WINSTAR COMMUNICATIONS INC
8-K, 1999-01-11
TELEPHONE COMMUNICATIONS (NO RADIOTELEPHONE)
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                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                 --------------

                                    FORM 8-K

                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


        Date of Report (Date of earliest event reported) November 9, 1998


                          WINSTAR COMMUNICATIONS, INC.
               (Exact Name of Registrant as Specified in Charter)



         Delaware                   1-10726                 13-3585278
- - ----------------------------        ----------            -----------------
(State or Other Jurisdiction       (Commission           (IRS Employer
    of Incorporation)              File Number)          Identification No.)




230 Park Avenue, New York, New York                              10169   
- - ----------------------------------------                    -------------
(Address of Principal Executive Offices)                      (Zip Code)



Registrant's telephone number, including area code    (212) 584-4000



                                 Not Applicable
          ------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)



                             Exhibit Index -- Page 4



<PAGE>




ITEM 5.  OTHER EVENTS

         Purchase  of  IRU from Williams.  On December 17, 1998, our subsidiary,
WinStar Wireless,  Inc., entered into an agreement with Williams Communications,
Inc. to purchase from Williams a 25-year  indefeasible  right of use ("IRU") for
four strands of fiber optic cable on a national  route of 14,684  miles  (58,736
fiber miles) and a seven-year option to purchase two additional strands over the
same route  (29,638  fiber  miles).  This fiber  capacity is being  delivered as
routes are built and is expected to be completely  available by the end of 2001,
until  which time  Williams  will  fulfill  substantially  all of our  long-haul
transport  requirements  at no  additional  cost  to us.  We will  pay  Williams
approximately  $640  million over the next seven years for the IRU, the capacity
option,  certain  long-haul  transport and other network assets. We can exercise
the  capacity  option for  approximately  $51  million  payable  in cash  and/or
services.

         Sale of IRU to Williams.  On December 17, 1998, WinStar Wireless,  Inc.
and Williams entered into an agreement  providing for the sale by us to Williams
of a 25-year IRU for up to 2% of our current and future  local  Wireless  FiberK
capacity in the United  States.  Williams will pay us $400 million for this IRU,
with  payments  due ratably as we  construct  up to 270 hub sites.  We expect to
complete  construction  of at least  270 hub  sites  over the next  four  years.
Williams  will also pay us at least  $45.6  million  over a ten-year  period for
network maintenance services that we will provide over the term of the IRU.

         Purchase of Spectrum from CellularVision. On November 9, 1998, pursuant
to  an  Agreement  to  Purchase  LMDS  License   ("Purchase   Agreement")   with
CellularVision  USA,  Inc.  ("CVUSA")  and  CellularVision  of  New  York,  L.P.
("CVNY"),  dated July 10, 1998,  we purchased  from CVNY 850 MHz of the spectrum
covered by the LMDS A Block License issued to CVNY by the Federal Communications
Commission for the New York Primary Metropolitan Statistical Area for a purchase
price of  $32,500,000,  payable in cash.  The 850 MHz  portion of  spectrum  was
disaggregated by CVNY from the remaining spectrum covered by its license.


ITEM 7.  FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

   (c)   EXHIBITS:

          1    IRU  Agreement  between  WinStar  Wireless,   Inc.  and  Williams
               Communications, Inc. Dated December 17, 1998 (Long-Haul).

          2    Wireless  FiberK IRU Agreement By and Between  WinStar  Wireless,
               Inc. and Williams  Communications,  Inc. Effective as of December
               17, 1998.*

          3    Agreement  to Purchase  LMDS  License  dated July 10, 1998 by and
               between WinStar  Communications,  Inc.,  CellularVision USA, Inc.
               and CellularVision of New York, L.P.


_______________________________ 

*    Confidentiality for certain portions of these agreements is being sought by
     WinStar  Communications,  Inc. from the Securities and Exchange Commission.
     Accordingly, such portions have been redacted from these agreements.

                                        2
<PAGE>


                                    SIGNATURE


         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 hereunto duly authorized.

Date:    January 11, 1999

                                            WINSTAR COMMUNICATIONS, INC.

                                                  /s/ Kenneth J. Zinghini
                                            By: ____________________________ 
                                                Kenneth J. Zinghini
                         
                                       3
<PAGE>


         EXHIBIT INDEX


Exhibit   Document                                                       
- - -------   ---------                                                      

  10.1    IRU   Agreement   between   WinStar   Wireless,   Inc.   and  Williams
          Communications, Inc. Dated December 17, 1998 (Long-Hand).

  10.2    Wireless FiberK IRU Agreement By and Between WinStar Wireless, Inc.
          and Williams Communications, Inc. Effective as of December 17, 1998.

  10.3    Agreement to Purchase  LMDS License dated July 10, 1998 by and between
          WinStar Communications, Inc., CellularVision USA, Inc. and 
          CellularVision of New York, L.P.




_______________________________ 

*    Confidentiality for certain portions of these agreements is being sought by
     WinStar  Communications,  Inc. from the Securities and Exchange Commission.
     Accordingly, such portions have been redacted from these agreements.

                                       4

<PAGE>


                                                 Confidential - WinStar/Williams


                                  IRU AGREEMENT

                                     BETWEEN

                             WINSTAR WIRELESS, INC.

                                       AND

                          WILLIAMS COMMUNICATIONS, INC.


                             Dated December 17, 1998


                                   (Long-Haul)



<PAGE>


                                TABLE OF CONTENTS

1.   DEFINITIONS...........................................................1

2.   CONVEYANCE OF DARK FIBER IRUS AND GRANT OF OPTION.....................7
2.1.   Grant of Network IRU................................................7
2.2.   Option..............................................................8
2.3.   Financing Arrangements..............................................8
2.4.   Preferred Provider Status...........................................8
2.5.   Most Favored Customer Provision.....................................9
2.6.   No Title to Realty or Personalty....................................9

3.   CONSIDERATION FOR IRUS................................................10
3.1.   Contract Price......................................................10
3.2.   Exercise Price......................................................10

4.   CONSTRUCTION..........................................................10
4.1.   Construction Representations, Warranties and Covenants..............10
4.2.   Delivery of System Segments.........................................10
4.3.   Renewal of Required Rights..........................................11
4.4.   As-Built Drawings...................................................11
4.5.   Third-Party Consents................................................11

5.   ORDERING AND PROVISIONING.............................................12
5.1.   Provision of Interim Service........................................12
5.2.   Service Orders for Interim Services.................................12
5.3.   Changes in Service Parameters.......................................14
5.4.   Assignment and Assumption of Backbone Agreements....................15

6.   CONNECTION TO THE SYSTEM AND COLLOCATION..............................17
6.1.   Collocation.........................................................17
6.2.   Interconnection.....................................................17
6.3.   Ancillary Services..................................................18

7.   ACCEPTANCE AND TESTING OF FIBERS......................................18
7.1.   Overview............................................................18
7.2.   SSPFAT by Williams..................................................19
7.3.   SSPFAT by WinStar...................................................19
7.4.   Failure Notice......................................................20
7.5.   Correction..........................................................20
7.6.   Testing by Third Party..............................................20
7.7.   System Segment Fiber Acceptance Testing and Acceptance Date.........21
7.8.   Testing of Option Fibers............................................21

8.   USE OF THE SYSTEM.....................................................21
8.1.   Use of WinStar Fibers...............................................21
8.2.   Notice of Damage....................................................21
8.3.   Precautions.........................................................21
8.4.   Use of Equipment....................................................22
8.5.   Liens...............................................................22

9.   TERM..................................................................22
9.1.   Agreement Term......................................................22
9.2.   IRU Terms...........................................................22
9.3.   Effect of Termination...............................................22

<PAGE>

10.  OPERATION, MAINTENANCE, AND REPAIR OF THE SYSTEM......................23
10.1.  Routine Maintenance.................................................23
10.2.  Non-Routine Maintenance.............................................23
10.3.  Subcontractors......................................................23
10.4.  Continued Breach of  Routine Maintenance Obligations................23
10.5.  WinStar Equipment...................................................23
10.6   Access to Systems...................................................23

11.  RELOCATION............................................................24
11.1.  Relocation..........................................................24
11.2.  Cost of Relocation..................................................24
11.3.  Updated As-Built Drawings...........................................24

12.  INVOICING AND PAYMENT.................................................25
12.1.  Due Date and Invoice................................................25
12.2.  Form of Payment.....................................................25
12.3.  Disputed Charges....................................................25
12.4.  Late Interest.......................................................26
12.5.  Adjustments.........................................................26

13.  DISCLAIMER OF WARRANTIES..............................................26
13.1.  Parties.............................................................26
13.2.  Facility Owners/Lenders.............................................26

14.  AUDIT RIGHTS..........................................................26

15.  INDEMNIFICATION.......................................................27
15.1.  Indemnification.....................................................27
15.2.  Third Party Claims..................................................27
15.3.  Indemnification of Providers........................................28
15.4.  WinStar Customers...................................................28

16.  LIMITATION OF LIABILITY...............................................28
16.1.  General Intent......................................................28
16.2.  Liability Restrictions..............................................28
16.3.  Released Parties....................................................29

17.  INSURANCE.............................................................29
17.1.  Insurance...........................................................29
17.2.  Documentation.......................................................30
17.3.  Certificates........................................................30
17.4.  Blanket Policies....................................................30

18.  TAXES AND GOVERNMENTAL FEES...........................................30
18.1.  Payment by WinStar..................................................30
18.2.  Payment by Williams.................................................31
18.3.  Reimbursement.......................................................31
18.4.  Cooperation.........................................................31
18.5.  Services............................................................31

19.  NOTICE................................................................31

20.  CONFIDENTIALITY.......................................................32
20.1.  Confidential Information............................................32
20.2.  Obligations.........................................................32
20.3.  Exclusions..........................................................33
20.4.  No Implied Rights...................................................34

21.  DEFAULT...............................................................34

22.  FORCE MAJEURE.........................................................34
22.1.  Excusable Delay.....................................................34
22.2.  Notice and Remedy...................................................35
<PAGE>
23.  REMEDIES AND DISPUTE RESOLUTION.......................................35
23.1.  Dispute Resolution..................................................35
23.2.  Cumulative Remedies.................................................35
23.3.  Informal Dispute Resolution.........................................35
23.4.  Arbitration.........................................................36
23.5.  Continued Performance...............................................38
23.6.  Immediate Injunctive Relief.........................................38

24.  GENERAL...............................................................38
24.1.  Rules of Construction...............................................38
24.2.  Assignment..........................................................40
24.3.  Relationship of the Parties.........................................42
24.4.  Prohibition on Improper Payments....................................42
24.5.  Entire Agreement; Amendment; Execution..............................42

25.  REPRESENTATIONS, WARRANTIES AND COVENANTS.............................43
25.1.  Representations and Warranties......................................43
25.2.  Additional Williams Covenants.......................................43
25.3.  Infringement of Intellectual Property Rights........................44

26.  USE OF TELECOMMUNICATIONS AND OTHER SERVICES..........................44
26.1.  Condition to Provision of Services..................................44
26.2.  Intrastate Interexchange Services...................................44
26.3.  WinStar Responsibilities............................................45
26.4.  Consents............................................................45
26.5.  Restriction of Transmissions........................................45
26.6.  Reasonableness, Consents and Approval...............................45

                                    EXHIBITS

Exhibit A     Williams System
              Part 1 -- Route Map
              Part 2 -- System Segments
Exhibit B     Williams Network Pricing Schedules and Technical Specifications
Exhibit C     Collocation Provisions
              Part 1 - Transmission Sites
              Part 2 - POPs
Exhibit D     Fiber Splicing, Testing, and Acceptance Standards
Exhibit E     Fiber Specifications
Exhibit F     Cable Installation Specifications
Exhibit G     Transmission Site Specifications
Exhibit H     As-Built Drawing Specifications
Exhibit I     Operations Specifications
Exhibit J     Intentionally omitted
Exhibit K     Payment Terms
Exhibit L     Intentionally Omitted
Exhibit M     Intentionally Omitted
Exhibit N     Intentionally Omitted
Exhibit O     Williams Cities and Location of POPs



<PAGE>


                                  IRU AGREEMENT
                                   (Long-Haul)

         THIS IRU  AGREEMENT  (including  the  Exhibits and  Schedules  attached
hereto,  this "Agreement") is made as of the Effective Date (hereafter  defined)
by and between WINSTAR WIRELESS, INC. ("WinStar"), a Delaware corporation having
its principal  office at 230 Park Avenue,  New York City, New York, and WILLIAMS
COMMUNICATIONS,  INC. ("Williams"), a Delaware corporation, having its principal
office at One Williams Center, Tulsa, Oklahoma 74172.


                              W I T N E S S E T H:


         WHEREAS, Williams has constructed or will construct or obtain rights of
use in a fiber optic communication  system (the "System") located  approximately
along the routes  depicted in Exhibit A, Part 1 (the "Route") and  consisting of
the System Segments, as defined below; and


         WHEREAS, WinStar desires to acquire from Williams, and Williams desires
to provide  to  WinStar,  the  Network  IRU as defined  below upon the terms and
conditions set forth below;


         NOW, THEREFORE, in consideration of the mutual promises set forth below
and other good and valuable  consideration,  the  sufficiency of which is hereby
acknowledged, the parties hereby agree as follows:

1.       DEFINITIONS
         Capitalized  terms and phrases  used in this  Agreement  shall have the
following meanings:  

          (a)  "Acceptance Date" means the date defined in Section 7.7 below.

          (b)  "Acceptance Standards" means the standards set forth in Exhibit D
               with  respect  to  the  testing  of  the  WinStar   Fibers.   

          (c)  "Additional Services" means telecommunications services in excess
               of the Minimum  Commitment,  such  excess is not  included in the
               Contract Price.

          (d)  "Affiliate"  means, with respect to any entity,  any other entity
               Controlling,  Controlled  by or under  common  Control  with such
               entity,  whether  directly  or  indirectly  through  one or  more
               intermediaries.

          (e)  "Agreement"  has the  meaning  set forth in the  preamble to this
               document.  

          (f)  "Ancillary  Collocation  Services"  has the  meaning set forth in
               Exhibit C, Part 1, Section 1(d).

          (g)  "Ancillary Services" has the meaning set forth in Section 6.3.

          (h)  "Assignment  Agreement  Effective Date" has the meaning set forth
               in Section 5.4(a).

          (i)  "Assumed  Backbone  Agreement"  means a Backbone  Agreement  that
               WinStar assigns to Williams in accordance with Section 5.4.

                                       2

<PAGE>

          (j)  "Backbone  Agreements" means the agreements designated by WinStar
               that  WinStar  is a party to as of the  Effective  Date and which
               WinStar  intends to assign to Williams or have  Williams act as a
               payment agent.

          (k)  "Backbone  Agreement  Service  Provider"  means each  provider of
               telecommunications  services  (other than WinStar) who is a party
               to a Backbone Agreement.

          (l)  "Cable"  means  fiber  optic  cable  installed  pursuant  to this
               Agreement as part of the System (including any replacement cable)
               and fibers contained  therein,  including the WinStar Fibers, and
               associated  splicing  connections,  splice boxes and vaults,  and
               conduit.

          (m)  "Circuit" means a communications path with a specified bandwidth.

          (n)  "Claim" means any claim,  action,  dispute,  or proceeding of any
               kind between  WinStar (or any of its  Affiliates,  successors  or
               assigns) and Williams (or any of its Affiliates,  successors,  or
               assigns)  and any other  claim,  transaction,  occurrence,  loss,
               liability,  expense or other matter arising out of, in connection
               with, or in any way related to, the Network IRU, the System, this
               Agreement or any other  instrument,  arrangement or understanding
               related to the Network IRU.

          (o)  "Claimant" has the meaning set forth in Section 15.1.
               

          (p)  "Collocation  Service"  has the  meaning  set forth in Exhibit C,
               Part 2.


          (q)  "Connecting  Point" means a point where the network or facilities
               of WinStar will connect to the System.

          (r)  "Contract Price" has the meaning set forth in Section 3.1.

          (s)  "Control" and its derivatives mean legal, beneficial or equitable
               ownership,  directly or  indirectly,  of more than fifty  percent
               (50%) of the outstanding voting capital stock (or other ownership
               interest,  if not a  corporation)  of an entity or  management or
               operational control over such entity.

          (t)  "Costs"  means  actual,  direct  costs  incurred  and computed in
               accordance  with the  established  accounting  procedures used by
               Williams to bill third  parties for  reimbursable  projects.  All
               Costs shall be computed in  accordance  with  generally  accepted
               accounting  principles.  Such actual,  direct  costs  include the
               following:

               (i)  Labor costs,  including  wages and  salaries,  and benefits,
                    plus the overhead  allocable  to such labor costs  (overhead
                    allocation  percentage  shall not  exceed the lesser of: (i)
                    the percentage  Williams allocates to its internal projects;
                    or (ii) thirty percent  (30%));  and 

               (ii) Other   direct  costs  and   out-of-pocket   expenses  on  a
                    pass-through basis (such as equipment,  materials, supplies,
                    contract services, costs of capital, Required Rights, sales,
                    use or similar  taxes,  etc.) plus ten percent (10%) of such
                    expenses;  but, 

               (iii) Less any cost or expense reimbursed by a third party.

          (u)  "CPNIP"  has the  meaning  set  forth in Part I,  Section  2.1 of
               Schedule  B,  Williams  Network  Technical  Specifications.   

          (v)  "Deadline Date" has the meaning set forth in Section 4.2.

          (w)  "Deduction  Sections"  has  the  meaning  set  forth  in  Section
               24.1(l).

          (x)  "Dispute Notice" has the meaning set forth in Section 23.4(a).

          (y)  "Disputing Party" has the meaning set forth in Section 23.4.

          (z)  "Due Date" has the meaning set forth in Section 12.1.

          (aa) "Effective Date" means December 17, 1998.

          (bb) "Equipment"  has the meaning set forth in Section 1.1 of Schedule
               C, Part 2.

          (cc) "Exercise  Date" means the date on which  WinStar  exercises  its
               Option in accordance with Section 2.2.

          (dd) "Exercise Price" has the meaning set forth in Section 3.2.

          (ee) "Facility  Owners/Lenders" means any entity (other than Williams)
               that:  (a) owns any  portion  of the  System or any  property  or
               security interest therein, (b) leases to Williams, or provides an
               IRU to Williams in, any portion of the System, or (c) is a Lender
               with respect to Williams or any Affiliates of Williams.

          (ff) "FCC" means the Federal Communications Commission.

          (gg) "Fiber  Acceptance  Testing" means the fiber  acceptance  testing
               described in Exhibit D and in Article 7.

          (hh) "Fiber Collocation  Provisions" means the provisions set forth in
               Exhibit C, Part 1.
               

          (ii) "Fibers"  means  any  optical  fibers  contained  in  the  System
               including  the WinStar  Fibers,  the fibers of  Williams  and the
               fibers of any third party in the System excluding,  however,  any
               fibers  granted  (whether  through  ownership,   IRU,  lease,  or
               otherwise)  to  governmental  entities in exchange for the use of
               streets,  rights of way, or other property under the jurisdiction
               of such entity.

          (jj) "Force Majeure Events" has the meaning set forth in Article 22.

          (kk) "Indefeasible   Right  of  Use"  or  "IRU"  means  an  exclusive,
               indefeasible  right to use the specified  property or capacity in
               the manner  contemplated  by this Agreement;  provided,  however,
               that the grant of an IRU shall not convey  title,  ownership,  or
               rights of  possession  in the  System,  the WinStar  Fibers,  the
               Cable, the Right-of-Way Agreements, or any other real or personal
               property.

 
                                      3

<PAGE>

          (ll) "Indemnitor" has the meaning set forth in Section 15.1.

          (mm) "Initial  WinStar  Fibers"  has the  meaning set forth in Section
               2.1.

          (nn) "Intellectual   Property   Rights"   means   patent,   copyright,
               trademark,  trade secret or other proprietary rights with respect
               to any work product in which such rights could inure.

          (oo) "Interconnect/Collocation  Notice"  has the  meaning set forth in
               Exhibit C, Part 1, Section 3.

          (pp) "Interconnect  Facility"  has the meaning set forth in Exhibit C,
               Part 1, Section 2(a).

          (qq) "Interconnection"  has the meaning set forth in Section 6.2. 

          (rr) "Interim IRU" has the meaning set forth in Section 2.1(b).

          (ss) "IRU Term" has the meaning set forth in Section 9.2.

          (tt) "LEC" means a local exchange carrier.

          (uu) "Lender" has the meaning set forth in Section 2.3.

          (vv) "Losses"  means all  liabilities,  damages and related  costs and
               expenses (including fines, levies, assessments,  reasonable legal
               fees and disbursements  and costs of  investigation,  litigation,
               settlement,  judgment,  interest and penalties) directly incurred
               by a party.

          (ww) "Material  Improvements"  has the meaning set forth in Section 10
               of Exhibit C, Part 2.

          (xx) "Mean Time to Restore" has the meaning set forth in Exhibit B.

          (yy) "Minimum  Commitment"  means One Hundred Twenty  Million  Dollars
               ($120,000,000),   which  is  the   minimum   amount   of   On-Net
               Telecommunications  Services  in  United  States  dollars  to  be
               purchased  by WinStar  pursuant to the terms  hereof prior to the
               expiration of the fifth  anniversary of the Effective  Date. Such
               amount is included in the Contract Price.

          (zz) "Minimum  Term  Liability"  has the  meaning set forth in Section
               5.3(b).

          (aaa)"NCC" means Network  Control  Center,  as set forth in Exhibit I,
               Section  1(A).  

          (bbb) "Network IRU" has the meaning set forth in Section 2.1.

          (ccc)"Notice  of  Election"  has the  meaning  set  forth  in  Section
               15.2(a).

          (ddd)"OOS"  means  Out-of-Spec,  as set forth in  Exhibit  D,  Section
               1(B).

          (eee) "Off Net" means a Circuit that is not On Net.

                                       4
<PAGE>


          (fff)"On Net" means a Circuit  traversing the Williams Network between
               two Williams points of presence.

          (ggg) "Option Fibers" has the meaning set forth in Section 2.1.

          (hhh) "Option" has the meaning set forth in Section 2.2.

          (iii)"OTDR" means optical time domain  reflectometer,  as set forth in
               Exhibit D, Section 1(A).

          (jjj)"Other Services" means local access,  Interconnection,  Ancillary
               Services and Collocation Services.
               

          (kkk)"Payment  Deductions"  has  the  meaning  set  forth  in  Section
               24.1(l).

          (lll) "Payment Terms" has the meaning set forth in Section 3.1.

          (mmm)"Point of Presence" means a specified  location at which Williams
               originates or terminates services.

          (nnn) "Premises" has the meaning set forth in Exhibit C, Part 2.

          (ooo)"Prime  Rate"  means,  with  respect  of  any  period,  the  rate
               published  as Chase  Manhattan's  prime  rate in the Wall  Street
               Journal, or any successor  publication thereto, from time to time
               during such period.

          (ppp)"Pro-Rata  Share"  means a  proportion  equal to a fraction,  the
               numerator  of which  is the  number  of  WinStar  Fibers  and the
               denominator of which is all Fibers in the relevant System Segment
               Portion(s). If this fraction varies over different System Segment
               Portions,  then the Pro Rata Share shall be equal to the weighted
               average  (weighted by length as set forth in  Williams'  as-built
               drawings) of the relevant System Segment  Portions.  For example,
               if the  fraction  for 100  feet of the  relevant  System  Segment
               Portion is 0.1 and the fraction for the  remaining 50 feet of the
               relevant System Segment Portion is 0.07, the weighted average for
               the entire System Segment Portion would be 0.09.

          (qqq)"Released  Party"  means  each  of the  following  (but  excludes
               Williams and WinStar): 

               (i)  Any  Affiliates  or  Lenders  of the  other  party  and  any
                    Facility Owners/Lenders;

               (ii) Any  employee,  officer,  director,  stockholder,   partner,
                    member,  or trustee of the other party or of its Affiliates,
                    Lenders, or Facility Owners/Lenders; or

               (iii)Assignees   of  the   entities   included   in   the   above
                    subparagraphs   (a)  or  (b)  and  any  employee,   officer,
                    director,  stockholder,  partner, member, or trustee of such
                    assignees.

          (rrr)"Renegotiated  Backbone  Agreement"  means  an  Assumed  Backbone
               Agreement that Williams has  renegotiated as set forth in Section
               5.4(b).

                                       5
<PAGE>

          (sss) "Representatives" has the meaning set forth in Section 20.2.

          (ttt)"Requested  Start  Date" has the  meaning  set  forth in  Section
               5.2(b).

          (uuu) "Required Rights" has the meaning set forth in Section 4.1.

          (vvv) "Restricted Fiber" has the meaning set forth in Section 26.1.

          (www)"Right-of-Way     Agreements"     means     rights,     licenses,
               authorizations,  easements,  leases, fee interests, or agreements
               that provide for the  occupancy by the System of real property or
               fixtures  (such  as  conduit,   bridges,   river  crossings,   or
               transmission towers).

          (xxx) "Route" has the meaning set forth in the Recitals above.

          (yyy) "Routine Maintenance" has the meaning set forth in Section 10.1.
               

          (zzz)"Service  Orders" has the  meaning  set forth in Section  5.2(a).
               

          (aaaa)  "Service   Term"  means  with  respect  to  the  provision  of
               Telecommunications   Services,   Additional   Services  or  Other
               Services,  the length of time specified in the applicable Service
               Order during which Williams will provide such  Telecommunications
               Services, Additional Services or Other Services.

          (bbbb) "Space" has the meaning set forth in Section 1.1 of Schedule C,
               Part 2.
               

          (cccc) "Start  Date"  means,  with  respect to any  Telecommunications
               Services or Other Services WinStar  requests  Williams to provide
               hereunder, the first day on which such services are provided.
               

          (dddd) "Start of Service  Notice" or "SOSN" has the  meaning set forth
               in Section 5.2(e) .

          (eeee)  "System"  shall  have the  meaning  set forth in the  Recitals
               above.

          (ffff) "System  Segment"  means  one of the  System  Segment  Portions
               identified as a System Segment in Exhibit A, Part 2.

          (gggg) "System Segment Portion" means a discrete portion of the System
               and may refer to a span (a  portion  of the  System  between  two
               Transmission  Sites or between a Transmission Site and a point of
               presence  or System end point),  a portion  between two points of
               presence  or a point of  presence  and a System end  point,  or a
               portion  of  the  System   affected  by  a  relocation  or  other
               circumstance.

          (hhhh)     "Telecommunications     Services"    means    interexchange
               telecommunications   capacity  on  Williams'  Network  (or  third
               parties' telecommunications  facilities) at the DS-3, OC-3, OC-12
               and OC-48 levels but excluding Other Service.

          (iiii) "Term" has the meaning set forth in Section 9.1.

          (jjjj) "Third Party Service  Provider" means any third party provider,
               operator or maintenance repair contractor of facilities  employed
               by Williams in connection  with the provision of the Network IRU,
               Telecommunications Services or Other Services.

                                       6

<PAGE>

          (kkkk) "Transmission Sites" means the optical amplifier,  regenerator,
               and junction sites along each System Segment.

          (llll)  "Williams"  means  Williams  Communications,  Inc., a Delaware
               corporation, formerly known as Vyvx, Inc.

          (mmmm)  "Williams  Network"  means the  telecommunications  facilities
               owned  or  operated  by  Williams  and used to  provide  services
               between  the cities  listed on Exhibit O, as such may be added to
               as Williams grows its network during the Term.

          (nnnn) "WinStar"  has the meaning set forth in the first  paragraph of
               this document.

          (oooo)   "WinStar   Equipment"   means   optronic   (opto-electrical),
               electronic,  or optical equipment, or materials,  facilities,  or
               other  equipment  (other than the System)  owned,  possessed,  or
               utilized by WinStar.

          (pppp) "WinStar Facilities" has the meaning set forth in Section 26.3.

          (qqqq) "WinStar  Fibers"  means the Initial  WinStar  Fibers and, upon
               WinStar's  exercise of the Option in accordance with Section 2.2,
               the Option Fibers.

          (rrrr) "WinStar IRU" has the meaning set forth in Section 2.1. 

2.   CONVEYANCE OF DARK FIBER IRUS AND GRANT OF OPTION 

     2.1. Grant of Network IRU.

     Williams  hereby  grants  the  "Network  IRU" to WinStar  for the  purposes
     described  herein and on the terms and subject to the  conditions set forth
     herein. The Network IRU comprises:

     (a)  An exclusive  Indefeasible Right of Use (the "WinStar IRU"), effective
          as of the Acceptance  Date for each System  Segment,  in: 

          (i)  Four (4) strands of optical fiber (the "Initial WinStar Fibers"),
               as identified by Williams in each System Segment,  throughout the
               length of the Route;  and 

          (ii) If the  Exercise  Date  occurs,  two (2)  additional  strands  of
               optical fiber (the "Option Fibers"), as identified by Williams in
               each System Segment,  throughout the length of the Route; and 

     (b)  An exclusive  Indefeasible  Right of Use in On-Net  Telecommunications
          Services (the  "Interim  IRU"),  effective as of the  Effective  Date,
          which is further defined in Article 5. 

