------------
    that if such policies are cancelled or changed during the periods of
    coverage as stated therein, in such a manner as to affect this certificate,
    written notice will be mailed to the Landlord by registered mail ten (10)
    days prior to such cancellation or change.

2.  Provision must also be made as provided above to insure the Hold Harmless
    Agreement which reads as follows:

       "The Contractor hereby agrees to indemnify and save Harmless
       the Evergreen America Corporation and any of its subsidiaries
       from and against all liability claims and demands on account of
       injury to persons including death resulting therefrom and
       damage to property arising out of the performance of this
       contract by the Contractor, employees and agents of the
       Contractor and Contractor's property, except from and against
       such claims and demands which may arise out of the sole
       negligence of the owner, Evergreen America Corporation or any
       of its subsidiaries. The Contractor will at his or its own
       expense, defend any and all actions at law brought against the
       owner and/or the agent based thereon and shall pay all attorney
       fees and all other expenses, and promptly discharge any
       judgments arising therefrom. These conditions shall also apply
       to any subcontracted operations."

                                      -61-
<PAGE>
 
                        EXHIBIT D -- CLEANING STANDARDS

 I.    Plaza and Lobby Levels - Nightly
       --------------------------------

       The entrance lobbies are to be kept neat and clean at all times and the
       following minimum cleaning operations shall be maintained to attain this
       effect:

       a.  Sweep with chemically treated dust mop all granite floors, damp mop
           any spillage.

       b.  Wash and spray buff lobby floors nightly.

       c.  Damp wipe all cigarette urns and replace sand or water as necessary.

       d.  Damp wipe and dry the Reception Console Center.

       e.  Damp wipe Directory board plastic with a destatisizer.

       f.  Damp wipe and dry ledges of flower planters.

       g.  Damp wipe and dry all elevator starter panels.

       h.  Wash all metal doors, hand rails and all revolving doors and drums of
           revolving doors, interior and exterior.

       i.  Vacuum all carpeting.

       j.  Remove any graffiti or obscenities on metal or panels.

       k.  Remove gum from carpeting.

       l.  Vacuum floor saddles.

       m.  Dust mail depository and damp wipe fingerprints.

       n.  Dust walls and wash if soiled.

       o.  Wash all glass walls and doors.

       p.  Wash all rubber mats and/or vacuum carpet runners.

       Plaza/Lobby Areas - Periodic
       ----------------------------

       q.  High dust all ornamental decorations two times a year.

       r.  High dust and wash all electrical and air-conditioning diffusers two
           times a year.

 II.   Elevators
       ---------

       a.  Vacuum rugs of all elevators nightly and remove gum marks; wash, wax
           and polish if tiled.

       b.  Wipe down panels of elevator cabs nightly and remove any graffiti or
           obscenities.  Polish same weekly.

       c.  Wipe down all metal in cabs, indicators and elevator doors nightly
           using an approved cleaner.

       d.  Vacuum clean lobby elevator saddles and tracks nightly.

       e.  Wash and polish door saddles and frames on floors above lobby twice
           per month and vacuum tracks.

                                      -62-
<PAGE>
 
       f.  Remove foreign matter from top of light fixtures in elevator cabs
           nightly.

       g.  Vacuum tracks and wipe clean nightly.

III.   General Office Areas - Nightly
       ------------------------------

       a.  Sweep all hardsurfaced flooring using approved dustdown preparation
           and damp mop weekly marble terrazzo, wood or other untreated
           flooring.

       b.  Vacuum sweep all carpets and rugs, moving only light furniture
           (desks, file cabinets, etc. not to be moved.)

       c.  Hand dust and wipe clean with damp or chemically treated cloth all
           furniture, file cabinets, fixtures, window sills, and wash said sills
           and tops if necessary.

       d.  Dust and wipe clean all telephones.

       e.  Dust all chair rails, trim, etc.

       f.  Remove all gum and foreign matter on sight.  Spot clean floors.

       g.  Empty all waste receptacles and remove wastepaper and waste materials
           to a designated area.

       h.  Damp dust interiors of all waste disposal receptacles as necessary.

       i.  Empty and wipe clean all ashtrays and screen all sand urns; replace
           sand as necessary.

       j.  Wash clean all water fountains and water coolers.

       k.  Dust all glass furniture tops.

       l.  Remove hand marks on elevator hatchway doors.

       m.  Adjust vertical blinds to uniform standard.

       n.  Keep service corridors on each floor in clean and orderly condition.

       o.  Dust all door louvers within reach.

       p.  Remove finger smudges for all metal partitions and surfaces.

