NEXTEL COMMUNICATIONS INC
8-K, 1997-09-05
RADIOTELEPHONE COMMUNICATIONS
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<PAGE>   1
               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): September 5, 1997
                                                  (September 4, 1997)


                       NEXTEL COMMUNICATIONS, INC.
        (Exact name of registrant as specified in its charter)


        Delaware                    0-19656               36-3939651
(State or other jurisdiction    (Commission File       (I.R.S. Employer
    of incorporation)               Number)           Identification No.)

  1505 Farm Credit Drive, Suite 100, McLean, Virginia       22102
       (Address of principal executive offices)           (Zip Code)



Registrant's telephone number, including area code:  (703) 394-3000



      (Former name or former address, if changed since last report)


<PAGE>   2

Item 5. Other Events.

     Nextel Communications, Inc. ("Nextel"), Nextel Finance Company, a wholly
owned subsidiary of Nextel ("NFC"), and certain subsidiaries of Nextel have
entered into definitive agreements which became effective on September 4, 1997
with respect to $500.0 million in additional financing, increasing Nextel's
total secured financing capacity under its financing agreements to $2.5
billion. These agreements provided for (i) amendments to the existing secured
credit facility with certain banks ( the "Bank Credit Facility") pursuant to
which $250.0 million in additional term loans were made, (ii) amendments to
the existing secured credit facility with Motorola, Inc., and NTFC Capital
Corporation and certain lenders (the "Vendor Credit Facility") pursuant to
which $50.0 million in additional term loans will be made available by
Motorola, and (iii) a new credit facility pursuant to which up to $200.0
million in additional term loans (the "Second Secured Borrowings") will be
made available by Motorola.

     Giving effect to these amendments, the Bank Credit Facility provides for
up to $1.905.0 billion of secured financing (consisting of a $1.085 billion
revolving loan and $820.0 million in term loans) and the Vendor Credit
Facility provides for up to $395.0 million of secured financing (consisting of
a $195.0 million revolving loan and $200.0 million of term loans), in each
case subject to the satisfaction or waiver of applicable borrowing conditions.
Borrowings under the Bank Credit Facility and Vendor Credit Facility, as
amended, are ratably secured by liens on assets of Nextel's subsidiaries that
are "restricted" subsidiaries under the terms of Nextel's public indentures.

     The agreement related to the Second Secured Borrowings provides for up to
$200.0 million of Second Secured Borrowings in the form of secured term loans
available prior to March 31, 1999.  The Second Secured Borrowings are secured
by the liens that secure borrowings under the Bank Credit Facility and Vendor
Credit Facility, but are second in ranking to such borrowings.  Availability
of the Second Secured Borrowings is subject to a number of conditions
including the prior borrowing of all amounts available under the Vendor Credit
Facility and the Bank Credit Facility.

     Copies of the amendments to the agreements relating to the Bank Credit
Facility and the Vendor Credit Facility and the agreement relating to the
Second Secured Borrowings, which are attached hereto as Exhibits 99.1, 99.2
and 99.3, respectively, are incorporated herein by reference, and the
descriptions herein are qualified in their entirety by such reference.

     On August 20, 1997 the Board of Directors approved the appointment of
Frank M. Drendel as a Director of Nextel.  The press release announcement is
attached hereto as Exhibit 99.4.


<PAGE>   3


Item 7. Financial Statements, Pro Forma Financial Information and Exhibits.

         (A)  Financial Statements of Business Acquired.
                    Not applicable.

         (B)  Pro Forma Financial Information.
                    Not applicable.

         (C)  Exhibits.

Exhibit No.  Exhibit Description


99.1         Amendment No. 3 to Credit Agreement, dated as of August 20,
             1997, amending the Credit Agreement dated as of September 27, 1996
             between Nextel Communications, Inc., Nextel Finance Company and
             the other Restricted Companies, the Lenders party thereto, Toronto
             Dominion (Texas), Inc., as Administrative Agent and The Chase
             Manhattan Bank, as Collateral Agent.

99.2         Amendment No. 3 to Vendor Financing Agreement, dated as of
             August 29, 1997, amending the Amended, Restated and Consolidated
             Credit Agreement, dated as of September 27, 1996 between Nextel
             Communications, Inc., Nextel Finance Company and the other
             Restricted Companies, Motorola, Inc. and NTFC Capital Corporation.

99.3         Second Secured Vendor Financing Agreement dated as of August
             29, 1997 among Nextel Communications, Inc., Nextel Finance Company
             and the other Restricted Companies and the Vendor Lenders party
             thereto.

99.4         Press Release dated August 25, 1997.


                               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.


                                NEXTEL COMMUNICATIONS, INC.



Date: September 5, 1997  By: /s/Thomas J. Sidman
                             Thomas J. Sidman
                             Vice President and General Counsel

<PAGE>   4


Exhibit No.  Exhibit Description

99.1         Amendment No. 3 to Credit Agreement, dated as of August 20,
             1997, amending the Credit Agreement dated as of September 27, 1996
             between Nextel Communications, Inc., Nextel Finance Company and
             the other Restricted Companies, the Lenders party thereto, Toronto
             Dominion (Texas), Inc., as Administrative Agent and The Chase
             Manhattan Bank, as Collateral Agent.

99.2         Amendment No. 3 to Vendor Financing Agreement, dated as of
             August 29, 1997, amending the Amended, Restated and Consolidated
             Credit Agreement, dated as of September 27, 1996 between Nextel
             Communications, Inc., Nextel Finance Company and the other
             Restricted Companies, Motorola, Inc. and NTFC Capital Corporation.

99.3         Second Secured Vendor Financing Agreement dated as of August
             29, 1997 among Nextel Communications, Inc., Nextel Finance Company
             and the other Restricted Companies and the Vendor Lenders party
             thereto.

99.4         Press Release dated August 25, 1997.



<PAGE>   1
                                                                [Execution Copy]


                      AMENDMENT NO. 3 TO CREDIT AGREEMENT


                 AMENDMENT NO. 3 TO CREDIT AGREEMENT dated as of August 20,
1997 between NEXTEL COMMUNICATIONS, INC. ("NCI"); NEXTEL FINANCE COMPANY (the
"Borrower") and the other Restricted Companies listed on the signature pages
hereto under the caption "RESTRICTED COMPANIES" (individually, a "Restricted
Company" and, collectively, the "Restricted Companies"); and the Lenders listed
on the signature pages hereto under the caption "LENDERS" (individually, a
"Lender" and, collectively, the "Lenders").

                 NCI, the Restricted Companies, the Lenders, Toronto Dominion
(Texas) Inc., as Administrative Agent, and The Chase Manhattan Bank, as
Collateral Agent, are parties to a Credit Agreement dated as of September 27,
1996 (as modified and supplemented and in effect from time to time, the "Credit
Agreement"), providing, subject to the terms and conditions thereof, for
extensions of credit (by means of loans and letters of credit) to be made by
the Lenders to the Borrower in an aggregate principal or face amount not
exceeding $1,655,000,000 (which, in the circumstances contemplated by Section
7.01(f) thereof, may be increased by $250,000,000 to $1,905,000,000).  NCI, the
Restricted Companies and the Lenders wish to consent to such increase of
$250,000,000 and to the amendment of the Credit Agreement in certain other
respects, and accordingly, the parties hereto hereby agree as follows:

                 Section 1.  Definitions.  Except as otherwise defined in this
Amendment No. 3, terms defined in the Credit Agreement are used herein as
defined therein.

                 Section 2.  Consent.  Subject to the satisfaction of the
conditions precedent specified in Section 6 below, but effective as of the date
hereof, the Lenders hereby consent to the making of Tranche E Loans under the
Credit Agreement upon the terms and conditions provided for in this Amendment
No. 3.  In addition, the Administrative Agent hereby consents to each Tranche E
Lender (as defined below), that is not already a "Lender" under the Credit
Agreement becoming a Lender under the Credit Agreement pursuant to this
Amendment No. 3.

                 Section 3.  Amendments.  Subject to the satisfaction of the
conditions precedent specified in Section 6 below, but effective as of the date
hereof, the Credit Agreement shall be amended as follows:

                 3.01  References Generally.  References in the Credit
Agreement (including references to the Credit Agreement as amended hereby) to
"this Agreement" (and indirect


                      Amendment No. 3 to Credit Agreement
<PAGE>   2
                                    - 2 -

references such as "hereunder", "hereby", "herein" and "hereof") shall be
deemed to be references to the Credit Agreement as amended hereby.

                 3.02  Definitions.  Appropriate references to matters relating
to the Tranche E Loans are inserted into Section 1.01 of the Credit Agreement
by adding the following new definitions (to the extent not already included in
said Section 1.01) and inserting the same in the appropriate alphabetical
locations and amending the following definitions (to the extent already
included in said Section 1.01), as follows:

                        (i)  Amendment No. 3:  a definition of "Amendment No.
         3" is hereby inserted as follows:

                          "Amendment No. 3" means Amendment No. 3 to this
                 Agreement.

                       (ii)  Amendment No. 3 Effective Date:  a definition
         of "Amendment No. 3 Effective Date" is hereby inserted as follows:

                          "Amendment No. 3 Effective Date" means the date on
                 which the conditions to the effectiveness of the amendments
                 provided for in Amendment No. 3 set forth in Section 6 thereof
                 are satisfied (or waived in accordance with said Section 6).

                      (iii)  Applicable Rate:  clause (a) of the definition
         of "Applicable Rate" is hereby amended to read in its entirety as
         follows:

                          "(a)  in the case of Tranche D Term Loans or
                 Tranche E Loans, for any day, 2% with respect to any Base Rate
                 Loan and 3% with respect to any Eurodollar Loan and".

                       (iv)  Arrangers:  a definition of "Arrangers" is hereby
         inserted as follows:

                          "Arrangers" means The Toronto-Dominion Bank, The
                 Chase Manhattan Bank, J.P. Morgan Securities Inc., Barclays
                 Bank PLC and NationsBank of Texas, N.A.

                        (v)  Class:  in the definition of "Class", a comma is
         inserted in lieu of the word "or" after the reference to "Tranche C
         Term Loans" and the words "or Tranche E Loans" are inserted after the
         reference to "Tranche D Term Loans".

                       (vi)  Commitments:  in the definition of "Commitments", 
         a comma is inserted in lieu of the word "and" after the reference to 
         "Tranche C Term Loan





                      Amendment No. 3 to Credit Agreement
<PAGE>   3
                                     - 3 -


         Commitments" and the words "and Tranche E Commitments" are inserted
         after the reference to "Tranche D Term Loan Commitments".

                        (vii)  Interest Period:  clause (y) of the definition
         of "Interest Period" is hereby amended to read in its entirety as
         follows:

                            "(y)  no Interest Period for any Tranche D Term
                 Loan Borrowing or Tranche E Loan Borrowing may commence before
                 and end after any Principal Payment Date unless, after giving
                 effect thereto, the aggregate principal amount of the Tranche
                 D Term Loans or Tranche E Loans, as the case may be, having
                 Interest Periods that end after such Principal Payment Date
                 shall be equal to or less than the aggregate principal amount
                 of the Tranche D Term Loans or Tranche E Loans, respectively,
                 scheduled to be outstanding after giving effect to the
                 payments of principal required to be made on such Principal
                 Payment Date and"

                       (viii)  Required Tranche E Lenders:  a definition of
         "Required Tranche E Lenders" is hereby inserted as follows:

                            "Required Tranche E Lenders" means, at any time,
                 Lenders having Tranche E Loans representing at least 51% of
                 the total Tranche E Loans at such time.

                         (ix)  Second Secured Intercreditor and Collateral
         Agency Agreement:  a definition of "Second Secured Intercreditor and
         Collateral Agency Agreement" is hereby inserted as follows:

                            "Second Secured Intercreditor and Collateral
                 Agency Agreement" means a Second Secured Intercreditor and
                 Collateral Agency Agreement substantially in the form of
                 Exhibit B to Amendment No. 3 hereto (or such other form as may
                 be approved by the Required Lenders, NCI and the Collateral
                 Agent) among NCI, the Restricted Companies, the "Vendor
                 Lenders" party thereto and the Collateral Agent.

                          (x)  Second Secured Vendor Financing Agreement:  a
         definition of "Second Secured Vendor Financing Agreement" is hereby
         inserted as follows:

                            "Second Secured Vendor Financing Agreement" means a
                 Second Secured Vendor Financing Agreement, substantially in
                 the form of the draft thereof dated August 22, 1997,
                 previously delivered to each of the Lenders (or such other
                 form as may be approved by the Required Lenders), among NCI,
                 the Restricted Companies and Motorola.





                      Amendment No. 3 to Credit Agreement
<PAGE>   4
                                     - 4 -



                          (xi)  Tranche E Commitment:  a definition of "Tranche
         E Commitment" is hereby inserted as follows:

                             "Tranche E Commitment" means, with respect to each
                 Lender, the commitment of such Lender to make a Tranche E Loan
                 hereunder.  The amount of each Lender's Tranche E Commitment
                 is set forth on Schedule 2.01, provided that if such Lender
                 fails to execute and deliver this Amendment No. 3 on or prior
                 to the Amendment No. 3 Effective Date, the amount of such
                 Lender's Tranche E Commitment set forth opposite said Lender's
                 name shall be reallocated ratably amongst the Arrangers.  The
                 aggregate original amount of the Tranche E Commitments is
                 $250,000,000.

                         (xii)  Tranche E Lender:  a definition of "Tranche E
         Lender" is hereby inserted as follows:

                             "Tranche E Lender" means (a) a Lender that has a
                 Tranche E Commitment set forth opposite its name on Schedule
                 2.01 and (b) thereafter, the Lenders from time to time holding
                 Tranche E Loans after giving effect to any assignments thereof
                 permitted by Section 10.04.

                        (xiii)  Tranche E Loan:  the definition of "Tranche E
         Loan" is hereby amended to read in its entirety as follows:

                             "Tranche E Loan" means a Loan made pursuant to
                 Section 2.01(d).

                 3.03  Tranche E Commitments.  Section 2.01 of the Credit
Agreement is hereby amended by inserting a new paragraph (d) at the end thereof
to read as follows:

                 "(d)  Tranche E Loans.  Subject to the terms and conditions
         set forth herein, each Tranche E Lender agrees to make a single
         Tranche E Loan to the Borrower on the Amendment No. 3 Effective Date
         in a principal amount equal to such Lender's Tranche E Commitment.
         Proceeds of Tranche E Loans shall be available for any use permitted
         under Section 6.09."

                 3.04  Requests for Borrowings.  Clause (i) of Section 2.03 of
the Credit Agreement is hereby amended to read in its entirety as follows:

                 "(i)  whether the requested Borrowing is to be a Tranche A
         Revolving Credit Borrowing, Tranche B Revolving Credit Borrowing,
         Tranche C Term Loan Borrowing, Tranche D Term Loan Borrowing or
         Tranche E Loan Borrowing;"





                      Amendment No. 3 to Credit Agreement
<PAGE>   5
                                     - 5 -


                 3.05  Termination of Commitments.  Section 2.07(a) of the
Credit Agreement is hereby amended to read in its entirety as follows:

                 "(a)  Unless previously terminated, (i) the Tranche A
         Revolving Credit Commitments and the Tranche B Revolving Credit
         Commitments shall terminate at the close of business on the Revolving
         Credit Maturity Date, (ii) the Tranche C Term Loan Commitments shall
         terminate at the close of business on the last day of the Tranche C
         Term Loan Availability Period, (iii) the Tranche D Term Loan
         Commitments shall terminate after the Borrowing of Tranche D Term
         Loans on the Effective Date and (iv) the Tranche E Commitments shall
         terminate after the Borrowing of Tranche E Loans on the Amendment No.
         3 Effective Date."

                 3.06  Repayment of Loans.  Section 2.08(c) of the Credit
Agreement is hereby amended by adding a new paragraph at the end thereof to
read as follows:

                 "The Borrower hereby unconditionally promises to pay to the
         Administrative Agent for the account of the Tranche E Lenders the
         principal of the Tranche E Loans in eleven installments payable on the
         Principal Payment Dates as follows:

                   Principal Payment Date                
                 Falling on or Nearest to:                Amount of Installment
                 -------------------------                ---------------------

                    March 31, 2001                             $   625,000
                    June 30, 2001                              $   625,000
                    September 30, 2001                         $   625,000
                    December 31, 2001                          $   625,000
                                                              
                    March 31, 2002                             $   625,000
                    June 30, 2002                              $   625,000
                    September 30, 2002                         $   625,000
                    December 31, 2002                          $   625,000
                                                              
                    March 31, 2003                             $   625,000
                    June 30, 2003                             $244,375,000"

                 3.07  Prepayments.  Paragraph (a), and the first paragraph of
(b)(ii), of Section 2.09 of the Credit Agreement are hereby amended in their
entireties to read as follows:

                 "(a)  Optional Prepayments.  The Borrower shall have the right
         at any time and from time to time to prepay any Borrowing in whole or
         in part, subject to prior notice in accordance with paragraph (d) of
         this Section 2.09.  Prepayments of Tranche





                      Amendment No. 3 to Credit Agreement
<PAGE>   6
                                     - 6 -


         C Term Loan Borrowings, Tranche D Term Loan Borrowings and Tranche E
         Loan Borrowings under this Section 2.09(a) shall be applied to each of
         such Classes of Borrowings (i) as between such Classes of Borrowings,
         pro rata in accordance with the respective aggregate principal amounts
         of the Loans of such Classes outstanding on the date of prepayment and
         (ii) as within such Classes of Loans, to the respective installments
         thereof in the direct order of their maturities.

                          (ii)  Sale of Assets.  Without limiting the
         obligation of the Restricted Companies to obtain the consent of the
         Required Lenders to any Disposition not otherwise permitted hereunder,
         the Borrower agrees, on or prior to the occurrence of any Disposition
         (herein, the "Current Disposition") as to which the estimated amount
         of the Net Cash Payments, together with all prior Dispositions as to
         which a prepayment has not yet been made under this Section
         2.09(b)(ii) and as to which a report contemplated by this Section
         2.09(b)(ii) has not been delivered, shall exceed $5,000,000, to
         deliver to the Administrative Agent a report certified by a Financial
         Officer, in form and detail reasonably satisfactory to the
         Administrative Agent, with respect to such Current Disposition and all
         such prior Dispositions setting out the estimated amount of the Net
         Cash Payments of all such Dispositions that will (on the date of the
         Current Disposition) have been received in cash, whereupon the
         Borrower will prepay the Loans hereunder and under the Vendor
         Facilities (and provide cover for LC Exposure as specified in clause
         (iv) of this Section 2.09), and the Commitments hereunder and under
         the Vendor Facilities shall be subject to automatic reduction, as
         follows:"

                 3.08  Alternate Rate of Interest.  Clause (b) of Section 2.12
of the Credit Agreement is hereby amended to read in its entirety as follows:

                 "(b)  if such Borrowing is of a particular Class of Loans, the
         Administrative Agent is advised by the Required Revolving Credit
         Lenders, the Required Tranche C Term Loan Lenders, the Required
         Tranche D Term Loan Lenders or the Required Tranche E Lenders, as the
         case may be, that the Adjusted LIBO Rate or the LIBO Rate, as
         applicable, for such Interest Period will not adequately and fairly
         reflect the cost to such Lenders of making or maintaining their Loans
         of such Class included in such Borrowing for such Interest Period;"

                 3.09  Public Note Indentures.  Section 4.17 of the Credit
Agreement is hereby amended to read in its entirety as follows:

                 "SECTION 4.17.  Public Note Indentures.  NCI has heretofore
         delivered to the Administrative Agent a true and complete copy of each
         Public Note Indenture (including all modifications and supplements
         thereto).  The Restricted Companies constitute all of





                      Amendment No. 3 to Credit Agreement
<PAGE>   7
                                     - 7 -


         the "Restricted Subsidiaries" on the date hereof under and as defined
         in the Public Note Indentures."

                 3.10  Conditions to Each Extension of Credit.  Section 5.02 of
the Credit Agreement is hereby amended to read in its entirety as follows:

                 "SECTION 5.02.  Each Extension of Credit.  The obligation of
         each Lender to make a Loan on the occasion of any Borrowing, and of
         any Issuing Bank to issue, amend, renew or extend any Letter of
         Credit, is subject to the satisfaction of the following conditions:

                          (a)  Representations and Warranties.  The
                 representations and warranties of each Credit Party set forth
                 in this Agreement and the other Loan Documents shall be true
                 and correct on and as of the date of such Borrowing, or (as
                 applicable) the date of issuance, amendment, renewal or
                 extension of such Letter of Credit, both before and after
                 giving effect thereto and to the use of the proceeds thereof
                 (or, if any such representation or warranty is expressly
                 stated to have been made as of a specific date, such
                 representation or warranty shall be true and correct as of
                 such specific date).

                          (b)  No Defaults.  At the time of and immediately
                 after giving effect to such Borrowing, or (as applicable) the
                 date of issuance, amendment, renewal or extension of such
                 Letter of Credit, no Default shall have occurred and be
                 continuing.

                          (c)  Secured Indebtedness to Revenue Ratio.  After
                 giving effect to such Borrowing, or such issuance, amendment,
                 renewal or extension of such Letter of Credit, the Secured
                 Indebtedness to Revenue Ratio shall not exceed the applicable
                 amount set forth in Section 7.08(f).

         Each Borrowing Request, or request for issuance, amendment, renewal or
         extension of a Letter of Credit, shall be deemed to constitute a
         representation and warranty by the Borrower (both as of the date of
         such Borrowing Request, or request for issuance, amendment, renewal or
         extension, and as of the date of the related Borrowing or issuance,
         amendment, renewal or extension) as to the matters specified in
         paragraphs (a), (b) and (c) of this Section 5.02."

                 3.11  Prepayments.  Section 6.01(d) of the Credit Agreement is
hereby amended in its entirety to read as follows:

                 "(d)  concurrently with any delivery of financial statements
         under clause (a), (b) or (c) above, a certificate of a Financial
         Officer of each of NCI and the Borrower





                      Amendment No. 3 to Credit Agreement
<PAGE>   8
                                     - 8 -


         (i) certifying as to whether a Default has occurred and, if a Default
         has occurred, specifying the details thereof and any action taken or
         proposed to be taken with respect thereto, (ii) setting forth
         reasonably detailed calculations demonstrating compliance with
         Sections 7.01(d), 7.01(g), 7.03(f), clauses (iv) through (viii) of
         7.04(a), 7.05(c) and 7.08 (which calculations shall include the
         corresponding figures for the most-recently ended fiscal quarter with
         respect to Capital Expenditures and Debt Service necessary to
         demonstrate compliance with said Section 7.08), (iii) setting forth
         the estimated amount of Net Cash Payments received during the
         most-recently ended fiscal quarter from Dispositions during such
         quarter and (iv) stating whether any change in GAAP or in the
         application thereof has occurred since the later of the date of the
         financial statements as at December 31, 1995 referred to in Section
         4.04 and the date of the last certificate delivered pursuant to this
         clause (d) and, if any such change has occurred, specifying the effect
         of such change on the financial statements accompanying such
         certificate;"

                 3.12  Planned Option Issuances.  Section 6.12 of the Credit
Agreement is hereby amended to read in its entirety as follows:

                 "SECTION 6.12.  Planned Option Issuances.  NCI will,
         immediately upon receipt thereof, contribute to one or more of the
         Restricted Companies, as additional equity capital in respect of the
         common stock of the Restricted Companies, any proceeds received by NCI
         after the date hereof from Planned Option Issuances.  In addition, NCI
         will from time to time make such contributions of capital to the
         Restricted Companies as shall be necessary so that the aggregate
         amount of Contributed Capital (i) as at July 31, 1997 shall be at
         least equal to $232,000,000, (ii) as at July 31, 1998 shall be at
         least equal to $550,000,000 and (iii) as at December 31, 1999 shall at
         least equal to $1,100,000,000."

                 3.13  Indebtedness.  Paragraphs (f), (g) and (h) of Section
7.01 of the Credit Agreement are hereby amended to read in their entirety, and
a new paragraph (i) is inserted in said Section 7.01, as follows:

                 "(f)  Indebtedness of the Borrower (and Guarantees thereof by
         the other Restricted Companies pursuant to the Restricted Company
         Guarantee and Security Agreement, and by NCI pursuant to Article III)
         in an aggregate principal amount not exceeding $250,000,000 in respect
         of Tranche E Loans hereunder;

                 (g)  other Indebtedness (in addition to any amounts permitted
         pursuant to the foregoing paragraphs (a) through (f) and the following
         paragraphs (h) and (i) of this Section 7.01) of the Restricted
         Companies in an aggregate principal amount not exceeding $75,000,000
         at any time outstanding (or such greater amount to which the Required
         Lenders shall have consented);





                      Amendment No. 3 to Credit Agreement
<PAGE>   9
                                     - 9 -



                 (h)  other unsecured Indebtedness of NCI in an aggregate
         principal amount not exceeding $10,000,000 at any time outstanding (or
         such greater amount to which the Required Lenders shall have
         consented); and

                 (i)  Indebtedness of the Credit Parties under the Second
         Secured Vendor Financing Agreement in an aggregate principal amount
         not exceeding the sum of  $200,000,000, plus any amount of additional
         principal resulting from the addition of accrued interest to the
         aggregate principal amount of such Indebtedness pursuant to Section
         2.11(c)(ii) of the Second Secured Vendor Financing Agreement."

                 3.14  Certain Permitted Liens.  Clause (a) the second
paragraph of Section 7.02 of the Credit is hereby amended to read in its
entirety as follows:

                 "(a)  Liens created by the Security Documents securing the
         obligations of the Restricted Companies hereunder (including in
         respect of Tranche E Loans), under the Vendor Financing Agreement and
         under the Security Documents (in each case subject to the provisions
         of the Intercreditor and Collateral Agency Agreement), and under the
         Second Secured Vendor Financing Agreement (subject to the provisions
         of the Second Secured Intercreditor and Collateral Agency Agreement);"

                 3.15  Certain Intercompany Transactions.  Clauses (b) and (d)
of the second paragraph of Section 7.03 of the Credit Agreement are hereby
amended to read in their entirety as follows:

                 "(b)  any Restricted Company may merge into any other
         Restricted Company, provided that no such merger may involve a License
         Company, unless (x) immediately after giving effect thereto no Default
         shall have occurred and be continuing and (y) in the case of any
         License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations, the surviving entity in such merger is
         a License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations;

                 (d)  any Restricted Company other than the Borrower may sell,
         transfer, lease or otherwise dispose of its assets to another
         Restricted Company, provided that no such transaction may involve a
         disposition of assets of any License Company unless (x) immediately
         after giving effect thereto no Default shall have occurred and be
         continuing and (y) in the case of any transfer of assets by a License
         Company substantially all of whose assets consist of FCC Licenses or
         PUC Authorizations, the acquiror of such assets (after giving effect
         to such acquisition) is a License Company substantially all of whose
         assets consist of FCC Licenses or PUC Authorizations;"





                      Amendment No. 3 to Credit Agreement
<PAGE>   10
                                     - 10 -


                 3.16  Acquisition Baskets.  Clauses (vii) and (viii) of
Section 7.04(a) of the Credit Agreement are hereby amended to read in their
entirety as follows:

                     "(vii)  this clause (vii) has been intentionally left
         blank;

                     (viii)  acquisitions of FCC Licenses in the 800 MHz
         or 900 MHz band (other than pursuant to the auction referred to in
         clause (vi) above), and acquisitions of any Mobile Communications
         Business and the related assets of any other Person (or, if for the
         purpose of enabling the Restricted Companies to create contiguous
         blocks of spectrum covered by the SMR Licenses of the Restricted
         Companies, acquisitions of cellular telephone and other businesses),
         whether by way of purchase of assets or stock, by merger or
         consolidation or otherwise, so long as:

                          (A)  the aggregate Purchase Price for all such
                 acquisitions consummated after the Amendment No. 3 Effective
                 Date (excluding any portion thereof that shall have been paid
                 through the issuance of equity securities of NCI, and
                 excluding acquisitions pursuant to the terms of one or more
                 definitive agreements as in effect on the Amendment No.  3
                 Effective Date) shall not exceed $275,000,000;

                          (B)  each such acquisition of FCC Licenses is for the
                 purpose of enabling the Restricted Companies to create
                 contiguous blocks of spectrum covered by the SMR Licenses of
                 the Restricted Companies;

                          (C)  any such acquisition of a Mobile Communications
                 Business (if by purchase of assets, merger or consolidation)
                 shall be effected in such manner so that the acquired
                 business, and the related assets, are owned by a Restricted
                 Company (which may include a new Wholly Owned Subsidiary that
                 becomes a Restricted Company pursuant to Section 6.11(a)) and,
                 if effected by merger or consolidation involving the Borrower,
                 the Borrower shall be the continuing or surviving entity;

                          (D)  any such acquisition of a Mobile Communications
                 Business (if by purchase of stock) shall be effected in such
                 manner so that the acquired entity becomes a Wholly Owned
                 Subsidiary that becomes a Restricted Company pursuant to
                 Section 6.11;

                          (E)  if the fair market value of the assets of any
                 Mobile Communications Business to be so acquired shall exceed
                 $10,000,000, the Restricted Companies shall deliver to the
                 Administrative Agent (which shall promptly forward copies
                 thereof to each Lender, upon request by such Lender) (x) no
                 later than five Business Days prior to the consummation of
                 each such





                      Amendment No. 3 to Credit Agreement
<PAGE>   11
                                     - 11 -


                 acquisition (or such earlier date as shall be five Business
                 Days after the execution and delivery thereof), executed
                 counterparts of the respective agreements or instruments
                 pursuant to which such acquisition is to be consummated
                 (including any related management, non-compete, employment,
                 option or other material agreements), any schedules to such
                 agreements or instruments and all other material ancillary
                 documents to be executed or delivered in connection therewith
                 and (y) promptly following request therefor, copies of such
                 other information or documents relating to each such
                 acquisition as the Administrative Agent or the Required
                 Lenders shall have reasonably requested;

                          (F)  following consummation of each such acquisition,
                 (x) the Restricted Companies shall have complied with the
                 requirements of Section 7.09(b) with respect to any FCC
                 Licenses or PUC Authorizations acquired in such acquisition
                 and (y) all Authorizations required by the FCC in connection
                 with such acquisition shall have been duly granted pursuant to
                 a Final Order and (if the fair market value of the assets so
                 acquired shall exceed $10,000,000 and the Administrative Agent
                 or any Lender shall have requested the same) the
                 Administrative Agent and the Lenders shall have received an
                 opinion of counsel with respect to such acquisition that is
                 satisfactory in form and substance to the Required Lenders;

                          (G)  to the extent applicable, the Restricted
                 Companies shall have complied with the provisions of Section
                 6.11, including delivery to the Collateral Agent of (x) the
                 certificates evidencing any capital stock of a Restricted
                 Company, accompanied by undated stock powers executed in blank
                 and (y) the agreements, instruments, opinions of counsel and
                 other documents required under said Section 6.11 to be
                 delivered;

                          (H)  in the case of a transaction described in clause
                 (E) above, and upon request by the Administrative Agent, the
                 Borrower shall deliver to the Administrative Agent a
                 supplement to Schedule 4.13 setting forth a list of the
                 respective SMR Licenses, other FCC Licenses and PUC
                 Authorizations acquired in connection with such acquisition;
                 and

                          (I)  both immediately prior to each such acquisition
                 and after giving effect thereto, no Default shall have
                 occurred and be continuing; and"





                      Amendment No. 3 to Credit Agreement
<PAGE>   12
                                     - 12 -


                 3.17  Restrictive Agreements.  Clause (y) of Section
7.07(b)(i) of the Credit Agreement is hereby amended to read in its entirety as
follows:

                          "(y)  consisting of customary restrictions on
                 transfers of site leases (provided that, except for leases
                 within the scope of the exceptions contained in Section 6.13
                 of the Restricted Company Guaranty and Security Agreement, the
                 Restricted Companies agree that any such lease entered into
                 after September 27, 1996 shall expressly permit the creation
                 of a security interest in the rights of the respective
                 Restricted Company party thereto as security for indebtedness
                 for borrowed money, or guaranties thereof), or"

                 3.18  Business Activities.  Section 7.09(a) of the Credit
Agreement is hereby amended to read in its entirety as follows:

                 "(a)  Business Activities.  No Restricted Company will engage
         to any substantial extent in any line or lines of business activity
         other than the Mobile Communications Business, and businesses
         reasonably related thereto, provided that nothing herein shall be
         deemed to prohibit the Restricted Companies from acquisitions pursuant
         to Section 7.04(a)(viii) of FCC Licenses in the 800 MHz or 900 MHz
         bands, or of cellular telephone and other businesses, for the purpose
         of enabling the Restricted Companies to create contiguous blocks of
         spectrum covered by the SMR Licenses of the Restricted Companies."

                 3.19  Modifications to Certain Agreements.  The first
paragraph of Section 7.10 of the Credit Agreement is hereby amended to read in
its entirety as follows:

                 "SECTION 7.10.  Modifications to Certain Agreements;
         Prepayments of Vendor Facilities.  The Credit Parties will not consent
         to any modification, supplement or waiver of any of the provisions of
         the Overhead Services Agreement (other than to add new Restricted
         Companies as parties thereto), the Tax Sharing Agreement (other than
         to add new subsidiaries of NCI as parties thereto) or the Vendor
         Financing Agreement (other than amendments thereto to conform the
         terms of the Vendor Financing Agreement to the terms of this Agreement
         following any amendment hereto or to increase the amount of the Vendor
         Facilities thereunder to the extent permitted under Section 7.01(b)),
         nor will they terminate or reduce any of the commitments to provide
         financing under the Vendor Financing Agreement, without, in each case,
         the prior consent of the Administrative Agent (with the approval of
         the Required Lenders).  In addition, NCI will not consent to any
         modification, supplement or waiver of any of the provisions of the
         Second Secured Vendor Financing Agreement (other than amendments
         thereto to conform the terms of the





                      Amendment No. 3 to Credit Agreement
<PAGE>   13
                                     - 13 -


         Second Secured Vendor Financing Agreement to the terms of this
         Agreement following any amendment hereto), the Public Note Indentures
         or the Public Notes without the prior consent of the Administrative
         Agent (with the approval of the Required Lenders)."

                 3.20  Agency Provisions.  The third sentence of the third
paragraph of Article IX of the Credit Agreement is hereby amended to read in
its entirety as follows:

                 "Neither Agent shall be liable for any action taken or not
         taken by it with the consent or at the request of the Required Lenders
         or, if provided herein, with the consent or at the request of the
         Required Revolving Credit Lenders, the Required Tranche C Term Loan
         Lenders, the Required Tranche D Term Loan Lenders or the Required
         Tranche E Lenders, or in the absence of its own gross negligence or
         wilful misconduct."

                 3.21  Amendments.  Clause (vi) of Section 10.02(b) of the
Credit Agreement is hereby amended to read in its entirety as follows:

                 "(vi)  change any of the provisions of this Section 10.02 or
         the definition of "Required Lenders", "Required Revolving Credit
         Lenders", "Required Tranche C Term Loan Lenders", "Required Tranche D
         Term Loan Lenders" or "Required Tranche E Lenders", or any other
         provision hereof specifying the number or percentage of Lenders
         required to waive, amend or modify any rights hereunder or under any
         other Loan Document or make any determination or grant any consent
         hereunder or thereunder, without the written consent of each Lender;
         or"

                 3.22  Designation of Loans as "Credit Facility".  Section
10.13 of the Credit Agreement is hereby amended to read in its entirety as
follows:

                 "SECTION 10.13.  Designation as Credit Facility.  NCI hereby
         designates each of the Commitments and Loans hereunder as the "Credit
         Facility" under and for all purposes of the Public Note Indentures.
         In that connection, NCI hereby represents and warrants as of the
         Amendment No. 3 Effective Date that there is not currently in effect
         any designation of any other credit facility as a "Credit Facility"
         under any of the Public Note Indentures.  NCI further agrees that,
         until the principal of and interest on all of the Loans have been paid
         in full and all of the Commitments terminated, it will not designate
         any credit facility (other than the Commitments and Loans hereunder
         pursuant to this Section 10.13) as a "Credit Facility" for purposes of
         any of the Public Note Indentures."





                      Amendment No. 3 to Credit Agreement
<PAGE>   14
                                     - 14 -


                 3.23  Supplement to Schedule 2.01.  Schedule 2.01 is hereby
supplemented to set forth the respective Tranche E Commitments of the Lenders
as provided in Schedule 2.01 to this Amendment No. 3.

                 Section 4.  Authorization to Amend Restricted Company
Guarantee and Security Agreement.  Pursuant to Section 7.02(b) of the
Restricted Company Guarantee and Security Agreement and Section 5.02(c) of the
Intercreditor and Collateral Agency Agreement, each of the Lenders signatory
hereto (a) hereby consents to the execution and delivery of an Amendment No. 2
to the Restricted Company Guarantee and Security Agreement in substantially the
form attached hereto as Exhibit A, (b) hereby authorizes the Collateral Agent
to enter into the Second Secured Intercreditor and Collateral Agency Agreement
in substantially the form attached hereto as Exhibit B and (c) hereby consents
to the granting of the Liens with respect to the Collateral to secure the
Restricted Companies' obligations pursuant to the Second Secured Vendor
Financing Agreement.

                 Section 5.  Representations and Warranties.  NCI and each
Restricted Company represents and warrants to the Lenders and the Agents, as to
itself and each of its subsidiaries, that the representations and warranties
set forth in Article IV of the Credit Agreement are true and complete on the
date hereof as if made on and as of the date hereof (or, if any such
representation or warranty is expressly stated to have been made as of a
specific date or as of the date of the Credit Agreement, such representation or
warranty shall be true and correct as of such specific date or as of September
27, 1996, as applicable), and as if each reference in said Article IV to "this
Agreement" included reference to this Amendment No. 3 and as if each reference
in said Article IV to "the Transactions" included reference to the execution
and delivery of this Amendment No. 3.

                 Section 6.  Conditions Precedent.  The consent set forth in
Section 2 hereof, and the amendments set forth in Section 3 hereof, shall
become effective on the date on which each of the following conditions is
satisfied (or waived in accordance with the last paragraph hereof), and on such
date (as provided in Section 2.01(d) of the Credit Agreement, as amended
hereby), the Tranche E Loans shall be made by each of the Tranche E Lenders:

                 (a)  Counterparts of Amendment.  The Administrative Agent (or
         Special Counsel) shall have received from NCI, the Restricted
         Companies, the Arrangers, and such other Lenders as shall be
         sufficient to constitute the "Required Secured Parties" under and as
         defined in the Restricted Company Guarantee and Security Agreement
         (or, if the "Required Vendors" under the Vendor Financing Agreement
         shall not have consented to this Amendment No. 3, such other Lenders
         as shall be sufficient to constitute the "Required Lenders" under the
         Credit Agreement), either (i) a counterpart of this Amendment No.  3
         signed on behalf of such party or (ii) written evidence satisfactory
         to the Administrative Agent (which may include telecopy





                      Amendment No. 3 to Credit Agreement
<PAGE>   15
                                     - 15 -


         transmission of a signed signature page of this Amendment No. 3) that
         such party has signed a counterpart of this Amendment No. 3.

                 For purposes hereof, the Lenders authorized to execute and
         deliver this Amendment No. 3 shall be the Lenders party to the Credit
         Agreement on the date of this Amendment No. 3 (as indicated on the
         Register at the close of business in New York City on such date),
         regardless of whether any one or more of such Lenders shall, by reason
         of an assignment of Loans or Commitments permitted under Section 10.04
         of the Credit Agreement, continue to be a party to the Credit
         Agreement on the Amendment No. 3 Effective Date (and each Lender party
         to the Credit Agreement on the date of this Amendment No. 3 undertakes
         to inform any Person that takes an assignment of all or any portion of
         such Lender's Commitments or Loans of this Amendment No. 3, and none
         of the other parties to the Credit Agreement shall have any
         responsibility to so inform any such Person of this Amendment No. 3).

                 (b)  Opinion of Counsel to Credit Parties.  The Administrative
         Agent (or Special Counsel) shall have received a favorable written
         opinion (addressed to the Administrative Agent and the Lenders and
         dated the Amendment No. 3 Effective Date) of Jones, Day, Reavis &
         Pogue, counsel to the Credit Parties, covering such matters relating
         to the Credit Parties, this Amendment No. 3, the other Loan Documents
         or the Transactions as the Required Lenders shall request (and each
         Credit Party hereby requests such counsel to deliver such opinion).
         To the extent deemed appropriate by the Restricted Companies, internal
         corporate matters in such opinion (such as due incorporation and the
         like) may be rendered in a separate opinion from the General Counsel
         of NCI.

                 (c)  Opinion of Special Counsel.  The Administrative Agent
         shall have received a favorable written legal opinion (addressed to
         the Administrative Agent and the Lenders and dated the Amendment No. 3
         Effective Date) of Special Counsel, with respect to the enforceability
         of this Amendment No. 3 and the Credit Agreement as amended hereby
         (and each of BZW Barclays, The Chase Manhattan Bank, Morgan Guaranty
         Trust Company of New York, NationsBank of Texas, N.A. and The
         Toronto-Dominion Bank, as arrangers of the credit facilities
         contemplated hereby, requests Special Counsel to deliver such
         opinion).

                 (d)  Corporate Matters.  The Administrative Agent (or Special
         Counsel) shall have received such documents and certificates as the
         Administrative Agent or Special Counsel may reasonably request
         relating to the organization, existence and good standing of each
         Credit Party, the authorization of this Amendment No. 3 and any other
         legal matters relating to the Credit Parties, this Amendment No. 3,
         the other Loan Documents or the Transactions, all in form and
         substance reasonably satisfactory to the Administrative Agent and its
         counsel.





                      Amendment No. 3 to Credit Agreement
<PAGE>   16
                                     - 16 -



                 (e)  Financial Officer Certificate.  The Administrative Agent
         (or Special Counsel) shall have received a certificate, dated the
         Amendment No. 3 Effective Date and signed by the President, a Vice
         President or a Financial Officer of the Borrower, confirming
         compliance with the conditions set forth in paragraphs (a) through (c)
         of Section 5.02 of the Credit Agreement on the Amendment No. 3
         Effective Date after giving effect to the Borrowing of Tranche E
         Loans.

                 (f)  Notes.  The Administrative Agent (or Special Counsel)
         shall have received for each Tranche E Lender that shall have
         requested a promissory note, a duly completed and executed promissory
         note for such Lender.

                 (g)  Vendor Financing Agreement Amendment.  The Administrative
         Agent shall have received evidence satisfactory in form and substance
         to it that the Restricted Companies, Motorola, Lehman Commercial
         Paper, Inc., and NTFC Capital shall have entered into an Amendment No.
         3 to the Vendor Financing Agreement in substantially the form of the
         draft thereof dated August 22, 1997, previously delivered to each of
         the Lenders.

                 (h)  Second Secured Vendor Financing Agreement.  The
         Administrative Agent shall have received evidence satisfactory in form
         and substance to it that the Second Secured Vendor Financing
         Agreement, substantially in the form of the draft dated August 22,
         1997, previously delivered to each of the Lenders, shall have been
         duly executed and delivered by NCI, the Restricted Companies and the
         "Vendor Lenders" named therein.

                 (i)  Amendment No. 2 to Restricted Company Guarantee and
         Security Agreement.  Amendment No. 2 to the Restricted Company
         Guarantee and Security Agreement in substantially the form attached as
         Exhibit A shall have been duly executed and delivered by NCI and the
         Restricted Companies.

                 (j)  Second Secured Intercreditor and Collateral Agency
         Agreement.  The Second Secured Intercreditor and Collateral Agency
         Agreement in substantially the form attached as Exhibit B shall have
         been duly executed and delivered by the Restricted Companies, the
         "Vendor Lenders" named therein and the Collateral Agent.

                 (k)  Fees and Expenses.  The Administrative Agent shall have
         received all fees and other amounts due and payable on or prior to the
         Amendment No. 3 Effective Date, including, to the extent invoiced,
         reimbursement or payment of all out-of-pocket expenses required to be
         reimbursed or paid by the Borrower hereunder.

The Administrative Agent shall notify the Borrower and the Lenders of the
Amendment No. 3 Effective Date, and such notice shall be conclusive and
binding.  Notwithstanding the





                      Amendment No. 3 to Credit Agreement
<PAGE>   17
                                     - 17 -


foregoing, the obligations of the Tranche E Lenders to make Tranche E Loans
under the Credit Agreement as amended hereby shall not become effective unless
each of the foregoing conditions is satisfied (or waived pursuant to Section
10.02) at or prior to 3:00 p.m., New York City time, on August 29, 1997 (and,
in the event such conditions are not so satisfied or waived, the consent and
amendments contemplated hereby shall not become effective).

                 None of the foregoing conditions may be waived, amended or
modified except pursuant to an agreement or agreements in writing entered into
by NCI, the Restricted Companies and the Required Lenders or by NCI, the
Restricted Companies and the Administrative Agent with the consent of the
Required Lenders.

                 Section 7.  Miscellaneous.  Except as herein provided, the
Credit Agreement shall remain unchanged and in full force and effect.  This
Amendment No. 3 may be executed in any number of counterparts, all of which
taken together shall constitute one and the same amendatory instrument and any
of the parties hereto may execute this Amendment No. 3 by signing any such
counterpart.  This Amendment No. 3 shall be governed by, and construed in
accordance with, the law of the State of New York.





                      Amendment No. 3 to Credit Agreement
<PAGE>   18
                                     - 18 -


                 IN WITNESS WHEREOF, the parties hereto have caused this
Amendment No. 3 to Credit Agreement to be duly executed and delivered as of the
day and year first above written.

                            NEXTEL COMMUNICATIONS, INC.
                            
                            By      THOMAS J. SIDMAN
                                    -------------------------------
                                    Name:  Thomas J. Sidman
                                    Title: Vice President  
                            
                      RESTRICTED COMPANIES
                      --------------------

                            NEXTEL FINANCE COMPANY (successor to
                                Fleet Call Corporation),
                            
                              By   THOMAS J. SIDMAN               
                                   -------------------------------
                                   Name:   Thomas J. Sidman
                                   Title:  Vice President  
                            
                            ADVANCED MOBILECOMM OF
                              NORTH CAROLINA, INC.
                            AIRLINK COMMUNICATIONS, INC.
                              (successor to TRS, Inc.)
                            AMERICAN MOBILE SYSTEMS,
                              INCORPORATED (successor to Saber
                              Communications, Inc.)
                            DIAL CALL, INC.
                            DIAL DISTANCE, INC.
                            FC NEW YORK, INC. (successor to Metrocom
                              Trunked Radio Communication Systems, Inc.)
                            FCI 900, INC.
                            FLEET CALL OF TEXAS, INC. (successor to
                              FM Tower Company, Metrolink
                              Communications Corporation and National
                              Tower Trunking Systems, Inc.)





                      Amendment No. 3 to Credit Agreement
<PAGE>   19
                                     - 19 -


                            NEXTEL COMMUNICATIONS OF THE
                              MID-ATLANTIC, INC. (successor to Dispatch
                              Communications of Maryland, Inc., Dispatch
                              Communications of Minnesota, Inc., Dispatch
                              Communications of New England, Inc.,
                              Dispatch Communications of Pennsylvania,Inc.)
                            NEXTEL LICENSE HOLDINGS 1, INC.
                            NEXTEL LICENSE HOLDINGS 2, INC.
                              (successor to Comqor, Inc.)
                            NEXTEL LICENSE HOLDINGS 3, INC.
                              (successor to Dial Call Arkansas, Inc.,
                              Custom Radio/Johnson Communications, Inc.,
                              Dial Call Florida, Inc., Dial Call
                              Kentucky, Inc., Dial Call Louisiana, Inc.,
                              Dial Call Texas, Inc., Dial Call
                              Virginia, Inc., Dial Call West Virginia, Inc.
                              and U.S. Digital, Inc.)
                            NEXTEL LICENSE HOLDINGS 4, INC.
                            NEXTEL OF TEXAS, INC. (successor to Fort
                              Worth Communications, Inc.)
                            NEXTEL WEST CORP.
                              (successor to Airwave Communications Corp.
                              (Seattle), C-Call Corporation, Dispatch
                              Communications of Arizona, Inc., ESMR Sub,
                              Inc., Fleet Call of Utah, Inc., Fleet Call
                              West, Inc., Mijac Enterprises, Inc., Mobile
                              Radio of Illinois, Inc., Motorola SF, Inc.,
                              Nextel Hawaii Acquisition Corp.,
                              Nextel Utah Acquisition Corp., Nextel
                              Western Acquisition Corp., OneComm
                              Corporation, N.A., Powerfone
                              Holdings, Inc., Powerfone, Inc.,
                              Smart SMR of Illinois, Inc., Shoreland
                              Communications, Inc. and Spectrum Resources
                              of the Midwest, Inc.)
                            SAFETY NET, INC.
                            SMART SMR, INC.





                      Amendment No. 3 to Credit Agreement
<PAGE>   20
                                     - 20 -


                            SMART SMR OF CALIFORNIA, INC.
                            SMART SMR OF NEW YORK, INC.
                            
                             By THOMAS J. SIDMAN
                                -------------------------------
                                Name:  Thomas J. Sidman
                                Title: Vice President  
                            
                            FORT WORTH TRUNKED RADIO
                             LIMITED PARTNERSHIP
                             
                            By Nextel of Texas,Inc.,
                              a General Partner
                            
                             By THOMAS J. SIDMAN
                                -------------------------------
                                Name:  Thomas J. Sidman
                                Title: Vice President  
                            
                            



                      Amendment No. 3 to Credit Agreement
<PAGE>   21
                                     - 21 -


                                    LENDERS


BARCLAYS BANK, PLC                       THE CHASE MANHATTAN BANK
                                     
                                     
  By    JAMES K. DOWNEY                    By    TRACEY A. NAVIN 
        -----------------------------            -----------------------------
        Name:  James K. Downey                   Name:  Tracey A. Navin 
        Title: Associate Director                Title: Vice President
                                                       
MORGAN GUARANTY TRUST COMPANY            NATIONSBANK OF TEXAS, N.A.
  OF NEW YORK                         
                                     
  By    MARIA D. KRATSIOS                  By
        -----------------------------            -----------------------------
        Name:  Maria D. Kratsios                 Name:
        Title: Vice President                    Title:
                                                       
                                     
                                     
THE TORONTO-DOMINION BANK                TORONTO DOMINION (TEXAS), INC.
                                     