     2.2. Option.

     (a)  WinStar is hereby  granted an option (the  "Option")  to an  exclusive
          Indefeasible Right of Use in the Option Fibers in all System Segments.
          The Option is not divisible  (i.e. it may not be exercised in part) by
          System Segment or strand of Option Fiber. If not exercised, the Option
          shall expire on the seventh (7th)  anniversary of the Effective  Date.
     

     (b)  WinStar may  exercise  the Option  only by delivery of an  irrevocable
          written  notice to that  effect by an  authorized  representative.  If
          WinStar so exercises the Option:  

          (i)  The Option Fibers will be deemed to be WinStar Fibers (except for
               purposes of Article 7, for which separate  treatment is indicated
               in Section  7.8) and will be deemed to be subject to the  WinStar
               IRU;  and 

          (ii) WinStar's  rights to use the Option  Fibers  shall begin upon the
               initial  payment  of  the  Exercise  Price  (or,  if  later,  the
               Acceptance Date for each System Segment) and shall continue until
               the last day of the IRU Term of the corresponding System Segment.


     2.3. Financing Arrangements.

     Each party may,  directly  or through an  Affiliate,  enter into  financing
     arrangements  (including  secured  loans,  leases,  sales with  lease-back,
     leases with lease-back  arrangements,  purchase-money  or vendor financing,
     conditional  sales  transactions  or other  arrangements)  with one or more
     financial institutions, vendors, suppliers or other financing sources (each
     a "Lender"), that, with respect to Williams, relate to the System and, with
     respect to  WinStar,  relate to the  Network  IRU (and not to any  physical
     property right in the System),  subject to Williams' rights pursuant to the
     Payment Terms. 

     2.4. Preferred Provider Status.

     (a)  During the Term,  WinStar  shall  first  seek to obtain  its  domestic
          interexchange  telecommunications  requirements (including dark fiber,
          data,  voice and video  circuits) from Williams.  WinStar will fulfill
          such  requirements  with  Williams'   telecommunications  products  if
          Williams is responsive to WinStar's requests and those products,  when
          compared to similar offerings in the marketplace, are of equivalent or
          better quality,  availability and price. 

     (b)  Within 180 days after the  Effective  Date,  the parties  will jointly
          establish a  benchmarking  measurement  and  comparison  process  (the
          "Benchmarking  Process") designed to objectively  evaluate whether the
          Williams  Telecommunications  Services,  Additional  Services or Other
          Services,  as  applicable,   are  of  equivalent  or  better  quality,
          availability  and price as  compared  to  similar  services  generally
          available  in the  market  for  similar  size and  scope  requirements
          ("Market  Level  Charges").  The  Benchmarking  Process will take into
          consideration  relevant  factors such as quality and  delivery  terms.

     2.5. Most Favored Customer Provision.

     During the Term,  if Williams  sells  On-Net  Telecommunications  Services,
     On-Net  Additional  Services,  and/or Other Services (but not including any
     local  access or dark/dim  fiber) to a third party on  Financial  Terms (as
     hereinafter  defined) that are not Comparable (as  hereinafter  defined) to
     those provided hereunder, WinStar shall be entitled to an adjustment of the
     amounts paid with regard to the On-Net Telecommunications  Services, On-Net
     Additional  Services,  and/or Other  Services in question.  Williams  shall
     promptly notify WinStar in writing of such more favorable  Financial Terms.
     Williams  shall be under no  obligation to disclose to WinStar the identity
     of any such third party or any other provisions of such a contract that are
     not more favorable than those provided to WinStar. Such adjustment shall be
     equal  to the  aggregate  amount  necessary  to make  the  Financial  Terms
     Comparable  (pro rated to follow the cash timing of this  Agreement).  Upon
     payment or credit of such  adjustment to WinStar,  the  Financial  Terms of
     this Agreement  shall be deemed to be those more favorable  Financial Terms
     for the purpose of future  applications  of this  Section.  Nothing in this
     Section  shall be deemed to require  Williams to sell more than the Minimum
     Commitment  contained herein.  "Comparable"  means not less than the price,
     after  adjustments  to take into account all  differences  attributable  to
     volume,  terms and  conditions,  advances in  technology,  passage of time,
     market conditions or strategic relationship value.  "Financial Terms" means
     the overall pricing of services to the third-party.

     2.6      No Title to Realty or Personalty.

     Neither this  Agreement  nor the grant of the Network IRU  effected  hereby
     conveys  any  form or type  of  title  in any  real or  personal  property,
     including the System or any portion thereof or in any transmission or other
     facilities  and equipment  related to the  provision of  Telecommunications
     Services,  Other  Services,  or Additional  Services.  Williams and WinStar
     intend that this  Agreement  constitutes a true lease of the WinStar Fibers
     and not a sale of the WinStar Fibers.  Notwithstanding  such express intent
     of the parties, if a court of competent  jurisdiction  determines that this
     Agreement  is not a true  lease,  but a security  interest  in the  WinStar
     Fibers,  then  solely in that  event and  solely  for the  limited  purpose
     thereof,  WinStar  shall be  deemed to have  granted  Williams  a  security
     interest  as  described  in  Section 7 of Exhibit K hereto.  WinStar  shall
     provide an inventory of any equipment to be located on Williams'  sites. 

                                       9
<PAGE>

3.   CONSIDERATION FOR IRUS 

     3.1. Contract Price.

     As  consideration  for the Network IRU,  WinStar  shall pay  Williams  Five
     Hundred and Fifty Million Dollars  ($550,000,000) (the "Contract Price") in
     accordance  with the  payment and other terms set forth in Exhibit K hereto
     (the "Payment Terms"),  plus the Exercise Price if the Option is exercised.
     
     3.2. Exercise Price.

     The price payable if WinStar  exercises the Option (the  "Exercise  Price")
     shall be Fifty-One Million Eight Hundred  Thirty-Four  Thousand One Hundred
     Dollars  ($51,834,100),  allocated  to each System  Segment as set forth in
     Exhibit A, Part 2. The  Exercise  Price for each  System  Segment  shall be
     chargeable  upon the later of (a) the date WinStar  exercises the Option or
     (b) the  Acceptance  Date of that  System  Segment.  

4.  CONSTRUCTION  

     4.1. Construction Representations, Warranties and Covenants.

     (a)  Williams represents, warrants and covenants that, as of the Acceptance
          Date for each System Segment,  it (or the underlying facility owner on
          Williams'   behalf)   shall  have   obtained  the   following   rights
          (collectively, the "Required Rights"): 

          (i)  All  Right-of-Way  Agreements  necessary for the installation and
               use of that System  Segment;  

          (ii) The rights to use those System  Segment  Portions it does not own
               and the  right to grant  the  Network  IRU with  respect  to such
               System Segment Portions;  

     (b)  Williams  represents,  warrants and  covenants  that,  for each System
          Segment,  

          (i)  That System Segment has been designed, engineered, installed, and
               constructed in accordance  with the  specifications  set forth in
               Exhibits  D, E, F and G; and 

          (ii) Throughout the relevant IRU Term, the exercise of rights by or on
               behalf of Williams'  Facilities  Owners/Lenders shall not deprive
               WinStar of the peaceful and quiet enjoyment of the WinStar IRU in
               that System Segment. 

     4.2. Delivery of System Segments.

     (a)  Deadline  Date.  The planned  Acceptance  Date for each System Segment
          shall be the date sixty (60) days after the Planned  Construction Date
          set forth as such in Exhibit A, Part 2. The  "Deadline  Date" shall be
          sixty (60) days after the later of (a) such planned Acceptance Date or
          (b) the planned  Acceptance  Date as extended due to unforseen  events
          not in the  reasonable  control  of  Williams  (other  than  as due to
          Williams' negligence),  Force Majeure Events or as expressly permitted
          by this  Agreement.  Williams  shall  implement each System Segment so
          that it achieves its Acceptance  Date by the Deadline  Date.  Williams
          shall give WinStar as much prior notice as reasonably possible if , to
          the best of Williams'  knowledge,  there is a forseeable  risk that it
          may miss a Deadline Date for any System  Segment.  

                                       10
<PAGE>

     (b)  Failure to Meet Deadline  Date. If Williams does not meet the Deadline
          Date for any System  Segment,  and the  parties  are  unable,  in good
          faith,  to agree to an alternative  Deadline Date,  WinStar's sole and
          exclusive  monetary  remedy for such failure  shall be to obtain Cover
          (as hereinafter defined) beginning on the Deadline Date for the System
          Segments  not made  available.  Such  "Cover"  shall be  satisfied  by
          Williams'  providing,  at Williams'  expense:  (a) such capacity as is
          required for WinStar to carry those Circuits it would have migrated to
          the  WinStar  Fibers,  and (b) such  other  capacity  as is  needed to
          fulfill  WinStar's  increase in usage  (based on actual  orders of its
          customers),  until Williams delivers the WinStar Fibers. In any event,
          Williams  will provide such Cover  capacity in ATM,  private  line, or
          frame relay formats,  at WinStar's  option.  

     4.3.  Renewal of Required Rights.

          Williams  shall  renew or replace  existing  Required  Rights for each
          System Segment through at least the applicable IRU Term. 

     4.4. As-Built Drawings.

          Within  six (6)  months  after  the  Acceptance  Date  for any  System
          Segment,  Williams  shall provide  WinStar with as-built  drawings for
          that  System  Segment,  in  compliance  with  the  specifications  for
          as-built drawings set forth in Exhibit H. 

     4.5. Third-Party Consents.

          WinStar  acknowledges  that  Williams  requires the consent of a third
          party  in  order  to  grant   WinStar  an  IRU  with  respect  to  the
          Washington-Houston  and Houston-Dallas System Segments.  WinStar shall
          not  unreasonably  withhold  consent  to  changes  to  this  Agreement
          required by such third party that do not  adversely  affect  WinStar's
          rights and obligations under this Agreement and do not require payment
          of additional  consideration  by WinStar.  If WinStar consents to such
          changes,  the  parties  shall  execute an  appropriate  amendment.  If
          WinStar does not consent to such  changes,  or the  Required  Consents
          cannot be obtained  for other  reasons,  then the  Contract  Price and
          Exercise  Price  shall  each be reduced  by the  corresponding  amount
          allocated to the affected  System  Segment(s) in Exhibit A, Part 2. 

                                       11
<PAGE>

5.   ORDERING AND PROVISIONING 

     5.1. Provision of Interim Service.

     (a)  Inasmuch as the deployment of the System does not currently  reach all
          locations  set forth in Part 1 of Exhibit A, Williams  shall  provide,
          subject   to   availability   and  on  a   non-discriminatory   basis,
          Telecommunications Services on the Williams Network in accordance with
          the terms of this Agreement.  Such Telecommunications  Services may be
          part of the Minimum Commitment or may be Additional  Services.  

     (b)  At the request of Williams,  WinStar  shall pay for Other  Services or
          Additional  Services requested by WinStar in accordance with the terms
          of this Agreement. 

     (c)  Within ninety (90) days after each of the first five (5) anniversaries
          of the Effective Date,  Williams shall determine  WinStar's actual use
          of Minimum  Commitment  for the year  ending on such  anniversary  and
          shall send such information to WinStar for review. Irrespective of any
          shortfall in Minimum  Commitment  actually used by WinStar  during any
          period,  in no event  shall any  refund,  rebate or  reduction  in the
          Contract  Price be  granted or paid to WinStar as a result of any such
          shortfall.  Williams  shall be  obligated  to  accept  any  conforming
          Service  Orders  issued  by  WinStar  for  On-Net   Telecommunications
          Services  up  to  the  Minimum   Commitment   during  the  first  five
          anniversaries of the Effective Date.  Williams shall permit WinStar to
          take up to two (2)  months  beyond  the fifth  anniversary  beyond the
          Effective Date to use  Telecommunications  Services requested and paid
          for  under a  Service  Order for  On-Net  Telecommunications  Services
          issued prior to the end of the fifth anniversary of the Effective Date
          to enable WinStar to meet the Minimum Commitment.  Notwithstanding the
          foregoing,  WinStar  shall have  additional  time beyond the foregoing
          five  year  period  to  meet  the  Minimum  Commitment  to the  extent
          WinStar's  failure to meet the Minimum  Commitment is due to delays by
          Williams' in providing any of the On-Net  Telecommunications  Services
          by the firm order  commitment date issued by Williams during such five
          year period. 

     5.2. Service Orders for Interim Services.

     (a)  Telecommunications  Services,  Additional Services, and Other Services
          requested by WinStar  hereunder shall be requested on Williams Service
          Order  forms in effect  from  time to time  ("Service  Orders").  Each
          Service Order shall  reference this Agreement.  Williams  reserves the
          right not to accept a Service  Order  that does not  conform  with the
          terms and conditions of this Agreement and such non-conforming Service
          Order shall have no force or effect hereunder.  

                                       12

<PAGE>

     (b)  Each Service Order will indicate a requested due date (the  "Requested
          Start  Date")  for the  Circuit,  the  desired  term  of the  Circuit,
          specific city pairs, applicable bandwidth,  whether the Circuit(s) are
          to be  expedited  or  provided  in  normal  intervals  and  any  other
          parameters required. Williams shall acknowledge receipt of the Service
          Order,    on   average,    within    forty-eight    (48)   hours   (an
          "Acknowledgement").   Within   four   (4)   business   days   of   the
          Acknowledgement,   Williams   will   advise   WinStar  as  to  network
          availability.  With respect to On-Net Circuits,  when WinStar requests
          to order its own local loops  Williams will provide a Letter of Agency
          within  seven to ten  business  days  after  Williams'  receipt of the
          Service Order.  Within  twenty-four (24) hours after Williams' receipt
          of the Design  Layout  Record (as  provided  by the  applicable  local
          access  provider),  Williams will provide a firm order  commitment for
          On-Net  Circuits.  All Service Order intervals for Off-net Circuits or
          Backbone Agreement Circuits are on an individual case basis.  Williams
          will use reasonable efforts to assist WinStar in obtaining a Letter of
          Agency and delivering service from a Third-Party Provider.  All On-Net
          DS-3/OC-3 Circuits ordered by WinStar pursuant to Service Orders under
          this  Agreement  will be  provisioned  by  Williams  within  a  target
          timeframe of  forty-five  (45) days from the date of the Service Order
          for POP to POP service.  

     (c)  Once a Service  Order is placed,  WinStar may cancel it only by notice
          of  cancellation  not  less  then ten days  prior to  delivery  of the
          corresponding  Circuit, and payment of any specified cancellation fee.
          WinStar   agrees  that  the  actual  damages  in  the  event  of  such
          cancellation  would be difficult or impossible to ascertain,  and that
          the cancellation  charge set forth in herein is consequently  intended
          to  establish   liquidated   damages  and  not  a  penalty.   

     (d)  Any   conflicting,   different  or  additional  terms  and  conditions
          contained in WinStar's  acknowledgment  or Service  Order or elsewhere
          are deemed  objected to by Williams and shall not  constitute  part of
          this Agreement.  No action by Williams (including  fulfillment of such
          Service  Order) shall be  construed  as binding or estopping  Williams
          with  respect to such  conflicting,  different or  additional  term or
          condition,  unless the Service Order containing said term or condition
          has been  signed by an  authorized  representative  of  Williams.  

     (e)  Williams shall make reasonable  efforts to provide  Telecommunications
          Services,  Other Services and Additional  Services within its standard
          service  implementation  interval, as set forth herein or on WinStar's
          Requested Start Date.  Telecommunications  Services, Other Services or
          Additional Services,  as applicable,  shall begin on the date Williams
          issues a notice  that  service  is  available  (the  "Start of Service
          Notice" or "SOSN"), indicating the service has been tested by Williams
          in accordance  with  Williams'  standard  specifications  and that the
          service  meets  or  exceeds  those  specifications.  

                                       13

<PAGE>

     (f)  WinStar may  reasonably  request  one or more delays in the  Requested
          Start Date of a Service  Order, a move, or  rearrangement  if Williams
          receives  the delay  request at least  fifteen  (15) days prior to the
          Requested  Start  Date and the  requested  delay  does not  extend the
          Requested Start Date more than thirty (30) days from the original date
          thereof.  If WinStar delays the Requested  Start Date (or as gauged by
          the SOSN, if issued for a date after the Requested Start Date) by more
          than  thirty  (30)  days,  WinStar  has the  option to (a)  accept the
          billing   for  the   Service   Order,   (b)  in  the  case  of  On-Net
          Telecommunications  Services,  Other Services, or Additional Services,
          cancel the Service Order and pay the applicable  cancellation  charges
          for  the   facilities   ordered,   or  (c)  in  the  case  of  Off-Net
          Telecommunications  Services,  Other Services, or Additional Services,
          cancel the Service  Order and pay any charges or other costs  Williams
          incurs as a result of such  cancellation.  The billing or cancellation
          will be effective  thirty (30) days after the Requested Start Date. If
          WinStar elects to accept billing,  the installation  will be completed
          as soon as reasonably  practical after WinStar  advises  Williams that
          the installation can be completed. 

     (g)  Subject to the terms of Section 24.1(l),  if, after the relevant Start
          Date, Williams is in material breach of its obligation to issue a SOSN
          for On-Net  Telecommunications  Services (excluding any breach arising
          from delays in  obtaining  or  failures to obtain or maintain  service
          such as local  access or Off-Net  service,  but  excluding  POP-to-POP
          On-Net  service)  for a period of more than one hundred  twenty  (120)
          consecutive days after WinStar provides written notice of such breach,
          WinStar may deduct from each succeeding  monthly  invoice,  so long as
          that  breach  continues,  the amount by which such  Telecommunications
          Services  would   otherwise  have   contributed   toward  the  Minimum
          Commitment  during any month  following  such one hundred twenty (120)
          day period.  Upon  Williams'  issuance of the  corresponding  SOSN, no
          further   deductions   shall  be   available   to  WinStar   for  such
          Telecommunications Services. 

     5.3. Changes in Service Parameters.

     (a)  WinStar  may  disconnect  Off-Net  Telecommunications  Service,  Other
          Services,  or Additional  Services  provided by a Third-Party  Service
          Provider  pursuant to a Service  Order by  providing  sixty (60) days'
          prior written notice and paying any and all amounts  properly due that
          Provider for the affected  Service  Order.  

     (b)  Following the relevant Start Date for any On-Net service,  WinStar may
          disconnect  or  reconfigure  that  service upon sixty (60) days' prior
          written notice.  If that action relates to a Circuit that has not been
          in place for at least one (1) year from its Start  Date,  (i)  WinStar
          shall pay Williams an amount equal to the total of the monthly charges
          for one year of  service of such  Circuit,  less the amount of monthly
          charges  actually  paid at the  time  of  service  disconnection  (the
          "Minimum Term  Liability")  and (ii),  WinStar shall also pay Williams
          the additional charges set forth in this Agreement that are associated
          with that disconnection or reconfiguration. Subsection (ii) shall also
          apply in the  event  of a  cancellation  in  accordance  with  Section
          5.2(c).

                                       14

<PAGE>

     5.4. Assignment and Assumption of Backbone Agreements.

     (a)  Assumption.  Subject to subsection (i) below and WinStar obtaining any
          necessary required consents,  WinStar will assign to Williams pursuant
          to a mutually  acceptable  assignment  and assumption  agreement,  all
          Backbone Agreements that can be assigned,  to the extent that Williams
          has the requisite intrastate or international authority to provide the
          services  encompassed  by such  Backbone  Agreements.  The date of the
          assignment shall be the "Assignment  Agreement  Effective Date". After
          such  assumption,  the terms and  conditions of such Assumed  Backbone
          Agreements or such  Renegotiated  Backbone  Agreement,  as applicable,
          (including all technical standards and service provisioning intervals)
          shall prevail  solely with regard to services  provided by Williams to
          WinStar  thereunder,  except as to any Circuit which has been migrated
          on Williams  Network as provided below.  

     (b)  Renegotiation.   Williams  shall   renegotiate  the  Assumed  Backbone
          Agreements,  as it is  reasonably  able,  to  improve on the terms and
          pricing thereof.  Any such renegotiated terms shall only be applicable
          to  WinStar  to the extent it  improves  the terms and  pricing of the
          Backbone  Agreement as assigned to Williams.  Once an Assumed Backbone
          Agreement  is  renegotiated,  it shall be  considered  a  Renegotiated
          Backbone  Agreement for all purposes  herein.  Williams will only pass
          through to WinStar,  and WinStar  shall be entitled  to, its  pro-rata
          share of such  cost  savings  achieved  in any  Renegotiated  Backbone
          Agreement. WinStar's pro-rata share will be determined by dividing the
          then  current  WinStar  Circuit  or  billing  volumes by the total new
          Circuit or billing volume under the Renegotiated  Backbone  Agreement.
         

     (c)  Payment Agent.  WinStar shall designate  Williams as its payment agent
          with  respect to all  Backbone  Agreements  that cannot be assigned to
          Williams pursuant to subsection (a) above.

     (d)  Payment  and  Minimum  Commitments.  WinStar  shall pay  Williams  for
          services   rendered   under  the  Assumed   Backbone   Agreements  and
          Renegotiated  Backbone  Agreements at the rates therein and shall also
          remain  responsible  for meeting  the  associated  minimum  revenue or
          volume  commitments,  if any (the  "Minimums").  With  respect  to any
          Renegotiated   Backbone   Agreement,   WinStar   shall  abide  by  the
          renegotiated terms and conditions,  including paying the reduced price
          as set forth in subsection (b) above.  WinStar shall, in all instances
          and  to  the  extent  such   amounts  are   pre-calculated,   pay  the
          non-recurring and monthly recurring charges to Williams in immediately
          available  funds at least  one  billing  cycle  prior to the date that
          payment  is due  from  Williams  to  the  Backbone  Agreement  Service
          Provider  under  an  Assumed  Backbone  Agreement  or  a  Renegotiated
          Backbone Agreement. 


                                       15
<PAGE>

     (e)  Administration.  The  parties  will  work  together  to  identify  the
          Circuits  related to each Backbone  Agreement and,  after  assignment,
          minimum revenue or volume commitments of WinStar,  if any,  associated
          with  the  Assumed  Backbone  Agreements  and  Renegotiated   Backbone
          Agreements.  In no event shall WinStar be responsible  for any minimum
          revenue or volume commitments under a Renegotiated  Backbone Agreement
          beyond such commitments agreed to by WinStar prior the Effective Date.
          Subject to WinStar's confidentiality obligations, WinStar will provide
          Williams  reasonable access to its records,  books and other documents
          and  data  related  to  each  Backbone  Agreement,   Assumed  Backbone
          Agreement  and  Renegotiated  Backbone  Agreement.  WinStar  will also
          cooperate  with  Williams in the  administration  of such  agreements.
          Williams is not  obligated to assume any Circuit until such Circuit is
          identified  by  the  parties.  

     (f)  WinStar  Disputes.  Williams  will  endeavor to resolve,  on behalf of
          WinStar and at  WinStar's  expense,  any  back-billing  dispute  which
          accrued prior to the applicable  Assignment  Agreement  Effective Date
          (provided  that  notice of any such  dispute is  received  by Williams
          before any such Assignment  Agreement Effective Date) and WinStar will
          cooperate  fully in any such  effort.  

     (g)  Orders Under  Assumed and  Renegotiated  Backbone  Agreements.  Unless
          otherwise  permitted  by  Williams,  WinStar  will place  orders under
          Assumed  Backbone  Agreements  and  Renegotiated  Backbone  Agreements
          through Williams. Williams will not be obligated to accept any Circuit
          arranged  by  WinStar  in  contravention  of this  provision  and such
          Circuit  will not become  subject  to the  Assignment  and  Assumption
          Agreement unless  otherwise agreed to by Williams,  such agreement not
          to be unreasonably withheld.
          

     (h)  Relationship  to the Minimum  Commitment and  Migration.  Provision of
          service under any Backbone  Agreement  (including the Assumed Backbone
          Agreements and Renegotiated Backbone Agreements) will not count toward
          satisfaction  of the  Minimum  Commitment  until  such  time  as  such
          Circuits are migrated onto the Williams Network.  Subject to WinStar's
          prior  approval in each  instance,  Williams  shall  migrate  Circuits
          provided  under  any  Assumed  Backbone   Agreements  or  Renegotiated
          Backbone  Agreements  as  soon as  reasonably  possible,  taking  into
          account any Circuit terms,  early  termination  fees or Minimums.  

     (i)  Assumption  Proviso.  Williams  shall not be  obligated  to assume any
          Backbone  Agreement  that  would  materially   conflict  with  another
          Williams contract,  have a materially  adverse effect on Williams,  or
          that contains any material usage commitment based upon a percentage of
          WinStar's  telecommunications  needs.  In the event  Williams does not
          assume such Backbone  Agreement,  Williams will act as a payment agent
          as  provided  in  Section  5.4(c).  

                                       16

<PAGE>

6.  CONNECTION  TO THE  SYSTEM AND COLLOCATION 

     6.1. Collocation.

     (a)  WinStar shall have the right to use Transmission Sites along the Route
          pursuant to the Fiber Collocation Provisions.  Such Transmission Sites
          shall meet or exceed the power and building requirements  specified in
          Exhibit G. WinStar shall  provide,  maintain,  and for all purposes be
          solely  responsible for all WinStar Equipment at Transmission Sites or
          other locations.


     (b)  Collocations  in  Williams  Points of  Presence  will be  provided  in
          accordance with the terms contained in Exhibit C, Part 2.

     (c)  Subject to the terms of Section 24.1(l), if, after the Acceptance Date
          for  any  System  Segment,  Williams  is in  material  breach  of  its
          obligation  to provide the rack space or square  footage  specified by
          the  Collocation   Provisions  at  any  Transmission  Site  (excluding
          Transmission Sites on the Dallas-Houston  System Segment) for a period
          of more than one hundred twenty (120)  consecutive  days after WinStar
          provides  written  notice  of such  breach,  WinStar  may  deduct  the
          following  amount  from its  monthly  invoice,  pro-rated  for partial
          months,  so long as that  material  breach  continues  beyond such one
          hundred twenty (120) day period:  (i) Five Thousand  Dollars  ($5,000)
          per month prior to the eighth  anniversary of the relevant  Acceptance
          Date, (ii) one thousand dollars ($1,000) per month from the the eighth
          anniversary  of the relevant  Acceptance  Date up to but not including
          the tenth anniversary of the relevant  Acceptance Date, and (iii) five
          hundred dollars ($500) per month thereafter.  The preceding  provision
          shall  apply  on a  per-Transmission  Site  basis  for  each  relevant
          Transmission Site. 

     6.2. Interconnection.

     (a)  With respect to each of the cities served by the WinStar  Fibers,  the
          parties  shall  mutually   determine  the  most  efficient  manner  of
          providing the required  connectivity  ("Interconnection")  between the
          WinStar and Williams points of presence, whether through then-existing
          installed  capacity,  implementation  of new  capacity  or third party
          arrangements.  In  addition,  the parties  shall set and  periodically
          review the schedule (timing and priority) of  implementation  of those
          Interconnection  facilities  and  shall  adhere  to that  schedule  in
          implementing such facilities.

                                       17
<PAGE>


     (b)  The parties shall allocate the costs of each Interconnection  facility
          as follows:

          (i)  The parties shall  mutually agree upon a forecast of each party's
               usage of that  Interconnection  facility  during  the first  year
               after  implementation  (the "Forecast").  The non-recurring costs
               associated  with  the  implementation  of that  facility  and the
               recurring  cost  thereof  in the  first  month of  operation  (in
               aggregate,  the  "Start-up  Costs")  will be  allocated  pro rata
               between the parties based upon the Forecast.  One year thereafter
               the parties  shall  re-calculate  the  allocation of the Start-up
               Costs by  substituting  actual usage during the preceding year in
               place of the Forecast.  Based upon that  recalculation,  Williams
               shall  pay or  receive  a refund,  in  either  case  equal to the
               difference  between the initial  allocation of the Start-up Costs
               and the recalculated  amount, plus interest at the Prime Rate for
               the applicable period.

          (ii) On a quarterly  basis,  the parties  shall  allocate the periodic
               recurring costs of that Interconnection facility pro rata between
               the parties based upon actual usage during the preceding quarter.

          (iii)Following the Effective  Date, the parties will mutually  develop
               appropriate procedures to implement the foregoing. 

     6.3. Ancillary Services.

          Williams  may also  provide  other  services  to WinStar  for  reasons
          including,  but not  limited  to: (a)  WinStar's  request to  expedite
          Telecommunications  Services  availability  to  a  date  earlier  than
          Williams'  published  installation  interval or a previously  accepted
          Start Date; (b) Telecommunications Services redesign or other activity
          occasioned by receipt of  inaccurate  information  from  WinStar;  (c)
          WinStar's  request  for use of routes or  facilities  other than those
          selected by Williams for provision of the Telecommunications Services;
          and (d) other  circumstances in which extraordinary costs and expenses
          are  generated  at the  written  request of WinStar  and  incurred  by
          Williams  (collectively,  "Ancillary  Services").  

7.  ACCEPTANCE  AND TESTING OF FIBERS 

     7.1. Overview.

          Fiber Acceptance  Testing of the WinStar Fibers shall be conducted for
          each System Segment Portion  ("System Segment Portion Fiber Acceptance
          Testing" or  "SSPFAT").  The  provisions  set forth below  address the
          acceptance   procedures  and  provisions  regarding  failure  notices,
          corrections,  third party  testing  and testing of the Option  Fibers.



