<PAGE>

                                                                   EXHIBIT 10.31

                                                                  Execution Copy
================================================================================




                       PREFERRED STOCK PURCHASE AGREEMENT

                                  by and among

                          ADVANCED RADIO TELECOM CORP.

                                      and

                   THE PURCHASERS LISTED ON SCHEDULE I HERETO



                            Dated as of June 1, 1999




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<PAGE>

                               TABLE OF CONTENTS
<TABLE>
<S>                                                                                                  <C>
ARTICLE I

   THE PURCHASE...................................................................................    1
     Section 1.1.   Definitions....................................................................   1
     Section 1.2.   Sale and Purchase of Preferred Stock...........................................   1
     Section 1.3.   Bridge Loan and Warrants.......................................................   2
     Section 1.4.   The Closing....................................................................   3

ARTICLE II

   REPRESENTATIONS AND WARRANTIES OF THE COMPANY..................................................    3
     Section 2.1.   Organization and Qualification; Subsidiaries...................................   3
     Section 2.2.   Certificate of Incorporation and By-Laws.......................................   4
     Section 2.3.   Capitalization.................................................................   4
     Section 2.4.   Authority Relative to this Agreement and DGCL Section 203......................   6
     Section 2.5.   No Conflict; Required Filings and Consents.....................................   7
     Section 2.6.   Compliance.....................................................................   8
     Section 2.7.   SEC Filings; Financial Statements..............................................   9
     Section 2.8.   Absence of Certain Changes or Events...........................................  10
     Section 2.9.   No Undisclosed Liabilities.....................................................  10
     Section 2.10.  Absence of Litigation.........................................................   11
     Section 2.11.  Employee Benefit Plans........................................................   11
     Section 2.12.  Proxy Statement...............................................................   12
     Section 2.13.  Title to Property.............................................................   12
     Section 2.14.  Restrictions on Business Activities...........................................   12
     Section 2.15.  Taxes.........................................................................   13
     Section 2.16.  Environmental Matters.........................................................   13
     Section 2.17.  Intellectual Property.........................................................   14
     Section 2.18.  Certain Agreements of Officers and Employees..................................   15
     Section 2.19.  Regulatory Matters............................................................   15
     Section 2.20.  Rank of Notes.................................................................   16
     Section 2.21.  Interested Party Transactions.................................................   16
     Section 2.22.  Insurance.....................................................................   16
     Section 2.23.  Brokers.......................................................................   17
     Section 2.24.  Disclosure....................................................................   17
     Section 2.25.  Securities Laws...............................................................   17
     Section 2.26.  Acquiring Person..............................................................   17
     Section 2.27.  Acceleration..................................................................   17
     Section 2.28.  Board of Directors............................................................   18
</TABLE>

                                      -i-
<PAGE>

<TABLE>
<S>                                                                                                  <C>
ARTICLE III

   REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS...............................................   18
     Section 3.1.  Organization...................................................................   18
     Section 3.2.  Due Authorization..............................................................   18
     Section 3.3.  Acquisition for Investment.....................................................   18
     Section 3.4.  Brokers or Finders.............................................................   18
     Section 3.5.  Accredited Investor............................................................   19
     Section 3.6.  Financial Condition............................................................   19
     Section 3.7.  Experience.....................................................................   19
     Section 3.8.  Non-U.S. Ownership.............................................................   19
     Section 3.9.  Beneficial Ownership...........................................................   19
     Section 3.10. Affiliates....................................................................    19
     Section 3.11. Proxy Statement...............................................................    19

ARTICLE IV

   ADDITIONAL AGREEMENTS..........................................................................   20
     Section 4.1.  HSR Act........................................................................   20
     Section 4.2.  Proxy Statement................................................................   20
     Section 4.3.  Stockholders Meeting...........................................................   20
     Section 4.4.  Alternative Transactions.......................................................   20
     Section 4.5.  Access to Information..........................................................   22
     Section 4.6.  Confidentiality................................................................   22
     Section 4.7.  Consents; Approvals............................................................   23
     Section 4.8.  Public Announcements...........................................................   24
     Section 4.9.  Listing........................................................................   24
     Section 4.10. Board of Directors.............................................................   24
     Section 4.11. Certificate of Designation.....................................................   26
     Section 4.12. Increase of Option Pool........................................................   26
     Section 4.13. Use of Proceeds................................................................   27
     Section 4.14. Interim Operations.............................................................   27
     Section 4.15. Restricted Securities..........................................................   28
     Section 4.16. Preemptive Rights..............................................................   28
     Section 4.17. Amendment of Rights Agreement..................................................   31