                                     
  By    WARREN FINLAY                      By   WARREN FINLAY         
        -----------------------------           ------------------------------ 
        Name:  Warren Finlay                    Name:  Warren Finlay
        Title: Manager Credit                   Title: Vice President 
                                     
ABN AMRO BANK N.V.,                      AMARA-2 FINANCE LTD.
 NEW YORK BRANCH                     
                                     
  By    FRANCES O. LOGAN                   By   ANDREW WIGNALL
        -----------------------------           -------------------------------
        Name:  Frances O. Logan                 Name:  Andrew Ian Wignall
        Title: Group Vice President             Title: Director
                                     
                                     
                                     
By      WILLIAM S. BENNETT                                             
        -----------------------------
        Name:  William S. Bennett                      
        Title: Vice President                      






                      Amendment No. 3 to Credit Agreement
<PAGE>   22
                                     - 22 -


BANK OF AMERICA NT & SA                   BANK OF MONTREAL
                                          
                                          
   By    JONATHAN M. KITEL                   By   W.T. CALDER
         --------------------------               ---------------------------
         Name:  Jonathan M. Kitel                 Name:  W.T. Calder
         Title: Attorney-in-fact                  Title: Director
                                          
THE BANK OF NOVA SCOTIA                   BANK OF TOKYO-MITSUBISHI
                                            TRUST COMPANY
                                          
   By    J. ALAN EDWARDS                      By   JOHN P. JUDGE
         --------------------------                --------------------------
         Name:  J. Alan Edwards                    Name:  John P. Judge
         Title: Authorized Signatory               Title: VP & CO-HEAD
         
                                                         
                                          
BankBoston, N.A.                            BANKERS TRUST COMPANY
f.k.a. First National Bank of Boston                                          
                                          
  By     CINDY CHEN                         By     ROSEMARY F. DUNNE
         --------------------------                --------------------------
         Name:  Cindy Chen                         Name:  Rosemary F. Dunne
         Title: Director                           Title: Vice President
                                          
                                          
BEAR STEARNS INVESTMENT PRODUCTS INC.     
                                          
                                          
  By     MARC SIMON                   
         --------------------------       
         Name:  Marc Simon                          
         Title:





                      Amendment No. 3 to Credit Agreement
<PAGE>   23
                                     - 23 -


BANQUE PARIBAS (NEW YORK)                    CAPTIVA FINANCE LTD.
                                        
                                        
   By    SALO AIZENBERG                         By    JOHN H. CULLINANE
         -------------------------------              -------------------------
         Name:  Salo Aizenberg                        Name:  John H. Cullinane 
         Title: Vice President                        Title: Director
                                        
   By                                   
                                        
         -------------------------------
         Name:                          
         Title:                         
                                        
CAPTIVA II FINANCE LTD.                      CERES FINANCE LTD.
                                        
                                        
   By    JOHN H. CULLINANE                      By    JOHN H. CULLINANE
         -------------------------------              -------------------------
         Name:  John H. Cullinane                     Name:  John H. Cullinane
         Title: Director                              Title: Director
                                        
CHANG HWA COMMERCIAL BANK,                   CIBC, INC.
  LTD., NEW YORK BRANCH                 
                                        
   By    BRIAN CHEN                             By    DEBORAH STREK
         -------------------------------              -------------------------
         Name:  Brian Chen                            Name:   Deborah Strek
         Title: VP & Deputy General Manager           Title:  Managing Director,
                                                              CIBC Wood Gundy 
                                                               Securities Corp, 
                                                               as Agent
                                                            
                                        
                                        
                                        
CIBC WOOD GUNDY SECURITIES CORP.             CITIBANK, N.A.
                                        
                                        
   By                                           By    CLAUDIO PHILLIPS
         -------------------------------              -------------------------
         Name:                                        Name:  Claudio Phillips
         Title:                                       Title: Attorney-in-Fact





                      Amendment No. 3 to Credit Agreement
<PAGE>   24
                                     - 24 -


CITY NATIONAL BANK                          COMMERZBANK AKTIENZESELLSCHAFT,
                                              NEW YORK BRANCH
                         
                                                By  JURGEN MAHLER
                                                    ---------------------------
                                                    Name:  Jurgen Mahler
                                                    Title: Assistant Vice 
                                                           President 
                 
   By    DAVID BURDGE                           By  G. ROD MCWALTER
         ---------------------------                ---------------------------
         Name:  David Burdge                        Name:  G. Rod McWalter
         Title: Senior Vice President               Title: Vice President
                                                    
                                                    
                                          
CORESTATES BANK, N.A.                       CREDIT SUISSE FIRST BOSTON
                                          
                                          
   By    LYNAE S. YOUNG                        By   TODD C. MORGAN         
         ---------------------------                ---------------------------
         Name:  Lynae S. Young                      Name:  Todd C. Morgan
         Title: Vice President                      Title: Vice President
                                                                               
                                          
                                          
                                               By   JUDITH E. SMITH
                                                    ---------------------------
                                                    Name:  Judith E. Smith
                                                    Title: Director
                                          
CYPRESS TREE INVESTMENT                     DEBT STRATEGIES FUND, INC.
  MANAGEMENT COMPANY, INC.                
As Attorney in fact and on behalf of
First Allmerica Financial Life Insurance
Company Inc.         
                                 
   By    JOHN W. FRASER                        By   R. DOUGLAS HENDERSON
         ---------------------------                ---------------------------
         Name:   John W. Fraser                     Name:   R. Douglas Henderson
         Title:  Managing Director                  Title:  Authorized Signatory
                                          
                                          
DLJ CAPITAL FUNDING, INC.                   FIRST NATIONAL BANK OF BOSTON
                                          
                                          
   By    NANCY C. UNRATH                       By
         ---------------------------                ---------------------------
         Name: Nancy C. Unrath                      Name:
         Title:                                     Title:
                                          




                      Amendment No. 3 to Credit Agreement
<PAGE>   25
                                     - 25 -


<TABLE>
<S>                                                <C>
FIRST UNION NATIONAL BANK                          FLEET NATIONAL BANK
                                                 
                                                 
                                                        
   By    ROBERT E. HEALY                              By   ALEXANDER G. IVANOV
         -------------------------                         ---------------------------------------
         Name: Robert E. Healy                             Name: Alexander G. Ivanov
         Title: SVP                                        Title: Vice President
                                                 
FUJI BANK, LTD.                                    GOLDMAN SACHS CREDIT
                                                     PARTNERS L.P.
                                                 
                                                 
   By    TEIJI TERAMOTO                               By   STEPHEN J. MCGUINNESS                  
         -------------------------                         ---------------------------------------
         Name: Teitji Teramoto                             Name: Stephen J. McGuinness            
         Title: Vice President & Manager                   Title: Authorized Signatory            
                                                                                                  
                                                                 
                                                 
INDOSUEZ CAPITAL FUNDING II, LTD.                  INDOSUEZ CAPITAL FUNDING III, LTD.
By:  Indosuez Capital as Portfolio Advisor         By:  Indosuez Capital as Portfolio Advisor
                                                 
                                                 
                                                        
   By    FRANCOIS BERTHELOT                           By   FRANCOIS BERTHELOT                     
         ------------------------                          ---------------------------------------
         Name: Francois Berthelot                          Name: Francois Berthelot
         Title: Vice President                             Title: Vice President
                                                 
INDUSTRIAL BANK OF JAPAN, LIMITED                  ING BARING (U.S.) CAPITAL
                                                     CORPORATION
                                                 
                                                 
   By    JEFFREY COLE                                 By   JOAN M. CHIAPPE                          
         ------------------------                          ---------------------------------------  
         Name: Jeffrey Cole                                Name: Joan M. Chiappe                   
         Title: Senior Vice President                      Title: Vice President                   
                                                                                                     
                                                                   
</TABLE>                                         
                                                 
                                                 



                      Amendment No. 3 to Credit Agreement
<PAGE>   26
                                     - 26 -




KEYBANK CORPORATE CAPITAL INC.            KOREA FIRST BANK, LOS ANGELES
                                            AGENCY
                                    
                                    
   By    TIM WILLARD                         By   MR. CHANG HEE NAM         
         ---------------------------              --------------------------
         Name: Tim Willard                        Name: Mr. Chang Hee Nam   
         Title: Corporate Banking Officer         Title: Agent and General   
                                                         Manager            
                                                                            
                                                        
                                    
KZH HOLDING CORPORATION III               LEHMAN COMMERCIAL PAPER INC.
                                    
                                    
                                              
   By    VIRGINIA R. CONWAY                  By   MICHELE SWANSON           
         ---------------------------              --------------------------
         Name: Virginia R. Conway                 Name: Michele Swanson
         Title: Authorized Agent                  Title: Authorized Signatory
                                    
LTCB TRUST COMPANY                        MEESPIERSON CAPITAL CORP.
                                    
                                    
                                              
   By    SHUICHI TAJIMA                      By   CLAUDIA J. CHIFOS          
         ---------------------------              ---------------------------
         Name: Shuishi Tajima                     Name: Claudia J. Chifos
         Title: Senior Vice President             Title: Authorized Signatory
                                    
MERITA BANK LTD                           MERRILL LYNCH DEBT STRATEGIES
                                            PORTFOLIO

                                            By:  Merrill Lynch Asset Management,
                                                   L.P., as Investment Advisor
                                    
   By    ERIC I. MANN                       By   R. DOUGLAS HENDERSON       
         ---------------------------              ---------------------------
         Name: Eric I. Mann                       Name: R. Douglas Henderson
         Title: Vice President                    Title: Authorized Signatory
                                    
                                    
                                    
   By    CLIFFORD ABRAMSKY           
         --------------------------- 
         Name: Clifford Abramsky     
         Title: Vice President       
                                     





                      Amendment No. 3 to Credit Agreement
<PAGE>   27
                                     - 27 -


<TABLE>
 <S>                                      <C>
 MERRILL LYNCH PRIME RATE                  MERRILL LYNCH SENIOR FLOATING
   PORTFOLIO                                 RATE FUND, INC.

    By:  Merrill Lynch Asset Management,
         L.P., as Investment Advisor                      
                                  
                                                
    By    R. DOUGLAS HENDERSON                By   R. DOUGLAS HENDERSON
          ------------------------                 ----------------------------------------
          Name: R. Douglas Henderson               Name: R. Douglas Henderson
          Title: Authorized Signatory              Title: Authorized Signatory
                                  
 THE MITSUBISHI TRUST AND BANKING          ML CBO IV (CAYMAN) LTD.
   CORPORATION                    
                                           By      Protective Asset Management, L.L.C.
                                                   as Collateral Manager
                                  
    By    TOSHIHIRO HAYASHI       
          ------------------------
          Name: Toshihiro Hayashi                
          Title: Senior Vice President     By      JAMES DONDERO                           
                                                   ----------------------------------------
                                                   Name: James Dondero, CFA, CPA
                                                   Title: President - Protective
                                                          Asset Management Company
                                  
 NATIONSBANK, OF TEXAS, N.A.               THE NIPPON CREDIT BANK, LTD.
                                  
                                  
                                                
    By    JENNIFER R. ZYDNEY                  By
          ------------------------                 ----------------------------------------
          Name: Jenifer R. Zydney                  Name:
          Title: Vice President                    Title:
                                  
 OCTAGON CREDIT INVESTORS                  PAMCO CAYMAN LTD.
                                           By:  Protective Asset Management, L.L.C.,
                                                  as Collateral Manager
                                  
    By    RICHARD W. STEWART      
          ------------------------
          Name: Richard W. Stewart             By  JAMES DONDERO                            
          Title: Managing Director                 ---------------------------------------- 
                                                   Name: James Dondero, CFA, CPA            
                                                   Title: President - Protective
                                                          Asset Management Company          
                                                                                            
</TABLE>                          





                      Amendment No. 3 to Credit Agreement
<PAGE>   28
                                     - 28 -



<TABLE>
<S>                                              <C>
PNC BANK, NATIONAL ASSOCIATION                     COOPERATIEVE CENTRALE
                                                     RAIFFEISEN-BOERENLEENBANK
                                                     B.A., "RABOBANK NEDERLAND",
                                                     NEW YORK BRANCH
   By    STEPHEN J. MCGEHRIN                                      
         -------------------------             
         Name: Stephen J. McGehrin                      
         Title: Vice President                        By   ALAN E. MCLINTOCK
                                                           --------------------
RESTRUCTURED OBLIGATIONS BACKED                            Name: Alan E. McLintock
  BY SENIOR ASSETS B.V.                                    Title: Vice President
                                               
By:  Chancellor LGT Senior Secured             
         Management, Inc., as Portfolio Advisor          
                                                      By   W. PIETER C. KODDE
                                                           --------------------
                                                           Name: W. Pieter C. Kodde
By                                                         Title: Vice President
     -----------------------------                               
     Name:                                     
     Title:                                    
                                               
ROYAL BANK OF CANADA                           
                                               
                                               
   By   JOHN P. PAGE                           
        --------------------------             
         Name: John P. Page                    
         Title: Sr. Manager                    
                                               
SENIOR HIGH INCOME PORTFOLIO, INC.                 STRATA FUNDING LTD.
                                               
                                               
   By  R. DOUGLAS HENDERSON                           By   JOHN H. CULLINANE
       ---------------------------                         --------------------
         Name: R. Douglas Henderson                        Name: John H. Cullinane
         Title: Authorized Signatory                       Title: Director
                                               
</TABLE>




                      Amendment No. 3 to Credit Agreement
<PAGE>   29
                                     - 29 -






THE SUMITOMO BANK, LIMITED                 THE SUMITOMO TRUST & BANKING
  NEW YORK BRANCH                            COMPANY LTD., NEW YORK BRANCH
                                         
                                         
   By    JOHN C. KISSINGER                    By     
         ----------------------                   --------------------------
         Name: John C. Kissinger                   Name:
         Title: Joint General Manager              Title:
                                         
                                         
                                              By            
                                                  --------------------------
                                                   Name:
                                                   Title:
                                         
                                         
U.S. BANK OF WASHINGTON, N.A.              VAN KAMPEN AMERICAN CAPITAL
                                             PRIME RATE INCOME TRUST
                                         
   By   GARY EGBERT                      
        -----------------------          
         Name: Gary Egbert                    By  JEFFREY W. MAILLET
         Title: VP                                --------------------------
                                                   Name: Jeffrey W. Maillet
                                                   Title: Senior Vice President
                                                          & Director
                                         





                      Amendment No. 3 to Credit Agreement
<PAGE>   30

                                 Schedule 2.01

                             Tranche E Commitments

                  (The Commitments set forth below are subject
                 to adjustment as contemplated in Section 3.02
                  of Amendment No. 3 to the Credit Agreement)




Commitments                          Lenders
- -----------                          -------

15,000,000.00                        Barclays Bank, PLC
20,000,000.00                        The Chase Manhattan Bank
15,000,000.00                        Morgan Guaranty Trust Company of New York
15,000,000.00                        NationsBank of Texas, N.A.
25,000,000.00                        The Toronto-Dominion Bank
 5,000,000.00                        ABN-AMRO Bank N.V., New York Branch
 5,000,000.00                        Bank of America NT & SA
 5,000,000.00                        Bank of Boston N.A.
 5,000,000.00                        Bank of Montreal
 5,000,000.00                        Bank of Nova Scotia
 5,000,000.00                        Bank of Tokyo-Mitsubishi Trust Company
 5,000,000.00                        Bankers Trust Company
 5,000,000.00                        Bear Stearns Investment Products, Inc.
 5,000,000.00                        CIBC Wood Gundy Securities Corp.
 5,000,000.00                        Citibank, N.A.
 5,000,000.00                        Commerzbank Aktiengesellschaft,
                                       New York Branch
 5,000,000.00                        CoreStates Bank, N.A.
 5,000,000.00                        Credit Suisse First Boston
 5,000,000.00                        Donaldson, Lufkin & Jenrette
 5,000,000.00                        First Union National Bank
 5,000,000.00                        Fuji Bank, Ltd.
 5,000,000.00                        Goldman Sachs Credit Partners L.P.
 5,000,000.00                        Indosuez Capital Funding II, Ltd.
 5,000,000.00                        Industrial Bank of Japan, Limited
 5,000,000.00                        ING Baring (U.S.) Capital Corporation
 5,000,000.00                        Keybank Corporate Capital Inc.
 5,000.000.00                        KZH Holding Corporation III
 5,000,000.00                        Lehman Commercial Paper Inc.
 5,000,000.00                        LTCB Trust Company

                                     




                                 Schedule 2.01
<PAGE>   31
                                     - 2 -




<TABLE>
<CAPTION>

Commitments                      Lenders
- -----------                      -------
 <S>                             <C>
 5,000,000.00                    Meespierson Capital Corp.
 5,000,000.00                    Merita Bank Ltd
 5,000,000.00                    Merrill Lynch Debt Strategies Portfolio
 5,000,000.00                    The Mitsubishi Trust and Banking Corporation
 5,000,000.00                    Octagon Credit Investors
 5,000,000.00                    Cooperatieve Centrale Raiffeisen-Boerenleenbank B.A.,
                                   "Rabobank Nederland", New York Branch
 5,000,000.00                    Royal Bank of Canada
 5,000,000.00                    Van Kampen American Capital Prime Rate 
                                  Income Trust
</TABLE>                             
                                     
                                     
                                     
                                     

                                 Schedule 2.01
<PAGE>   32
                                                                       EXHIBIT A



                     AMENDMENT NO. 2 TO RESTRICTED COMPANY
                        GUARANTEE AND SECURITY AGREEMENT


                 AMENDMENT NO. 2 TO RESTRICTED COMPANY GUARANTEE AND SECURITY
AGREEMENT dated as of August 29, 1997 between NEXTEL FINANCE COMPANY, a
corporation duly organized and validly existing under the laws of the State of
Delaware (the "Borrower"); each of the subsidiaries of Nextel Communications,
Inc. listed on the signature pages hereto under the caption "GUARANTORS"
(individually, a "Guarantor" and, collectively, the "Guarantors" and, together
with the Company, the "Restricted Companies"); and THE CHASE MANHATTAN BANK, as
collateral agent for the Vendors and Lenders party to the Loan Agreements
referred to below (in such capacity, together with its successors in such
capacity, the "Collateral Agent").

                 Nextel Communications, Inc. and the Restricted Companies are
parties to (i) an Amended, Restated and Consolidated Credit Agreement dated as
of September 27, 1996 (as modified and supplemented and in effect from time to
time, the "Vendor Financing Agreement") with Motorola, Inc., a Delaware
corporation ("Motorola"), and NTFC Capital Corporation, a Delaware corporation
("NTFC Capital" and, together with Motorola, the "Vendors"), providing, subject
to the terms and conditions thereof, for loans to be made by Motorola and NTFC
Capital to the Borrower in an aggregate principal amount not exceeding
$345,000,000 and (ii) a Credit Agreement dated as of September 27, 1996 (as
modified and supplemented and in effect from time to time, the "Credit
Agreement" and, together with the Vendor Financing Agreement, the "Loan
Agreements"), providing, subject to the terms and conditions thereof, for
extensions of credit (by means of loans and letters of credit) to be made by
the Lenders named therein (collectively, together with any entity that becomes
a "Lender" party to the Credit Agreement after the date thereof as provided
therein, the "Lenders") to the Borrower in an aggregate principal or face
amount not exceeding $1,655,000,000 (which, in the circumstances contemplated
by Section 7.01(f) thereof, may be increased to $1,905,000,000).

                 The Restricted Companies and the Collateral Agent are parties
to a Guarantee and Security Agreement dated as of September 27, 1996 (as
modified and supplemented and in effect from time to time, the "Restricted
Company Guarantee and Security Agreement") pursuant to which the Guarantors
have guaranteed the Guaranteed Obligations (as therein defined), and the
Restricted Companies have pledged and granted a security interest in the
Collateral (as so defined) as security for the Secured Obligations (as so
defined).





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   33
                                     - 2 -


                 Concurrently with the execution and delivery hereof, (x) the
Vendor Financing Agreement is being amended to provide for an increase of
$50,000,000 in the amount of "Tranche A Loans" to be made thereunder by
Motorola (which increase is to be secured on a basis equal and ratable with the
existing Secured Obligations under the Restricted Company Guarantee and
Security Agreement), (y) the Credit Agreement is being amended to provide for
the making of "Tranche E Loans" thereunder in an aggregate amount equal to
$250,000,000 as contemplated by Section 7.01(f) thereof (which "Tranche E
Loans" are to be secured on a basis equal and ratable with the existing Secured
Obligations under the Restricted Company Guarantee and Security Agreement), and
(z) NCI, the Restricted Companies and, Motorola (as the initial "Vendor Lender"
party thereto are entering into a Second Secured Vendor Financing Agreement
dated as of August 29, 1997 (the "Second Secured Vendor Financing Agreement"),
providing for the making by Motorola to the Borrower of "Tranche D Loans" in an
aggregate principal amount equal to $200,000,000 (which "Tranche D Loans" are
to be secured on a basis junior to the existing Secured Obligations under the
Restricted Company Guarantee and Security Agreement).

                 In that connection, the Restricted Companies and the
Collateral Agent (with the consent of the appropriate "Secured Parties" as
required by Section 7.02(b) of the Restricted Company Guarantee and Security
Agreement and Section 5.02(c) of the Intercreditor and Collateral Agency
Agreement) wish to amend the Restricted Company Guarantee and Security
Agreement in certain respects, and accordingly, the parties hereto hereby agree
as follows:

                 Section 1.  Definitions.  Except as otherwise defined in this
Amendment No. 2 to Restricted Company Guarantee and Security Agreement, terms
defined in the Restricted Company Guarantee and Security Agreement are used
herein as defined therein.

                 Section 2.  Amendments.  Subject to the satisfaction of the
condition precedent specified in Section 4 below, but effective as of the date
hereof, the Restricted Company Guarantee and Security Agreement shall be
amended as follows:

                 2.01  References Generally.  References in the Restricted
Company Guarantee and Security Agreement to "this Agreement" (and indirect
references such as "hereunder", "hereby", "herein" and "hereof") shall be
deemed to be references to the Restricted Company Guarantee and Security
Agreement as amended hereby.

                 2.02  Definitions.  Section 1.01 of the Restricted Company
Guarantee and Security Agreement is hereby amended by adding the following new
definitions (to the extent not already included in said Section 1.01) and
inserting the same in the appropriate alphabetical locations and amending the
following definitions (to the extent already included in said Section 1.01), as
follows:





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   34
                                     - 3 -



                 "Event of Default" means (x) an "Event of Default" under and
         as defined in the Credit Agreement or an "Event of Default" under and
         as defined in the Vendor Financing Agreement and (y) after the Senior
         Termination Date, an "Event of Default" under and as defined in the
         Second Secured Vendor Financing Agreement.

                 "Required Secured Parties" means (x) at any time prior to the
         Senior Termination Date, Secured Parties having Loans, LC Exposure and
         unused Commitments under the respective Loan Agreements representing
         at least 51% of the sum of the total Loans, LC Exposure and unused
         Commitments at such time and (y) at any time after the Senior
         Termination Date, Secured Parties having loans and unused commitments
         under the Second Secured Vendor Financing Agreement representing at
         least 51% of the sum of the total of such loans and commitments at
         such time.

                 "Second Secured Intercreditor and Collateral Agency Agreement"
         has the meaning assigned to such term in the Loan Agreements.

                 "Second Secured Obligations" means, collectively, (a) in the
         case of the Borrower, the principal of and interest on the loans made
         by the Secured Parties to the Borrower pursuant to the Second Secured
         Vendor Financing Agreement, (b) in the case of each Guarantor, all
         obligations of such Guarantor in respect of its Guarantee under
         Article II of the obligations of the Borrower under the Second Secured
         Vendor Financing Agreement and, after the Senior Termination Date, of
         the obligations of each Restricted Company under the Security
         Documents and (c) in the case of each Restricted Company, but only
         after the Senior Termination Date, all other obligations of such
         Restricted Company to the Secured Parties and the Agents hereunder.

                 "Second Secured Vendor Financing Agreement" has the meaning
         assigned to such term in the Loan Agreements.

                 "Secured Obligations" means, collectively, the Senior Secured
         Obligations and the Second Secured Obligations.
 
                 "Secured Parties" means, collectively, (i) the Vendors, (ii)
         the Lenders and (iii) the Vendor Lenders from time to time party to
         the Second Secured Vendor Financing Agreement.  This definition shall,
         effective upon the execution and delivery of Amendment No. 2 hereto,
         override the definition of the term "Secured Parties" set forth in the
         preamble to this Agreement.

                 "Senior Secured Obligations" means, collectively, (a) in the
         case of the Borrower, the principal of and interest on the Loans made
         by the Secured Parties to





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   35
                                     - 4 -


         the Borrower, all LC Disbursements and all other amounts from time to
         time owing to the Secured Parties or the Agents by the Borrower under
         the Loan Documents or any Hedging Agreement, (b) in the case of each
         Guarantor, all obligations of such Guarantor in respect of its
         Guarantee under Article II of the obligations of the Borrower under
         the Loan Documents and (c) in the case of each Restricted Company, all
         other obligations of such Restricted Company to the Secured Parties
         and the Agents hereunder.

                 "Senior Termination Date" means the date (or the time on such
         date) upon which the Senior Secured Obligations shall have been paid
         in full and the Commitments shall have been terminated.

                 2.03  The Guarantee.  Sections 2.01 and 2.05, respectively, of
the Restricted Company Guarantee and Security Agreement are hereby amended to
read in their entirety as follows:

                 "SECTION 2.01.  The Guarantee.  The Guarantors hereby jointly
         and severally guarantee to each Secured Party and the Agents and their
         respective successors and assigns the prompt payment in full when due
         (whether at stated maturity, by acceleration or otherwise) of the
         principal of and interest on the Loans made by the Secured Parties to
         the Borrower, all LC Disbursements and all other amounts from time to
         time owing to the Secured Parties or either Agent by the Borrower
         under the Loan Agreements or any other Loan Document, all obligations
         of the Borrower to any Secured Party under any Hedging Agreement and
         all obligations of the Borrower to any Secured Party under the Second
         Secured Vendor Financing Agreement, in each case strictly in
         accordance with the terms thereof (such principal, interest, other
         amounts and obligations being herein collectively called the
         "Guaranteed Obligations").  The Guarantors hereby further jointly and
         severally agree that if the Borrower shall fail to pay in full when
         due (whether at stated maturity, by acceleration or otherwise) any of
         the Guaranteed Obligations, the Guarantors will promptly pay the same,
         without any demand or notice whatsoever, and that in the case of any
         extension of time of payment or renewal of any of the Guaranteed
         Obligations, the same will be promptly paid in full when due (whether
         at extended maturity, by acceleration or otherwise) in accordance with
         the terms of such extension or renewal.

                 SECTION 2.05.  Remedies.  The Guarantors jointly and severally
         agree that, as between the Guarantors and the Secured Parties, the
         obligations of the Borrower under the Loan Agreements and the Second
         Secured Vendor Financing Agreement may be declared to be forthwith due
         and payable as provided in Article VIII of the respective Loan
         Agreements or Second Secured Vendor Financing Agreement, as the





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   36
                                     - 5 -


         case may be (and shall be deemed to have become automatically due and
         payable in the circumstances provided in said Articles VIII) for
         purposes of Section 2.01 notwithstanding any stay, injunction or other
         prohibition preventing such declaration (or such obligations from
         becoming automatically due and payable) as against the Borrower and
         that, in the event of such declaration (or such obligations being
         deemed to have become automatically due and payable), such obligations
         (whether or not due and payable by the Borrower) shall forthwith
         become due and payable by the Guarantors for purposes of said Section
         2.01."

                 2.04  Sale Proceeds Reinvestment Account.  Paragraph (a) of
Section 5.01 of the Restricted Company Guarantee and Security Agreement is
hereby amended to read in its entirety as follows:

                 "(a)  prior to the Senior Termination Date, the Restricted
         Companies shall deposit into the Sale Proceeds Reinvestment Account,
         the Net Cash Payments of any Disposition (as each of such capitalized
         terms is defined in the respective Loan Agreements on the date hereof
         and in the Second Secured Vendor Financing Agreement on the date
         thereof) that, pursuant to clause (y) of Section 2.09(b)(ii) of the
         respective Loan Agreements, the Restricted Companies elect to deliver
         to the Collateral Agent pending reinvestment of such Net Cash Payments
         into replacement assets (and, after the Senior Termination Date, the
         Restricted Companies shall deposit into the Sale Proceeds Reinvestment
         Account, the Net Cash Payments of any such Disposition that, pursuant
         to clause (y) of Section 2.09(b)(ii) of the Second Secured Vendor
         Financing Agreement, the Restricted Companies elect to deliver to the
         Collateral Agent pending reinvestment of such Net Cash Payments into
         replacement assets);"

                 2.05  Tax Proceeds Reinvestment Account.  Paragraph (c) of
Section 5.01 of the Restricted Company Guarantee and Security Agreement is
hereby amended to read in its entirety as follows:

                 "(c)  the Restricted Companies shall deposit into the Tax
         Proceeds Account, that portion of the cash payment received by the
         Restricted Companies directly or indirectly in connection with any
         Disposition (as such term in defined in the respective Loan Agreements
         on the date hereof and in the Second Secured Vendor Financing
         Agreement on the date thereof) that represents the income or other
         taxes estimated to be payable by the Restricted Companies as a result
         of such Disposition and that are deducted in determining the amount of
         "Net Cash Payments" (as so defined) with respect to such Disposition;"





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   37
                                     - 6 -


                 2.06  Application of Monies in Collateral Accounts.  Section
5.02 of the Restricted Company Guarantee and Security Agreement is hereby
amended to read in its entirety as follows:

                 "SECTION 5.02.  Application of Monies in Collateral Accounts.
         The balance from time to time in the Collateral Accounts shall
         constitute part of the Collateral hereunder, shall not constitute
         payment of the Secured Obligations until applied to the Secured
         Obligations as hereinafter provided and shall be released to the
         Restricted Companies (or otherwise be subject to withdrawal) only as
         follows:

                          (a)  prior to the Senior Termination Date, monies and
                 investments in the Sale Proceeds Reinvestment Account may be
                 withdrawn only in connection with a reinvestment transaction
                 permitted under Section 2.09(b)(ii) of the respective Loan
                 Agreements, or for application to the prepayment of Loans (or
                 cover for Letters of Credit) as contemplated by said Section
                 2.09(b)(ii) (and, after the Senior Termination Date, such
                 monies and investments may be withdrawn only in connection
                 with a reinvestment transaction permitted under Section
                 2.09(b)(ii) of the Second Secured Vendor Financing Agreement
                 as contemplated by said Section 2.09(b)(ii)), provided that
                 (without the consent of the Required Secured Parties) the
                 Collateral Agent shall not be obligated to release such monies
                 for application to a reinvestment transaction at any time
                 after the occurrence and during the continuance of any Event
                 of Default;

                          (b)  monies and investments in the Casualty Event
                 Proceeds Account may be withdrawn only in connection with the
                 replacement, restoration and repair of the property affected
                 by such Casualty Event (the "Damaged Property"), or, prior to
                 the Senior Termination Date, for application to the prepayment
                 of Loans (or cover for Letters of Credit) pursuant to Section
                 2.09(a) of the Loan Agreements in such manner as the Borrower
                 shall elect (and, after the Senior Termination Date, for
                 application to the prepayment of loans under the Second
                 Secured Vendor Financing Agreement pursuant to Section 2.09(a)
                 thereof in such manner as the Borrower shall elect), and if
                 the respective Restricted Company elects to so replace or
                 restore and repair Damaged Property, any such monies shall be
                 advanced to such Restricted Company by the Collateral Agent in
                 periodic installments upon compliance by such Restricted
                 Company with such reasonable conditions to disbursement as may
                 be imposed by the Collateral Agent, including, but not limited
                 to, reasonable retention amounts and receipt of lien releases,
                 provided that (without the consent of the Required Secured
                 Parties) the Collateral Agent shall not be obligated to
                 release such monies for application to any such





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   38
                                     - 7 -


                 replacement, restoration, repair or prepayment at any time
                 after the occurrence and during the continuance of any Event
                 of Default;

                          (c)  prior to the Senior Termination Date, monies and
                 investments in the Tax Proceeds Account may be withdrawn only
                 in connection with the payment of taxes as contemplated by the
                 definition of "Net Cash Payments" in the respective Loan
                 Agreements, or for application to the prepayment of Loans (or
                 cover for Letters of Credit) as contemplated by Section
                 2.09(b)(ii) thereof (and, after the Senior Termination Date,
                 such monies and investments may be withdrawn only in
                 connection with the payment of taxes as contemplated by the
                 definition of "Net Cash Payments" in the Second Secured Vendor
                 Financing Agreement, or for application to the prepayment of
                 Loans under the Second Secured Vendor Financing Agreement, as
                 contemplated by Section 2.09(b)(ii) thereof), provided that
                 (without the consent of the Required Secured Parties) the
                 Collateral Agent shall not be obligated to release such monies
                 for application to the payment of taxes at any time after the
                 occurrence and during the continuance of any Event of Default;

                          (d)  monies and investments in the Letter of Credit
                 Account may be applied only to the payment of LC Disbursements
                 for which the respective Issuing Banks have not been
                 reimbursed by the Borrower or, but only with the consent of
                 the Required Revolving Credit Lenders, to the payment of other
                 Secured Obligations and, after the payment in full of all LC
                 Disbursements and the expiration or termination of all Letters
                 of Credit, to the payment of any other Secured Obligations as
                 shall at the time be payable hereunder; and

                          (e)  monies and investments in the Concentration
                 Account may be withdrawn only (I) in connection with remitting
                 the same to bank deposit accounts (such as payroll and other
                 accounts) maintained by the Restricted Companies for use in
                 the ordinary course of business, (II) to make Capital
                 Expenditures, (III) prior to the Senior Termination Date to
                 make acquisitions and investments permitted under Section 7.04
                 of the respective Loan Agreements (and, after the Senior
                 Termination Date, to make acquisitions and investments
                 permitted under Section 7.04 of the Second Secured Vendor
                 Financing Agreement), (IV) prior to the Senior Termination
                 Date to make Restricted Payments permitted under Section 7.05
                 of the respective Loan Agreements (and, after the Senior
                 Termination Date, to make Restricted Payments permitted under
                 Section 7.05 of the Second Secured Vendor Financing
                 Agreement), or (V) prior to the Senior Termination Date to
                 make payments or prepayments of principal, interest or other
                 amounts in respect of Indebtedness (including Loans) or
                 Hedging Agreements permitted under the





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   39
                                     - 8 -


                 respective Loan Agreements (and, after the Senior Termination
                 Date, to make payments or prepayments of principal, interest
                 or other amounts in respect of Indebtedness (including the
                 loans under the Second Secured Vendor Financing Agreement) or
                 Hedging Agreements permitted under the Second Secured Vendor
                 Financing Agreement).

         In connection with any release of monies in any of the Collateral
         Accounts described above, the Collateral Agent shall be entitled to
         rely upon a certificate of a Financial Officer (and upon such other
         evidence, if any, as the Collateral Agent shall deem appropriate).  At
         any time following the occurrence and during the continuance of an
         Event of Default, the Collateral Agent may (and, if instructed by the
         Required Secured Parties shall) in its (or their) discretion apply or
         cause to be applied (subject to collection) the balance from time to
         time outstanding to the credit of any of the Collateral Accounts to
         the payment of the Secured Obligations in the manner specified in
         Section 6.09."

                 2.07  Other Financing Statements and Liens.  Section 6.02 of
the Restricted Company Guarantee and Security Agreement is hereby amended to
read in its entirety as follows:

                 "SECTION 6.02.  Other Financing Statements and Liens.  Except
         as otherwise permitted under Section 7.02 of the respective Loan
         Agreements or the Second Secured Vendor Financing Agreement, without
         the prior written consent of the Collateral Agent (granted with the
         authorization of the Required Secured Parties), no Restricted Company
         shall file or suffer to be on file, or authorize or permit to be filed
         or to be on file, in any jurisdiction, any financing statement or like
         instrument with respect to the Collateral in which the Collateral
         Agent is not named as the sole secured party for the benefit of the
         Secured Parties."

                 2.08  Removals.  Section 6.07 of the Restricted Company
Guarantee and Security Agreement is hereby amended to read in its entirety as
follows:

                 "SECTION 6.07.  Removals, Etc.  Without at least 30 days'
         prior written notice to the Collateral Agent, no Restricted Company
         shall (i) maintain any of its books and records with respect to the
         Collateral at any office or maintain its principal place of business
         other than at the address for notices to the Borrower specified in
         Section 10.01 of the respective Loan Agreements or the Second Secured
         Vendor Financing Agreement, or at one of the locations identified in
         Annex 3 or in transit from one of such locations to another or (ii)
         change its name, or the name under which it does business, from the
         name shown on the signature pages hereto."





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   40
                                     - 9 -


                 2.09  Application of Proceeds.  Section 6.09 of the Restricted
Company Guarantee and Security Agreement is hereby amended to read in its
entirety as follows:

                 "SECTION 6.09.  Application of Proceeds.  Except as otherwise
         herein expressly provided, the proceeds of any collection, sale or
         other realization of all or any part of the Collateral pursuant
         hereto, and any other cash at the time held by the Collateral Agent
         under Article V or this Article VI, shall be applied by the Collateral
         Agent:

                          First, to the payment of the costs and expenses of
                 such collection, sale or other realization, including
                 reasonable out-of-pocket costs and expenses of the Collateral
                 Agent and the fees and expenses of its agents and counsel, and
                 all expenses incurred and advances made by the Collateral
                 Agent in connection therewith;

                          Next, to the payment in full of the Senior Secured
                 Obligations, in each case equally and ratably in accordance
                 with the respective amounts thereof then due and owing or as
                 the Secured Parties holding the same may otherwise agree;

                          Next, to the payment in full of the Second Secured
                 Obligations, in each case equally and ratably in accordance
                 with the respective amounts thereof then due and owing or as
                 the Secured Parties holding the same may otherwise agree; and

                          Finally, to the payment to the respective Restricted
                 Company, or their respective successors or assigns, or as a
                 court of competent jurisdiction may direct, of any surplus
                 then remaining.

                          As used in this Article VI, "proceeds" of Collateral
         shall mean cash, securities and other property realized in respect of,
         and distributions in kind of, Collateral, including any thereof
         received under any reorganization, liquidation or adjustment of debt
         of the Restricted Companies or any issuer of or obligor on any of the
         Collateral."

                 2.10  Termination.  Section 6.12 of the Restricted Company
Guarantee and Security Agreement is hereby amended to read in its entirety as
follows:

                 "SECTION 6.12.  Termination.  When all Secured Obligations
         shall have been paid in full and the Commitments of the Secured
         Parties under the respective Loan Agreements (and the commitments of
         the Secured Parties under the Second Secured





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   41
                                     - 10 -


         Vendor Financing Agreement) shall have expired or been terminated,
         this Agreement shall terminate, and the Collateral Agent shall
         forthwith cause to be assigned, transferred and delivered, against
         receipt but without any recourse, warranty or representation
         whatsoever, any remaining Collateral and money received in respect
         thereof, to or on the order of the respective Restricted Company.  The
         Collateral Agent shall also execute and deliver to respective
         Restricted Company upon such termination such Uniform Commercial Code
         termination statements and such other documentation as shall be
         reasonably requested by the respective Restricted Company to effect
         the termination and release of the Liens on the Collateral."

                 2.11  Certain Regulatory Requirements.  Section 7.11(a) of the
Restricted Company Guarantee and Security Agreement is hereby amended to read
in its entirety as follows:

                 "(a)  Each Restricted Company shall take all action that the
         Collateral Agent may reasonably request in the exercise of its rights
         and remedies hereunder, which include the right to require such
         Restricted Company to transfer or assign the FCC Licenses or the PUC
         Authorizations to any party or parties.  In furtherance of this right,
         each Restricted Company shall (i) cooperate fully with the Collateral
         Agent in obtaining all approvals and consents from the FCC and each
         other Governmental Authority that the Collateral Agent may deem
         necessary or advisable to accomplish any such transfer or assignment
         of the FCC Licenses or the PUC Authorizations and (ii) prepare,
         execute and file with the FCC and any other Governmental Authority any
         application, request for consent, certificate or instrument that the
         Collateral Agent may deem necessary or advisable to accomplish any
         such transfer or assignment of the FCC Licenses or the PUC
         Authorizations.  If any Restricted Company fails to execute such
         applications, requests for consent, certificates or instruments, the
         clerk of any court that has jurisdiction over the Loan Documents (or,
         after the Senior Termination Date, over the Second Secured Vendor
         Financing Agreement and the Security Documents) may, upon an ex parte
         request by the Collateral Agent, execute and file the same on behalf
         of such Restricted Company."

                 2.12  Additional Guarantors.  Section 7.12 of the Restricted
Company Guarantee and Security Agreement is hereby amended to read in its
entirety as follows:

                 "SECTION 7.12.  Additional Guarantors.  As contemplated by
         Section 6.11(a) of the respective Loan Agreements (and by Section
         6.11(a) of the Second Secured Vendor Financing Agreement), in the
         event that any Restricted Company shall form or acquire any new
         subsidiary after the date hereof, such Restricted Company will cause
         such new subsidiary to execute and deliver to the Collateral Agent a
         Joinder Agreement in the form of Exhibit E to the respective Loan
         Agreements or Exhibit E





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   42
                                     - 11 -


         to the Second Secured Vendor Financing Agreement (and, thereby, to
         become a party to the Loan Agreements and to the Second Secured Vendor
         Financing Agreement as a "Restricted Company" thereunder, and to this
         Agreement, the Intercreditor and Collateral Agency Agreement and the
         Second Secured Intercreditor and Collateral Agency Agreement, as a
         "Guarantor" hereunder and thereunder, and to pledge and grant a
         security interest in its property pursuant to this Agreement to the
         Collateral Agent for the benefit of the Secured Parties).
         Accordingly, upon the execution and delivery of any such Joinder
         Agreement by any such new subsidiary, such new subsidiary shall
         automatically and immediately, and without any further action on the
         part of any Person, become a "Guarantor" under and for all purposes of
         this Agreement, and Annexes 1, 2 and 3 hereto shall be deemed to be
         supplemented in the manner specified in said Joinder Agreements."

                 Section 3.  Representations and Warranties.  Each Restricted
Company represents and warrants to the Secured Parties and the Collateral Agent
that the representations and warranties set forth in Article III of the
Restricted Company Guarantee and Security Agreement are true and complete on
the date hereof as if made on and as of the date hereof (or if any such
representation and warranty is expressly stated to have been made as of a
specific date, as of such date) and as if each reference in said Article III to
"this Agreement" included reference to the Restricted Company Guarantee and
Security Agreement as amended by this Amendment No. 2.

                 Section 4.  Conditions Precedent.  As provided in Section 2
above, the amendments to the Restricted Company Guarantee and Security
Agreement set forth in said Section 2 shall become effective, as of the date
hereof, upon the execution and delivery of this Amendment No. 2 to Restricted
Company Guarantee and Security Agreement by each of the Restricted Companies
and the Collateral Agent.

                 Section 5.  Amendment to Collateral Assignment of Leasehold
Interests.  The Collateral Assignment of Leasehold Interests referred to in the
last sentence of Section 6.13 of the Restricted Company Guarantee and Security
Agreement (as amended hereby) shall be deemed to be amended to the extent
necessary to reference the Second Secured Vendor Financing Agreement and to
include the obligations of the Borrower under the Second Secured Vendor
Financing Agreement as "Secured Obligations" under and as defined therein,
subject to the Second Secured Intercreditor and Collateral Agency Agreement.

                 Section 6.  Miscellaneous.  Except as herein provided, the
Restricted Company Guarantee and Security Agreement shall remain unchanged and
in full force and effect.  This Amendment No. 2 to Restricted Company Guarantee
and Security Agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same amendatory instrument
and any of the parties hereto may execute this Amendment





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   43
                                     - 12 -


No. 2 to Restricted Company Guarantee and Security Agreement by signing any
such counterpart.  This Amendment No. 2 to Restricted Company Guarantee and
Security Agreement shall be governed by, and construed in accordance with, the
law of the State of New York.





                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   44
                                     - 13 -



                 IN WITNESS WHEREOF, the parties hereto have caused this
Amendment No. 2 to Restricted Company Guarantee and Security Agreement to be
duly executed and delivered as of the day and year first above written.

                      NEXTEL COMMUNICATIONS, INC.

                         By
                                                             
                              -------------------------------
                              Name:
                              Title:

          RESTRICTED COMPANIES

                      NEXTEL FINANCE COMPANY (successor to
                        Fleet Call Corporation),

                         By
                                                             
                              -------------------------------
                              Name:
                              Title:

                      ADVANCED MOBILECOMM OF
                        NORTH CAROLINA, INC.
                      AIRLINK COMMUNICATIONS, INC.
                        (successor to TRS, Inc.)
                      AMERICAN MOBILE SYSTEMS,
                        INCORPORATED (successor to Saber
                        Communications, Inc.)
                      DIAL CALL, INC.
                      DIAL DISTANCE, INC.
                      FC NEW YORK, INC. (successor to Metrocom
                        Trunked Radio Communication Systems, Inc.)
                      FCI 900, INC.
                      FLEET CALL OF TEXAS, INC. (successor to
                        FM Tower Company, Metrolink
                        Communications Corporation and National
                        Tower Trunking Systems, Inc.)






                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   45
                                     - 14 -


                            NEXTEL COMMUNICATIONS OF THE
                              MID-ATLANTIC, INC. (successor to Dispatch
                              Communications of Maryland, Inc., Dispatch
                              Communications of Minnesota, Inc., Dispatch
                              Communications of New England, Inc.,
                              Dispatch Communications of Pennsylvania,Inc.)
                            NEXTEL LICENSE HOLDINGS 1, INC.
                            NEXTEL LICENSE HOLDINGS 2, INC.
                              (successor to Comqor, Inc.)
                            NEXTEL LICENSE HOLDINGS 3, INC.
                              (successor to Dial Call Arkansas, Inc.,
                              Custom Radio/Johnson Communications, Inc.,
                              Dial Call Florida, Inc., Dial Call
                              Kentucky, Inc., Dial Call Louisiana, Inc.,
                              Dial Call Texas, Inc., Dial Call
                              Virginia, Inc., Dial Call West Virginia, Inc.
                              and U.S. Digital, Inc.)
                            NEXTEL LICENSE HOLDINGS 4, INC.
                            NEXTEL OF TEXAS, INC. (successor to Fort
                              Worth Communications, Inc.)
                            NEXTEL WEST CORP.
                              (successor to Airwave Communications Corp.
                              (Seattle), C-Call Corporation, Dispatch
                              Communications of Arizona, Inc., ESMR Sub,
                              Inc., Fleet Call of Utah, Inc., Fleet Call
                              West, Inc., Mijac Enterprises, Inc., Mobile
                              Radio of Illinois, Inc., Motorola SF, Inc.,
                              Nextel Hawaii Acquisition Corp.,
                              Nextel Utah Acquisition Corp., Nextel
                              Western Acquisition Corp., OneComm
                            Corporation, N.A., Powerfone
                              Holdings, Inc., Powerfone, Inc.,
                              Smart SMR of Illinois, Inc., Shoreland
                              Communications, Inc. and Spectrum Resources
                              of the Midwest, Inc.)
                            SAFETY NET, INC.
                            SMART SMR, INC.






                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   46
                                     - 15 -


                              SMART SMR OF CALIFORNIA, INC.
                              SMART SMR OF NEW YORK, INC.

                                By
                                                                     
                                      -------------------------------
                                      Name:
                                      Title:

                              FORT WORTH TRUNKED RADIO
                                LIMITED PARTNERSHIP

                              By Nextel of Texas,
                                   a General Partner


                                 By
                                                                     
                                      -------------------------------
                                      Name:
                                      Title:


                     COLLATERAL AGENT

                              THE CHASE MANHATTAN BANK, as
                               Collateral Agent

                              By
                                                                  
                                   ------------------------------------
                                   Name:
                                   Title:






                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement
<PAGE>   47
                                                                       EXHIBIT B



          SECOND SECURED INTERCREDITOR AND COLLATERAL AGENCY AGREEMENT

                 SECOND SECURED INTERCREDITOR AND COLLATERAL AGENCY AGREEMENT
dated as of August 29, 1997 between NEXTEL FINANCE COMPANY, a corporation duly
organized and validly existing under the laws of the State of Delaware (the
"Borrower"); each of the subsidiaries of Nextel Communications, Inc. listed on
the signature pages hereto under the caption "INITIAL GUARANTORS" (the "Initial
Guarantors"); each of the additional entities, if any, that becomes a
"Guarantor" hereunder as contemplated by Section 7.12 of the below-referenced
Restricted Company Guarantee and Security Agreement (each an "Additional
Guarantor" and together with the Initial Guarantors, the "Guarantors"; the
Guarantors together with the Borrower, being herein called the "Restricted
Companies"); MOTOROLA, INC., a Delaware corporation ("Motorola"); each other
VENDOR LENDER that shall at any time, as contemplated by Section 5.04, be
deemed to be a party hereto (collectively, including Motorola the "Vendor
Lenders"); and THE CHASE MANHATTAN BANK, as collateral agent for the Vendors
and for the Lenders referred to below (in such capacity, together with its
successors in such capacity, the "Collateral Agent").

                 Nextel Communications, Inc. ("NCI") and the Restricted
Companies are parties to a Second Secured Vendor Financing Agreement dated as
of August 29, 1997 (as modified and supplemented and in effect from time to
time, the "Second Secured Vendor Financing Agreement") with Motorola and the
other Vendor Lenders referred to therein, providing, subject to the terms and
conditions thereof, for loans to be made by the Vendor Lenders to the Borrower
in an aggregate principal amount not exceeding $200,000,000.  NCI and the
Restricted Companies are also parties to a Vendor Financing Agreement and a
Credit Agreement (as such respective capitalized terms are defined herein),
providing, respectively, for loans and extensions of credit to be made by the
"Lenders" and "Vendors" under such Agreements to the Borrower in an aggregate
principal amount up to but not exceeding, respectively, $395,000,000 and
$1,905,000,000.  This Agreement applies to Motorola solely in its capacity as a
Vendor Lender under the Second Secured Vendor Financing Agreement and shall not
affect, in any way, the rights of Motorola in its capacity as a Vendor under
the Vendor Financing Agreement.

                 The obligations of the Restricted Companies under the Credit
Agreement and the Vendor Financing Agreement are entitled to the benefits of
collateral security provided pursuant to the Security Documents referred to
below.  The parties hereto intend that the collateral security provided by said
Security Documents shall also secure, with a ranking second to that of the
obligations under the Vendor Financing Agreement and Credit Agreement, the
obligations of the Restricted Companies under the Second Secured Vendor
Financing Agreement.  In that connection, the parties hereto wish to provide
for the appointment of the Collateral Agent by the Vendor Lenders and for
certain other matters





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   48
                                     - 2 -



relating to the security interests provided by the Security Documents.
Accordingly, the parties hereto agree as follows:


                                   ARTICLE I

                                  Definitions

                 SECTION 1.01.  Defined Terms.  As used in this Agreement, the
following terms have the meanings specified below:

                 "Affiliate" means, with respect to a specified Person, another
Person that directly, or indirectly through one or more intermediaries,
Controls or is Controlled by or is under common Control with the Person
specified.

                 "Agents" means the Administrative Agent under the Credit
Agreement and the Collateral Agent hereunder.

                 "Applicable Percentage" means with respect to any Vendor
Lender in respect of any indemnity claim under Section 7.03(a) of the
Restricted Company Guarantee and Security Agreement arising out of an action or
omission of the Collateral Agent under any Second Secured Loan Document, the
percentage of the "Tranche D Commitments" under the Second Secured Vendor
Financing Agreement represented by the aggregate amount of such Vendor Lender's
"Tranche D Commitment" under the Second Secured Vendor Financing Agreement.  If
the "Tranche D Commitments" under the Second Secured Vendor Financing Agreement
have terminated or expired, the Applicable Percentages shall be determined
based upon the "Tranche D Commitments" most recently in effect, giving effect
to any assignments.

                 "Commitments" means the "Commitments" of the Lenders under the
Credit Agreement and the "Commitments" of the Vendors under the Vendor
Financing Agreement.

                 "Control" means the possession, directly or indirectly, of the
power to direct or cause the direction of the management or policies of a
Person, whether through the ability to exercise voting power, by contract or
otherwise. "Controlling" and "Controlled" have meanings correlative thereto.

                 "Credit Agreement" means the Credit Agreement dated as of
September 27, 1996, among NCI, the Restricted Companies, the lenders party
thereto, Toronto Dominion (Texas) Inc., as Administrative Agent, and The Chase
Manhattan Bank, as Collateral Agent.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   49
                                     - 3 -




                 "Credit Parties" means NCI and the Restricted Companies.

                 "Default" means any event or condition which constitutes an
Event of Default or which upon notice, lapse of time or both would, unless
cured or waived, become an Event of Default.

                 "Event of Default" means (x) an "Event of Default" under and
as defined in the Credit Agreement or an "Event of Default" under and as
defined in the Vendor Financing Agreement and (y) after the Senior Termination
Date, "Event of Default" under and as defined in the Second Secured Vendor
Financing Agreement.

                 "Governmental Authority" means the government of the United
States of America, any other nation or any political subdivision thereof,
whether state or local, and any agency, authority, instrumentality, regulatory
body, court, central bank or other entity exercising executive, legislative,
judicial, taxing, regulatory or administrative powers or functions of or
pertaining to government.

                 "Hedging Agreement" has the meaning assigned to such term in
the Credit Agreement.

                 "LC Disbursement" has the meaning assigned to such term in the
Credit Agreement.

                 "LC Exposure" has the meaning assigned to such term in the
Credit Agreement.

                 "Lien" means, with respect to any asset, (a) any mortgage,
deed of trust, lien, pledge, hypothecation, encumbrance, charge or security
interest in, on or of such asset, (b) the interest of a vendor or a lessor
under any conditional sale agreement, capital lease or title retention
agreement (or any financing lease having substantially the same economic effect
as any of the foregoing) relating to such asset and (c) in the case of
securities, any purchase option, call or similar right of a third party with
respect to such securities.

                 "Loan Agreements" means, collectively, the Credit Agreement
and the Vendor Financing Agreement.

                 "Loan Documents" means the Loan Agreements, any promissory
notes evidencing Loans under any Loan Agreement and the Security Documents.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   50
                                     - 4 -



                 "Loans" means the "Loans" made by the Lenders to the Borrower
under the Credit Agreement and the "Loans" made by the Vendors to the Borrower
under the Vendor Financing Agreement.

                 "Mortgages" means, collectively, one or more assignments of
lease, mortgages, deeds of trust, deeds to secure debt and the like executed by
a Restricted Company in favor of the Collateral Agent (or a trustee for the
benefit of the Collateral Agent), and covering interests in real property held
by such Restricted Company as collateral security for the Secured Obligations,
in each case in such form as shall be satisfactory to the Collateral Agent.

                 "Person" means any natural person, corporation, limited
liability company, trust, joint venture, association, company, partnership,
Governmental Authority or other entity.

                 "Related Parties" means, with respect to any specified Person,
such Person's Affiliates and the respective directors, officers, employees,
agents and advisors of such Person and such Person's Affiliates.

                 "Required Secured Parties" means (x) at any time prior to the
Senior Termination Date, Secured Parties having Loans, LC Exposure and unused
Commitments under the respective Loan Agreements representing at least 51% of
the sum of the total Loans, LC Exposure and unused Commitments at such time and
(y) at any time after the Senior Termination Date, Secured Parties having loans
and unused commitments under the Second Secured Vendor Financing Agreement
representing at least 51% of the sum of the total of such loans and commitments
at such time.

                 "Required Vendor Lenders" means, at any time, Vendor Lenders
having "Tranche D Loans" and unused "Tranche D Commitments" under the Second
Secured Vendor Financing Agreement representing at least 51% of the sum of the
total "Tranche D Loans" and unused "Tranche D Commitments" at such time.

                 "Restricted Company Guarantee and Security Agreement" means
the Restricted Company Guarantee and Security Agreement dated as of September
27, 1996 between the Restricted Companies and the Collateral Agent.

                 "Second Secured Loan Documents" means the Second Secured
Vendor Financing Agreement, any promissory notes evidencing Loans under the
Second Secured Vendor Financing Agreement and the Security Documents.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   51
                                     - 5 -



                 "Second Secured Obligations" means, collectively, (a) in the
case of the Borrower, the principal of and interest on the loans made by the
Secured Parties to the Borrower pursuant to the Second Secured Vendor Financing
Agreement, (b) in the case of each Guarantor, all obligations of such Guarantor
in respect of its Guarantee under Article II of the Restricted Company Guaranty
and Security Agreement of the obligations of the Borrower under the Second
Secured Vendor Financing Agreement and, after the Senior Termination Date, of
the obligations of each Restricted Company under the Security Documents and (c)
in the case of each Restricted Company, but only after the Senior Termination
Date, all other obligations of such Restricted Company to the Secured Parties
and the Collateral Agent under the Restricted Company Guaranty and Security
Agreement.

                 "Secured Obligations" means, collectively, the Senior Secured
Obligations and the Second Secured Obligations.