                                       18

<PAGE>

     7.2. SSPFAT by Williams.

          Williams shall perform SSPFAT of the WinStar Fibers in accordance with
          Exhibit D. SSPFAT  shall  progress  System  Segment  Portion by System
          Segment  Portion  along  the  Route of each  System  Segment  as cable
          splicing progresses,  so that test results may be reviewed in a timely
          manner. WinStar shall have the right, but not the obligation,  to have
          an individual  present to observe  Williams'  SSPFAT or to conduct its
          own SSPFAT in  accordance  with Section 7.3 below  (except,  in either
          case, to the extent  Williams' System Segment Portion Fiber Acceptance
          Testing  takes place prior to the period ending twenty (20) days after
          the Effective Date).  Williams shall provide WinStar at least ten (10)
          days prior notice of Williams' testing schedule or any change thereto.
          Within  twenty  (20) days  after the  conclusion  of any SSPFAT of the
          WinStar  Fibers  conducted  by  Williams in any given  System  Segment
          Portion,  Williams  shall  provide  WinStar  with a copy  of the  test
          results  provided  that in no case  shall  Williams  be  obligated  to
          provide  copies of such test results  before  January 11,  1999.  

     7.3. SSPFAT by WinStar.

          WinStar  shall have the  right,  but not the  obligation,  at its sole
          expense,  to conduct  its own SSPFAT of the  WinStar  Fibers to verify
          that they meet the Acceptance Standards.  If WinStar elects to conduct
          its own SSPFAT of the WinStar Fibers,  it shall notify Williams of its
          intent to do so  (including  dates and  locations)  at least three (3)
          days  prior to the date of  Williams'  scheduled  commencement  of the
          SSPFAT  of  a  particular  System  Segment  Portion  as  specified  in
          Williams'  ten day prior  written  notice to  WinStar as  provided  in
          Section  7.2.  WinStar  may elect to perform  such  testing (i) itself
          subsequent to the Williams testing or (ii) concurrently with Williams'
          testing  (except to the extent  Williams'  testing take place prior to
          the period ending twenty (20) days after the Effective Date), in which
          case  both  parties  shall  reasonably  cooperate  with  the  other to
          facilitate such concurrent  testing.  If WinStar elects to perform the
          testing itself subsequent to Williams' testing,  WinStar will complete
          such testing within ten (10) days after Williams  completes its SSPFAT
          of the  relevant  System  Segment  Portion  (except to the extent such
          Williams  testing  takes place prior to the period  ending twenty (20)
          days after the  Effective  Date in which case WinStar  shall  complete
          such SSPFAT by January 25, 1999).  Williams shall have the right,  but
          not the obligation, to have an individual present to observe WinStar's
          SSPFAT.  Within  twenty (20) days after the  conclusion  of  WinStar's
          SSPFAT of the WinStar  Fibers,  WinStar shall provide  Williams with a
          copy of the test results.  WinStar's  exercise or  non-exercise of its
          right to conduct  SSPFAT  shall not extend or shorten the time periods
          for  WinStar to  determine,  pursuant  to Section  7.4,  if the System
          Segment  Portion  meets  the  Acceptance  Standards.   Williams  shall
          reasonably  cooperate  with WinStar to facilitate  SSPFAT.  Changes in
          testing  schedules  may be mutually  agreed upon by the Parties.  

                                       19
<PAGE>

     7.4. Failure Notice.

          If,  within  fourteen  (14) days  after the  later of (i)  receipt  by
          WinStar from  Williams of the test results  referred to in Section 7.2
          or of the results of  re-testing  as set forth below and (ii)  WinStar
          conclusion  of its own  testing as provided  in Section  7.3,  WinStar
          reasonably  determines  that  Williams' or WinStar's test results show
          that the System Segment  Portion of the WinStar Fibers do not meet the
          Acceptance  Standards,  WinStar  shall,  within such fourteen (14) day
          period,  notify Williams of such  determination  and shall identify in
          writing  the  specific  data that  indicate  such  failure to meet the
          Acceptance Standards.  Notwithstanding the foregoing,  if the fourteen
          (14) day period ends prior to January 25, 1999 for any System  Segment
          Portion,  WinStar  will have until  January 25, 1999 to give  Williams
          notice  of  failures  of  the  System  Segment  Portion  to  meet  the
          Acceptance Standard. 

     7.5. Correction.

     (a)  Upon  receiving  notice  pursuant to Section 7.4 that a System Segment
          Portion of the WinStar  Fibers do not meet the  Acceptance  Standards,
          Williams  shall  either:   

          (i)  Expeditiously  take such action as reasonably  necessary to cause
               such System Segment Portion to meet the Acceptance  Standards and
               then re-test in accordance  with the  provisions of this Article;
               or  

          (ii) Notify  WinStar that Williams  disputes  WinStar's  determination
               that the System Segment Portion of the WinStar Fibers do not meet
               the Acceptance Standards. 

     (b)  After taking corrective  actions and re-testing the WinStar Fibers (if
          appropriate),  Williams  shall provide  WinStar with a copy of the new
          test results and WinStar shall again have all rights  provided in this
          Article with  respect to such new test  results.  The cycle  described
          above of testing,  taking  corrective action and re-testing shall take
          place  until  the  WinStar  Fibers  meet  the  Acceptance   Standards;
          provided,  however,  repeating  this  cycle  shall  not in any  manner
          whatsoever limit any other right or remedy WinStar may have under this
          Agreement. 

     7.6. Testing by Third Party.

          If  Williams   provides  notice  to  WinStar  pursuant  to  Subsection
          7.5(a)(ii),  and the parties are unable to otherwise  mutually  agree,
          the parties  shall appoint a mutually  acceptable  fiber optic testing
          company and such company shall re-test the  applicable  System Segment
          Portion of the  WinStar  Fibers.  If that test  demonstrates  that the
          tested  System  Segment   Portion  of  the  WinStar  Fibers  meet  the
          Acceptance  Standards  without any changes to such portion by Williams
          as tested by WinStar,  then  WinStar  shall pay the testing  company's
          charges  and shall be  deemed to have  accepted  the  relevant  System
          Segment Portion of the WinStar Fibers.  If that test demonstrates that
          the relevant  System Segment Portion of the WinStar Fibers do not meet
          the Acceptance Standards or that they do meet the Acceptance Standards
          due  to  changes  made  by  Williams  following  WinStar's  acceptance
          testing,  then Williams  shall pay the testing  company's  charges for
          performing  the testing and shall  perform the  corrective  action and
          re-testing  set forth in Subsection  7.5(a)(i).  

                                       20
<PAGE>

     7.7.  System  Segment Fiber Acceptance Testing and Acceptance Date.

          If the Fiber  Acceptance  Testing for all System Segment Portions of a
          System  Segment  shows that the  WinStar  Fibers  meet the  Acceptance
          Standards  and WinStar does not object to the results of any SSPFAT by
          written  notice  within the time  periods  specified  in Section  7.4,
          WinStar  shall  be  deemed  to have  accepted  the  particular  System
          Segment.  The date of WinStar's notice accepting the System Segment of
          the WinStar Fibers or the date of deemed acceptance under this Article
          for the  last  of all of the  System  Segment  Portions  for a  System
          Segment to be accepted shall be the  "Acceptance  Date" of the WinStar
          Fibers for that System  Segment.  The provisions of this Section shall
          not be deemed to relieve Williams of its obligation to provide Routine
          Maintenance or non-Routine Maintenance as set forth in this Agreement.

     7.8. Testing of Option Fibers.

          Williams  shall include the Option Fibers in the SSPFAT of each System
          Segment. Upon WinStar's exercise of the Option, Williams shall provide
          copies  of  the  results  of all  SSPFAT  of the  Option  Fibers.  The
          provisions  above shall be  applicable to the Option Fibers if WinStar
          exercises its Option.

8.       USE OF THE SYSTEM

     8.1. Use of WinStar Fibers.

          WinStar may use the WinStar Fibers for any lawful purpose.

     8.2. Notice of Damage.

          WinStar shall promptly  notify  Williams of any matters  pertaining to
          any damage or impending  damage to or loss of System that are actually
          known to it and that could  reasonably be expected to adversely affect
          the System.

     8.3. Precautions.

          WinStar  shall  take all  reasonable  precautions  against  any damage
          proximately caused by WinStar to the System or to fibers used or owned
          by Williams or third parties.

     8.4. Use of Equipment.

          Neither   party  shall  use,  or  allow  others  to  use,   equipment,
          technologies,  or  methods  of  operation  that  adversely  affect the
          Williams  Network or the System or the  permitted  use of the Williams
          Network or the System by Williams or third parties or their respective
          Fibers, equipment, or facilities associated therewith. If WinStar uses
          equipment,   technologies,   and   methods  of   operation   that  are
          collectively  either in accord with  Williams'  practices or generally
          accepted  industry  standards,  Williams  shall  have  the  burden  of
          demonstrating  that  WinStar  has  breached  the  requirements  of the
          preceding sentence. 

                                       21

<PAGE>

     8.5. Liens.

          WinStar  shall  not,  directly  or  indirectly,  cause any part of the
          System to become subject to any mechanic's lien,  materialman's  lien,
          vendor's  lien,  or any similar  lien  whether by  operation of law or
          otherwise.   If  WinStar  becomes  aware  that  it  has  breached  its
          obligations under this Section, it shall promptly:  notify Williams in
          writing,  cause  such lien to be  discharged  and  released  of record
          without cost to Williams and indemnify  Williams against all costs and
          expenses  (including  reasonable  attorneys'  fees and court  costs at
          trial and on appeal) incurred in discharging and releasing such lien.

9.       TERM

     9.1. Agreement Term.

          The term of this  Agreement  (the "Term") shall begin on the Effective
          Date and shall  end upon  expiration  of the last IRU Term to  expire,
          provided that,  with respect to the Interim IRU, the Term shall extend
          twenty-five years from the Effective Date.

     9.2. IRU Terms.

          The term of this Agreement in respect of each System Segment (the "IRU
          Term") shall begin on the applicable  Acceptance Date and shall end on
          the twenty-fifth (25th) anniversary of such Acceptance Date.

     9.3. Effect of Termination.

          No termination of this  Agreement,  an IRU Term, or of the Interim IRU
          shall affect the rights or obligations of any party hereto:

     (a)  With respect to any payment hereunder for services rendered during the
          Term; or

     (b)  Pursuant  to  Articles  14, 15,  16, 17, 18, 20, 23 and 24.1  entitled
          Audit Rights;  Indemnification;  Limitation  of Liability;  Insurance;
          Taxes and  Governmental  Fees;  Confidentiality;  Remedies and Dispute
          Resolution;  and Rules of Construction,  respectively.  

                                       22
<PAGE>

10. OPERATION, MAINTENANCE, AND REPAIR OF THE SYSTEM 

     10.1. Routine Maintenance.

          During the IRU Term,  Williams  shall  perform  all  required  Routine
          Maintenance at no additional  cost to WinStar.  "Routine  Maintenance"
          means the work  specifically  identified  as  Routine  Maintenance  in
          Exhibit I, provided that Routine  Maintenance  excludes work for which
          WinStar is obligated to reimburse Williams for all or a portion of the
          Costs incurred pursuant to other Articles of this Agreement (including
          the Fiber Collocation Provisions). 

     10.2. Non-Routine Maintenance.

          WinStar  shall pay its  Pro-Rata  Share of  Williams'  direct Costs of
          non-Routine  Maintenance  of the  System,  if the  Cost of  such  work
          relating  to any single  event or multiple  related  events is greater
          than five thousand dollars ($5,000.00). 

     10.3. Subcontractors.

          Williams may subcontract provisioning,  testing, maintenance,  repair,
          restoration,  relocation,  or other operational and technical services
          it is  obligated  to  provide  hereunder  or may have  the  underlying
          facility  owner  or its  contractor  perform  such  obligations.  Such
          subcontracting  shall not relieve  Williams of any  obligations  under
          this  Agreement.   

     10.4. Continued  Breach  of  Routine  Maintenance Obligations.

          Subject to the terms of Section 24.1(l), if, after the Acceptance Date
          for  any  System  Segment,  Williams  is in  material  breach  of  its
          obligation to provide  Routine  Maintenance  for a period of more than
          one hundred  twenty  (120)  consecutive  days after  WinStar  provides
          written notice of such breach, WinStar may deduct the following amount
          per month,  pro-rated for partial months, per each relevant Route mile
          from its monthly  invoice so long as that  material  breach  continues
          beyond such one hundred twenty (120) day period:  (i) seventy  dollars
          ($70)  per  month  prior to the  eighth  anniversary  of the  relevant
          Acceptance  Date,  (ii) ten  dollars  ($10) per month  from the eighth
          anniversary  of the relevant  Acceptance  Date up to but not including
          the tenth anniversary of the relevant  Acceptance Date, and (iii) five
          dollars ($5) per month thereafter. 

     10.5. WinStar Equipment.

          Williams'  maintenance  and repair  obligations  under this  Agreement
          shall not  include  maintenance,  repair  or  replacement  of  WinStar
          Equipment.

     10.6 Access to Systems.

          WinStar  shall not access  any  physical  part of any  System  Segment
          (other than pursuant to the Fiber Collocation  Provisions) without the
          prior  written  consent of Williams,  and then only upon the terms and
          conditions specified by Williams. 

                                       23

<PAGE>

11. RELOCATION 

     11.1. Relocation.

          If,  following the Acceptance  Date for any System  Segment,  Williams
          determines  for bona fide  operational  reasons,  or is  required by a
          third party acting pursuant to condemnation or similar authority or by
          a governmental  entity,  to relocate all or any portion of such System
          Segment or any of the facilities used or required in providing WinStar
          with the  WinStar  IRU,  Williams  shall,  to the extent  practicable,
          provide  WinStar sixty (60) days' prior notice of any such  relocation
          and shall proceed with such relocation.  Williams shall have the right
          to direct such relocation, including the right to determine the extent
          of,  the  timing  of,  and  methods  to be used for  such  relocation,
          provided that any such relocation:

          (a)  Shall  be   constructed   and  tested  in  accordance   with  the
               specifications  and  requirements set forth in this Agreement and
               applicable Exhibits;

          (b)  Shall  not  result  in  a  materially   adverse   change  to  the
               operations,  performance,  Connecting  Points with the network of
               WinStar, or end points of the System Segment; and

          (c)  Shall not unreasonably interrupt service on the System Segment.

          For purposes of this Section, a Williams' relocation shall be for bona
          fide  operational  reasons  if it is  undertaken  in good faith (i) to
          settle or avoid a bona fide threatened or filed condemnation action or
          order by a  governmental  authority  to  relocate,  (ii) to reduce the
          likelihood of physical damage to the System,  (iii) as the result of a
          Force Majeure Event,  or (iv) for other  operational  reasons to which
          WinStar has  consented,  provided that WinStar shall not  unreasonably
          withhold  such  consent.  Williams  shall use  reasonable  efforts  to
          contest any exercise of  condemnation  authority  that would require a
          relocation that would require WinStar to reimburse  Williams  pursuant
          to this Article 11.

     11.2. Cost of Relocation.

          Unless  such  relocation  is  necessitated  by a breach  of  Williams'
          obligations under this Agreement,  any Costs Williams incurs shall not
          be Routine Maintenance Costs, and WinStar shall reimburse Williams for
          the Costs incurred in the same manner and to the same extent as is set
          forth for  reimbursement of non-Routine  Maintenance  Costs in Section
          10.2. 

     11.3. Updated As-Built Drawings.

          At  WinStar's  written  request,  Williams  shall  deliver  to WinStar
          updated as-built  drawings with respect to a relocated  portion of the
          System  Segment  within  the later of  one-hundred  eighty  (180) days
          following the completion of such  relocation or thirty (30) days after
          receipt of WinStar's request. 

                                       24
<PAGE>

12. INVOICING AND PAYMENT 

     12.1. Due Date and Invoice.

          (a)  Payments of the Contract  Price and Exercise  Price shall be made
               in accordance with the Payment Terms.

          (b)  All amounts  stated on each  monthly  invoice are due and payable
               thirty  (30) days from  WinStar's  receipt of the  invoice  ("Due
               Date").  WinStar  agrees  to remit  payment  to  Williams  at the
               remittance  address set forth in the  applicable  invoice.  

     12.2. Form of Payment.

          WinStar  shall  pay the  Contract  Price  and  Exercise  Price by wire
          transfer of immediately  available  funds to the United States account
          or accounts  designated  by  Williams.  All other  payments to be made
          pursuant  to  this  Agreement  may  be  made  by  check  or  draft  of
          immediately  available  funds  delivered to the address  designated in
          writing by the other  party  (e.g.,  in a statement  or  invoice)  or,
          failing  such  designation,  to the  address  for notice to such other
          party provided pursuant to Article 19. 

     12.3. Disputed Charges.

          (a)  WinStar shall pay  undisputed  charges when such payments are due
               under this Agreement.  WinStar may withhold payment of particular
               charges  that  WinStar  disputes  in good  faith and for which it
               promptly gives written notice to Williams, stating the details of
               such  dispute.  The parties shall  promptly  refer such matter to
               dispute  resolution  in  accordance  with  Section 23. If WinStar
               withholds  any disputed  charges and such charges are  ultimately
               determined  to be proper and payable to Williams,  WinStar  shall
               pay such charges to Williams plus interest at the Prime Rate from
               the date such  charges  were  originally  due until the date such
               charges  are  paid.  No  payment  dispute  shall be  grounds  for
               Williams to  withhold or diminish  the quality or quantity of any
               of the connectivity and services provided hereunder.

          (b)  If WinStar  fails to pay  undisputed  charges  provided for under
               this  Agreement  when such  charges  are due,  Williams  may,  in
               addition  to any  other  remedies  that it may  have  under  this
               Agreement or by law,  terminate this Agreement only as it applies
               to the System Segment(s) or Telecommunications  Services to which
               such failure applies,  upon at least thirty (30) days' notice, if
               such  payment  (together  with  applicable  interest) is not made
               within such thirty (30) day notice  period  subject to  WinStar's
               thirty-day right to cure,  provided however,  that this remedy of
               termination  shall be available to Williams  only with respect to
               System  Segments for which the unpaid amount  exceeds two hundred
               thousand dollars ($200,000) at the time of such notice.

                                       25
<PAGE>

     12.4. Late Interest.

          If either  Williams or WinStar  fails to make any  payment  under this
          Agreement when due, such amounts shall accrue interest,  from the date
          such payment is due until paid,  including  accrued  interest,  at the
          Prime Rate. 

     12.5. Adjustments.

          Williams may make corrections to its invoices to reflect  undercharges
          only for the  period of two (2) years  following  the Due Date of each
          invoice, or two (2) years following the date the corresponding service
          is rendered,  whichever is later.  

13.  DISCLAIMER OF WARRANTIES 

     13.1. Parties.

          EXCEPT AS SPECIFICALLY  SET FORTH IN THIS AGREEMENT,  THE PARTIES MAKE
          NO  WARRANTY  TO EACH  OTHER OR ANY  OTHER  ENTITY,  WHETHER  EXPRESS,
          IMPLIED OR  STATUTORY,  AS TO THE  MERCHANTABILITY  OR FITNESS FOR ANY
          PARTICULAR PURPOSE OF ANY FIBERS,  THE SYSTEM, THE  TELECOMMUNICATIONS
          SERVICES,  ANY OTHER  SERVICES  OR ANY  ADDITIONAL  SERVICES  PROVIDED
          HEREUNDER OR DESCRIBED HEREIN, OR AS TO ANY OTHER MATTER, ALL OF WHICH
          WARRANTIES  ARE  HEREBY  EXPRESSLY  EXCLUDED  AND  DISCLAIMED.   

     13.2. Facility Owners/Lenders.

          NO FACILITY OWNERS/LENDERS HAVE MADE ANY REPRESENTATION OR WARRANTY OF
          ANY KIND,  EXPRESS OR IMPLIED,  TO WINSTAR  CONCERNING  WILLIAMS,  THE
          WINSTAR  FIBERS,  THE CABLE, OR THE SYSTEM OR AS TO ANY OF THE MATTERS
          SET FORTH IN SECTIONS  12.1 OR 24.2(a).  

14.  AUDIT  RIGHTS 

     Each party shall keep such books and records  (which shall be maintained on
     a consistent basis and substantially in accordance with generally  accepted
     accounting  principles) as shall readily disclose the basis for any charges
     (except  charges fixed in advance by this Agreement or by separate  written
     agreement of the parties) or credits, ordinary or extraordinary,  billed or
     due to the other party under this Agreement and shall make them  available,
     upon reasonable  notice and during normal working hours,  for  examination,
     audit,  and  reproduction by the other party and its agents for a period of
     one  (1)  year  after  such  charge  or  credit  is  billed  or  due.   

                                       26
<PAGE>

15. INDEMNIFICATION 

     15.1. Indemnification.

          Each party ("Indemnitor") shall indemnify,  defend,  protect, and hold
          harmless the other party, its employees,  members, managers, officers,
          agents,   contractors,   Facility   Owners/Lenders,   and   Affiliates
          (collectively and individually,  "Claimant"), from and against any and
          all Losses  resulting  or arising  from,  relating  to or  incurred in
          connection with:

          (a)  The  Indemnitor's  failure to  observe  or perform  its duties or
               obligations to third parties (e.g.,  duties or obligations to its
               customers);

          (b)  The Indemnitor's infringement or misappropriation of Intellectual
               Property Rights of any third party;

          (c)  The death or  bodily  injury of any  agent,  employee,  customer,
               business  invitee or any other person to the extent caused by the
               tortious conduct of the Indemnitor;

          (d)  The damage,  loss or destruction of any real or tangible personal
               property  to the  extent  caused by the  tortious  conduct of the
               Indemnitor;

          (e)  Fines, penalties or other amounts payable due to the Indemnitor's
               violation of applicable laws or regulation; and

          (f)  Any claim,  demand,  charge,  action,  cause of action,  or other
               proceeding  asserted  against the Claimant but resulting  from an
               act or omission of the  Indemnitor in its capacity as an employer
               of a person.

     15.2. Third Party Claims.

          With respect to third-party  claims,  the following  procedures  shall
          apply:  

          (a)  Promptly  after  receipt  of  notice  of  the   commencement   or
               threatened  commencement of any civil, criminal,  administrative,
               or  investigative  action  or  proceeding  involving  a claim  in
               respect of which the Claimant will seek indemnification  pursuant
               to this Article 15, the Claimant  will notify the  Indemnitor  of
               such claim in  writing.  No  failure to so notify the  Indemnitor
               will  relieve  the  Indemnitor  of  its  obligations  under  this
               Agreement  except to the extent  that its  ability to defend such
               claim is materially  prejudiced by such failure.  Within  fifteen
               (15) calendar days  following  receipt of written notice from the
               Claimant  relating  to any  claim,  but no  later  than  ten (10)
               calendar  days  before  the  date  on  which  any  response  to a
               complaint  or  summons is due,  the  Indemnitor  will  notify the
               Claimant in writing if the Indemnitor elects to assume control of
               the  defense  and   settlement   of  that  claim  (a  "Notice  of
               Election").

          (b)  If the Indemnitor  delivers a Notice of Election  relating to any
               claim within the required notice period,  the Indemnitor shall be
               entitled to have sole control over the defense and  settlement of
               such claim;  provided that (i) the Claimant  shall be entitled to
               observe  the  defense of such claim and to employ  counsel at its
               own expense to observe  the  defense of such claim,  and (ii) the
               Indemnitor  shall obtain the prior  written  approval,  not to be
               unreasonably  withheld or delayed, of the Claimant before ceasing
               to defend  against such claim or entering into any  settlement of
               such  claim.  After  the  Indemnitor  has  delivered  a Notice of
               Election  relating to any claim in accordance  with the preceding
               paragraph, the Indemnitor shall not be liable to the Claimant for
               any legal  expenses  incurred by the Claimant in connection  with
               the defense of that claim. In addition,  the Indemnitor shall not
               be  required to  indemnify  the  Claimant  for any amount paid or
               payable by the Claimant in the  settlement of any claim for which
               the  Indemnitor has delivered a timely Notice of Election if such
               amount  was  agreed  to  without  the  written   consent  of  the
               Indemnitor.

                                       27
<PAGE>

          (c)  If the Indemnitor does not deliver a Notice of Election  relating
               to  any  claim  within  the  required   notice  period  or  after
               delivering  a Notice of Election  fails to defend the claim,  the
               Claimant  shall have the right to defend the claim in such manner
               as  it  may  deem  appropriate.  The  Indemnitor  shall  promptly
               reimburse the Claimant for all  reasonable  costs and expenses of
               such defense. 

     15.3. Indemnification of Providers.

          WinStar shall indemnify and hold harmless Williams and any Third Party
          Service  Providers  from and  against  all  Losses  arising  out of or
          relating to the  content of any  transmission  by  WinStar,  including
          claims  relating  to any  violation  or  alleged  violation  of export
          control  laws or  other  laws or  failure  to  comply  with  WinStar's
          obligations as set forth in Sections 26.4 and 26.5.

15.4.    WinStar Customers.

          WinStar shall  indemnify  and hold Williams  harmless from and against
          all Losses arising out of or relating to the use of the WinStar Fibers
          by any WinStar customer.

16.  LIMITATION OF LIABILITY

     16.1. General Intent.

          Subject  to the  specific  provisions  of this  Article  16, it is the
          intent of the  Parties  that each  party  shall be liable to the other
          party for any actual damages incurred by the non-breaching  party as a
          result of the breaching  party's failure to perform its obligations in
          the manner required by this Agreement.

     16.2. Liability Restrictions.

          (a)  IN NO EVENT,  WHETHER IN CONTRACT OR IN TORT (INCLUDING BREACH OF
               WARRANTY, NEGLIGENCE AND STRICT LIABILITY IN TORT), SHALL A PARTY
               BE LIABLE FOR INDIRECT OR CONSEQUENTIAL,  EXEMPLARY,  PUNITIVE OR
               SPECIAL  DAMAGES  EVEN IF SUCH  PARTY  HAS  BEEN  ADVISED  OF THE
               POSSIBILITY OF SUCH DAMAGES IN ADVANCE.

                                       28
<PAGE>

          (b)  Subject to Subsection (c), below, each party's total liability to
               the other,  whether in contract or in tort  (including  breach of
               warranty,  negligence  and  strict  liability  in tort)  shall be
               limited to two hundred million dollars ($200,000,000).

          (c)  The  limitation set forth in Subsections  (b),  above,  shall not
               apply  with  respect  to:  (i)  third-party   claims  subject  to
               indemnification  pursuant  to the  Agreement;  (ii)  fees due and
               owing under this  Agreement  at the time of the claim;  and (iii)
               amounts subject of Cover as provided in Section 4.2(b).

          (d)  For the purposes of this  Section  16.2,  all amounts  payable or
               paid to third parties in connection with claims that are eligible
               for  indemnification  pursuant to this Agreement  shall be deemed
               direct damages.


     16.3. Released Parties.

          Neither party shall have any recourse of any kind against any Released
          Party or any assets of a  Released  Party in respect of any Claim that
          is not directly or indirectly  caused by the Released  Party, it being
          expressly  agreed and understood  that no liability  whatsoever  shall
          attach to or be incurred by any Released Party in respect of any Claim
          under  or by  reason  of  this  Agreement  or  any  other  instrument,
          arrangement or understanding  relating to the Network IRU, the System,
          the Interim IRU, the  Telecommunications  Services, the Other Services
          or Additional Services, except to the extent such Claim is directly or
          indirectly  caused by the Released  Party.  Each party waives all such
          recourse  to the  extent  set forth in this  Section  on behalf of its
          successors,  assigns,  and any entity claiming by,  through,  or under
          such party.

17.      INSURANCE

     17.1. Insurance.

          During the Term,  the parties  shall each obtain and maintain not less
          than the following insurance:

          (a)  Commercial  General Liability  Insurance,  including coverage for
               sudden and accidental pollution legal liability,  with a combined
               single limit of $10,000,000 for bodily injury and property damage
               per occurrence and in the aggregate.

          (b)  Worker's Compensation Insurance in amounts required by applicable
               law and Employers  Liability  Insurance with limits not less than
               $1,000,000  each accident.  If work is to be performed in Nevada,
               North Dakota,  Ohio,  Washington,  Wyoming or West Virginia,  the
               party shall participate in the appropriate state fund(s) to cover
               all eligible employees and provide a stop gap endorsement.

                                       29
<PAGE>

          (c)  Automobile  Liability  Insurance with a combined  single limit of
               $2,000,000 for bodily injury and property  damage per occurrence,
               to include coverage for all owned, non-owned, and hired vehicles.
          
     The limits set forth above are minimum limits and shall not be construed to
     limit the liability of either party.

     17.2. Documentation.

          (a)  Each party  shall  obtain and  maintain  the  insurance  policies
               required  above with  companies  rated A- or better by Best's Key
               Rating  Guide  or with a  similar  rating  by  another  generally
               recognized  rating  agency.  The  other  party,  its  Affiliates,
               officers,  directors, and employees, and any other party entitled
               to  indemnification   hereunder  shall  be  named  as  additional
               insureds to the extent of such indemnification.  Each party shall
               provide the other party with an insurance certificate  confirming
               compliance with the insurance  requirements of this Article.  The
               insurance  certificate  shall indicate that the other party shall
               be  notified  not  less  than  thirty  (30)  days  prior  to  any
               cancellation or material change in coverage.