ARTICLE V

   CONDITIONS TO THE STOCK PURCHASE...............................................................   31
     Section 5.1.  Conditions to Obligation of Each Party to Effect the Stock Purchase............   31
     Section 5.2.  Additional Conditions to Obligations of the Purchasers.........................   31
     Section 5.3.  Additional Conditions to Obligation of the Company.............................   33
</TABLE>

                                     -ii-
<PAGE>

<TABLE>
<S>                                                                                                  <C>
ARTICLE VI

   TERMINATION....................................................................................   34
     Section 6.1.  Termination....................................................................   34
     Section 6.2.  Effect of Termination..........................................................   36
     Section 6.3.  Fees and Expenses..............................................................   36

ARTICLE VII

   GENERAL PROVISIONS.............................................................................   37
     Section 7.1.  Effectiveness of Representations, Warranties and Agreements; Knowledge, Etc....   37
     Section 7.2.  Restrictive Legends............................................................   37
     Section 7.3.  Notices........................................................................   38
     Section 7.4.  Certain Definitions............................................................   39
     Section 7.5.  Notification...................................................................   41
     Section 7.6.  Amendment......................................................................   41
     Section 7.7.  Waiver.........................................................................   41
     Section 7.8.  Cooperation....................................................................   41
     Section 7.9.  Headings.......................................................................   41
     Section 7.10. Severability...................................................................   41
     Section 7.11. Entire Agreement...............................................................   42
     Section 7.12. Assignment.....................................................................   42
     Section 7.13. Parties in Interest............................................................   42
     Section 7.14. Failure or Indulgence Not Waiver; Remedies Cumulative..........................   42
     Section 7.15. Governing Law..................................................................   42
     Section 7.16. Counterparts...................................................................   42
</TABLE>

Schedules and Exhibits
----------------------
     Schedule I     List of Purchasers
     Schedule II    Wire Transfer Instructions
     Schedule III   Schedule of Beneficial Ownership
     Schedule IV    Terms of Lucent Amendments
     Exhibit A      Form of Bridge Note
     Exhibit B      Form of Warrant
     Exhibit C      Certificate of Designation
     Exhibit D      Form of Opinion of Ropes & Gray
     Exhibit E      Form of Opinion of FCC Counsel
     Exhibit F      Registration Rights Agreement
     Exhibit G      Qwest Private Line Agreement
     Exhibit H      Co-Location License Agreement
     Exhibit I      Coordinated Marketing Agreement
     Exhibit J      Form of Standstill Agreement

     Company's Disclosure Schedule

                                     -iii-
<PAGE>

                       PREFERRED STOCK PURCHASE AGREEMENT

     This Preferred Stock Purchase Agreement is dated as of June 1, 1999 (this
"AGREEMENT"), among Advanced Radio Telecom Corp., a Delaware corporation (the
"COMPANY"), and the purchasers listed on Schedule I hereto (the "PURCHASERS").

                                  WITNESSETH:

     WHEREAS, the Purchasers wish to purchase from the Company, and the Company
wishes to sell and issue to the Purchasers (the "STOCK PURCHASE"), an aggregate
of 2,635,908 shares of the Company's Series A Convertible Preferred Stock,
$0.001 par value per share (the "SERIES A PREFERRED STOCK") and 501,592 shares
of the Company's Series B Non-Voting Convertible Preferred Stock, $0.001 par
value per share (the "SERIES B PREFERRED STOCK", and together with the Series A
Preferred Stock and the Series C Non-Voting Convertible Preferred Stock, $0.001
par value per share (the "SERIES C PREFERRED STOCK"), the "PREFERRED STOCK");
and

     WHEREAS, contemporaneously with the execution of this Agreement, the
Purchasers and the Company are executing and delivering the Standstill Agreement
(hereinafter defined) and the Company is executing and delivering the Warrants
(hereinafter defined) and the Notes (hereinafter defined) and the Purchasers are
advancing the Company $45,019,920; and

     WHEREAS, the Purchasers and the Company are entering into this Agreement to
provide for the purchase and sale of the Preferred Stock and to establish
various rights and obligations in connection therewith.

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
herein set forth, the parties agree as follows:

                                   ARTICLE I

                                  THE PURCHASE

     Section 1.1.  Definitions.  Certain terms are used in this Agreement as
specifically defined herein.  These definitions are set forth herein or referred
to in Section 7.4 hereof.

     Section 1.2.  Sale and Purchase of Preferred Stock.