                 "Secured Parties" means, collectively, the Lenders from time
to time party to the Credit Agreement, the Vendors from time to time party to
the Vendor Financing Agreement, and the Vendor Lenders from time to time party
to Second Secured Vendor Financing Agreement.

                 "Security Documents" means this Agreement, the Restricted
Company Guarantee and Security Agreement, the Mortgages and all Uniform
Commercial Code financing statements required by any of such instruments to be
filed with respect to the security interests in personal property and fixtures
created pursuant thereto.

                 "Senior Secured Obligations" means, collectively, (a) in the
case of the Borrower, the principal of and interest on the Loans made by the
Secured Parties to the Borrower, all LC Disbursements and all other amounts
from time to time owing to the Secured Parties or the Agents by the Borrower
under the Loan Documents or any Hedging Agreement, (b) in the case of each
Guarantor, all obligations of such Guarantor in respect of its Guarantee under
Article II of the Restricted Company Guaranty and Security Agreement of the
obligations of the Borrower under the Loan Documents and (c) in the case of
each Restricted Company, all other obligations of such Restricted Company to
the Secured Parties and the Agents under the Restricted Company Guaranty and
Security Agreement.

                 "Senior Termination Date" means the date (or the time on such
date) upon which the Senior Secured Obligations shall have been paid in full
and the Commitments shall have been terminated.

                 "subsidiary" means, with respect to any Person (the "parent")
at any date, any corporation, limited liability company, partnership,
association or other entity the accounts of





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   52
                                     - 6 -



which would be consolidated with those of the parent in the parent's
consolidated financial statements if such financial statements were prepared in
accordance with GAAP as of such date, as well as any other corporation, limited
liability company, partnership, association or other entity (a) of which
securities or other ownership interests representing more than 50% of the
ordinary voting power or, in the case of a partnership, more than 50% of the
general partnership interests are, as of such date, owned, controlled or held,
or (b) that is, as of such date, otherwise Controlled, by the parent or one or
more subsidiaries of the parent or by the parent and one or more subsidiaries
of the parent.

                 "Subsidiary" means any subsidiary of the Borrower.

                 "Vendor Equipment Agreements" has the meaning assigned to such
term in the Vendor Financing Agreement.

                 "Vendor Financing Agreement" means the Amended, Restated and
Consolidated Credit Agreement dated as of September 27, 1996, among NCI, the
Restricted Companies, and the vendors party thereto.

                 SECTION 1.02.  Terms Generally.  The definitions of terms
herein shall apply equally to the singular and plural forms of the terms
defined.  Whenever the context may require, any pronoun shall include the
corresponding masculine, feminine and neuter forms.  The words "include",
"includes" and "including" shall be deemed to be followed by the phrase
"without limitation".  The word "will" shall be construed to have the same
meaning and effect as the word "shall".  Unless the context requires otherwise
(a) any definition of or reference to any agreement, instrument or other
document herein shall be construed as referring to such agreement, instrument
or other document as from time to time amended, supplemented or otherwise
modified (subject to any restrictions on such amendments, supplements or
modifications set forth herein), (b) any reference herein to any Person shall
be construed to include such Person's successors and assigns, (c) the words
"herein", "hereof" and "hereunder", and words of similar import, shall be
construed to refer to this Agreement in its entirety and not to any particular
provision hereof, (d) all references herein to Articles, Sections and Exhibits
shall be construed to refer to Articles and Sections of, and Exhibits to, this
Agreement and (e) the words "asset" and "property" shall be construed to have
the same meaning and effect and to refer to any and all tangible and intangible
assets and properties, including cash, securities, accounts and contract
rights.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   53
                                     - 7 -



                                   ARTICLE II

              The Collateral Agent; Appointment by Vendor Lenders

                 Each Vendor Lender hereby irrevocably appoints the Collateral
Agent as its agent and authorizes the Collateral Agent to take such actions on
its behalf and to exercise such powers as are delegated to the Collateral Agent
by the terms of this Agreement and the other Security Documents, together with
such actions and powers as are reasonably incidental thereto.

                 The Chase Manhattan Bank shall have the same rights and powers
in its capacity as a Lender under the Credit Agreement as any other Lender and
may exercise the same as though it were not the Collateral Agent, and The Chase
Manhattan Bank and its Affiliates may accept deposits from, lend money to and
generally engage in any kind of business with any Credit Party or any
subsidiary or other Affiliate of any thereof as if it were not the Collateral
Agent hereunder.

                 The Collateral Agent shall not have any duties or obligations
except those expressly set forth in this Agreement, the existing intercreditor
agreement and the other Security Documents.  Without limiting the generality of
the foregoing, (a) the Collateral Agent shall not be subject to any fiduciary
or other implied duties, regardless of whether a Default has occurred and is
continuing, (b) the Collateral Agent shall not have any duty to take any
discretionary action or exercise any discretionary powers, except discretionary
rights and powers expressly contemplated by this Agreement and the other
Security Documents that the Collateral Agent is required to exercise in writing
by the Required Secured Parties, and (c) except as expressly set forth herein
and in the other Security Documents, the Collateral Agent shall not have any
duty to disclose, and shall not be liable for the failure to disclose, any
information relating to any Credit Party or any of their respective
subsidiaries that is communicated to or obtained by The Chase Manhattan Bank or
any of its Affiliates in any capacity.  The Collateral Agent shall not be
liable for any action taken or not taken by it with the consent or at the
request of the Required Secured Parties, or in the absence of its own gross
negligence or wilful misconduct.  The Collateral Agent shall not be deemed to
have knowledge of any Default unless and until written notice thereof is given
to the Collateral Agent by the Borrower, a Secured Party or the Administrative
Agent, and the Collateral Agent shall not be responsible for or have any duty
to ascertain or inquire into (i) any statement, warranty or representation made
in or in connection with this Agreement or the other Security Documents, (ii)
the contents of any certificate, report or other document delivered hereunder
or under any of the other Security Documents or in connection herewith of
therewith, (iii) the performance or observance of any of the covenants,
agreements or other terms or conditions set forth herein or in any other
Security Document, (iv) the





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<PAGE>   54
                                     - 8 -



validity, enforceability, effectiveness or genuineness of this Agreement, the
other Security Documents or any other agreement, instrument or document, or (v)
the satisfaction of any condition set forth in Article V of the respective Loan
Agreements or the Second Secured Vendor Financing Agreement.

                 The Collateral Agent shall not, except to the extent expressly
instructed by the Required Secured Parties with respect to collateral security
under the Security Documents, be required to initiate or conduct any litigation
or collection proceedings hereunder, under any Second Secured Loan Document.

                 The Collateral Agent shall be entitled to rely upon, and shall
not incur any liability for relying upon, any notice, request, certificate,
consent, statement, instrument, document or other writing believed by it to be
genuine and to have been signed or sent by the proper Person.  The Collateral
Agent also may rely upon any statement made to it orally or by telephone and
believed by it to be made by the proper Person, and shall not incur any
liability for relying thereon.  The Collateral Agent may consult with legal
counsel (who may be counsel for the Borrower), independent accountants and
other experts selected by it, and shall not be liable for any action taken or
not taken by it in accordance with the advice of any such counsel, accountants
or experts.

                 The Collateral Agent may perform any and all of its duties,
and exercise its rights and powers, by or through any one or more sub-agents
appointed by the Collateral Agent.  The Collateral Agent and any such sub-agent
may perform any and all of its duties and exercise its rights and powers
through their respective Related Parties.  The exculpatory provisions of the
preceding paragraphs shall apply to any such sub-agent and to the Related
Parties of the Collateral Agent and any such sub-agent, and shall apply to
their respective activities in connection with the syndication of the credit
facilities provided for in the Credit Agreement as well as activities as the
Collateral Agent.

                 Subject to the appointment and acceptance of a successor
Collateral Agent as provided in this paragraph, the Collateral Agent may resign
at any time by notifying the Secured Parties, the Borrower and the
Administrative Agent.  Upon any such resignation, the Required Secured Parties
shall have the right, in consultation with the Borrower, to appoint, in
consultation with the Borrower, a successor Collateral Agent.  If no successor
shall have been so appointed and shall have accepted such appointment within 30
days after such retiring Collateral Agent gives notice of its resignation, then
such retiring Collateral Agent may, on behalf of the Secured Parties, appoint a
successor Collateral Agent, which shall be a bank with an office in New York,
New York, or an Affiliate of any such bank.  Upon the acceptance of its
appointment as Collateral Agent by a successor, such successor shall succeed to
and become vested with all the rights, powers, privileges and duties of the
retiring





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   55
                                     - 9 -



Collateral Agent, and the retiring Collateral Agent shall be discharged from
its duties and obligations hereunder and under the other Security Documents.
The fees payable by the Borrower to a successor Collateral Agent shall be the
same as those payable to its predecessor unless otherwise agreed between the
Borrower and such successor.  After a Collateral Agent's resignation hereunder,
the provisions of this Article and Section 7.03 of the Restricted Company
Guarantee and Security Agreement shall continue in effect for its benefit in
respect of any actions taken or omitted to be taken by it while it was acting
as Collateral Agent.

                 Each Vendor Lender acknowledges that it has, independently and
without reliance upon the Collateral Agent, or any other Secured Party and
based on such documents and information as it has deemed appropriate, made its
own credit analysis and decision to enter into the Second Secured Vendor
Financing Agreement.  Each Vendor Lender also acknowledges that it will,
independently and without reliance upon the Collateral Agent or any other
Secured Party and based on such documents and information as it shall from time
to time deem appropriate, continue to make its own decisions in taking or not
taking action under or based upon this Agreement and the other Security
Documents, any related agreement or any document furnished hereunder or
thereunder.


                                  ARTICLE III

                            Intentionally Left Blank

                 This Article III has been intentionally left blank.


                                   ARTICLE IV

                               Priority of Liens

                 It is the intent of the parties hereto that the Liens created
pursuant to the Security Documents in favor of the Collateral Agent, insofar as
the same shall secure the Second Secured Obligations, shall be second in
ranking to the Liens created pursuant to the Security Documents in favor of the
Collateral Agent, insofar as the same shall secure the Senior Secured
Obligations.  Accordingly, anything in any of the Second Secured Loan
Documents, or any other agreement or instrument between any of the Restricted
Companies and any of the Secured Parties to the contrary notwithstanding:





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   56
                                     - 10 -



                 (a)  Each Vendor Lender, in its capacity as a Vendor Lender
         under the Second Secured Vendor Financing Agreement and solely with
         reference thereto, hereby assigns to the Collateral Agent any Liens
         upon any property of any of the Restricted Companies that it may now
         hold or which may hereafter arise by operation of law or otherwise
         (excluding, however, any such Lien arising pursuant to the Security
         Documents); and

                 (b)  Each Vendor Lender hereby agrees with the Collateral
         Agent for the benefit of the Collateral Agent and the "Lenders" and
         the "Vendors" under the Loan Agreements that the only Liens securing
         obligations of any of the Restricted Companies to the Vendor Lenders
         under the Second Secured Loan Documents shall be the Liens arising
         under the Security Documents, and that the obligations of the
         Restricted Companies under the Vendor Equipment Agreements shall not
         be entitled to the benefits of any Liens; and

Notwithstanding the foregoing, it is understood that none of the Vendor Lenders
is waiving, renouncing or sharing the benefit of any rights of reclamation or
other remedies accorded a manufacturer, supplier or distributor it may have
under State law, common law or otherwise arising out of the sale of equipment
or other goods by such Vendor Lender to the Restricted Companies.

                 Each Vendor Lender hereby agrees that, to the extent such
Vendor Lender is a party to either of the Loan Agreements, that such Vendor
Lender will exercise any right of set-off or counterclaim first with respect to
the obligations of the Restricted Companies under such Loan Agreement (the
proceeds of which exercise shall therefor be subject to the provisions of
Section 2.16(d) of such Loan Agreement) before exercising any such right with
respect to the obligations of the Restricted Companies under the Second Secured
Vendor Financing Agreement.

                 It is the intent of the parties hereto that the Vendor Lenders
shall not have any right to require the Collateral Agent to exercise any of the
rights and remedies available to it with respect to the Second Secured
Obligations until after the Senior Termination Date, or to refrain from the
exercise of any of the rights and remedies available to it with respect to the
Senior Secured Obligations prior to the Senior Termination Date and not to (A)
oppose any request for relief with respect to the Collateral during the
pendency of any bankruptcy or insolvency proceeding and (B) request any relief
with respect to the Collateral during the pendency of any such proceeding
without the prior consent of the Required Secured Parties.  Without limiting
the generality of the foregoing, if any of the Restricted Companies shall
become subject to a proceeding under the United States Bankruptcy Code and if
as debtor(s)-in-possession move for approval of financing to be provided in
good faith by the Lenders or





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   57
                                     - 11 -



Vendors under Section 364 of the United States Bankruptcy Code, or the use of
cash collateral with the consent of the Lenders or Vendors under Section 363 of
the United States Bankruptcy Code, each of the Vendor Lenders hereby agrees
that as follows:

                          (i)  adequate notice by the Lenders and Vendors shall
         have been provided for such financing or use of cash collateral if the
         Vendor Lenders receive notice three (3) business days prior to the
         entry of the order approving (and at least one (1) business day prior
         to the hearing on) such financing or use of cash collateral and

                          (ii)  no objection will be raised by the Vendor
         Lenders to any such financing on the grounds of a failure to provide
         "adequate protection" for the Liens of the Collateral Agent insofar as
         securing the Second Secured Obligations or as a result of any of the
         terms of such financing so long as (A) the interest rate, fees,
         advance rates, lending sublimits and limits and other terms are
         commercially reasonable under the circumstances and (B) the Collateral
         Agent retains a Lien on the Collateral for the benefit of the Second
         Secured Obligations (including proceeds thereof arising after the
         commencement of such proceeding) with the same priority as existed
         prior to the commencement of the proceeding under the United States
         Bankruptcy Code.

                 Notwithstanding the preceding paragraph, the provisions of
clauses (i) and (ii) above shall not be applicable to (a) Motorola or (b) any
Vendor Lender who is simultaneously either a "Lender" under the Credit
Agreement or a "Vendor" under the Vendor Financing Agreement so long as such
Vendor Lender continues to be a "Lender" or a "Vendor" under such Loan
Agreements, and provided further that any Loans held by such Vendor Lender
pursuant to the Loan Agreements shall have been held for at least 180 days
prior to the commencement of any bankruptcy or insolvency proceeding.  Nothing
in the preceding sentence is intended to override the provisions of the
Security Documents that at least 51% or all, as the case may be, of the Vendor
Lenders are necessary to require the Collateral Agent to take or refrain from
taking any action under the Security Documents.  Nothing contained herein shall
be deemed to limit the rights of any Vendor Lender to object to post-petition
financing or use of cash collateral not covered by the preceding paragraph.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   58
                                     - 12 -



                                   ARTICLE V

                                 Miscellaneous

                 SECTION 5.01.  Notices.  All notices and other communications
provided for herein shall be in writing and shall be delivered by hand or
overnight courier service, mailed by certified or registered mail or sent by
telecopy, as follows:

                 (a)  if to the Borrower, to it at 1505 Farm Credit Drive,
         Suite 100, McLean, Virginia 22102, Attention Steven Shindler, Senior
         Vice President and Chief Financial Officer (Telecopy No.
         703-394-3011);

                 (b)  if to any Restricted Company other than the Borrower, to
         such Restricted Company care of the Borrower at the address for
         notices indicated in clause (a) above;

                 (c)  if to Motorola, to it at 1301 East Algonquin Road,
         Schaumburg, Illinois 60196, Attention Vice President, Director of
         Financing (Telecopy No. 847-538-2491), with a copy to Gary Tatje at
         such address and to the General Counsel and Secretary at 1303 East
         Algonquin Road, Schaumburg, Illinois 60196;

                 (d)  if to any Vendor Lender other than Motorola, to it at
         such address as shall be specified by such Vendor Lender at the time
         such Vendor Lender is deemed to become a party hereto as contemplated
         in Section 5.04 hereof; and

                 (e)  if to the Collateral Agent, to it at 270 Park Avenue,
         37th Floor, New York, New York 10017, Attention Tracey Navin,
         (Telecopy No. 212-270-4164).

Any party hereto may change its address or telecopy number for notices and
other communications hereunder by notice to the other parties hereto.  All
notices and other communications given to any party hereto in accordance with
the provisions of this Agreement shall be deemed to have been given on the date
of receipt.

                 SECTION 5.02.  Waivers; Amendments.

                 (a)  No failure or delay by the Collateral Agent or any
Secured Party in exercising any right or power hereunder shall operate as a
waiver thereof, nor shall any single or partial exercise of any such right or
power, or any abandonment or discontinuance of steps to enforce such a right or
power, preclude any other or further exercise thereof or the exercise of any
other right or power.  The rights and remedies of the Collateral Agent





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   59
                                     - 13 -



and the Secured Parties hereunder are cumulative and are not exclusive of any
rights or remedies that they would otherwise have.  No waiver of any provision
of this Agreement or consent to any departure by any party therefrom shall in
any event be effective unless the same shall be permitted by paragraph (b) of
this Section 5.02, and then such waiver or consent shall be effective only in
the specific instance and for the purpose for which given.

                 (b)  Neither this Agreement nor any provision hereof may be
waived, amended or modified except pursuant to an agreement or agreements in
writing entered into by the Restricted Companies, the Required Vendor Lenders
and the Collateral Agent.

                 (c)  No Security Document (other than this Agreement, as to
which paragraph (b) above shall control) nor any provision thereof may be
waived, amended or modified except pursuant to an agreement or agreements in
writing entered into by the Restricted Companies party thereto, and by the
Collateral Agent with the consent of the Required Secured Parties; provided
that, (i) without the written consent of each Secured Party, no such agreement
shall release any Restricted Company from its obligations under any Security
Document and (ii) without the written consent of each Secured Party, no such
agreement shall release any collateral or otherwise terminate any Lien under
any Security Document, agree to additional obligations being secured by such
collateral security (unless either (x) the Lien for such additional obligations
shall be junior to the Lien in favor of the Second Secured Obligations secured
by such Security Document, in which event the Collateral Agent may consent to
such junior Lien provided that it obtains the consent of the Required Secured
Parties thereto or (y) such additional obligations arise as a result of the
incurrence of the "Additional Vendor Loans" (as defined in the Second Secured
Vendor Financing Agreement), in which event the Collateral Agent may consent to
such additional obligations being secured by such collateral, without the
consent of the Vendor Lenders under the Second Secured Vendor Financing
Agreement), alter the relative priorities of the obligations entitled to the
benefits of the Liens created under the Security Documents or release any
Guarantor under the Restricted Company Guarantee and Security Agreement from
its guarantee obligations thereunder, except that no such consent shall be
required, and the Collateral Agent is hereby authorized, to release any Lien
covering property (and to release any such Guarantor) that is the subject of
either a disposition of property permitted under the Loan Agreements and the
Second Secured Vendor Financing Agreement or a disposition to which the
"Required Lenders", "Required Vendors" and "Required Vendor Lenders" under the
Loan Agreements and the Second Secured Vendor Financing Agreement have
consented; provided further that no such agreement shall amend, modify or
otherwise affect the rights or duties of the Collateral Agent without the prior
written consent of the Collateral Agent.

                 SECTION 5.03.  Indemnification.  To the extent that the Credit
Parties fail to pay any amount required to be paid by them to the Collateral
Agent under Section 7.03(a) of the Restricted Company Guarantee and Security
Agreement that arises after the Senior Termination Date, each Vendor Lender
severally agrees to pay to the Collateral Agent such Vendor Lender's Applicable
Percentage (determined as of the time that the applicable unreimbursed expense
or indemnity payment is sought) of such unpaid amount; provided that





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   60
                                     - 14 -



the unreimbursed expense or indemnified loss, claim, damage, liability or
related expense, as the case may be, was incurred by or asserted against the
Collateral Agent in its capacity as such.

                 SECTION 5.04.  Successors and Assigns.  The provisions of this
Agreement shall be binding upon and inure to the benefit of the respective
successors and assigns of the Restricted Companies, the Collateral Agent, the
Secured Parties and each holder of the Secured Obligations.  Nothing in this
Agreement, expressed or implied, shall be construed to confer upon any Person
(other than the parties hereto, the Secured Parties and the respective
successors and assigns of the Restricted Companies, the Collateral Agent, the
Secured Parties and each holder of the Secured Obligations) any legal or
equitable right, remedy or claim under or by reason of this Agreement.

                 As provided in Section 10.04(b) of the Second Secured Vendor
Financing Agreement, upon any assignment by any Vendor Lender of any interest
in the "Tranche D Loans" or "Tranche D Commitment" under the Second Secured
Vendor Financing Agreement held by it, the respective assignee shall be deemed
to have become a party to this Agreement (and thereby to have consented to be
bound by, and subject to the provisions of, this Agreement).

                 SECTION 5.05.  Counterparts.  This Agreement may be executed
in counterparts (and by the parties hereto on different counterparts), each of
which shall constitute an original, but all of which when taken together shall
constitute a single contract.

                 SECTION 5.06.  Severability.  Any provision of this Agreement
held to be invalid, illegal or unenforceable in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such invalidity, illegality
or unenforceability without affecting the validity, legality and enforceability
of the remaining provisions hereof; and the invalidity of a particular
provision in a particular jurisdiction shall not invalidate such provision in
any other jurisdiction.

                 SECTION 5.07.  Governing Law.  This Agreement shall be
construed in accordance with and governed by the law of the State of New York.

                 SECTION 5.08.  Headings.  Article and Section headings used
herein are for convenience of reference only, are not part of this Agreement
and shall not affect the construction of, or be taken into consideration in
interpreting, this Agreement.





          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   61
                                     - 15 -



                 IN WITNESS WHEREOF, the parties hereto have caused this Second
Secured Intercreditor and Collateral Agency Agreement to be duly executed by
their respective authorized officers as of the day and year first above
written.


                           RESTRICTED COMPANIES

                                NEXTEL FINANCE COMPANY (successor to
                                  Fleet Call Corporation),

                                   By
                                                                        
                                         -------------------------------
                                         Name:
                                         Title:

                                ADVANCED MOBILECOMM OF
                                  NORTH CAROLINA, INC.
                                AIRLINK COMMUNICATIONS, INC.
                                  (successor to TRS, Inc.)
                                AMERICAN MOBILE SYSTEMS,
                                  INCORPORATED (successor to Saber
                                  Communications, Inc.)
                                DIAL CALL, INC.
                                DIAL DISTANCE, INC.
                                FC NEW YORK, INC. (successor to Metrocom
                                  Trunked Radio Communication Systems, Inc.)
                                FCI 900, INC.
                                FLEET CALL OF TEXAS, INC. (successor to
                                  FM Tower Company, Metrolink
                                  Communications Corporation and National
                                  Tower Trunking Systems, Inc.)
                                NEXTEL COMMUNICATIONS OF THE
                                  MID-ATLANTIC, INC. (successor to Dispatch
                                  Communications of Maryland, Inc., Dispatch
                                  Communications of Minnesota, Inc., Dispatch
                                  Communications of New England, Inc.,
                                  Dispatch Communications of Pennsylvania,Inc.)
                                NEXTEL LICENSE HOLDINGS 1, INC.
                                NEXTEL LICENSE HOLDINGS 2, INC.
                                  (successor to Comqor, Inc.)






          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   62
                                     - 16 -



                   NEXTEL LICENSE HOLDINGS 3, INC.
                     (successor to Dial Call Arkansas, Inc.,
                     Custom Radio/Johnson Communications, Inc.,
                     Dial Call Florida, Inc., Dial Call
                     Kentucky, Inc., Dial Call Louisiana, Inc.,
                     Dial Call Texas, Inc., Dial Call
                     Virginia, Inc., Dial Call West Virginia, Inc.
                     and U.S. Digital, Inc.)
                   NEXTEL LICENSE HOLDINGS 4, INC.
                   NEXTEL OF TEXAS, INC. (successor to Fort
                     Worth Communications, Inc.)
                   NEXTEL WEST CORP.
                     (successor to Airwave Communications Corp.
                     (Seattle), C-Call Corporation, Dispatch
                     Communications of Arizona, Inc., ESMR Sub,
                     Inc., Fleet Call of Utah, Inc., Fleet Call
                     West, Inc., Mijac Enterprises, Inc., Mobile
                     Radio of Illinois, Inc., Motorola SF, Inc.,
                     Nextel Hawaii Acquisition Corp.,
                     Nextel Utah Acquisition Corp., Nextel
                     Western Acquisition Corp., OneComm
                   Corporation, N.A., Powerfone
                     Holdings, Inc., Powerfone, Inc.,
                     Smart SMR of Illinois, Inc., Shoreland
                     Communications, Inc. and Spectrum Resources
                     of the Midwest, Inc.)
                   SAFETY NET, INC.
                   SMART SMR, INC.
                   SMART SMR OF CALIFORNIA, INC.
                   SMART SMR OF NEW YORK, INC.

                    By
                                                 
                            -------------------------------
                            Name:
                            Title:






          Second Secured Intercreditor and Collateral Agency Agreement
<PAGE>   63
                                     - 17 -



                             FORT WORTH TRUNKED RADIO
                               LIMITED PARTNERSHIP

                             By Nextel of Texas,
                                a General Partner


                                By
                                                                     
                                      -------------------------------
                                      Name:
                                      Title:


                        MOTOROLA
                        --------

                       MOTOROLA, INC.

                          By
                                                                     
                                 ------------------------------------
                                 Name:
                                 Title:

                    COLLATERAL AGENT
                    ----------------

                       THE CHASE MANHATTAN BANK, as
                         Collateral Agent

                          By
                                                                     
                                 ------------------------------------
                                 Name:
                                 Title:






          Second Secured Intercreditor and Collateral Agency Agreement

<PAGE>   1
                                                               [Execution Copy]


                 AMENDMENT NO. 3 TO VENDOR FINANCING AGREEMENT


                  AMENDMENT NO. 3 TO VENDOR FINANCING AGREEMENT dated as of
August 29, 1997 between NEXTEL COMMUNICATIONS, INC. ("NCI"); NEXTEL FINANCE
COMPANY (the "Borrower") and the other Restricted Companies listed on the
signature pages hereto under the caption "RESTRICTED COMPANIES" (individually,
a "Restricted Company" and, collectively, the "Restricted Companies");
MOTOROLA, INC. ("Motorola"); and NTFC CAPITAL CORPORATION ("NTFC Capital" and,
together with Motorola, the "Vendors").

                  NCI, the Restricted Companies and the Vendors are parties to
an Amended, Restated and Consolidated Credit Agreement dated as of September
27, 1996 (as modified and supplemented and in effect from time to time, the
"Vendor Financing Agreement"), providing, subject to the terms and conditions
thereof, for loans to be made by Motorola and NTFC Capital to the Borrower in
an aggregate principal or face amount not exceeding $345,000,000. NCI, the
Restricted Companies and the Vendors wish to increase the "Tranche A
Commitment" of Motorola under the Vendor Financing Agreement by $50,000,000 and
to consent to the amendment of the Vendor Financing Agreement in certain other
respects, and accordingly, the parties hereto hereby agree as follows:

                  Section 1. Definitions. Except as otherwise defined in this
Amendment No. 3, terms defined in the Vendor Financing Agreement are used
herein as defined therein.

                  Section 2. Intentionally Left Blank. This Section 2 has been
intentionally left blank.

                  Section 3. Amendments. Subject to the satisfaction of the
conditions precedent specified in Section 6 below, but effective as of the date
hereof, the Vendor Financing Agreement shall be amended as follows:

                  3.01 References Generally. References in the Vendor Financing
Agreement (including references to the Vendor Financing Agreement as amended
hereby) to "this Agreement" (and indirect references such as "hereunder",
"hereby", "herein" and "hereof") shall be deemed to be references to the Vendor
Financing Agreement as amended hereby.

                  3.02 Definitions. Section 1.01 of the Vendor Financing
Agreement is hereby amended by adding the following new definitions (to the
extent not already included in said Section 1.01) and inserting the same in the
appropriate alphabetical locations and amending the following definitions (to
the extent already included in said Section 1.01), as follows:



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   2

                                     - 2 -


                     (i)  Amendment No. 3:  a definition of "Amendment No. 
         3" is hereby inserted as follows:

                      "Amendment No. 3" means Amendment No. 3 to this Agreement.

                    (ii)  Amendment No. 3 Effective Date:  a definition of 
         "Amendment No. 3 Effective Date" is hereby inserted as follows:

                      "Amendment No. 3 Effective Date" means the date on which
                  the conditions to the effectiveness of the amendments 
                  provided for in Amendment No. 3 set forth in Section 6 
                  thereof are satisfied (or waived in accordance with said 
                  Section 6).

                   (iii)  Permitted Debt Limitation: the definition of
         "Permitted Debt Limitation" shall be amended to read in its entirety
         as follows:

                      "Permitted Debt Limitation" means, at any date, the
                  amount of Indebtedness permitted to be incurred on such date
                  (a) pursuant to clause (iii) of the definition of "Permitted
                  Debt" under each of the Public Note Indentures.

                    (iv)  Required Parties:  a definition of "Required
         Parties" is hereby inserted as follows:

                      "Required Parties" means, at any time, Vendors and
                  Vendor Lenders having Loans hereunder and "Tranche D Loans"
                  under the Second Secured Vendor Financing Agreement, and
                  unused Commitments hereunder and "Tranche D Commitments"
                  under the Second Secured Vendor Financing Agreement,
                  representing at least 51% of the sum of the total Loans and
                  such "Tranche D Loans" and unused Commitments and such
                  "Tranche D Commitments" at such time.

                     (v)  Second Secured Intercreditor and Collateral Agency
         Agreement: a definition of "Second Secured Intercreditor and
         Collateral Agency Agreement" is hereby inserted as follows:

                      "Second Secured Intercreditor and Collateral Agency
                  Agreement" means a Second Secured Intercreditor and
                  Collateral Agency Agreement substantially in the form of
                  Exhibit B to Amendment No. 3 hereto (or such other form as
                  may be approved by the Required Vendors, NCI and the
                  Collateral Agent) among NCI, the Restricted Companies, the
                  Vendor Lenders party thereto and the Collateral Agent.


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   3

                                     - 3 -


                        (vi) Second Secured Vendor Financing Agreement: a
         definition of "Second Secured Vendor Financing Agreement" is hereby
         inserted as follows:

                           "Second Secured Vendor Financing Agreement" means a
                  Second Secured Vendor Financing Agreement, substantially in
                  the form of the draft thereof dated August 22, 1997,
                  previously delivered to each of the Vendors (or such other
                  form as may be approved by the Required Vendors), among NCI,
                  the Restricted Companies and the Vendor Lenders referred to
                  therein.

                       (vii) Tranche A Commitment: the definition of "Tranche A
         Commitment" shall be amended to read in its entirety as follows:

                           "Tranche A Commitment" means the commitment of
                  Motorola to make Tranche A Loans hereunder (a portion of
                  which commitment may be allocated by Motorola to Lehman
                  Commercial Paper, Inc. ("LCPI"), under separate arrangements
                  to be entered into between Motorola and LCPI). The amount of
                  the Tranche A Commitment (after giving effect to the
                  reallocation of $60,000,000 to Tranche C Loans as
                  contemplated by Section 2.01(d) that has occurred prior to
                  the Amendment No. 3 Effective Date, and to Amendment No. 3
                  hereto) is $100,000,000.

                      (viii) Tranche C Commitment: the definition of "Tranche C
         Commitment" shall be amended to read in its entirety as follows:

                           "Tranche C Commitment" means the commitment of NTFC
                  Capital to make Tranche C Loans hereunder. The amount of the
                  Tranche C Commitment (after giving effect to the reallocation
                  of $60,000,000 of Tranche A Loans as contemplated by Section
                  2.01(d) that has occurred prior to the Amendment No. 3
                  Effective Date) is $100,000,000.

                        (ix)  Vendor Lenders:  a definition of "Vendor Lenders"
         is hereby inserted as follows:

                           "Vendor Lenders" means the "Vendor Lenders" from
                  time to time party to the Second Secured Vendor Financing
                  Agreement.


                  3.03 Commitments. Paragraph (a) of Section 2.01 of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "(a)  Tranche A Loans.  Subject to the terms and conditions
         set forth herein, Motorola agrees to make Tranche A Loans to the
         Borrower on the Effective Date in a


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   4


                                     - 4 -


         principal amount equal to the Tranche A Commitment as in effect on the
         Effective Date, and to make additional Tranche A Loans on a single
         date on or after the Amendment No. 3 Effective Date (but not in any
         event later than March 31, 1999) in a principal amount equal to the
         unused portion of the Tranche A Commitment as increased pursuant to
         Amendment No. 3 hereto (and after giving effect to the reallocation of
         Tranche A Loans to Tranche C Loans as contemplated by Section
         2.01(d)), provided that on the Effective Date a portion of the
         Existing Vendor Indebtedness held by Motorola (before giving effect to
         the designation provided for in paragraph (b) of this Section 2.01) up
         to but not exceeding the Tranche A Commitment shall be automatically
         designated as Tranche A Loans hereunder."

                  3.04 Requests for Borrowing. Clause (i) of Section 2.03 of
the Vendor Financing Agreement is hereby amended to read in its entirety as
follows:

                  "(i) in the case of a Borrowing from Motorola on the
         Effective Date or on a single date on or after the Amendment No. 3
         Effective Date (as contemplated by Section 2.01(a)), whether such
         Borrowing is to be a Tranche A Borrowing or Tranche B Borrowing;"

                  3.05 Termination of Commitments. Section 2.07(a) of the
Vendor Financing Agreement is hereby amended to read in its entirety as
follows:

                  "(a) Unless previously terminated, (i) the Tranche A
         Commitment shall terminate after the Borrowing of Tranche A Loans that
         utilizes the increase in Tranche A Commitment pursuant to Amendment
         No. 3, (ii) the Tranche B Commitment shall terminate at the close of
         business on the Maturity Date and (iii) the Tranche C Commitment shall
         terminate after the Borrowing of Tranche C Loans on the Effective
         Date."

                  3.06 Repayment of Loans. Paragraphs (b) and (c) of Section
2.08 of the Vendor Financing Agreement are hereby to read in their entireties
as follows:



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   5


                                     - 5 -


                  "(b) The Borrower hereby unconditionally promises to pay the
         principal of the Tranche A Loans in nine installments payable on the
         Principal Payment Dates as follows (the amounts set forth below being
         determined after giving effect to the reallocation of $60,000,000 of
         Tranche A Loans to Tranche C Loans as contemplated by Section 2.01(d),
         and to the increase of the Tranche A Commitments contemplated by
         Amendment No. 3 hereto):

<TABLE>
<CAPTION>
           Principal Payment Date
         Falling on or Nearest to:                Amount of Installment
         -------------------------                ---------------------
         <S>                                      <C>
             March 31, 2001                             $3,750,000
             June 30, 2001                              $3,750,000
             September 30, 2001                         $3,750,000
             December 31, 2001                          $3,750,000

             March 31, 2002                             $5,000,000
             June 30, 2002                              $5,000,000
             September 30, 2002                         $5,000,000
             December 31, 2002                          $5,000,000

             March 31, 2003                             $65,000,000
</TABLE>

                  (c) The Borrower hereby unconditionally promises to pay the
         principal of the Tranche C Loans in nine installments payable on the
         Principal Payment Dates as follows (the amounts set forth below being
         determined after giving effect to the reallocation of $60,000,000 of
         Tranche A Loans to Tranche C Loans as contemplated by Section
         2.01(d)):

<TABLE>
<CAPTION>
           Principal Payment Date
         Falling on or Nearest to:                Amount of Installment
         -------------------------                ---------------------
         <S>                                      <C>
             March 31, 2001                              $7,500,000
             June 30, 2001                               $7,500,000
             September 30, 2001                          $7,500,000
             December 31, 2001                           $7,500,000

             March 31, 2002                              $10,000,000
             June 30, 2002                               $10,000,000
             September 30, 2002                          $10,000,000
             December 31, 2002                           $10,000,000

             March 31, 2003                             $30,000,000"
</TABLE>


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   6


                                     - 6 -



                  3.07 Certain Mandatory Prepayments. The first paragraph of
Section 2.09(b)(ii) of the Vendor Financing Agreement (i.e. prior to the
beginning of clause (w) thereof) is hereby amended to read in its entirety as
follows:

                       "(ii) Sale of Assets. Without limiting the obligation of
         the Restricted Companies to obtain the consent of the Required Vendors
         to any Disposition not otherwise permitted hereunder, the Borrower
         agrees, on or prior to the occurrence of any Disposition (herein, the
         "Current Disposition") as to which the estimated amount of the Net
         Cash Payments, together with all prior Dispositions as to which a
         prepayment has not yet been made under this Section 2.09(b)(ii) and as
         to which a report contemplated by this Section 2.09(b)(ii) has not
         been delivered, shall exceed $5,000,000, to deliver to the Vendors a
         report certified by a Financial Officer, in form and detail reasonably
         satisfactory to the Required Vendors, with respect to such Current
         Disposition and all such prior Dispositions setting out the estimated
         amount of the Net Cash Payments of all such Dispositions that will (on
         the date of the Current Disposition) have been received in cash
         whereupon the Borrower will prepay the Loans hereunder and under the
         Credit Agreement (and provide cover for LC Exposure as specified in
         clause (iv) of Section 2.09(b) of the Credit Agreement), and the
         Commitments hereunder and under the Credit Agreement shall be subject
         to automatic reduction, as follows:"

                  3.08 Interest. Clause (iii) of Section 2.11(c) of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "(iii)  this clause (iii) has been intentionally left blank,"

                  3.09 Public Note Indentures. Section 4.17 of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "SECTION 4.17.  Public Note Indentures.  NCI has heretofore
         delivered to each Vendor a true and complete copy of each Public Note
         Indenture (including all modifications and supplements thereto).  The
         Restricted Companies constitute all of the "Restricted Subsidiaries"
         on the date hereof under and as defined in the Public Note Indentures."

                  3.10 Conditions to Each Loan. Section 5.02 of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "SECTION 5.02.  Each Loan.  The obligation of each Vendor to
         make a Loan on the occasion of any Borrowing is subject to the
         satisfaction of the following conditions:



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   7


                                     - 7 -


                           (a) Representations and Warranties. The
                  representations and warranties of each Credit Party set forth
                  in this Agreement and the other Loan Documents shall be true
                  and correct on and as of the date of such Borrowing both
                  before and after giving effect thereto and to the use of the
                  proceeds thereof (or, if any such representation or warranty
                  is expressly stated to have been made as of a specific date,
                  such representation or warranty shall be true and correct as
                  of such specific date).

                           (b) No Defaults. At the time of and immediately
                  after giving effect to such Borrowing no Default shall have
                  occurred and be continuing.

                           (c) Public Note Indenture Compliance. The Borrower
                  shall have delivered to the respective Vendor a certificate
                  of a Financial Officer demonstrating that one of the
                  following shall be true: (i) after giving effect to such
                  Borrowing, the aggregate amount of all outstanding Loans
                  hereunder, and Indebtedness under the Second Secured Vendor
                  Financing Agreement, and any other Indebtedness of NCI and
                  its subsidiaries that utilizes the exceptions referred to in
                  the definition of "Permitted Debt Limitation" in Section
                  1.01, will not exceed the Permitted Debt Limitation or (ii)
                  such Borrowing is permitted to be incurred on such date under
                  Section 1008 of each Public Note Indenture (other than the
                  January 1994 Indenture), under Section 10.8 of the January
                  1994 Indenture.

                           (d) Secured Indebtedness to Revenue Ratio. After
                  giving effect to such Borrowing, the Secured Indebtedness to
                  Revenue Ratio shall not exceed the applicable amount set
                  forth in Section 7.08(f).

         Each Borrowing Request shall be deemed to constitute a representation
         and warranty by the Borrower (both as of the date of such Borrowing
         Request and as of the date of the related Borrowing as to the matters
         specified in paragraphs (a), (b) and (d) of this Section 5.02.

                  3.11 Financial Statements. Paragraph (d) of Section 6.01 of
the Vendor Financing Agreement are hereby amended to read in its entirety as
follows:

                  "(d) concurrently with any delivery of financial statements
         under clause (a), (b) or (c) above, a certificate of a Financial
         Officer of each of NCI and the Borrower (i) certifying as to whether a
         Default has occurred and, if a Default has occurred, specifying the
         details thereof and any action taken or proposed to be taken with
         respect thereto, (ii) setting forth reasonably detailed calculations
         demonstrating compliance with Sections 7.01(d), 7.01(g), 7.03(f),
         clauses (iv) through (viii) of 7.04(a), 7.05(c) and 7.08 (which
         calculations shall include the corresponding figures


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   8


                                     - 8 -


         for the most-recently ended fiscal quarter with respect to Capital
         Expenditures and Debt Service necessary to demonstrate compliance with
         said Section 7.08), (iii) setting forth the estimated amount of Net
         Cash Payments received during the most-recently ended fiscal quarter
         from Dispositions during such quarter and (iv) stating whether any
         change in GAAP or in the application thereof has occurred since the
         later of the date of the financial statements as at December 31, 1995
         referred to in Section 4.04 and the date of the last certificate
         delivered pursuant to this clause (d) and, if any such change has
         occurred, specifying the effect of such change on the financial
         statements accompanying such certificate;"

                  3.12 Planned Option Issuances. Section 6.12 of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "SECTION 6.12. Planned Option Issuances. NCI will,
         immediately upon receipt thereof, contribute to one or more of the
         Restricted Companies, as additional equity capital in respect of the
         common stock of the Restricted Companies, any proceeds received by NCI
         after the date hereof from Planned Option Issuances. In addition, NCI
         will from time to time make such contributions of capital to the
         Restricted Companies as shall be necessary so that the aggregate
         amount of Contributed Capital (i) as at July 31, 1997 shall be at
         least equal to $232,000,000, (ii) as at July 31, 1998 shall be at
         least equal to $550,000,000 and (iii) as at December 31, 1999 shall at
         least equal to $1,100,000,000."

                  3.13 Indebtedness. Paragraph (f), (g) and (h) of Section 7.01
of the Vendor Financing Agreement are hereby amended to read in their entirety,
and a new paragraph (i) is inserted in said Section 7.01, as follows:

                  "(f) Indebtedness of the Borrower (and Guarantees thereof by
         the other Restricted Companies pursuant to the Restricted Company
         Guarantee and Security Agreement, and by NCI pursuant to Article III)
         in an aggregate principal amount not exceeding $250,000,000 in respect
         of Tranche E Loans under the Credit Agreement;

                  (g) other Indebtedness (in addition to any amounts permitted
         pursuant to the foregoing paragraphs (a) through (f) and the following
         paragraphs (h) and (i) of this Section 7.01) of the Restricted
         Companies in an aggregate principal amount not exceeding $75,000,000
         at any time outstanding (or such greater amount to which the Required
         Parties shall have consented);

                  (h) other unsecured Indebtedness of NCI in an aggregate
         principal amount not exceeding $10,000,000 at any time outstanding (or
         such greater amount to which the Required Parties shall have
         consented); and



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   9


                                     - 9 -


                  (i) Indebtedness of the Credit Parties under the Second
         Secured Vendor Financing Agreement in an aggregate principal amount
         not exceeding the sum of $200,000,000, plus any amount of additional
         principal resulting from the addition of accrued interest to the
         aggregate principal amount of such Indebtedness pursuant to Section
         2.11(c)(ii) of the Second Secured Vendor Financing Agreement."

                  3.14 Certain Permitted Liens. Clause (a) the second paragraph
of Section 7.02 of the Vendor Financing Agreement is hereby amended to read in
its entirety as follows:

                  "(a) Liens created by the Security Documents securing the
         obligations of the Restricted Companies hereunder, under the Credit
         Agreement and under the Security Documents (in each case subject to
         the provisions of the Intercreditor and Collateral Agency Agreement),
         and under the Second Secured Vendor Financing Agreement (subject to
         the provisions of the Second Secured Intercreditor and Collateral
         Agency Agreement);"

                  3.15 Certain Intercompany Transactions. Clauses (b) and (d)
of the second paragraph of Section 7.03 of the Vendor Financing Agreement are
hereby amended to read in their entirety as follows:

                  "(b) any Restricted Company may merge into any other
         Restricted Company, provided that no such merger may involve a License
         Company, unless (x) immediately after giving effect thereto no Default
         shall have occurred and be continuing and (y) in the case of any
         License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations, the surviving entity in such merger is
         a License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations;

                  (d) any Restricted Company other than the Borrower may sell,
         transfer, lease or otherwise dispose of its assets to another
         Restricted Company, provided that no such transaction may involve a
         disposition of assets of any License Company unless (x) immediately
         after giving effect thereto no Default shall have occurred and be
         continuing and (y) in the case of any transfer of assets by a License
         Company substantially all of whose assets consist of FCC Licenses or
         PUC Authorizations, the acquiror of such assets (after giving effect
         to such acquisition) is a License Company substantially all of whose
         assets consist of FCC Licenses or PUC Authorizations;"

                  3.16 Acquisition Baskets. Clauses (i), (vi), (vii) and (viii)
of Section 7.04(a) of the Vendor Financing Agreement are hereby amended to read
in their entirety as follows:



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   10


                                     - 10 -


                        "(i) Permitted Investments, and Disposition Investments
         received in connection with any Disposition permitted under Section
         7.03(f) or any Disposition to which the Required Vendors shall have
         consented in accordance with Section 10.02, so long as each such
         Disposition Investment shall have been delivered to the Collateral
         Agent to be held as collateral security by the Collateral Agent
         pursuant to the Restricted Company Guarantee and Security Agreement;

                        (vi) acquisitions of SMR Licenses in the
         currently-planned auction of 800 Mhz spectrum by the FCC, so long as:

                           (A) following consummation of each such acquisition,
                  (x) the Restricted Companies shall have complied with the
                  requirements of Section 7.09(b) with respect to the SMR
                  Licenses acquired in such acquisition and (y) all
                  Authorizations required by the FCC in connection with such
                  acquisition shall have been duly granted pursuant to a Final
                  Order and (if the fair market value of the SMR Licenses so
                  acquired shall exceed $10,000,000 and either Vendor shall
                  have requested the same) the Vendors shall have received an
                  opinion of counsel with respect to such acquisition that is
                  satisfactory in form and substance to the Required Vendors;

                           (B) the Borrower shall have delivered to the
                  Administrative Agent a supplement to Schedule 4.13 to the
                  Credit Agreement (and, if requested by either Vendor, shall
                  have delivered a copy thereof to such Vendor) setting forth a
                  list of the respective SMR Licenses acquired in connection
                  with such acquisition; and

                           (C) both immediately prior to each such acquisition
                  and after giving effect thereto, no Default shall have
                  occurred and be continuing;

                       (vii) this clause (vii) has been intentionally left
         blank;

                      (viii) acquisitions of FCC Licenses in the 800 MHz or 900
         MHz band (other than pursuant to the auction referred to in clause
         (vi) above), and acquisitions of any Mobile Communications Business
         and the related assets of any other Person (or, if for the purpose of
         enabling the Restricted Companies to create contiguous blocks of
         spectrum covered by the SMR Licenses of the Restricted Companies,
         acquisitions of cellular telephone and other businesses), whether by
         way of purchase of assets or stock, by merger or consolidation or
         otherwise, so long as:

                           (A) the aggregate Purchase Price for all such
                  acquisitions consummated after the Amendment No. 3 Effective
                  Date (excluding any portion thereof that shall have been paid
                  through the issuance of equity


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   11


                                     - 11 -


                  securities of NCI, and excluding acquisitions pursuant to the
                  terms of one or more definitive agreements as in effect on
                  the Amendment No. 3 Effective Date) shall not exceed
                  $275,000,000;

                           (B) each such acquisition of FCC Licenses is for the
                  purpose of enabling the Restricted Companies to create
                  contiguous blocks of spectrum covered by the SMR Licenses of
                  the Restricted Companies;

                           (C) any such acquisition of a Mobile Communications
                  Business (if by purchase of assets, merger or consolidation)
                  shall be effected in such manner so that the acquired
                  business, and the related assets, are owned by a Restricted
                  Company (which may include a new Wholly Owned Subsidiary that
                  becomes a Restricted Company pursuant to Section 6.11(a))
                  and, if effected by merger or consolidation involving the
                  Borrower, the Borrower shall be the continuing or surviving
                  entity;

                           (D) any such acquisition of a Mobile Communications
                  Business (if by purchase of stock) shall be effected in such
                  manner so that the acquired entity becomes a Wholly Owned
                  Subsidiary that becomes a Restricted Company pursuant to
                  Section 6.11;

                           (E) if the fair market value of the assets of any
                  Mobile Communications Business to be so acquired shall exceed
                  $10,000,000, the Restricted Companies shall deliver to the
                  Vendors (x) no later than five Business Days prior to the
                  consummation of each such acquisition (or such earlier date
                  as shall be five Business Days after the execution and
                  delivery thereof), executed counterparts of the respective
                  agreements or instruments pursuant to which such acquisition
                  is to be consummated (including any related management,
                  non-compete, employment, option or other material
                  agreements), any schedules to such agreements or instruments
                  and all other material ancillary documents to be executed or
                  delivered in connection therewith and (y) promptly following
                  request therefor, copies of such other information or
                  documents relating to each such acquisition as the Required
                  Vendors shall have reasonably requested;

                           (F) following consummation of each such acquisition,
                  (x) the Restricted Companies shall have complied with the
                  requirements of Section 7.09(b) with respect to any FCC
                  Licenses or PUC Authorizations acquired in such acquisition
                  and (y) all Authorizations required by the FCC in connection
                  with such acquisition shall have been duly granted pursuant
                  to a Final Order and (if the fair market value of the assets
                  so acquired shall exceed $10,000,000 and either Vendor shall
                  have requested the same) the Vendors


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   12


                                     - 12 -


                  shall have received an opinion of counsel with respect to
                  such acquisition that is satisfactory in form and substance
                  to the Required Vendors;

                           (G) to the extent applicable, the Restricted
                  Companies shall have complied with the provisions of Section
                  6.11, including delivery to the Collateral Agent of (x) the
                  certificates evidencing any capital stock of a Restricted
                  Company, accompanied by undated stock powers executed in
                  blank and (y) the agreements, instruments, opinions of
                  counsel and other documents required under said Section 6.11
                  to be delivered;

                           (H) in the case of a transaction described in clause
                  (E) above, and upon request by the Required Vendors, the
                  Borrower shall deliver to the Administrative Agent a
                  supplement to Schedule 4.13 to the Credit Agreement (and, if
                  requested by either Vendor, shall have delivered a copy
                  thereof to such Vendor) setting forth a list of the
                  respective SMR Licenses, other FCC Licenses and PUC
                  Authorizations acquired in connection with such acquisition;
                  and

                           (I) both immediately prior to each such acquisition
                  and after giving effect thereto, no Default shall have
                  occurred and be continuing; and"

                  3.17 Restrictive Agreements. Clause (y) of Section 7.07(b)(i)
of the Credit Agreement is hereby amended to read in its entirety as follows:

                           "(y) consisting of customary restrictions on
                  transfers of site leases (provided that, except for leases
                  within the scope of the exceptions contained in Section 6.13
                  of the Restricted Company Guaranty and Security Agreement,
                  the Restricted Companies agree that any such lease entered
                  into after September 27, 1996 shall expressly permit the
                  creation of a security interest in the rights of the
                  respective Restricted Company party thereto as security for
                  indebtedness for borrowed money, or guaranties thereof), or"

                  3.18 Business Activities. Section 7.09(a) of the Vendor
Financing Agreement is hereby amended to read in its entirety as follows:

                  "(a) Business Activities. No Restricted Company will engage
         to any substantial extent in any line or lines of business activity
         other than the Mobile Communications Business, and businesses
         reasonably related thereto, provided that nothing herein shall be
         deemed to prohibit the Restricted Companies from acquisitions pursuant
         to Section 7.04(a)(viii) of FCC Licenses in the 800 MHz or 900 MHz
         bands,


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   13


                                     - 13 -


         or of cellular telephone and other businesses, for the purpose of
         enabling the Restricted Companies to create contiguous blocks of
         spectrum covered by the SMR Licenses of the Restricted Companies."

                  3.19 Modifications to Certain Agreements. The first paragraph
of Section 7.10 of the Vendor Financing Agreement is hereby amended to read in
its entirety as follows:

                  "SECTION 7.10. Modifications to Certain Agreements. The
         Credit Parties will not consent to any modification, supplement or
         waiver of any of the provisions of the Overhead Services Agreement
         (other than to add new Restricted Companies as parties thereto) or the
         Tax Sharing Agreement (other than to add new subsidiaries of NCI as
         parties thereto) or the provisions in Section 2.09 of the Credit
         Agreement relating to the application of prepayments (or the second
         paragraph of Section 2.01(a) thereof), or the provisions of Section
         2.16(d) of the Credit Agreement, without, in each case, the prior
         consent of the Required Vendors. In addition, NCI will not consent to
         any modification, supplement or waiver of any of the provisions of the
         Second Secured Vendor Financing Agreement, the Public Note Indentures
         or the Public Notes without the prior consent of the Required
         Parties."