          (b)  If either party provides any of the foregoing coverages through a
               claims made policy  basis,  that party shall cause such policy or
               policies to be maintained for at least three (3) years beyond the
               expiration of this Agreement.

     17.3. Certificates.

          The parties shall each obtain from the insurance  companies  providing
          the  coverages  required  by this  Agreement a waiver of all rights of
          subrogation   or  recovery  in  favor  of  the  other  party  and,  as
          applicable,   its   members,   managers,   shareholders,   Affiliates,
          assignees,  officers,  directors,  and  employees  or any other  party
          entitled  to  indemnity  under  this  Agreement  to the extent of such
          indemnity.

     17.4. Blanket Policies.

          Nothing in this  Agreement  shall be construed to prevent either party
          from satisfying its insurance  obligations  pursuant to this Agreement
          under a blanket  policy or policies of  insurance  that meet or exceed
          the requirements of this Article.

18.      TAXES AND GOVERNMENTAL FEES

     18.1. Payment by WinStar.

          WinStar  shall timely report and pay any and all sales,  use,  income,
          gross receipts,  excise, transfer, ad valorem, or other taxes, and any
          and all franchise  fees or similar fees, if any,  assessed  against it
          due to its  ownership  of the  Network  IRU,  its  use of the  WinStar
          Fibers,  including the provision of services over the WinStar  Fibers,
          its use of any other part of the System,  or its  ownership  or use of
          facilities connected to the WinStar Fibers.

                                       30
<PAGE>


     18.2. Payment by Williams.

          Subject to Section 18.1 above,  Williams  shall timely  report and pay
          any and all sales, use, income, gross receipts,  excise,  transfer, ad
          valorem or other taxes, and any and all franchise fees or similar fees
          assessed against it due to its  construction,  ownership or use of the
          System,  provided  that  WinStar  shall  reimburse  Williams  for  its
          Pro-Rata Share of property taxes (including ad valorem, use, property,
          or similar taxes, franchise fees, or assessments that are based on the
          value of property or of a property right)  attributable to the System,
          including  taxes based on the value,  operation,  or  existence of the
          System.

     18.3. Reimbursement.

          If Williams is assessed for any taxes or fees (a) related to WinStar's
          ownership  of the  Network  IRU,  WinStar's  use of or  rights  in the
          WinStar  Fibers,  or (b) that  WinStar is obligated to pay pursuant to
          Sections  18.1 or  18.2,  WinStar  shall  reimburse  Williams  for any
          payment of such taxes or fees  within  thirty  (30) days of receipt of
          Williams' invoice.

     18.4. Cooperation.

          The parties shall  cooperate in any contest of any taxes or fees so as
          to avoid, to the extent reasonably possible, prejudicing the interests
          of the other party.

     18.5. Services.

          If  any  sales  taxes,  valued  added  taxes  or  similar  charges  or
          impositions  are assessed  against  Williams after, or as a result of,
          WinStar's use of  Telecommunications  Services,  any Other Services or
          the Additional Services by any local, state, national,  international,
          public or quasi-public  governmental  entity or foreign  government or
          its  political  subdivision,  including  any tax or  charge  levied to
          support   the   Universal    Service   Fund    contemplated   by   the
          Telecommunications  Act of 1996,  WinStar shall be solely  responsible
          for and shall pay such taxes, charges or impositions and hold Williams
          harmless  from any  liability or expense  associated  with such taxes,
          charges or impositions.

19.  NOTICE

     Unless otherwise provided in this Agreement, all notices and communications
     concerning  this  Agreement  shall be in writing and addressed to the other
     party as follows,  or at such other address as may be designated in writing
     to the other party:


         If to WinStar:                      If to Williams:
               WinStar Wireless, Inc.           Williams Communications, Inc.
               230 Park Avenue                  One Williams Center, Suite 26-5
               New York, NY  10169              Tulsa, Oklahoma  74172
               Attn:  EVP, General Counsel      Attn:  Contract Administration
               Facsimile:  212/922-1637         Facsimile:  918/573-6578

                                       31
<PAGE>

         With a copy to:                     With a copy to:
            WinStar Wireless, Inc.              Williams Communications, Inc.
            7799 Leesburg Pike                  One Williams Center, Suite 4100
            Falls Church, Virginia 22043        Tulsa, Oklahoma  74172
            Attn:  VP, Commercial and           Attn:  General Counsel
               Legal Operations               
            Facsimile:  703/288-6647            Facsimile:  918/573-3005

          Unless  otherwise  provided  herein,  notices shall be hand delivered,
          sent by registered or certified  U.S.  Mail,  postage  prepaid,  or by
          commercial  overnight  delivery service,  or transmitted by facsimile,
          and shall be deemed served or delivered to the addressee or its office
          when  received  at the address  for notice  specified  above when hand
          delivered, upon confirmation of sending when sent by facsimile, on the
          day after being sent when sent by overnight  delivery  service,  three
          (3) days after  deposit in the mail when sent by U.S.  mail or, in the
          case  of   invoices,   upon   the  Due  Date   (as   defined   in  the
          Telecommunications Services Purchase Provision).

20.  CONFIDENTIALITY

     20.1. Confidential Information.

          Williams and WinStar each acknowledge that they may be furnished with,
          receive,  or otherwise have access to information of or concerning the
          other party that such party considers to be confidential, proprietary,
          a trade secret or otherwise restricted.  As used in this Agreement and
          subject  to  Section  20.3,   "Confidential   Information"  means  all
          information,  in any form,  furnished  or made  available  directly or
          indirectly  by one party  (the  "Disclosing  Party") to the other (the
          "Receiving  Party")  that (i)  concerns  the  operations,  facilities,
          plans,  affairs and businesses of the Disclosing  Party, the financial
          affairs of the Disclosing  Party,  and the relations of the Disclosing
          Party with its customers,  employees and service providers, or (ii) is
          marked  confidential,  restricted,  proprietary,  or  with  a  similar
          designation.  The  terms and  conditions  of this  Agreement  shall be
          deemed  Confidential  Information,  but may be  disclosed  as provided
          below and Section 24.6.

     20.2. Obligations.

          (a)  Each party's  Confidential  Information shall remain the property
               of that party except as expressly provided otherwise by the other
               provisions of this Agreement.  Each party shall each use at least
               the  same  degree  of  care,  but in any  event  no  less  than a
               reasonable degree of care, to prevent unauthorized  disclosure of
               Confidential  Information  as it  employs  to avoid  unauthorized
               disclosure of its own information of a similar nature.  Except as
               otherwise  permitted  hereunder,  the parties may  disclose  such
               information  (A)  to  their   respective   directors,   officers,
               managers,   employees,   agents,   contractors   and  consultants
               (collectively,  "Representatives")  and (B)  entities  performing
               services required hereunder only where: (i) use of such entity is
               authorized   under  this  Agreement,   (ii)  such  disclosure  is
               necessary or otherwise naturally occurs in that entity's scope of
               responsibility,  and (iii) the entity agrees in writing to assume
               the obligations described in this Section 20.2. Any disclosure to
               such entity shall be under substantially the same confidentiality
               terms and conditions as provided herein.

                                       32
<PAGE>

          (b)  Each party  shall take  reasonable  steps to ensure that its (and
               its Affiliates')  Representatives  comply with this Section 20.2.
               In the  event of any  disclosure  or loss  of,  or  inability  to
               account  for,  any  Confidential  Information  of the  Disclosing
               Party,  the Receiving Party shall  promptly,  at its own expense:
               (i)  notify  the  Disclosing  Party in  writing;  (ii)  take such
               actions  as may be  necessary  and  cooperate  in all  reasonable
               respects with the Disclosing  Party to minimize the violation and
               any damage resulting therefrom.

          (c)  Either  party  may  disclose  the terms  and  conditions  of this
               Agreement  to any third party that (i) has  expressed a bona fide
               interest  in  consummating  a  significant  financing,  merger or
               acquisition  transaction or other corporate  transaction  between
               the third party and such  party,  (ii) has a  reasonable  ability
               (financial  or otherwise) to  consummate  such  transaction,  and
               (iii) has executed a nondisclosure agreement that includes within
               its scope the terms and  conditions  of this  Agreement  and also
               includes  a  procedure   to  limit  the  extent  of  copying  and
               distribution  thereof.  Each party  shall  endeavor  to delay the
               disclosure of the terms and  conditions of this  Agreement  until
               the status of discussions  concerning such  transaction  warrants
               such  disclosure.  In addition,  either party (or either  party's
               Affiliates)  may  disclose  the  terms  and  conditions  of  this
               Agreement as such party deems  appropriate to prepare for IPOs or
               major corporate transactions. Any disclosure to such entity shall
               be  substantially  under  the  same  confidentiality   terms  and
               conditions as provided herein.

     20.3. Exclusions.

          "Confidential  Information"  shall exclude any particular  information
          that the Receiving Party can demonstrate:

          (a)  At the time of  disclosure,  was in the  public  domain or in the
               rightful possession of the Receiving Party;

          (b)  After  disclosure,  is published or otherwise becomes part of the
               public domain through no fault of the Receiving Party;

          (c)  Was received after disclosure from a third party who had a lawful
               right to disclose such information to the Receiving Party without
               any obligation to restrict its further use or disclosure; 

                                       33
<PAGE>

          (d)  Was  independently  developed  by  the  Receiving  Party  without
               reference to Confidential Information of the Disclosing Party; or

          (e)  Was required to be disclosed to satisfy a legal  requirement of a
               competent  government  body;  provided  that,   immediately  upon
               receiving  such  request and to the extent that it may legally do
               so, the Receiving Party advises the Disclosing Party promptly and
               prior to making  such  disclosure  in order  that the  Disclosing
               Party may interpose an objection to such disclosure,  take action
               to assure confidential handling of the Confidential  Information,
               or take such other action as it deems  appropriate to protect the
               Confidential Information.

     20.4. No Implied Rights.

          Nothing  contained in this Section  shall be construed as obligating a
          party to disclose its Confidential  Information to the other party, or
          as granting to or conferring on a party,  expressly or impliedly,  any
          rights or license to the Confidential Information of the other party.

     20.5  Communication With FCC.

          Communications  by either  party with the FCC  regarding  the  subject
          matter of this  Agreement  shall  require  the other's  prior  written
          approval.

21 . DEFAULT

     A party shall not be in material breach of this Agreement  unless and until
     the  other   party   provides   it  written   notice  of  default  and  the
     non-performing  party has  failed to cure  within  thirty  (30) days  after
     receipt of such  notice.  Any event of default  may be waived in writing at
     the  non-defaulting  party's option.  Upon the failure of a party to timely
     cure its material breach hereunder  within the applicable cure period,  the
     non-defaulting  party shall have the right to (i) terminate  this Agreement
     or (ii)  subject to the terms of Article 23,  pursue any legal  remedies it
     may have under  applicable  law or  principles  of equity  relating to such
     breach.

22.  FORCE MAJEURE

     22.1. Excusable Delay.

          Neither  Williams nor WinStar shall be in default under this Agreement
          as a result of any delay in its  performance  (other than a failure to
          make  payments  when due) caused by any  elements of nature or acts of
          God, fire, explosion,  vandalism, power outage,  earthquake,  flood or
          lightning;  any civil or military  authority;  by national  emergency,
          insurrection, rebellion, revolution, riot, civil disorders, war or act
          of terrorism;  by cable cuts; or any other cause beyond the reasonable
          control  of  such  party   (collectively,   "Force  Majeure  Events");
          provided,  however, that (i) the non-performing party is without fault
          in causing such default or delay, and (ii) such default or delay could
          not  have  been  prevented  by  reasonable   precautions   and  cannot
          reasonably be circumvented by the non-performing party through the use
          of alternate  sources  (e.g.,  other  suppliers of  telecommunications
          services or  capacity),  workaround  plans or other  means,  including
          means  contemplated  by  applicable  disaster  recovery  processes  or
          procedures).

                                       34
<PAGE>

     22.2. Notice and Remedy.

          In such event the  non-performing  party shall be excused from further
          performance or observance of the obligation(s) so affected for as long
          as  such  circumstances  prevail  and  such  party  continues  to  use
          commercially   reasonable   efforts  to  recommence   performance   or
          observance whenever and to whatever extent possible without delay. The
          non-performing  party  shall  immediately  notify  the other  party by
          telephone (to be confirmed in writing  within two (2) business days of
          the  inception of such delay) and  describe at a  reasonable  level of
          detail the Force  Majeure  Event  causing  such delay and the expected
          duration of the Force Majeure  Event.  The  non-performing  party will
          provide the other party  prompt  written  notice of the  cessation  or
          termination of the Force Majeure Event.

23.  REMEDIES AND DISPUTE RESOLUTION

     23.1. Dispute Resolution.

          Any dispute  between  the  Parties  arising out of or relating to this
          Agreement,   the   interpretation  of  any  provision  hereof  or  the
          performance  or failure to perform  of  Williams  or WinStar  shall be
          resolved as provided in this Article 23.

     23.2. Cumulative Remedies.

          Except as otherwise  expressly  provided herein, all remedies provided
          for in this  Agreement  shall be cumulative and in addition to and not
          in lieu of any other  remedies  available  to either  party at law, in
          equity or otherwise.

     23.3. Informal Dispute Resolution.

          (a)  Prior to the initiation of formal dispute  resolution  procedures
               (i.e.,  arbitration),  the parties shall first attempt to resolve
               their  dispute  at the  senior  manager  level.  If that level of
               dispute  resolution is not successful,  the parties shall proceed
               informally, as follows:

               (i)  Upon the written  request of either party,  each party shall
                    appoint a designated  representative  who does not otherwise
                    devote  substantially  full time to  performance  under this
                    Agreement,  whose task it will be to meet for the purpose of
                    endeavoring to resolve such dispute.

               (ii) The  designated  representatives  shall meet as often as the
                    parties  reasonably  deem  necessary  in order to gather and
                    furnish  to the other all  information  with  respect to the
                    matter in issue that the parties  believe to be  appropriate
                    and  germane  in  connection   with  its   resolution.   The
                    representatives  shall  discuss  the  problem and attempt to
                    resolve the  dispute  without  the  necessity  of any formal
                    proceeding.

                                       35
<PAGE>

               (iii)During the course of  discussion,  all  reasonable  requests
                    made   by  one   party   to   another   for   non-privileged
                    non-confidential  information  reasonably  related  to  this
                    Agreement  shall be honored so that each of the  parties may
                    be fully advised of the other's position.

               (iv) The specific format for the discussions shall be left to the
                    discretion of the designated representatives. 

          (b)  Prior to instituting formal  proceedings,  the parties will first
               have their chief executive  officers meet to discuss the dispute.
               This  requirement  shall  not  delay  the  institution  of formal
               proceedings  past any statute of  limitations  expiration  or for
               more than fifteen (15) days.

          (c)  Subject to Subsection (b), formal  proceedings for the resolution
               of a dispute may not be  commenced  until the earlier of: 

               (i)  The designated representatives concluding in good faith that
                    amicable  resolution  through  continued  negotiation of the
                    matter does not appear likely; or

               (ii) Thirty  (30)  days  after the  initial  written  request  to
                    appoint a designated  representative  pursuant to Subsection
                    (a),   above,   (this   period   shall  be   deemed  to  run
                    notwithstanding any claim that the process described in this
                    Section 23.3 was not followed or completed).

          (d)  This  Section 23.3 shall not be construed to prevent a party from
               instituting,  and a party  is  authorized  to  institute,  formal
               proceedings  earlier to avoid the  expiration  of any  applicable
               limitations  period,  or to  preserve  a superior  position  with
               respect to other creditors or as provided in Section 23.6.

     23.4. Arbitration.

          If the  Parties  are unable to resolve a dispute  as  contemplated  by
          Section 23.3,  then except as provided by Section  23.6,  such dispute
          shall  be  submitted  to  mandatory  and  binding  arbitration  at the
          election  of  either  WinStar  or  Williams  (the  "Disputing  Party")
          pursuant to the following conditions:

          (a)  The  Disputing  Party  shall  notify  the  American   Arbitration
               Association ("AAA") and the other party, describing in reasonable
               detail the nature of the  dispute  (the  "Dispute  Notice");  and
               shall  request  that the AAA furnish a list of five (5)  possible
               arbitrators    who   have    substantial    experience   in   the
               telecommunications  industry.  Each party shall have fifteen (15)
               days to reject two (2) of the proposed  arbitrators.  If only one
               individual  has not been so rejected,  that person shall serve as
               arbitrator;  if two  (2) or more  individuals  have  not  been so
               rejected,   the  AAA  shall  select  the  arbitrator  from  those
               individuals.

                                       36

<PAGE>

          (b)  The  arbitration  shall  take  place  in  Chicago,  Illinois,  in
               accordance with the Commercial  Arbitration Rules of the American
               Arbitration Association in effect on the date that such notice is
               provided.   The  arbitration  shall  be  commenced  promptly  and
               conducted expeditiously.  The parties shall be entitled to submit
               expert testimony and/or written documentation on such arbitration
               proceeding.  The  decision of the  arbitrator  shall be final and
               binding  upon  Williams  and  WinStar and shall  include  written
               findings of law and fact, and judgment may be obtained thereon by
               either Williams or WinStar in a court of competent  jurisdiction.
               Williams and WinStar  shall each bear the cost of  preparing  and
               presenting its own case. The cost of the  arbitration,  including
               the fees and expenses of the arbitrator,  shall be shared equally
               by Williams and WinStar unless the award otherwise provides.  The
               arbitrator shall be instructed to establish  procedures such that
               a  decision  can  be  rendered  within  sixty  (60)  days  of the
               appointment of the arbitrator.

          (c)  The  obligation to arbitrate  shall not be binding upon any party
               with respect to requests for preliminary  injunctions,  temporary
               restraining orders, specific performance,  or other procedures in
               a court of competent  jurisdiction  to obtain interim relief when
               deemed  necessary  by such  court to  preserve  the status quo or
               prevent  irreparable  injury pending resolution by arbitration of
               the actual dispute.

          (d)  Any arbitrator  appointed to act under this Article must agree to
               be bound by the provisions of this Agreement and any  information
               obtained  during the course of the  arbitration  proceedings.  In
               particular,  the  arbitrator  shall  not  have the  authority  to
               exclude the right of a Party to terminate  this  Agreement when a
               Party would otherwise have such right.  The  arbitration  hearing
               shall be commenced promptly and conducted expeditiously.

          (e)  Should  the  arbitrator  refuse  or be  unable  to  proceed  with
               arbitration  proceedings  as  called  for by this  Section,  such
               arbitrator  shall be replaced and a rehearing shall take place in
               accordance with the provisions of this Section. In such case, the
               replacement  for the arbitrator  shall be either  selected by the
               AAA from the original  group of potential  arbitrators  that were
               not rejected by the parties or, if there are no such  arbitrators
               available,   selected  by  repeating  the  process  of  selection
               described in 23.4(a).

          (f)  The  arbitrator is instructed  that time is of the essence in the
               arbitration  proceeding,  and that the arbitrator  shall have the
               right and authority to issue monetary sanctions against either of
               the  parties  if,  upon a showing  of good  cause,  that party is
               unreasonably  delaying the  proceeding.  Recognizing  the express
               desire  of  the  parties  for an  expeditious  means  of  dispute
               resolution,  the  arbitrator  shall limit or allow the parties to
               expand  the scope of  discovery  as may be  reasonable  under the
               circumstances.

                                       37
<PAGE>

     23.5. Continued Performance.

          Each party agrees to continue  performing its  obligations  under this
          Agreement while any dispute is being resolved except to the extent the
          issue in dispute precludes performance.

     23.6. Immediate Injunctive Relief.

          The only  circumstance in which disputes between the parties shall not
          be  subject  to the  provisions  of  Section  23.3 and 23.4 is where a
          party, in good faith, determines that a temporary restraining order or
          other  injunctive  relief is its only appropriate and adequate remedy.
          If a party seeks immediate  injunctive  relief and does not prevail in
          substantial  part,  that party shall pay the other  party's  costs and
          attorneys' fees to the extent incurred in responding to or challenging
          the request for immediate injunctive relief.

24.  GENERAL

     24.1. Rules of Construction.

          (a)  The  captions or  headings in this  Agreement  are  strictly  for
               convenience  and shall not be  considered  in  interpreting  this
               Agreement or as amplifying or limiting any of its content.  Words
               in this Agreement that import the singular  connotation  shall be
               interpreted   as  plural,   and  words  that  import  the  plural
               connotation shall be interpreted as singular,  as the identity of
               the parties or objects  referred to may  require.  References  to
               "person"  or  "entity"  each  include  natural  persons and legal
               entities,  including  corporations,  limited liability companies,
               partnerships,    sole   proprietorships,    business   divisions,
               unincorporated  associations,   governmental  entities,  and  any
               entities  entitled  to bring an action in, or that are subject to
               suit in an  action  before,  any  state or  federal  court of the
               United States.

          (b)  Unless  expressly   defined  herein,   words  having   well-known
               technical or trade meanings shall be so construed.

          (c)  Except as set forth to the contrary  herein,  any right or remedy
               of Williams or WinStar shall be cumulative and without  prejudice
               to any other right or remedy, whether contained herein or not.

          (d)  Nothing in this Agreement is intended to provide any legal rights
               to anyone not an executing  party of this Agreement  except under
               the indemnification and insurance  provisions and except that (i)
               the  Released  Parties  shall have the benefit of Sections  16.3,
               24.2(a) and 24.5(a) and (ii) the Facility Owners/Lenders shall be
               entitled  to rely on and have the  benefit of  Sections  13.2 and
               24.5(b).

                                       38
<PAGE>

          (e)  This  Agreement has been fully  negotiated  between  Williams and
               WinStar.

          (f)  In the  event  of a  conflict  between  the  provisions  of  this
               Agreement  and  those  of any  Exhibit,  the  provisions  of this
               Agreement  shall  prevail  and such  Exhibit  shall be  corrected
               accordingly,  provided  that the  provisions  of  Exhibit K shall
               prevail over  conflicting  provisions  in the Agreement or in any
               Exhibit. Notwithstanding the above, terms defined in Section 7 of
               Exhibit K shall not  supersede  terms defined in the Agreement or
               in other Exhibits except as used in Exhibit K.

          (g)  Except as  otherwise  set forth  herein,  for the purpose of this
               Agreement  the  normal   standards  of  performance   within  the
               telecommunications  industry in the relevant  market shall be the
               measure  of  whether  a party's  performance  is  reasonable  and
               timely.

          (h)  Except as the context  otherwise  indicates,  all  references  to
               Exhibits,   Articles,   Sections,   Subsections,   Clauses,   and
               Paragraphs refer to provisions of this Agreement.

          (i)  The  failure of either  Williams or WinStar 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.

          (j)  This  Agreement  shall be governed by and construed in accordance
               with the domestic laws of the State of New York without reference
               to its  choice  of  law  principles.  All  disputes  referred  to
               arbitration  and the statute of limitations  and the remedies for
               any wrongs  that may be found  shall be  governed  by the laws of
               such state.  If a proceeding  is brought for the  enforcement  of
               this  Agreement  or  because of any  alleged  or actual  dispute,
               breach,  default or  misrepresentation  in connection with any of
               the provisions of this Agreement,  the prevailing  party shall be
               entitled to recover  reasonable  attorneys'  fees and other costs
               and expenses incurred in such action or proceeding in addition to
               any other relief to which such party may be entitled.

          (k)  If any term,  covenant or condition in this Agreement  shall,  to
               any extent,  be invalid or unenforceable in any respect under the
               laws  governing this  Agreement,  the remainder of this Agreement
               shall  not be  affected  thereby,  and  each  term,  covenant  or
               condition of this Agreement shall be valid and enforceable to the
               fullest extent permitted by law.

          (l)  The  parties   acknowledge   and  agree  that:  (i)  the  payment
               deductions  ("Payment  Deductions") set forth in Sections 5.2(g),
               6.1(c) and 10.4  (collectively,  the "Deduction  Sections") shall
               not limit  Williams'  liability  or serve as a sole or  exclusive
               remedy for Williams' default under any portion of this Agreement;
               (ii)  WinStar  may seek any other  rights or remedies it may have
               against  Williams  for any default  hereunder;  (iii) none of the
               Deduction  Sections  modify or otherwise  limit any other term or
               condition  of this  Agreement;  (iv) the one  hundred  and twenty
               (120) day periods specified in the Deduction  Sections shall only
 
                                       39
<PAGE>


               be  applicable  with respect to the  Deduction  Sections and such
               periods shall in no manner whatsoever be construed or interpreted
               to extend  Williams'  cure  periods or other  timing of any other
               obligation  set forth in any other  provision of this  Agreement;
               and (v) WinStar's  compliance  with the Deduction  Sections shall
               not  constitute a breach of the Payment  Terms.  Williams  hereby
               waives any rights it may have to use the Deduction  Sections as a
               claim or defense against any other provision in this Agreement.

     24.2. Assignment.

          (a)  Except to the extent permitted by Section 24.2(d),  neither party
               may,  or shall  have the  power  to,  assign  this  Agreement  or
               delegate  such party's  obligations  hereunder  without the prior
               written consent of the other except to:

               (i)  An entity  that  acquires  all or  substantially  all of the
                    assets of such party,

               (ii) Any Affiliate,

               (iii) A successor in a merger or acquisition of such party, or

               (iv) In connection with any financing.

          (b)  Notwithstanding the foregoing, no assignment or other transfer of
               this Agreement shall be effective  without the written  agreement
               of the assignee to be bound by the terms and  conditions  of this
               Agreement   including   the   indemnification    provisions   and
               limitations on liability and recourse set forth in this Agreement
               (including those benefiting the Released Parties).

          (c)  Except  with  respect  to the  assignment  of less  than all of a
               party's rights or obligations  under this Agreement and except as
               set forth in Section 24.2(e),  the non-assigning  party shall not
               unreasonably withhold its consent to an assignment if neither the
               assigning party nor the proposed  assignee is in material default
               under   this   Agreement   or  any  other   agreement   with  the
               non-assigning party.

          (d)  The provisions of Section 24.2(a)  notwithstanding,  Williams may
               assign  some or all of its rights and  obligations  hereunder  to
               State  Street  Bank and Trust  Company of  Connecticut,  National
               Association,  in  connection  with a  financing  by  Williams  of
               construction  of its fiber  optic  network;  in  addition,  State
               Street   Bank  and  Trust   Company  of   Connecticut,   National
               Association,  may further assign this Agreement as collateral for
               such financing.  If Williams makes an assignment pursuant to this
               Subsection  24.2(d),  Williams  (or its  assignee  pursuant to an
               assignment made under the other  provisions of this Section 24.2)
               shall guarantee performance of the assignee's obligations.

                                       40
<PAGE>

          (e)  Except in  connection  with an  assignment  of this  Agreement as
               provided  herein,  until  the  third  (3rd)  anniversary  of  the
               Acceptance Date of any System Segment, WinStar shall not sell the
               dark fiber,  raw frequency  (commonly known as "windows") but may
               place optronics in such System Segment and resell capacity in any
               increment.  After such three (3) year period,  WinStar may convey
               such an interest  provided  that WinStar  shall serve as the sole
               point  of  contact  with  Williams  and no party  receiving  such
               interest shall have any contract  rights against or be in privity
               of contract with Williams as a result of such conveyance.

          (f)  This  Agreement  and  the  rights  and  obligations   under  this
               Agreement  (including  the  limitations on liability and recourse
               set forth in this  Agreement  benefiting  the other party and the
               Released  Parties)  shall be binding  upon and shall inure to the
               benefit of Williams  and WinStar and their  respective  permitted
               successors and assigns.

          (g)  Neither the  provisions of this Article nor any other  provisions
               of  this  Agreement  shall  limit  the  ability  of any  Facility
               Owners/Lenders  or of any Released Parties to assign their rights
               under  this  Agreement  and  such  Facility   Owners/Lenders  and
               Released  Parties may assign their  rights  hereunder at any time
               and from time to time  without the consent of,  notice to, or any
               other  action  by  any  other  entity.  The  provisions  of  this
               Agreement  benefiting  the Facility  Owners/Lenders  and Released
               Parties  shall  inure to the benefit of such  entities  and their
               respective Affiliates, successors, and assigns.

          (h)  Notwithstanding  any presumptions under applicable state law that
               a change in control of a party  constitutes  an  assignment of an
               agreement,  a change in control of a party, not made for purposes
               of  circumventing  restrictions on assignment or of depriving the
               other party of rights under this  Agreement,  shall not be deemed
               an assignment for purposes of this Agreement.

     24.3. Relationship of the Parties.

          The  relationship  between  Williams and WinStar  shall not be that of
          partners,  agents,  or joint  venturers  for one another,  and nothing
          contained  in  this   Agreement   shall  be  deemed  to  constitute  a
          partnership  or  agency  agreement  between  them  for  any  purposes,
          including  federal  income tax  purposes.  Williams  and  WinStar,  in
          performing any of their  obligations  hereunder,  shall be independent
          contractors  or  independent   parties  and  shall   discharge   their
          contractual obligations at their own risk.

     24.4. Prohibition on Improper Payments.

          Neither party shall use any funds  received  under this  Agreement for
          illegal or otherwise "improper" purposes.  Neither party shall pay any
          commission,  fees or rebates to any  employee of the other  party.  If
          either  party  has  reasonable  cause  to  believe  that  one  of  the

                                       41
<PAGE>

          provisions   in  this   Article   has  been   violated,   it,  or  its
          representative, may audit the books and records of the other party for
          the sole purpose of establishing compliance with such provisions.