 IV.   Periodic
       --------

       a.  Hand dust all ventilating louvers.

       b.  Dust all baseboards once per month, remove stains if possible.

       c.  Dust all lamp shades monthly.

       d.  High dust and wash all electrical and air-conditioning diffusers
           twice a year.

       e.  High dust all ornamental decorations semi-annually.

                                      -63-
<PAGE>
 
       f.  Wash floors in public and private stairwells throughout the Building
           monthly.

       g.  Wash telephones monthly.

       h.  Dust quarterly all picture frames, charts and similar hangings which
           were not reached in nightly cleaning.

       i.  Dust all vertical surfaces such as walls, partitions, doors, window
           frames and other surfaces not reached in nightly cleaning four (4)
           times per year.

       j.  Dust exterior of lighting fixtures twice a year.

       k.  Dust all vertical blinds quarterly.

       l.  Dust quarterly all air-conditioning louvers, grills, etc. not reached
           in nightly cleaning and surrounding areas twice a year.

       m.  Clean all interior window metal and other unpainted interior metal
           surfaces of the Common Area of the perimeter walls once per year
           using a metal cleaning product.

       n.  Strip and polish lobby floors weekly.

       o.  Wash all cigarette urns weekly.

 V.    Lavatories - Nightly
       --------------------

       a.  Wash and disinfect all floors and baseboards.

       b.  Wash all mirrors and powder shelves.

       c.  Wash all bright work.

       d.  Wash all plumbing fixtures.

       e.  Wash and disinfect all toilet seats, both sides.

       f.  Scour, wash and disinfect all basins, toilet bowls and urinals.

       g.  Empty paper towel receptacles and remove paper to designated area.

       h.  Wipe and fill toilet tissue holders.

       i.  Wipe and fill soap, sanitary napkin and paper towel dispensers.

       j.  Empty and clean sanitary disposal receptacles.

       k.  Hand dust and clean all receptacles and dispensers.

       l.  Remove finger marks from painted surfaces.

       m.  Remove all graffiti.

       n.  Dust and clean partitions and walls.

       o.  Wash tile wall surfaces subject to splashing.

                                      -64-
<PAGE>
 
       p.  Report all mechanical deficiencies, i.e., dripping faucets, etc., to
           the Building Manager.

       Periodic
       --------

       a.  Wash all partitions and dispensers once a week.

       b.  Scrub floors as necessary but not less than once a week.

       c.  Hand dust and wash all tile walls once each month, more often if
           necessary.

       d.  High dusting to be done once each month which includes lights, walls,
           and grills; wash such fixtures, including lamps and lenses, twice
           every year.

 VI.   Public Areas
       ------------

       a.  Police all public area and stairwells throughout the entire Building
           and keep in clean condition, sweep daily and mop, as necessary, but
           at least once per month.

       b.  Clean firehoses, extinguishers and similar equipment as necessary but
           at least once per month.

       c.  Dust all ceilings, etc., weekly and high dust quarterly.