                  3.20 Certain Events of Default. Clauses (l), (m) and (o) of
Article VIII of the Vendor Financing Agreement are hereby amended to read in
their entirety as follows:

                  "(l) an ERISA Event shall have occurred that, in the opinion
         of the Required Parties, when taken together with all other ERISA
         Events that have occurred, could reasonably be expected to result in a
         Material Adverse Effect;

                  (m) a proceeding shall have been initiated by or before, or
         any action shall have been taken by, the FCC, a PUC, a court of
         competent jurisdiction, or other Governmental Authority which either:

                                  (i) has resulted in the cancellation,
                  non-renewal or adverse modification of any one or more SMR
                  Licenses, radio channels authorized under SMR Licenses or PUC
                  Authorizations held by one or more of the Restricted
                  Companies, or

                                 (ii) in the reasonable opinion of the Required
                  Parties, is likely to result in the cancellation, non-renewal
                  or adverse modification of any one or more SMR Licenses,
                  radio channels authorized under SMR Licenses, or PUC
                  Authorizations held by one or more Restricted Companies,



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   14


                                     - 14 -


         that, in the aggregate, in the judgment of the Required Parties, have
         resulted or are reasonably likely to result in a Material Adverse
         Effect, and the same shall continue uncured for a period of 45 or more
         days after notice thereof to the Borrower by the Required Parties;

                  (o) a reasonable basis shall exist for the assertion against
         any Credit Party, or any predecessor in interest of any Credit Party
         or their Affiliates, of (or there shall have been asserted against any
         Credit Party) any claims or liabilities, whether accrued, absolute or
         contingent, based on or arising from the generation, storage,
         transport, handling or disposal of Hazardous Materials or RF Emissions
         by any Credit Party or any of its subsidiaries, Affiliates or
         predecessors that, in the judgment of the Required Parties is
         reasonably likely to be determined adversely to any Credit Party, and
         the amount thereof (either individually or in the aggregate) is
         reasonably likely to have a Material Adverse Effect (insofar as such
         amount is payable by a Credit Party but after deducting any portion
         thereof that is reasonably expected to be paid by other creditworthy
         Persons jointly and severally liable therefor); or"

                  3.21 Amendments. Section 10.02(b) of the Vendor Financing
Agreement is hereby amended to read in its entirety as follows:

                  "(b) Neither this Agreement nor any provision hereof may be
         waived, amended or modified except pursuant to an agreement or
         agreements in writing entered into by the Restricted Companies and the
         Required Vendors; provided that no such agreement shall:

                                  (i)  increase the Commitment of either Vendor
                  without the written consent of such Vendor;

                                 (ii) reduce the principal amount of any Loan
                  or reduce the rate of interest thereon, or reduce any fees
                  payable hereunder, without the written consent of the Vendor
                  affected thereby;

                                (iii) postpone the scheduled date of payment of
                  the principal amount of any Loan, or any interest thereon, or
                  any fees payable hereunder, or reduce the amount of, waive or
                  excuse any such payment, or postpone the scheduled date of
                  expiration of any Commitment, without the written consent of
                  the Vendor affected thereby;

                                 (iv) this clause (iv) has been intentionally
                  left blank;

                                  (v) alter the rights or obligations of the
                  Borrower to prepay Loans without the written consent of each
                  Vendor (other than the obligations


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   15


                                     - 15 -


                  of the Borrower under Section 2.09(b)(iii), which may be
                  altered with the consent of the Required Vendors);

                                 (vi) change any of the provisions of this
                  Section 10.02 or the definition of "Required Parties",
                  "Required Vendors", or any other provision hereof specifying
                  the number or percentage of Vendors hereunder required to
                  waive, amend or modify any rights hereunder or any other Loan
                  Document or make any determination or grant any consent
                  hereunder or thereunder, without the written consent of each
                  Vendor; or

                                (vii) release NCI from its obligations in
                  respect of its Guarantee under Article III without the
                  written consent of each Vendor."

                  3.22 Certain Restrictions on Assignments. Section 10.04(h) of
the Vendor Financing Agreement is hereby amended to read in its entirety as
follows:

                  "(h) Anything in this Section 10.04 to the contrary
         notwithstanding, (i) no Vendor may assign or participate any interest
         in any Loan held by it hereunder to the Borrower or any of its
         Affiliates or subsidiaries without the prior consent of each Vendor,
         (ii) without the prior consent of the Borrower, Motorola shall (except
         as a result of any assignment or participation made on the basis of
         full recourse to Motorola), at all times either (x) hold Loans
         hereunder, or "Tranche D Loans" under the Second Secured Vendor
         Financing Agreement, in an aggregate principal amount at least equal
         to $50,000,000 (or such lesser amount as shall represent the amount to
         which such $50,000,000 would be reduced ratably in accordance with the
         repayment schedule set forth in Section 2.08(b)) or (y) be obligated
         in respect of the Tranche A Commitment hereunder in an aggregate
         amount at least equal to $50,000,000 (or such lesser amount as shall
         represent the amount to which such $50,000,000 would be reduced
         ratably in accordance with the repayment schedule set forth in Section
         2.08(b)), and for purposes of this paragraph (h), Motorola shall be
         deemed not to hold Loans or Tranche A Commitment hereunder, or
         "Tranche D Loans" under the Second Secured Vendor Financing Agreement,
         if it has either assigned or sold participations in an interest in
         such Loans or Tranche A Commitment, or "Tranche D Loans" as otherwise
         permitted under this Section 10.04 and (iii) NTFC Capital may not
         assign or participate any interest in any Tranche A Loan (other than
         the first $10,000,000 thereof) reallocated to it as Tranche C Loans
         hereunder pursuant to Section 2.01(d) prior to the date six months
         after the Effective Date (other than any such assignment or
         participation made on the basis of full recourse to NTFC Capital)."



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   16


                                     - 16 -


                  3.23 Efforts of Nextel to Locate Assignees. Section 10.04 of
the Vendor Financing Agreement is hereby amended by adding a new paragraph (i)
at the end thereof to read as follows:

                  "(i) NCI agrees with Motorola to use its best efforts in
         assisting Motorola to sell to third parties, on a non-recourse basis,
         a sufficient portion of the exposure to NCI and its Subsidiaries held
         by Motorola for its own account (or guaranteed by Motorola) so that
         the total outstandings so held (or guaranteed) by Motorola hereunder
         and under the Second Secured Vendor Financing Agreement, and in
         respect of any "Tranche E Loans" as contemplated by the Term Sheet
         dated March 26, 1997 between NCI and Motorola, shall not be greater
         than $555,000,000 at any one time."

                  Section 4. Authorization to Amend Restricted Company
Guarantee and Security Agreement. Pursuant to Section 7.02(b) of the Restricted
Company Guarantee and Security Agreement and Section 5.02(c) of the
Intercreditor and Collateral Agency Agreement, each of the Vendors signatory
hereto, and LCPI by its execution and delivery hereof, (a) hereby consents to
the execution and delivery of an Amendment No. 2 to the Restricted Company
Guarantee and Security Agreement in substantially the form attached hereto as
Exhibit A, (b) hereby authorizes the Collateral Agent to enter into the Second
Secured Intercreditor and Collateral Agency Agreement in substantially the form
attached hereto as Exhibit B and (c) hereby consents to the granting of the
Liens with respect to the Collateral to secure the Restricted Companies'
obligations pursuant to the Second Secured Vendor Financing Agreement.

                  Section 5. Representations and Warranties. NCI and each
Restricted Company represents and warrants to the Vendors and LCPI, as to
itself and each of its subsidiaries, that the representations and warranties
set forth in Article IV of the Vendor Financing Agreement are true and complete
on the date hereof (or, if any such representation or warranty is expressly
stated to have been made as of a specific date or as of the date of the Credit
Agreement, such representation or warranty shall be true and correct as of such
specific date or as of September 27, 1996, as applicable) as if made on and as
of the date hereof and as if each reference in said Article IV to "this
Agreement" included reference to this Amendment No. 3 and as if each reference
in said Article IV to "the Transactions" included reference to the execution
and delivery of this Amendment No. 3.

                  Section 6. Conditions Precedent. The amendments set forth in
Section 3 hereof, shall become effective on the date on which each of the
following conditions is satisfied (or waived in accordance with the last
paragraph hereof), and on such date (as provided in Section 2.01(a) of the
Vendor Financing Agreement as amended hereby, Motorola shall have made
additional Tranche A Loans in an amount equal to the increase in the Tranche A
Commitment contemplated hereby):



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   17


                                     - 17 -


                  (a) Counterparts of Amendment. NCI, the Restricted Companies,
         each Vendor and LCPI shall have executed and delivered this Amendment
         No. 3.

                  (b) Opinion of Counsel to Credit Parties. Each Vendor and
         LCPI shall have received a favorable written opinion (addressed to
         such Vendor and LCPI and dated the Amendment No. 3 Effective Date) of
         Jones, Day, Reavis & Pogue, counsel to the Credit Parties, covering
         such matters relating to the Credit Parties, this Amendment No. 3, the
         other Loan Documents or the Transactions as the Required Vendors shall
         request (and each Credit Party hereby requests such counsel to deliver
         such opinion). To the extent deemed appropriate by the Restricted
         Companies, internal corporate matters in such opinion (such as due
         incorporation and the like) may be rendered in a separate opinion from
         the General Counsel of NCI.

                  (c) Corporate Matters. Each Vendor and LCPI shall have
         received such documents and certificates as such Vendor or LCPI may
         reasonably request relating to the organization, existence and good
         standing of each Credit Party, the authorization of this Amendment No.
         3 and any other legal matters relating to the Credit Parties, this
         Amendment No. 3, the other Loan Documents or the Transactions, all in
         form and substance reasonably satisfactory to such Vendor and LCPI and
         their respective counsels.

                  (d) Financial Officer Certificate. Each Vendor and LCPI shall
         have received a certificate, dated the Amendment No. 3 Effective Date
         and signed by the President, a Vice President or a Financial Officer
         of the Borrower, confirming compliance with the conditions set forth
         in paragraphs (a) through (d) of Section 5.02 of the Vendor Financing
         Agreement on the Amendment No. 3 Effective Date after giving effect to
         the Borrowing of Tranche A Loans.

                  (e) Notes. Motorola shall have received a duly completed and
         executed promissory note evidencing the Tranche A Loans made by it
         under the Vendor Financing Agreement, as amended hereby.

                  (f) Credit Agreement Amendment. Each Vendor and LCPI shall
         have received evidence satisfactory in form and substance to it that
         the Restricted Companies, and the Lenders shall have entered into an
         Amendment to the Credit Agreement in substantially the form of the
         draft thereof dated August 22, 1997, previously delivered to each of
         the Vendors.

                  (g) Second Secured Vendor Financing Agreement. Each Vendor
         and LCPI shall have received evidence satisfactory in form and
         substance to it that the Second Secured Vendor Financing Agreement,
         substantially in the form of the draft thereof dated August 22, 1997,
         previously delivered to each of the Vendors, shall have been


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   18


                                     - 18 -


         duly executed and delivered by NCI, the Restricted Companies and
         Vendor Lenders named therein.

                  (h) Amendment No. 2 to Restricted Company Guarantee and
         Security Agreement. Amendment No. 2 to the Restricted Company
         Guarantee and Security Agreement in substantially the form attached as
         Exhibit A shall have been duly executed and delivered by NCI and the
         Restricted Companies.

                  (i) Second Secured Intercreditor and Collateral Agency
         Agreement. The Second Secured Intercreditor and Collateral Agency
         Agreement in substantially the form attached as Exhibit B shall have
         been duly executed and delivered by NCI, the Restricted Companies, the
         Vendor Lenders named therein and the Collateral Agent.

                  (j) Fees and Expenses. Each Vendor and LCPI shall have
         received all fees and other amounts due and payable on or prior to the
         Amendment No. 3 Effective Date, including, to the extent invoiced,
         reimbursement or payment of all out-of-pocket expenses required to be
         reimbursed or paid by the Borrower hereunder.

Each Vendor and LCPI shall notify the Borrower and the Lenders of the Amendment
No. 3 Effective Date, and such notice shall be conclusive and binding.
Notwithstanding the foregoing, the obligations of Motorola to make additional
Tranche A Loans under the Vendor Financing Agreement as amended hereby shall
not become effective unless each of the foregoing conditions is satisfied (or
waived pursuant to Section 10.02) at or prior to 3:00 p.m., New York City time,
on August 29, 1997 (and, in the event such conditions are not so satisfied or
waived, the consent and amendments contemplated hereby shall not become
effective).

                  None of the foregoing conditions may be waived, amended or
modified except pursuant to an agreement or agreements in writing entered into
by the Restricted Companies and the Required Vendors.

                  Section 7. Miscellaneous. Except as herein provided, the
Vendor Financing Agreement shall remain unchanged and in full force and effect.
This Amendment No. 3 may be executed in any number of counterparts, all of
which taken together shall constitute one and the same amendatory instrument
and any of the parties hereto may execute this Amendment No. 3 by signing any
such counterpart. This Amendment No. 3 shall be governed by, and construed in
accordance with, the law of the State of New York.


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   19


                                     - 19 -


                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment No. 3 to Vendor Financing Agreement to be duly executed and delivered
as of the day and year first above written.

                                    NEXTEL COMMUNICATIONS, INC.

                                    By THOMAS J. SIDMAN
                                       ------------------------
                                       Name: Thomas J. Sidman
                                       Title: Vice President

                              RESTRICTED COMPANIES

                                    NEXTEL FINANCE COMPANY (successor to
                                     Fleet Call Corporation),

                                    By THOMAS J. SIDMAN
                                       ------------------------
                                       Name: Thomas J. Sidman
                                       Title: Vice President

                                    ADVANCED MOBILECOMM OF
                                     NORTH CAROLINA, INC.
                                    AIRLINK COMMUNICATIONS, INC.
                                     (successor to TRS, Inc.)
                                    AMERICAN MOBILE SYSTEMS,
                                     INCORPORATED (successor to Saber
                                     Communications, Inc.)
                                    DIAL CALL, INC.
                                    DIAL DISTANCE, INC.
                                    FC NEW YORK, INC. (successor to Metrocom
                                     Trunked Radio Communication Systems, Inc.)
                                    FCI 900, INC.
                                    FLEET CALL OF TEXAS, INC. (successor to
                                     FM Tower Company, Metrolink
                                     Communications Corporation and National
                                     Tower Trunking Systems, Inc.)


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   20


                                     - 20 -


                                 NEXTEL COMMUNICATIONS OF THE
                                  MID-ATLANTIC, INC. (successor to Dispatch
                                  Communications of Maryland, Inc., Dispatch
                                  Communications of Minnesota, Inc., Dispatch
                                  Communications of New England, Inc.,
                                  Dispatch Communications of Pennsylvania,Inc.)
                                 NEXTEL LICENSE HOLDINGS 1, INC.
                                 NEXTEL LICENSE HOLDINGS 2, INC.
                                  (successor to Comqor, Inc.)
                                 NEXTEL LICENSE HOLDINGS 3, INC.
                                  (successor to Dial Call Arkansas, Inc.,
                                  Custom Radio/Johnson Communications, Inc.,
                                  Dial Call Florida, Inc., Dial Call
                                  Kentucky, Inc., Dial Call Louisiana, Inc.,
                                  Dial Call Texas, Inc., Dial Call
                                  Virginia, Inc., Dial Call West Virginia, Inc.
                                  and U.S. Digital, Inc.)
                                 NEXTEL LICENSE HOLDINGS 4, INC.
                                 NEXTEL OF TEXAS, INC. (successor to Fort
                                  Worth Communications, Inc.)
                                 NEXTEL WEST CORP.
                                  (successor to Airwave Communications Corp.
                                  (Seattle), C-Call Corporation, Dispatch
                                  Communications of Arizona, Inc., ESMR Sub,
                                  Inc., Fleet Call of Utah, Inc., Fleet Call
                                  West, Inc., Mijac Enterprises, Inc., Mobile
                                  Radio of Illinois, Inc., Motorola SF, Inc.,
                                  Nextel Hawaii Acquisition Corp.,
                                  Nextel Utah Acquisition Corp., Nextel
                                  Western Acquisition Corp., OneComm
                                  Corporation, N.A., Powerfone
                                  Holdings, Inc., Powerfone, Inc.,
                                  Smart SMR of Illinois, Inc., Shoreland
                                  Communications, Inc. and Spectrum Resources
                                  of the Midwest, Inc.)
                                 SAFETY NET, INC.
                                 SMART SMR, INC.


                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   21


                                     - 21 -


                                                  SMART SMR OF CALIFORNIA, INC.
                                                  SMART SMR OF NEW YORK, INC.

                                                   By THOMAS J. SIDMAN
                                                     --------------------------
                                         Name:        Thomas J. Sidman
                                                     Title: Vice President

                                                  FORT WORTH TRUNKED RADIO
                                                   LIMITED PARTNERSHIP

                                                  By Nextel of Texas,Inc.,
                                                   a General Partner


                                                   By THOMAS J. SIDMAN
                                                     --------------------------
                                                     Name: Thomas J. Sidman
                                                     Title: Vice President

                                    VENDORS


                                                   MOTOROLA, INC.


                                                   By GARY B. TATJE 
                                                     --------------------------
                                                     Name: Gary B. Tatje
                                                     Title: Director, Customer
                                                            Financing

                                                   NTFC CAPITAL CORPORATION


                                                   By JERRY E. VAUGHN
                                                     --------------------------
                                                     Name: Jerry E. Vaughn
                                                     Title: SR. VP



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   22


                                     - 22 -


                  The undersigned, as assignee of certain of the Loans made by
Motorola under the above-referenced Vendor Financing Agreement, hereby consents
to the execution and delivery of the foregoing Amendment No. 3.

                                                LEHMAN COMMERCIAL PAPER, INC.


                                                By MICHELE SWANSON
                                                  -----------------------------
                                                  Name: Michele Swanson
                                                  Title: Authorized Signatory

                                                LEHMAN SYNDICATED LOANS INC.

                                                By: JAMES BOLAND
                                                   ----------------------------
                                                   Name: James P. Boland
                                                   Title: Vice President



                 Amendment No. 3 to Vendor Financing Agreement


<PAGE>   23

                                                                      EXHIBIT A



                     AMENDMENT NO. 2 TO RESTRICTED COMPANY
                        GUARANTEE AND SECURITY AGREEMENT


                  AMENDMENT NO. 2 TO RESTRICTED COMPANY GUARANTEE AND SECURITY
AGREEMENT dated as of August 29, 1997 between NEXTEL FINANCE COMPANY, a
corporation duly organized and validly existing under the laws of the State of
Delaware (the "Borrower"); each of the subsidiaries of Nextel Communications,
Inc. listed on the signature pages hereto under the caption "GUARANTORS"
(individually, a "Guarantor" and, collectively, the "Guarantors" and, together
with the Company, the "Restricted Companies"); and THE CHASE MANHATTAN BANK, as
collateral agent for the Vendors and Lenders party to the Loan Agreements
referred to below (in such capacity, together with its successors in such
capacity, the "Collateral Agent").

                  Nextel Communications, Inc. and the Restricted Companies are
parties to (i) an Amended, Restated and Consolidated Credit Agreement dated as
of September 27, 1996 (as modified and supplemented and in effect from time to
time, the "Vendor Financing Agreement") with Motorola, Inc., a Delaware
corporation ("Motorola"), and NTFC Capital Corporation, a Delaware corporation
("NTFC Capital" and, together with Motorola, the "Vendors"), providing, subject
to the terms and conditions thereof, for loans to be made by Motorola and NTFC
Capital to the Borrower in an aggregate principal amount not exceeding
$345,000,000 and (ii) a Credit Agreement dated as of September 27, 1996 (as
modified and supplemented and in effect from time to time, the "Credit
Agreement" and, together with the Vendor Financing Agreement, the "Loan
Agreements"), providing, subject to the terms and conditions thereof, for
extensions of credit (by means of loans and letters of credit) to be made by
the Lenders named therein (collectively, together with any entity that becomes
a "Lender" party to the Credit Agreement after the date thereof as provided
therein, the "Lenders") to the Borrower in an aggregate principal or face
amount not exceeding $1,655,000,000 (which, in the circumstances contemplated
by Section 7.01(f) thereof, may be increased to $1,905,000,000).

                  The Restricted Companies and the Collateral Agent are parties
to a Guarantee and Security Agreement dated as of September 27, 1996 (as
modified and supplemented and in effect from time to time, the "Restricted
Company Guarantee and Security Agreement") pursuant to which the Guarantors
have guaranteed the Guaranteed Obligations (as therein defined), and the
Restricted Companies have pledged and granted a security interest in the
Collateral (as so defined) as security for the Secured Obligations (as so
defined).



                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   24


                                     - 2 -


                  Concurrently with the execution and delivery hereof, (x) the
Vendor Financing Agreement is being amended to provide for an increase of
$50,000,000 in the amount of "Tranche A Loans" to be made thereunder by
Motorola (which increase is to be secured on a basis equal and ratable with the
existing Secured Obligations under the Restricted Company Guarantee and
Security Agreement), (y) the Credit Agreement is being amended to provide for
the making of "Tranche E Loans" thereunder in an aggregate amount equal to
$250,000,000 as contemplated by Section 7.01(f) thereof (which "Tranche E
Loans" are to be secured on a basis equal and ratable with the existing Secured
Obligations under the Restricted Company Guarantee and Security Agreement), and
(z) NCI, the Restricted Companies and the Vendor Lenders referred to therein
are entering into a Second Secured Vendor Financing Agreement dated as of
August 29, 1997 (the "Second Secured Vendor Financing Agreement"), providing
for the making by Motorola to the Borrower of "Tranche D Loans" in an aggregate
principal amount equal to $200,000,000 (which "Tranche D Loans" are to be
secured on a basis junior to the existing Secured Obligations under the
Restricted Company Guarantee and Security Agreement).

                  In that connection, the Restricted Companies and the
Collateral Agent (with the consent of the appropriate "Secured Parties" as
required by Section 7.02(b) of the Restricted Company Guarantee and Security
Agreement and Section 5.02(c) of the Intercreditor and Collateral Agency
Agreement) wish to amend the Restricted Company Guarantee and Security
Agreement in certain respects, and accordingly, the parties hereto hereby agree
as follows:

                  Section 1. Definitions. Except as otherwise defined in this
Amendment No. 2 to Restricted Company Guarantee and Security Agreement, terms
defined in the Restricted Company Guarantee and Security Agreement are used
herein as defined therein.

                  Section 2.  Amendments.  Subject to the satisfaction of the
condition precedent specified in Section 4 below, but effective as of the date
hereof, the Restricted Company Guarantee and Security Agreement shall be amended
as follows:

                  2.01 References Generally. References in the Restricted
Company Guarantee and Security Agreement to "this Agreement" (and indirect
references such as "hereunder", "hereby", "herein" and "hereof") shall be
deemed to be references to the Restricted Company Guarantee and Security
Agreement as amended hereby.

                  2.02 Definitions. Section 1.01 of the Restricted Company
Guarantee and Security Agreement is hereby amended by adding the following new
definitions (to the extent not already included in said Section 1.01) and
inserting the same in the appropriate alphabetical locations and amending the
following definitions (to the extent already included in said Section 1.01), as
follows:


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   25


                                     - 3 -



                  "Event of Default" means (x) an "Event of Default" under and
         as defined in the Credit Agreement or an "Event of Default" under and
         as defined in the Vendor Financing Agreement and (y) after the Senior
         Termination Date, an "Event of Default" under and as defined in the
         Second Secured Vendor Financing Agreement.

                  "Required Secured Parties" means (x) at any time prior to the
         Senior Termination Date, Secured Parties having Loans, LC Exposure and
         unused Commitments under the respective Loan Agreements representing
         at least 51% of the sum of the total Loans, LC Exposure and unused
         Commitments at such time and (y) at any time after the Senior
         Termination Date, Secured Parties having loans and unused commitments
         under the Second Secured Vendor Financing Agreement representing at
         least 51% of the sum of the total of such loans and commitments at
         such time.

                  "Second Secured Intercreditor and Collateral Agency
         Agreement" has the meaning assigned to such term in the Loan
         Agreements.

                  "Second Secured Obligations" means, collectively, (a) in the
         case of the Borrower, the principal of and interest on the loans made
         by the Secured Parties to the Borrower pursuant to the Second Secured
         Vendor Financing Agreement, (b) in the case of each Guarantor, all
         obligations of such Guarantor in respect of its Guarantee under
         Article II of the obligations of the Borrower under the Second Secured
         Vendor Financing Agreement and, after the Senior Termination Date, of
         the obligations of each Restricted Company under the Security
         Documents and (c) in the case of each Restricted Company, but only
         after the Senior Termination Date, all other obligations of such
         Restricted Company to the Secured Parties and the Agents hereunder.

                  "Second Secured Vendor Financing Agreement" has the meaning
         assigned to such term in the Loan Agreements.

                  "Secured Obligations" means, collectively, the Senior Secured
         Obligations and the Second Secured Obligations.

                  "Secured Parties" means, collectively, (i) the Vendors, (ii)
         the Lenders and (iii) the Vendor Lenders from time to time party to
         the Second Secured Vendor Financing Agreement. This definition shall,
         effective upon the execution and delivery of Amendment No. 2 hereto,
         override the definition of the term "Secured Parties" set forth in the
         preamble to this Agreement.

                  "Senior Secured Obligations" means, collectively, (a) in the
         case of the Borrower, the principal of and interest on the Loans made
         by the Secured Parties to


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   26


                                     - 4 -


         the Borrower, all LC Disbursements and all other amounts from time to
         time owing to the Secured Parties or the Agents by the Borrower under
         the Loan Documents or any Hedging Agreement, (b) in the case of each
         Guarantor, all obligations of such Guarantor in respect of its
         Guarantee under Article II of the obligations of the Borrower under
         the Loan Documents and (c) in the case of each Restricted Company, all
         other obligations of such Restricted Company to the Secured Parties
         and the Agents hereunder.

                  "Senior Termination Date" means the date (or the time on such
         date) upon which the Senior Secured Obligations shall have been paid
         in full and the Commitments shall have been terminated.

                  2.03 The Guarantee. Sections 2.01 and 2.05, respectively, of
the Restricted Company Guarantee and Security Agreement are hereby amended to
read in their entirety as follows:

                  "SECTION 2.01. The Guarantee. The Guarantors hereby jointly
         and severally guarantee to each Secured Party and the Agents and their
         respective successors and assigns the prompt payment in full when due
         (whether at stated maturity, by acceleration or otherwise) of the
         principal of and interest on the Loans made by the Secured Parties to
         the Borrower, all LC Disbursements and all other amounts from time to
         time owing to the Secured Parties or either Agent by the Borrower
         under the Loan Agreements or any other Loan Document, all obligations
         of the Borrower to any Secured Party under any Hedging Agreement and
         all obligations of the Borrower to any Secured Party under the Second
         Secured Vendor Financing Agreement, in each case strictly in
         accordance with the terms thereof (such principal, interest, other
         amounts and obligations being herein collectively called the
         "Guaranteed Obligations"). The Guarantors hereby further jointly and
         severally agree that if the Borrower shall fail to pay in full when
         due (whether at stated maturity, by acceleration or otherwise) any of
         the Guaranteed Obligations, the Guarantors will promptly pay the same,
         without any demand or notice whatsoever, and that in the case of any
         extension of time of payment or renewal of any of the Guaranteed
         Obligations, the same will be promptly paid in full when due (whether
         at extended maturity, by acceleration or otherwise) in accordance with
         the terms of such extension or renewal.

                  SECTION 2.05. Remedies. The Guarantors jointly and severally
         agree that, as between the Guarantors and the Secured Parties, the
         obligations of the Borrower under the Loan Agreements and the Second
         Secured Vendor Financing Agreement may be declared to be forthwith due
         and payable as provided in Article VIII of the respective Loan
         Agreements or Second Secured Vendor Financing Agreement, as the


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   27


                                     - 5 -


         case may be (and shall be deemed to have become automatically due and
         payable in the circumstances provided in said Articles VIII) for
         purposes of Section 2.01 notwithstanding any stay, injunction or other
         prohibition preventing such declaration (or such obligations from
         becoming automatically due and payable) as against the Borrower and
         that, in the event of such declaration (or such obligations being
         deemed to have become automatically due and payable), such obligations
         (whether or not due and payable by the Borrower) shall forthwith
         become due and payable by the Guarantors for purposes of said Section
         2.01."

                  2.04 Sale Proceeds Reinvestment Account. Paragraph (a) of
Section 5.01 of the Restricted Company Guarantee and Security Agreement is
hereby amended to read in its entirety as follows:

                  "(a) prior to the Senior Termination Date, the Restricted
         Companies shall deposit into the Sale Proceeds Reinvestment Account,
         the Net Cash Payments of any Disposition (as each of such capitalized
         terms is defined in the respective Loan Agreements on the date hereof
         and in the Second Secured Vendor Financing Agreement on the date
         thereof) that, pursuant to clause (y) of Section 2.09(b)(ii) of the
         respective Loan Agreements, the Restricted Companies elect to deliver
         to the Collateral Agent pending reinvestment of such Net Cash Payments
         into replacement assets (and, after the Senior Termination Date, the
         Restricted Companies shall deposit into the Sale Proceeds Reinvestment
         Account, the Net Cash Payments of any such Disposition that, pursuant
         to clause (y) of Section 2.09(b)(ii) of the Second Secured Vendor
         Financing Agreement, the Restricted Companies elect to deliver to the
         Collateral Agent pending reinvestment of such Net Cash Payments into
         replacement assets);"

                  2.05 Tax Proceeds Reinvestment Account. Paragraph (c) of
Section 5.01 of the Restricted Company Guarantee and Security Agreement is
hereby amended to read in its entirety as follows:

                  "(c) the Restricted Companies shall deposit into the Tax
         Proceeds Account, that portion of the cash payment received by the
         Restricted Companies directly or indirectly in connection with any
         Disposition (as such term in defined in the respective Loan Agreements
         on the date hereof and in the Second Secured Vendor Financing
         Agreement on the date thereof) that represents the income or other
         taxes estimated to be payable by the Restricted Companies as a result
         of such Disposition and that are deducted in determining the amount of
         "Net Cash Payments" (as so defined) with respect to such Disposition;"



                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   28


                                     - 6 -


                  2.06 Application of Monies in Collateral Accounts. Section
5.02 of the Restricted Company Guarantee and Security Agreement is hereby
amended to read in its entirety as follows:

                  "SECTION 5.02. Application of Monies in Collateral Accounts.
         The balance from time to time in the Collateral Accounts shall
         constitute part of the Collateral hereunder, shall not constitute
         payment of the Secured Obligations until applied to the Secured
         Obligations as hereinafter provided and shall be released to the
         Restricted Companies (or otherwise be subject to withdrawal) only as
         follows:

                           (a) prior to the Senior Termination Date, monies and
                  investments in the Sale Proceeds Reinvestment Account may be
                  withdrawn only in connection with a reinvestment transaction
                  permitted under Section 2.09(b)(ii) of the respective Loan
                  Agreements, or for application to the prepayment of Loans (or
                  cover for Letters of Credit) as contemplated by said Section
                  2.09(b)(ii) (and, after the Senior Termination Date, such
                  monies and investments may be withdrawn only in connection
                  with a reinvestment transaction permitted under Section
                  2.09(b)(ii) of the Second Secured Vendor Financing Agreement
                  as contemplated by said Section 2.09(b)(ii)), provided that
                  (without the consent of the Required Secured Parties) the
                  Collateral Agent shall not be obligated to release such
                  monies for application to a reinvestment transaction at any
                  time after the occurrence and during the continuance of any
                  Event of Default;

                           (b) monies and investments in the Casualty Event
                  Proceeds Account may be withdrawn only in connection with the
                  replacement, restoration and repair of the property affected
                  by such Casualty Event (the "Damaged Property"), or, prior to
                  the Senior Termination Date, for application to the
                  prepayment of Loans (or cover for Letters of Credit) pursuant
                  to Section 2.09(a) of the Loan Agreements in such manner as
                  the Borrower shall elect (and, after the Senior Termination
                  Date, for application to the prepayment of loans under the
                  Second Secured Vendor Financing Agreement pursuant to Section
                  2.09(a) thereof in such manner as the Borrower shall elect),
                  and if the respective Restricted Company elects to so replace
                  or restore and repair Damaged Property, any such monies shall
                  be advanced to such Restricted Company by the Collateral
                  Agent in periodic installments upon compliance by such
                  Restricted Company with such reasonable conditions to
                  disbursement as may be imposed by the Collateral Agent,
                  including, but not limited to, reasonable retention amounts
                  and receipt of lien releases, provided that (without the
                  consent of the Required Secured Parties) the Collateral Agent
                  shall not be obligated to release such monies for application
                  to any such


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   29


                                     - 7 -


                  replacement, restoration, repair or prepayment at any time
                  after the occurrence and during the continuance of any Event
                  of Default;

                           (c) prior to the Senior Termination Date, monies and
                  investments in the Tax Proceeds Account may be withdrawn only
                  in connection with the payment of taxes as contemplated by
                  the definition of "Net Cash Payments" in the respective Loan
                  Agreements, or for application to the prepayment of Loans (or
                  cover for Letters of Credit) as contemplated by Section
                  2.09(b)(ii) thereof (and, after the Senior Termination Date,
                  such monies and investments may be withdrawn only in
                  connection with the payment of taxes as contemplated by the
                  definition of "Net Cash Payments" in the Second Secured
                  Vendor Financing Agreement, or for application to the
                  prepayment of Loans under the Second Secured Vendor Financing
                  Agreement, as contemplated by Section 2.09(b)(ii) thereof),
                  provided that (without the consent of the Required Secured
                  Parties) the Collateral Agent shall not be obligated to
                  release such monies for application to the payment of taxes
                  at any time after the occurrence and during the continuance
                  of any Event of Default;

                           (d) monies and investments in the Letter of Credit
                  Account may be applied only to the payment of LC
                  Disbursements for which the respective Issuing Banks have not
                  been reimbursed by the Borrower or, but only with the consent
                  of the Required Revolving Credit Lenders, to the payment of
                  other Secured Obligations and, after the payment in full of
                  all LC Disbursements and the expiration or termination of all
                  Letters of Credit, to the payment of any other Secured
                  Obligations as shall at the time be payable hereunder; and

                           (e) monies and investments in the Concentration
                  Account may be withdrawn only (I) in connection with
                  remitting the same to bank deposit accounts (such as payroll
                  and other accounts) maintained by the Restricted Companies
                  for use in the ordinary course of business, (II) to make
                  Capital Expenditures, (III) prior to the Senior Termination
                  Date to make acquisitions and investments permitted under
                  Section 7.04 of the respective Loan Agreements (and, after
                  the Senior Termination Date, to make acquisitions and
                  investments permitted under Section 7.04 of the Second
                  Secured Vendor Financing Agreement), (IV) prior to the Senior
                  Termination Date to make Restricted Payments permitted under
                  Section 7.05 of the respective Loan Agreements (and, after
                  the Senior Termination Date, to make Restricted Payments
                  permitted under Section 7.05 of the Second Secured Vendor
                  Financing Agreement), or (V) prior to the Senior Termination
                  Date to make payments or prepayments of principal, interest
                  or other amounts in respect of Indebtedness (including Loans)
                  or Hedging Agreements permitted under the


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   30


                                     - 8 -


                  respective Loan Agreements (and, after the Senior Termination
                  Date, to make payments or prepayments of principal, interest
                  or other amounts in respect of Indebtedness (including the
                  loans under the Second Secured Vendor Financing Agreement) or
                  Hedging Agreements permitted under the Second Secured Vendor
                  Financing Agreement).

         In connection with any release of monies in any of the Collateral
         Accounts described above, the Collateral Agent shall be entitled to
         rely upon a certificate of a Financial Officer (and upon such other
         evidence, if any, as the Collateral Agent shall deem appropriate). At
         any time following the occurrence and during the continuance of an
         Event of Default, the Collateral Agent may (and, if instructed by the
         Required Secured Parties shall) in its (or their) discretion apply or
         cause to be applied (subject to collection) the balance from time to
         time outstanding to the credit of any of the Collateral Accounts to
         the payment of the Secured Obligations in the manner specified in
         Section 6.09."

                  2.07 Other Financing Statements and Liens. Section 6.02 of
the Restricted Company Guarantee and Security Agreement is hereby amended to
read in its entirety as follows:

                  "SECTION 6.02. Other Financing Statements and Liens. Except
         as otherwise permitted under Section 7.02 of the respective Loan
         Agreements or the Second Secured Vendor Financing Agreement, without
         the prior written consent of the Collateral Agent (granted with the
         authorization of the Required Secured Parties), no Restricted Company
         shall file or suffer to be on file, or authorize or permit to be filed
         or to be on file, in any jurisdiction, any financing statement or like
         instrument with respect to the Collateral in which the Collateral
         Agent is not named as the sole secured party for the benefit of the
         Secured Parties."

                  2.08 Removals. Section 6.07 of the Restricted Company
Guarantee and Security Agreement is hereby amended to read in its entirety as
follows:

                  "SECTION 6.07. Removals, Etc. Without at least 30 days' prior
         written notice to the Collateral Agent, no Restricted Company shall
         (i) maintain any of its books and records with respect to the
         Collateral at any office or maintain its principal place of business
         other than at the address for notices to the Borrower specified in
         Section 10.01 of the respective Loan Agreements or the Second Secured
         Vendor Financing Agreement, or at one of the locations identified in
         Annex 3 or in transit from one of such locations to another or (ii)
         change its name, or the name under which it does business, from the
         name shown on the signature pages hereto."



                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   31


                                     - 9 -


                  2.09 Application of Proceeds. Section 6.09 of the Restricted
Company Guarantee and Security Agreement is hereby amended to read in its
entirety as follows:

                  "SECTION 6.09. Application of Proceeds. Except as otherwise
         herein expressly provided, the proceeds of any collection, sale or
         other realization of all or any part of the Collateral pursuant
         hereto, and any other cash at the time held by the Collateral Agent
         under Article V or this Article VI, shall be applied by the Collateral
         Agent:

                           First, to the payment of the costs and expenses of
                  such collection, sale or other realization, including
                  reasonable out-of-pocket costs and expenses of the Collateral
                  Agent and the fees and expenses of its agents and counsel,
                  and all expenses incurred and advances made by the Collateral
                  Agent in connection therewith;

                           Next, to the payment in full of the Senior Secured
                  Obligations, in each case equally and ratably in accordance
                  with the respective amounts thereof then due and owing or as
                  the Secured Parties holding the same may otherwise agree;

                           Next, to the payment in full of the Second Secured
                  Obligations, in each case equally and ratably in accordance
                  with the respective amounts thereof then due and owing or as
                  the Secured Parties holding the same may otherwise agree; and

                           Finally, to the payment to the respective Restricted
                  Company, or their respective successors or assigns, or as a
                  court of competent jurisdiction may direct, of any surplus
                  then remaining.

                           As used in this Article VI, "proceeds" of Collateral
         shall mean cash, securities and other property realized in respect of,
         and distributions in kind of, Collateral, including any thereof
         received under any reorganization, liquidation or adjustment of debt
         of the Restricted Companies or any issuer of or obligor on any of the
         Collateral."

                  2.10 Termination. Section 6.12 of the Restricted Company
Guarantee and Security Agreement is hereby amended to read in its entirety as
follows:

                  "SECTION 6.12.  Termination.  When all Secured Obligations
         shall have been paid in full and the Commitments of the Secured Parties
         under the respective Loan Agreements (and the commitments of the
         Secured Parties under the Second Secured


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   32


                                     - 10 -


         Vendor Financing Agreement) shall have expired or been terminated,
         this Agreement shall terminate, and the Collateral Agent shall
         forthwith cause to be assigned, transferred and delivered, against
         receipt but without any recourse, warranty or representation
         whatsoever, any remaining Collateral and money received in respect
         thereof, to or on the order of the respective Restricted Company. The
         Collateral Agent shall also execute and deliver to respective
         Restricted Company upon such termination such Uniform Commercial Code
         termination statements and such other documentation as shall be
         reasonably requested by the respective Restricted Company to effect
         the termination and release of the Liens on the Collateral."

                  2.11 Certain Regulatory Requirements. Section 7.11(a) of the
Restricted Company Guarantee and Security Agreement is hereby amended to read
in its entirety as follows:

                  "(a) Each Restricted Company shall take all action that the
         Collateral Agent may reasonably request in the exercise of its rights
         and remedies hereunder, which include the right to require such
         Restricted Company to transfer or assign the FCC Licenses or the PUC
         Authorizations to any party or parties. In furtherance of this right,
         each Restricted Company shall (i) cooperate fully with the Collateral
         Agent in obtaining all approvals and consents from the FCC and each
         other Governmental Authority that the Collateral Agent may deem
         necessary or advisable to accomplish any such transfer or assignment
         of the FCC Licenses or the PUC Authorizations and (ii) prepare,
         execute and file with the FCC and any other Governmental Authority any
         application, request for consent, certificate or instrument that the
         Collateral Agent may deem necessary or advisable to accomplish any
         such transfer or assignment of the FCC Licenses or the PUC
         Authorizations. If any Restricted Company fails to execute such
         applications, requests for consent, certificates or instruments, the
         clerk of any court that has jurisdiction over the Loan Documents (or,
         after the Senior Termination Date, over the Second Secured Vendor
         Financing Agreement and the Security Documents) may, upon an ex parte
         request by the Collateral Agent, execute and file the same on behalf
         of such Restricted Company."

                  2.12 Additional Guarantors. Section 7.12 of the Restricted
Company Guarantee and Security Agreement is hereby amended to read in its
entirety as follows:

                  "SECTION 7.12. Additional Guarantors. As contemplated by
         Section 6.11(a) of the respective Loan Agreements (and by Section
         6.11(a) of the Second Secured Vendor Financing Agreement), in the
         event that any Restricted Company shall form or acquire any new
         subsidiary after the date hereof, such Restricted Company will cause
         such new subsidiary to execute and deliver to the Collateral Agent a
         Joinder Agreement in the form of Exhibit E to the respective Loan
         Agreements or Exhibit E


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   33


                                     - 11 -


         to the Second Secured Vendor Financing Agreement (and, thereby, to
         become a party to the Loan Agreements and to the Second Secured Vendor
         Financing Agreement as a "Restricted Company" thereunder, and to this
         Agreement, the Intercreditor and Collateral Agency Agreement and the
         Second Secured Intercreditor and Collateral Agency Agreement, as a
         "Guarantor" hereunder and thereunder, and to pledge and grant a
         security interest in its property pursuant to this Agreement to the
         Collateral Agent for the benefit of the Secured Parties). Accordingly,
         upon the execution and delivery of any such Joinder Agreement by any
         such new subsidiary, such new subsidiary shall automatically and
         immediately, and without any further action on the part of any Person,
         become a "Guarantor" under and for all purposes of this Agreement, and
         Annexes 1, 2 and 3 hereto shall be deemed to be supplemented in the
         manner specified in said Joinder Agreements."

                  Section 3. Representations and Warranties. Each Restricted
Company represents and warrants to the Secured Parties and the Collateral Agent
that the representations and warranties set forth in Article III of the
Restricted Company Guarantee and Security Agreement are true and complete on
the date hereof as if made on and as of the date hereof (or if any such
representation and warranty is expressly stated to have been made as of a
specific date, as of such date) and as if each reference in said Article III to
"this Agreement" included reference to the Restricted Company Guarantee and
Security Agreement as amended by this Amendment No. 2.

                  Section 4. Conditions Precedent. As provided in Section 2
above, the amendments to the Restricted Company Guarantee and Security
Agreement set forth in said Section 2 shall become effective, as of the date
hereof, upon the execution and delivery of this Amendment No. 2 to Restricted
Company Guarantee and Security Agreement by each of the Restricted Companies
and the Collateral Agent.

                  Section 5. Amendment to Collateral Assignment of Leasehold
Interests. The Collateral Assignment of Leasehold Interests referred to in the
last sentence of Section 6.13 of the Restricted Company Guarantee and Security
Agreement (as amended hereby) shall be deemed to be amended to the extent
necessary to reference the Second Secured Vendor Financing Agreement and to
include the obligations of the Borrower under the Second Secured Vendor
Financing Agreement as "Secured Obligations" under and as defined therein,
subject to the Second Secured Intercreditor and Collateral Agency Agreement.

                  Section 6. Miscellaneous. Except as herein provided, the
Restricted Company Guarantee and Security Agreement shall remain unchanged and
in full force and effect. This Amendment No. 2 to Restricted Company Guarantee
and Security Agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same amendatory instrument
and any of the parties hereto may execute this Amendment


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   34


                                     - 12 -


No. 2 to Restricted Company Guarantee and Security Agreement by signing any
such counterpart. This Amendment No. 2 to Restricted Company Guarantee and
Security Agreement shall be governed by, and construed in accordance with, the
law of the State of New York.


                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   35


                                     - 13 -



                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment No. 2 to Restricted Company Guarantee and Security Agreement to be
duly executed and delivered as of the day and year first above written.

                                   NEXTEL COMMUNICATIONS, INC.

                                    By
                                      ---------------------------------
                                      Name:
                                      Title:

                              RESTRICTED COMPANIES

                                   NEXTEL FINANCE COMPANY (successor to
                                    Fleet Call Corporation),

                                    By
                                      ---------------------------------
                                      Name:
                                      Title:


                                   ADVANCED MOBILECOMM OF                      
                                     NORTH CAROLINA, INC.                      
                                   AIRLINK COMMUNICATIONS, INC.                
                                     (successor to TRS, Inc.)                  
                                   AMERICAN MOBILE SYSTEMS,                    
                                     INCORPORATED (successor to Saber          
                                     Communications, Inc.)                     
                                   DIAL CALL, INC.                             
                                   DIAL DISTANCE, INC.                         
                                   FC NEW YORK, INC. (successor to Metrocom    
                                     Trunked Radio Communication Systems, Inc.)
                                   FCI 900, INC.                               
                                   FLEET CALL OF TEXAS, INC. (successor to     
                                     FM Tower Company, Metrolink               
                                     Communications Corporation and National   
                                     Tower Trunking Systems, Inc.)             
                                           
                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   36


                                     - 14 -



                                NEXTEL COMMUNICATIONS OF THE
                                  MID-ATLANTIC, INC. (successor to Dispatch
                                  Communications of Maryland, Inc., Dispatch
                                  Communications of Minnesota, Inc., Dispatch
                                  Communications of New England, Inc.,       
                                  Dispatch Communications of Pennsylvania,Inc.)
                                NEXTEL LICENSE HOLDINGS 1, INC.           
                                NEXTEL LICENSE HOLDINGS 2, INC.           
                                  (successor to Comqor, Inc.)             
                                NEXTEL LICENSE HOLDINGS 3, INC.           
                                  (successor to Dial Call Arkansas, Inc., 
                                  Custom Radio/Johnson Communications, Inc., 
                                  Dial Call Florida, Inc., Dial Call         
                                  Kentucky, Inc., Dial Call Louisiana, Inc., 
                                  Dial Call Texas, Inc., Dial Call           
                                  Virginia, Inc., Dial Call West Virginia, Inc.
                                  and U.S. Digital, Inc.)                   
                                NEXTEL LICENSE HOLDINGS 4, INC.             
                                NEXTEL OF TEXAS, INC. (successor to Fort    
                                  Worth Communications, Inc.)               
                                NEXTEL WEST CORP.                           
                                  (successor to Airwave Communications Corp.
                                  (Seattle), C-Call Corporation, Dispatch
                                  Communications of Arizona, Inc., ESMR Sub,
                                  Inc., Fleet Call of Utah, Inc., Fleet Call
                                  West, Inc., Mijac Enterprises, Inc., Mobile
                                  Radio of Illinois, Inc., Motorola SF, Inc.,
                                  Nextel Hawaii Acquisition Corp., Nextel
                                  Utah Acquisition Corp., Nextel
                                  Western Acquisition Corp., OneComm
                                Corporation, N.A., Powerfone
                                  Holdings, Inc., Powerfone, Inc.,          
                                  Smart SMR of Illinois, Inc., Shoreland    
                                  Communications, Inc. and Spectrum Resources
                                  of the Midwest, Inc.)                      
                                SAFETY NET, INC.                             
                                SMART SMR, INC.                              
                                   
                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   37


                                     - 15 -


                                SMART SMR OF CALIFORNIA, INC.
                                SMART SMR OF NEW YORK, INC.

                                 By
                                   ---------------------------------------
                                   Name:
                                   Title:

                                FORT WORTH TRUNKED RADIO
                                 LIMITED PARTNERSHIP

                                By Nextel of Texas,
                                 a General Partner


                                 By
                                   ----------------------------------------
                                   Name:
                                   Title:


                        COLLATERAL AGENT

                                THE CHASE MANHATTAN BANK, as
                                 Collateral Agent

                                 By
                                   ----------------------------------------
                                   Name:
                                   Title:



                     Amendment No. 2 to Restricted Company
                        Guarantee and Security Agreement


<PAGE>   38

                                                                      EXHIBIT B



          SECOND SECURED INTERCREDITOR AND COLLATERAL AGENCY AGREEMENT

                  SECOND SECURED INTERCREDITOR AND COLLATERAL AGENCY AGREEMENT
dated as of August 29, 1997 between NEXTEL FINANCE COMPANY, a corporation duly
organized and validly existing under the laws of the State of Delaware (the
"Borrower"); each of the subsidiaries of Nextel Communications, Inc. listed on
the signature pages hereto under the caption "INITIAL GUARANTORS" (the "Initial
Guarantors"); each of the additional entities, if any, that becomes a
"Guarantor" hereunder as contemplated by Section 7.12 of the below-referenced
Restricted Company Guarantee and Security Agreement (each an "Additional
Guarantor" and together with the Initial Guarantors, the "Guarantors"; the
Guarantors together with the Borrower, being herein called the "Restricted
Companies"); MOTOROLA, INC., a Delaware corporation ("Motorola"); each other
VENDOR LENDER that shall at any time, as contemplated by Section 5.04, be
deemed to be a party hereto (collectively, including Motorola, the "Vendor
Lenders"); and THE CHASE MANHATTAN BANK, as collateral agent for the Vendors
and for the Lenders referred to below (in such capacity, together with its
successors in such capacity, the "Collateral Agent").

                  Nextel Communications, Inc. ("NCI") and the Restricted
Companies are parties to a Second Secured Vendor Financing Agreement dated as
of August 29, 1997 (as modified and supplemented and in effect from time to
time, the "Second Secured Vendor Financing Agreement") with Motorola and the
other Vendor Lenders referred to therein, providing, subject to the terms and
conditions thereof, for loans to be made by the Vendor Lenders to the Borrower
in an aggregate principal amount not exceeding $200,000,000. NCI and the
Restricted Companies are also parties to a Vendor Financing Agreement and a
Credit Agreement (as such respective capitalized terms are defined herein),
providing, respectively, for loans and extensions of credit to be made by the
"Lenders" and "Vendors" under such Agreements to the Borrower in an aggregate
principal amount up to but not exceeding, respectively, $395,000,000 and
$1,905,000,000. This Agreement applies to Motorola solely in its capacity as a
Vendor Lender under the Second Secured Vendor Financing Agreement and shall not
affect, in any way, the rights of Motorola in its capacity as a Vendor under
the Vendor Financing Agreement.

                  The obligations of the Restricted Companies under the Credit
Agreement and the Vendor Financing Agreement are entitled to the benefits of
collateral security provided pursuant to the Security Documents referred to
below. The parties hereto intend that the collateral security provided by said
Security Documents shall also secure, with a ranking second to that of the
obligations under the Vendor Financing Agreement and Credit Agreement, the
obligations of the Restricted Companies under the Second Secured Vendor
Financing Agreement. In that connection, the parties hereto wish to provide for
the appointment of the Collateral Agent by the Vendor Lenders and for certain
other matters


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   39



                                     - 2 -



relating to the security interests provided by the Security Documents.
Accordingly, the parties hereto agree as follows:


                                   ARTICLE I

                                  Definitions

                  SECTION 1.01.  Defined Terms.  As used in this Agreement, the
following terms have the meanings specified below:

                  "Affiliate" means, with respect to a specified Person,
another Person that directly, or indirectly through one or more intermediaries,
Controls or is Controlled by or is under common Control with the Person
specified.

                  "Agents" means the Administrative Agent under the Credit
Agreement and the Collateral Agent hereunder.

                  "Applicable Percentage" means with respect to any Vendor
Lender in respect of any indemnity claim under Section 7.03(a) of the
Restricted Company Guarantee and Security Agreement arising out of an action or
omission of the Collateral Agent under any Second Secured Loan Document, the
percentage of the "Tranche D Commitments" under the Second Secured Vendor
Financing Agreement represented by the aggregate amount of such Vendor Lender's
"Tranche D Commitment" under the Second Secured Vendor Financing Agreement. If
the "Tranche D Commitments" under the Second Secured Vendor Financing Agreement
have terminated or expired, the Applicable Percentages shall be determined
based upon the "Tranche D Commitments" most recently in effect, giving effect
to any assignments.

                  "Commitments" means the "Commitments" of the Lenders under
the Credit Agreement and the "Commitments" of the Vendors under the Vendor
Financing Agreement.

                  "Control" means the possession, directly or indirectly, of
the power to direct or cause the direction of the management or policies of a
Person, whether through the ability to exercise voting power, by contract or
otherwise. "Controlling" and "Controlled" have meanings correlative thereto.

                  "Credit Agreement" means the Credit Agreement dated as of
September 27, 1996, among NCI, the Restricted Companies, the lenders party
thereto, Toronto Dominion (Texas) Inc., as Administrative Agent, and The Chase
Manhattan Bank, as Collateral Agent.


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   40



                                     - 3 -




                  "Credit Parties" means NCI and the Restricted Companies.

                  "Default" means any event or condition which constitutes an
Event of Default or which upon notice, lapse of time or both would, unless
cured or waived, become an Event of Default.

                  "Event of Default" means (x) an "Event of Default" under and
as defined in the Credit Agreement or an "Event of Default" under and as
defined in the Vendor Financing Agreement and (y) after the Senior Termination
Date, "Event of Default" under and as defined in the Second Secured Vendor
Financing Agreement.

                  "Governmental Authority" means the government of the United
States of America, any other nation or any political subdivision thereof,
whether state or local, and any agency, authority, instrumentality, regulatory
body, court, central bank or other entity exercising executive, legislative,
judicial, taxing, regulatory or administrative powers or functions of or
pertaining to government.

                  "Hedging Agreement" has the meaning assigned to such term in
the Credit Agreement.

                  "LC Disbursement" has the meaning assigned to such term in the
Credit Agreement.

                  "LC Exposure" has the meaning assigned to such term in the
Credit Agreement.