     24.5. Entire Agreement; Amendment; Execution.

          (a)  This  Agreement  constitutes  the entire and final  agreement and
               understanding  between  Williams  and WinStar with respect to the
               subject matter hereof and supersedes all prior  agreements  (oral
               or written)  relating to the subject matter hereof,  which are of
               no  further  force  or  effect  (including,  in  particular,  the
               Customer Services Agreement between Williams and WinStar GoodNet,
               dated July 16, 1998,  Contract Number  98R0675.00,  provided that
               any  undisputed  payment   obligations   accruing  prior  to  the
               Effective  Date,  shall be due and owing  under the terms of this
               Agreement).  The Exhibits  referred to herein are integral  parts
               hereof and are made a part of this Agreement by reference.

          (b)  This Agreement may only be amended,  modified, or supplemented by
               an instrument  in a single  writing  executed by duly  authorized
               representatives  of  Williams  and  WinStar.  No such  amendment,
               modification,  or supplement  shall result in any modification of
               (i) any indemnity benefiting any Facility Owners/Lenders or their
               respective  Affiliates  or (ii) any  limitation  of  liability or
               recourse  benefiting any Released Parties that is adverse to such
               Released Parties.

          (c)  This Agreement may be executed in one or more  counterparts,  all
               of  which  taken  together  shall  constitute  one and  the  same
               instrument.

          (d)  This  Agreement  may be duly executed and delivered by a party by
               execution  and  facsimile  delivery  of the  signature  page of a
               counterpart  to the other party,  provided  that,  if delivery is
               made by facsimile,  the executing party shall promptly  deliver a
               complete counterpart that it has executed to the other party.

          (e)  Unless otherwise expressly permitted in this Agreement,  Williams
               shall not make any changes to the Exhibits or Schedules  attached
               hereto that may have a material adverse impact on the performance
               or  usability  of  the  Telecommunications  Services,  Additional
               Services  or  Other  Services  without  WinStar's  prior  written
               consent.

     24.6 Public Disclosures.

          All media  releases,  public  announcements,  and  public  disclosures
          relating to this  Agreement or the subject  matter of this  Agreement,
          including  promotional  or  marketing  material,   but  not  including
          announcements intended solely for internal distribution or disclosures
          to the extent required to meet legal or regulatory  requirements shall
          be  coordinated  with and shall be subject to approval by both parties
          prior to release.

                                       42
<PAGE>

25.  REPRESENTATIONS, WARRANTIES AND COVENANTS

     25.1. Representations and Warranties.

          In addition to any other  representations and warranties  contained in
          this Agreement, each party hereto represents and warrants to the other
          that:

          (a)  It has the  requisite  corporate  power to enter  into,  execute,
               deliver, and perform its obligations under this Agreement;

          (b)  It has taken  all  requisite  corporate  action  to  approve  the
               execution, delivery, and performance of this Agreement;

          (c)  This Agreement  constitutes a legal, valid and binding obligation
               enforceable against such party in accordance with its terms;

          (d)  Its execution of and  performance  under this Agreement shall not
               violate any applicable existing regulations,  rules, statutes, or
               court orders of any local,  state, or federal  government agency,
               court, or body;

          (e)  It is not subject to any  contractual  or other  obligation  that
               would prevent it from entering into this relationship;  and 

          (f)  It has not offered or provided  any  inducements  in violation of
               law or the other  party's  policies,  of which it has been  given
               notice,  in  connection  with this  Agreement.  

     25.2. Additional Williams Covenants.

          Excluding  services  provided by third  parties  other than  Williams'
          subcontractors,  Williams covenants that Telecommunications  Services,
          Additional  Services,  and Other Services shall be provided to WinStar
          in  accordance  with  the  technical   parameters  set  forth  in  the
          applicable service schedule.  Williams further covenants that it shall
          use commercially  reasonable efforts under the circumstances to remedy
          any delays, interruptions, omissions, mistakes, accidents or errors in
          the Telecommunications Services, Additional Services or Other Services
          provided hereunder and to restore such Telecommunications  Services or
          Other Services to compliance with the terms hereof.

     25.3. Infringement of Intellectual Property Rights.

          Each party  represents,  warrants  and  covenants to the other that it
          shall perform its  responsibilities  under this  Agreement in a manner
          that  does  not   infringe,   or   constitute   an   infringement   or
          misappropriation  of, any  Intellectual  Property  Rights of any third
          party.

26.  USE OF TELECOMMUNICATIONS AND OTHER SERVICES

     26.1. Condition to Provision of Services.

          Telecommunications  Services or Other  Services  shall not be used for
          any unlawful purpose. More than ten percent (10%) of the transmissions

                                       43
<PAGE>

          will be interstate transmissions.  The parties represent to each other
          that this Agreement, to the extent it is subject to FCC regulation, is
          an inter-carrier  agreement not subject to the filing  requirements of
          Section 211 (a) of the  Communications  Act of 1934,  as amended.  One
          strand of the  Williams  Network is  contractually  limited to use for
          multimedia  transmission  (i.e.  internet  traffic,  video  and  radio
          transmission services and/or related applications, including, graphic,
          visual,  imaging,   interactive  and  multimedia  transmissions)  (the
          "Restricted Fiber"). If the parties want to use such Restricted Fiber,
          upon request from Williams,  WinStar agrees within a reasonable period
          of time to  identify  the  nature  of its  proposed  use of the  Other
          Service  so as to  permit  Williams  to  determine  whether  the Other
          Service  may be  carried  over the  Restricted  Fiber.  The fact  that
          Williams may not utilize the Restricted  Fiber for such  transmissions
          shall not affect  Williams'  obligation to provide  Telecommunications
          Services or Other Services unless otherwise  specifically set forth in
          this Agreement.

     26.2. Intrastate Interexchange Services.

          WinStar  may  use  any  interexchange   service  provided  under  this
          Agreement  including  any  service  provided  by means  of a  Backbone
          Agreement  only if such  interexchange  service  is used for  carrying
          inter-state  (as  defined  by  the  FCC)   telecommunications   (i.e.,
          telecommunications   subject  to  the   jurisdiction  of  the  Federal
          Communications  Commission).  Williams and its Affiliates shall not be
          obligated to make available  Telecommunications  Services,  Additional
          Services,  or other interexchange service on a Circuit with end points
          within   a   single   state   or   service   on   a   Circuit    which
          originates/terminates  at points both of which are  situated  within a
          single  state  unless   WinStar   represents   in  writing  that  such
          interexchange  service or Circuits shall be used to carry  inter-state
          telecommunications (as defined by the FCC).

     26.3. WinStar Responsibilities.

          WinStar  has  sole   responsibility  for  installation,   testing  and
          operation of facilities, services and equipment ("WinStar Facilities")
          other than those  specifically  provided  by  Williams  as part of the
          Telecommunications  Services  or  Other  Services  as  described  in a
          Service  Order.  In  no  event  will  the  untimely   installation  or
          non-operation of WinStar  Facilities relieve WinStar of its obligation
          to pay charges for the Service or Other  Service  after the  Requested
          Start Date as set forth in the Service Order.

     26.4. Consents.

          As  between  the  parties,   WinStar  shall  be  responsible  for  all
          arrangements with copyright  holders,  music licensing  organizations,
          performers'   representatives   or   other   parties   for   necessary
          authorizations,  clearances or consents  with respect to  transmission
          contents.

                                       44
<PAGE>

     26.5. Restriction of Transmissions.

          WinStar  will not  transmit  content,  nor  permit  its  customers  to
          transmit   content  that  violates   applicable   law  or  carries  an
          unreasonable  risk of leading  to  criminal,  civil or  administrative
          proceedings or investigations against Williams or WinStar.
         
     26.6 Compliance with Regulations.

          If the FCC,  any state  regulatory  body,  or any court,  in each case
          having competent  jurisdiction,  determines that any provision of this
          Agreement  violates any applicable  rules,  policies,  or regulations,
          both parties  shall  reasonably  cooperate to  immediately  bring this
          Agreement  into  compliance,   consistent  with  the  intent  of  this
          Agreement.

     26.6. Reasonableness, Consents and Approval.

          (a)  Where this  Agreement  requires  a party to assist or  cooperate,
               such requirement  shall not be interpreted to require  materially
               more than a  commercially  reasonable  level of effort (i.e.  the
               standard applicable will not be "best efforts" or "exhausting all
               available means").

          (b)  Except where  expressly  provided as being in the sole discretion
               of a party, where agreement,  approval,  acceptance,  consent, or
               similar action by either party is required under this  Agreement,
               such action shall not be  unreasonably  delayed or  withheld.  An
               approval or consent given by a party under this  Agreement  shall
               not  relieve the other party from  responsibility  for  complying
               with  the  requirements  of  this  Agreement,  nor  shall  it  be
               construed as a waiver of any rights under this Agreement,  except
               as  and  to the  extent  otherwise  expressly  provided  in  such
               approval or consent.


                                       45

<PAGE>



         IN WITNESS  WHEREOF and in  confirmation  of their consent to the terms
and  conditions  contained in this  Agreement  and intending to be legally bound
hereby,  Williams and WinStar have executed and delivered  this  Agreement as of
the dates set forth below.

<TABLE>

<S>                                                            <C> 
WINSTAR WIRELESS, INC.                                          WILLIAMS COMMUNICATIONS, INC.



               /s/ Timothy R. Graham                                            /s/ Frank Semple
By:           --------------------------------------------      By:            ----------------------------------------
               Timothy R. Graham                                                Frank Semple
Name:         --------------------------------------------      Name:          ----------------------------------------
               Vice President                                                   President, Williams Network
Title         --------------------------------------------      Title:         ----------------------------------------
               December 17, 1998                                                December 17, 1998
Date:         --------------------------------------------      Date:          ----------------------------------------

</TABLE>

                                       46




                                                 Confidential - WinStar/Williams






                         WIRELESS FIBERsm IRU AGREEMENT


                                 BY AND BETWEEN


                             WINSTAR WIRELESS, INC.


                                       AND


                          WILLIAMS COMMUNICATIONS, INC.






                        Effective as of December 17, 1998




<PAGE>

                                TABLE OF CONTENTS
<TABLE>
<S>                                                                                                              <C>

1.   DEFINITIONS..................................................................................................1
1.1.   Particular Terms...........................................................................................1
1.2.   Other Terms................................................................................................4

2.   SCOPE AND STRUCTURE..........................................................................................4
2.1.   General....................................................................................................4
2.2.   Term.......................................................................................................5
2.3.   Strategic Relationship.....................................................................................5

3.   GRANTS, RIGHTS AND RESPONSIBILITIES..........................................................................6
3.1.   WinStar Grant, Rights and Responsibilities.................................................................6
3.2.   WinStar Acceptance and Testing.............................................................................7
3.3.   Control of Facilities......................................................................................7
3.4.   Provisioning of Williams T-1s..............................................................................8
3.5.   Service Orders for Williams T-1s...........................................................................9
3.6.   Changes in Service Parameters.............................................................................10
3.7.   Delivery of Minimum Williams T-1 Inventory................................................................10

4.   OTHER PERFORMANCE AND SERVICES..............................................................................11
4.1.   Interconnection...........................................................................................11
4.2.   Collocation...............................................................................................11
4.3.   Maintenance...............................................................................................11
4.4.   Routine Maintenance.......................................................................................11
4.5.   Non-Routine Maintenance...................................................................................12
4.6.   Subcontractors............................................................................................12
4.7.   Williams Equipment........................................................................................12
4.8.   Performance Standards.....................................................................................12
4.9.   Disengagement Assistance..................................................................................12
4.10.  Relocation................................................................................................12
4.11.  Ancillary Services........................................................................................13

5.   CONTRACT ADMINISTRATION.....................................................................................13
5.1.   Reports and Meetings......................................................................................13
5.2.   Confidentiality...........................................................................................14

6.   CHARGES.....................................................................................................16
6.1.   General...................................................................................................16
6.2.   Taxes.....................................................................................................16
6.3.   Pass-Through Expenses.....................................................................................17
6.4.   Most Favored Customer Status..............................................................................17
6.5.   Benchmarking..............................................................................................18

7.   INVOICING AND PAYMENT.......................................................................................18
7.1.   Invoicing.................................................................................................18
7.2.   Payment Due...............................................................................................18
7.3.   Disputed Charges..........................................................................................19
7.4.   Late Interest.............................................................................................19

8.   COVENANTS, REPRESENTATIONS AND WARRANTIES...................................................................19
8.1.   Non-Infringement..........................................................................................19
8.2.   Authorization.............................................................................................19
8.3.   Wireless Fiber Connectivity...............................................................................20
8.4.   Disclaimer................................................................................................20

9.   INDEMNIFICATION.............................................................................................20
9.1.   Indemnities by Williams...................................................................................20
9.2.   Indemnities by WinStar....................................................................................21
9.3.   Indemnification Procedures................................................................................22
</TABLE>

                                      - i -
<PAGE>

<TABLE>
<S>                                                                                                             <C>
10.  LIABILITY, RISK OF LOSS AND INSURANCE.......................................................................22
10.1.  General Intent............................................................................................22
10.2.  Liability Restrictions....................................................................................23
10.3.  Insurance Requirements....................................................................................23
10.4.  Risk of Loss..............................................................................................24
10.5.  Force Majeure.............................................................................................24

11.  REMEDIES AND DISPUTE RESOLUTION.............................................................................25
11.1.  Cumulative Nature.........................................................................................25
11.2.  Informal Dispute Resolution...............................................................................25
11.3.  Arbitration...............................................................................................26
11.4.  Termination...............................................................................................27
11.5.  Suspension of Service.....................................................................................27
11.6.  Litigation................................................................................................27
11.7.  Continued Performance.....................................................................................28

12.  GENERAL.....................................................................................................28
12.1.  Binding Nature and Assignment.............................................................................28
12.2.  Entire Agreement..........................................................................................28
12.3.  Tariff....................................................................................................28
12.4.  Consents..................................................................................................29
12.5.  Restriction of Transmissions..............................................................................29
12.6.  Use and Ownership.........................................................................................29
12.7.  Non-Solicitation..........................................................................................29
12.8.  Notices...................................................................................................29
12.9.  Counterparts..............................................................................................30
12.10. Relationship of Parties...................................................................................30
12.11. Severability..............................................................................................30
12.12. Reasonableness, Consents and Approval.....................................................................30
12.13. Waiver of Default.........................................................................................30
12.14. Survival..................................................................................................31
12.15. Public Disclosures........................................................................................31
12.16. Third Party Beneficiaries.................................................................................31
12.17. Amendment.................................................................................................31
12.18. Order of Precedence.......................................................................................31
12.19. Interpretation............................................................................................32
12.20. Covenant of Good Faith....................................................................................32
</TABLE>



                        LIST OF SCHEDULES AND EXHIBITS
- - --------------------------------------------------------------------------------
Schedule A        Scope and Services
                  Exhibit A-1: WinStar Target Markets
                  Exhibit A-2: Implementation Schedule
                  Exhibit A-3: Collocation
                  Exhibit A-4: Standards and Specifications
                  Exhibit A-5: Hub Implementation Forecast
                  Exhibit A-6: Williams Connectivity
Schedule B        Performance Standards
Schedule C        Charges


                                       ii


<PAGE>




                         WIRELESS FIBERsm IRU AGREEMENT

                                 BY AND BETWEEN

                             WINSTAR WIRELESS, INC.

                                       AND

                          WILLIAMS COMMUNICATIONS, INC.




         This WIRELESS FIBER IRU AGREEMENT (including the Exhibits and Schedules
attached  hereto,  the  "Agreement"),  effective  as of  December  17, 1998 (the
"Effective  Date"),  is entered into by and between  WINSTAR  WIRELESS,  INC., a
Delaware corporation with offices located at 230 Park Avenue, New York, New York
10169 ("WinStar"),  and WILLIAMS  COMMUNICATIONS,  INC., a Delaware  corporation
with offices located at One Williams Center, Tulsa, Oklahoma 74172 ("Williams").


         WHEREAS,  WinStar  is  a  fixed  wireless  services  telecommunications
provider  currently  planning to build-out in the  domestic  major  metropolitan
markets set forth in Exhibit A-1;


         WHEREAS,  Williams is a provider of high capacity long haul fiber optic
network transport and desires to utilize WinStar's  Wireless Fiber  Connectivity
(as hereinafter defined) in conjunction with its long haul network services; and


         WHEREAS,  upon the terms and subject to the conditions set forth below,
Williams  desires to acquire  from  WinStar,  and WinStar  desires to provide to
Williams, an exclusive,  indefeasible right to use certain of WinStar's Wireless
Fiber Connectivity on a private, non-common-carrier basis.


         NOW THEREFORE,  in consideration of the mutual promises set forth below
and  other  good and  valid  consideration,  the  receipt  of  which  is  hereby
acknowledged,  WinStar and Williams  (collectively,  the  "Parties"  and each, a
"Party") agree as follows:

1.   DEFINITIONS
     1.1. Particular Terms.

          As used in this Agreement:

          (a)  "Acceptance" has the meaning set forth in Exhibit A-4.

          (b)  "Acceptance  Date" means, for each Hub, the date of Acceptance as
               provided in Exhibit A-4.

          (c)  "Acceptance  Standards"  means the standards set forth in Exhibit
               A-4 with respect to the testing of the Hubs.

          (d)  "Affiliate"  means, with respect to any entity,  any other entity
               that directly,  or indirectly through one or more intermediaries,
               Controls,  or is Controlled  by, or is under common Control with,
               such entity.

                                       1
<PAGE>

          (e)  "Agreement"  has the  meaning  set forth in the  preamble to this
               Agreement.

          (f)  "Confidential  Information"  has the meaning set forth in Section
               5.2.

          (g)  "Control"  and  its  derivatives   means  legal,   beneficial  or
               equitable ownership,  directly or indirectly,  of more than fifty
               percent  (50%) of  outstanding  voting  capital  stock  (or other
               ownership  interest,  if  not  a  corporation)  of an  entity  or
               management or operational control over such entity.

          (h)  "Cost"  means  actual,  direct  costs  incurred  and  computed in
               accordance  with the  established  accounting  procedures used by
               WinStar to bill third  parties  for  reimbursable  projects.  All
               Costs shall be computed in  accordance  with  generally  accepted
               accounting principles. Such actual, direct costs include:

               (i)  Labor costs,  including  wages and  salaries,  and benefits,
                    plus the overhead  allocable  to such labor costs  (overhead
                    allocation  percentage  shall not  exceed the lesser of: (i)
                    the percentage  WinStar allocates to its internal  projects;
                    or (ii) ______ percent (__%)); and

               (ii) Other   direct  costs  and   Out-of-Pocket   Expenses  on  a
                    Pass-Through  Expenses basis (such as equipment,  materials,
                    supplies,  contract  services,  costs of  capital,  Required
                    Rights,  sales, use or similar taxes, etc.) plus ___ percent
                    (__%) of such expenses, but

               (iii) Less any cost or expense reimbursed by a third party.

          (i)  "Domestic  Hub  Capacity"  means,  at the time in  question,  the
               aggregate  capacity of WinStar's  deployed Hubs within the United
               States.

          (j)  "Effective  Date" has the  meaning  set forth in the  preamble to
               this Agreement.

          (k)  "Governmental  Authorizations"  means all  licenses,  permits and
               authorizations  from  the  Federal   Communications   Commission,
               Federal   Aviation    Administration,    state   public   utility
               commissions, municipal authorities or any other governmental body
               that are  materially  necessary  or  required  for or used in the
               business  and  operations  of  WinStar  or the  provision  of the
               Wireless Fiber Connectivity.

          (l)  "Hub" has the meaning set forth in Schedule A.

          (m)  "Indefeasible   Right  of  Use"  or  "IRU"  means  an  exclusive,
               indefeasible   right  to  use  the   specified   Wireless   Fiber
               Connectivity as contemplated by this Agreement.

          (n)  "Intellectual   Property   Rights"   means   patent,   copyright,
               trademark,  trade secret or other proprietary rights with respect
               to any work product in which such rights could inure.

                                       2
<PAGE>

          (o)  "Lit Building" means a building that, at the time in question, is
               either  a Hub  provided  by  WinStar  or  equipped  with a  radio
               connection  to a Hub  provided by WinStar  utilizing  spectrum in
               which WinStar holds a license.

          (p)  "Losses"  means all  liabilities,  damages and related  costs and
               expenses (including fines, levies, assessments,  reasonable legal
               fees and disbursements  and costs of  investigation,  litigation,
               settlement,  judgment,  interest and penalties) directly incurred
               by a Party.

          (q)  "Maintenance"  means the network  operations,  administration and
               maintenance required for the continued performance of the WinStar
               Fiberless Connectivity.

          (r)  "Minimum  Williams  T-1  Inventory"  has the meaning set forth in
               Exhibit A-6.

          (s)  "Out-of-Pocket    Expenses"    means    reasonable   and   actual
               out-of-pocket  expenses  incurred by a Party,  but not  including
               that   Party's   overhead   costs   (or   allocations   thereof),
               administrative expenses or other mark-ups.

          (t)  "Party" and "Parties" have the meanings set forth in the preamble
               to this Agreement.

          (u)  "Pass-Through Expenses" means certain WinStar expenses, as agreed
               to between the Parties in writing,  which Williams  agrees to pay
               directly or reimburse on an Out-of-Pocket Expenses basis.

          (v)  "Prime Rate" means, in respect of any period,  the rate published
               as Chase  Manhattan's  prime rate in the Wall Street Journal,  or
               any successor  publication thereto, from time to time during such
               period.

          (w)  "Pro Rata Share" means a proportion  equal, for Williams,  to the
               Williams  Connectivity  and, for WinStar,  the  complement of the
               Williams Connectivity.

          (x)  "Qualified  Building"  means  a  building  that,  at the  time in
               question,  has a verified line of sight (per  WinStar's  standard
               practices)  to a Hub  provided  by  WinStar  and  for  which  the
               necessary  Required Rights have been obtained by, or provided to,
               WinStar.

          (y)  "Required Rights" means leases or licenses for access to, and use
               of, building roof areas and other antenna  staging  locations and
               interior  space  and  conduit  rights  as  necessary  to  provide
               Wireless Fiber Connectivity to a building.

          (z)  "Sector"   means   an   area   of   coverage   emanating   off  a
               point-to-multipoint radio on a Hub.

          (aa) "Sector  Capacity"  of any  given  Hub  means,  as of the date in
               question,  the transport  capacity of the relevant Sector of that
               Hub.

          (bb) "Start Date" means,  with respect to any Williams  T-1, the first
               day on which such service is provided.

          (cc) "T-1" means a circuit  (wire,  fiber or spectrum) with a capacity
               of 1.544 Mbps.

                                       3
<PAGE>

          (dd) "Term" has the meaning set forth in Section 2.2.

          (ee) "Williams"  has the  meaning  set forth in the  preamble  to this
               Agreement.

          (ff) "Williams Connectivity" has the meaning given in Exhibit A-6.

          (gg) "Williams IRU" has the meaning given in Section 3.1(a).

          (hh) "Williams T-1" has the meaning given in Section 3.1(a). Each such
               circuit shall traverse __________________________________________
               _________________________________________________________________
               _____________________________ and shall be deemed  provided  when
               approved by Williams in accordance with Section 3.5(e).

          (ii) "WinStar"  has the  meaning  set  forth in the  preamble  to this
               Agreement.

          (jj) "WinStar Equipment" means the  telecommunications  equipment used
               by WinStar to implement the Wireless Fiber Connectivity.

          (kk) "WinStar  Target Market" means a city listed in Exhibit A-2 where
               WinStar  has at  least  one Hub to  provide  the  Wireless  Fiber
               Connectivity,  which list may be amended by WinStar  from time to
               time with notice to Williams (in accordance with Exhibit A-2).

          (ll) "Wireless  Fiber   Connectivity"   means  the  Wireless   Fibersm
               connectivity,  which  WinStar is authorized to provide at certain
               licensed radio frequency bandwidths.

     1.2. Other Terms.

          Other terms used in this Agreement are defined in the context in which
          they are used and have the meanings there indicated.

2.       SCOPE AND STRUCTURE

     2.1. General.

          (a)  This Agreement sets forth the general terms and conditions  under
               which WinStar grants Williams specific rights to certain capacity
               within the deployed Wireless Fiber Connectivity.


          (b)  The Parties  acknowledge  that this  Agreement  does not grant to
               WinStar an exclusive  privilege  to sell or otherwise  provide to
               Williams  any or all of the  transport  and  services of the type
               described in this  Agreement.  Williams  may contract  with other
               suppliers  for  the   procurement  of  comparable   transport  or
               services.  Subject to the Williams  IRU granted by WinStar  under
               this  Agreement,  WinStar is not restricted from selling to other
               entities any types of transport or services  including  the types
               of transport or services that are provided to Williams hereunder.

                                       4
<PAGE>

     2.2. Term.

          The term of this Agreement  (the "Term"),  with respect to each of the
          initial two hundred and  seventy  (270) Hubs  implemented  by WinStar,
          shall  begin on the  corresponding  Acceptance  Date and  continue  in
          effect for twenty-five (25) years from that time.

     2.3. Strategic Relationship.

          (a)  Resale of WinStar Product. Pursuant to terms to be agreed upon by
               the Parties after the Effective Date, WinStar will grant Williams
               the right to market and promote  certain  WinStar  voice and data
               products  (e.g.,  wireless  capacity,  professional  services and
               Internet connectivity) through its sales channel.

          (b)  Williams-Provided  Roof Rights and Building Access.  If requested
               by  WinStar,  Williams  shall  grant  to  WinStar,  at  no  cost,
               appropriate  roof,  riser,  conduit rights and interior space (in
               each  case,  in  quantities  to  be  mutually  agreed  upon  on a
               case-by-case  basis) rights to buildings in the United States for
               which  Williams  owns,  leases or occupies,  in whole or in part,
               that Williams can obtain (at reasonable cost) or has such rights.
               In  addition,  Williams  shall assist  WinStar in obtaining  such
               rights  with  respect to other  buildings  in the  United  States
               leased  or  occupied,  in whole or in part,  by  Williams  or its
               Affiliates,  including by actively  conveying to those Affiliates
               the  strategic  and  important  nature of the  relationship  with
               WinStar.  Williams  shall  provide  (and  periodically  update as
               reasonably  requested by WinStar)  WinStar with a written list of
               the addresses of all such real estate.

          (c)  Mutual   Marketing   Support.   WinStar  will  provide   Williams
               reasonable marketing support in connection with Williams' sale of
               the Williams T-1s and other WinStar voice and data products.

          (d)  Provisioning  and Billing OSS. The Parties will work  together in
               order to interface their  then-current  provisioning  and billing
               operational support system information (e.g.,  network events and
               statistics).   The  reasonable   costs   associated   with  these
               activities  shall be mutually  shared  between the  Parties.  If,
               after consultation with Williams,  WinStar is required to provide
               provisioning   and  billing   information   unique  to  Williams'
               wholesale  activities,  the  reasonable  costs of providing  such
               information shall be borne by Williams.

          (e)  Regulatory  Assistance.  If either  Party  affirmatively  takes a
               position in the domestic  regulatory  environment,  it will be in
               favor of a level playing field and in support of competition,  as
               such Party determines in its sole  discretion.  The Parties shall
               periodically (but at least  semi-annually)  meet to discuss their
               plans and objectives with respect to the regulatory environment.

3.  GRANTS, RIGHTS AND RESPONSIBILITIES

     3.1.     WinStar Grant, Rights and Responsibilities.

          (a)  Effective as of the  Acceptance  Date,  WinStar  hereby grants to
               Williams an exclusive  Indefeasible  Right of Use (the  "Williams
               IRU"),  for  the  purposes  described  herein,  in  the  Williams

 

<PAGE>

                                     5

               Connectivity  as  expressed  in  T-1  increments  over  time,  as
               provided in Exhibit  A-6 (the  "Williams  T-1s"),  subject to the
               additional  limitations  set forth in Subsection (c) below.  Such
               grant  does not convey  any legal  title to any real or  personal
               property,   including  the  spectrum,   physical   equipment  and
               connections used to effect the Domestic Hub Capacity.

          (b)  Subject  to the  terms of this  Agreement,  Williams  shall  have
               exclusive use of the Williams T-1s for any lawful  purpose during
               the Term.

          (c)  In addition to the Williams Connectivity  limitation set forth in
               Section  3.1(a),  the  Williams  T-1s  shall  be  subject  to the
               following limitations:

               (i)  Williams T-1s from any Lit Building that is connected to the
                    WinStar Hub through a point-to-point radio link may go up to
                    but shall not exceed _______  percent (__%) of the bandwidth
                    capacity provided to that building notwithstanding WinStar's
                    usage of any or all of such capacity in that building.

               (ii) Williams   T-1s   that   are   to   be   implemented   using
                    point-to-multipoint  links between Lit Buildings in a Sector
                    and a WinStar Hub may go up to but shall not exceed  _______
                    percent  (__%) of the relevant  Sector  Capacity of that Hub
                    notwithstanding WinStar's usage of any or all of such Sector
                    Capacity in the Sector.