          Section 1.2.1.  Purchase.  Subject to the terms and conditions of this
Agreement, and in reliance on the representations and warranties set forth in
this Agreement, the Company hereby agrees to sell to each of the Purchasers, and
each of the Purchasers
<PAGE>

hereby agrees severally to purchase from the Company, at the Closing (as
hereinafter defined) and at a purchase price of $80.00 per share (the "PURCHASE
PRICE"), the number of shares of Series A Preferred Stock and the number of
shares of Series B Preferred Stock as are set forth on Schedule I as being
purchased by such Purchaser (such shares of Series A Preferred Stock and Series
B Preferred Stock purchased hereunder, the "SHARES"). The aggregate Purchase
Price of the Shares purchased and sold hereunder is $251,000,000 (the
"INVESTMENT"). The terms of the Series A Preferred Stock, the Series B Preferred
Stock and the Series C Preferred Stock shall be those set forth in the
Certificate of Designation (as hereinafter defined).

          Section 1.2.2.  Alternative Commitment.  In the event that MeriTech
Capital Partners ("MeriTech") has not made the advance provided in Section 1.3
prior to June 15, 1999, Oak Investment Partners ("Oak"), Worldview Technology
("Worldview"), Accel Partners ("Accel") and Brentwood Venture Capital
("Brentwood") severally agree to purchase from the Company at the Closing at a
purchase price of $80.00 per share the additional number of shares of Series A
Preferred Stock and the additional number of shares of Series B Preferred Stock
as are set forth on Schedule I, and MeriTech on June 15, 1999 shall cease to be
a party to this Agreement for all purposes.

     Section 1.3.  Bridge Loan and Warrants.  The Purchasers severally agree to
advance to the Company an aggregate of $50,000,000 (the "LOAN") on the terms set
forth below.  On the date of this Agreement, each of the Purchasers other than
MeriTech agrees to advance to the Company the amount set forth opposite its
respective name on Schedule I, and prior to June 15, 1999, MeriTech agrees to
advance to the Company the amount set forth opposite its name on Schedule I.
MeriTech shall provide the Company two business days notice of the date on which
it shall make the advance.  If MeriTech has not made the advance by June 15,
1999, on that date Oak, Worldview, Accel and Brentwood severally agree to
advance to the Company the additional amount set forth opposite its respective
name on Schedule I.  Each advance of the Loan shall be made by wire transfer of
immediately available funds to the account of the Company specified in Schedule
II hereto.  The Company's obligations to pay the Loan shall be evidenced by the
Company's notes in substantially the form of Exhibit A (each a "NOTE", and
                                             ---------
collectively the "NOTES"). The Notes shall bear interest at a rate of 11% per
annum, which interest shall accrue daily but not compound.   Principal under
each Note will be due and payable on the earlier to occur of (i) the Closing
hereunder and (ii) the date which is 150 days from the date of this Agreement,
or such later date mutually agreed to by the Company and Two-Thirds in Interest
(as hereinafter defined) of the Purchasers (the "FINAL MATURITY DATE"). Such
Final Maturity Date may be accelerated as provided in the Notes.

          Section 1.3.1.  Prepayment. Interest shall be due and payable on any
prepayment of the Note, either in cash or, if at Closing at the Company's
option, in shares of the Company's Series A Preferred Stock (valued at $80.00
per share).

          Section 1.3.2.  Application of Note Proceeds to Purchase Price.   At
the Closing, each Purchaser shall return its outstanding Note to the Company,
and the Company

                                      -2-
<PAGE>

shall cancel each Note and shall apply all amounts outstanding under each Note,
together with all accrued and unpaid interest thereon, to the Purchase Price
payable by the respective Purchaser. If either the Company or a Purchaser so
elects, at the Closing the Company shall pay the accrued and unpaid interest
payable on such Purchaser's Note in cash.

          Section 1.3.3.  Warrants.  On the date of this Agreement, upon its
receipt of the Loan, the Company will issue to each of the Purchasers that has
advanced its portion of the Loan a warrant (each a "WARRANT", and collectively,
the "WARRANTS") to purchase the number of shares of Common Stock set forth
opposite such Purchaser's name on Schedule I, in substantially the form of
Exhibit G.  On the date on which MeriTech advances to the Company its portion of
---------
the Loan, the Company will issue to MeriTech a Warrant to purchase the number of
shares of Common Stock set forth opposite its name on Schedule I or on June 15,
1999, if Oak, Worldview, Accel and Brentwood shall make the additional advances
on the Loan in lieu of MeriTech pursuant to Section 1.3, upon receipt of those
advances the Company will issue to each of Oak, Worldview, Accel and Brentwood
Warrants to purchase the additional number of shares of Common Stock set forth
opposite its respective name on Schedule I under the designation "MeriTech
Warrants."