                  "Lien" means, with respect to any asset, (a) any mortgage,
deed of trust, lien, pledge, hypothecation, encumbrance, charge or security
interest in, on or of such asset, (b) the interest of a vendor or a lessor
under any conditional sale agreement, capital lease or title retention
agreement (or any financing lease having substantially the same economic effect
as any of the foregoing) relating to such asset and (c) in the case of
securities, any purchase option, call or similar right of a third party with
respect to such securities.

                  "Loan Agreements" means, collectively, the Credit Agreement
and the Vendor Financing Agreement.

                  "Loan Documents" means the Loan Agreements, any promissory
notes evidencing Loans under any Loan Agreement and the Security Documents.



          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   41

                                     - 4 -



                  "Loans" means the "Loans" made by the Lenders to the Borrower
under the Credit Agreement and the "Loans" made by the Vendors to the Borrower
under the Vendor Financing Agreement.

                  "Mortgages" means, collectively, one or more assignments of
lease, mortgages, deeds of trust, deeds to secure debt and the like executed by
a Restricted Company in favor of the Collateral Agent (or a trustee for the
benefit of the Collateral Agent), and covering interests in real property held
by such Restricted Company as collateral security for the Secured Obligations,
in each case in such form as shall be satisfactory to the Collateral Agent.

                  "Person" means any natural person, corporation, limited
liability company, trust, joint venture, association, company, partnership,
Governmental authority or other entity.

                  "Related Parties" means, with respect to any specified
Person, such Person's Affiliates and the respective directors, officers,
employees, agents and advisors of such Person and such Person's Affiliates.

                  "Required Secured Parties" means (x) at any time prior to the
Senior Termination Date, Secured Parties having Loans, LC Exposure and unused
Commitments under the respective Loan Agreements representing at least 51% of
the sum of the total Loans, LC Exposure and unused Commitments at such time and
(y) at any time after the Senior Termination Date, Secured Parties having loans
and unused commitments under the Second Secured Vendor Financing Agreement
representing at least 51% of the sum of the total of such loans and commitments
at such time.

                  "Required Vendor Lenders" means, at any time, Vendor Lenders
having "Tranche D Loans" and unused "Tranche D Commitments" under the Second
Secured Vendor Financing Agreement representing at least 51% of the sum of the
total "Tranche D Loans" and unused "Tranche D Commitments" at such time.

                  "Restricted Company Guarantee and Security Agreement" means
the Restricted Company Guarantee and Security Agreement dated as of September
27, 1996 between the Restricted Companies and the Collateral Agent.

                  "Second Secured Loan Documents" means the Second Secured
Vendor Financing Agreement, any promissory notes evidencing Loans under the
Second Secured Vendor Financing Agreement and the Security Documents.



          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   42

                                     - 5 -



                  "Second Secured Obligations" means, collectively, (a) in the
case of the Borrower, the principal of and interest on the loans made by the
Secured Parties to the Borrower pursuant to the Second Secured Vendor Financing
Agreement, (b) in the case of each Guarantor, all obligations of such Guarantor
in respect of its Guarantee under Article II of the Restricted Company Guaranty
and Security Agreement of the obligations of the Borrower under the Second
Secured Vendor Financing Agreement and, after the Senior Termination Date, of
the obligations of each Restricted Company under the Security Documents and (c)
in the case of each Restricted Company, but only after the Senior Termination
Date, all other obligations of such Restricted Company to the Secured Parties
and the Collateral Agent under the Restricted Company Guaranty and Security
Agreement.

                  "Secured Obligations" means, collectively, the Senior Secured
Obligations and the Second Secured Obligations.

                  "Secured Parties" means, collectively, the Lenders from time
to time party to the Credit Agreement, the Vendors from time to time party to
the Vendor Financing Agreement, and the Vendor Lenders from time to time party
to Second Secured Vendor Financing Agreement.

                  "Security Documents" means this Agreement, the Restricted
Company Guarantee and Security Agreement, the Mortgages and all Uniform
Commercial Code financing statements required by any of such instruments to be
filed with respect to the security interests in personal property and fixtures
created pursuant thereto.

                  "Senior Secured Obligations" means, collectively, (a) in the
case of the Borrower, the principal of and interest on the Loans made by the
Secured Parties to the Borrower, all LC Disbursements and all other amounts
from time to time owing to the Secured Parties or the Agents by the Borrower
under the Loan Documents or any Hedging Agreement, (b) in the case of each
Guarantor, all obligations of such Guarantor in respect of its Guarantee under
Article II of the Restricted Company Guaranty and Security Agreement of the
obligations of the Borrower under the Loan Documents and (c) in the case of
each Restricted Company, all other obligations of such Restricted Company to
the Secured Parties and the Agents under the Restricted Company Guaranty and
Security Agreement.

                  "Senior Termination Date" means the date (or the time on such
date) upon which the Senior Secured Obligations shall have been paid in full
and the Commitments shall have been terminated.

                  "subsidiary" means, with respect to any Person (the "parent")
at any date, any corporation, limited liability company, partnership,
association or other entity the accounts of


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   43

                                     - 6 -



which would be consolidated with those of the parent in the parent's
consolidated financial statements if such financial statements were prepared in
accordance with GAAP as of such date, as well as any other corporation, limited
liability company, partnership, association or other entity (a) of which
securities or other ownership interests representing more than 50% of the
ordinary voting power or, in the case of a partnership, more than 50% of the
general partnership interests are, as of such date, owned, controlled or held,
or (b) that is, as of such date, otherwise Controlled, by the parent or one or
more subsidiaries of the parent or by the parent and one or more subsidiaries
of the parent.

                  "Subsidiary" means any subsidiary of the Borrower.

                  "Vendor Equipment Agreements" has the meaning assigned to
such term in the Vendor Financing Agreement.

                  "Vendor Financing Agreement" means the Amended, Restated and
Consolidated Credit Agreement dated as of September 27, 1996, among NCI, the
Restricted Companies, and the vendors party thereto.

                  SECTION 1.02. Terms Generally. The definitions of terms
herein shall apply equally to the singular and plural forms of the terms
defined. Whenever the context may require, any pronoun shall include the
corresponding masculine, feminine and neuter forms. The words "include",
"includes" and "including" shall be deemed to be followed by the phrase
"without limitation". The word "will" shall be construed to have the same
meaning and effect as the word "shall". Unless the context requires otherwise
(a) any definition of or reference to any agreement, instrument or other
document herein shall be construed as referring to such agreement, instrument
or other document as from time to time amended, supplemented or otherwise
modified (subject to any restrictions on such amendments, supplements or
modifications set forth herein), (b) any reference herein to any Person shall
be construed to include such Person's successors and assigns, (c) the words
"herein", "hereof" and "hereunder", and words of similar import, shall be
construed to refer to this Agreement in its entirety and not to any particular
provision hereof, (d) all references herein to Articles, Sections and Exhibits
shall be construed to refer to Articles and Sections of, and Exhibits to, this
Agreement and (e) the words "asset" and "property" shall be construed to have
the same meaning and effect and to refer to any and all tangible and intangible
assets and properties, including cash, securities, accounts and contract
rights.




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                                     - 7 -



                                   ARTICLE II

              The Collateral Agent; Appointment by Vendor Lenders

                  Each Vendor Lender hereby irrevocably appoints the Collateral
Agent as its agent and authorizes the Collateral Agent to take such actions on
its behalf and to exercise such powers as are delegated to the Collateral Agent
by the terms of this Agreement and the other Security Documents, together with
such actions and powers as are reasonably incidental thereto.

                  The Chase Manhattan Bank shall have the same rights and
powers in its capacity as a Lender under the Credit Agreement as any other
Lender and may exercise the same as though it were not the Collateral Agent,
and The Chase Manhattan Bank and its Affiliates may accept deposits from, lend
money to and generally engage in any kind of business with any Credit Party or
any subsidiary or other Affiliate of any thereof as if it were not the
Collateral Agent hereunder.

                  The Collateral Agent shall not have any duties or obligations
except those expressly set forth in this Agreement, the existing intercreditor
agreement and the other Security Documents. Without limiting the generality of
the foregoing, (a) the Collateral Agent shall not be subject to any fiduciary
or other implied duties, regardless of whether a Default has occurred and is
continuing, (b) the Collateral Agent shall not have any duty to take any
discretionary action or exercise any discretionary powers, except discretionary
rights and powers expressly contemplated by this Agreement and the other
Security Documents that the Collateral Agent is required to exercise in writing
by the Required Secured Parties, and (c) except as expressly set forth herein
and in the other Security Documents, the Collateral Agent shall not have any
duty to disclose, and shall not be liable for the failure to disclose, any
information relating to any Credit Party or any of their respective
subsidiaries that is communicated to or obtained by The Chase Manhattan Bank or
any of its Affiliates in any capacity. The Collateral Agent shall not be liable
for any action taken or not taken by it with the consent or at the request of
the Required Secured Parties, or in the absence of its own gross negligence or
wilful misconduct. The Collateral Agent shall not be deemed to have knowledge
of any Default unless and until written notice thereof is given to the
Collateral Agent by the Borrower, a Secured Party or the Administrative Agent,
and the Collateral Agent shall not be responsible for or have any duty to
ascertain or inquire into (i) any statement, warranty or representation made in
or in connection with this Agreement or the other Security Documents, (ii) the
contents of any certificate, report or other document delivered hereunder or
under any of the other Security Documents or in connection herewith of
therewith, (iii) the performance or observance of any of the covenants,
agreements or other terms or conditions set forth herein or in any other
Security Document, (iv) the


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   45

                                     - 8 -


validity, enforceability, effectiveness or genuineness of this Agreement, the
other Security Documents or any other agreement, instrument or document, or (v)
the satisfaction of any condition set forth in Article V of the respective Loan
Agreements or the Second Secured Vendor Financing Agreement.

                  The Collateral Agent shall not, except to the extent
expressly instructed by the Required Secured Parties with respect to collateral
security under the Security Documents, be required to initiate or conduct any
litigation or collection proceedings hereunder, under any Second Secured Loan
Document.

                  The Collateral Agent shall be entitled to rely upon, and
shall not incur any liability for relying upon, any notice, request,
certificate, consent, statement, instrument, document or other writing believed
by it to be genuine and to have been signed or sent by the proper Person. The
Collateral Agent also may rely upon any statement made to it orally or by
telephone and believed by it to be made by the proper Person, and shall not
incur any liability for relying thereon. The Collateral Agent may consult with
legal counsel (who may be counsel for the Borrower), independent accountants
and other experts selected by it, and shall not be liable for any action taken
or not taken by it in accordance with the advice of any such counsel,
accountants or experts.

                  The Collateral Agent may perform any and all of its duties,
and exercise its rights and powers, by or through any one or more sub-agents
appointed by the Collateral Agent. The Collateral Agent and any such sub-agent
may perform any and all of its duties and exercise its rights and powers
through their respective Related Parties. The exculpatory provisions of the
preceding paragraphs shall apply to any such sub-agent and to the Related
Parties of the Collateral Agent and any such sub-agent, and shall apply to
their respective activities in connection with the syndication of the credit
facilities provided for in the Credit Agreement as well as activities as the
Collateral Agent.

                  Subject to the appointment and acceptance of a successor
Collateral Agent as provided in this paragraph, the Collateral Agent may resign
at any time by notifying the Secured Parties, the Borrower and the
Administrative Agent. Upon any such resignation, the Required Secured Parties
shall have the right, in consultation with the Borrower, to appoint, in
consultation with the Borrower, a successor Collateral Agent. If no successor
shall have been so appointed and shall have accepted such appointment within 30
days after such retiring Collateral Agent gives notice of its resignation, then
such retiring Collateral Agent may, on behalf of the Secured Parties, appoint a
successor Collateral Agent, which shall be a bank with an office in New York,
New York, or an Affiliate of any such bank. Upon the acceptance of its
appointment as Collateral Agent by a successor, such successor shall succeed to
and become vested with all the rights, powers, privileges and duties of the
retiring


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   46



                                     - 9 -



Collateral Agent, and the retiring Collateral Agent shall be discharged from
its duties and obligations hereunder and under the other Security Documents.
The fees payable by the Borrower to a successor Collateral Agent shall be the
same as those payable to its predecessor unless otherwise agreed between the
Borrower and such successor. After a Collateral Agent's resignation hereunder,
the provisions of this Article and Section 7.03 of the Restricted Company
Guarantee and Security Agreement shall continue in effect for its benefit in
respect of any actions taken or omitted to be taken by it while it was acting
as Collateral Agent.

                  Each Vendor Lender acknowledges that it has, independently
and without reliance upon the Collateral Agent, or any other Secured Party and
based on such documents and information as it has deemed appropriate, made its
own credit analysis and decision to enter into the Second Secured Vendor
Financing Agreement. Each Vendor Lender also acknowledges that it will,
independently and without reliance upon the Collateral Agent or any other
Secured Party and based on such documents and information as it shall from time
to time deem appropriate, continue to make its own decisions in taking or not
taking action under or based upon this Agreement and the other Security
Documents, any related agreement or any document furnished hereunder or
thereunder.


                                  ARTICLE III

                            Intentionally Left Blank

                  This Article III has been intentionally left blank.


                                   ARTICLE IV

                               Priority of Liens

                  It is the intent of the parties hereto that the Liens created
pursuant to the Security Documents in favor of the Collateral Agent, insofar as
the same shall secure the Second Secured Obligations, shall be second in
ranking to the Liens created pursuant to the Security Documents in favor of the
Collateral Agent, insofar as the same shall secure the Senior Secured
Obligations. Accordingly, anything in any of the Second Secured Loan Documents,
or any other agreement or instrument between any of the Restricted Companies
and any of the Secured Parties to the contrary notwithstanding:



          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   47



                                     - 10 -



                  (a) Each Vendor Lender, in its capacity as a Vendor Lender
         under the Second Secured Vendor Financing Agreement and solely with
         reference thereto, hereby assigns to the Collateral Agent any Liens
         upon any property of any of the Restricted Companies that it may now
         hold or which may hereafter arise by operation of law or otherwise
         (excluding, however, any such Lien arising pursuant to the Security
         Documents); and

                  (b) Each Vendor Lender hereby agrees with the Collateral
         Agent for the benefit of the Collateral Agent and the "Lenders" and
         the "Vendors" under the Loan Agreements that the only Liens securing
         obligations of any of the Restricted Companies to the Vendor Lenders
         under the Second Secured Loan Documents shall be the Liens arising
         under the Security Documents, and that the obligations of the
         Restricted Companies under the Vendor Equipment Agreements shall not
         be entitled to the benefits of any Liens; and

Notwithstanding the foregoing, it is understood that none of the Vendor Lenders
is waiving, renouncing or sharing the benefit of any rights of reclamation or
other remedies accorded a manufacturer, supplier or distributor it may have
under State law, common law or otherwise arising out of the sale of equipment
or other goods by such Vendor Lender to the Restricted Companies.

                  Each Vendor Lender hereby agrees that, to the extent such
Vendor Lender is a party to either of the Loan Agreements, that such Vendor
Lender will exercise any right of set-off or counterclaim first with respect to
the obligations of the Restricted Companies under such Loan Agreement (the
proceeds of which exercise shall therefor be subject to the provisions of
Section 2.16(d) of such Loan Agreement) before exercising any such right with
respect to the obligations of the Restricted Companies under the Second Secured
Vendor Financing Agreement.

                  It is the intent of the parties hereto that the Vendor
Lenders shall not have any right to require the Collateral Agent to exercise
any of the rights and remedies available to it with respect to the Second
Secured Obligations until after the Senior Termination Date, or to refrain from
the exercise of any of the rights and remedies available to it with respect to
the Senior Secured Obligations prior to the Senior Termination Date and not to
(A) oppose any request for relief with respect to the Collateral during the
pendency of any bankruptcy or insolvency proceeding and (B) request any relief
with respect to the Collateral during the pendency of any such proceeding
without the prior consent of the Required Secured Parties. Without limiting the
generality of the foregoing, if any of the Restricted Companies shall become
subject to a proceeding under the United States Bankruptcy Code and if as
debtor(s)-in-possession move for approval of financing to be provided in good
faith by the Lenders or


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   48

                                     - 11 -



Vendors under Section 364 of the United States Bankruptcy Code, or the use of
cash collateral with the consent of the Lenders or Vendors under Section 363 of
the United States Bankruptcy Code, each of the Vendor Lenders hereby agrees
that as follows:

                         (i) adequate notice by the Lenders and Vendors shall
         have been provided for such financing or use of cash collateral if the
         Vendor Lenders receive notice three (3) business days prior to the
         entry of the order approving (and at least one (1) business day prior
         to the hearing on) such financing or use of cash collateral and

                        (ii) no objection will be raised by the Vendor Lenders
         to any such financing on the grounds of a failure to provide "adequate
         protection" for the Liens of the Collateral Agent insofar as securing
         the Second Secured Obligations or as a result of any of the terms of
         such financing so long as (A) the interest rate, fees, advance rates,
         lending sublimits and limits and other terms are commercially
         reasonable under the circumstances and (B) the Collateral Agent
         retains a Lien on the Collateral for the benefit of the Second Secured
         Obligations (including proceeds thereof arising after the commencement
         of such proceeding) with the same priority as existed prior to the
         commencement of the proceeding under the United States Bankruptcy
         Code.

                  Notwithstanding the preceding paragraph, the provisions of
clauses (i) and (ii) above shall not be applicable to (a) Motorola or (b) any
Vendor Lender who is simultaneously either a "Lender" under the Credit
Agreement or a "Vendor" under the Vendor Financing Agreement so long as such
Vendor Lender continues to be a "Lender" or a "Vendor" under such Loan
Agreements, and provided further that any Loans held by such Vendor Lender
pursuant to the Loan Agreements shall have been held for at least 180 days
prior to the commencement of any bankruptcy or insolvency proceeding. Nothing
in the preceding sentence is intended to override the provisions of the
Security Documents that at least 51% or all, as the case may be, of the Vendor
Lenders are necessary to require the Collateral Agent to take or refrain from
taking any action under the Security Documents. Nothing contained herein shall
be deemed to limit the rights of any Vendor Lender to object to post-petition
financing or use of cash collateral not covered by the preceding paragraph.




          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   49

                                     - 12 -

                                   ARTICLE V

                                 Miscellaneous


                  SECTION 5.01. Notices. All notices and other communications
provided for herein shall be in writing and shall be delivered by hand or
overnight courier service, mailed by certified or registered mail or sent by
telecopy, as follows:

                  (a) if to the Borrower, to it at 1505 Farm Credit Drive,
         Suite 100, McLean, Virginia 22102, Attention Steven Shindler, Senior
         Vice President and Chief Financial Officer (Telecopy No.
         703-394-3011);

                  (b) if to any Restricted Company other than the Borrower, to
         such Restricted Company care of the Borrower at the address for
         notices indicated in clause (a) above;

                  (c) if to Motorola, to it at 1301 East Algonquin Road,
         Schaumburg, Illinois 60196, Attention Vice President, Director of
         Financing (Telecopy No. 847-538-2491), with a copy to Gary Tatje at
         such address and to the General Counsel and Secretary at 1303 East
         Algonquin Road, Schaumburg, Illinois 60196;

                  (d) if to any Vendor Lender other than Motorola, to it at
         such address as shall be specified by such Vendor Lender at the time
         such Vendor Lender is deemed to become a party hereto as contemplated
         in Section 5.04 hereof; and

                  (e) if to the Collateral Agent, to it at 270 Park Avenue,
         37th Floor, New York, New York 10017, Attention Tracey Navin,
         (Telecopy No. 212-270-4164).

Any party hereto may change its address or telecopy number for notices and
other communications hereunder by notice to the other parties hereto. All
notices and other communications given to any party hereto in accordance with
the provisions of this Agreement shall be deemed to have been given on the date
of receipt.

                  SECTION 5.02.  Waivers; Amendments.

                  (a) No failure or delay by the Collateral Agent or any
Secured Party in exercising any right or power hereunder shall operate as a
waiver thereof, nor shall any single or partial exercise of any such right or
power, or any abandonment or discontinuance of steps to enforce such a right or
power, preclude any other or further exercise thereof or the exercise of any
other right or power. The rights and remedies of the Collateral Agent



          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   50

                                     - 13 -


and the Secured Parties hereunder are cumulative and are not exclusive of any
rights or remedies that they would otherwise have. No waiver of any provision
of this Agreement or consent to any departure by any party therefrom shall in
any event be effective unless the same shall be permitted by paragraph (b) of
this Section 5.02, and then such waiver or consent shall be effective only in
the specific instance and for the purpose for which given.

                  (b) Neither this Agreement nor any provision hereof may be
waived, amended or modified except pursuant to an agreement or agreements in
writing entered into by the Restricted Companies, the Required Vendor Lenders
and the Collateral Agent.

                  (c) No Security Document (other than this Agreement, as to
which paragraph (b) above shall control) nor any provision thereof may be
waived, amended or modified except pursuant to an agreement or agreements in
writing entered into by the Restricted Companies party thereto, and by the
Collateral Agent with the consent of the Required Secured Parties; provided
that, (i) without the written consent of each Secured Party, no such agreement
shall release any Restricted Company from its obligations under any Security
Document and (ii) without the written consent of each Secured Party, no such
agreement shall release any collateral or otherwise terminate any Lien under
any Security Document, agree to additional obligations being secured by such
collateral security (unless either (x) the Lien for such additional obligations
shall be junior to the Lien in favor of the Second Secured Obligations secured
by such Security Document, in which event the Collateral Agent may consent to
such junior Lien provided that it obtains the consent of the Required Secured
Parties thereto or (y) such additional obligations arise as a result of the
incurrence of the "Additional Vendor Loans" (as defined in the Second Secured
Vendor Financing Agreement), in which event the Collateral Agent may consent to
such additional obligations being secured by such collateral, without the
consent of the Vendor Lenders under the Second Secured Vendor Financing
Agreement), alter the relative priorities of the obligations entitled to the
benefits of the Liens created under the Security Documents or release any
Guarantor under the Restricted Company Guarantee and Security Agreement from
its guarantee obligations thereunder, except that no such consent shall be
required, and the Collateral Agent is hereby authorized, to release any Lien
covering property (and to release any such Guarantor) that is the subject of
either a disposition of property permitted under the Loan Agreements and the
Second Secured Vendor Financing Agreement or a disposition to which the
"Required Lenders", "Required Vendors" and "Required Vendor Lenders" under the
Loan Agreements and the Second Secured Vendor Financing Agreement have
consented; provided further that no such agreement shall amend, modify or
otherwise affect the rights or duties of the Collateral Agent without the prior
written consent of the Collateral Agent.

                  SECTION 5.03. Indemnification. To the extent that the Credit
Parties fail to pay any amount required to be paid by them to the Collateral
Agent under Section 7.03(a) of the Restricted Company Guarantee and Security
Agreement that arises after the Senior Termination Date, each Vendor Lender
severally agrees to pay to the Collateral Agent such Vendor Lender's Applicable
Percentage (determined as of the time that the applicable unreimbursed expense
or indemnity payment is sought) of such unpaid amount; provided that


         Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   51

                                     - 14 -



the unreimbursed expense or indemnified loss, claim, damage, liability or
related expense, as the case may be, was incurred by or asserted against the
Collateral Agent in its capacity as such.

                  SECTION 5.04. Successors and Assigns. The provisions of this
Agreement shall be binding upon and inure to the benefit of the respective
successors and assigns of the Restricted Companies, the Collateral Agent, the
Secured Parties and each holder of the Secured Obligations. Nothing in this
Agreement, expressed or implied, shall be construed to confer upon any Person
(other than the parties hereto, the Secured Parties and the respective
successors and assigns of the Restricted Companies, the Collateral Agent, the
Secured Parties and each holder of the Secured Obligations) any legal or
equitable right, remedy or claim under or by reason of this Agreement.

                  As provided in Section 10.04(b) of the Second Secured Vendor
Financing Agreement, upon any assignment by any Vendor Lender of any interest
in the "Tranche D Loans" or "Tranche D Commitment" under the Second Secured
Vendor Financing Agreement held by it, the respective assignee shall be deemed
to have become a party to this Agreement (and thereby to have consented to be
bound by, and subject to the provisions of, this Agreement).

                  SECTION 5.05. Counterparts. This Agreement may be executed in
counterparts (and by the parties hereto on different counterparts), each of
which shall constitute an original, but all of which when taken together shall
constitute a single contract.

                  SECTION 5.06. Severability. Any provision of this Agreement
held to be invalid, illegal or unenforceable in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such invalidity, illegality
or unenforceability without affecting the validity, legality and enforceability
of the remaining provisions hereof; and the invalidity of a particular
provision in a particular jurisdiction shall not invalidate such provision in
any other jurisdiction.

                  SECTION 5.07.  Governing Law.  This Agreement shall be
construed in accordance with and governed by the law of the State of New York.

                  SECTION 5.08. Headings. Article and Section headings used
herein are for convenience of reference only, are not part of this Agreement
and shall not affect the construction of, or be taken into consideration in
interpreting, this Agreement.


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   52

                                     - 15 -



                  IN WITNESS WHEREOF, the parties hereto have caused this
Second Secured Intercreditor and Collateral Agency Agreement to be duly
executed by their respective authorized officers as of the day and year first
above written.


                              RESTRICTED COMPANIES

                                 NEXTEL FINANCE COMPANY (successor to
                                  Fleet Call Corporation),

                                  By
                                    --------------------------------------
                                    Name:
                                    Title:

                                 ADVANCED MOBILECOMM OF
                                  NORTH CAROLINA, INC.
                                 AIRLINK COMMUNICATIONS, INC.
                                  (successor to TRS, Inc.)
                                 AMERICAN MOBILE SYSTEMS,
                                  INCORPORATED (successor to Saber
                                  Communications, Inc.)
                                 DIAL CALL, INC.
                                 DIAL DISTANCE, INC.
                                 FC NEW YORK, INC. (successor to Metrocom
                                  Trunked Radio Communication Systems, Inc.)
                                 FCI 900, INC.
                                 FLEET CALL OF TEXAS, INC. (successor to
                                  FM Tower Company, Metrolink
                                  Communications Corporation and National
                                  Tower Trunking Systems, Inc.)
                                 NEXTEL COMMUNICATIONS OF THE
                                  MID-ATLANTIC, INC. (successor to Dispatch
                                  Communications of Maryland, Inc., Dispatch
                                  Communications of Minnesota, Inc., Dispatch
                                  Communications of New England, Inc.,
                                  Dispatch Communications of Pennsylvania,Inc.)
                                 NEXTEL LICENSE HOLDINGS 1, INC.
                                 NEXTEL LICENSE HOLDINGS 2, INC.
                                  (successor to Comqor, Inc.)


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   53

                                     - 16 -



                                 NEXTEL LICENSE HOLDINGS 3, INC.
                                   (successor to Dial Call Arkansas, Inc.,
                                   Custom Radio/Johnson Communications, Inc.,
                                   Dial Call Florida, Inc., Dial Call
                                   Kentucky, Inc., Dial Call Louisiana, Inc.,
                                   Dial Call Texas, Inc., Dial Call           
                                   Virginia, Inc., Dial Call West Virginia, Inc.
                                   and U.S. Digital, Inc.)     
                                 NEXTEL LICENSE HOLDINGS 4, INC.   
                                 NEXTEL OF TEXAS, INC. (successor to Fort  
                                   Worth Communications, Inc.)             
                                 NEXTEL WEST CORP.                 
                                   (successor to Airwave Communications Corp.
                                   (Seattle), C-Call Corporation, Dispatch   
                                   Communications of Arizona, Inc., ESMR Sub,
                                   Inc., Fleet Call of Utah, Inc., Fleet Call
                                   West, Inc., Mijac Enterprises, Inc., Mobile
                                   Radio of Illinois, Inc., Motorola SF, Inc.,
                                   Nextel Hawaii Acquisition Corp.,           
                                   Nextel Utah Acquisition Corp., Nextel      
                                   Western Acquisition Corp., OneComm         
                                 Corporation, N.A., Powerfone                 
                                   Holdings, Inc., Powerfone, Inc.,           
                                   Smart SMR of Illinois, Inc., Shoreland     
                                   Communications, Inc. and Spectrum Resources
                                   of the Midwest, Inc.)                      
                                 SAFETY NET, INC.                             
                                 SMART SMR, INC.                              
                                 SMART SMR OF CALIFORNIA, INC.                
                                 SMART SMR OF NEW YORK, INC.                  
                                 
                                  By
                                    ---------------------------------------
                                    Name:
                                    Title:



          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   54

                                    - 17 -


                                      FORT WORTH TRUNKED RADIO
                                       LIMITED PARTNERSHIP

                                      By Nextel of Texas,
                                         a General Partner


                                        By
                                           ----------------------
                                           Name:
                                           Title:


                                    MOTOROLA

                                    MOTOROLA, INC.

                                     By
                                         ------------------
                                         Name:
                                         Title:

                                COLLATERAL AGENT

                                 THE CHASE MANHATTAN BANK, as
                                  Collateral Agent

                                  By
                                     ----------------------
                                     Name:
                                     Title:


          Second Secured Intercreditor and Collateral Agency Agreement


<PAGE>   1
                                                                [Execution Copy]




 ==============================================================================



                  SECOND SECURED VENDOR FINANCING AGREEMENT


                                 dated as of


                               August 29, 1997


                                    among


                        NEXTEL COMMUNICATIONS, INC.,


                           NEXTEL FINANCE COMPANY

                                     and

               THE OTHER "RESTRICTED COMPANIES" PARTY HERETO,

                                     and

                       THE VENDOR LENDERS PARTY HERETO






 ==============================================================================
<PAGE>   2
                               TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                         Page
<S>                                                                                                        <C>
                                                              ARTICLE I

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
         SECTION 1.01.  Defined Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
         SECTION 1.02.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         SECTION 1.03.  Terms Generally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         SECTION 1.04.  Accounting Terms; GAAP  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
         SECTION 1.05.  Tax Sharing Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22

                                                              ARTICLE II

The Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
         SECTION 2.01.  The Tranche D Commitments . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
         SECTION 2.02.  Tranche D Loans and Borrowings  . . . . . . . . . . . . . . . . . . . . . . . . .  23
         SECTION 2.03.  Requests for Borrowings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         SECTION 2.04.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         SECTION 2.05.  Funding of Borrowings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         SECTION 2.06.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         SECTION 2.07.  Termination and Reduction of Tranche D Commitments  . . . . . . . . . . . . . . .  23
         SECTION 2.08.  Repayment of Tranche D Loans; Evidence of Debt  . . . . . . . . . . . . . . . . .  24
         SECTION 2.09.  Prepayment of Tranche D Loans . . . . . . . . . . . . . . . . . . . . . . . . . .  25
         SECTION 2.10.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         SECTION 2.11.  Interest  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         SECTION 2.12.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         SECTION 2.13.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         SECTION 2.14.  Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         SECTION 2.15.  Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         SECTION 2.16.  Payments Generally  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30

                                                             ARTICLE III

Guarantee by NCI  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
         Section 3.01.  The Guarantee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
         Section 3.02.  Obligations Unconditional . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
         Section 3.03.  Reinstatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
         Section 3.04.  Subrogation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         Section 3.05.  Remedies  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         Section 3.06.  Instrument for the Payment of Money . . . . . . . . . . . . . . . . . . . . . . .  33
         Section 3.07.  Continuing Guarantee  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
</TABLE>





                                      (i)
<PAGE>   3


<TABLE>
<CAPTION>
                                                                                                         Page
                                                                                                         ----
<S>                                                                                                        <C>
                                                              ARTICLE IV

Representations and Warranties  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         SECTION 4.01.  Organization; Powers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         SECTION 4.02.  Authorization; Enforceability . . . . . . . . . . . . . . . . . . . . . . . . . .  34
         SECTION 4.03.  Governmental Approvals; No Conflicts  . . . . . . . . . . . . . . . . . . . . . .  34
         SECTION 4.04.  Financial Condition; No Material Adverse Change . . . . . . . . . . . . . . . . .  34
         SECTION 4.05.  Representations in Vendor Financing Agreement . . . . . . . . . . . . . . . . . .  35

                                                              ARTICLE V

Conditions  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         SECTION 5.01.  Effective Date  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         SECTION 5.02.  Each Tranche D Loan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  37

                                                              ARTICLE VI

Affirmative Covenants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
         SECTION 6.01.  Financial Statements and Other Information  . . . . . . . . . . . . . . . . . . .  38
         SECTION 6.02.  Notices of Material Events  . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         SECTION 6.03.  Existence; Conduct of Business  . . . . . . . . . . . . . . . . . . . . . . . . .  41
         SECTION 6.04.  Payment of Obligations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
         SECTION 6.05.  Maintenance of Properties; Insurance  . . . . . . . . . . . . . . . . . . . . . .  42
         SECTION 6.06.  Books and Records; Inspection Rights  . . . . . . . . . . . . . . . . . . . . . .  43
         SECTION 6.07.  Fiscal Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         SECTION 6.08.  Compliance with Laws  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         SECTION 6.09.  Use of Proceeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         SECTION 6.10.  Hedging Agreements  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         SECTION 6.11.  Certain Obligations Respecting Subsidiaries and Collateral Security . . . . . . .  44
         SECTION 6.12.  Planned Option Issuances  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46

                                                             ARTICLE VII

Negative Covenants  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         SECTION 7.01.  Indebtedness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         SECTION 7.02.  Liens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
         SECTION 7.03.  Fundamental Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
         SECTION 7.04.  Investments, Loans, Advances, Guarantees and Acquisitions; Hedging Agreements . .  52
</TABLE>





                                      (ii)
<PAGE>   4


<TABLE>
<CAPTION>
                                                                                                         Page
                                                                                                         ----
<S>                                                                                                        <C>
         SECTION 7.05.  Restricted Payments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
         SECTION 7.06.  Transactions with Affiliates  . . . . . . . . . . . . . . . . . . . . . . . . . .  57
         SECTION 7.07.  Restrictive Agreements  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
         SECTION 7.08.  Certain Financial and Other Covenants . . . . . . . . . . . . . . . . . . . . . .  58
         SECTION 7.09.  Lines of Business, Etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  62
         SECTION 7.10.  Modifications to Certain Agreements . . . . . . . . . . . . . . . . . . . . . . .  62

                                                             ARTICLE VIII

Events of Default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  62

                                                              ARTICLE IX

Intentionally Left Blank  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  66

                                                              ARTICLE X

Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  66
         SECTION 10.01.  Notices  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  66
         SECTION 10.02.  Waivers; Amendments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  67
         SECTION 10.03.  Expenses; Indemnity; Damage Waiver . . . . . . . . . . . . . . . . . . . . . . .  68
         SECTION 10.04.  Successors and Assigns . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  70
         SECTION 10.05.  Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  72
         SECTION 10.06.  Counterparts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  73
         SECTION 10.07.  Severability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  73
         SECTION 10.08.  Right of Setoff  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  73
         SECTION 10.09.  Governing Law; Jurisdiction; Consent to Service of Process . . . . . . . . . . .  73
         SECTION 10.10.  WAIVER OF JURY TRIAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  74
         SECTION 10.11.  Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  74
         SECTION 10.12.  Confidentiality  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  75
         SECTION 10.13.  Intentionally Left Blank . . . . . . . . . . . . . . . . . . . . . . . . . . . .  75
         SECTION 10.14.  Obligations Senior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  75
</TABLE>


EXHIBITS:

Exhibit A   -- [Intentionally Left Blank]
Exhibit B   -- [Intentionally Left Blank]
Exhibit C-1 -- Copy of Restricted Company Guarantee and
                            Security Agreement





                                     (iii)
<PAGE>   5
Exhibit C-2 -- Copy of Amendment No. 1 to Restricted Company
                            Guarantee and Security Agreement
Exhibit C-3 -- Form of Amendment No. 2 to Restricted Company
                            Guarantee and Security Agreement
Exhibit D   -- Form of Second Secured Intercreditor and Collateral Agency
                            Agreement
Exhibit E   -- Form of Joinder Agreement





                                      (iv)
<PAGE>   6

                 SECOND SECURED VENDOR FINANCING AGREEMENT dated as of August
29, 1997 among NEXTEL COMMUNICATIONS, INC., NEXTEL FINANCE COMPANY and the
other RESTRICTED COMPANIES party hereto, and the VENDOR LENDERS party hereto.

                 The parties hereto agree as follows:


                                   ARTICLE I

                                  Definitions

                 SECTION 1.01.  Defined Terms.  As used in this Agreement, the
following terms have the meanings specified below:

                 "Administrative Agent" means Toronto Dominion (Texas) Inc., in
its capacity as administrative agent for the Lenders under the Credit
Agreement.

                 "Affiliate" means, with respect to a specified Person, another
Person that directly, or indirectly through one or more intermediaries,
Controls or is Controlled by or is under common Control with the Person
specified.

                 "Agents" means the Administrative Agent and the Collateral
Agent.

                 "Amendment No. 3 Effective Date" means the date on which the
conditions to the effectiveness of the amendments provided for in Amendment No.
3 of the Vendor Financing Agreement set forth in Section 6 thereof are
satisfied (or waived in accordance with said Section 6).

                 "Annualized Operating Cash Flow" means, as at any day,
Operating Cash Flow for the fiscal quarter ending on or most recently ended
prior to such day multiplied by 4.

                 "Annualized Revenue" means, as at any day, gross revenues of
the Restricted Companies (determined on a combined basis without duplication in
accordance with GAAP) for the period of three complete calendar months ending
on, or most recently ended prior to, such day multiplied by 4.

                 "Authorizations" means all validations, exemptions,
franchises, waivers, approvals, orders or authorizations, consents, licenses,
certificates and permits from, the FCC, any PUC and any other Federal, state or
local regulatory or governmental bodies and authorities, including any
subdivision thereof.





                   Second Secured Vendor Financing Agreement
<PAGE>   7
                                     - 2 -



                 "Availability Period" means the period from and including the
Effective Date to but excluding the earlier of (a) the Tranche D Commitment
Termination Date and (b) the date of termination of the Tranche D Commitments.

                 "Average Life to Maturity" means, as at any day with respect
to any Indebtedness, the quotient obtained by dividing (a) the sum of the
products of (i) the number of years from the day to the date or dates of each
successive principal payment of such Indebtedness multiplied by (ii) the amount
of each such principal payment by (b) the sum of all such principal payments.

                 "Basic Documents" means the Second Secured Loan Documents, the
Credit Agreement, the Vendor Financing Agreement and the Vendor Equipment
Agreements.

                 "Board" means the Board of Governors of the Federal Reserve
System of the United States of America.

                 "Borrower" means Nextel Finance Company, a Delaware
corporation.

                 "Borrowing" means Tranche D Loans made on the same date.

                 "Borrowing Request" means a request by the Borrower for a
Borrowing in accordance with Section 2.03.

                 "Business Day" means any day that is not a Saturday, Sunday or
other day on which commercial banks in New York City are authorized or required
by law to remain closed.

                 "Capital Expenditures" means, for any period, the sum for the
Restricted Companies (or, as the case may be, for NCI and the Restricted
Companies) of the aggregate amount of expenditures (including the aggregate
amount of Capital Lease Obligations incurred during such period) made to
acquire or construct fixed assets, plant and equipment (including renewals,
improvements and replacements, but excluding repairs) during such period
computed in accordance with GAAP.  "Capital Expenditures" for the Restricted
Companies shall be determined on a combined basis, and for NCI and the
Restricted Companies shall be determined on a consolidated basis (excluding the
Unrestricted Companies), in each case without duplication in accordance with
GAAP.

                 "Capital Lease Obligations" of any Person means the
obligations of such Person to pay rent or other amounts under any lease of (or
other arrangement conveying the right to use) real or personal property, or a
combination thereof, which obligations are required to be classified and
accounted for as capital leases on a balance sheet of such Person





                   Second Secured Vendor Financing Agreement
<PAGE>   8
                                     - 3 -



under GAAP, and the amount of such obligations shall be the capitalized amount
thereof determined in accordance with GAAP.

                 "Change in Control" means either (a) a "Change of Control"
under and as defined in the Public Note Indentures, or any other similar event
(howsoever defined) requiring the prepayment, redemption or offer to repurchase
of the respective Indebtedness under any agreement providing for the issuance
of Indebtedness of NCI after September 27, 1996, pursuant to Section 7.01(c)(i)
or 7.01(d), or (b) the termination or material modification of the authority of
the Operations Committee of NCI (including through the occurrence of a "Trigger
Event" as defined in NCI's Certificate of Incorporation as in effect on
September 27, 1996) or the inability of Craig O. McCaw (whether acting directly
or through any Person controlled by him) for any reason (other than by reason
of his death, disability or incompetence) to designate a majority of the
members of said Operations Committee.

                 "Chase" means The Chase Manhattan Bank, a New York state
banking corporation.

                 "Code" means the Internal Revenue Code of 1986, as amended
from time to time.

                 "Collateral" means all cash and other property in which the
Collateral Agent has a Lien (whether or not perfected under applicable law)
under any of the Security Documents, including all "Collateral" under and as
defined in the Restricted Company Guarantee and Security Agreement.

                 "Collateral Agent" means The Chase Manhattan Bank, in its
capacity as collateral agent for the Lenders, the Vendors and the Vendor
Lenders under the Security Documents.

                 "Contributed Capital" means, as at any time, the net aggregate
amount of equity capital received after September 30, 1996 by the Restricted
Companies in respect of shares of common stock to the extent such amount does
not exceed the aggregate proceeds of Qualifying Debt or Equity Issuances by NCI
after September 30, 1996.

                 "Control" means the possession, directly or indirectly, of the
power to direct or cause the direction of the management or policies of a
Person, whether through the ability to exercise voting power, by contract or
otherwise. "Controlling" and "Controlled" have meanings correlative thereto.





                   Second Secured Vendor Financing Agreement
<PAGE>   9
                                     - 4 -



                 "Credit Agreement" means the Credit Agreement dated as of
September 27, 1996 among NCI, the Restricted Companies, the Lenders named
therein, the Administrative Agent and the Collateral Agent.

                 "Credit Parties" means NCI and the Restricted Companies.

                 "Debt Service" means, for any period, the sum for the
Restricted Companies (or, as the case may be, for NCI and the Restricted
Companies) of the following:  (a) the amount, if any, by which the aggregate
principal amount of "Revolving Credit Loans" outstanding under the Credit
Agreement at the beginning of such period shall exceed the aggregate amount of
the "Revolving Credit Commitments" thereunder scheduled to be in effect at the
end of such period after giving effect to any reductions of such Commitments
scheduled to occur during such period pursuant to Section 2.07 of the Credit
Agreement plus (b) the amount, if any, by which the aggregate principal amount
of Tranche B Loans outstanding under the Vendor Financing Agreement at the
beginning of such period shall exceed the aggregate amount of the Tranche B
Commitment under the Vendor Financing Agreement scheduled to be in effect at
the end of such period after giving effect to any reductions of such Commitment
scheduled to occur during such period pursuant to Section 2.07 of the Vendor
Financing Agreement plus (c) all regularly scheduled payments or regularly
scheduled mandatory prepayments of principal of any other Indebtedness
(including the "Tranche A Loans" and "Tranche C Loans" under the Vendor
Financing Agreement, the "Tranche C Term Loans", the "Tranche D Term Loans" and
the "Tranche E Loans" under the Credit Agreement and the principal component of
any payments in respect of Capital Lease Obligations, but excluding any
prepayments made pursuant to Section 2.09) made during such period plus (d) all
Interest Expense for such period.  "Debt Service" for the Restricted Companies
shall be determined on a combined basis, and for NCI and the Restricted
Companies shall be determined on a consolidated basis (excluding the
Unrestricted Companies), in each case without duplication in accordance with
GAAP.

                 "Default" means any event or condition which constitutes an
Event of Default or which upon notice, lapse of time or both would, unless
cured or waived, become an Event of Default.

                 "Disclosed Matters" means the actions, suits and proceedings
and the environmental matters disclosed in Schedule 4.06 to the Vendor
Financing Agreement.

                 "Disposition" means any sale, assignment, transfer or other
disposition of any property (whether now owned or hereafter acquired) by any
Restricted Company to any other Person excluding any sale, assignment, transfer
or other disposition of any property sold or disposed of in the ordinary course
of business and on ordinary business terms.





                   Second Secured Vendor Financing Agreement
<PAGE>   10
                                     - 5 -



                 "Disposition Investment" means, with respect to any
Disposition, any promissory notes or other evidences of indebtedness or
Investments received by the Restricted Companies in connection with such
Disposition.

                 "Effective Date" means the date on which the conditions
specified in Section 5.01 are satisfied (or waived in accordance with Section
10.02).

                 "Enhanced SMR System" means a wide-area network of specialized
mobile radio base stations that employs digital and other advanced, spectrally
efficient communications technologies to provide a full range of communications
services including voice, dispatch, interconnected telephone and data services.

                 "Environmental Laws" means all laws, rules, regulations,
policies, codes, ordinances, orders, decrees, judgments, injunctions, notices
or binding agreements issued, promulgated or entered into by any Governmental
Authority, relating in any way to the environment, preservation or reclamation
of natural resources, the management, release or threatened release of any
Hazardous Material or to health and safety matters, including FCC rules and
policies concerning RF Emissions.

                 "Environmental Liability" means any liability, contingent or
otherwise (including any liability for damages, costs of environmental
remediation, fines, penalties or indemnities), of any Restricted Company
directly or indirectly resulting from or based upon (a) violation of any
Environmental Law, (b) the generation, use, handling, transportation, storage,
treatment or disposal of any Hazardous Materials or RF Emissions, (c) exposure
to any Hazardous Materials or RF Emissions, (d) the release or threatened
release of any Hazardous Materials into the environment or (e) any contract,
agreement or other consensual arrangement pursuant to which liability is
assumed or imposed with respect to any of the foregoing.

                 "Equity Rights" means, with respect to any Person, any
subscriptions, options, warrants, commitments, preemptive rights or agreements
of any kind (including any stockholders' or voting trust agreements) for the
issuance or sale of, or securities convertible into, any additional shares of
capital stock of any class, or partnership or other ownership interests of any
type in, such Person.

                 "ERISA" means the Employee Retirement Income Security Act of
1974, as amended from time to time.

                 "ERISA Affiliate" means any trade or business (whether or not
incorporated) that, together with the Borrower, is treated as a single employer
under Section 414(b) or (c)





                   Second Secured Vendor Financing Agreement
<PAGE>   11
                                     - 6 -



of the Code or, solely for purposes of Section 302 of ERISA and Section 412 of
the Code, is treated as a single employer under Section 414 of the Code.

                 "ERISA Event" means (a) any "reportable event", as defined in
Section 4043 of ERISA or the regulations issued thereunder with respect to a
Plan (other than an event for which the 30-day notice period is waived), (b)
the existence with respect to any Plan of an "accumulated funding deficiency"
(as defined in Section 412 of the Code or Section 302 of ERISA), whether or not
waived, (c) the filing pursuant to Section 412(d) of the Code or Section 303(d)
of ERISA of an application for a waiver of the minimum funding standard with
respect to any Plan, (d) the incurrence by the Borrower or any of its ERISA
Affiliates of any liability under Title IV of ERISA with respect to the
termination of any Plan, (e) the receipt by the Borrower or any ERISA Affiliate
from the PBGC or a plan administrator of any notice relating to an intention to
terminate any Plan or Plans or to appoint a trustee to administer any Plan, (f)
the incurrence by the Borrower or any of its ERISA Affiliates of any liability
with respect to the withdrawal or partial withdrawal from any Plan or
Multiemployer Plan, or (g) the receipt by the Borrower or any ERISA Affiliate
of any notice, or the receipt by any Multiemployer Plan from the Borrower or
any ERISA Affiliate of any notice, concerning the imposition of Withdrawal
Liability or a determination that a Multiemployer Plan is, or is expected to
be, insolvent or in reorganization, within the meaning of Title IV of ERISA.

                 "Event of Default" has the meaning assigned to such term in
Article VIII. 

                 "Excess Cash Flow" means, for any fiscal year of the
Restricted Companies, the excess of (a) Operating Cash Flow for such fiscal
year over (b) the sum of (i) Debt Service for the Restricted Companies for such
fiscal year plus (ii) the aggregate amount of all Capital Expenditures for the
Restricted Companies made during such fiscal year, except for any such Capital
Expenditures to the extent financed with the proceeds of Indebtedness incurred
pursuant to Section 7.01(g) during such fiscal year and that is secured by
Liens permitted under Section 7.02(f) plus (iii) the aggregate amount paid, or
required to be paid, in cash in respect of income taxes during such fiscal year
plus (iv) $5,000,000.

                 "Excluded Taxes" means, with respect to any Vendor Lender, or
any other recipient of any payment to be made by or on account of any
obligation of the Borrower hereunder, (a) income, net worth or franchise taxes
imposed on (or measured by) its net income or net worth by the United States of
America, or by the jurisdiction under the laws of which such recipient is
organized or in which its principal office is located or (b) any branch profits
taxes imposed by the United States of America or any similar tax imposed by any
other jurisdiction in which the Borrower is located.





                   Second Secured Vendor Financing Agreement
<PAGE>   12
                                     - 7 -



                 "FCC" means the Federal Communications Commission or any
Governmental Authority substituted therefor.

                 "FCC License" means any paging, mobile telephone, specialized
mobile radio, microwave or other license, permit, consent, certificate of
compliance, franchise, approval, waiver or authorization granted or issued by
the FCC, including any of the foregoing authorizing or permitting the
acquisition, construction or operation of an SMR System, radio paging system,
mobile telephone system or other radio communications system.

                 "Final Order" means an action by any Governmental Authority
that has not been reversed, stayed, enjoined, set aside, annulled, or
suspended, and with respect to which no requests are pending for administrative
or judicial review, reconsideration, appeal, or stay, and the time for filing
any such requests and the time for such Governmental Authority to set aside the
action on its own motion have expired.

                 "Financial Officer" means, with respect to NCI or the
Borrower, the chief financial officer, principal accounting officer, treasurer
or controller of NCI or the Borrower, as the case may be.

                 "First Tier Restricted Company" means any Restricted Company
that is not a Wholly Owned Subsidiary of one or more other Restricted
Companies.

                 "Fixed Charges Ratio" means, as at the last day of any fiscal
quarter, the ratio of (a) the sum of (i) Annualized Operating Cash Flow as at
such day plus (ii) the aggregate unutilized amount of the "Commitments" under
the Credit Agreement and the unutilized amount of the "Commitments" under the
Vendor Financing Agreement, as at such day plus (iii) the amount of cash and
cash equivalents held by NCI and the Restricted Companies on such day to (b)
the sum of (i) Debt Service for NCI and the Restricted Companies for the period
of four fiscal quarters ending on such day plus (ii) the aggregate amount of
Capital Expenditures for NCI and the Restricted Companies made during such
period, except for any such Capital Expenditures to the extent financed with
the proceeds of Indebtedness incurred pursuant to Section 7.01(g) during such
fiscal year and that is secured by Liens permitted under Section 7.02(f) plus
(iii) the aggregate amount of Federal, state and local income taxes paid by NCI
and its subsidiaries in respect of such period.

                 "GAAP" means generally accepted accounting principles in the
United States of America.

                 "Governmental Authority" means the government of the United
States of America, any other nation or any political subdivision thereof,
whether state or local, and any agency, authority, instrumentality, regulatory
body, court, central bank or other entity





                   Second Secured Vendor Financing Agreement
<PAGE>   13
                                     - 8 -



exercising executive, legislative, judicial, taxing, regulatory or
administrative powers or functions of or pertaining to government.

                 "Guarantee" of or by any Person (the "guarantor") means any
obligation, contingent or otherwise, of the guarantor guaranteeing or having
the economic effect of guaranteeing any Indebtedness or other obligation of any
other Person (the "primary obligor") in any manner, whether directly or
indirectly, and including any obligation of the guarantor, direct or indirect,
(a) to purchase or pay (or advance or supply funds for the purchase or payment
of) such Indebtedness or other obligation or to purchase (or to advance or
supply funds for the purchase of) any security for the payment thereof, (b) to
purchase or lease property, securities or services for the purpose of assuring
the owner of such Indebtedness or other obligation of the payment thereof, (c)
to maintain working capital, equity capital or any other financial statement
condition or liquidity of the primary obligor so as to enable the primary
obligor to pay such Indebtedness or other obligation or (d) as an account party
in respect of any letter of credit or letter of guaranty issued to support such
Indebtedness or obligation; provided, that the term Guarantee shall not include
endorsements for collection or deposit in the ordinary course of business.

                 "Hazardous Materials" means all explosive or radioactive
substances or wastes and all hazardous or toxic substances, wastes or other
pollutants, including petroleum or petroleum distillates, asbestos or asbestos
containing materials, polychlorinated biphenyls, radon gas, infectious or
medical wastes and all other substances or wastes of any nature regulated
pursuant to any Environmental Law.

                 "Hedging Agreement" means any interest rate protection
agreement, foreign currency exchange agreement, commodity price protection
agreement or other interest or currency exchange rate or commodity price
hedging arrangement.

                 "Indebtedness" of any Person means, without duplication, (a)
all obligations of such Person for borrowed money (whether by loan, the
issuance and sale of debt securities or the sale of property to another Person
subject to an understanding or agreement, contingent or otherwise, to
repurchase such property from such Person), (b) all obligations of such Person
evidenced by bonds, debentures, notes or similar instruments, (c) all
obligations of such Person under conditional sale or other title retention
agreements relating to property acquired by such Person, (d) all obligations of
such Person in respect of the deferred purchase price of property or services
(excluding current accounts payable incurred in the ordinary course of
business), (e) all Indebtedness of others secured by (or for which the holder
of such Indebtedness has an existing right, contingent or otherwise, to be
secured by) any Lien on property owned or acquired by such Person, whether or
not the Indebtedness secured thereby has been assumed, (f) all Guarantees by
such Person of Indebtedness of others, (g) all Capital Lease Obligations of
such Person, (h) all obligations, contingent or





                   Second Secured Vendor Financing Agreement
<PAGE>   14
                                     - 9 -



otherwise, of such Person as an account party in respect of letters of credit
and letters of guaranty and (i) all obligations, contingent or otherwise, of
such Person in respect of bankers' acceptances.  The Indebtedness of any Person
shall include the Indebtedness of any other entity (including any partnership
in which such Person is a general partner) to the extent such Person is liable
therefor as a result of such Person's ownership interest in or other
relationship with such entity, except to the extent the terms of such
Indebtedness provide that such Person is not liable therefor.