               (iii)For Qualified  Buildings lit at Williams'  expense  pursuant
                    to  Section   3.4(b)(ii),   the   limitation  set  forth  in
                    Subsection  (c)(i),  if  applicable,  shall be  increased to
                    _____ percent (__%) for  buildings  lit  point-to-point.  In
                    addition,  only  ____________  percent (__%) of the Williams
                    T-1s in such  buildings  will  count  towards  the  Williams
                    Connectivity limitation set forth in Subsection (a) above.

               (iv) In  accordance  with  Section 3.6,  each  Williams T-1 shall
                    count  against the  limitations  set forth above for ___ (_)
                    ____,  regardless  of  whether  or not the  duration  of its
                    connectivity  lasts less than ___ (_) ____.  After its _____
                    ____ of connectivity,  each Williams T-1 shall count against
                    such limitations until disconnected.

               (v)  Williams may order Williams  Connectivity  only in multiples
                    of T-1 line speeds.  Orders for line speeds  higher than T-1
                    will count proportionately  toward the limitations set forth
                    in this  Subsection  (c). For example,  a DS-3 will count as
                    ____________  (__) T-1s. Apart from the applicability of the
                    limitations,  the line speeds of the  circuits  constituting
                    the  Williams  Connectivity  shall  have  no  effect  on the
                    respective rights and obligations of the Parties.

     3.2. WinStar Acceptance and Testing.

          (a)  As of the Effective Date,  Williams hereby agrees that Acceptance
               of  the  initial  fifty-seven  (57)  Hubs  (the  "Initial  Hubs")
               deployed  by  WinStar  is  deemed  to  have   occurred.   WinStar
               represents  and  warrants  that  the  Initial  Hubs  have met the
               Acceptance Standards as of the Effective Date.


                                       6
<PAGE>

          (b)  Prior to the use of each Hub  deployed by WinStar  following  the
               Effective Date, WinStar will have performed testing procedures in
               accordance  with  Exhibit  A-4,  which are  sufficient  to verify
               compliance with Acceptance Standards. Acceptance of each such Hub
               shall occur as set forth in Exhibit A-4.

     3.3. Control of Facilities.

          Notwithstanding any other provision of this Agreement, WinStar has and
          shall at all times  continue to retain  control over all FCC licenses,
          equipment and facilities  subject to this Agreement and shall have, at
          all times,  required  access to all of the  equipment  and  facilities
          installed  by it  pursuant  to  this  Agreement.  In  exercising  this
          control,  WinStar will not disturb or interfere with the Williams T-1s
          without  good  cause,  such as a  request  from  the FCC to shut  down
          interfering transmissions, emergency service restoration or correction
          of other technical  problems.  WinStar shall provide  Williams with as
          much  prior  notice  as is  reasonably  practicable  in  the  case  of
          emergency  disruptions  of the Wireless  Fiber  Connectivity.  WinStar
          shall, with the reasonable cooperation and assistance of Williams, (i)
          operate its business in all material  respects in accordance  with the
          terms  of  the  Governmental  Authorizations  and  (ii)  maintain  the
          validity of the Governmental Authorizations. WinStar agrees to provide
          Williams with notice in the event matters come to WinStar's  attention
          that could  materially  prevent it from meeting its obligations  under
          this Agreement.  In this regard, WinStar and Williams further agree as
          follows:

          (a)  Williams  shall not  represent  itself  as the  holder of any FCC
               licenses issued to WinStar.

          (b)  Any  communications  by either Party with the FCC  regarding  the
               subject matter of this Agreement  shall require the other's prior
               written approval.

          (c)  Neither WinStar nor Williams shall represent  itself as the legal
               representative   of  the  other  before  the  FCC  or  any  state
               regulatory body. Except as otherwise required by law, all filings
               made before  regulatory  bodies with respect to WinStar's license
               or the services  provided  hereunder  shall be made by and in the
               name of WinStar.  WinStar and Williams will  cooperate  with each
               other with respect to  regulatory  matters  concerning  WinStar's
               licenses and the services  provided  pursuant to this  Agreement;
               provided,  however,  this will not relieve WinStar from complying
               with the Governmental Authorizations.

          (d)  Nothing in this  Agreement  is  intended  to diminish or restrict
               WinStar's  obligations as an FCC licensee and both Parties desire
               that  this  Agreement  be in full  compliance  with the rules and
               regulations  of the FCC and any state or local  jurisdiction.  If
               the FCC or any state  regulatory  body of competent  jurisdiction
               determines  that any  provision  of this  Agreement  violates any
               applicable  rules,  policies or  regulations,  both Parties shall
               bear  their  respective  Pro Rata  Share of costs to  immediately
               bring this Agreement into compliance,  consistent with the intent
               of this Agreement.

          (e)  It is expressly  understood  by WinStar and Williams that nothing
               in this  Agreement is intended to give to Williams any right that
               would be deemed to constitute a transfer of control (as "control"
               is defined in the Communications Act of 1934, as amended,  or any
               applicable  FCC  rules or case  law) of one or more of  WinStar's
               licenses from WinStar to Williams.


                                       7
<PAGE>

     3.4. Provisioning of Williams T-1s.

          Except as otherwise provided in this Section 3.4, WinStar,  at its own
          expense, shall be solely responsible for obtaining and maintaining all
          rights and privileges  (including  Required  Rights,  space and power)
          that are  necessary  for WinStar to provide the  Williams  T-1s to the
          WinStar common space.

          (a)  Subject to the limitations set forth in Section 3.1, Williams may
               order  T-1s  to be  connected  to any  Qualified  Building  (or a
               building that would be a Qualified Building but for the obtaining
               of Required Rights). If Williams orders Williams T-1s that are to
               be connected to a Lit  Building,  WinStar  will  provision,  on a
               non-discriminatory  basis,  those T-1s to the common  space at no
               additional cost with an objective of completing that provisioning
               within ______ (__) days from the date of Williams' order.

          (b)  If Williams  orders  Williams  T-1s that are to be connected to a
               Qualified  Building  (or a  building  that  would be a  Qualified
               Building but for the obtaining of Required  Rights) that is not a
               Lit Building:

               (i)  WinStar shall  determine  within ______ (__) days of receipt
                    of notice from Williams whether, in its sole discretion,  it
                    will light such  building at its own expense.  If WinStar so
                    elects,  that notice shall set forth a target  delivery date
                    and WinStar  shall light that building and  provision,  on a
                    non-discriminatory  basis, the T-1s to the common space with
                    the  objective of completing  such  activities by the target
                    delivery date.

               (ii) If  WinStar  elects not to light  such  building  at its own
                    expense,  WinStar  will light the  building  upon  Williams'
                    request,   in  accordance   with  a  target   delivery  date
                    established by WinStar. Williams shall pay for such lighting
                    at  WinStar's  Cost of  performance.  Additionally,  in such
                    event,   Williams  shall  be  responsible,   with  WinStar's
                    assistance,  for  obtaining  and  maintaining,  at Williams'
                    expense,  all  necessary  rights and  privileges  (including
                    Required  Rights,  space and power).  Lighting,  pursuant to
                    this Subsection 3.4(b)(ii),  of more than ____ (_) buildings
                    connected to a single Hub,  whether singly or in combination
                    over any  period  of time,  shall be  subject  to  WinStar's
                    approval which shall not be unreasonably withheld.

          (c)  When WinStar  lights a building for  provisioning a Williams T-1,
               Williams will either:

               (i)  Perform  inside  wiring for its  customers in such  building
                    subject  both to  obtaining  any  necessary  consents and to
                    WinStar's   then-current    installation    guidelines   and
                    specifications; or

               (ii) Have WinStar perform such wiring at WinStar's Cost.

                                       8
<PAGE>

     3.5. Service Orders for Williams T-1s.

          (a)  The  implementation  of a Williams T-1 to a Lit Building shall be
               requested on WinStar's Service Order forms in effect from time to
               time ("Service Orders").  Each Service Order shall reference this
               Agreement.  WinStar  reserves  the  right not to accept a Service
               Order that does not conform with the terms and conditions of this
               Agreement  and such  non-conforming  Service  Order shall have no
               force or effect hereunder.

          (b)  Each  Service  Order will  indicate a  requested  Start Date (the
               "Requested  Start Date") for the  implementation  of the Williams
               T-1s to a Lit  Building,  the desired term of the Williams  T-1s,
               and any other  parameters  required.  WinStar  shall  acknowledge
               receipt of the Service Order, on average, within forty-eight (48)
               hours (an "Acknowledgement").

          (c)  Once a Service  Order is placed,  Williams  may cancel it only by
               notice  of  cancellation  not less  then ___ (__)  days  prior to
               delivery of the  corresponding  Williams  T-1, and payment of any
               specified  cancellation  fee.  Williams  agrees  that the  actual
               damages in the event of such  cancellation  would be difficult or
               impossible  to  ascertain,   and  that  the  cancellation  charge
               including  those set forth  herein is  consequently  intended  to
               establish liquidated damages and not a penalty.

          (d)  Any  conflicting,  different or additional  terms and  conditions
               contained  in  Williams'   acknowledgment  or  Service  Order  or
               elsewhere  are  deemed  objected  to by  WinStar  and  shall  not
               constitute  part  of  this   Agreement.   No  action  by  WinStar
               (including  fulfillment of such Service Order) shall be construed
               as binding or estopping WinStar with respect to such conflicting,
               different or  additional  term or  condition,  unless the Service
               Order  containing  said term or  condition  has been signed by an
               authorized representative of WinStar.

          (e)  WinStar  shall make  reasonable  efforts to provide the  Williams
               T-1s  within the  service  implementation  interval  set forth in
               Section  3.5(b) or by Williams'  Requested  Start Date.  Williams
               T-1s shall begin on the date WinStar  issues  notice that service
               is  available   (the  "Start  of  Service   Notice"  or  "SOSN"),
               indicating  the  Williams  T-1 has  been  tested  by  WinStar  in
               accordance with WinStar's  standard  specifications  and that the
               service meets or exceeds those specifications.

          (f)  Williams  may  reasonably  request  one  or  more  delays  in the
               Requested Start Date of a Service Order, a move, or rearrangement
               if WinStar  receives the delay request at least _______ (__) days
               prior to the Requested  Start Date and the  requested  delay does
               not extend the  Requested  Start Date more than _______ (__) days
               from the original date thereof.  If Williams delays the Requested
               Start Date (or as gauged by the SOSN,  if issued for a date after
               the  Requested  Start Date) by more than  ______  (__) days,  the
               Williams  T-1s  will  count  against  the  Minimum  Williams  T-1
               Inventory and the Williams  Connectivity  for a period of one (1)
               year.  This count against the Minimum  Williams T-1 Inventory and
               Williams  Connectivity  will be effective  ______ (__) days after
               the Requested Start Date.


                                       9
<PAGE>

     3.6. Changes in Service Parameters.

          Following the relevant  Start Date for any Williams T-1,  Williams may
          disconnect  or  reconfigure  that  service upon sixty (60) days' prior
          written notice.  If that action relates to a Williams T-1 that has not
          been in place for at least one (1) year from its Start Date,  (i) such
          Williams T-1 will continue to count  against the Minimum  Williams T-1
          Inventory and Williams  Connectivity  for the remainder of the one (1)
          year period;  and (ii) Williams  shall also pay WinStar the additional
          charges   incurred   by  WinStar   that  are   associated   with  that
          disconnection  or  reconfiguration.  Subsection  (ii) shall also apply
          with respect to a cancellation as provided in Section 3.5(c).

     3.7. Delivery of Minimum Williams T-1 Inventory.

          (a)  Availability  Date.  The  "Availability  Date" shall mean (i) the
               Effective Date with respect to the Minimum Williams T-1 Inventory
               identified  in Exhibit  A-6 to be  provided to Williams as of the
               Effective  Date,  and (ii)  December  31st of each  calendar year
               following  1998  through the end of the Term with respect to each
               annual  number of Minimum  Williams T-1  Inventory  identified in
               Exhibit A-6 for such calendar year. The "Deadline  Date" shall be
               sixty (60) days after the later of (i) such planned  Availability
               Date or (ii) the planned  Availability  Date as  extended  due to
               unforeseen events not in the reasonable control of WinStar (other
               than as due to WinStar's negligence),  Force Majeure events or as
               expressly  permitted  by  this  Agreement.   WinStar  shall  make
               available each of its annual Minimum  Williams T-1 Inventories by
               the applicable Deadline Date. WinStar shall give Williams as much
               prior notice as reasonably  possible if, to the best of WinStar's
               knowledge,  there  is a  foreseeable  risk  that  it  may  miss a
               Deadline Date for its Minimum Williams T-1 Inventory.

          (b)  Failure to Meet Deadline Date. If WinStar fails to make available
               the Minimum  Williams T-1  Inventory by its  applicable  Deadline
               Date, and the Parties are unable,  in good faith,  to agree to an
               alternative  Deadline Date, Williams' sole and exclusive monetary
               remedy for such failure shall be to obtain Cover (as  hereinafter
               defined)  beginning on the  Deadline  Date for the number of T-1s
               not made available.  "Cover" shall be satisfied by obtaining,  at
               WinStar's  expense,  the  number  of T-1s  that  would  have been
               available  had  WinStar  made  available  the  entire  applicable
               Minimum  Williams T-1  Inventory.  Once  WinStar  makes such T-1s
               available,  the Parties will work together to migrate the T-1s to
               WinStar at WinStar's sole cost and expense.

4.       OTHER PERFORMANCE AND SERVICES

     4.1.     Interconnection.

          (a)  With respect to each of the WinStar Target  Markets,  the Parties
               shall mutually  determine the most efficient  manner of providing
               the required connectivity ("Interconnection") between the WinStar
               and Williams points of presence,  whether  through  then-existing
               installed capacity, implementation of new capacity or third party
               arrangements. In addition, the Parties shall set and periodically
               review the schedule  (timing and priority) of  implementation  of
               those  Interconnection   facilities  and  shall  adhere  to  that
               schedule in implementing such facilities.


                                       10
<PAGE>

          (b)  The  Parties  shall  allocate  the costs of each  Interconnection
               facility as follows:

               (i)  The  Parties  shall  mutually  agree upon a forecast of each
                    Party's usage of that  Interconnection  facility  during the
                    first  year  after  implementation  (the  "Forecast").   The
                    non-recurring  costs associated with the  implementation  of
                    that  facility and the  recurring  cost thereof in the first
                    month of operation (in aggregate, the "Start-up Costs") will
                    be  allocated  pro rata  between the Parties  based upon the
                    Forecast. One year thereafter the Parties shall re-calculate
                    the allocation of the Start-up Costs by substituting  actual
                    usage during the  preceding  year in place of the  Forecast.
                    Based upon that recalculation, Williams shall pay or receive
                    a refund, in either case equal to the difference between the
                    initial   allocation   of  the   Start-up   Costs   and  the
                    recalculated amount, plus interest at the Prime Rate for the
                    applicable period.

               (ii) On  a  quarterly  basis,  the  Parties  shall  allocate  the
                    periodic  recurring costs of that  Interconnection  facility
                    pro rata between the Parties  based upon actual usage during
                    the preceding quarter.

               (iii)Following  the  Effective  Date,  the Parties will  mutually
                    develop appropriate procedures to implement the foregoing.

     4.2. Collocation.

          Exhibit A-3 sets forth the collocation services, terms and conditions.

     4.3. Maintenance.

          WinStar shall be  responsible  for providing  maintenance,  repair and
          testing on all WinStar Equipment used to provide the Williams T-1s, in
          accordance with its then-current  standard policies and procedures,  a
          portion  of which is  attached  hereto as  Exhibit  A-4.  Williams  is
          prohibited  from  providing  any  maintenance,  repair or testing with
          regard to WinStar Equipment.

     4.4. Routine Maintenance.

          During  the  Term,   WinStar  shall   perform  all  required   Routine
          Maintenance  Services at the charges set forth in Schedule C. "Routine
          Maintenance  Services"  means  the  work  specifically  identified  as
          Routine Maintenance Services in Article 5 of Schedule A, provided that
          Routine  Maintenance  Services  excludes  work for which  Williams  is
          obligated  to  reimburse  WinStar  for all or a  portion  of the Costs
          incurred pursuant to other provisions of this Agreement.

     4.5. Non-Routine Maintenance.

          Williams  shall pay its Pro Rata Share of  WinStar's  direct Costs for
          maintenance in respect of the Williams Connectivity other than Routine
          Maintenance  Services, if the Cost of such work relating to any single
          event or multiple related events is greater than Five Thousand Dollars
          ($5,000.00).

                                       11
<PAGE>

     4.6. Subcontractors.

          WinStar may subcontract provisioning,  testing,  maintenance,  repair,
          restoration, relocation or other operational and technical services it
          is obligated to provide hereunder or may have the underlying  facility
          owner or its contractor perform such obligations.  Such subcontracting
          shall not relieve WinStar of any obligations under this Agreement.
     
     4.7. Williams Equipment.

          WinStar's  maintenance  and repair  obligations  under this  Agreement
          shall not include  maintenance,  repair or  replacement  of  Williams'
          equipment.

     4.8. Performance Standards.

          Except as  otherwise  set forth in Schedule B, for the purpose of this
          Agreement   the   normal   standards   of   performance   within   the
          telecommunications  industry  in  the  relevant  market  shall  be the
          measure of whether a Party's performance is reasonable and timely.

     4.9. Disengagement Assistance.

          Upon  termination  or  expiration  of this  Agreement,  WinStar  shall
          provide   Williams  and  its  designated  third  party  providers  all
          reasonable  assistance as necessary to effect a smooth transition to a
          new supplier.

     4.10. Relocation.

          (a)  If WinStar  determines for bona fide operational  reasons,  or is
               required by a third party  acting  pursuant  to  condemnation  or
               similar authority or by a governmental entity, to relocate all or
               any portion of a Hub or any of the facilities used or required in
               providing  Williams with the Williams IRU,  WinStar shall, to the
               extent  practicable,  provide  Williams  sixty (60)  days'  prior
               notice and shall proceed with such relocation. WinStar shall have
               the  right to  direct  such  relocation,  including  the right to
               determine  the extent  of, the timing of, and  methods to be used
               for such relocation, provided that any such relocation:

               (i)  Shall be  constructed  and  tested  in  accordance  with the
                    specifications  and requirements set forth in this Agreement
                    and applicable Exhibits;

               (ii) Shall  not  result  in a  materially  adverse  change to the
                    operations or performance of the Hub, and

               (iii) Shall not unreasonably interrupt service on the Hub.

               For purposes of this Section 4.10, a WinStar  relocation shall be
               for bona fide  operational  reasons if it is  undertaken  in good
               faith  (i) to settle  or avoid a bona  fide  threatened  or filed
               condemnation  action  or order  by a  governmental  authority  to
               relocate, (ii) to reduce the likelihood of physical damage, (iii)
               as the  result  of a  Force  Majeure  Event,  or (iv)  for  other
               operational  reasons to which  Williams has  consented,  provided
               that  Williams  shall not  unreasonably  withhold  such  consent.
               WinStar shall use  reasonable  efforts to contest any exercise of
               condemnation  authority that would require a relocation  pursuant
               to this Section 4.10.

                                       12
<PAGE>

          (b)  Unless such  relocation is  necessitated by a breach of WinStar's
               obligations  under  this  Agreement,   Williams  shall  reimburse
               WinStar for the Costs incurred in the same manner and to the same
               extent as set forth for  reimbursement  for Costs of  maintenance
               other than for Routine Maintenance Services in Section 4.5.

     4.11. Ancillary Services.

          WinStar  may also  provide  other  services  to  Williams  for reasons
          including: (a) Williams' request to expedite Williams T-1 availability
          to a date earlier than WinStar's published  installation interval or a
          previously  accepted  Start Date;  (b)  Williams T-1 redesign or other
          activity   occasioned  by  receipt  of  inaccurate   information  from
          Williams; (c) Williams' request for use of facilities other than those
          selected by WinStar for provision of the Wireless  Fiber  Connectivity
          ("facilities" for this purpose shall not include buildings that became
          Lit  Buildings   pursuant  to  Section   3.4(b)(i));   and  (d)  other
          circumstances in which  extraordinary costs and expenses are generated
          at  the  written   request  of  Williams   and   incurred  by  WinStar
          (collectively, "Ancillary Services").

5.  CONTRACT ADMINISTRATION

     5.1. Reports and Meetings.

          (a)  Within thirty (30) days of the Effective  Date, the Parties shall
               mutually  agree  upon a set of  monthly  reports  to be issued by
               WinStar to Williams. WinStar will provide Williams with suggested
               formats for such reports for Williams'  review and  approval.  As
               one such  report,  WinStar  will  provide a  monthly  performance
               report  that   describes   WinStar's   deployment  of  the  Hubs,
               availability of the applicable Minimum Williams T-1 Inventory and
               a forecast  of upcoming  WinStar  Target  Market  implementations
               (including Hubs, buildings and addresses).

          (b)  Within thirty (30) days of the Effective  Date, the Parties shall
               mutually agree upon a set of regular management meetings. WinStar
               will prepare and circulate an agenda  sufficiently  in advance of
               each such meeting to give  participants an opportunity to prepare
               for the meeting and will  incorporate  into such agenda any items
               that Williams desires to discuss.  At Williams' request,  WinStar
               will prepare and circulate minutes promptly after a meeting.

     5.2. Confidentiality.

          (a)  Confidential  Information.  Williams and WinStar each acknowledge
               that they may be furnished with, receive or otherwise have access
               to  information  of or concerning the other Party that such Party
               considers  to be  confidential,  proprietary,  a trade  secret or
               otherwise  restricted.  As used in this  Agreement and subject to
               Section (c), "Confidential Information" means all information, in
               any form,  furnished or made available  directly or indirectly by
               one Party (the  "Disclosing  Party") to the other (the "Receiving
               Party")  that (i)  concerns the  operations,  facilities,  plans,
               affairs and  businesses of the  Disclosing  Party,  the financial
               affairs  of  the  Disclosing  Party,  and  the  relations  of the
               Disclosing  Party  with  its  customers,  employees  and  service
               providers,   or  (ii)   is   marked   confidential,   restricted,


                                       13

<PAGE>


               proprietary,  or  with  a  similar  designation.  The  terms  and
               conditions  of  this  Agreement  shall  be  deemed   Confidential
               Information, but may be disclosed pursuant to this Section 5.2 or
               Section 12.15.

          (b)  Obligations.

               (i)  Each  Party's  Confidential  Information  shall  remain  the
                    property  of  that  Party  except  as   expressly   provided
                    otherwise by the other  provisions of this  Agreement.  Each
                    Party shall each use at least the same  degree of care,  but
                    in any event no less than a  reasonable  degree of care,  to
                    prevent unauthorized disclosure of Confidential  Information
                    as it employs to avoid  unauthorized  disclosure  of its own
                    information  of  a  similar  nature.   Except  as  otherwise
                    permitted   hereunder,   the  Parties  may   disclose   such
                    information  (A) to their  respective  directors,  officers,
                    managers,  employees,  agents,  contractors  and consultants
                    (collectively,    "Representatives"),    (B)   to   entities
                    performing  services required  hereunder only where: (1) use
                    of such entity is authorized under this Agreement,  (2) such
                    disclosure  is necessary or  otherwise  naturally  occurs in
                    that entity's scope of responsibility, (3) the entity agrees
                    in  writing  to assume  the  obligations  described  in this
                    Subsection (b). Any disclosure to such entity shall be under
                    substantially the same confidentiality  terms and conditions
                    set forth herein.

               (ii) Each Party  shall take  reasonable  steps to ensure that its
                    (and  its  Affiliates')  Representatives  comply  with  this
                    Subsection  (b). In the event of any  disclosure or loss of,
                    or inability to account for, any Confidential Information of
                    the Disclosing Party, the Receiving Party shall promptly, at
                    its own expense: (A) notify the Disclosing Party in writing;
                    and (B) take such actions as may be necessary  and cooperate
                    in all  reasonable  respects  with the  Disclosing  Party to
                    minimize the violation and any damage resulting therefrom.

               (iii)Either Party may disclose the terms and  conditions  of this
                    Agreement  to any third party that (A) has  expressed a bona
                    fide  interest  in  consummating  a  significant  financing,
                    merger or acquisition or other corporate transaction between
                    such  third  party  and  such  Party,  (B) has a  reasonable
                    ability   (financial  and  otherwise)  to  consummate   such
                    transaction,  and (C) has executed a nondisclosure agreement
                    that includes  within its scope the terms and  conditions of
                    this  Agreement  and also  includes a procedure to limit the
                    extent of copying and distribution thereof. Each Party shall
                    endeavor to delay the disclosure of the terms and conditions
                    of this Agreement until the status of discussions concerning
                    such  transaction  warrants  such  disclosure.  In addition,
                    either party (or either party's Affiliates) may disclose the
                    terms and  conditions of this  Agreement as such party deems
                    appropriate   to  prepare   for  IPOs  or  major   corporate
                    transactions.   Any  disclosure  to  such  entity  shall  be
                    substantially  under  the  same  confidentiality  terms  and
                    conditions as provided herein.

                                       14
<PAGE>

          (c)  Exclusions.   "Confidential   Information"   shall   exclude  any
               particular information that the Receiving Party can demonstrate:

               (i)  At the time of  disclosure,  was in the public  domain or in
                    the rightful possession of the Receiving Party;

               (ii) After disclosure,  is published or otherwise becomes part of
                    the public domain through no fault of the Receiving Party;

               (iii)Was received after  disclosure  from a third party who had a
                    lawful right to disclose such  information  to the Receiving
                    Party without any  obligation to restrict its further use or
                    disclosure;

               (iv) Was  independently  developed by the Receiving Party without
                    reference  to  Confidential  Information  of the  Disclosing
                    Party; or

               (v)  Was required to be disclosed to satisfy a legal  requirement
                    of a competent  government body; provided that,  immediately
                    upon  receiving  such  request and to the extent that it may
                    legally do so, the Receiving  Party  advises the  Disclosing
                    Party promptly and prior to making such  disclosure in order
                    that the Disclosing Party may interpose an objection to such
                    disclosure,  take action to assure confidential  handling of
                    the Confidential  Information,  or take such other action as
                    it   deems   appropriate   to   protect   the   Confidential
                    Information.

          (d)  No Implied  Rights.  Nothing  contained in this Section  shall be
               construed  as  obligating  a Party to disclose  its  Confidential
               Information  to the other Party,  or as granting to or conferring
               on a Party, expressly or impliedly,  any rights or license to the
               Confidential Information of the other Party.

6.   CHARGES

     6.1. General.

          The charging  mechanisms and pricing  methodologies for Wireless Fiber
          Connectivity and maintenance and collocation services are set forth in
          Schedule C. 

     6.2. Taxes.

          The Parties' respective responsibilities for taxes arising under or in
          connection with this Agreement shall be as follows:

          (a)  Each Party shall be  responsible  for personal  property taxes on
               property it owns or leases,  for franchise and privilege taxes on
               its  business,  and for  taxes  based on its net  income or gross
               receipts;  provided,  however, that Williams shall be responsible
               for its proportionate share (based upon the proportion of the Hub
               or building capacity used for Williams T-1) of any property taxes
               (or similar levies) assessed as a result of the implementation of
               any Williams T-1.


                                       15
<PAGE>

          (b)  Williams  shall  timely  report and pay any and all  sales,  use,
               income,  gross receipts,  excise,  transfer,  ad valorem or other
               taxes,  and any and all  franchise  fees or similar fees assessed
               against  it due to the  Williams  IRU or its use of the  Williams
               T-1s.

          (c)  If a sales, use, excise, value-added,  services,  consumption, or
               other tax is  assessed on the  provision  of the  Wireless  Fiber
               Connectivity,  Maintenance  or any other  services,  the  Parties
               shall  work  together  to  segregate  the  payments   under  this
               Agreement into three (3) payment streams:

               (i)  Payments for taxable items;

               (ii) Payments where Williams  functions merely as a payment agent
                    for WinStar; and

               (iii) Payments for other nontaxable items.

          (d)  The Parties agree to cooperate  with each other to enable each to
               determine  more  accurately its own tax liability and to minimize
               such  liability to the extent legally  permissible.  Each invoice
               shall separately  state the amounts of any taxes collected.  Each
               Party shall  provide and make  available  to the other any resale
               certificates  and other  exemption  certificates  or  information
               reasonably  requested by either Party that is  applicable  to the
               subject matter of this Agreement.

          (e)  Each Party shall promptly notify the other of, and coordinate the
               response to and  settlement  of, any claim for taxes  asserted by
               applicable  taxing  authorities  for  which  the  other  Party is
               responsible hereunder. With respect to any claim arising out of a
               form or return  signed by a Party to this  Agreement,  such Party
               shall  have the right to elect to  control  the  response  to and
               settlement  of the  claim,  but the other  Party  shall  have all
               rights to participate in the responses and  settlements  that are
               appropriate to its potential responsibilities or liabilities.

     6.3. Pass-Through Expenses.

          For each  Pass-Through  Expense,  if any,  WinStar  shall  review  the
          invoiced  charges and  determine  whether  such charges are proper and
          valid.  Unless the  Parties  mutually  agree  otherwise,  Pass-Through
          Expenses will be paid directly by Williams.