VII.   Building Service Areas
       ----------------------

       a.  Hose all ramps, loading dock, trucking areas, garbage storage room,
           etc., daily and scrub and steam clean as necessary, but at least once
           per month.

       b.  Keep loading docks and driveway entrance area, ramps and garage areas
           in a neat, clean condition at all times.  Keep wastepaper, cardboard
           and rubbish, etc., stored in approved receptacles or assigned rooms.
           Keep floors, walls, driveway, walkway and dock area clean of grease,
           oil and other stains.  Maintain an adequate stock of absorbent
           material for oil and grease stains.

       c.  Slop sinks are to be cleaned after use.  Mops, rags and equipment are
           to be cleaned and stored in racks.  Walls and floors are to be kept
           clean at all times.

       d.  Electric and telephone closets and storerooms are to be kept free
           from debris and material.  Floors are to be swept weekly and washed
           monthly.  Report storage of extraneous material and equipment to
           Building Manager.

       e.  Police main Building entrance lobby.

       f.  Police elevator cabs and clean, dust and rubdown walls as necessary.

       g.  Police men's lavatories and fill toilet tissue dispensers.

       h.  Set out rubber mats on rainy days; keep in clean condition.

       i.  Clean all cigarette urns and replace sand as necessary.

       j.  Clean all stairwells and fire tower; dust all handrails, spindles and
           wash stairs as necessary.

                                      -65-
<PAGE>
 
       k.  Sweep and wash lobby and common area floors daily.

       l.  Clean roof setbacks as necessary.

       m.  Keep frames of entrance doors in clean condition.

       n.  Clean standpipes and Siamese sprinkler connections as necessary.

       o.  Exterior metal work, marble, etc. of Building entrances to be kept in
           clean condition at all times.

       p.  Properly maintain exterior of Building at the ground level.

VIII.  Window Cleaning
       ---------------

       a.  Clean all windows on the outside and inside from the ground floor to
           the roof twice a year.  Window frames and associated metal to be
           wiped clean at the same time.

       b.  Partition glass throughout the Building interior in public areas, to
           be cleaned once per month.

       c.  Clean entrance doors two (2) times each day.

       d.  Clean directory glass daily.

       e.  Clean all glass on the first floor daily.

       f.  Clean all glass doors and panels daily.

       g.  Clean all mail chute glass as necessary.

 IX.  Walkways, Plaza
      ---------------

       a.  Police walkways and Plaza area two (2) times daily.

       b.  Remove all gum and foreign matter on sight.

       c.  Clean all Plaza areas, sidewalks and driveways.

 X.  Garage (If Applicable)
     ----------------------

       Police garage daily removing all accumulated debris.

 XI.   Pest Control
       ------------

       To be furnished as required to prevent infestation.

XII.   Duties of Day Matrons
       ---------------------

       a.  Police all ladies lavatories twice each day.

       b.  Fill toilet tissue dispensers with toilet tissue.

       c.  Fill paper towel dispensers with paper towels.

       d.  Fill sanitary napkin dispensers with sanitary napkins.

       e.  Fill soap dispensers with liquid hand soap.

                                      -66-
<PAGE>
 
XIII.  Duties of Day Porters
       ---------------------

       a.  Police Plaza entrance five (5) times a day, five (5) days a week.

       b.  Empty and strain all cigarette urns, three (3) times a day.

       c.  Elevator cab floors are to be vacuumed two (2) times a day - more
           often if necessary.

       d.  Wipe clean and remove finger marks from all metal and bright work
           throughout interior of Plaza and lobby and up to hand reach daily.

       e.  Sweep walkways, Plaza, ramps, loading dock, trucking area, etc. twice
           daily, more often as needed.

       f.  Lay down and remove lobby runners as necessary.

       g.  Police roof setbacks.

       h.  Sweep and dust the trafficked staircases daily.

       i.  Wash trafficked staircases weekly.

       j.  Wash the flooring in the trafficked main engine room, main pump room,
           etc., weekly.

       k.  Police all mens' lavatories two (2) times each day.

       l.  Fill all dispensers in mens' lavatories as required.

       m.  Keep all public telephones and their enclosures in a clean condition.

       n.  Empty waste receptacles on Plaza and clean daily.

       o.  Police grounds and pick up any loose debris.

       Unless otherwise specified, all of the cleaning services listed shall be
       done five (5) days each week, Monday through Friday, except on Building
       holidays.