                 "Indemnified Taxes" means all Taxes other than (a) Excluded
Taxes and Other Taxes and (b) amounts constituting penalties or interest
imposed with respect to Excluded Taxes or Other Taxes.

                 "Intercreditor and Collateral Agency Agreement" means the
Intercreditor and Collateral Agency Agreement dated as of September 27, 1996
between the Restricted Companies, the Vendors, the Administrative Agent and the
Collateral Agent.

                 "Interest Coverage Ratio" means, as at any day, the ratio of
(a) Annualized Operating Cash Flow as at such day to (b) Interest Expense for
NCI and the Restricted Companies for the period of four fiscal quarters ending
on or most recently ended prior to such day.

                 "Interest Expense" means, for any period, the following:

                 (a)  in the case of the Restricted Companies, the sum of (i)
         all interest and fees in respect of Indebtedness accrued or
         capitalized during such period, including the interest component of
         any payments in respect of Capital Lease Obligations, but excluding
         any interest not required to be paid in cash during such period, plus
         (ii) all Restricted Payments made by any Restricted Company to NCI
         during such period to enable NCI to pay interest in respect of
         Indebtedness of NCI, as permitted by Section 7.05, plus (iii) the net
         amount payable (or minus the net amount receivable) under Hedging
         Agreements during such period (whether or not actually paid or
         received during such period); and

                 (b)  in the case of NCI and the Restricted Companies, the sum
         of (i) all interest and fees in respect of Indebtedness accrued or
         capitalized during such period, including the interest component of
         any payments in respect of Capital Lease Obligations, but excluding
         any interest not required to be paid in cash during such period, plus
         (ii) the net amount payable (or minus the net amount receivable) under
         Hedging Agreements during such period (whether or not actually paid or
         received during such period).





                   Second Secured Vendor Financing Agreement
<PAGE>   15
                                     - 10 -



"Interest Expense" for the Restricted Companies shall be determined on a
combined basis, and for NCI and the Restricted Companies shall be determined on
a consolidated basis (excluding the Unrestricted Companies), in each case
without duplication in accordance with GAAP.

                 "January 1994 Indenture" means the Indenture referred to in
clause (c) of the definition of the term "Public Note Indentures" in this
Section 1.01.

                 "Joinder Agreement" means a Joinder Agreement substantially in
the form of Exhibit E.

                 "Lenders" means the "Lenders" from time to time party to the
Credit Agreement.

                 "License Company" means any Restricted Company that holds any
FCC Licenses or PUC Authorizations.

                 "Lien" means, with respect to any asset, (a) any mortgage,
deed of trust, lien, pledge, hypothecation, encumbrance, charge or security
interest in, on or of such asset, (b) the interest of a vendor or a lessor
under any conditional sale agreement, capital lease or title retention
agreement (or any financing lease having substantially the same economic effect
as any of the foregoing) relating to such asset and (c) in the case of
securities, any purchase option, call or similar right of a third party (other
than a Restricted Company) with respect to such securities.

                 "Material Adverse Effect" means a material adverse effect on
(a) the business, assets, operations, prospects or condition, financial or
otherwise, of NCI and its subsidiaries, or of the Restricted Companies, in each
case taken as a whole, (b) the ability of any of NCI and the Restricted
Companies to perform any of their respective obligations under this Agreement
or the other Second Secured Loan Documents or (c) the rights of or benefits
available to the Vendor Lenders under this Agreement and the other Second
Secured Loan Documents.

                 "Material Indebtedness" means Indebtedness (other than the
Tranche D Loans), or obligations in respect of one or more Hedging Agreements,
of any one or more of the Credit Parties in an aggregate principal amount
exceeding $10,000,000.  For purposes of determining Material Indebtedness, the
"principal amount" of the obligations of any Credit Party in respect of any
Hedging Agreement at any time shall be the maximum aggregate amount (giving
effect to any netting agreements) that such Credit Party would be required to
pay if such Hedging Agreement were terminated at such time.





                   Second Secured Vendor Financing Agreement
<PAGE>   16
                                     - 11 -



                 "Maturity Date" means the last Business Day in June, 2003.

                 "Mobile Communications Business" means the business consisting
of (a) owning, operating or managing one or more SMR Systems and (b) to the
extent ancillary thereto and not constituting a material part of the operations
as a whole, other communications businesses related thereto which utilize the
training or resources appurtenant to the operation of an SMR System, including
radio paging services or sales or servicing of radio equipment or mechanical
parts and mobile telephone services, provided that such term shall not include
the ownership, operation or management of licenses for 1.8 GHz "personal
communications services" pursuant to Part 24.

                 "Mortgages" means, collectively, one or more assignments of
lease, mortgages, deeds of trust, deeds to secure debt and similar instruments
executed by a Restricted Company in favor of the Collateral Agent (or a trustee
for the benefit of the Collateral Agent), and covering interests in real
property held by such Restricted Company as collateral security for the
"Secured Obligation" under and as defined in the Intercreditor and Collateral
Agency Agreement and the Second Secured Intercreditor and Collateral Agency
Agreement, in each case in such form as shall be satisfactory to the Collateral
Agent.

                 "Motorola" means Motorola, Inc., a Delaware corporation.

                 "Multiemployer Plan" means a multiemployer plan as defined in
Section 4001(a)(3) of ERISA.

                 "NCI" means Nextel Communications, Inc., a Delaware
corporation.

                 "Net Cash Payments" means, with respect to any Disposition,
the aggregate amount of all cash payments received by the Restricted Companies
directly or indirectly in connection with such Disposition, whether at the time
of such Disposition or after such Disposition under deferred payment
arrangements or Investments entered into or received in connection with such
Disposition (including Disposition Investments); provided that

                 (a)  Net Cash Payments shall be net of (i) the amount of any
         legal, title and recording tax expenses, commissions and other fees
         and expenses payable by the Restricted Companies in connection with
         such Disposition and (ii) any Federal, state and local income or other
         taxes estimated to be payable by the Restricted Companies as a result
         of such Disposition, but only to the extent that on the date of such
         Disposition the Borrower delivers a certificate of a Financial Officer
         setting forth a calculation of the amount of such estimated taxes and
         delivers an amount of such Net Cash Payments equal to such estimated
         taxes to the Collateral Agent to be held in the





                   Second Secured Vendor Financing Agreement
<PAGE>   17
                                     - 12 -



         Tax Proceeds Account until such payment of taxes is in fact made, it
         being understood that to the extent the amount so deposited is not
         applied to such payment of taxes by the March 15 of the year
         immediately following the fiscal year in which such Disposition shall
         have occurred, the remaining balance shall be treated as "Net Cash
         Payments" for purposes of this Agreement and shall be applied in
         accordance with the provisions of Section 2.09(b)(ii) (and, in the
         event the Borrower shall elect, pursuant to Section 2.09(b)(ii)(y) to
         reinvest such remaining balance into replacement assets, the
         twelve-month period provided for in Section 2.09(b)(ii)(z) shall be
         measured from such March 15), and

                 (b)  Net Cash Payments shall be net of any repayments by the
         Restricted Companies of Indebtedness or other obligations to the
         extent that (i) such Indebtedness or other obligations is secured by a
         Lien on the property that is the subject of such Disposition and the
         transferee of (or holder of a Lien on) such property requires that
         such Indebtedness or other obligations be repaid as a condition to the
         purchase of such property or (ii) such Indebtedness or other
         obligations requires that it be repaid as a condition to such
         Disposition.

                 "Net Income" means, for any period, the net income of the
Restricted Companies (determined on a combined basis without duplication in
accordance with GAAP) and treating as operating expenses all amounts paid by
the Restricted Companies to NCI pursuant to the Overhead Services Agreement.

                 "Network Subscriber Units" means, as at any date, the number
of units (described as mobile stations within the meaning of Part 90),
employing analog or digital technology, subscribing to, and paying for,
communications services provided by the Restricted Companies for a period of
not less than 30 days as of such date, excluding any such unit to the extent
the accounts receivable generated by operation of such unit are more than 90
days past due as of such date.

                 "Operating Cash Flow" means, for any period, the sum, for the
Restricted Companies (determined on a combined basis without duplication in
accordance with GAAP), of the following (in each case adjusted to exclude all
extraordinary and unusual items, income or loss attributable to equity in
affiliates and non-cash minority interest payments and receipts):  (a) Net
Income for such period plus (b) income tax expense and Interest Expense (to the
extent deducted in determining Net Income) for such period plus (c)
depreciation, amortization and other non-cash charges (to the extent deducted
in determining Net Income) for such period.

                 "Other Taxes" means any and all present or future stamp or
documentary taxes or any other excise or property taxes, charges or similar
levies arising from any payment





                   Second Secured Vendor Financing Agreement
<PAGE>   18
                                     - 13 -



made hereunder or from the execution, delivery or enforcement of, or otherwise
with respect to, this Agreement and the other Second Secured Loan Documents,
provided that there shall be excluded from "Other Taxes" all Excluded Taxes.

                 "Overhead Services Agreement" means the Overhead Services
Agreement dated as of September 27, 1996, between the Restricted Companies and
NCI.

                 "Part 24" means 47 CFR Part 24 of the Rules and Regulations of
the FCC in effect from time to time or such other parts or subparts that may be
substituted for or combined with said Part 24.

                 "Part 90" means 47 CFR Part 90 of the Rules and Regulations of
the FCC in effect from time to time or such other parts or subparts that may be
substituted for or combined with said Part 90.

                 "PBGC" means the Pension Benefit Guaranty Corporation referred
to and defined in ERISA and any successor entity performing similar functions.

                 "Permitted Debt Limitation" means, at any date, the amount of
Indebtedness permitted to be incurred on such date pursuant to clause (iii) of
the definition of "Permitted Debt" under each of the Public Note Indentures.

                 "Permitted Encumbrances" means:

                 (a)  Liens imposed by law for taxes that are not yet due or
         are being contested in compliance with Section 6.04;

                 (b)  carriers', warehousemen's, mechanics', landlord's,
         lessor's, materialmen's, repairmen's and other like Liens imposed by
         law, arising in the ordinary course of business and securing
         obligations that are not overdue by more than 30 days or are being
         contested in compliance with Section 6.04;

                 (c)  pledges and deposits made in the ordinary course of
         business in compliance with workers compensation, unemployment
         insurance and other social security laws or regulations;

                 (d)  deposits to secure the performance of bids, trade
         contracts, leases, statutory obligations, surety and appeal bonds,
         performance bonds and other obligations of a like nature, in each case
         in the ordinary course of business;





                   Second Secured Vendor Financing Agreement
<PAGE>   19
                                     - 14 -



                 (e)  easements, zoning restrictions, rights-of-way and similar
         encumbrances on real property imposed by law or arising in the
         ordinary course of business that do not secure any monetary
         obligations and do not materially detract from the value of the
         affected property or interfere with the ordinary conduct of business
         of any Restricted Company;

                 (f)  subleases of property with respect to which a Restricted
         Company is the primary lessee, to the extent such subleases arise in
         the ordinary course of business and do not interfere in any material
         respect with the business of any Restricted Company; and

                 (g)  precautionary Uniform Commercial Code filings made with
         respect to office and similar equipment (but excluding equipment used
         in the operation of the Mobile Communications Business of the
         Restricted Companies), or vehicles, leased to the Restricted Companies
         in the ordinary course of business under operating leases (i.e. leases
         not giving rise to Capital Lease Obligations);

provided that the term "Permitted Encumbrances" shall not include any Lien
securing Indebtedness.

                 "Permitted Investments" means:

                 (a)  direct obligations of, or obligations the principal of
         and interest on which are unconditionally guaranteed by, the United
         States of America (or by any agency thereof to the extent such
         obligations are backed by the full faith and credit of the United
         States of America), in each case maturing within one year from the
         date of acquisition thereof;

                 (b)  investments in commercial paper maturing within 270 days
         from the date of acquisition thereof and having, at such date of
         acquisition, the highest credit rating obtainable from Standard and
         Poor's Ratings Service or from Moody's Investors Service, Inc.;

                 (c)  investments in certificates of deposit, banker's
         acceptances and time deposits maturing within 180 days from the date
         of acquisition thereof issued or guaranteed by or placed with, and
         money market deposit accounts issued or offered by, (i) any domestic
         office of any commercial bank organized under the laws of the United
         States of America or any State thereof which has a combined capital
         and surplus and undivided profits of not less than $250,000,000 or
         (ii) any office of any of The Chase Manhattan Bank, Morgan Guaranty
         Trust Company of New York or The Toronto-Dominion Bank located in the
         United Kingdom or the Bahamas; and





                   Second Secured Vendor Financing Agreement
<PAGE>   20
                                     - 15 -




                 (d)  fully collateralized repurchase agreements with a term of
         not more than 30 days for securities described in clause (a) above and
         entered into with a financial institution satisfying the criteria
         described in clause (c) above.

                 "Person" means any natural person, corporation, limited
liability company, trust, joint venture, association, company, partnership,
Governmental Authority or other entity.

                 "Plan" means any employee pension benefit plan (other than a
Multiemployer Plan) subject to the provisions of Title IV of ERISA or Section
412 of the Code or Section 302 of ERISA, and in respect of which the Borrower
or any ERISA Affiliate is (or, if such plan were terminated, would under
Section 4069 of ERISA be deemed to be) an "employer" as defined in Section 3(5)
of ERISA.

                 "Planned Option Issuances" means the warrants, options and
other rights to acquire shares of stock of NCI set forth in Part A of Schedule
4.15 to the Vendor Financing Agreement.

                 "Prime Rate" means the rate of interest per annum publicly
announced from time to time by The Chase Manhattan Bank as its prime rate in
effect at its principal office in New York City; each change in the Prime Rate
shall be effective from and including the date such change is publicly
announced as being effective.

                 "Pro-Forma Debt Service" means, as at the last day of any
fiscal quarter, the sum, for NCI and the Restricted Companies (determined on a
consolidated basis without duplication in accordance with GAAP), of the
following:  (a) the amount, if any, by which the aggregate principal amount of
"Revolving Credit Loans" outstanding under the Credit Agreement on such day
exceeds the aggregate amount of the "Revolving Credit Commitments" thereunder
scheduled pursuant to Section 2.07 of the Credit Agreement to be in effect at
the last day of the immediately succeeding four fiscal quarters plus (b) the
amount, if any, by which the aggregate principal amount of Tranche B Loans
outstanding under the Vendor Financing Agreement on such day exceeds the
aggregate amount of the Tranche B Commitment scheduled pursuant to Section 2.07
of the Vendor Financing Agreement to be in effect at the last day of the
immediately succeeding four fiscal quarters plus (c) all regularly scheduled
payments or regularly scheduled mandatory prepayments of principal of any other
Indebtedness (including the "Tranche A Loans" and "Tranche C Loans" under the
Vendor Financing Agreement, the "Tranche C Term Loans", the "Tranche D Term
Loans" and the "Tranche E Loans" under the Credit Agreement and the principal
component of any payments in respect of Capital Lease Obligations, but
excluding any prepayments made pursuant to Section 2.09) required to be made
during the immediately succeeding four fiscal quarters plus (d) all Interest
Expense for NCI and the Restricted





                   Second Secured Vendor Financing Agreement
<PAGE>   21
                                     - 16 -



Companies projected to be incurred during the immediately succeeding four
fiscal quarters.  In determining Interest Expense for purposes of this
definition, interest on a floating rate basis for any current or future period
shall be deemed to accrue at a rate per annum equal to the higher of (i) the
weighted average rate of interest with respect to all Indebtedness of NCI and
the Restricted Companies in effect on the last day of the fiscal quarter as of
which "Pro-Forma Debt Service" is being determined and (ii) the weighted
average rate of interest with respect to such Indebtedness in effect during
such fiscal quarter.

                 "Pro-Forma Debt Service Ratio" means, as at the last day of
any fiscal quarter, the ratio of (a) Annualized Operating Cash Flow as at such
day to (b) Pro-Forma Debt Service as at such day.

                 "Public Note Indentures" means (a) the Indenture dated as of
August 15, 1993 between NCI and The Bank of New York, as Trustee, (b) the
Indenture dated as of December 22, 1993 between NCI (as successor to Dial Call
Communications, Inc.) and The Bank of New York, as Trustee, (c) the Indenture
dated as of January 13, 1994 between NCI (as successor to CenCall
Communications Corp.) and The Bank of New York, as Trustee, (d) the Indenture
dated as of February 15, 1994 between NCI and The Bank of New York, as Trustee
and (e) the Indenture dated as of April 24, 1994 between NCI (as successor to
Dial Call Communications, Inc.) and The Bank of New York, as Trustee.

                 "Public Notes" means, collectively, the respective Notes
issued pursuant to the Public Note Indentures.

                 "PUC" means any state regulatory agency or body that exercises
jurisdiction over the rates or services or the ownership, construction or
operation of any SMR System, cellular radio telecommunications system or
conventional mobile telephone system or over Persons who own, construct or
operate SMR Systems, cellular radio telecommunications systems or conventional
mobile telephone systems, in each case by reason of the nature or type of the
business subject to regulation and not pursuant to laws and regulations of
general applicability to Persons conducting business in said state.

                 "PUC Authorization" means any Authorization issued by a PUC.

                 "Purchase Price" means with respect to any acquisition under
Section 7.04(a)(viii), an amount equal to the sum of (i) the aggregate
consideration, whether cash, property or securities (including any Indebtedness
incurred pursuant to Section 7.01(g) hereof), paid or delivered by the
Restricted Companies in connection with such acquisition plus (ii) the
aggregate amount of liabilities of the acquired business (net of current assets
of the acquired business) that would be reflected on a balance sheet (if such
were to be prepared) of the Restricted Companies after giving effect to such
acquisition.





                   Second Secured Vendor Financing Agreement
<PAGE>   22
                                     - 17 -




                 "Qualifying Debt or Equity Issuance" means (a) the issuance or
incurrence by NCI after September 27, 1996, of Indebtedness permitted under
Section 7.01 and (b) the issuance or sale by NCI after September 27, 1996 of
(i) any shares of capital stock (including any such shares issued upon the
exercise or conversion of any existing warrants, options or other rights to
acquire shares of capital stock), (ii) any warrants or options exercisable in
respect of capital stock or (iii) any other security or instrument representing
an equity interest (or the right to obtain any equity interest) in NCI.

                 "Quarterly Dates" means the last Business Day of March, June,
September and December in each year, the first of which shall be the first such
day after the date of this Agreement.

                 "Related Parties" means, with respect to any specified Person,
such Person's Affiliates and the respective directors, officers, employees,
agents and advisors of such Person and such Person's Affiliates.

                 "Required Vendor Lenders" means, at any time, Vendor Lenders
having Tranche D Loans and unused Tranche D Commitments representing at least
51% of the sum of the total Tranche D Loans and unused Tranche D Commitments at
such time.

                 "Required Parties" means, at any time, Vendor Lenders and
Vendors having Tranche D Loans hereunder and "Loans" under the Vendor Financing
Agreement, and unused Tranche D Commitments hereunder and "Commitments" under
the Vendor Financing Agreement, representing at least 51% of the sum of the
total Tranche D Loans and such "Loans" and unused Tranche D Commitments and
such "Commitments" at such time.

                 "Restricted Company" means the Borrower, the other Persons
listed on the signature pages hereto under the caption "RESTRICTED COMPANIES"
and each Person that becomes a Restricted Company after the date hereof
pursuant to Section 6.11.

                 "Restricted Company Guarantee and Security Agreement" means
the  Guarantee and Security Agreement dated as of September 27, 1996 between
the Restricted Companies and the Collateral Agent (a copy of which is attached
a Exhibit C-1), as heretofore amended by Amendment No. 1 (a copy of which is
attached as Exhibit C-2) and as further amended by an Amendment No. 2
substantially in the form of Exhibit C-3.

                 "Restricted Payment" means any dividend or other distribution
(whether in cash, securities or other property) with respect to any shares of
any class of capital stock of any Restricted Company, or any payment (whether
in cash, securities or other property), including any sinking fund or similar
deposit, on account of the purchase, redemption, retirement, acquisition,
cancellation or termination of any such shares of capital stock of any





                   Second Secured Vendor Financing Agreement
<PAGE>   23
                                     - 18 -



Restricted Company or any option, warrant or other right to acquire any such
shares of capital stock of any Restricted Company, but excluding any such
dividend, distribution or payment either (i) made solely in shares of its
common stock or (ii) made to any other Restricted Company.

                 "RF Emissions" means radio frequency emissions governed by FCC
rules and policies.

                 "Sale Proceeds Reinvestment Account" has the meaning assigned
to such term in the Restricted Company Guarantee and Security Agreement.

                 "Second Secured Intercreditor and Collateral Agency Agreement"
means a Second Secured Intercreditor and Collateral Agency Agreement
substantially in the form of Exhibit D between the Restricted Companies, the
Vendor Lenders and the Collateral Agent.

                 "Second Secured Loan Documents" means this Agreement, any
promissory notes evidencing Tranche D Loans hereunder and the Security
Documents.

                 "Secured Indebtedness" means, as at any day, all Indebtedness
of the Restricted Companies hereunder and under the Credit Agreement and the
Vendor Financing Agreement, and all other Indebtedness that is secured by any
Lien upon property of any of the Restricted Companies, including all Capital
Lease Obligations.

                 "Secured Indebtedness to Cash Flow Ratio" means, as at the
last day of any fiscal quarter, the ratio of (a) Secured Indebtedness as at
such day to (b) Annualized Operating Cash Flow as at such day.

                 "Secured Indebtedness to Revenue Ratio" means, as at any day,
the ratio of (a) Secured Indebtedness as at such day to (b) Annualized Revenue
as at such day.

                 "Security Documents" means the Restricted Company Guarantee
and Security Agreement, the Second Secured Intercreditor and Collateral Agency
Agreement, the Mortgages and all Uniform Commercial Code financing statements
required by any of such instruments to be filed with respect to the security
interests in personal property and fixtures created pursuant thereto.

                 "Senior Termination Date" shall have the meaning assigned to
such term in the Second Secured Intercreditor and Collateral Agency Agreement.

                 "SMR License" means an FCC License authorizing the
construction, ownership and operation of an SMR System in the 800 or 900 MHz
band.





                   Second Secured Vendor Financing Agreement
<PAGE>   24
                                     - 19 -




                 "SMR System" means a specialized mobile radio system licensed
under Part 90, together with such other facilities from time to time licensed
or otherwise authorized by the FCC as shall be necessary to provide the
communications services to be offered by the Restricted Companies.  The term
"SMR System" shall include an Enhanced SMR System using FCC Licenses in the 800
MHz or 900 MHz band.

                 "Specified Default" means any Event of Default under paragraph
(a), (b), (d), (f), (g), (h) or (i) of Article VIII.

                 "subsidiary" means, with respect to any Person (the "parent")
at any date, any corporation, limited liability company, partnership,
association or other entity the accounts of which would be consolidated with
those of the parent in the parent's consolidated financial statements if such
financial statements were prepared in accordance with GAAP as of such date, as
well as any other corporation, limited liability company, partnership,
association or other entity (a) of which securities or other ownership
interests representing more than 50% of the ordinary voting power or, in the
case of a partnership, more than 50% of the general partnership interests are,
as of such date, owned, controlled or held, or (b) that is, as of such date,
otherwise Controlled, by the parent or one or more subsidiaries of the parent
or by the parent and one or more subsidiaries of the parent.

                 "Subsidiary" means any subsidiary of the Borrower.

                 "Tax Proceeds Account" has the meaning assigned to such term
in the Restricted Company Guarantee and Security Agreement.

                 "Tax Sharing Agreement" means the Tax Sharing Agreement dated
as of September 27, 1996 by and among NCI and the "Affiliated Corporations"
(including the Restricted Companies) therein referred to.

                 "Taxes" means any and all present or future taxes, levies,
imposts, duties, deductions, charges or withholdings imposed by any
Governmental Authority.

                 "Total Indebtedness" means, as at any day, all Indebtedness of
NCI and the Restricted Companies, determined on a consolidated basis (excluding
the Unrestricted Companies) without duplication in accordance with GAAP.

                 "Total Indebtedness to Cash Flow Ratio" means, as at the last
day of any fiscal quarter, the ratio of (a) Total Indebtedness as at such day
to (b) Annualized Operating Cash Flow as at such day.





                   Second Secured Vendor Financing Agreement
<PAGE>   25
                                     - 20 -



                 "Tranche D Commitment" means, with respect to any Vendor
Lender, the commitment of such Vendor Lender to make Tranche D Loans hereunder,
as such commitment may be (a) reduced from time to time pursuant to Sections
2.07 and 2.09 or (b) reduced or increased from time to time pursuant to
assignments by or to such Vendor Lender pursuant to Section 10.04.  The initial
aggregate amount of the Tranche D Commitments is $200,000,000.

                 "Tranche D Commitment Termination Date" means the Quarterly
Date falling on or nearest to March 31, 1999.

                 "Tranche D Loan" means a loan made pursuant to Section 2.01.

                 "Transactions" means (a) with respect to the Borrower, the
execution, delivery and performance by the Borrower of the Second Secured Loan
Documents to which it is a party and the borrowing of Tranche D Loans and the
use of the proceeds thereof and (b) with respect to any Credit Party (other
than the Borrower), the execution, delivery and performance by such Credit
Party of the Second Secured Loan Documents to which it is a party.

                 "Unrestricted Companies" means each subsidiary of NCI other
than the Restricted Companies.

                 "U.S. dollars" or "$" refers to lawful money of the United
States of America.

                 "Vendor Equipment Agreements" means the following agreements
(i) the Enhanced Specialized Mobile Radio System Equipment Purchase Agreement
dated as of November 1, 1991 between Motorola and NCI; (ii) the letter
agreement dated as of November 4, 1991 between Motorola and NCI; (iii)
Amendment to Purchase Agreements dated as of August 4, 1994 between Motorola
and NCI; (iv) Second Amendment to Purchase Agreements dated as of April 5, 1995
between Motorola and NCI; (v) Amendment 003 to Enhanced Specialized Mobile
Radio System Purchase Agreement dated as of March 25, 1995 between Motorola and
NCI; and (vi) Amendment 004 to Enhanced Specialized Mobile Radio System
Purchase Agreement dated as of April 28, 1996 between Motorola and NCI; each of
which agreements and Amendments is, pursuant to the assignment referred to in
Section 5.01(m), being assigned to the Borrower on the Effective Date.

                 "Vendor Financing Agreement" means the Amended, Restated and
Consolidated Credit Agreement dated as of September 27, 1996 among NCI, the
Restricted Companies, NTFC Capital Corporation and Motorola.





                   Second Secured Vendor Financing Agreement
<PAGE>   26
                                     - 21 -



                 "Vendor Lenders" means Motorola (which on the date hereof is
the only Vendor Lender) and any other Person that shall become a party hereto
as a "Vendor Lender" pursuant to Section 10.04.

                 "Vendors" means the "Vendors" from time to time party to the
Vendor Financing Agreement.

                 "Wholly Owned Subsidiary" means, with respect to any Person at
any date, any corporation, limited liability company, partnership, association
or other entity of which securities or other ownership interests representing
100% of the equity or ordinary voting power (other than directors' qualifying
shares) or, in the case of a partnership, 100% of the general partnership
interests are, as of such date, directly or indirectly owned, controlled or
held by such Person or one or more Wholly Owned Subsidiaries of such Person or
by such Person and one or more Wholly Owned Subsidiaries of such Person.

                 "Withdrawal Liability" means liability to a Multiemployer Plan
as a result of a complete or partial withdrawal from such Multiemployer Plan,
as such terms are defined in Part I of Subtitle E of Title IV of ERISA.

                 SECTION 1.02.  Intentionally Left Blank.  This Section 1.02
has been intentionally left blank.

                 SECTION 1.03.  Terms Generally.  The definitions of terms
herein shall apply equally to the singular and plural forms of the terms
defined.  Whenever the context may require, any pronoun shall include the
corresponding masculine, feminine and neuter forms.  The words "include",
"includes" and "including" shall be deemed to be followed by the phrase
"without limitation".  The word "will" shall be construed to have the same
meaning and effect as the word "shall".  Unless the context requires otherwise
(a) any definition of or reference to any agreement, instrument or other
document herein shall be construed as referring to such agreement, instrument
or other document as from time to time amended, supplemented or otherwise
modified (subject to any restrictions on such amendments, supplements or
modifications set forth herein), (b) any reference herein to any Person shall
be construed to include such Person's successors and assigns, (c) the words
"herein", "hereof" and "hereunder", and words of similar import, shall be
construed to refer to this Agreement in its entirety and not to any particular
provision hereof, (d) all references herein to Articles, Sections and Exhibits
shall be construed to refer to Articles and Sections of, and Exhibits to, this
Agreement and (e) the words "asset" and "property" shall be construed to have
the same meaning and effect and to refer to any and all tangible and intangible
assets and properties, including cash, securities, accounts and contract
rights.





                   Second Secured Vendor Financing Agreement
<PAGE>   27
                                     - 22 -



                 SECTION 1.04.  Accounting Terms; GAAP.  Except as otherwise
expressly provided herein, all terms of an accounting or financial nature shall
be construed in accordance with GAAP, as in effect from time to time; provided
that, if the Borrower and NCI notify the Vendor Lenders that the Borrower and
NCI request an amendment to any provision hereof to eliminate the effect of any
change occurring after the date hereof in GAAP or in the application thereof on
the operation of such provision (or if the Required Vendors notify the Borrower
and NCI that they request an amendment to any provision hereof for such
purpose), regardless of whether any such notice is given before or after such
change in GAAP or in the application thereof, then such provision shall be
interpreted on the basis of GAAP as in effect and applied immediately before
such change shall have become effective until such notice shall have been
withdrawn or such provision amended in accordance herewith.

                 SECTION 1.05.  Tax Sharing Agreement.  Pursuant to the Tax
Sharing Agreement, the Restricted Companies have agreed to join the affiliated
group headed by NCI as "common parent" (within the meaning of Section 1504 of
the Code) in filing consolidated Federal, and (in certain circumstances) state
and local, income tax returns and have also agreed as to the amounts, if any,
that the Restricted Companies shall be obligated to pay to NCI in respect of
Federal, state and local income taxes (or the amounts that the Restricted
Companies shall be entitled to receive as refunds in respect of such taxes).
So long as the Restricted Companies shall be included in consolidated Federal,
state and local income tax returns filed by NCI pursuant to the Tax Sharing
Agreement, whenever making determinations under this Agreement of the amount of
such taxes payable during any period (or the amount of refunds in respect of
such taxes receivable during any period) by the Restricted Companies, the
amount of such taxes payable or receivable shall be deemed to be equal to the
amounts payable or receivable, as the case may be, in respect of such taxes
under the Tax Sharing Agreement without reference to whether NCI and its
subsidiaries as an affiliated group shall in fact pay any amounts in respect of
Federal, state and local income taxes (or receive any amounts in respect of
refunds of such taxes) during the relevant period.


                                   ARTICLE II

                                  The Credits

                 SECTION 2.01.  The Tranche D Commitments.  Subject to the
terms and conditions set forth herein, each Vendor Lender agrees to make
Tranche D Loans to the Borrower from time to time during the Availability
Period in an aggregate principal amount that will not result in such Vendor
Lender's Tranche D Loans exceeding such Vendor Lender's Tranche D Commitment.
Once borrowed and repaid, Tranche D Loans may not be reborrowed.





                   Second Secured Vendor Financing Agreement
<PAGE>   28
                                     - 23 -




                 SECTION 2.02.  Tranche D Loans and Borrowings.  At the time
that each Borrowing is made, such Borrowing shall be in an aggregate amount
that is an integral multiple of $500,000 and not less than $1,000,000; provided
that a Borrowing of Tranche D Loans may be in an aggregate amount that is equal
to the entire unused balance of the Tranche D Commitments.

                 SECTION 2.03.  Requests for Borrowings.  To request a
Borrowing, the Borrower shall notify the respective Vendor Lender of such
request by telephone not later than 11:00 a.m., New York City time, one
Business Day before the date of the proposed Borrowing.  Each such telephonic
Borrowing Request shall be irrevocable and shall be confirmed promptly by hand
delivery or telecopy to such Vendor Lender of a written Borrowing Request in a
form approved by such Vendor Lender and signed by the Borrower.  Each such
telephonic and written Borrowing Request shall specify the following
information in compliance with Section 2.02:

                            (i)  the aggregate amount of such Borrowing;

                           (ii)  the date of such Borrowing, which shall be a
         Business Day; and

                          (iii)  the location and number of the Borrower's
         account to which funds are to be disbursed, which shall comply with
         the requirements of Section 2.05.

                 SECTION 2.04.  Intentionally Left Blank.  This Section 2.04
has been intentionally left blank.

                 SECTION 2.05.  Funding of Borrowings.  Each Vendor Lender
shall make each Tranche D Loan to be made by it hereunder on the proposed date
thereof by wire transfer of immediately available funds by 12:00 noon, New York
City time, to an account of the Borrower at a bank designated by the Borrower
in the applicable Borrowing Request.

                 SECTION 2.06.  Intentionally Left Blank.  This Section 2.06
has been intentionally left blank.

                 SECTION 2.07.  Termination and Reduction of Tranche D
Commitments.

                 (a)  The aggregate amount of the Tranche D Commitments shall
automatically terminate at the close of business on the Tranche D Commitment
Termination Date.

                 (b)  The Borrower may at any time terminate, or from time to
time reduce, the Tranche D Commitments; provided that (i) each reduction of the
Tranche D Commitments shall be in an amount that is an integral multiple of
$1,000,000 and not less than $5,000,000





                   Second Secured Vendor Financing Agreement
<PAGE>   29
                                     - 24 -



and (ii) the Borrower shall not terminate or reduce the Tranche D Commitments
if, after giving effect to any concurrent prepayment of Tranche D Loans in
accordance with Section 2.09, the outstanding Tranche D Loans would exceed the
Tranche D Commitments.

                 (c)  The Borrower shall notify each Vendor Lender of any
election to terminate or reduce the Tranche D Commitments under paragraph (b)
of this Section 2.07 at least three Business Days prior to the effective date
of such termination or reduction, specifying such election and the effective
date thereof.  Each notice delivered by the Borrower pursuant to this Section
2.07 shall be irrevocable; provided that a notice of termination of the Tranche
D Commitments delivered by the Borrower may state that such notice is
conditioned upon the effectiveness of other credit facilities, in which case
such notice may be revoked by the Borrower (by notice to the Vendor Lenders on
or prior to the specified effective date) if such condition is not satisfied.
Any termination or reduction of Tranche D Commitments shall be permanent.

                 SECTION 2.08.  Repayment of Tranche D Loans; Evidence of Debt.

                 (a)  The Borrower hereby unconditionally promises to pay to
each Vendor Lender the then unpaid principal amount of such Vendor Lender's
Tranche D Loans on the Maturity Date.

                 (b)  Each Vendor Lender shall maintain in accordance with its
usual practice an account or accounts evidencing the indebtedness of the
Borrower to such Vendor Lender resulting from each Tranche D Loan made by such
Vendor Lender, including the amounts of principal and interest payable and paid
to such Vendor Lender from time to time hereunder and shall make such account
or accounts available to the Borrower or an authorized representative of the
Borrower upon the Borrower's request.

                 (c)  The entries made in the accounts maintained pursuant to
paragraph (b) of this Section 2.08 shall be prima facie evidence of the
existence and amounts of the obligations recorded therein; provided that the
failure of any Vendor Lender to maintain such accounts or any error therein
shall not in any manner affect the obligation of the Borrower to repay the
Tranche D Loans in accordance with the terms of this Agreement.

                 (d)  Each Tranche D Loan made by a Vendor Lender hereunder
shall be evidenced by a promissory note in a form (that shall be prepared by
the Borrower, and executed and delivered to such Vendor Lender) satisfactory to
such Vendor Lender.





                   Second Secured Vendor Financing Agreement
<PAGE>   30
                                     - 25 -



                 SECTION 2.09.  Prepayment of Tranche D Loans.

                 (a)  Optional Prepayments.  The Borrower shall have the right
at any time and from time to time to prepay any Borrowing in whole or in part,
subject to prior notice in accordance with paragraph (d) of this Section 2.09.

                 (b)  Mandatory Prepayments -- After Senior Termination Date.
The Borrower shall make prepayments of the Tranche D Loans hereunder (or, if no
Tranche D Loans are outstanding hereunder, reduce the Tranche D Commitments) as
follows, provided that anything herein to the contrary notwithstanding, the
provisions of this paragraph (b) shall not be applicable, and the Borrower
shall not be required to make any prepayments under this paragraph (b) (and the
Tranche D Commitments shall not be subject to reduction), until after the
Senior Termination Date:

                          (i)  Excess Cash Flow.  Not later than the date 135
         days after the end of each fiscal year of the Borrower (commencing
         with Excess Cash Flow for the fiscal year ending on December 31,
         1999), the Borrower shall prepay the Tranche D Loans hereunder, in an
         aggregate amount equal to 50% of Excess Cash Flow for such fiscal
         year.

                          (ii)  Sale of Assets.  Without limiting the
         obligation of the Restricted Companies to obtain the consent of the
         Required Vendor Lenders to any Disposition not otherwise permitted
         hereunder, the Borrower agrees, on or prior to the occurrence of any
         Disposition (herein, the "Current Disposition") as to which the
         estimated amount of the Net Cash Payments, together with all prior
         Dispositions as to which a prepayment has not yet been made under this
         Section 2.09(b)(ii) and as to which a report contemplated by this
         Section 2.09(b)(ii) has not been delivered, shall exceed $5,000,000,
         to deliver to the Vendor Lenders a report certified by a Financial
         Officer, in form and detail reasonably satisfactory to the Required
         Vendor Lenders, with respect to such Current Disposition and all such
         prior Dispositions setting out the estimated amount of the Net Cash
         Payments of all such Dispositions that will (on the date of the
         Current Disposition) have been received in cash whereupon the Borrower
         will prepay the Tranche D Loans hereunder, and the Tranche D
         Commitments hereunder shall be subject to automatic reduction, as
         follows:

                          (w)  upon the date of the Current Disposition, in an
                 aggregate amount equal to 100% of such estimated amount of the
                 Net Cash Payments of the Current Disposition, to the extent
                 received in cash on the date of the Current Disposition,
                 together with 100% of the Net Cash Payments of all such prior
                 Dispositions; and





                   Second Secured Vendor Financing Agreement
<PAGE>   31
                                     - 26 -



                          (x)  thereafter, quarterly, on the date of the
                 delivery by the Borrower to the Vendor Lenders pursuant to
                 Section 6.01(c) of the financial statements for each quarterly
                 fiscal period or (if earlier) the date 60 days after the end
                 of such quarterly fiscal period, to the extent the Restricted
                 Companies shall receive Net Cash Payments during such
                 quarterly fiscal period in cash under deferred payment
                 arrangements or Disposition Investments entered into or
                 received in connection with any Disposition, an amount equal
                 to (A) 100% of the aggregate amount of such Net Cash Payments
                 minus (B) any transaction expenses associated with
                 Dispositions and not previously deducted in the determination
                 of Net Cash Payments plus (or minus, as the case may be) (C)
                 any other adjustment received or paid by the Restricted
                 Companies pursuant to the respective agreements giving rise to
                 Dispositions and not previously taken into account in the
                 determination of the Net Cash Payments of Dispositions,
                 provided that if prior to the date upon which the Borrower
                 would otherwise be required to make a prepayment under this
                 clause (x) with respect to any quarterly fiscal period the
                 aggregate amount of such Net Cash Payments (after giving
                 effect to the adjustments provided for in this clause (x))
                 shall exceed $5,000,000, then the Borrower shall within three
                 Business Days make a prepayment under this clause (x) in an
                 amount equal to such required prepayment.

                 Notwithstanding the foregoing, the Borrower shall not be
         required to make a prepayment pursuant to this Section 2.09(b)(ii)
         with respect to the Net Cash Payments from any Disposition in the
         event that the Borrower advises the Vendor Lenders at the time a
         prepayment is required to be made under the foregoing clauses (w) or
         (x) that it intends to reinvest such Net Cash Payments into
         replacement assets pursuant to an acquisition permitted under Section
         7.04(a)(vii) or 7.04(a)(viii), so long as:

                          (y)  such Net Cash Payments are delivered to the
                 Collateral Agent to be held in the Sale Proceeds Reinvestment
                 Account pending such reinvestment, in which event the
                 Collateral Agent need not release such Net Cash Payments
                 except upon presentation of evidence reasonably satisfactory
                 to it that such Net Cash Payments are to be so reinvested in
                 compliance with the provisions of this Agreement, and

                          (z)  the Net Cash Payments from any Disposition are
                 in fact so reinvested within twelve months of such Disposition
                 (it being understood that, in the event Net Cash Payments from
                 more than one Disposition are delivered to the Collateral
                 Agent, such Net Cash Payments shall be deemed to be released
                 in the same order in which such Dispositions occurred and,
                 accordingly, any such Net Cash Payments so held for more than
                 twelve





                   Second Secured Vendor Financing Agreement
<PAGE>   32
                                     - 27 -



                  months shall be forthwith applied to the prepayment of
                  Tranche D Loans and reductions of the Tranche D Commitments
                  as provided above).

         As contemplated by Article V of the Restricted Company Guarantee and
         Security Agreement, nothing in this Section 2.09(b)(ii) shall be
         deemed to obligate the Collateral Agent to release any of such
         proceeds from the Sale Proceeds Reinvestment Account to the Restricted
         Companies for purposes of reinvestment as aforesaid upon the
         occurrence and during the continuance of any Event of Default.

                      (iii)  Change in Control.  Upon the occurrence of any
         Change in Control, the Borrower shall prepay the Tranche D Loans
         hereunder in full, and the Tranche D Commitments hereunder shall be
         automatically terminated.

                 (c)  Mandatory Prepayments -- All Times.  In the event that,
after obtaining any necessary consent of the Lenders under the Credit Agreement
and of the Required Vendor Lenders, the aggregate principal amount of
Indebtedness under the Credit Agreement and the Vendor Financing Agreement
shall be increased to an amount greater than $2,300,000,000 then to the extent
required under Section 7.01(b), the Borrower shall prepay Tranche D Loans (or,
if no Tranche D Loans are outstanding hereunder, the Tranche D Commitments
hereunder shall be subject to automatic reduction), in an amount equal to such
excess over $2,300,000,000.

                 (d)  Notification of Prepayments.  The Borrower shall notify
the Vendor Lenders by telephone (confirmed by telecopy) of any prepayment
hereunder not later than 11:00 a.m., New York City time, one Business Day
before the date of prepayment.  Each such notice shall be irrevocable and shall
specify the prepayment date and the principal amount of each Borrowing or
portion thereof to be prepaid; provided that, if a notice of prepayment is
given in connection with a conditional notice of termination of the Tranche D
Commitments as contemplated by Section 2.07, then such notice of prepayment may
be revoked if such notice of termination is revoked in accordance with Section
2.07.  Each partial prepayment of any Borrowing under paragraph (a) of this
Section 2.09 shall be in an amount that would be permitted in the case of an
advance of a Borrowing as provided in Section 2.02.

                 (e)  Prepayments Accompanied by Interest.  Prepayments shall
be accompanied by accrued interest to the extent required by Section 2.11.





                   Second Secured Vendor Financing Agreement
<PAGE>   33
                                     - 28 -



                 SECTION 2.10.  Intentionally Left Blank.  This Section 2.10
has been intentionally left blank.

                 SECTION 2.11.  Interest.

                 (a)  The Tranche D Loans shall bear interest during any
calendar month at a rate per annum equal to the Prime Rate plus 2 and 3/8 of
1%. Notwithstanding the foregoing, commencing on the Senior Termination Date
and at all times thereafter, the Tranche D Loans shall bear interest at a rate
per annum equal to the Prime Rate plus 2%.

                 (b)  Notwithstanding the foregoing, (i) during the period when
any Specified Default shall have occurred and be continuing, the principal of
each Tranche D Loan hereunder shall bear interest, after as well as before
judgment, at a rate per annum equal to 2% plus the rate otherwise applicable to
such Tranche D Loan as provided above (the "Post-Default Rate") and (ii) if any
interest on any Tranche D Loan or any other amount payable by the Borrower
hereunder is not paid when due, whether at stated maturity, upon acceleration
or otherwise, such overdue amount shall bear interest, after as well as before
judgment, at a rate per annum equal to the Post-Default Rate.

                 (c)  Accrued interest on each Tranche D Loan shall be payable
in arrears on each Quarterly Date; provided that

                          (i)  interest accrued pursuant to paragraph (b) of
         this Section 2.11 shall be payable on demand, and

                          (ii)  interest accrued with respect to the Tranche D
         Loans during the period commencing on the Effective Date to and
         including the Quarterly Date falling on or nearest to March 31, 2001
         shall, at the Borrower's option, be paid by adding the amount of such
         interest to the principal of the Tranche D Loans on each Quarterly
         Date (but such amount shall not be treated as a Borrowing and shall
         not be applied to reduce the Tranche D Commitment of any Vendor
         Lender), and any interest so added to the principal of the Tranche D
         Loans shall bear interest as provided in this Section 2.11.

                 (d)  All interest hereunder shall be computed on the basis of
a year of 365 days (or 366 days in a leap year), and in each case shall be
payable for the actual number of days elapsed (including the first day but
excluding the last day).

                 SECTION 2.12.  Intentionally Left Blank.  This Section 2.12
has been intentionally left blank.





                   Second Secured Vendor Financing Agreement
<PAGE>   34
                                     - 29 -



                 SECTION 2.13.  Intentionally Left Blank.  This Section 2.13
has been intentionally left blank.

                 SECTION 2.14.  Intentionally Left Blank.  This Section 2.14
has been intentionally left blank.

                 SECTION 2.15.  Taxes.

                 (a)  Any and all payments by or on account of any obligation
of the Borrower hereunder shall be made free and clear of and without deduction
for any Indemnified Taxes or Other Taxes; provided that if the Borrower shall
be required to deduct any Indemnified Taxes or Other Taxes from such payments,
then (i) the sum payable shall be increased as necessary so that after making
all required deductions (including deductions applicable to additional sums
payable under this Section 2.15) the respective Vendor Lender receives an
amount equal to the sum it would have received had no such deductions been
made, (ii) the Borrower shall make such deductions and (iii) the Borrower shall
pay the full amount deducted to the relevant Governmental Authority in
accordance with applicable law.

                 (b)  In addition the Borrower shall pay any Other Taxes to the
relevant Governmental Authority in accordance with applicable law.

                 (c)  The Borrower shall indemnify each Vendor Lender within 10
days after written demand therefor, for the full amount of any Indemnified
Taxes or Other Taxes (including Indemnified Taxes or Other Taxes imposed or
asserted on or attributable to amounts payable under this Section 2.15) paid by
such Vendor Lender (and any penalties, interest and reasonable expenses arising
therefrom or with respect thereto during the period prior to the Borrower
making the payment demanded under this paragraph (c)), whether or not such
Indemnified Taxes or Other Taxes were correctly or legally imposed or asserted
by the relevant Governmental Authority.  A certificate as to the amount of such
payment or liability delivered to the Borrower by a Vendor Lender shall be
conclusive absent manifest error.

                 (d)  As soon as practicable after any payment of Indemnified
Taxes or Other Taxes by the Borrower to a Governmental Authority, the Borrower
shall deliver to the Vendor Lender the original or a certified copy of a
receipt issued by such Governmental Authority evidencing such payment, a copy
of the return reporting such payment or other evidence of such payment
reasonably satisfactory to the Vendor Lender.





                   Second Secured Vendor Financing Agreement
<PAGE>   35
                                     - 30 -



                 SECTION 2.16.  Payments Generally; Pro Rata Treatment.

                 (a)  The Borrower shall make each payment required to be made
by it hereunder to each Vendor Lender (whether of principal or interest, or
under Section 2.15, or otherwise) prior to 12:00 noon, New York City time, on
the date when due, in immediately available funds, without set-off or
counterclaim.  Any amounts received after such time on any date may, in the
discretion of the respective Vendor Lenders, be deemed to have been received on
the next succeeding Business Day for purposes of calculating interest thereon.
All such payments shall be made to each Vendor Lender pursuant to instructions
delivered by such Vendor Lender to the Borrower from time to time.  If any
payment hereunder shall be due on a day that is not a Business Day, the date
for payment shall be extended to the next succeeding Business Day, and, in the
case of any payment accruing interest, interest thereon shall be payable for
the period of such extension.  All payments hereunder shall be made in U.S.
dollars.

                 (b)  This paragraph (b) has been intentionally left blank.

                 (c)  Except to the extent otherwise provided herein:  (i) each
borrowing of Tranche D Loans from the Vendor Lenders under Section 2.01 hereof
shall be made from the Vendor Lenders, and each termination or reduction of the
amount of the Tranche D Commitments under Section 2.03 hereof shall be applied
to the Tranche D Commitments of the Vendor Lenders, pro rata according to the
amounts of their respective Tranche D Commitments; (ii) each payment or
prepayment by the Borrower of principal of Tranche D Loans shall be made for
account of the Vendor Lenders pro rata in accordance with the respective unpaid
principal amounts of the Tranche D Loans held by them; and (iii) each payment
by the Borrower of interest on Tranche D Loans shall be made for account of the
Vendor Lenders pro rata in accordance with the amounts of interest on such
Tranche D Loans then due and payable to the Vendor Lenders.

                 (d)  If, at any time after the occurrence and during the
continuance of an Event of Default hereunder or under the Credit Agreement, any
Vendor Lender shall, by exercising any right of set-off or counterclaim or
otherwise (including through voluntary prepayment by the Restricted Companies,
or through the exercise of any remedies under, or payments made pursuant to,
the Restricted Company Guarantee and Security Agreement), obtain payment in
respect of any principal of or interest on any of its Tranche D Loans resulting
in such Vendor Lender receiving payment of a greater proportion of the
aggregate principal amount of its Tranche D Loans and accrued interest thereon
than the proportion of such amounts received by the other Vendor Lenders, then
the Vendor Lender receiving such greater proportion shall purchase (for cash at
face value) participations in the Tranche D Loans of the other Vendor Lenders
to the extent necessary so that the benefit of such payments shall be shared by
all Vendor Lenders ratably in accordance with the aggregate





                   Second Secured Vendor Financing Agreement
<PAGE>   36
                                     - 31 -



amount of principal of and accrued interest on their respective Tranche D
Loans; provided that (i) if any such participations are purchased and all or
any portion of the payment giving rise thereto is recovered, such
participations shall be rescinded and the purchase price restored to the extent
of such recovery, without interest, and (ii) the provisions of this paragraph
shall not be construed to apply to any payment obtained by a Vendor Lender as
consideration for the assignment of or sale of a participation in any of its
Tranche D Loans to any assignee or participant, other than to any Credit Party
or any subsidiary or Affiliate thereof (as to which the provisions of this
paragraph shall apply).  The Borrower consents to the foregoing and agrees, to
the extent it may effectively do so under applicable law, that any Vendor
Lender acquiring a participation pursuant to the foregoing arrangements may
exercise against the Borrower rights of set-off and counterclaim with respect
to such participation as fully as if such Vendor Lender were a direct creditor
of the Borrower in the amount of such participation.


                                  ARTICLE III

                                Guarantee by NCI

                 Section 3.01.  The Guarantee.  NCI hereby guarantees to each
Vendor Lender and its successors and assigns the prompt payment in full when
due (whether at stated maturity, by acceleration or otherwise) of the principal
of and interest on the Tranche D Loans made by such Vendor Lender to the
Borrower and all other amounts from time to time owing to the Vendor Lenders by
the Borrower hereunder or under any other Second Secured Loan Document, in each
case strictly in accordance with the terms thereof (such obligations being
herein collectively called the "Guaranteed Obligations").  NCI hereby further
agrees that if the Borrower shall fail to pay in full when due (whether at
stated maturity, by acceleration or otherwise) any of the Guaranteed
Obligations, NCI will promptly pay the same, without any demand or notice
whatsoever, and that in the case of any extension of time of payment or renewal
of any of the Guaranteed Obligations, the same will be promptly paid in full
when due (whether at extended maturity, by acceleration or otherwise) in
accordance with the terms of such extension or renewal.

                 Section 3.02.  Obligations Unconditional.  The obligations of
NCI under Section 3.01 are absolute and unconditional irrespective of the
value, genuineness, validity, regularity or enforceability of this Agreement,
the other Second Secured Loan Documents or any other agreement or instrument
referred to herein or therein, or any substitution, release or exchange of any
other guarantee of or security for any of the Guaranteed Obligations, and, to
the fullest extent permitted by applicable law, irrespective of any other
circumstance whatsoever that might otherwise constitute a legal or equitable
discharge or defense of a surety or guarantor, it being the intent of this
Section 3.02 that the obligations of NCI hereunder shall be absolute and
unconditional under any and all circumstances.  Without





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limiting the generality of the foregoing, it is agreed that the occurrence of
any one or more of the following shall not alter or impair the liability of NCI
hereunder which shall remain absolute and unconditional as described above:

                          (i)  at any time or from time to time, without notice
         to NCI, the time for any performance of or compliance with any of the
         Guaranteed Obligations shall be extended, or such performance or
         compliance shall be waived;

                          (ii)  any of the acts mentioned in any of the
         provisions hereof or of the other Second Secured Loan Documents or any
         other agreement or instrument referred to herein or therein shall be
         done or omitted;

                          (iii)  the maturity of any of the Guaranteed
         Obligations shall be accelerated, or any of the Guaranteed Obligations
         shall be modified, supplemented or amended in any respect, or any
         right hereunder or under the other Second Secured Loan Documents or
         any other agreement or instrument referred to herein or therein shall
         be waived or any other guarantee of any of the Guaranteed Obligations
         or any security therefor shall be released or exchanged in whole or in
         part or otherwise dealt with; or

                          (iv)  any lien or security interest granted to, or in
         favor of, the Collateral Agent or any Vendor Lender as security for
         any of the Guaranteed Obligations shall fail to be perfected.