     6.4. Most Favored Customer Status.

          (a)  Williams T-1s. With regard to the Williams Connectivity, Williams
               shall have most favored customer protection as follows:

               (i)  ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________

                                       16
<PAGE>


                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________

               (ii) ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________


          (b)  Excess  Connectivity.  With regard to Wireless Fiber Connectivity
               in excess of the Williams  Connectivity  or Williams T-1 Ceiling,
               as appropriate ("Excess Connectivity"),  Williams shall have most
               favored customer protection as follows:

               (i)  ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________

               (ii) ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________
                    ____________________________________________________________


                                       17
<PAGE>

     6.5. Benchmarking.

          (a)  Wireless Fiber  Connectivity  offered by WinStar in excess of the
               Williams  Connectivity,  if any, shall be of equivalent or better
               quality,   availability   and  price  when  compared  to  similar
               offerings in the  marketplace.  However,  nothing in this Section
               6.5 shall be  deemed to  require  WinStar  to sell more  Wireless
               Fiber Connectivity than the Williams Connectivity.

          (b)  Within  180 days  after the  Effective  Date,  the  Parties  will
               jointly  establish  a  benchmarking  measurement  and  comparison
               process  (the  "Benchmarking  Process")  designed to  objectively
               evaluate  whether the Wireless  Fiber  Connectivity  purchased by
               Williams in excess of the Williams  Connectivity is of equivalent
               or better quality,  availability and price as compared to similar
               services  generally  available in the market for similar size and
               scope  requirements  ("Market Level  Charges").  The Benchmarking
               Process  will take into  consideration  relevant  factors such as
               quality and delivery terms.

7.       INVOICING AND PAYMENT

     7.1. Invoicing.

          WinStar  shall  invoice  Williams  for  all  amounts  due  under  this
          Agreement  prior to the payment dates set forth in Schedule C and on a
          monthly  basis in arrears for all other  charges.  Each invoice  shall
          show such details as  reasonably  requested  by  Williams,  separately
          state the amounts of any taxes collected and include the  calculations
          utilized to establish the charges.

     7.2. Payment Due.

          (a)  Subject  to the other  provisions  of this  Article  7,  invoices
               provided for under Section 7.1 and properly submitted to Williams
               pursuant to this  Agreement  shall be due and payable by Williams
               within  thirty (30) days after  receipt  thereof.  Any amount due
               under  this  Agreement  for  which  a  time  for  payment  is not
               otherwise  specified  shall be due and payable within thirty (30)
               days after receipt of a proper invoice for such amount.

          (b)  To the  extent  a credit  may be due  Williams  pursuant  to this
               Agreement,  WinStar  shall provide  Williams with an  appropriate
               credit against amounts then due and owing; if no further payments
               are due to WinStar,  WinStar  shall pay such  amounts to Williams
               within thirty (30) days.

          (c)  Williams shall make payments provided for under this Article 7 or
               Schedule C by wire transfer of immediately available funds to the
               account or accounts designated by WinStar.  All other payments to
               be made pursuant to this  Agreement may be made by check or draft
               of  immediately   available   funds   delivered  to  the  address
               designated in writing by the other Party (e.g., in a statement or
               invoice) or, failing such designation,  to the address for notice
               to such other Party provided pursuant to Section 12.8.

          (d)  The first invoice  provided under this Agreement shall be due and
               payable within sixty (60) days of the Effective Date.

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<PAGE>

     7.3. Disputed Charges.

          Williams shall pay undisputed charges when such payments are due under
          this Agreement.  Williams may withhold  payment of particular  charges
          that Williams  disputes in good faith and for which it promptly  gives
          written  notice to WinStar,  stating the details of such dispute.  The
          Parties  shall  promptly  refer such matter to dispute  resolution  in
          accordance  with  Section  11.2.  If Williams  withholds  any disputed
          charges and such charges are  ultimately  determined  to be proper and
          payable to WinStar,  Williams  shall pay such  charges to WinStar plus
          interest at the Prime Rate from the date such charges were  originally
          due until the date such  charges  are  paid.  WinStar  agrees  that no
          payment  dispute  shall be grounds for WinStar to withhold or diminish
          the  quality  or  quantity  of any of the  connectivity  and  services
          provided hereunder.

     7.4. Late Interest.

          If either  Williams or WinStar  fails to make any  payment  under this
          Agreement when due, such amounts shall accrue interest,  from the date
          such payment is due until paid,  including  accrued  interest,  at the
          Prime Rate.

8.   COVENANTS, REPRESENTATIONS AND WARRANTIES

     8.1. Non-Infringement.

          Each Party  represents,  warrants  and  covenants to the other that it
          shall perform its  responsibilities  under this  Agreement in a manner
          that  does  not   infringe,   or   constitute   an   infringement   or
          misappropriation  of, any  Intellectual  Property  Rights of any third
          party.

     8.2. Authorization.

          Each Party represents and warrants to the other that:

          (a)  It has the requisite  corporate power and authority to enter into
               this Agreement and to carry out the transactions  contemplated by
               this Agreement;

          (b)  The execution, delivery and performance of this Agreement and the
               consummation of the  transactions  contemplated by this Agreement
               have been duly  authorized by the requisite  corporate  action on
               the part of such Party;

          (c)  This Agreement  constitutes a legal, valid and binding obligation
               enforceable against such party in accordance with its terms;

          (d)  Its execution of and  performance  under this Agreement shall not
               violate any applicable existing regulations,  rules, statutes, or
               court orders of any local,  state, or federal  government agency,
               court, or body;

          (e)  It is not subject to any  contractual  or other  obligation  that
               would prevent it from entering into this relationship; and

          (f)  It has not offered or provided  any  inducements  in violation of
               law or the  other  Party's  policies  of which it has been  given
               notice, in connection with this Agreement.


                                       19
<PAGE>

     8.3. Wireless Fiber Connectivity.

          Excluding  services  provided by third  parties  other than  WinStar's
          subcontractors,  WinStar  covenants  that the  Williams  T-1s shall be
          designed,   engineered,   installed,   constructed   and  operated  in
          accordance  with  the  specifications  set  forth  in  the  applicable
          services  schedule.  WinStar  further  covenants  that it will use its
          commercially  reasonable efforts under the circumstances to remedy any
          delays, interruptions, omissions, mistakes, accidents or errors in the
          Williams T-1s provided  hereunder and to restore such Williams T-1s to
          compliance with the terms hereof.

     8.4. Disclaimer.

          EXCEPT AS SPECIFICALLY  SET FORTH IN THIS AGREEMENT,  THE PARTIES MAKE
          NO  WARRANTY  TO EACH  OTHER OR ANY  OTHER  ENTITY,  WHETHER  EXPRESS,
          IMPLIED OR  STATUTORY,  AS TO THE  MERCHANTABILITY  OR FITNESS FOR ANY
          PARTICULAR PURPOSE OF ANY WIRELESS FIBER CONNECTIVITY,  WILLIAMS T-1s,
          HUBS,  ANCILLARY  SERVICES OR ANY OTHER SERVICES PROVIDED HEREUNDER OR
          DESCRIBED HEREIN,  OR AS TO ANY OTHER MATTER,  ALL OF WHICH WARRANTIES
          ARE HEREBY EXPRESSLY EXCLUDED AND DISCLAIMED.

9.   INDEMNIFICATION

     9.1. Indemnities by Williams.

          Williams agrees to indemnify, defend and hold harmless WinStar and its
          Affiliates  and  their  respective  officers,  directors,   employees,
          agents,   successors,  and  assigns,  from  any  and  all  Losses  and
          threatened  Losses  arising  from,  in  connection  with,  or based on
          allegations of, any of the following:

          (a)  Williams' failure to observe or perform its duties or obligations
               to third parties (e.g., duties or obligations to subcontractors);

          (b)  Williams'  infringement or  misappropriation  of any Intellectual
               Property Rights of any third party;

          (c)  Williams'  unexcused failure to abide by the terms and conditions
               of the business relationship as mutually agreed to by the Parties
               in writing;

          (d)  The death or  bodily  injury of any  agent,  employee,  customer,
               business  invitee or any other person to the extent caused by the
               tortious conduct of Williams;

          (e)  The damage,  loss or destruction of any real or tangible personal
               property  to  the  extent  caused  by  the  tortious  conduct  of
               Williams;

          (f)  Fines,  penalties  or  other  amounts  payable  due to  Williams'
               violation of applicable laws or regulations; and

          (g)  Any claim,  demand,  charge,  action,  cause of action,  or other
               proceeding  asserted against WinStar but resulting from an act or
               omission of Williams in its capacity as an employer of a person.


                                       20
<PAGE>

     9.2. Indemnities by WinStar.

          WinStar agrees to indemnify, defend and hold harmless Williams and its
          Affiliates  and  their  respective  officers,  directors,   employees,
          agents,   successors,  and  assigns,  from  any  and  all  Losses  and
          threatened  Losses  arising  from,  in  connection  with,  or based on
          allegations of, any of the following:

          (a)  WinStar's failure to observe or perform its duties or obligations
               to third parties (e.g., duties or obligations to its customers);

          (b)  WinStar's   infringement  or   misappropriation  of  Intellectual
               Property Rights of any third party;

          (c)  WinStar's  unexcused failure to abide by the terms and conditions
               of the business relationship as mutually agreed to by the Parties
               in writing;

          (d)  The death or  bodily  injury of any  agent,  employee,  customer,
               business  invitee or any other person to the extent caused by the
               tortious conduct of WinStar;

          (e)  The damage,  loss or destruction of any real or tangible personal
               property to the extent caused by the tortious conduct of WinStar;

          (f)  Fines,  penalties  or  other  amounts  payable  due to  WinStar's
               violation of applicable laws or regulation; and

          (g)  Any claim,  demand,  charge,  action,  cause of action,  or other
               proceeding asserted against Williams but resulting from an act or
               omission of WinStar in its capacity as an employer of a person.

     9.3. Indemnification Procedures.

          With respect to third-party  claims,  the following  procedures  shall
          apply:

          (a)  Promptly  after  receipt  of  notice  of  the   commencement   or
               threatened  commencement of any civil, criminal,  administrative,
               or  investigative  action  or  proceeding  involving  a claim  in
               respect  of  which  the  indemnitee  will  seek   indemnification
               pursuant  to this  Article  9, the  indemnitee  will  notify  the
               indemnitor of such claim in writing.  No failure to so notify the
               indemnitor will relieve the indemnitor of its  obligations  under
               this  Agreement  except  to the  extent  that it can  demonstrate
               damages  attributable  to  such  failure.   Within  fifteen  (15)
               calendar  days  following  receipt  of  written  notice  from the
               indemnitee  relating  to any  claim,  but no later  than ten (10)
               calendar  days  before  the  date  on  which  any  response  to a
               complaint  or  summons is due,  the  indemnitor  will  notify the
               indemnitee in writing if the indemnitor  elects to assume control
               of the  defense  and  settlement  of that  claim  (a  "Notice  of
               Election").

          (b)  If the indemnitor  delivers a Notice of Election  relating to any
               claim within the required notice period,  the indemnitor shall be
               entitled to have sole control over the defense and  settlement of
               such claim; provided that (i) the indemnitee shall be entitled to

                                       21
<PAGE>

               participate in the defense of such claim and to employ counsel at
               its own expense to assist in the handling of such claim, and (ii)
               the indemnitor shall obtain the prior written approval, not to be
               unreasonably  withheld  or  delayed,  of  the  indemnitee  before
               entering  into any  settlement of such claim or ceasing to defend
               against such claim.  After the  indemnitor has delivered a Notice
               of  Election  relating  to  any  claim  in  accordance  with  the
               preceding  paragraph,  the indemnitor  shall not be liable to the
               indemnitee for any legal  expenses  incurred by the indemnitee in
               connection  with the  defense of that  claim.  In  addition,  the
               indemnitor  shall not be required to indemnify the indemnitee for
               any amount paid or payable by the indemnitee in the settlement of
               any claim for which the  indemnitor has delivered a timely Notice
               of  Election  if such  amount was agreed to without  the  written
               consent of the indemnitor.

          (c)  If the indemnitor does not deliver a Notice of Election  relating
               to any claim  within the  required  notice  period,  or ceases to
               defend against the claim,  the indemnitee shall have the right to
               defend the claim in such  manner as it may deem  appropriate,  at
               the cost and  expense of the  indemnitor.  The  indemnitor  shall
               promptly   reimburse  the  indemnitee  for  all  such  costs  and
               expenses.

10. LIABILITY, RISK OF LOSS AND INSURANCE

     10.1. General Intent.

          Subject  to the  specific  provisions  of this  Article  10, it is the
          intent of the  Parties  that each  Party  shall be liable to the other
          Party for any actual damages incurred by the non-breaching  Party as a
          result of the breaching  Party's failure to perform its obligations in
          the manner required by this Agreement.

     10.2. Liability Restrictions.

          (a)  IN NO EVENT,  WHETHER IN CONTRACT OR IN TORT (INCLUDING BREACH OF
               WARRANTY, NEGLIGENCE AND STRICT LIABILITY IN TORT), SHALL A PARTY
               BE LIABLE FOR INDIRECT OR CONSEQUENTIAL,  EXEMPLARY,  PUNITIVE OR
               SPECIAL  DAMAGES  EVEN IF SUCH  PARTY  HAS  BEEN  ADVISED  OF THE
               POSSIBILITY OF SUCH DAMAGES IN ADVANCE.

          (b)  Subject to Subsection (c), below, each Party's total liability to
               the other,  whether in contract or in tort  (including  breach of
               warranty,  negligence  and  strict  liability  in tort)  shall be
               limited to two hundred million dollars ($200,000,000).

          (c)  The  limitation set forth in Subsections  (b),  above,  shall not
               apply  with  respect  to:  (i)  third-party   claims  subject  to
               indemnification  pursuant  to the  Agreement;  (ii)  fees due and
               owing under this  Agreement  at the time of the claim;  and (iii)
               amounts subject of Cover as provided in Section 3.7(b).

          (d)  For the purposes of this  Section  10.2,  all amounts  payable or
               paid to third parties in connection with claims that are eligible
               for  indemnification  pursuant to this Agreement  shall be deemed
               direct damages.

                                       22
<PAGE>

     10.3. Insurance Requirements.

          (a)  During the Term,  WinStar  shall have and  maintain  in force the
               following insurance coverages:

               (i)  Worker's  Compensation  and Employer's  Liability.  Worker's
                    Compensation Insurance in amounts required by applicable law
                    and Employers  Liability Insurance with limits not less than
                    $1,000,000  each  accident.  If work is to be  performed  in
                    Nevada,  North  Dakota,  Ohio,  Washington,  Wyoming or West
                    Virginia,  the party shall  participate  in the  appropriate
                    state fund(s) to cover all eligible  employees and provide a
                    stop  gap  endorsement  for  these  monopolistic  states  in
                    WinStar's Worker's Compensation Insurance Program.

               (ii) Commercial General Liability.  WinStar shall carry broadform
                    general  liability  insurance  coverage for property damage,
                    bodily injury,  personal injury,  contractual  liability and
                    accidental  pollution  legal  liability  with coverage of at
                    least $10,000,000 per occurrence and in the aggregate. Total
                    limits   can   be   attained   by   the   inclusion   of  an
                    Umbrella/Excess Liability policy.

               (iii)Automobile   Liability.   WinStar  shall  carry   automobile
                    liability  insurance  written  on  the  occurrence  form  of
                    policy.  The policy  shall  provide  for  bodily  injury and
                    property  damage  liability  covering  the  operation of all
                    automobiles  used in connection  with  performing  under the
                    Agreement and shall provide  coverage of at least $2,000,000
                    per occurrence.

          (b)  WinStar  shall  cause  its  insurers  to  issue  certificates  of
               insurance  evidencing  that the  coverages  required  under  this
               Agreement are maintained in force. The minimum limits of coverage
               specified herein are not intended, and shall not be construed, to
               limit any liability or indemnity of WinStar under this Agreement.

          (c)  Nothing in this Agreement  shall be construed to prevent  WinStar
               from  satisfying  its  insurance  obligations  pursuant  to  this
               Agreement  under a blanket  policy or policies of insurance  that
               meet or exceed the requirements of this Article.

     10.4. Risk of Loss.

          (a)  Each  Party  shall  promptly  notify  the  other  of any  matters
               pertaining  to any  damage  or  impending  damage  to or  loss of
               Wireless Fiber  Connectivity known to it that could reasonably be
               expected to adversely affect the Wireless Fiber Connectivity.

          (b)  Each Party shall take all  reasonable  precautions  against,  and
               shall  assume  liability  for,  subject  to  the  terms  of  this
               Agreement,  any damage  caused by it to the property of the other
               Party.

          (c)  Neither  Party  shall  use,  or allow  others to use,  equipment,
               technologies,  or methods of operation  that interfere in any way
               with  or  adversely  affect  the  Williams  Connectivity  or  the
               permitted use thereof by Williams,  WinStar or  authorized  third
               parties.


                                       23
<PAGE>

          (d)  Williams  shall not cause or permit any part of the Williams T-1s
               to become subject to any  mechanic's  lien,  materialman's  lien,
               vendor's  lien or any  similar  lien or  encumbrance  whether  by
               operation of law or otherwise.

     10.5. Force Majeure.

          (a)  No  Party  shall  be  liable  for any  default  or  delay  in the
               performance of its obligations under this Agreement if and to the
               extent such default or delay is caused,  directly or  indirectly,
               by fire, flood, lightning, earthquake, elements of nature or acts
               of God, riots, civil disorders,  rebellions or revolutions in any
               country or any other cause beyond the reasonable  control of such
               Party;  provided,  however,  that (i) the non-performing Party is
               without  fault in causing  such  default or delay,  and (ii) such
               default  or delay  could not have been  prevented  by  reasonable
               precautions   and  cannot   reasonably  be  circumvented  by  the
               non-performing  Party  through  the  use  of  alternate  sources,
               workaround plans or other means,  including means contemplated by
               applicable disaster recovery processes or procedures).

          (b)  In such event the  non-performing  Party  shall be  excused  from
               further   performance  or  observance  of  the  obligation(s)  so
               affected for as long as such circumstances prevail and such Party
               continues to use  commercially  reasonable  efforts to recommence
               performance  or  observance   whenever  and  to  whatever  extent
               possible  without delay.  Any Party so delayed in its performance
               shall  immediately  notify the other  Party by  telephone  (to be
               confirmed  in  writing  within  two  (2)  business  days  of  the
               inception of such delay) and  describe at a  reasonable  level of
               detail the circumstances  causing such delay. The  non-performing
               party will provide the other party prompt  written  notice of the
               cessation or termination of the force majeure event.

11.  REMEDIES AND DISPUTE RESOLUTION

     Any  dispute  between  the  Parties  arising  out of or  relating  to  this
     Agreement, including with respect to the interpretation of any provision of
     this Agreement and with respect to the  performance by Williams or WinStar,
     shall be resolved as provided in this Article 11.

     11.1. Cumulative Nature.

          Except as otherwise  expressly  provided herein, all remedies provided
          for in this  Agreement  shall be cumulative and in addition to and not
          in lieu of any other  remedies  available  to either  Party at law, in
          equity or otherwise.

     11.2. Informal Dispute Resolution.

          (a)  Prior to the initiation of formal dispute  resolution  procedures
               (i.e.,  arbitration),  the Parties shall first attempt to resolve
               their  dispute  at the  senior  manager  level.  If that level of
               dispute  resolution is not successful,  the Parties shall proceed
               informally, as follows:

                                       24
<PAGE>

               (i)  Upon the written  request of either Party,  each Party shall
                    appoint a designated  representative  who does not otherwise
                    devote  substantially  full time to  performance  under this
                    Agreement,  whose task it will be to meet for the purpose of
                    endeavoring to resolve such dispute.

               (ii) The  designated  representatives  shall meet as often as the
                    Parties  reasonably  deem  necessary  in order to gather and
                    furnish  to the other all  information  with  respect to the
                    matter in issue that the Parties  believe to be  appropriate
                    and  germane  in  connection   with  its   resolution.   The
                    representatives  shall  discuss  the  problem and attempt to
                    resolve the  dispute  without  the  necessity  of any formal
                    proceeding.

               (iii)During the course of  discussion,  all  reasonable  requests
                    made   by  one   Party   to   another   for   non-privileged
                    non-confidential  information  reasonably  related  to  this
                    Agreement  shall be honored so that each of the  Parties may
                    be fully advised of the other's position.

               (iv) The specific format for the discussions shall be left to the
                    discretion of the designated representatives.

          (b)  Prior to instituting formal  proceedings,  the Parties will first
               have their chief executive  officers meet to discuss the dispute.
               This  requirement  shall  not  delay  the  institution  of formal
               proceedings  past any statute of  limitations  expiration  or for
               more than fifteen (15) days.

          (c)  Subject to Subsection (b), formal  proceedings for the resolution
               of a dispute may not be commenced until the earlier of:

               (i)  The designated representatives concluding in good faith that
                    amicable  resolution  through  continued  negotiation of the
                    matter does not appear likely; or

               (ii) Thirty  (30)  days  after the  initial  written  request  to
                    appoint a designated  representative  pursuant to Subsection
                    (a),   above,   (this   period   shall  be   deemed  to  run
                    notwithstanding any claim that the process described in this
                    Section 11.2 was not followed or completed).

          (d)  This  Section 11.2 shall not be construed to prevent a Party from
               instituting,  and a Party  is  authorized  to  institute,  formal
               proceedings  earlier to avoid the  expiration  of any  applicable
               limitations  period,  or to  preserve  a superior  position  with
               respect to other creditors or as provided in Section 11.6(a).

     11.3. Arbitration.

          If the  Parties  are unable to resolve a dispute  as  contemplated  by
          Section  11.2,  and that  dispute  is not  subject  to 11.6(a) of this
          Agreement,  then such dispute  shall be  submitted  to  mandatory  and
          binding  arbitration  at the election of either Party (the  "Disputing
          Party") pursuant to the following conditions:

          (a)  Selection of  Arbitrator.  The  Disputing  Party shall notify the
               American  Arbitration  Association  ("AAA") and the other  Party,
               describing in reasonable  detail the nature of the dispute,  (the

                                       25
<PAGE>

               "Dispute  Notice") and shall  request that the AAA furnish a list
               of five (5) possible arbitrators who have substantial  experience
               in the telecommunications industry. Each Party shall have fifteen
               (15) days to reject two (2) of the proposed arbitrators.  If only
               one individual has not been so rejected,  that person shall serve
               as arbitrator;  if two (2) or more  individuals  have not been so
               rejected,   the  AAA  shall  select  the  arbitrator  from  those
               individuals.

          (b)  Conduct of  Arbitration.  The arbitrator  shall allow  reasonable
               discovery in the forms  permitted  by the Federal  Rules of Civil
               Procedure,  to the  extent  consistent  with the  purpose  of the
               arbitration.  The arbitrator  shall have no power or authority to
               amend or  disregard  any  provision  of this  Section 11.3 or any
               other provision of this Agreement. In particular,  the arbitrator
               shall not have the  authority  to exclude the right of a Party to
               terminate this  Agreement when a Party would  otherwise have such
               right.  The arbitration  hearing shall be commenced  promptly and
               conducted expeditiously.

          (c)  Replacement  of Arbitrator.  Should the  arbitrator  refuse or be
               unable to proceed with  arbitration  proceedings as called for by
               this Section,  such arbitrator  shall be replaced and a rehearing
               shall  take  place  in  accordance  with the  provisions  of this
               Section.  In such case, the replacement for the arbitrator  shall
               be  either  selected  by the  AAA  from  the  original  group  of
               potential  arbitrators  that were not rejected by the Parties or,
               if there are no such arbitrators available, selected by repeating
               the process of selection described in Subsection (a), above.

          (d)  Findings and Conclusions.  The arbitrator rendering judgment upon
               disputes between Parties as provided in this Section shall, after
               reaching  judgment  and  award,  prepare  and  distribute  to the
               Parties a writing describing the findings of fact and conclusions
               of law  relevant  to such  judgment  and award.  The award of the
               arbitrator  shall  be  final  and  binding  on the  Parties,  and
               judgment   thereon  may  be  entered  in  a  court  of  competent
               jurisdiction.

          (e)  Place of Arbitration  Hearings.  Arbitration  hearings  hereunder
               shall  be held in  Chicago,  Illinois.  If the  Parties  mutually
               agree, arbitration hearings may be held in another location.

          (f)  Time of the Essence. The arbitrator is instructed that time is of
               the  essence  in  the  arbitration   proceeding,   and  that  the
               arbitrator  shall have the right and authority to issue  monetary
               sanctions  against  either of the  Parties  if, upon a showing of
               good cause,  that Party is unreasonably  delaying the proceeding.
               Recognizing  the express desire of the Parties for an expeditious
               means of dispute resolution,  the arbitrator shall limit or allow
               the Parties to expand the scope of discovery as may be reasonable
               under the circumstances.

     11.4. Termination.

          A Party shall not be in material  breach of this Agreement  unless and
          until the other Party  provides  it written  notice of default and the
          non-performing  party has failed to cure within thirty (30) days after
          receipt of such notice.  Any event of default may be waived in writing
          at the non-defaulting  Party's option.  Upon the failure of a Party to
          timely cure its material breach  hereunder  within the applicable cure

                                       26
<PAGE>


          period, the non-defaulting Party shall have the right to (i) terminate
          this Agreement or (ii) subject to the terms of this Article 11, pursue
          any legal  remedies it may have under  applicable law or principles of
          equity relating to such breach.

     11.5. Suspension of Service.

          If  Williams  does not make any  undisputed  payment  of at least  One
          Hundred Thousand Dollars  ($100,000) within thirty days of the payment
          due date,  WinStar may suspend  service to all Williams T-1s upon five
          (5) days' prior  written  notice if Williams does not cure within such
          period.  If such non-payment  continues for more than thirty (30) days
          after  receipt  of such  notice,  WinStar  shall  have  the  right  to
          terminate this Agreement.

     11.6. Litigation.

          (a)  Immediate  Injunctive  Relief.  The  only  circumstance  in which
               disputes  between  the  Parties  shall  not  be  subject  to  the
               provisions  of Sections  11.2 and 11.3 is where a Party,  in good
               faith,  determines  that a temporary  restraining  order or other
               injunctive relief is its only appropriate and adequate remedy. If
               a Party seeks immediate injunctive relief and does not prevail in
               substantial  part,  that Party shall pay the other  Party's costs
               and  attorneys'  fees to the extent  incurred in responding to or
               challenging the request for immediate injunctive relief.

          (b)  Jurisdiction.  The  Parties  consent to the  jurisdiction  of the
               courts of the State of New York and to jurisdiction  and venue in
               the United States District Court for the Southern District of New
               York for all  litigation  that may be brought with respect to the
               terms of, and the transactions and relationships contemplated by,
               this Agreement.  The Parties further consent to the  jurisdiction
               of any state court  located  within a district  that  encompasses
               assets of a Party  against which a judgment has been rendered for
               the  enforcement  of such judgment or award against the assets of
               such Party.

          (c)  Governing Law. This Agreement and  performance  under it shall be
               governed  by and  construed  in  accordance  with the laws of the
               State of New York without regard to its choice of law principles.

     11.7. Continued Performance.

          Each Party agrees to continue  performing its  obligations  under this
          Agreement while any dispute is being resolved except to the extent the
          issue in dispute precludes performance (dispute over payment shall not
          be deemed to preclude performance except as provided in Section 11.5).

12.  GENERAL

     12.1. Binding Nature and Assignment.

          (a)  This Agreement shall accrue to the benefit of and be binding upon
               the Parties hereto and any purchaser or any successor entity into
               which  either Party has been merged or  consolidated  or to which
               either Party has sold or transferred all or substantially  all of
               its assets.


                                       27
<PAGE>

          (b)  Neither  Party  may,  or shall  have the  power to,  assign  this
               Agreement or delegate such Party's obligations  hereunder without
               the prior written consent of the other, except to:

               (i)  An entity  that  acquires  all or  substantially  all of the
                    assets of such Party,

               (ii) Any Affiliate,

               (iii) A successor in a merger or acquisition of either Party, or

               (iv) In connection with any financing.

     12.2. Entire Agreement.

          This  Agreement,  including any attached  Schedules,  constitutes  the
          entire  agreement  between  the  Parties  with  respect to the subject
          matter in this Agreement, and supersedes all prior agreements, whether
          written or oral, with respect to the subject matter  contained in this
          Agreement.

     12.3. Tariff.

          WinStar  acknowledges  that  this  is  a  private  non-common  carrier
          agreement and that any  incorporation of WinStar tariff  provisions is
          done for the convenience of the Parties.

     12.4. Consents.

          As  between  the  parties,  Williams  shall  be  responsible  for  all
          arrangements with copyright  holders,  music licensing  organizations,
          performers'   representatives   or   other   parties   for   necessary
          authorizations,  clearances or consents  with respect to  transmission
          contents.

     12.5. Restriction of Transmissions.

          Williams  will not transmit  content that violates  applicable  law or
          carries  an  unreasonable  risk  of  leading  to  criminal,  civil  or
          administrative  proceedings  or  investigations  against  Williams  or
          WinStar.

     12.6. Use and Ownership.

          Neither Party shall have any right, title or interest to the equipment
          installed by the other Party.

     12.7. Non-Solicitation.

          Neither  Party  shall  directly  or  indirectly  solicit  the  other's
          employees or contractors  without the other Party's  written  consent,
          which shall not be unreasonably withheld.