                                      -67-
<PAGE>
 
                                   EXHIBIT E
                                   ---------

                        SUBORDINATION, NON DISTURBANCE
                           AND ATTORNMENT AGREEMENT


    THIS AGREEMENT is made this 26th, day of February, 1999, by and between
EVERGREEN AMERICA CORPORATION, a New Jersey Corporation, Grantor,
AND
FOCAL COMMUNICATIONS CORPORATION OF NEW JERSEY, Grantee
AND
BANK OF TAIWAN, Holder of the Superior Interest.

                                  WITNESSETH:

    WHEREAS, Holder of the Superior Interest is the mortgagee under a Mortgage
dated September 15, 1997 covering certain land and building(s) known as Lot PL.
A in Block 104-105 on the Tax Map of the City of Jersey City, County of Hudson
and State of New Jersey (hereinafter "Premises"), which Mortgage is recorded in
the Office of the Hudson County Register at Book 6345 of Mortgages on Page 1
and the mortgagee under a Mortgage dated September 15, 1997, covering certain
land and building(s) known as Lot PL.1 in Block 73.74 on the Tax Map of Jersey
City, County of Hudson and State of New Jersey (hereinafter "Premises"), which
Mortgage is recorded in the Office of the Hudson County Register at Book 6344 of
Mortgages on Page 315; and

    WHEREAS, Grantor has conveyed to Grantee a Lease Agreement dated February 1,
1999 (hereinafter Lease Agreement), under the terms covenants, conditions and
agreements set forth therein; and,

    WHEREAS, Grantee desires to receive certain assurances from Holder of
Superior Interest that its possession and use of the Premises will not be
disturbed by Holder of Superior Interest in the event of a foreclosure or in the
event of a possessory action

                                      -68-
<PAGE>
 
by Holder of Superior Interest, at any time during the period of the Lease
Agreement, and Holder of Superior Interest is willing to grant certain
assurances upon the terms and conditions hereinafter set forth.

    NOW THEREFORE, the parties hereto, in consideration of the mutual covenants
and agreements herein contained, and intending to be legally bound hereby,
covenant and agree as follows:

    (1)  The Lease Agreement, and all of the right of Grantee thereunder, shall
be and are hereby made, and at all times hereafter shall be subject and
subordinate in all respects to the Mortgage of Holder of Superior Interest.
Notwithstanding such subordination, Grantee hereby agrees with Holder of
Superior Interest, immediately upon written demand, to attorn to and to
recognize Holder of Superior Interest, and any purchaser at foreclosure sale, as
the Grantor of the Lease Agreement for the balance of the term of the Lease
Agreement in accordance with the terms and provisions thereof, but subject,
nevertheless, to paragraph 2 and other provisions of this Agreement shall be
controlling in the event of any conflict.

    (2)  Grantee hereby agrees that Holder of Superior Interest or any purchaser
at foreclosure sale shall not be:

    (a)  Liable for any act or omission of the Grantor under said Lease
Agreement;

    (b)  Subject to any offsets or defenses which Grantee may have at any
time hereafter against Grantor.

    (c)  Bound by any rent that Grantee may have paid for more than the current
month to Grantor or any prior Grantor.

                                      -69-
<PAGE>
 
    (d)  Bound by any agreement between Grantor and Grantee to which Holder of
the Superior Interest had not previously consented in writing.

    (3)  So long as Grantee complies with all of the terms, covenants,
conditions and agreements set forth in the Lease Agreement, Grantee's possession
and use of the Premises under said Lease Agreement shall not be disturbed or
interfered with by Holder of Superior Interest or any purchaser at foreclosure
sale and Grantee shall not be joined in any foreclosure or possessory
proceeding.

    (4)  Grantee hereby agrees that any person or entity which at any time
hereafter becomes the Grantor under the Lease Agreement, including without
limitation, Holder of Superior Interest, or the purchaser at foreclosure sale
shall be liable only for the performance of the obligations of the Grantor under
said Lease Agreement during the period that they are Grantor and shall not be
liable for any obligation of the Grantor under said Lease Agreement which arose
prior to such period.