NCI hereby expressly waives diligence, presentment, demand of payment, protest
and all notices whatsoever, and any requirement that any Vendor Lender exhaust
any right, power or remedy or proceed against the Borrower hereunder or under
the other Second Secured Loan Documents or any other agreement or instrument
referred to herein or therein, or against any other Person under any other
guarantee of, or security for, any of the Guaranteed Obligations.

                 Section 3.03.  Reinstatement.  The obligations of NCI under
this Article III shall be automatically reinstated if and to the extent that
for any reason any payment by or on behalf of the Borrower in respect of the
Guaranteed Obligations is rescinded or must be otherwise restored by any holder
of any of the Guaranteed Obligations, whether as a result of any proceedings in
bankruptcy or reorganization or otherwise, and NCI agrees that it will
indemnify each Vendor Lender on demand for all reasonable costs and expenses
(including fees of counsel) incurred by such Vendor Lender in connection with
such rescission or restoration, including any such costs and expenses incurred
in defending against any claim alleging that such payment constituted a
preference, fraudulent transfer or similar payment under any bankruptcy,
insolvency or similar law.





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                                     - 33 -



                 Section 3.04.  Subrogation.  NCI hereby waives all rights of
subrogation or contribution, whether arising by contract or operation of law
(including, without limitation, any such right arising under the Federal
Bankruptcy Code of 1978, as amended) or otherwise by reason of any payment by
it pursuant to the provisions of this Article III and further agrees with the
Borrower for the benefit of each of its creditors (including, without
limitation, each Vendor Lender) that any such payment by it shall constitute a
contribution of capital by NCI to the Borrower.

                 Section 3.05.  Remedies.  NCI agrees that, as between NCI and
the Vendor Lenders, the obligations of the Borrower hereunder may be declared
to be forthwith due and payable as provided in Article VIII (and shall be
deemed to have become automatically due and payable in the circumstances
provided in Article VIII) for purposes of Section 3.01 notwithstanding any
stay, injunction or other prohibition preventing such declaration (or such
obligations from becoming automatically due and payable) as against the
Borrower and that, in the event of such declaration (or such obligations being
deemed to have become automatically due and payable), such obligations (whether
or not due and payable by the Borrower) shall forthwith become due and payable
by NCI for purposes of Section 3.01.

                 Section 3.06.  Instrument for the Payment of Money.  NCI
hereby acknowledges that the guarantee in this Article III constitutes an
instrument for the payment of money, and consents and agrees that any Vendor
Lender, at its sole option, in the event of a dispute by NCI in the payment of
any moneys due hereunder, shall have the right to bring motion-action under New
York CPLR Section 3213.

                 Section 3.07.  Continuing Guarantee.  The guarantee in this
Article III is a continuing guarantee, and shall apply to all Guaranteed
Obligations whenever arising.


                                   ARTICLE IV

                         Representations and Warranties

                 NCI and each Restricted Company represents and warrants to the
Vendor Lenders, as to itself and each of its subsidiaries, that:

                 SECTION 4.01.  Organization; Powers.  NCI is duly organized,
validly existing and in good standing under the laws of the State of Delaware.
Each of the Restricted Companies is duly organized, validly existing and in
good standing under the laws of the jurisdiction of its organization.  Each
Credit Party has all requisite power and authority under their respective
organizational documents to carry on its business as now conducted and, except
where the failure to do so, individually or in the aggregate, could not





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                                     - 34 -



reasonably be expected to result in a Material Adverse Effect, is qualified to
do business in, and is in good standing in, every jurisdiction where such
qualification is required.

                 SECTION 4.02.  Authorization; Enforceability.  The
Transactions are within the corporate power of each Credit Party and have been
duly authorized by all necessary corporate and, if required, stockholder action
on the part of such Credit Party.  This Agreement has been duly executed and
delivered by each Credit Party and constitutes a legal, valid and binding
obligation of such Credit Party, enforceable in accordance with its terms,
subject to applicable bankruptcy, insolvency, reorganization, moratorium or
other laws affecting creditors' rights generally and subject to general
principles of equity, regardless of whether considered in a proceeding in
equity or at law.

                 SECTION 4.03.  Governmental Approvals; No Conflicts.  The
Transactions (a) do not require any consent or approval of, registration or
filing with, or any other action by, any Governmental Authority, (b) will not
violate any applicable law, policy or regulation or the charter, by-laws or
other organizational documents of any Credit Party or any order of any
Governmental Authority, (c) will not violate or result in a default under any
indenture, agreement or other instrument binding upon any Credit Party, or any
of its assets, or give rise to a right thereunder to require any payment to be
made by any Credit Party, and (d) except for the Liens created by the Security
Documents, will not result in the creation or imposition of any Lien on any
asset of the Credit Parties.

                 SECTION 4.04.  Financial Condition; No Material Adverse
Change.

                 (a)  The Credit Parties have heretofore delivered to the
Vendor Lenders the following financial statements:

                          (i)  the audited consolidated balance sheet and
         statements of operations, changes in stockholders' equity and cash
         flows of NCI and its subsidiaries as of and for the fiscal year ended
         December 31, 1996, reported on by Deloitte & Touche LLP, independent
         public accountants; and

                          (ii)  the unaudited consolidated balance sheet and
         statements of changes in stockholders' equity and cash flows of NCI
         and its subsidiaries as of and for the three-month period ended June
         30, 1997, together with the unaudited consolidated statements of
         operations for such period and for the fiscal quarter ended June 30,
         1997, in each case certified by a Financial Officer of NCI.

Such financial statements present fairly, in all material respects, the
consolidated financial position and results of operations and cash flows of NCI
and its subsidiaries, and the pro forma combined financial position and results
of operations and cash flows of the Restricted Companies, as of such dates and
for such periods in accordance with GAAP, subject to year-





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                                     - 35 -



end audit adjustments and the absence of footnotes in the case of the
statements as at and for the fiscal quarter and three-month period ended June
30, 1997.

                 (b)  Since June 30, 1997, there has been no material adverse
change in the business, assets, operations, prospects or condition, financial
or otherwise, of NCI and its subsidiaries, or of the Restricted Companies, in
each case taken as a whole.

                 (c)  None of the Credit Parties has on the date hereof any
contingent liabilities, liabilities for taxes, unusual forward or long-term
commitments or unrealized or anticipated losses from any unfavorable
commitments in each case that are material, except as referred to or reflected
or provided for in the balance sheets as at June 30, 1997 referred to above or
pursuant to the Vendor Equipment Agreements.

                 SECTION 4.05.  Representations in Vendor Financing Agreement.
Each of the representations and warranties set forth in Sections 4.05 through
4.17, inclusive, of the Vendor Financing Agreement is true and correct on the
date hereof as if incorporated by reference herein in full and made on and as
of the date (or, if any such representation or warranty is expressly stated to
have been made as of a specific date or as of the date of the Vendor Financing
Agreement, such representation and warranty is true and correct as of such
specific date or the date of the Vendor Financing Agreement as applicable).


                                   ARTICLE V

                                   Conditions

                 SECTION 5.01.  Effective Date.  The obligations of the Vendor
Lenders to make Tranche D Loans hereunder shall not become effective until the
date on which each of the following conditions is satisfied (or waived in
accordance with Section 10.02):

                 (a)  Counterparts of Agreement.  Each Vendor Lender (or its
         counsel) shall have received from each Credit Party either (i) a
         counterpart of this Agreement signed on behalf of such Credit Party or
         (ii) written evidence satisfactory to such Vendor Lender (which may
         include telecopy transmission of a signed signature page of this
         Agreement) that such Credit Party has signed a counterpart of this
         Agreement.

                 (b)  Opinion of Counsel to Credit Parties.  Each Vendor Lender
         (or its counsel) shall have received a favorable written opinion
         (addressed to such Vendor Lender and dated the Effective Date) of
         Jones, Day, Reavis & Pogue, counsel to the Credit Parties, covering
         such matters relating to the Credit Parties, this Agreement, the other
         Second Secured Loan Documents or the Transactions as the Required
         Vendor Lenders shall request (and each Credit Party hereby requests
         such counsel to





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                                     - 36 -



         deliver such opinion).  To the extent deemed appropriate by the
         Restricted Companies, internal corporate matters in such opinion (such
         as due incorporation and the like) may be rendered in a separate
         opinion from the General Counsel of NCI.

                 (c)  Intentionally Left Blank.  This paragraph (c) has been
         intentionally left blank.

                 (d)  Intentionally Left Blank.  This paragraph (d) has been
         intentionally left blank.

                 (e)  Corporate Matters.  Each Vendor Lender (or its counsel)
         shall have received such documents and certificates as such Vendor
         Lender or its counsel may reasonably request relating to the
         organization, existence and good standing of each Credit Party, the
         authorization of the Transactions and any other legal matters relating
         to the Credit Parties, this Agreement, the other Second Secured Loan
         Documents or the Transactions, all in form and substance reasonably
         satisfactory to such Vendor Lender and its counsel.

                 (f)  Financial Officer Certificate.  Each Vendor Lender (or
         its counsel) shall have received a certificate, dated the Effective
         Date and signed by the President, a Vice President or a Financial
         Officer of the Borrower, confirming compliance with the conditions set
         forth in paragraphs (a) through (d) of Section 5.02.

                 (g)  Notes.  Each Vendor Lender (or its counsel) shall have
         received for such Vendor Lender, a duly completed and executed
         promissory note.

                 (h)  Amendment No. 2 to Restricted Company Guarantee and
         Security Agreement.  The Collateral Agent (or "Special Counsel" under
         the Credit Agreement) shall have received from each Restricted Company
         a counterpart of Amendment No. 2 to the Restricted Company Guarantee
         and Security Agreement, substantially in the form of Exhibit C-2,
         signed on behalf of such Restricted Company.

                 (i)  Intentionally Left Blank.  This paragraph (i) has been
         intentionally left blank.

                 (j)  Intentionally Left Blank.  This paragraph (j) has been
         intentionally left blank.

                 (k)  Second Secured Intercreditor and Collateral Agency
         Agreement.  Each Vendor Lender (or its counsel) shall have received
         from each Restricted Company and the Administrative Agent a
         counterpart of the Second Secured Intercreditor and Collateral Agency
         Agreement signed on behalf of such party.





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                                     - 37 -




                 (l)  Consents under Credit Agreement and Vendor Financing
         Agreement.  Each Vendor Lender shall have received evidence
         satisfactory in form and substance to it that a majority of the
         parties to the Credit Agreement and Vendor Financing Agreement shall
         have consented to this Agreement and to the transactions contemplated
         hereby.

Each Vendor Lender shall notify the Borrower of the Effective Date, and such
notice shall be conclusive and binding.  Notwithstanding the foregoing, the
obligations of the Vendor Lenders to make Tranche D Loans hereunder shall not
become effective unless each of the foregoing conditions is satisfied (or
waived pursuant to Section 10.02) at or prior to 3:00 p.m., New York City time,
on August 29, 1997 (and, in the event such conditions are not so satisfied or
waived, the Tranche D Commitments shall terminate at such time).

                 SECTION 5.02.  Each Tranche D Loan.  The obligation of each
Vendor Lender to make a Tranche D Loan on the occasion of any Borrowing is
subject to the satisfaction of the following conditions:

                 (a)  Representations and Warranties.  The representations and
         warranties of each Credit Party set forth in this Agreement and the
         other Second Secured Loan Documents shall be true and correct on and
         as of the date of such Borrowing both before and after giving effect
         thereto and to the use of the proceeds thereof (or, if any such
         representation or warranty is expressly stated to have been made as of
         a specific date, such representation or warranty shall be true and
         correct as of such specific date).

                 (b)  No Defaults.  At the time of and immediately after giving
         effect to such Borrowing no Default shall have occurred and be
         continuing.

                 (c)  Public Note Indenture Compliance.  The Borrower shall
         have delivered to each Vendor Lender a certificate of a Financial
         Officer demonstrating that one of the following shall be true: (i)
         after giving effect to such Borrowing, the aggregate amount of all
         outstanding Tranche D Loans, and Indebtedness under the Vendor
         Financing Agreement, and any other Indebtedness of NCI and its
         subsidiaries that utilizes the exceptions referred to in the
         definition of "Permitted Debt Limitation" in Section 1.01, will not
         exceed the Permitted Debt Limitation or (ii) such Borrowing is
         permitted to be incurred on such date under Section 1008 of each
         Public Note Indenture (other than the January 1994 Indenture) and
         under Section 10.8 of the January 1994 Indenture.

                 (d)  Secured Indebtedness to Revenue Ratio.  After giving
         effect to such Borrowing the Secured Indebtedness to Revenue Ratio
         shall not exceed the applicable amount set forth in Section 7.08(f).





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                                     - 38 -




                 (e)  Borrowings Exceeding $100,000,000.  If after giving
         effect to such Borrowing the aggregate principal amount of Tranche D
         Loans hereunder shall exceed $100,000,000, the entire amount of the
         "Tranche E Loans" under the Credit Agreement shall have been borrowed.

                 (f)  Borrowings under Credit Agreement.  On the date of the
         Borrowing Request all amounts originally available under the Credit
         Agreement (i.e. before giving effect to "Tranche E Loans" under the
         Credit Agreement), shall have been fully borrowed and be outstanding
         (i.e. there shall be at least $1,655,000,000 outstanding under the
         Credit Agreement).

                 (g)  Borrowings under Vendor Financing Agreement.  On the date
         of the Borrowing Request all amounts available under the Vendor
         Financing Agreement (including the contemplated increase in the
         "Tranche A Commitment" thereunder), shall have been fully borrowed and
         be outstanding (i.e. there shall be at least $395,000,000 outstanding
         under the Vendor Financing Agreement).

Each Borrowing Request shall be deemed to constitute a representation and
warranty by the Borrower (both as of the date of such Borrowing Request and as
of the date of the related Borrowing) as to the matters specified in paragraphs
(a), (b), (d) and (e) of this Section 5.02.


                                   ARTICLE VI

                             Affirmative Covenants

                 Until the Tranche D Commitments have expired or been
terminated and the principal of and interest on each Tranche D Loan hereunder
shall have been paid in full, each of the Credit Parties covenants and agrees
with the Vendor Lenders that:

                 SECTION 6.01.  Financial Statements and Other Information.
NCI and the Borrower will furnish to each Vendor Lender:

                 (a)  within 120 days after the end of each fiscal year, the
         audited consolidated statements of operations, changes in
         stockholders' equity and cash flows of NCI and its subsidiaries for
         such fiscal year, and the related audited consolidated balance sheet
         for NCI and its subsidiaries as of the end of such fiscal year,
         setting forth in each case in comparative form the corresponding
         figures for the previous fiscal year, all reported on by Deloitte &
         Touche LLP, or other independent public accountants of recognized
         national standing (without a "going concern" or like qualification or
         exception and without any qualification or exception as to the scope
         of such audit), to the effect that such audited consolidated financial
         statements present fairly in all





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                                     - 39 -



         material respects the financial condition and results of operations of
         NCI and its subsidiaries on a consolidated basis in accordance with
         GAAP consistently applied;

                 (b)  within 120 days after the end of each fiscal year, the
         unaudited combined statements of operations, changes in stockholders'
         equity and cash flows of the Restricted Companies for such fiscal
         year, and the related unaudited combined balance sheet for the
         Restricted Companies as of the end of such fiscal year, setting forth
         in each case in comparative form the corresponding figures for the
         previous fiscal year, all certified by a Financial Officer of the
         Borrower as presenting fairly in all material respects the financial
         condition and results of operations of the Restricted Companies on a
         combined basis in accordance with GAAP consistently applied, which
         financial statements shall be accompanied with a reconciliation, in
         form and detail satisfactory to the Required Vendor Lenders, to the
         audited financial statements for NCI and its subsidiaries for such
         fiscal year delivered pursuant to clause (a) above;

                 (c)  within 60 days after the end of each fiscal quarter of
         each fiscal year:

                                  (i)  the consolidated statements of
                 operations of NCI and its subsidiaries (and, separately
                 stated, the combined statements of operations of the
                 Restricted Companies) for such fiscal quarter and for the then
                 elapsed portion of the fiscal year,

                                  (ii)  the consolidated statements of changes
                 in stockholders' equity and cash flows of NCI and its
                 subsidiaries (and, separately stated, the combined statements
                 of changes in stockholders' equity and cash flows of the
                 Restricted Companies) for the then elapsed portion of the
                 fiscal year and

                                  (iii)  the related consolidated balance sheet
                 for NCI and its subsidiaries (and, separately stated, the
                 related combined balance sheet for the Restricted Companies)
                 as at the end of such fiscal quarter,

         setting forth in each case in comparative form the figures for the
         corresponding period or periods of (or, in the case of the balance
         sheet, as of the end of) the previous fiscal year, all certified by a
         Financial Officer of NCI or the Borrower (as the case may be) as
         presenting fairly, in all material respects, the financial condition
         and results of operations of NCI and its subsidiaries on a
         consolidated basis (or of the Restricted Companies on a combined
         basis) in accordance with GAAP consistently applied, subject to normal
         year-end audit adjustments and the absence of footnotes;

                 (d)  concurrently with any delivery of financial statements
         under clause (a), (b) or (c) above, a certificate of a Financial
         Officer of each of NCI and the Borrower (i) certifying as to whether a
         Default has occurred and, if a Default has occurred,





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                                     - 40 -



         specifying the details thereof and any action taken or proposed to be
         taken with respect thereto, (ii) setting forth reasonably detailed
         calculations demonstrating compliance with Sections 7.01(d), 7.01(g),
         7.03(f), clauses (iv) through (viii) of 7.04(a), 7.05(c) and 7.08
         (which calculations shall include the corresponding figures for the
         most-recently ended fiscal quarter with respect to Capital
         Expenditures and Debt Service necessary to demonstrate compliance with
         said Section 7.08), (iii) setting forth the estimated amount of Net
         Cash Payments received during the most-recently ended fiscal quarter
         from Dispositions during such quarter and (iv) stating whether any
         change in GAAP or in the application thereof has occurred since the
         later of the date of the financial statements as at December 31, 1996
         referred to in Section 4.04 and the date of the last certificate
         delivered pursuant to this clause (d) and, if any such change has
         occurred, specifying the effect of such change on the financial
         statements accompanying such certificate;

                 (e)  promptly after the same become publicly available, copies
         of all periodic and other reports, proxy statements and other
         materials filed by any Credit Party with the Securities and Exchange
         Commission, or any Governmental Authority succeeding to any or all of
         the functions of said Commission, or with any national securities
         exchange, or distributed by NCI to the holders of the Public Notes or
         to its shareholders generally;

                 (f)  as soon as available and in any event within 45 days
         after the end of each fiscal quarter of each fiscal year of the
         Borrower, a report identifying any SMR License or PUC Authorization
         material to the Mobile Communications Business of the Restricted
         Companies that has been lost, surrendered or canceled during such
         period, and within 10 Business Days of the receipt by any of the
         Restricted Companies of notice that any such SMR License or PUC
         Authorization has been lost or canceled or is subject to any action
         that might reasonably be expected to cause such loss or cancellation,
         copies of any such notice accompanied by a report describing the
         measures undertaken by the Restricted Companies to prevent such loss
         or cancellation (and the anticipated impact, if any, that such loss or
         cancellation will have upon the Mobile Communications Business of the
         Restricted Companies);

                 (g)  promptly following any request therefor, such other
         information regarding the operations, business affairs and financial
         condition of any Credit Party, or compliance with the terms of this
         Agreement, as any Vendor Lender may reasonably request (including any
         information delivered by any Restricted Company to either Agent or any
         Lender under the Credit Agreement).

                 SECTION 6.02.  Notices of Material Events.  NCI and the
Borrower will furnish to each Vendor Lender prompt written notice of the
following:





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                                     - 41 -



                 (a)  the occurrence of any Default;

                 (b)  the filing or commencement of any action, suit or
         proceeding by or before any arbitrator or Governmental Authority
         against or affecting any Credit Party that, if adversely determined,
         could reasonably be expected to result in a Material Adverse Effect;

                 (c)  the occurrence of any ERISA Event that, alone or together
         with any other ERISA Events that have occurred, could reasonably be
         expected to result in liability of the Restricted Companies in an
         aggregate amount exceeding $10,000,000; and

                 (d)  any other development that results in, or could
         reasonably be expected to result in, a Material Adverse Effect.

Each notice delivered under this Section 6.02 shall be accompanied by a
statement of a Financial Officer or other executive officer of NCI or the
Borrower, as the case may be, setting forth the details of the event or
development requiring such notice and any action taken or proposed to be taken
with respect thereto.

                 SECTION 6.03.  Existence; Conduct of Business.  Each of the
Credit Parties will do or cause to be done all things necessary to preserve,
renew and keep in full force and effect its legal existence and the rights,
licenses, permits, privileges and franchises material to the conduct of its
business; provided that the foregoing shall not prohibit any merger,
consolidation, liquidation or dissolution permitted under Section 7.03.  In
that connection, each of the Restricted Companies shall take any and all
necessary and appropriate action to maintain all of the SMR Licenses and other
FCC Licenses and PUC Authorizations material to the Mobile Communications
Business of the Restricted Companies in full force and effect without adverse
modification, shall construct and operate each SMR System and other ancillary
system in compliance with applicable FCC Licenses and PUC Authorizations, and
shall otherwise comply in all material respects with the terms of all FCC
Licenses and PUC Authorizations as well as applicable laws, rules, policies,
decisions and orders of the FCC, any applicable PUC and any other Governmental
Authority, including new rules issued by the FCC with respect to RF Emissions.

                 Without limiting the generality of the foregoing, each of the
Restricted Companies will:

                          (i)  do all things necessary to maintain its
         corporate existence separate and apart from NCI and the Unrestricted
         Companies and any division thereof, including holding regular meetings
         of its shareholders and Board of Directors and maintaining appropriate
         corporate books and records (including current minute books);





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                                     - 42 -




                          (ii)  not suffer any limitation on the authority of
         its own officers and directors to conduct its business and affairs in
         accordance with their independent business judgment, or authorize or
         suffer any Person other than its own officers to conduct its business
         and affairs in accordance with their independent business judgment, or
         authorize or suffer any Person other than its own officers and
         directors to act on its behalf with respect to matters (other than
         matters customarily delegated to others under power of attorney) for
         which a corporation's own officers and directors would customarily be
         responsible;

                          (iii)  maintain the operations of the Restricted
         Companies separate and apart from the operations of NCI and the
         Unrestricted Companies, including (A) following customary corporate
         formalities, (B) identifying separately all of its assets from those
         of NCI and the Unrestricted Companies, (C) when dealing with creditors
         of the Restricted Companies, or supplying financial information to
         creditors of the Restricted Companies, identifying the respective
         Restricted Company as a separate legal entity, (D) if NCI shall issue
         account statements on behalf of the Restricted Companies to customers
         of the Restricted Companies at any time after the date 120 days
         following the Effective Date, identifying that such statements are
         being delivered "for the respective operating companies" (or words of
         similar import) rendering the services covered by such statements and
         (E) accounting for and managing all of its liabilities separately from
         those of NCI and the Unrestricted Companies, including payment by it
         of all payroll and other administrative expenses and taxes (except as
         contemplated by the Overhead Services Agreement and the Tax Sharing
         Agreement) from its own assets; and

                          (iv)  not commingle its funds with those of NCI or
         any Unrestricted Company or use its funds for other than in the
         business conducted by the Restricted Companies.

                 SECTION 6.04.  Payment of Obligations.  Each of the Credit
Parties will pay its obligations, including Tax liabilities, that, if not paid,
could result in a Material Adverse Effect before the same shall become
delinquent or in default, except where (a) the validity or amount thereof is
being contested in good faith by appropriate proceedings, (b) such Credit Party
has set aside on its books adequate reserves with respect thereto in accordance
with GAAP and (c) the failure to make payment pending such contest could not
reasonably be expected to result in a Material Adverse Effect.

                 SECTION 6.05.  Maintenance of Properties; Insurance.  Each of
the Credit Parties will (a) keep and maintain all property material to the
conduct of its business in good working order and condition, ordinary wear and
tear excepted, and (b) maintain, with financially sound and reputable insurance
companies, insurance in such amounts and against





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                                     - 43 -



such risks as are customarily maintained by companies engaged in the same or
similar businesses operating in the same or similar locations.

                 SECTION 6.06.  Books and Records; Inspection Rights.  Each of
the Credit Parties will keep proper books of record and account in which full,
true and correct entries are made of all dealings and transactions in relation
to its business and activities.  Each of the Credit Parties will permit any
representatives designated by any Vendor Lender, upon reasonable prior notice,
to visit and inspect its properties, to examine and make extracts from its
books and records, and to discuss its affairs, finances and condition with its
officers and independent accountants, all at such reasonable times and as often
as reasonably requested.

                 SECTION 6.07.  Fiscal Year.  The Credit Parties will not
change the last day of their fiscal year from December 31 of each year, or the
last days of the first three fiscal quarters in each of their fiscal years from
March 31, June 30 and September 30 of each year, respectively.

                 SECTION 6.08.  Compliance with Laws.  Each of the Credit
Parties will comply with all laws, rules, regulations and orders of any
Governmental Authority applicable to it or its property, except where the
failure to do so, individually or in the aggregate, could not reasonably be
expected to result in a Material Adverse Effect.

                 SECTION 6.09.  Use of Proceeds.  The proceeds of the Tranche D
Loans hereunder will be used exclusively for purchasing wireless communications
fixed network equipment, software or related goods and services manufactured or
supplied by or through Motorola, and the transportation, sales and use taxes,
installation, testing and optimization costs related to such equipment or
software (each such use of proceeds being herein called a "Qualified
Purchase"), provided that all such proceeds are deployed by the Restricted
Companies within the United States of America.  If the Borrower shall have
initially elected to pay cash for a Qualified Purchase, it may refund such
payment of cash through a Borrowing of Tranche D Loans hereunder, so long as
the sum of (A) the aggregate outstanding amount of Tranche D Loans hereunder
plus (B) the aggregate outstanding amount of Loans under the Vendor Financing
Agreement minus the amount of such Loans outstanding as of March 26, 1997,
shall not exceed the aggregate amount of such Qualified Purchases since March
26, 1997.

                 SECTION 6.10.  Hedging Agreements.  For a period of at least
three years measured from September 27, 1996, the Borrower will maintain in
full force and effect one or more Hedging Agreements with one or more of the
Lenders (and/or with a bank or other financial institution having capital,
surplus and undivided profits of at least $500,000,000), that satisfy the
following requirements:





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                 (a)  the notional principal amount of such Hedging
         Agreement(s), together with the aggregate principal amount of
         Indebtedness of NCI and the Restricted Companies bearing interest at a
         fixed rate, shall be at least equal to 50% of the sum of the Tranche D
         Commitments hereunder and all other Indebtedness of NCI and the
         Restricted Companies outstanding on September 27, 1996; and

                 (b)  each such Hedging Agreement shall enable the Restricted
         Companies, as at any date, to protect themselves against three-month
         London interbank offered rate fluctuations at rates, and in a manner,
         reasonably satisfactory to the "Required Lenders" under the Credit
         Agreement.

                 SECTION 6.11.  Certain Obligations Respecting Subsidiaries and
Collateral Security.

                 (a)  Guarantors.  In the event that any Restricted Company
shall form or acquire any new subsidiary after the date hereof (and in the
event that NCI shall form or acquire any new subsidiary after the date hereof
constituting a "Restricted Subsidiary" under and as defined in the Public Note
Indentures or shall designate an existing Unrestricted Subsidiary as a
"Restricted Subsidiary" under and as defined in the Public Note Indentures),
such Credit Party will, within five Business Days of such formation or
acquisition, cause such new subsidiary (or such "Restricted Subsidiary"):

                          (i)  to execute and deliver to the Collateral Agent a
         Joinder Agreement (and thereby become a party to this Agreement, as a
         "Restricted Company" hereunder, and the Restricted Company Guarantee
         and Security Agreement and Second Secured Intercreditor and Collateral
         Agency Agreement, as a "Guarantor" thereunder) and to pledge and grant
         a security interest in its property pursuant to the Restricted Company
         Guarantee and Security Agreement to the Collateral Agent for the
         benefit of the Vendor Lenders, the Vendors and the Lenders;

                          (ii)  to take such action (including delivering such
         shares of stock and executing and delivering such Uniform Commercial
         Code financing statements) as shall be necessary to create and perfect
         valid and enforceable first priority Liens consistent with the
         provisions of the Security Documents, on substantially all of the
         shares of stock and property of such new subsidiary (or such
         "Restricted Subsidiary") under the Restricted Company Guarantee and
         Security Agreement; and

                          (iii)  to deliver such proof of corporate action,
         incumbency of officers and other documents (including, opinions of
         counsel, but only in the case of any such subsidiary, or group of
         subsidiaries, that in the aggregate have assets with a fair market
         value exceeding $10,000,000 and then only to the extent requested by
         any Vendor Lender) as is consistent with those delivered by each
         Restricted Company





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                                     - 45 -



         pursuant to Section 5.01 upon the Effective Date or as any Vendor
         Lender or the Collateral Agent shall have requested.

Notwithstanding the foregoing, no subsidiary that is an "Unrestricted
Subsidiary" under and as defined in the Public Note Indentures shall be
designated as a "Restricted Subsidiary" under and as defined in the Public Note
Indentures unless immediately prior thereto and after giving effect thereto, no
Default shall have occurred and be continuing.

                 (b)  Ownership of Subsidiaries.  Each Restricted Company will
take such action from time to time as shall be necessary to ensure that the
percentage of the equity capital of any class or character owned by it in any
subsidiary on the date hereof (or, in the case of any newly formed or newly
acquired subsidiary, on the date of formation or acquisition) is not at any
time decreased, other than by reason of transfers to another Restricted
Company.  In the event that any additional shares of stock shall be issued by
any subsidiary of any Restricted Company, the respective Restricted Company
shall forthwith deliver to the Collateral Agent pursuant to the Restricted
Company Guarantee and Security Agreement the certificates evidencing such
shares of stock, accompanied by undated stock powers executed in blank and to
take such other action as the Collateral Agent shall request to perfect the
security interest created therein pursuant to the Restricted Company Guarantee
and Security Agreement.

                 (c)  Regulatory Matters.  If after the date hereof there shall
be a change in law, or the rules or regulations of the FCC or applicable to any
PUC Authorization, the effect of which is to permit the granting of a security
interest in the FCC Licenses or such PUC Authorization, the Restricted
Companies will, within five Business Days after request therefor by the
Collateral Agent (or the Required Vendor Lenders through the Collateral Agent)
execute and deliver all such instruments and documents, and take such other
actions, as shall be necessary or desirable, or that the Collateral Agent (or
the Required Vendor Lenders) may reasonably request, in order to create and
perfect (or to confirm the creation and perfection of) a security interest in
the FCC Licenses or such PUC Authorization.

                 (d)  Real Property Interests.  Within 120 days after the end
of each fiscal year of the Borrower, the Restricted Companies will deliver to
the Collateral Agent a revised list, as of the last day of such fiscal year, of
the information heretofore delivered pursuant to Section 4.05(b) of the Vendor
Financing Agreement, setting forth all of the real property interests owned or
leased by the Restricted Companies as at such date, such list to be in the same
form and detail, and otherwise to be reasonably satisfactory, to the Collateral
Agent.  In addition, within 60 days after the end of each fiscal quarter of
each fiscal year of the Borrower, the Restricted Companies will deliver to the
Collateral Agent a supplement, as of the last day of such fiscal quarter, with
respect to the information heretofore delivered pursuant to said Section
4.05(b), setting forth any additional real property interests owned or leased
by the Restricted Companies since the date of the most recent list or
supplement, as





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<PAGE>   51
                                     - 46 -



the case may be, delivered pursuant to said Section 4.05(b) or this paragraph
(d), such list to be in the same form and detail, and otherwise to be
reasonably satisfactory, to the Collateral Agent.

                 (e)  License Information.  Within 120 days after the end of
each fiscal year of the Borrower, the Restricted Companies will deliver to the
Administrative Agent (and, upon request by a Vendor Lender, to such Vendor
Lender) under the Credit Agreement a revised list, as of the last day of such
fiscal year, of the information heretofore delivered pursuant to Section
4.13(a) of the Vendor Financing Agreement, setting forth all of the SMR
Licenses and other FCC Licenses or PUC Authorizations held or managed by any
Restricted Company as at such date, such list to be in the same form and
detail, and otherwise to be reasonably satisfactory, to the Administrative
Agent.  In addition, within 60 days after the end of each fiscal quarter of
each fiscal year of the Borrower, the Restricted Companies will deliver to the
Administrative Agent under the Credit Agreement a supplement, as of the last
day of such fiscal quarter, with respect to the information heretofore
delivered pursuant to said Section 4.13(a), setting forth any additional SMR
Licenses and other FCC Licenses or PUC Authorizations held or managed by any
Restricted Company since the date of the most recent list or supplement, as the
case may be, delivered pursuant to said Section 4.13(a) or this paragraph (e),
such list to be in the same form and detail, and otherwise to be reasonably
satisfactory, to the Administrative Agent.

                 SECTION 6.12.  Planned Option Issuances.  NCI will,
immediately upon receipt thereof, contribute to one or more of the Restricted
Companies, as additional equity capital in respect of the common stock of the
Restricted Companies, any proceeds received by NCI after the date hereof from
Planned Option Issuances.  In addition, NCI will from time to time make such
contributions of capital to the Restricted Companies as shall be necessary so
that the aggregate amount of Contributed Capital (i) as at July 31, 1997 shall
be at least equal to $232,000,000, (ii) as at July 31, 1998 shall be at least
equal to $550,000,000 and (iii) as at December 31, 1999 shall at least equal to
$1,100,000,000.


                                  ARTICLE VII

                               Negative Covenants

                 Until the Tranche D Commitments have expired or terminated and
the principal of and interest on each Tranche D Loan hereunder have been paid
in full, the Credit Parties covenant and agree with the Vendor Lenders that:

                 SECTION 7.01.  Indebtedness.  No Credit Party will create,
incur, assume or permit to exist any Indebtedness, except:





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                                     - 47 -



                 (a)  Indebtedness created hereunder;

                 (b)  Indebtedness of the Borrower to the Lenders under the
         Credit Agreement in an aggregate principal amount not exceeding
         $1,905,000,000 at any time and to the Vendors under the Vendor
         Financing Agreement in an aggregate principal amount not exceeding
         $395,000,000 at any time, provided that if, after obtaining any
         necessary consent of the Lenders under the Credit Agreement and of the
         Required Vendor Lenders, the aggregate principal amount of
         Indebtedness under the Credit Agreement and the Vendor Financing
         Agreement shall be increased to an amount greater than $2,300,000,000
         then unless the Required Vendor Lenders shall have consented
         hereunder, either

                                  (i)  the Borrower shall have prepaid Tranche
                 D Loans hereunder (or, if no Tranche D Loans are outstanding
                 hereunder, the Tranche D Commitments hereunder shall have been
                 reduced), in an amount equal to such excess over
                 $2,300,000,000 or

                                  (ii)  the Security Documents, the
                 Intercreditor and Collateral Agency Agreement and the Second
                 Secured Intercreditor and Collateral Agency Agreement shall
                 each have been amended to the extent necessary to provide that
                 a portion of the Tranche D Loans hereunder equal to such
                 excess over $2,300,000,000 shall be secured equally and
                 ratably with such Indebtedness under the Credit Agreement and
                 the Vendor Financing Agreement and shall no longer be subject
                 to the provisions of the Second Secured Intercreditor and
                 Collateral Agency Agreement;

                 (c)  Indebtedness of the Credit Parties existing on September
         27, 1996 and set forth in Schedule 7.01 to the Vendor Financing
         Agreement and,

                                  (i)  in the case of the Public Notes,
                 extensions, renewals and refinancings thereof, so long as (x)
                 any such extension, renewal and refinancing does not increase
                 the outstanding stated principal amount of the Public Notes
                 being extended, renewed or refinanced, (y) the maturity date
                 of such extension, renewal or refinancing is later than the
                 maturity date of the Public Notes being extended, renewed or
                 refinanced and (z) the terms and conditions of such extension,
                 renewal or refinancing (other than in respect of interest,
                 which shall not be restricted), are no less favorable to NCI,
                 the Restricted Companies, the Vendor Lenders, the Vendors, the
                 Lenders, and the Agents than the terms and conditions of the
                 January 1994 Indenture and the Public Notes issued thereunder;





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                                     - 48 -



                                  (ii)  in the case of any such Indebtedness of
                 the Restricted Companies, extensions, renewals and
                 refinancings thereof, so long as (w) such extension, renewal
                 and refinancing does not increase the outstanding principal
                 amount of the Indebtedness being extended, renewed or
                 refinanced, (x) the Average Life to Maturity of the
                 Indebtedness so extended, renewed or refinanced shall not be
                 shorter than the Average Life to Maturity of the Indebtedness
                 being extended, renewed or refinanced, (y) at the time of such
                 extension, renewal or refinancing, and after giving effect
                 thereto, no Default shall have occurred and be continuing and
                 (z) the terms and conditions of such Indebtedness as so
                 extended, renewed or refinanced (other than in respect of
                 interest, which shall not be restricted) are no less favorable
                 to the Restricted Companies, the Vendor Lenders, the Vendors,
                 the Lenders and the Agents than the terms and conditions of
                 this Agreement and the other Second Secured Loan Documents;

                 (d)  additional Indebtedness incurred by NCI after September
         27, 1996, provided that (i) the sum of (x) the aggregate principal
         amount of any such Indebtedness issued at par plus (y) the net
         proceeds of any such Indebtedness issued at less than par, shall not
         exceed $750,000,000, (ii) no scheduled payments, prepayments,
         redemptions or sinking fund or like payments in respect of such
         Indebtedness shall be required prior to September 30, 2003, (iii) such
         Indebtedness shall provide that interest payable in respect thereof
         shall be capitalized prior to the fifth anniversary of the date of
         incurrence of such Indebtedness and (iv) the terms and conditions of
         such Indebtedness (other than in respect of interest, which shall not
         be restricted) are no less favorable to NCI, the Restricted Companies,
         the Vendor Lenders, the Vendors, the Lenders and the Agents than the
         terms and conditions of the January 1994 Indenture and the Public
         Notes issued thereunder;

                 (e)  Indebtedness of any Restricted Company to any other
         Restricted Company;

                 (f)  this clause (f) has been intentionally left blank;

                 (g)  other Indebtedness (in addition to any amounts permitted
         pursuant to the foregoing paragraphs (a) through (f) and the following
         paragraphs (h) and (i) of this Section 7.01) of the Restricted
         Companies in an aggregate principal amount not exceeding $75,000,000
         at any time outstanding (or such greater amount to which the Required
         Parties shall have consented); and

                 (h)  other unsecured Indebtedness of NCI in an aggregate
         principal amount not exceeding $10,000,000 at any time outstanding (or
         such greater amount to which the Required Parties shall have
         consented).





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                                     - 49 -



                 (i)      Indebtedness of the Borrower (and Guarantees thereof
         by the other Restricted Companies and NCI) in an aggregate principal
         amount not exceeding $250,000,000 in respect of any "Tranche E Loans"
         and any loan made on a pro rata basis with, and on the same terms and
         conditions as, such "Tranche E Loans" (collectively, the "Additional
         Vendor Loans") as contemplated by the Term Sheet dated March 26, 1997
         between NCI and Motorola.

                 SECTION 7.02.  Liens.  NCI will not create, incur, assume or
permit to exist any Lien on any of its assets now owned or hereafter acquired
by NCI to secure Indebtedness (the "Relevant Indebtedness") without making
effective provision for securing the Indebtedness of NCI under the Vendor
Financing Agreement and under the Credit Agreement (and, if NCI shall so
determine, any other Indebtedness of NCI which is not subordinated in right of
payment to the Indebtedness hereunder) equally and ratably with the Relevant
Indebtedness as to such assets for so long as the Relevant Indebtedness shall
be so secured, and, on a junior basis, to secure the Indebtedness of NCI
hereunder.

                 No Restricted Company will create, incur, assume or permit to
exist any Lien on any of its assets except:

                 (a)  Liens created by the Security Documents securing the
         obligations of the Restricted Companies hereunder, under the Vendor
         Financing Agreement, under the Credit Agreement and under the Security
         Documents, in each case subject to the provisions of the Intercreditor
         and Collateral Agency Agreement and the Second Secured Intercreditor
         and Collateral Agency Agreement;

                 (b)  Permitted Encumbrances;

                 (c)  any Lien on any property or asset of any Restricted
         Company existing on September 27, 1996 and set forth in Schedule 4.12
         to the Vendor Financing Agreement; provided that (i) such Lien shall
         not apply to any other property or asset of any Restricted Company and
         (ii) such Lien shall secure only those obligations that it secures on
         September 27, 1996 (and extensions, renewals and refinancings thereof
         that comply with the requirements of Section 7.01(c));

                 (d)  Liens securing judgments for the payment of money in an
         amount not resulting (whether immediately or with the passage of time)
         in an Event of Default under clause (k) of Article VIII;

                 (e)  any Lien existing on any property or asset prior to the
         acquisition thereof by a Restricted Company or existing on any
         property or asset of any Person that becomes a subsidiary of a
         Restricted Company after September 27, 1996 prior to the time such
         Person becomes such a subsidiary; provided that (i) such Lien is not
         created





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                                     - 50 -



         in contemplation of or in connection with such acquisition or such
         Person becoming a subsidiary, as the case may be, (ii) such Lien shall
         not apply to any other property or assets of any Restricted Company
         and (iii) such Lien shall secure only Indebtedness in existence at the
         time of such acquisition, and that is permitted under Section 7.01(g),
         and no other Indebtedness or obligations; and

                 (f)  Liens on fixed or capital assets acquired, constructed or
         improved by the Restricted Companies; provided that (i) such Liens
         secure Indebtedness permitted under Section 7.01(g), (ii) such Liens
         and the Indebtedness secured thereby are incurred prior to or within
         90 days after such acquisition or the completion of such construction
         or improvement, (iii) the Indebtedness secured thereby does not exceed
         the cost of acquiring, constructing or improving such fixed or capital
         assets and (iv) such Liens shall not apply to any other property or
         assets of the Restricted Companies.

                 SECTION 7.03.  Fundamental Changes.  NCI shall not sell,
transfer, lease or otherwise dispose of any shares of stock of any of the
Restricted Companies owned by it.  In addition, NCI shall not merge or
consolidate with any other Person unless (i) at the time thereof, and after
giving effect thereto, no Default shall have occurred and be continuing, (ii)
either (x) NCI shall be the continuing or surviving entity or (y) the
continuing or surviving entity shall have assumed all of the obligations of NCI
hereunder pursuant to an instrument in form and substance satisfactory to each
Vendor Lender and shall have delivered such proof of corporate action,
incumbency of officers, opinions of counsel and other documents as is
consistent with those delivered by NCI pursuant to Section 5.01 upon the
Effective Date or as any Vendor Lender shall have requested and (iii) the net
worth (determined on a consolidated basis in accordance with GAAP) of the
continuing or surviving entity immediately after giving effect thereto shall be
greater than or equal to the net worth (so determined) of NCI immediately prior
to giving effect thereto.

                 No Restricted Company will merge into or consolidate with any
other Person, or permit any other Person to merge into or consolidate with it,
to the extent that any such merger or consolidation would effect a transfer of
cash or other property constituting Collateral (whether or not such cash or
other property is in the possession, or under the control, of the Collateral
Agent), or sell, transfer, lease or otherwise dispose of (in one transaction or
in a series of transactions) any cash or other property (including the stock of
any of its subsidiaries), whether now owned or hereafter acquired, constituting
Collateral (whether or not such cash or other property is in the possession, or
under the control, of the Collateral Agent), except that:

                 (a)  any Restricted Company (other than a License Company) may
         merge into the Borrower in a transaction in which the Borrower is the
         surviving corporation;





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<PAGE>   56
                                     - 51 -



                 (b)  any Restricted Company may merge into any other
         Restricted Company, provided that no such merger may involve a License
         Company, unless (x) immediately after giving effect thereto no Default
         shall have occurred and be continuing and (y) in the case of any
         License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations, the surviving entity in such merger is
         a License Company substantially all of whose assets consist of FCC
         Licenses or PUC Authorizations;

                 (c)  any Restricted Company may permit any other Person to
         merge into or consolidate with such Restricted Company to the extent
         permitted by Section 7.04(a)(viii);

                 (d)  any Restricted Company other than the Borrower may sell,
         transfer, lease or otherwise dispose of its assets to another
         Restricted Company, provided that no such transaction may involve a
         disposition of assets of any License Company unless (x) immediately
         after giving effect thereto no Default shall have occurred and be
         continuing and (y) in the case of any transfer of assets by a License
         Company substantially all of whose assets consist of FCC Licenses or
         PUC Authorizations, the acquiror of such assets (after giving effect
         to such acquisition) is a License Company substantially all of whose
         assets consist of FCC Licenses or PUC Authorizations;

                 (e)  any Restricted Company may sell, transfer, lease or
         otherwise dispose of its assets to any Person on an arms-length basis
         in the ordinary course of business;

                 (f)  any Restricted Company may sell any of its assets for
         consideration in an amount not less than the fair market value of such
         assets, provided that (A) at least 85% of such consideration is in the
         form of cash, (B) the Net Cash Payments of such sale are applied
         (prior to the Senior Termination Date) to prepay the "Loans" and
         reduce the "Commitment" under the Credit Agreement and Vendor
         Financing Agreement to the extent required under Section 2.09(b)(ii)
         thereof and (after the Senior Termination Date) to prepay the Tranche
         D Loans hereunder (or, if no Tranche D Loans are outstanding
         hereunder, to the reduction of the Tranche D Commitments hereunder),
         to the extent required by Section 2.09(b)(ii), (C) at the time of such
         sale and immediately after giving effect thereto no Default shall have
         occurred and be continuing and (D) the aggregate fair market value of
         all such assets sold by the Restricted Companies after September 27,
         1996, shall not exceed $250,000,000;

                 (g)  the Restricted Companies may dispose of assets relating
         to any Mobile Communications Business (or the capital stock of any
         Restricted Company that owns such assets), provided that:





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                                     - 52 -



                                  (i)  both immediately prior to such
                 disposition and, after giving effect thereto, no Default shall
                 have occurred and be continuing; and

                                  (ii)  such disposition is an exchange, with
                 another Person, not an Affiliate of such Restricted Company,
                 of such assets for assets of like kind owned by such Person
                 (or the capital stock, or other equity ownership interest, of
                 such Person) comprising a Mobile Communications Business, as
                 the case may be, of equal or greater value, as determined in
                 good faith by the Board of Directors of such Restricted
                 Company, provided that (x) the acquisition of assets of such
                 Person pursuant to such exchange (excluding acquisitions of
                 FCC Licenses in exchange for other FCC Licenses for the
                 purpose of enabling the Restricted Companies to create
                 contiguous blocks of spectrum covered by the SMR Licenses of
                 the Restricted Companies) shall comply with the provisions of
                 one of Section 7.04(a)(vii) or 7.04(a)(viii) and be treated as
                 an acquisition covered by said Sections and (y) the Borrower
                 shall have furnished to the Vendor Lenders, promptly following
                 request therefor, copies of such information or documents
                 relating to such disposition as any Vendor Lender shall have
                 reasonably requested.

                 SECTION 7.04.  Investments, Loans, Advances, Guarantees and
Acquisitions; Hedging Agreements.

                 (a)  No Restricted Company will purchase, hold or acquire any
capital stock, evidences of indebtedness or other securities (including any
option, warrant or other right to acquire any of the foregoing) of, make or
permit to exist any loans or advances to, or make or permit to exist any
investment or any other interest in, any other Person, or purchase or otherwise
acquire (in one transaction or a series of transactions) any assets of any
other Person constituting a business unit, if the effect of any such
transaction would be to transfer any cash or other property constituting
Collateral (whether or not such cash or other property is in the possession, or
under the control, of the Collateral Agent) from any Restricted Company to any
other Person, except:

                          (i)  Permitted Investments, and Disposition
         Investments received in connection with any Disposition permitted
         under Section 7.03(f) or any Disposition to which the Required Vendor
         Lenders shall have consented in accordance with Section 10.02, so long
         as each such Disposition Investment shall have been delivered to the
         Collateral Agent to be held as collateral security by the Collateral
         Agent pursuant to the Restricted Company Guarantee and Security
         Agreement;

                         (ii)  investments by Restricted Companies in the
         capital stock of other Restricted Companies;





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<PAGE>   58
                                     - 53 -



                      (iii)  loans or advances made by any Restricted
         Company to any other Restricted Company;

                       (iv)  investments in Affiliates (excluding
         Unrestricted Companies, as to which the provisions of clause (v) below
         shall apply) in an aggregate amount as to all Restricted Companies at
         any one time outstanding not exceeding $5,000,000, so long as both
         immediately prior to each such investment and after giving effect
         thereto, no Default shall have occurred and be continuing;

                        (v)  investments in Unrestricted Companies in an
         aggregate amount for all Restricted Companies at any one time
         outstanding not exceeding the sum of (A) $250,000,000 plus (B) the net
         aggregate amount of equity capital received after September 27, 1996,
         by the Restricted Companies in respect of shares of common stock from
         the proceeds of Qualifying Debt or Equity Issuances by NCI (other than
         from the proceeds of Planned Option Issuances), so long as both
         immediately prior to each such investment and after giving effect
         thereto, no Default shall have occurred and be continuing;

                       (vi)  acquisitions of SMR Licenses in the
         currently-planned auction of 800 Mhz spectrum by the FCC, so long as:

                          (A)  following consummation of each such acquisition,
                 (x) the Restricted Companies shall have complied with the
                 requirements of Section 7.09(b) with respect to the SMR
                 Licenses acquired in such acquisition and (y) all
                 Authorizations required by the FCC in connection with such
                 acquisition shall have been duly granted pursuant to a Final
                 Order and (if the fair market value of the SMR Licenses so
                 acquired shall exceed $10,000,000 and any Vendor Lender shall
                 have requested the same) the Vendor Lenders shall have
                 received an opinion of counsel with respect to such
                 acquisition that is satisfactory in form and substance to the
                 Required Vendor Lenders;

                          (B)  the Borrower shall have delivered to the
                 Administrative Agent a supplement to Schedule 4.13 to the
                 Credit Agreement (and, if requested by any Vendor Lender,
                 shall have delivered a copy thereof to such Vendor Lender)
                 setting forth a list of the respective SMR Licenses acquired
                 in connection with such acquisition; and

                          (C)  both immediately prior to each such acquisition
                 and after giving effect thereto, no Default shall have
                 occurred and be continuing;

                      (vii)  this clause (vii) has been intentionally left
         blank;





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                                     - 54 -



                     (viii)  acquisitions of FCC Licenses in the 800 MHz
         or 900 MHz band (other than pursuant to the auction referred to in
         clause (vi) above), and acquisitions of any Mobile Communications
         Business and the related assets of any other Person (or, if for the
         purpose of enabling the Restricted Companies to create contiguous
         blocks of spectrum covered by the SMR Licenses of the Restricted
         Companies, acquisitions of cellular telephone and other businesses),
         whether by way of purchase of assets or stock, by merger or
         consolidation or otherwise, so long as:

                          (A)  the aggregate Purchase Price for all such
                 acquisitions consummated after the Amendment No. 3 Effective
                 Date (excluding any portion thereof that shall have been paid
                 through the issuance of equity securities of NCI, and
                 excluding acquisitions pursuant to the terms of one or more
                 definitive agreements as in effect on the date hereof) shall
                 not exceed $275,000,000;

                          (B)  each such acquisition of FCC Licenses is for the
                 purpose of enabling the Restricted Companies to create
                 contiguous blocks of spectrum covered by the SMR Licenses of
                 the Restricted Companies;

                          (C)  any such acquisition of a Mobile Communications
                 Business (if by purchase of assets, merger or consolidation)
                 shall be effected in such manner so that the acquired
                 business, and the related assets, are owned by a Restricted
                 Company (which may include a new Wholly Owned Subsidiary that
                 becomes a Restricted Company pursuant to Section 6.11(a)) and,
                 if effected by merger or consolidation involving the Borrower,
                 the Borrower shall be the continuing or surviving entity;

                          (D)  any such acquisition of a Mobile Communications
                 Business (if by purchase of stock) shall be effected in such
                 manner so that the acquired entity becomes a Wholly Owned
                 Subsidiary that becomes a Restricted Company pursuant to
                 Section 6.11;

                          (E)  if the fair market value of the assets of any
                 Mobile Communications Business to be so acquired shall exceed
                 $10,000,000, the Restricted Companies shall deliver to the
                 Vendor Lenders (x) no later than five Business Days prior to
                 the consummation of each such acquisition (or such earlier
                 date as shall be five Business Days after the execution and
                 delivery thereof), executed counterparts of the respective
                 agreements or instruments pursuant to which such acquisition
                 is to be consummated (including any related management,
                 non-compete, employment, option or other material agreements),
                 any schedules to such agreements or instruments and all other
                 material ancillary documents to be executed or delivered in
                 connection therewith and





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<PAGE>   60
                                     - 55 -



                 (y) promptly following request therefor, copies of such other
                 information or documents relating to each such acquisition as
                 the Required Vendor Lenders shall have reasonably requested;

                          (F)  following consummation of each such acquisition,
                 (x) the Restricted Companies shall have complied with the
                 requirements of Section 7.09(b) with respect to any FCC
                 Licenses or PUC Authorizations acquired in such acquisition
                 and (y) all Authorizations required by the FCC in connection
                 with such acquisition shall have been duly granted pursuant to
                 a Final Order and (if the fair market value of the assets so
                 acquired shall exceed $10,000,000 and any Vendor Lender shall
                 have requested the same) the Vendor Lenders shall have
                 received an opinion of counsel with respect to such
                 acquisition that is satisfactory in form and substance to the
                 Required Vendor Lenders;

                          (G)  to the extent applicable, the Restricted
                 Companies shall have complied with the provisions of Section
                 6.11, including delivery to the Collateral Agent of (x) the
                 certificates evidencing any capital stock of a Restricted
                 Company, accompanied by undated stock powers executed in blank
                 and (y) the agreements, instruments, opinions of counsel and
                 other documents required under said Section 6.11 to be
                 delivered;

                          (H)  in the case of a transaction described in clause
                 (E) above, and upon request by the Required Vendor Lenders,
                 the Borrower shall deliver to the Administrative Agent a
                 supplement to Schedule 4.13 to the Credit Agreement (and, if
                 requested by any Vendor Lender, shall have delivered a copy
                 thereof to such Vendor Lender) setting forth a list of the
                 respective SMR Licenses, other FCC Licenses and PUC
                 Authorizations acquired in connection with such acquisition;
                 and

                          (I)  both immediately prior to each such acquisition
                 and after giving effect thereto, no Default shall have
                 occurred and be continuing; and

                          (ix)  the acquisition of FCC Licenses pursuant to an
         exchange transaction permitted under Section 7.03(g) for the purpose
         of enabling the Restricted Companies to create contiguous blocks of
         spectrum covered by the SMR Licenses of the Restricted Companies.