                                       28
<PAGE>

     12.8. Notices.

          All  notices,   requests,   demands,  and  determinations  under  this
          Agreement (other than routine operational communications), shall be in
          writing  and shall be deemed  duly given (i) when  delivered  by hand,
          (ii) one (1) business  day after being given to an express,  overnight
          courier  with a system  for  tracking  delivery,  (iii)  when  sent by
          confirmed facsimile with a copy delivered  thereafter by another means
          specified in this  Section,  or (iv) four (4) business  days after the
          day of mailing,  when mailed by United States  registered or certified
          mail,  return receipt  requested,  postage  prepaid,  and addressed as
          follows:

          If to WinStar:                    If to Williams:
            WinStar Wireless, Inc.            Williams Communications, Inc.
            230 Park Avenue                   One Williams Center, Suite 26-5
            New York, NY  10169               Tulsa, Oklahoma  74172
            Attn:  EVP, General Counsel       Attn:  Contract Administration
            Facsimile:  212/922-1637          Facsimile:  918/573-6578

          With a copy to:                   With a copy to:
            WinStar Wireless, Inc.            Williams Communications, Inc.
            7799 Leesburg Pike                One Williams Center, Suite 4100
            Falls Church, Virginia 22043      Tulsa, Oklahoma  74172
            Attn:  VP, Commercial and         Attn:  General Counsel
              Legal Operations
            Facsimile:  703/288-6647          Facsimile:  918/573-3005


          A Party may from time to time  change  its  address  or  designee  for
          notification  purposes by giving the other prior written notice of the
          new  address  or  designee  and the date  upon  which  it will  become
          effective.

     12.9. Counterparts.

          This Agreement may be executed in several  counterparts,  all of which
          taken  together  shall  constitute  one single  agreement  between the
          Parties hereto.

     12.10. Relationship of Parties.

          Each  Party,  in  performing  hereunder,  is acting as an  independent
          contractor,  and such Party's personnel (including its subcontractors)
          shall not be considered or  represented  as employees or agents of the
          other  Party.  Neither  Party  is an  agent  of the  other  and has no
          authority  to  represent  that  Party  as to any  matters,  except  as
          expressly authorized in this Agreement.

     12.11. Severability.

          If any provision of this Agreement  conflicts with the law under which
          this  Agreement is to be  construed  or if any such  provision is held
          invalid  by an  arbitrator  or a  court  with  jurisdiction  over  the
          Parties,  such provision  shall be deemed to be restated to reflect as
          nearly  as  possible  the  original   intentions  of  the  Parties  in
          accordance  with applicable law. The remainder of this Agreement shall
          remain in full force and effect.


                                       29
<PAGE>

     12.12. Reasonableness, Consents and Approval.

               (a)  Where  this   Agreement   requires  a  Party  to  assist  or
                    cooperate,  such  requirement  shall not be  interpreted  to
                    require materially more than a commercially reasonable level
                    of effort (i.e.  the standard  applicable  will not be "best
                    efforts" or "exhausting all available means").

               (b)  Except  where  expressly  provided  as  being  in  the  sole
                    discretion   of  a   Party,   where   agreement,   approval,
                    acceptance,  consent,  or similar  action by either Party is
                    required  under this  Agreement,  such  action  shall not be
                    unreasonably  delayed or  withheld.  An  approval or consent
                    given by a Party under this Agreement  shall not relieve the
                    other  Party  from  responsibility  for  complying  with the
                    requirements of this Agreement, nor shall it be construed as
                    a waiver of any rights under this  Agreement,  except as and
                    to the extent otherwise  expressly provided in such approval
                    or consent.

     12.13. Waiver of Default.

          No waiver or  discharge  hereof  shall be valid  unless in writing and
          signed by an authorized representative of the Party against which such
          amendment,  waiver, or discharge is sought to be enforced.  A delay or
          omission by either  Party  hereto to exercise any right or power under
          this Agreement shall not be construed to be a waiver thereof. A waiver
          by  either  of the  Parties  hereto  of any  of  the  covenants  to be
          performed by the other or any breach thereof shall not be construed to
          be a waiver of any succeeding  breach thereof or of any other covenant
          herein contained.

     12.14. Survival.

          No  termination   of  this  Agreement   shall  affect  the  rights  or
          obligations of any Party with respect to any other  provisions of this
          Agreement that contemplate performance or observance subsequent to any
          termination or expiration of this Agreement.

     12.15. Public Disclosures.

          All media  releases,  public  announcements,  and  public  disclosures
          relating to this  Agreement or the subject  matter of this  Agreement,
          including  promotional  or  marketing  material,   but  not  including
          announcements intended solely for internal distribution or disclosures
          to the extent required to meet legal or regulatory requirements, shall
          be  coordinated  with and shall be subject to approval by both Parties
          prior to release.

     12.16. Third Party Beneficiaries.

          Except as otherwise  provided in this Agreement,  this Agreement shall
          not be  deemed  to  create  any  rights  in third  parties,  including
          suppliers and customers of a Party,  or to create any obligations of a
          Party to any such third parties.

     12.17. Amendment.

          (a)  This  Agreement  shall  not be  modified,  amended  or in any way
               altered  except  by an  instrument  in  writing  signed  by  both
               Parties.


                                       30
<PAGE>

          (b)  Unless otherwise expressly  permitted in this Agreement,  WinStar
               shall not make any changes to the Exhibits or Schedules  attached
               hereto that may have a material adverse impact on the performance
               or usability of Williams  Connectivity  without  Williams'  prior
               written consent.

     12.18. Order of Precedence.

          In the event of a conflict,  this Agreement shall take precedence over
          the Schedules attached hereto, and the Schedules shall take precedence
          over their attached Exhibits.

          This  order of  precedence  may be  modified  in a  subsequently-added
          Schedule or Exhibit if this  modification  is explicitly  noted in the
          corresponding amendment instrument.

     12.19. Interpretation.

          (a)  Terms other than those defined in this  Agreement  shall be given
               their  plain  English  meaning,  and those  terms,  acronyms  and
               phrases   known  in  the   telecommunications   and   information
               technology services industries shall be interpreted in accordance
               with their generally known meanings. Unless the context otherwise
               requires,  words  importing  the singular  include the plural and
               vice-versa.

          (b)  References to "Article,"  "Section,"  "Subsection" and "Schedule"
               mean references to an article, section, subsection or schedule of
               this Agreement,  as appropriate,  unless  otherwise  specifically
               stated.

          (c)  The article and section  headings in this  Agreement are intended
               to be  for  reference  purposes  only  and  shall  in no  way  be
               construed to modify or restrict any of the terms or provisions of
               this Agreement.

          (d)  The words "include," "includes" and "including," when following a
               general  statement  or term,  are not to be construed as limiting
               the general  statement or term to any specific item or matter set
               forth or to similar  items or matters,  but rather as  permitting
               the general statement or term to refer also to all other items or
               matters that could reasonably fall within its broadest scope.

     12.20. Covenant of Good Faith.

          Each Party  agrees that,  in its  respective  dealings  with the other
          Party under or in connection with this Agreement,  it will act in good
          faith.


IN WITNESS  WHEREOF,  this  Agreement  has been  executed  and  delivered by the
undersigned  officers,  thereunto duly authorized,  as of the date first written
above.

<TABLE>
<S>                                                            <C>  
WINSTAR WIRELESS, INC.                                          WILLIAMS COMMUNICATIONS, INC.




               /s/ Timothy R. Graham                                            /s/ Frank Semple
By:           --------------------------------------------      By:            ----------------------------------------
               Timothy R. Graham                                                Frank Semple
Name:         --------------------------------------------      Name:          ----------------------------------------
               Vice President                                                   President, Williams Network
Title         --------------------------------------------      Title:         ----------------------------------------
               December 17, 1998                                                December 17, 1998
Date:         --------------------------------------------      Date:          ----------------------------------------

</TABLE>




                       AGREEMENT TO PURCHASE LMDS LICENSE



         AGREEMENT  TO PURCHASE  LMDS  LICENSE,  dated as of July 10, 1998 (this
"Agreement") by and between WinStar Communications, Inc., a Delaware corporation
the "Purchaser"), CellularVision USA, Inc., a Delaware corporation ("CVUSA") and
CellularVision of New York, L.P., a Delaware limited partnership ("Seller"),

         WHEREAS, Seller holds the LMDS A Block License (the "License") from the
Federal  Communications   Commission  (the  "FCC")  for  the  New  York  Primary
Metropolitan  Statistical Area (i.e.,  the five boroughs  comprising the City of
New York, and the contiguous  New York State counties of  Westchester,  Rockland
and  Putnam),  free and  clear of all  liens,  claims,  rights of usage by third
parties and other encumbrances (collectively, "Liens"),

         WHEREAS, Seller and CVUSA have retained Wasserstein Perella & Co., Inc.
to advise them on the marketing and sale of the 850 MHz License and  Wasserstein
Perella & Co., Inc. has managed the sale process,  which  included,  among other
things,  contacting  a large number of  potential  purchasers  as well as active
negotiations  with certain  potential  purchasers,  all of which resulted in the
offer of the Purchase  Price and the Loans (as  hereinafter  defined) all on the
terms and  conditions  set forth herein,  which CVUSA deems to be the best offer
currently available for the 850 MHz License;

         WHEREAS, Seller intends to disaggregate 850 MHz of the spectrum covered
by the License,  comprised of the frequencies  between 27.5 and 28.35 GHz and to
be conveyed to Purchaser  pursuant to a license  granted by the FCC thereto (the
"850 MHz License") and  Purchaser  wishes to purchase the 850 MHz License,  upon
the terms and subject to the conditions set forth herein,  free and clear of all
Liens.

         WHEREAS,  holders of a  majority  of the  outstanding  shares of common
stock  of  CVUSA  wish  to  irrevocably   consent  to  this  Agreement  and  the
transactions contemplated hereby;

<PAGE>

         NOW,  THEREFORE,  in  consideration  of the  premises,  and the  mutual
conditions and obligations set forth herein,  the parties hereto hereby agree as
follows:

         1. Purchase Price; Loan. (a) The purchase price for the 850 MHz License
shall be $32,500,000,  of which a portion will be payable by offset of the total
outstanding principal amount and accrued interest on the Loan (as defined below)
and the  remainder  of which  will be payable by wire  transfer  of  immediately
available funds to Seller at the Closing (defined in Section 3).

         (b) As promptly as practicable  following the execution and delivery of
this Agreement by the parties hereto  (including the voting agreement of certain
holders  owning not less than 39% of the  outstanding  shares of common stock of
CVUSA),  Purchaser  will make an initial loan to Seller (the "Initial  Loan") in
the amount of  $3,500,000,  and,  when  Seller  shall have made the FCC  filings
contemplated  by Section  2(a) and CVUSA  shall have  obtained  the  stockholder
approval  contemplated by Section 13,  Purchaser will make an additional loan in
the amount of  $2,000,000  (such loan,  together  with the Initial  Loan and the
loans that  Purchaser may, in its sole  discretion,  make pursuant to Section 6,
the "Loans") at 7.5% per annum,  with interest and principal  payable in full at
the Closing by way of offset  against the  purchase  price then due, as provided
above, or on such earlier date as this Agreement may be terminated in accordance
with its terms, provided that in the event of such a termination,  such interest
rate  will be 18% per  annum.  The Loans  will be  secured  by a first  priority
perfected  security  interest  on all of the  assets  of  Seller  as to  which a
security interest may be granted,  including,  without limitation,  the proceeds
from such assets as well as from the sale or other transfer of FCC licenses,  it
being  understood  and agreed that (i) a vendor's  security  interest in certain
equipment has been assigned to NewStart Factors,  Inc. and (ii) the FCC licenses
may not be  subject  to  security  interests  as a  matter  of law.  Purchaser's
security  interest  will  extend to  after-acquired  property  and to  proceeds,
provided that Borrower will retain the right to enter into vendor  financing and
equivalent  secured financing  arrangements  with respect to equipment  acquired
after the date hereof.  CVUSA will  guarantee the repayment in full of the Loans
in accordance with its terms, and will secure its guarantee with a pledge of all
of the outstanding  shares of stock of  CellularVision  Capital Corp.,  the sole
general  partner  of  Seller,  and all of the  outstanding  limited  partnership

                                       2
<PAGE>

interests  in  Seller,  all of which are owned by CVUSA.  The  parties  agree to
prepare,  review  and  negotiate  in good  faith  and  execute  as  promptly  as
practicable  (and in any  event  prior to the  funding  of the  Loans)  mutually
acceptable  definitive  documentation  ((the "Loan Documents") in customary form
for  these  financing  transactions,   including,  without  limitation,  a  Loan
Agreement  (including  guaranty  provisions),   a  Note,  a  Security  Agreement
(including  pledge  provisions),  and UCC-1  forms.  To the  extent  there is an
inconsistency  between the Loan Documents and this Agreement with respect to the
Loans and related security arrangements, the Loan Documents shall control.

         2.  Government  Approvals;  Transition.  (a) As promptly as practicable
following  the execution  and delivery of this  Agreement,  Seller and Purchaser
will (i) file appropriate applications for the disaggregation of the License and
assignment  of the 850 MHz License to Purchaser and (ii) make such filings under
the  Hart-Scott-Rodino  Antitrust  Improvements  Act of 1976 and the  rules  and
regulations (collectively, the "HSR Act") as may be legally required in order to
consummate the transactions  contemplated herein, with the filing fee related to
any such filing to be shared by Purchaser and CVNY on a 50%/50% basis. Following
the making of such  applications  and  filings,  both  parties  will  diligently
attempt to obtain  successful  results  with  respect  thereto in a manner  that
permits the  consummation  of the  transactions  contemplated  herein as soon as
practicable.

                  (b)  Prior  to  the  Closing,   and  in  accordance  with  all
applicable legal and regulatory  requirements,  Seller will clear its operations
from  the  spectrum  covered  by the  850 MHz  License,  such  transition  to be
completed  in any event  within 90 days of the date of FCC  Approval  (as herein
defined).

         3. Closing.  The closing of the transactions  contemplated  herein (the
"Closing")  shall occur on the first business day (the "Closing Date") following
the first date upon which all of the following conditions are satisfied: (i) the
FCC shall have granted its consent to the  assignment  of the 850 MHz License to
Purchaser  and,  unless  waived by  Purchaser,  such consent shall have become a
final,  nonappealable order no longer subject to review or reconsideration ("FCC

                                       3
<PAGE>


Approval"); (ii) CVUSA shall have obtained the approval of its stockholders with
respect  to the  transactions  contemplated  hereby;  and (iii)  any  applicable
waiting  period  under the HSR Act shall have  expired  without  action taken to
prevent  the  consummation  of  the  transactions  contemplated  herein.  At the
closing,  Seller shall assign the 850 MHz License to Purchaser free and clear of
all Liens against payment of the Purchase Price as contemplated by Section 1.

         4.  Representations and Warranties.  (a) Each party (the "Representer")
hereby  represents  and warrants to the other that (i) the  Representer  has all
requisite  power and authority to execute this  Agreement and the Loan Documents
and perform its  obligations  hereunder and  thereunder,  (ii) all corporate and
partnership action necessary for the authorization, execution and performance by
the  Representer of its  obligations  hereunder and thereunder  have been taken,
except that,  in the case of CVUSA,  stockholder  approval may be required,  and
(iii) subject to obtaining the consent and approvals  referred to in paragraph 3
above,  the execution,  delivery and  performance of this Agreement and the Loan
Documents  does not and will not  require  the  consent  of any other  person or
entity, contravene the certificate of incorporation or by-laws or certificate of
limited partnership or partnership agreement of the Representer or conflict with
or result in a breach  or  violation  by the  Representer  of any law,  court or
administrative order or contract to which the Representer is a party or by which
the Representer is bound.

         (b) Seller and CVUSA  hereby  represent  and warrant that Seller is the
sole legal and beneficial  owner and holder of the License,  has the right under
applicable  law and FCC  regulations  to effect the  disaggregation  of spectrum
contemplated  hereby and that the License  is, and the 850 MHz License  will be,
held by Seller  free and clear of all Liens.  Without  limiting  the  foregoing,
Seller hereby represents and warrants that no person or entity other than Seller
has or will have the right to use all or any  portion of the  License or the 850
MHz License.  Seller hereby  further  represents  and warrants that (i) it is in
compliance  in all material  respects  with the  Communications  Act of 1934, as

                                       4
<PAGE>

amended,  and the rules,  regulations  and policies of the FCC,  (ii) Seller has
satisfied all build-out,  renewal,  construction  and other material  regulatory
requirements, and (iii) there are no pending complaints,  challenges, petitions,
appeals  or  other  regulatory  encumbrances  pending  or,  to the  best  of the
knowledge of Seller or CVUSA, threatened, against Seller or the License.

         (c) Each party will use all  commercially  reasonable  efforts to cause
all of its  representations  and warranties in this Agreement to remain true and
correct at all times  through the Closing  Date and to cause all  conditions  to
Closing to be satisfied.

         5. Closing  Conditions.  (a) Each Party's  obligation to close shall be
subject to the following  conditions (i) the other party's  representations  and
warranties  hereunder and under the Loan Documents  shall be true and correct on
and as of the Closing  Date as if made again on that date,  (ii) the other party
shall  have  performed  all  covenants  to have  been  performed  hereunder  and
thereunder  and (iii) the other party shall have  delivered a  certificate  of a
senior  officer as to the  matters in clauses (i) and (ii) above dated as of the
Closing Date.

         (b) Purchaser's  obligation to close shall be subject to the conditions
that (i) the  conditions  referred  to in  Sections  2(b) and 3 shall  have been
satisfied, (ii) there shall be no injunction or order of any court or government
agency restraining or invalidating any of the transactions  contemplated hereby,
and (iii) Purchaser shall have received opinions of Seller's counsel dated as of
the date  hereof and as of the  Closing  date in form and  substance  reasonably
satisfactory  to Purchaser and covering  such portion of the matters  covered by
Seller's and CVUSA's representations contained herein as are customarily covered
in legal opinions and subject to customary qualifications,  including an opinion
of FCC counsel substantially in the form attached.

         6.  Termination.  Either party which is not then in material  breach of
its  obligations  hereunder may terminate  this Agreement  without  liability by
written notice to the other party if the Closing Date shall not have occurred on
or before January 31, 1999,  provided,  however,  that upon  Purchaser's  notice

                                       5
<PAGE>


given at least 10 days prior to the date that  termination  would  otherwise  be
permitted,  such date shall be  extended to June 30,  1999 and,  thereafter,  to
December 31, 1999 if (i) Purchaser is not in material  breach of its obligations
hereunder and (ii) on each such occasion  Purchaser  makes an additional Loan of
$3.5 million in principal amount to the Seller on  substantially  the same terms
as the Loans.  Purchaser may terminate  this  Agreement at any time if CVUSA has
not obtained stockholder approval of this transaction by October 10, 1998.

         7. Transaction  Expenses.  Except as otherwise provided in Section 2(a)
and  Section 13, each of the  parties  hereto  will be  responsible  for its own
expenses  (including fees and expenses of legal counsel)  incurred in connection
with the transactions  contemplated hereby, provided that as of the Closing Date
(or earlier termination of this Agreement in accordance with its terms in a case
in which the expense reimbursement  provision of Section 13 do not apply) Seller
and CVUSA will  reimburse  Purchaser's  reasonable  fees and expenses of counsel
incurred in connection  with the  negotiation  and  preparation of the documents
relating to the transactions  contemplated hereby,  including the Loans, and the
prosecution  of the FCC  applications  contemplated  hereby,  provided  that the
amount  of  such  fees  and  expenses  related  to  the   documentation  of  the
transactions  through the funding of the Initial Loan and prosecution of the FCC
applications contemplated hereby shall not exceed $50,000. Each party represents
to the other that it has not incurred any  liability  for a broker's or finder's
fee in connection with the transactions  contemplated hereby, except that Seller
is liable to  Wasserstein  Perella & Co., Inc. for fees in connection  with such
transactions.

         8.  Publicity;  Disclosure.  Without  the prior  approval  of the other
party,  neither of the  parties  hereto  shall  disclose to the public or to any
third party any information  concerning the  transactions  contemplated  hereby,
other than  disclosures  to their  financial,  legal and other  advisors  and to
governmental  authorities  or the public as may, in the  opinion of counsel,  be
required by law.  Notwithstanding  the  foregoing,  CVUSA shall be  permitted to
include in the proxy statement  described in Section 13 hereof,  such details of
the transactions  contemplated  hereby as may be required by law;  provided that


                                       6
<PAGE>


Purchaser  shall have the right to review and comment thereon prior to the proxy
statement being filed with the SEC or distributed. The parties will cooperate in
the  preparation  of a joint press  release or  coordinated  but separate  press
releases  announcing  the  effectiveness  of this Agreement as soon as it occurs
pursuant to Section 12.

         9. Access. Until the Closing,  CVUSA and Seller will give Purchaser and
its  representatives  all access during ordinary  business hours to the premises
and  personnel of Seller and CVUSA and to all  accounting,  financial  and other
records applicable to Seller as Purchaser may reasonably request for the purpose
of  confirming  compliance  with this  Agreement and CVUSA and shall furnish all
information  with respect to the business and affairs of Seller as Purchaser may
reasonably  request  for  such  purpose.  CVUSA  and  Seller  will  cause  their
executives, employees, attorneys and accountants to make themselves available to
provide reasonable cooperation to Purchaser in connection therewith.

         10.  Exclusivity.  Neither  CVUSA nor Seller shall (nor shall either of
them permit their  representatives  or stockholders to) discuss a possible sale,
lease or other disposition of or by Seller or CVUSA (whether by sale of stock or
assets or otherwise)  that is not  consistent  with the sale to Purchaser of the
850 MHz License  contemplated  hereby or provide any  information  in connection
therewith to any other party or enter into any  agreements or  commitments to do
the same.

         11.  Assignment.  This Agreement is intended to be a binding  agreement
between  Purchaser,  CVUSA and Seller and shall bind and inure to the benefit of
the successors  and assigns of such parties;  provided that CVUSA and Seller may
not  assign  their  rights  or  delegate  their  obligations  hereunder  without
Purchaser's prior written consent,  which will not be unreasonably withheld. The
Purchaser may assign its rights hereunder to any of its wholly-owned or majority
controlled  subsidiaries,  provided that no such  assignment of its rights shall
relieve Purchaser of any of its obligations hereunder.

                                       7
<PAGE>


         12.  Effectiveness.  Simultaneously  with the execution and delivery of
this Agreement the following are expected to occur, upon the occurrence of which
this Agreement will come into full force and effect:

                  (a) Holders of not less than 39% of the issued and outstanding
shares of Common  Stock of CVUSA  shall  have  agreed  to vote  their  shares as
provided below;

                  (b) Seller shall have  executed and delivered to Purchaser the
Loan Documentation,  including arrangements with existing creditors as Purchaser
shall deem appropriate;

                  (c)  Purchaser  shall have  received such opinions of Seller's
counsel as it shall  reasonably  require in  connection  with FCC and  corporate
matters with  respect to the Loan  Documents,  the License and the  transactions
contemplated  hereby,  including,  if Purchaser so requires, a favorable opinion
from Purchaser's FCC counsel to the effect that there is no reason to expect (i)
that the transactions  contemplated hereby will materially  adversely affect the
regulatory  status  of  any of the  FCC  wireless  licenses  currently  held  by
Purchaser or any of its subsidiaries or (ii) that there is any reason to believe
that the disaggregation of spectrum is not permissible under applicable law.

         13.      Shareholder Approval; Break-up fee; Events of Bankruptcy.

                  (a) CVUSA has obtained the approval of a majority of its board
of  directors  to the  transactions  contemplated  hereby,  and  its  board  has
recommended and will continue to recommend,  so long as such  recommendation  is
consistent  with  their  fiduciary   duties  under   applicable  law,  that  its
stockholders vote to approve the transactions  contemplated  hereby.  CVUSA will
call a special  meeting of its  stockholders  as promptly as practicable for the
purpose of obtaining such approval, will file a preliminary proxy statement with
respect  thereto with the  Securities  and Exchange  Commission  within five (5)
business  days  of the  execution  of  this  Agreement  and  will  distribute  a
definitive  proxy  statement to  stockholders in accordance with applicable law,
and use its best  efforts to hold such  meeting  and  obtain  such  approval  as
quickly as possible.


                                       8
<PAGE>

                  (b) In the event a petition for relief under 11 U.S.C.  ss.101
et seq. (the "Bankruptcy Code") or similar State insolvency statute, is filed by
or against Seller or CVUSA,  each Seller and CVUSA agree to (i) consent to entry
of an order for relief under Chapter 11 of the Bankruptcy Code; (ii) continue to
comply with the terms of this Agreement;  and (iii) to the extent  necessary for
Seller or CVUSA to  continue to comply  with the terms of this  Agreement,  seek
Bankruptcy  Court  approval of the sale  contemplated  by this Agreement or take
such other  action as may be necessary or advisable to allow Seller and CVUSA to
continue to comply with the terms of this Agreement.

                  (c) in the event at any time on or prior to the  Closing  Date
(i) this Agreement is terminated by Seller or CVUSA (other than as a result of a
material breach by Purchaser) and a court  determines that specific  enforcement
in  accordance  with  the  provisions  of  Section  14(b)  is not  available  to
Purchaser, or (ii) Purchaser terminates this Agreement because CVUSA stockholder
approval has not been  obtained by October 10,  1998,  then  Purchaser  shall be
entitled to the following as liquidated damages, and not as a penalty:

                  (i)  Expense  Reimbursement:  Seller  and  CVUSA  jointly  and
severally shall reimburse Purchaser for its actual and reasonable  out-of-pocket
expenses,  not to exceed $325,000  (exclusive of the amounts payable pursuant to
Section 7)  incurred  in  furtherance  of this  Agreement  and the  transactions
contemplated herein, including without limitation,  attorneys' fees and expenses
incurred by  Purchaser  for  services  of outside  counsel in  negotiating  this
Agreement,  the Loan  Documents and all related  agreements,  performance of due
diligence, or otherwise (the "Expense Reimbursement"). Purchaser shall submit to
Seller  and  CVUSA an  itemized  statement  reflecting  such  actual  reasonable
expenses.  Within  five (5) days  thereafter,  Seller  and CVUSA  shall  make an
Expense  Reimbursement.  This  obligation  shall survive any termination of this
Agreement,  and shall be secured by the collateral under the security  agreement
being executed in relation to the Loans.


                                       9
<PAGE>

                  (ii)  Termination  Fee. Seller and CVUSA jointly and severally
shall, within five (5) days of such termination, pay $1,625,000 to the Purchaser
as a termination fee  ("Termination  Fee").  This  obligation  shall survive any
termination of this Agreement,  and shall be secured by the collateral under the
security agreement being executed in relation to the Loans.

         14. Specific  Performance;  Miscellaneous;  Conflict  Waiver.  (a) This
Agreement  shall be construed and enforced in accordance  with the internal laws
of the  State of New York.  This  Agreement  may be  executed  in any  number of
counterparts,  each of which  shall be an  original,  but which  together  shall
constitute one instrument.

                  (b)  Notwithstanding  the  provisions of Section  13(c)(i) and
(ii),  it is  understood  and agreed that money damages would not be an adequate
remedy for a breach of the Agreement by Seller or CVUSA and that Purchaser shall
be entitled to specific  performance and injunctive or other equitable relief as
a remedy for any such  breach.  Seller and CVUSA agree to waive any  requirement
for the securing or posting of any bond in  connection  with such  remedy.  Such
remedy shall not be deemed to be the exclusive  remedy for any such breach,  but
shall be in addition to all other  remedies  available to Purchaser at law or in
equity.

                  (c) Each of the parties hereto  acknowledges that Willkie Farr
& Gallagher regularly acts as counsel for each of them, and consents to the fact
that the New York  office  of such  firm will  provide  corporate  (but not FCC)
advice to CVUSA and Seller  (which will receive FCC advice from other  counsel),
its Washington  office will provide FCC (but not corporate) advice to Purchaser,
which is also represented by other counsel in this matter.

                            [Signature page follows]


<PAGE>




     IN WITNESS WHEREOF,  the undersigned have executed this Agreement as of the
date first above written.




                          WINSTAR COMMUNICATIONS, INC.



                            By:/s/ Timothy R. Graham
                            --------------------------
                                Timothy R. Graham
                            Title:


Accepted and agreed as of July 10, 1998


CELLULARVISION USA, INC.




By:_/s/ Shant Hovnanian
- - -------------------------
   Printed name: Shant Hownanian
   Title:

         CELLULARVISION OF NEW YORK, L.P.

         By: CELLULARVISION CAPITAL CORP.,
                  its General Partner

         By:___/s/ Shant Hovnanian
          --------------------------
                  Title:


                                       11

<PAGE>

         Voting Agreement by Stockholders

         In  consideration  of  the  Purchaser  executing  the  Agreement,   the
undersigned,  being the holders of not less than 39%  outstanding  shares of the
voting capital stock of CellularVision USA, Inc. which is entitled to vote a the
approval of the transactions  described herein, hereby expressly and irrevocably
agree  to vote  all  such  shares  in  favor  of  approval  of the  transactions
contemplated hereby at any special meeting of stockholders to be called for such
purpose and do hereby  agree to take such actions as  Purchaser  may  reasonably
request in order to further evidence such approval and consent.



                                                     /s/ Shant Hovnanian
                                                     ---------------------
                                                     Shant Hovnanian



                                                     /s/ Vahak Hovnanian
                                                     --------------------
                                                     Vahak Hovnanian


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