    (5)  This Agreement, except as otherwise specifically provided herein, shall
inure to the benefit of and be binding upon Holder of Superior Interest, its
heirs, executors, administrators, successors and assigns, Grantor, its heirs,
executors, administrators, successors and assigns, and Grantee, its successors
and assigns.

    (6)  Grantee covenants that the Lease has not been modified or altered and
that the Lease Agreement shall not, without the prior written consent of Holder
of the Superior Interest, be terminated, surrendered, modified or altered
hereafter.

                                      -70-
<PAGE>
 
    (7)  Grantee agrees that it will notify Holder of the Superior Interest in
writing, by certified mail, of any default by Grantor under the Lease Agreement
and shall not cancel or terminate the Lease without providing Holder of the
Superior Interest thirty (30) days from the date of such notice within which to
cure said default.  If any default by Grantor is cured within the time period
described above, Grantee shall have not right to cancel or terminate the Lease
Agreement by virtue of said default.

                                   EVERGREEN AMERICA CORPORATION



                                   BY: /s/ Howard Tung
                                      ----------------------------------
                                      HOWARD TUNG, Deputy Junior
                                      Vice President


                                   BANK OF TAIWAN



                                   BY: /s/ David Wen-Hsiung Chang
                                      ----------------------------------
                                      DAVID WEN-HSIUNG CHANG
                                      Senior Vice President &
                                      General Manager

                                      -71-

<TABLE> <S> <C>

<PAGE>
 
 
<ARTICLE> 5
<LEGEND>          This schedule contains summary financial information extracted
                  from the Consolidated Balance Sheet as of March 31, 1999 and
                  1998 and the Statement of Operations and Cash Flows for the
                  three months ended March 31, 1999 and 1998.
       
<S>                             <C>                    <C> 
<PERIOD-TYPE>                   3-MOS                  3-MOS
<FISCAL-YEAR-END>                         DEC-31-1998            DEC-31-1998
<PERIOD-START>                            JAN-01-1999            JAN-01-1998
<PERIOD-END>                              MAR-31-1999            MAR-31-1998
<CASH>                                    106,598,881            152,758,944
<SECURITIES>                                7,460,850                      0
<RECEIVABLES>                               7,935,803              6,242,879
<ALLOWANCES>                                1,960,000              1,046,000
<INVENTORY>                                         0                      0
<CURRENT-ASSETS>                          131,184,638            158,404,803
<PP&E>                                    100,595,860             19,386,802
<DEPRECIATION>                              9,872,098              1,260,951
<TOTAL-ASSETS>                            226,571,111            182,228,022
<CURRENT-LIABILITIES>                      11,775,331              5,753,632
<BONDS>                                   195,545,892            152,093,513
                               0                      0
                                         0                      0
<COMMON>                                          977                  1,150
<OTHER-SE>                                 21,713,718             24,110,505
<TOTAL-LIABILITY-AND-EQUITY>              226,571,111            182,228,022
<SALES>                                    26,003,897              5,102,448
<TOTAL-REVENUES>                           26,003,897              5,102,448
<CGS>                                      20,459,375              4,350,389
<TOTAL-COSTS>                              20,459,375              4,350,389
<OTHER-EXPENSES>                                    0                      0
<LOSS-PROVISION>                                    0                      0
<INTEREST-EXPENSE>                          4,097,502              1,093,250
<INCOME-PRETAX>                             1,447,020              (341,191)
<INCOME-TAX>                                        0                      0
<INCOME-CONTINUING>                         1,447,020              (341,191)
<DISCONTINUED>                                      0                      0
<EXTRAORDINARY>                                     0                      0
<CHANGES>                                           0                      0
<NET-INCOME>                                1,447,020              (341,191)
<EPS-PRIMARY>                                   16.46                 (3.86)
<EPS-DILUTED>                                   14.44                 (3.86)
        


</TABLE>


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