                 (b)  No Restricted Company will Guarantee any obligations of
any other Person, except Guarantees constituting Indebtedness permitted by
Section 7.01 and Guarantees by any Restricted Company of any other Restricted
Company.





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                                     - 56 -



                 (c)  No Restricted Company will enter into any Hedging
Agreement, other than Hedging Agreements entered into in the ordinary course of
business to hedge or mitigate risks to which the Restricted Companies are
exposed in the conduct of their business or the management of their liabilities
(including, in the case of the Borrower, the Hedging Agreements required by
Section 6.10).

                 SECTION 7.05.  Restricted Payments.  No Restricted Company
will declare or make, or agree to pay or make, directly or indirectly, any
Restricted Payment consisting of any cash or other property constituting
Collateral (whether or not such cash or other property is in the possession, or
under the control, of the Collateral Agent), except:

                 (a)  any Restricted Company may make Restricted Payments to
         the extent necessary to make required payments under the Overhead
         Services Agreement, and required tax distributions under the Tax
         Sharing Agreement;

                 (b)  so long as at the time thereof, and after giving effect
         thereto, no Default shall have occurred and be continuing, any
         Restricted Company that is a subsidiary of NCI may make Restricted
         Payments to NCI to the extent necessary to enable NCI to make
         scheduled payments of principal and interest on the Public Notes;

                 (c)  in addition to the Restricted Payments permitted under
         the foregoing clauses (a) and (b), during any fiscal year (commencing
         with Excess Cash Flow for the fiscal year ending December 31, 1999),
         any Restricted Company may make Restricted Payments, subject to the
         satisfaction of each of the following conditions on the date of such
         payment and after giving effect thereto:

                                  (i)  no Default shall have occurred and be
                 continuing;

                                  (ii)  the Total Indebtedness to Cash Flow
                 Ratio as at the last day of the fiscal quarter ending on or
                 most recently ended prior to the date of such Restricted
                 Payment shall be less than 5.00 to 1;

                                  (iii)  the aggregate amount of Restricted
                 Payments under this clause (c) made during such fiscal year
                 (the "current fiscal year") shall not exceed 50% of Excess
                 Cash Flow for the fiscal year immediately preceding the
                 current fiscal year;

                                  (iv)  the Borrower shall have delivered to
                 the Vendor Lenders, at least ten Business Days (but not more
                 than twenty Business Days) prior to the date of the proposed
                 Restricted Payment, a certificate of a Financial Officer
                 setting forth computations in reasonable detail demonstrating
                 satisfaction of the foregoing conditions as at the date of
                 such certificate; and





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<PAGE>   62
                                     - 57 -




                                  (v)  if the same shall occur after the Senior
                 Termination Date then prior to, or concurrently with, the
                 making of such Restricted Payment, the Borrower shall prepay
                 the Tranche D Loans as required by Section 2.09(b)(i); and

                 (d)  at any time prior to June 30, 1997, the Restricted
         Companies may make Restricted Payments, in cash, to NCI in an
         aggregate amount up to but not exceeding an amount equal to the
         aggregate of the "Consent Payments" as specified in the April 14,
         1997, version of the Consent Solicitation Statement (as defined in
         Amendment No. 2 hereto) to be paid to the holders of the Public Notes
         in connection with obtaining the consents of such holders to the
         Supplements to the Public Note Indentures referred to in said
         Amendment No. 2.

                 SECTION 7.06.  Transactions with Affiliates.  Except as
expressly permitted by this Agreement, no Restricted Company will sell, lease
or otherwise transfer any cash or other property constituting Collateral
(whether or not such cash or other property is in the possession, or under the
control, of the Collateral Agent) to, or purchase, lease or otherwise acquire
any property or assets from, or otherwise engage in any other transactions
with, any of its Affiliates, except (a) in the ordinary course of business at
prices and on terms and conditions not less favorable to such Restricted
Company than could be obtained on an arm's-length basis from unrelated third
parties, (b) transactions between or among the Restricted Companies not
involving any other Affiliate, (c) any Restricted Payment permitted by Section
7.05, (d) as contemplated by the Overhead Services Agreement and the Tax
Sharing Agreement and (e) pursuant to the Vendor Equipment Agreements or Vendor
Financing Agreement, provided that any amendments, modifications or supplements
to any Vendor Equipment Agreement or the Vendor Financing Agreement shall be
subject to the requirements of this Section 7.06.

                 SECTION 7.07.  Restrictive Agreements.  No Restricted Company
will directly or indirectly, enter into, incur or permit to exist any agreement
or other arrangement that prohibits, restricts or imposes any condition upon
(a) the ability of any Restricted Company to create, incur or permit to exist
any Lien upon any of its property or assets, or (b) the ability of any
Restricted Company to pay dividends or other distributions with respect to any
shares of its capital stock or to make or repay loans or advances to any
Restricted Company or to Guarantee Indebtedness of any other Restricted
Company; provided that

                          (i)  the foregoing shall not apply to restrictions
         and conditions (w) imposed by law or by this Agreement, the Vendor
         Financing Agreement, the Credit Agreement or the other Second Secured
         Loan Documents, (x) existing on September 27, 1996 identified in
         Schedule 7.07 to the Vendor Financing Agreement (but shall apply to
         any extension or renewal of, or any amendment or modification
         expanding the scope of, any such restriction or condition), (y)
         consisting of customary





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<PAGE>   63
                                     - 58 -



         restrictions on transfers of site leases (provided that, except for
         leases within the scope of the exceptions contained in Section 6.13 of
         the Restricted Company Guarantee and Security Agreement, the
         Restricted Companies agree that any such lease entered into after
         September 27, 1996 shall expressly permit the creation of a security
         interest in the rights of the respective Restricted Company party
         thereto as security for indebtedness for borrowed money, or guarantees
         thereof) or (z) contained in agreements relating to the sale of a
         Restricted Company pending such sale, provided such restrictions and
         conditions apply only to the Restricted Company or assets that are to
         be sold and such sale is permitted hereunder and

                          (ii)  clause (a) above shall not apply to (x)
         restrictions or conditions imposed by any agreement relating to
         secured Indebtedness permitted by this Agreement if such restrictions
         or conditions apply only to the property or assets securing such
         Indebtedness or (y) customary provisions in leases and other contracts
         restricting the assignment thereof.

                 SECTION 7.08.  Certain Financial and Other Covenants.

                 (a)  Total Indebtedness to Cash Flow Ratio.  NCI will not
permit the Total Indebtedness to Cash Flow Ratio at any time during any period
below to exceed the ratio set opposite such period below:

<TABLE>
<CAPTION>
                 Period                                               Ratio
                 ------                                               -----
         <S>                                                        <C>
         From September 30, 1999
           through March 30, 2000                                   15.00 to 1

         From March 31, 2000
          through March 30, 2001                                     7.50 to 1

         From March 31, 2001
          through March 30, 2002                                     6.00 to 1

         From March 31, 2002
          and at all times thereafter                                5.00 to 1
</TABLE>

                 (b)  Interest Coverage Ratio.  NCI will not permit the
Interest Coverage Ratio at any time during any period below to be less than the
ratio set opposite such period below:





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<PAGE>   64
                                     - 59 -



<TABLE>
<CAPTION>
                 Period                                               Ratio
                 ------                                               -----
         <S>                                                        <C>
         From September 30, 1999
           through March 30, 2000                                   1.10 to 1

         From March 31, 2000
          through March 30, 2001                                    1.50 to 1

         From March 31, 2001
          and at all times thereafter                               2.00 to 1
</TABLE>

                 (c)  Pro-Forma Debt Service Ratio.  NCI will not permit the
Pro-Forma Debt Service Ratio as at the last day of any fiscal quarter ending on
or after March 31, 2001 to be less than 1.00 to 1.

                 (d)  Fixed Charges Ratio.  NCI will not permit the Fixed
Charges Ratio as at the last day of any fiscal quarter ending on or after March
31, 2001 to be less than 1.00 to 1.

                 (e)  Secured Indebtedness to Cash Flow Ratio.  The Restricted
Companies will not permit the Secured Indebtedness to Cash Flow Ratio at any
time during any period below to exceed the ratio set opposite such period
below:

<TABLE>
<CAPTION>
                 Period                                               Ratio
                 ------                                               -----
         <S>                                                        <C>
         From September 30, 1999
           through March 30, 2000                                   10.00 to 1

         From March 31, 2000
          through March 30, 2001                                     5.00 to 1

         From March 31, 2001
          through March 30, 2002                                     4.00 to 1

         From March 31, 2002
          and at all times thereafter                                3.00 to 1
</TABLE>

                 (f)  Secured Indebtedness to Revenue Ratio.  The Restricted
Companies will not (i) incur any Secured Indebtedness at any time during any
period set forth below if, after giving effect thereto, the Secured
Indebtedness to Revenue Ratio shall exceed the ratio set forth opposite such
period in the Incurrence Ratio column below nor (ii) permit the aggregate





                   Second Secured Vendor Financing Agreement
<PAGE>   65
                                     - 60 -



amount of Secured Indebtedness at any time during any period set forth below to
exceed the ratio set forth opposite such period in the Maintenance Ratio column
below:

<TABLE>
<CAPTION>
                                                            Incurrence       Maintenance
               Period                                          Ratio            Ratio   
               ------                                       ----------       -----------
     <S>                                                     <C>              <C>
     From Effective Date through
       September 29, 1997                                    4.25 to 1        4.50 to 1

     From September 30, 1997
      through December 30, 1997                              3.50 to 1        3.75 to 1

     From December 31, 1997
      through March 30, 1998                                 2.75 to 1        3.00 to 1

     From March 31, 1998
      through September 29, 1999                             2.50 to 1        2.75 to 1
</TABLE>

                  (g)  Minimum Annualized Revenue.  The Restricted Companies
will not permit Annualized Revenue (adjusted as provided in the next sentence)
as at any date below to be less than the amount set opposite such date below:

<TABLE>
<CAPTION>
                 Date                                                   Amount
                 ----                                                   ------
         <S>                                                        <C>
         September 30, 1996                                         $  240,000,000
         December 31, 1996                                          $  250,000,000

         March 31, 1997                                             $  275,000,000
         June 30, 1997                                              $  300,000,000
         September 30, 1997                                         $  340,000,000
         December 31, 1997                                          $  400,000,000

         March 31, 1998                                             $  500,000,000
         June 30, 1998                                              $  650,000,000
         September 30, 1998                                         $  815,000,000
         December 31, 1998                                          $  975,000,000

         The last day in each
           fiscal quarter in 1999                                   $1,485,000,000

         The last day in each
           fiscal quarter in 2000                                   $2,150,000,000
</TABLE>





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<PAGE>   66
                                     - 61 -




For purposes of this paragraph (g), Annualized Revenue as at any date shall be
reduced, for each acquisition consummated prior to such date by any Restricted
Company the Purchase Price for which exceeds $50,000,000 (excluding, however,
any such acquisition consummated prior to September 27, 1996), by an amount
equal to the product of 4 multiplied by the revenue of the business, or
attributable to the assets, so acquired for the fiscal quarter ending on, or
most recently ended prior to, the date of such acquisition, provided that, if
at the last day of any fiscal quarter of the Restricted Companies (the "current
fiscal quarter") fewer than four complete fiscal quarters shall have elapsed
following the date of such acquisition, such product shall be further
multiplied by a fraction, the numerator of which is the number of days during
the period commencing on the date of such acquisition to but excluding the last
day of the current fiscal quarter and the denominator of which is 365.

                 (h)  Minimum Network Subscriber Units.  The Restricted
Companies will not permit the aggregate number of Network Subscriber Units
(adjusted as provided in the next sentence) as at any date below to be less
than the number set opposite such date below:

<TABLE>
<CAPTION>
                 Date                                                         Number
                 ----                                                         ------
         <S>                                                                 <C>
         September 30, 1996                                                    800,000
         December 31, 1996                                                     800,000

         March 31, 1997                                                        900,000
         June 30, 1997                                                         950,000
         September 30, 1997                                                  1,000,000
         December 31, 1997                                                   1,120,000

         March 31, 1998                                                      1,230,000
         June 30, 1998                                                       1,390,000
         September 30, 1998                                                  1,575,000
         December 31, 1998                                                   1,750,000

         The last day of each fiscal
           quarter in 1999 and 2000                                          2,250,000
</TABLE>

For purposes of this paragraph (h), Network Subscribers Units as at any date
shall be reduced, for each acquisition consummated prior to such date by any
Restricted Company the Purchase Price for which exceeds $50,000,000 (excluding,
however, any such acquisition consummated prior to September 27, 1996), by the
number or Network Subscriber Units of the business, or attributable to the
assets, so acquired on the date on which such acquisition is consummated.





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<PAGE>   67
                                     - 62 -



                 SECTION 7.09.  Lines of Business, Etc.

                 (a)  Business Activities.  No Restricted Company will engage
to any substantial extent in any line or lines of business activity other than
the Mobile Communications Business, and businesses reasonably related thereto,
provided that nothing herein shall be deemed to prohibit the Restricted
Companies from acquisitions of FCC Licenses in the 800 MHz or 900 MHz bands, or
of cellular telephone and other businesses, in each case pursuant to Section
7.04(a)(viii) for the purpose of enabling the Restricted Companies to create
contiguous blocks of spectrum covered by the SMR Licenses of the Restricted
Companies.

                 (b)  License Companies.  The Restricted Companies will not at
any time permit any FCC Licenses and PUC Authorizations (including any thereof
acquired after the date hereof, but excluding any PUC Authorizations issued by
PUC's in any jurisdiction that prohibits the actions contemplated by this
paragraph (b)) to be held by any First Tier Restricted Company, provided that
with respect to any FCC Licenses and PUC Authorizations acquired by any First
Tier Restricted Company after September 27, 1996 pursuant to an acquisition
permitted under Section 7.04, such First Tier Restricted Company will cause
such FCC Licenses and PUC Authorizations to the extent necessary to be
transferred as provided in this paragraph (b) no later than the date 90 days
after the respective acquisition date therefor.

                 SECTION 7.10.  Modifications to Certain Agreements.  The
Credit Parties will not consent to any modification, supplement or waiver of
any of the provisions of the Overhead Services Agreement (other than to add new
Restricted Companies as parties thereto) or the Tax Sharing Agreement (other
than to add new subsidiaries of NCI as parties thereto).  In addition, NCI will
not consent to any modification, supplement or waiver of any of the provisions
of the Public Note Indentures or the Public Notes without the prior consent of
the Required Parties).


                                  ARTICLE VIII

                               Events of Default

                 If any of the following events ("Events of Default") shall
occur:

                 (a)  the Borrower shall fail to pay any principal of any
         Tranche D Loan when and as the same shall become due and payable,
         whether at the due date thereof or at a date fixed for prepayment
         thereof or otherwise;





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<PAGE>   68
                                     - 63 -



                 (b)  the Borrower shall fail to pay any interest on any
         Tranche D Loan or any other amount (other than an amount referred to
         in clause (a) of this Article) payable under this Agreement, when and
         as the same shall become due and payable, and such failure shall
         continue unremedied for a period of three or more Business Days;

                 (c)  any representation or warranty made or deemed made by or
         on behalf of any Credit Party in or in connection with this Agreement
         or any of the other Basic Documents or any amendment or modification
         hereof or thereof (or in any report, certificate, financial statement
         or other document furnished pursuant to or in connection with this
         Agreement, any of the other Basic Documents or any amendment or
         modification hereof or thereof) shall prove to have been incorrect
         when made or deemed made in any material respect;

                 (d)  the Restricted Companies shall fail to observe or perform
         any covenant, condition or agreement contained in Section 6.02, 6.03
         (with respect to the existence of the Restricted Companies), 6.11 or
         6.12, Article VII, or in Section 5.01 or 6.02 of the Restricted
         Company Guarantee and Security Agreement;

                 (e)  any Credit Party shall fail to observe or perform any
         covenant, condition or agreement contained in this Agreement or any
         other Second Secured Loan Document (other than those specified in
         clause (c) or (d) of this Article), and such failure shall continue
         unremedied for a period of thirty or more days after notice thereof
         from any Vendor Lender to the Borrower;

                 (f)  any Credit Party shall fail to make any payment (whether
         of principal or interest and regardless of amount) in respect of any
         Material Indebtedness, when and as the same shall become due and
         payable;

                 (g)  any event or condition occurs that results in any
         Material Indebtedness becoming due prior to its scheduled maturity or
         that enables or permits (with or without the giving of notice, the
         lapse of time or both) the holder or holders of any Material
         Indebtedness or any trustee or agent on its or their behalf to cause
         any Material Indebtedness to become due, or to require the prepayment,
         repurchase, redemption or defeasance thereof, prior to its scheduled
         maturity; provided that this clause (g) shall not apply to secured
         Indebtedness that becomes due as a result of the voluntary sale or
         transfer of the property or assets securing such Indebtedness;

                 (h)  an involuntary proceeding shall be commenced or an
         involuntary petition shall be filed seeking (i) liquidation,
         reorganization or other relief in respect of any Credit Party or its
         debts, or of a substantial part of its assets, under any Federal,
         state or foreign bankruptcy, insolvency, receivership or similar law
         now or hereafter in effect or (ii) the appointment of a receiver,
         trustee, custodian, sequestrator,





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<PAGE>   69
                                     - 64 -



         conservator or similar official for any Credit Party or for a
         substantial part of its assets, and, in any such case, such proceeding
         or petition shall continue undismissed for 60 days or an order or
         decree approving or ordering any of the foregoing shall be entered;

                 (i)  any Credit Party shall (i) voluntarily commence any
         proceeding or file any petition seeking liquidation, reorganization or
         other relief under any Federal, state or foreign bankruptcy,
         insolvency, receivership or similar law now or hereafter in effect,
         (ii) consent to the institution of, or fail to contest in a timely and
         appropriate manner, any proceeding or petition described in clause (h)
         of this Article, (iii) apply for or consent to the appointment of a
         receiver, trustee, custodian, sequestrator, conservator or similar
         official for any Credit Party or for a substantial part of its assets,
         (iv) file an answer admitting the material allegations of a petition
         filed against it in any such proceeding, (v) make a general assignment
         for the benefit of creditors or (vi) take any action for the purpose
         of effecting any of the foregoing;

                 (j)  any Credit Party shall become unable, admit in writing or
         fail generally to pay its debts as they become due;

                 (k)  one or more judgments for the payment of money in an
         aggregate amount in excess of $10,000,000 shall be rendered against
         any one or more of the Credit Parties and the same shall remain
         undischarged for a period of 30 consecutive days during which
         execution shall not be effectively stayed, or any action shall be
         legally taken by a judgment creditor to attach or levy upon any assets
         of any Credit Party to enforce any such judgment;

                 (l)  an ERISA Event shall have occurred that, in the opinion
         of the Required Parties, when taken together with all other ERISA
         Events that have occurred, could reasonably be expected to result in a
         Material Adverse Effect;

                 (m)  a proceeding shall have been initiated by or before, or
         any action shall have been taken by, the FCC, a PUC, a court of
         competent jurisdiction, or other Governmental Authority which either:

                                  (i)  has resulted in the cancellation,
                 non-renewal or adverse modification of any one or more SMR
                 Licenses, radio channels authorized under SMR Licenses or PUC
                 Authorizations held by one or more of the Restricted
                 Companies, or

                                  (ii)  in the reasonable opinion of the
                 Required Parties, is likely to result in the cancellation,
                 non-renewal or adverse modification of any one or





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<PAGE>   70
                                     - 65 -



                 more SMR Licenses, radio channels authorized under SMR
                 Licenses, or PUC Authorizations held by one or more Restricted
                 Companies, 

         that, in the aggregate, in the judgment of the Required Parties, have
         resulted or are reasonably likely to result in a Material Adverse
         Effect, and the same shall continue uncured for a period of 45 or more
         days after notice thereof to the Borrower by the Required Parties;

                 (n)  any FCC License or PUC Authorization, or any other
         material operating assets, rights or other property, relating to the
         operation of all or any part of the Mobile Communications Business of
         any of the Restricted Companies shall be held by NCI or any of the
         Unrestricted Companies, other than any FCC Licenses or PUC
         Authorizations that are (i) acquired by Unrestricted Companies after
         September 27, 1996, (ii) not material to the Mobile Communications
         Business of the Restricted Companies, (iii) subject to management
         agreements in favor of the Restricted Companies and (iv) do not relate
         to a portion of the Mobile Communications Business of the Restricted
         Companies representing more than 5% of the aggregate Operating Cash
         Flow;

                 (o)  a reasonable basis shall exist for the assertion against
         any Credit Party, or any predecessor in interest of any Credit Party
         or their Affiliates, of (or there shall have been asserted against any
         Credit Party) any claims or liabilities, whether accrued, absolute or
         contingent, based on or arising from the generation, storage,
         transport, handling or disposal of Hazardous Materials or RF Emissions
         by any Credit Party or any of its subsidiaries, Affiliates or
         predecessors that, in the judgment of the Required Parties is
         reasonably likely to be determined adversely to any Credit Party, and
         the amount thereof (either individually or in the aggregate) is
         reasonably likely to have a Material Adverse Effect (insofar as such
         amount is payable by a Credit Party but after deducting any portion
         thereof that is reasonably expected to be paid by other creditworthy
         Persons jointly and severally liable therefor); or

                 (p)  Any of the following shall occur: (i) the Liens created
         by the Security Documents shall at any time, with respect to any
         material portion of the property of the Restricted Companies, not
         constitute valid and perfected Liens on the Collateral intended to be
         covered thereby (to the extent perfection by filing, registration,
         recordation or possession is required herein or therein) in favor of
         the Collateral Agent for the benefit of the Vendor Lenders hereunder,
         the Vendors under the Vendor Financing Agreement and the Lenders under
         the Credit Agreement, free and clear of all other Liens (other than
         Liens permitted under Section 7.02 or under the respective Security
         Documents); (ii) except for expiration in accordance with its terms,
         any of the Security Documents shall for whatever reason be terminated,
         or shall cease to be in full force and effect, with respect to any
         material portion of the





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<PAGE>   71
                                     - 66 -



         property of the Restricted Companies; or (iii) the enforceability of
         any of the Security Documents shall be contested by any Credit Party;

then, and in every such event (other than an event with respect to any Credit
Party described in clause (h) or (i) of this Article), and at any time
thereafter during the continuance of such event, the Required Vendor Lenders
may, by notice to the Borrower, take either or both of the following actions,
at the same or different times: (i) terminate the Tranche D Commitments, and
thereupon the Tranche D Commitments shall terminate immediately, and (ii)
declare the Tranche D Loans then outstanding to be due and payable in whole (or
in part, in which case any principal not so declared to be due and payable may
thereafter be declared to be due and payable), and thereupon the principal of
the Tranche D Loans so declared to be due and payable, together with accrued
interest thereon and other obligations of the Borrower accrued hereunder, shall
become due and payable immediately, without presentment, demand, protest or
other notice of any kind, all of which are hereby waived by the Borrower; and
in case of any event with respect to any Credit Party described in clause (h)
or (i) of this Article, the Tranche D Commitments shall automatically terminate
and the principal of the Tranche D Loans then outstanding, together with
accrued interest thereon and other obligations of the Borrower accrued
hereunder, shall automatically become due and payable, without presentment,
demand, protest or other notice of any kind, all of which are hereby waived by
the Borrower.


                                   ARTICLE IX

                            Intentionally Left Blank

                 This Article IX has been intentionally left blank.


                                   ARTICLE X

                                 Miscellaneous

                 SECTION 10.01.  Notices.  Except in the case of notices and
other communications expressly permitted to be given by telephone, all notices
and other communications provided for herein shall be in writing and shall be
delivered by hand or overnight courier service, mailed by certified or
registered mail or sent by telecopy, as follows:

                 (a)  if to NCI or the Borrower, to it at 1505 Farm Credit
         Drive, Suite 100, McLean, Virginia 22102, Attention Steven Shindler,
         Senior Vice President and Chief Financial Officer (Telecopy No.
         703-394-3011);





                   Second Secured Vendor Financing Agreement
<PAGE>   72
                                     - 67 -




                 (b)  if to any Restricted Company other than the Borrower, to
         such Restricted Company care of the Borrower at the address for
         notices indicated in clause (a) above;

                 (c)  if to Motorola, to it at 1301 East Algonquin Road,
         Schaumburg, Illinois 60196, Attention Vice President, Director of
         Financing (Telecopy No. 847-538-2491), with a copy to Gary Tatje at
         such address and to the General Counsel and Secretary at 1303 East
         Algonquin Road, Schaumburg, Illinois 60196; and

                 (d)  if to any Vendor Lender other than Motorola, at such
         address as shall be specified by such Vendor Lender at the time such
         Vendor Lender becomes a party hereto pursuant to an assignment
         permitted under Section 10.04.

Any party hereto may change its address or telecopy number for notices and
other communications hereunder by notice to the other parties hereto.  All
notices and other communications given to any party hereto in accordance with
the provisions of this Agreement shall be deemed to have been given on the date
of receipt.

                 SECTION 10.02.  Waivers; Amendments.

                 (a)  No failure or delay by any Vendor Lender in exercising
any right or power hereunder shall operate as a waiver thereof, nor shall any
single or partial exercise of any such right or power, or any abandonment or
discontinuance of steps to enforce such a right or power, preclude any other or
further exercise thereof or the exercise of any other right or power.  The
rights and remedies of the Vendor Lenders hereunder are cumulative and are not
exclusive of any rights or remedies that they would otherwise have.  No waiver
of any provision of this Agreement or consent to any departure by any
Restricted Company therefrom shall in any event be effective unless the same
shall be permitted by paragraph (b) of this Section 10.02, and then such waiver
or consent shall be effective only in the specific instance and for the purpose
for which given.  Without limiting the generality of the foregoing, the making
of a Tranche D Loan shall not be construed as a waiver of any Default,
regardless of whether any Vendor Lender may have had notice or knowledge of
such Default at the time.

                 (b)  Neither this Agreement nor any provision hereof may be
waived, amended or modified except pursuant to an agreement or agreements in
writing entered into by the Restricted Companies and the Required Vendor
Lenders; provided that no such agreement shall:

                          (i)  increase the Tranche D Commitment of any Vendor
         Lender without the written consent of such Vendor Lender;





                   Second Secured Vendor Financing Agreement
<PAGE>   73
                                     - 68 -



                          (ii)  reduce the principal amount of any Tranche D
         Loan or reduce the rate of interest thereon without the written
         consent of the Vendor Lender affected thereby;

                          (iii)  postpone the scheduled date of payment of the
         principal amount of any Tranche D Loan, or any interest thereon, or
         reduce the amount of, waive or excuse any such payment, or postpone
         the scheduled date of expiration of any Tranche D Commitment, without
         the written consent of the Vendor Lender affected thereby;

                          (iv)  change Section 2.16(c) or (d) in a manner that
         would alter the pro rata sharing of payments required thereby, without
         in each case the written consent of each Vendor Lender;

                          (v)  alter the rights or obligations of the Borrower
         to prepay Tranche D Loans without the written consent of  each Vendor
         Lender (other than the obligations of the Borrower under Section
         2.09(b)(iii), which may be altered with the consent of the Required
         Vendor Lenders);

                          (vi)  change any of the provisions of this Section
         10.02 or the definition of "Required Parties", "Required Vendor
         Lenders", or any other provision hereof specifying the number or
         percentage of Vendor Lenders hereunder required to waive, amend or
         modify any rights hereunder or any other Second Secured Loan Document
         or make any determination or grant any consent hereunder or
         thereunder, without the written consent of each Vendor Lender; or

                          (vii)  release NCI from its obligations in respect of
         its Guarantee under Article III without the written consent of each
         Vendor Lender.

                 (c)  Neither any Security Document nor any provision thereof
may be waived, amended or modified except pursuant to an agreement or
agreements in writing entered into by the Restricted Companies party thereto,
and by the Collateral Agent with the consent of the Required Vendor Lenders,
and the appropriate Lenders and Vendors, as more particularly provided in
Section 5.02(c) of the Second Secured Intercreditor and Collateral Agency
Agreement.

                 SECTION 10.03.  Expenses; Indemnity; Damage Waiver.

                 (a)  The Credit Parties jointly and severally agree to pay, or
reimburse the Vendor Lenders for paying, (i) all amounts that the Collateral
Agent is required to make under any indemnity issued to any bank with which
lock box or segregated deposit arrangements are entered into pursuant to
Section 5.01((i) or the Restricted Company





                   Second Secured Vendor Financing Agreement
<PAGE>   74
                                     - 69 -



Guarantee and Security Agreement, (ii) all out-of-pocket expenses incurred by a
Vendor Lender, including the fees, charges and disbursements of any counsel for
such Vendor Lender, in connection with the enforcement or protection of its
rights in connection with this Agreement and the other Second Secured Loan
Documents, including its rights under this Section 10.03, or in connection with
the Tranche D Loans made hereunder, including in connection with any workout,
restructuring or negotiations in respect thereof, (iii) all transfer, stamp,
documentary or other similar taxes, assessments or charges levied by any
governmental or revenue authority in respect of this Agreement or any of the
other Second Secured Loan Documents or any other document referred to herein or
therein and all costs, expenses, taxes, assessments and other charges incurred
in connection with any filing, registration, recording or perfection of any
security interest contemplated by any Security Document or any other document
referred to therein, and (iv) all costs, expenses and other charges in respect
of title insurance procured with respect to the Liens created pursuant to the
Mortgages.

                 (b)  The Credit Parties jointly and severally agree to
indemnify each Vendor Lender, and each Related Party of a Vendor Lender (each
such Person being called an "Indemnitee") against, and hold each Indemnitee
harmless from, any and all losses, claims, damages, liabilities and related
expenses, including the fees, charges and disbursements of any counsel for any
Indemnitee, incurred by or asserted against any Indemnitee arising out of, in
connection with, or as a result of (i) the execution or delivery of this
Agreement, the other Second Secured Loan Documents or any agreement or
instrument contemplated hereby, the performance by the parties hereto and
thereto of their respective obligations hereunder or thereunder or the
consummation of the Transactions or any other transactions contemplated hereby
or thereby, (ii) any Tranche D Loan or the use of the proceeds therefrom, (iii)
any actual or alleged presence or release of Hazardous Materials or RF
Emissions on or from any property owned or operated by any Credit Party or any
of their subsidiaries, or any Environmental Liability related in any way to any
Credit Party or any of their subsidiaries, or (iv) any actual or prospective
claim, litigation, investigation or proceeding relating to any of the
foregoing, whether based on contract, tort or any other theory and regardless
of whether any Indemnitee is a party thereto; provided that such indemnity
shall not, as to any Indemnitee, be available to the extent that such losses,
claims, damages, liabilities or related expenses (are determined by a court of
competent jurisdiction by final and nonappealable judgment to have) resulted
from the gross negligence or wilful misconduct of such Indemnitee.

                 (c)  This paragraph (c) has been intentionally left blank.

                 (d)  To the extent permitted by applicable law, none of the
Credit Parties shall assert, and each Credit Party hereby waives, any claim
against any Indemnitee, on any theory of liability, for special, indirect,
consequential or punitive damages (as opposed to direct or actual damages)
arising out of, in connection with, or as a result of, this





                   Second Secured Vendor Financing Agreement
<PAGE>   75
                                     - 70 -



Agreement, the other Second Secured Loan Documents or any agreement or
instrument contemplated hereby or thereby, the Transactions or any Tranche D
Loan or the use of the proceeds thereof.

                 (e)  All amounts due under this Section 10.03 shall be payable
promptly after written demand therefor.

                 SECTION 10.04.  Successors and Assigns.

                 (a)  The provisions of this Agreement shall be binding upon
and inure to the benefit of the parties hereto and their respective successors
and assigns permitted hereby, except that no Credit Party may assign or
otherwise transfer any of its rights or obligations hereunder without the prior
written consent of each Vendor Lender (and any attempted assignment or transfer
by any Credit Party without such consent shall be null and void).  Nothing in
this Agreement, expressed or implied, shall be construed to confer upon any
Person (other than the parties hereto, their respective successors and assigns
permitted hereby and, to the extent expressly contemplated hereby, the Related
Parties of each Vendor Lender) any legal or equitable right, remedy or claim
under or by reason of this Agreement.

                 (b)  Any Vendor Lender may assign its rights and obligations
under this Agreement (including all or a portion of its Tranche D Commitment,
and the Tranche D Loans at the time owing to it); provided that

                          (i)  the Borrower must give its prior written consent
         to such assignment (which consent shall not be unreasonably withheld
         or delayed), and

                          (ii)  except in the case of an assignment of the
         entire remaining amount of the assigning Vendor Lender's Tranche D
         Commitment or Tranche D Loans, the amount of the Tranche D Commitment
         or Tranche D Loans of the assigning Vendor Lender subject to each such
         assignment shall not be less than $5,000,000 unless the Borrower shall
         otherwise consent,

provided further that no consent of the Borrower shall be required if an Event
of Default under clause (h) or (i) of Article VIII has occurred and is
continuing, or if such assignment is by one Vendor Lender to another Vendor
Lender, or to a Vendor or Lender.

                 From and after the effective date of any such assignment, the
assignee thereunder shall be a party hereto and have (to the extent of such
assignment) the rights and obligations of the respective assigning Vendor
Lender under this Agreement, and (to the extent of such assignment) the
assigning Vendor Lender thereunder shall be released from its obligations under
this Agreement (and shall, to such extent, cease to be a party hereto but shall
continue to be entitled to the benefits of Sections 2.15 and 10.03).  Upon any
such





                   Second Secured Vendor Financing Agreement
<PAGE>   76
                                     - 71 -



assignment, the respective assignee shall be deemed to have become a party to
the Second Secured Intercreditor and Collateral Agency Agreement (and thereby
to have consented to be bound by, and subject to the provisions of, the Second
Secured Intercreditor and Collateral Agency Agreement).  Any assignment or
transfer by a Vendor Lender of rights or obligations under this Agreement that
does not comply with this paragraph shall be treated for purposes of this
Agreement as a sale by such Vendor Lender of a participation in such rights and
obligations in accordance with paragraph (e) of this Section 10.04.

                 (c)  This paragraph (c) has been intentionally left blank.

                 (d)  This paragraph (d) has been intentionally left blank.

                 (e)  Any Vendor Lender may, without the consent of the
Restricted Companies, sell participations to one or more banks or other
entities (a "Participant") in all or a portion of such Vendor Lender's rights
and obligations under this Agreement (including all or a portion of its Tranche
D Commitment, and the Tranche D Loans owing to it); provided that (i) such
Vendor Lender's obligations under this Agreement shall remain unchanged, (ii)
such Vendor Lenders shall remain solely responsible to the other parties hereto
for the performance of such obligations and (iii) the Borrower and the other
Vender Lenders shall continue to deal solely and directly with such Vendor
Lender in connection with such Vender Lender's rights and obligations under
this Agreement.  Any agreement or instrument pursuant to which a Vendor Lender
sells such a participation shall provide that such Vendor Lender shall retain
the sole right to enforce this Agreement and to approve any amendment,
modification or waiver of any provision of this Agreement; provided that such
agreement or instrument may provide that such Vendor Lender will not, without
the consent of the Participant, agree to any amendment, modification or waiver
described in the first proviso to Section 10.02(b) that affects such
Participant.  Subject to paragraph (f) of this Section 10.04, the Borrower
agrees that each Participant shall be entitled to the benefits of Section 2.15
to the same extent as if it were a Vendor Lender and had acquired its interest
by assignment pursuant to paragraph (b) of this Section 10.04.

                 (f)  A Participant shall not be entitled to receive any
greater payment under Section 2.15 than the applicable Vendor Lender would have
been entitled to receive with respect to the participation sold to such
Participant, unless the sale of the participation to such Participant is made
with the Borrower's prior written consent.

                 (g)  Any Vendor Lender may at any time pledge or assign a
security interest in all or any portion of its rights under this Agreement to
secure obligations of such Vendor Lender, including any such pledge or
assignment to a Federal Reserve Bank, and this Section 10.04 shall not apply to
any such pledge or assignment of a security interest; provided that no such
pledge or assignment of a security interest shall release a Vendor Lender from
any





                   Second Secured Vendor Financing Agreement
<PAGE>   77
                                     - 72 -



of its obligations hereunder or substitute any such assignee for such Vendor
Lender as a party hereto or as a party to any of the Second Secured Loan
Documents.

                 (h)  Anything in this Section 10.04 to the contrary
notwithstanding, (i) no Vendor Lender may assign or participate any interest in
any Tranche D Loan held by it hereunder to the Borrower or any of its
Affiliates or subsidiaries without the prior consent of each Vendor Lender and
(ii) without the prior consent of the Borrower, Motorola shall (except as a
result of any assignment or participation made on the basis of full recourse to
Motorola) at all times either (x) hold Tranche D Loans hereunder, or "Loans"
under the Vendor Financing Agreement, in an aggregate principal amount at least
equal to $50,000,000 (or such lesser amount as shall represent the amount to
which such $50,000,000 would be reduced ratably in accordance with the
repayment schedule set forth in Section 2.08(b) of the Vendor Financing
Agreement) or (y) be obligated in respect of the "Tranche A Commitment" under
the Vendor Financing Agreement in an aggregate amount at least equal to
$50,000,000 (or such lesser amount as shall represent the amount to which such
$50,000,000 would be reduced ratably in accordance with the repayment schedule
set forth in Section 2.08(b) of the Vendor Financing Agreement), and for
purposes of this paragraph (h), Motorola shall be deemed not to hold Tranche D
Loans hereunder, or "Loans" or "Tranche A Commitment" under the Vendor
Financing Agreement, if it has either assigned or sold participations in an
interest in the Tranche D Loans, or such "Loans" or "Tranche A Commitment", as
otherwise permitted under this Section 10.04.

                 (i)  NCI agrees with Motorola to use its best efforts in
assisting Motorola to sell to third parties, on a non-recourse basis, a
sufficient portion of the exposure to NCI and its Subsidiaries held by Motorola
for its own account (or guaranteed by Motorola) so that the total outstandings
so held (or guaranteed) by Motorola hereunder and under the Vendor Financing
Agreement, and in respect of any "Tranche E Loans" as contemplated by the Term
Sheet dated March 26, 1997 between NCI and Motorola, shall not be greater than
$555,000,000 at any one time.

                 SECTION 10.05.  Survival.  All covenants, agreements,
representations and warranties made by the Credit Parties herein and in the
other Second Secured Loan Documents, and in the certificates or other
instruments delivered in connection with or pursuant to this Agreement and the
other Second Secured Loan Documents, shall be considered to have been relied
upon by the other parties hereto and shall survive the execution and delivery
of this Agreement and the other Second Secured Loan Documents and the making of
any Tranche D Loans, regardless of any investigation made by any such other
party or on its behalf and notwithstanding that any Vendor Lender may have had
notice or knowledge of any Default or incorrect representation or warranty at
the time any credit is extended hereunder, and shall continue in full force and
effect so long as the principal of or any accrued interest on any Tranche D
Loan or any other amount payable under this Agreement or the other Second
Secured Loan Documents is outstanding and so long as the





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<PAGE>   78
                                     - 73 -



Tranche D Commitments have not expired or terminated.  The provisions of
Sections 2.15 and 10.03 shall survive and remain in full force and effect
regardless of the consummation of the transactions contemplated hereby, the
repayment of the Tranche D Loans, the expiration or termination of the Tranche
D Commitments or the termination of this Agreement or any other Second Secured
Loan Document or any provision hereof or thereof.

                 SECTION 10.06.  Counterparts.  This Agreement may be executed
in counterparts (and by different parties hereto on different counterparts),
each of which shall constitute an original, but all of which when taken
together shall constitute a single contract.  This Agreement constitutes the
entire contract among the parties relating to the subject matter hereof and
supersedes any and all previous agreements and understandings, oral or written,
relating to the subject matter hereof.

                 SECTION 10.07.  Severability.  Any provision of this Agreement
held to be invalid, illegal or unenforceable in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such invalidity, illegality
or unenforceability without affecting the validity, legality and enforceability
of the remaining provisions hereof; and the invalidity of a particular
provision in a particular jurisdiction shall not invalidate such provision in
any other jurisdiction.

                 SECTION 10.08.  Right of Setoff.  If an Event of Default shall
have occurred and be continuing, each Vendor Lender is hereby authorized at any
time and from time to time, to the fullest extent permitted by law, to set off
and apply any and all indebtedness at any time owing by such Vendor Lender to
or for the credit or the account of the Borrower against any of and all the
obligations of the Borrower now or hereafter existing under this Agreement held
by such Vendor Lender, irrespective of whether or not such Vendor Lender shall
have made any demand under this Agreement and although such obligations may be
unmatured.  The rights of each Vendor Lender under this Section 10.08 are in
addition to any other rights and remedies (including other rights of setoff)
which such Vendor Lender may have.

                 SECTION 10.09.  Governing Law; Jurisdiction; Consent to
Service of Process.

                 (a)  This Agreement shall be construed in accordance with and
governed by the law of the State of New York.

                 (b)  Each party hereto hereby irrevocably and unconditionally
submits, for itself and its property, to the nonexclusive jurisdiction of the
Supreme Court of the State of New York sitting in New York County and of the
United States District Court of the Southern District of New York, and any
appellate court from any thereof, in any action or proceeding arising out of or
relating to this Agreement or the other Second Secured Loan





                   Second Secured Vendor Financing Agreement
<PAGE>   79
                                     - 74 -



Documents, or for recognition or enforcement of any judgment, and each of the
parties hereto hereby irrevocably and unconditionally agrees that all claims in
respect of any such action or proceeding may be heard and determined in such
New York State court (or, to the extent permitted by law, in such Federal
court).  Each of the parties hereto agrees that a final judgment in any such
action or proceeding shall be conclusive and may be enforced in other
jurisdictions by suit on the judgment or in any other manner provided by law.
Nothing in this Agreement shall affect any right that any Vendor Lender may
otherwise have to bring any action or proceeding relating to this Agreement
against any Credit Party or its properties in the courts of any jurisdiction.

                 (c)  Each party hereto hereby irrevocably and unconditionally
waives, to the fullest extent it may legally and effectively do so, any
objection which it may now or hereafter have to the laying of venue of any
suit, action or proceeding arising out of or relating to this Agreement or the
other Second Secured Loan Documents in any court referred to in paragraph (b)
of this Section 10.09.  Each of the parties hereto hereby irrevocably waives,
to the fullest extent permitted by law, the defense of an inconvenient forum to
the maintenance of such action or proceeding in any such court.

                 (d)  Each party to this Agreement irrevocably consents to
service of process in the manner provided for notices in Section 10.01.
Nothing in this Agreement will affect the right of any party to this Agreement
to serve process in any other manner permitted by law.

                 SECTION 10.10.  WAIVER OF JURY TRIAL.  EACH PARTY HERETO
HEREBY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY RIGHT IT
MAY HAVE TO A TRIAL BY JURY IN ANY LEGAL PROCEEDING DIRECTLY OR INDIRECTLY
ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED
HEREBY (WHETHER BASED ON CONTRACT, TORT OR ANY OTHER THEORY).  EACH PARTY
HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER
PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT,
IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER AND (B)
ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER
INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION 10.10.

                 SECTION 10.11.  Headings.  Article and Section headings and
the Table of Contents used herein are for convenience of reference only, are
not part of this Agreement and shall not affect the construction of, or be
taken into consideration in interpreting, this Agreement.





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<PAGE>   80
                                     - 75 -



                 SECTION 10.12.  Confidentiality.  Each of the Vendor Lenders
hereby agrees to maintain the confidentiality of the Information (as defined
below), except that Information may be disclosed (a) to its and its Affiliates,
directors, officers, employees and agents, including accountants, legal counsel
and other advisors (it being understood that the Persons to whom such
disclosure is made will be informed of the confidential nature of such
Information and instructed to keep such Information confidential), (b) to the
extent requested by any regulatory authority, (c) to the extent required by
applicable laws or regulations or by any subpoena or similar legal process, (d)
to any other party to this Agreement, (e) in connection with the exercise of
any remedies hereunder or any suit, action or proceeding relating to this
Agreement or the enforcement of rights hereunder, (f) subject to the execution
and delivery of an agreement containing provisions substantially the same as
those of this Section 10.12, to any assignee of or Participant in, or any
prospective assignee of or Participant in, any of its rights or obligations
under this Agreement, (g) with the consent of the Borrower or (h) to the extent
such Information (i) becomes publicly available other than as a result of a
breach of this Section 10.12 or (ii) becomes available to a Vendor Lender on a
nonconfidential basis from a source other than the Borrower.

                 For the purposes of this Section 10.12, "Information" means
all information received from the Borrower relating to the Credit Parties or
their business, other than any such information that is available to any Vendor
Lender on a nonconfidential basis prior to disclosure by the Borrower; provided
that, in the case of information received from the Borrower after the date
hereof, such information is clearly identified at the time of delivery as
confidential.  Any Person required to maintain the confidentiality of
Information as provided in this Section 10.12 shall be considered to have
complied with its obligation to do so if such Person has exercised the same
degree of care to maintain the confidentiality of such Information as such
Person would accord to its own confidential information.

                 SECTION 10.13.  Intentionally Left Blank.  This Section 10.13
has been intentionally left blank.

                 SECTION 10.14.  Obligations Senior.  The obligations of the
Restricted Companies hereunder and under the other Second Secured Loan
Documents constitute "senior Debt" for the purposes of the second paragraph of
Section 10.12 of the January 1994 Indenture.





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<PAGE>   81
                                     - 76 -



                 IN WITNESS WHEREOF, the parties hereto have caused this Second
Secured Vendor Financing Agreement to be duly executed by their respective
authorized officers as of the day and year first above written.


                            NEXTEL COMMUNICATIONS, INC.
                         
                               By   THOMAS J. SIDMAN
                                    -------------------------------
                                    Name: Thomas J. Sidman
                                    Title: Vice President
                         
                         RESTRICTED COMPANIES
                         
                            NEXTEL FINANCE COMPANY (successor to        
                              Fleet Call Corporation),                  
                                                                        
                               By    THOMAS J. SIDMAN
                                     -------------------------------    
                                     Name: Thomas J. Sidman
                                     Title: Vice President
                                                                        
                            ADVANCED MOBILECOMM OF                      
                              NORTH CAROLINA, INC.                      
                            AIRLINK COMMUNICATIONS, INC.                
                              (successor to TRS, Inc.)                  
                            AMERICAN MOBILE SYSTEMS,                    
                              INCORPORATED (successor to Saber          
                              Communications, Inc.)                     
                            DIAL CALL, INC.                             
                            DIAL DISTANCE, INC.                         
                            FC NEW YORK, INC. (successor to Metrocom    
                              Trunked Radio Communication Systems, Inc.)
                            FCI 900, INC.                               
                            FLEET CALL OF TEXAS, INC. (successor to     
                              FM Tower Company, Metrolink               
                              Communications Corporation and National   
                              Tower Trunking Systems, Inc.)             





                   Second Secured Vendor Financing Agreement
<PAGE>   82
                                     - 77 -



                         NEXTEL COMMUNICATIONS OF THE  
                           MID-ATLANTIC, INC. (successor to Dispatch  
                           Communications of Maryland, Inc., Dispatch 
                           Communications of Minnesota, Inc., Dispatch
                           Communications of New England, Inc.,       
                           Dispatch Communications of Pennsylvania,Inc.)
                         NEXTEL LICENSE HOLDINGS 1, INC.                
                         NEXTEL LICENSE HOLDINGS 2, INC.                
                           (successor to Comqor, Inc.)                  
                         NEXTEL LICENSE HOLDINGS 3, INC.                
                           (successor to Dial Call Arkansas, Inc.,      
                           Custom Radio/Johnson Communications, Inc.,   
                           Dial Call Florida, Inc., Dial Call           
                           Kentucky, Inc., Dial Call Louisiana, Inc.,   
                           Dial Call Texas, Inc., Dial Call             
                           Virginia, Inc., Dial Call West Virginia, Inc.
                           and U.S. Digital, Inc.)                      
                         NEXTEL LICENSE HOLDINGS 4, INC.                
                         NEXTEL OF TEXAS, INC. (successor to Fort       
                           Worth Communications, Inc.)                  
                         NEXTEL WEST CORP.                              
                           (successor to Airwave Communications Corp.   
                           (Seattle), C-Call Corporation, Dispatch      
                           Communications of Arizona, Inc., ESMR Sub,   
                           Inc., Fleet Call of Utah, Inc., Fleet Call   
                           West, Inc., Mijac Enterprises, Inc., Mobile  
                           Radio of Illinois, Inc., Motorola SF, Inc.,  
                           Nextel Hawaii Acquisition Corp.,             
                           Nextel Utah Acquisition Corp., Nextel        
                           Western Acquisition Corp., OneComm Corporation, 
                              N.A., Powerfone  
                           Holdings, Inc., Powerfone, Inc.,  
                           Smart SMR of Illinois, Inc., Shoreland
                           Communications, Inc. and Spectrum Resources 
                           of the Midwest, Inc.)                       
                         SAFETY NET, INC.                              
                         SMART SMR, INC.                               





                   Second Secured Vendor Financing Agreement
<PAGE>   83
                                     - 78 -



                         SMART SMR OF CALIFORNIA, INC.
                         SMART SMR OF NEW YORK, INC.
                            
                              By    THOMAS J. SIDMAN
                                    -------------------------------
                                    Name: Thomas J. Sidman
                                    Title: Vice President
                            
                            FORT WORTH TRUNKED RADIO
                              LIMITED PARTNERSHIP
                            
                            By Nextel of Texas,Inc.,
                                 a General Partner
                            
                            
                               By   THOMAS J. SIDMAN
                                    -------------------------------
                                    Name: Thomas J. Sidman
                                    Title: Vice President
                         
                         
            VENDOR LENDERS
               
               MOTOROLA, INC.
               
                  by    GARY B. TATJE
                        -----------------------------
                        Name: Gary B. Tatje
                        Title: Director, Customer Financing





                   Second Secured Vendor Financing Agreement

<PAGE>   1


                                                               EXHIBIT 99.4

[LOGO]                                           Nextel Communications, Inc.
                                                 1505 Farm Credit Drive
 For Immediate Release                           McLean, VA 22102
                                                 703 394-3000


                                                                    Contacts:
                                                          Investor Relations:
                                                  Paul Blalock (703) 394-3500
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          Nextel Appoints Frank Drendel To Board Of Directors

     McLean, Va., August 25, 1997 -- Nextel Communications, Inc. (NASDAQ:
NXTL), today announced the appointment of Frank M. Drendel to its board of
directors.  Mr. Drendel is chairman and chief executive officer of CommScope,
Inc., based in Hickory, North Carolina, a publicly traded company that is the
world's largest manufacturer of coaxial cable and a leading supplier of
high-performance electronic cables for LAN and other applications.  Mr.
Drendel's appointment was approved August 20 at a board of directors' meeting.

     Mr. Drendel also serves on the board of NextLevel Systems, Inc., a world
leader in broadband transmission, distribution and access control technologies
for cable, satellite and terrestrial broadcasting applications, and is a
member of the National Cable Television Association (NCTA) presently serving
on its board of directors.  He has been a recipient of many NCTA awards
including the Challenger Award, Associates Award, and the President's Award.
Mr. Drendel also is a member of the C-SPAN board of directors.

     "Frank's knowledge of and experience in the telecommunications industry
will be of significant value to our board," said Daniel F. Akerson, chairman
and chief executive officer of Nextel.  "We welcome him and look forward to
his contributions as we continue to expand our company."

     Mr. Drendel is a graduate of Northern Illinois University with a B.S.
degree in marketing.  He has been involved in the U.S. CATV and
telecommunications industries his entire career.  He has been CEO of CommScope
since 1976, and was vice chairman of M/A-COM, Inc. during the period
CommScope, Inc. was part of M/A-COM's Cable/Home Communications Group
(1980-1986).

     Nextel Communications, Inc., based in McLean, Virginia, is the nation's
largest provider of all-digital wireless services.  Nextel now offers enhanced
digital wireless service in more than 275 cities making it the largest
guaranteed all-digital network providing commercial service in the U.S. today.
To learn more about Nextel and its services, visit Nextel's website at
http://www.nextel.com.

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