     Section 1.4. The Closing. Unless this Agreement shall have been terminated
pursuant to Section 6.1, and subject to the satisfaction or waiver of the
conditions set forth in Article V, the consummation of the transactions
contemplated hereby (the "CLOSING") will take place as promptly as practicable
(and in any event within two business days) after satisfaction or waiver of the
conditions set forth in Article V (the "CLOSING DATE"), at the offices of Ropes
& Gray, 885 Third Avenue, New York, New York, unless another date, time or place
is agreed to in writing by the Company and Two-Thirds in Interest of the
Purchasers. At the Closing and subject to the conditions provided herein, the
Company will deliver to each Purchaser a certificate, registered in such
Purchaser's name, representing the number of Shares to be purchased by such
Purchaser hereunder against payment of the aggregate purchase price therefor by
cancellation of the Notes as described in Section 1.3 and by wire transfer of
the remaining amount in immediately available funds to the Company's account as
set forth on Schedule II hereto.


                                  ARTICLE II

                 REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     Subject to Section 7.1 hereof, the Company hereby represents and warrants
to the Purchasers that, except as set forth in the written disclosure schedule
delivered simultaneously with the execution and delivery of this Agreement (the
"COMPANY DISCLOSURE SCHEDULE"):

     Section 2.1.  Organization and Qualification; Subsidiaries.  The Company is
a corporation duly organized, validly existing and in good standing under the
laws of the State of

                                      -3-
<PAGE>

Delaware. Except as set forth in Schedule 2.1, each of the Company's
subsidiaries is a corporation duly organized, validly existing and in good
standing under the laws of the jurisdiction of its incorporation. Except as set
forth in Schedule 2.1, each of the Company and each of its subsidiaries has the
requisite corporate power and authority to own, lease, license, use or operate
the properties it purports to own, operate, license, use or lease and to carry
on its business as it is now being conducted and proposed to be conducted. Each
of the Company and each of its subsidiaries is duly qualified or licensed as a
foreign corporation to do business, and is in good standing, in each
jurisdiction where the character of its properties owned, leased or operated by
it or the nature of its activities makes such qualification or licensing
necessary, except for such failures to be so duly qualified or licensed and in
good standing that do not constitute a Material Adverse Effect.

     Section 2.2.  Certificate of Incorporation and By-Laws.  The Company has
heretofore made available to the Purchasers a complete and correct copy of its
Certificate of Incorporation and By-Laws as most recently restated and
subsequently amended to date.  Except as set forth in Schedule 2.2, such
Certificate of Incorporation and By-Laws, and the certificate of incorporation
and by-laws (or equivalent organizational documents) of each of the Company's
subsidiaries (the "COMPANY SUBSIDIARY DOCUMENTS"), are in full force and effect.
Neither the Company nor any of its subsidiaries is in violation of any of the
provisions of its Certificate of Incorporation or By-Laws or Company Subsidiary
Documents, except for such violations as do not constitute a Material Adverse
Effect.

     Section 2.3.  Capitalization.

          (a)  The authorized capital stock of the Company consists of (i)
     100,000,000 shares of common stock, $0.001 par value per share ("COMMON
     STOCK") and (ii) 10,000,000 shares of preferred stock, $0.001 par value per
     share.  As of May 10, 1999, (i)(A) 1,000,000 shares of preferred stock were
     designated as series of Junior Preferred Stock, none of which were issued
     and outstanding, and (B) 27,200,699 shares of Common Stock were issued and
     outstanding, all of which are duly authorized, validly issued, fully paid
     and nonassessable, and no shares were held in treasury, (ii) 8,051,551
     shares of Common Stock were reserved for future issuance pursuant to stock
     options ("STOCK OPTIONS") or other equity incentives granted or to be
     granted under the Company's Restated Equity Incentive Plan, as amended by
     the Company's Board of Directors (the "BOARD") subject to stockholder
     approval, the Company's 1996 Non-Employee Directors Automatic Stock Option
     Plan or the Company's 1997 Equity Incentive Plan for Non-Employee Directors
     (collectively, the "COMPANY STOCK OPTION PLANS"), (iv) 2,178,490 shares of
     Common Stock were reserved for future issuance upon the exercise of certain
     warrants set forth on Schedule 2.3, and (v) shares of Common Stock were
                           ------------
     reserved for future issuance from time to time as required pursuant to the
     Company's 401(k) Plan.

                                      -4-
<PAGE>

          (b)  On or prior to the Closing Date, the Certificate of Designation
     (as hereinafter defined) will have been duly adopted and filed with the
     Secretary of State of Delaware and, on the Closing Date, shall be in full
     force and effect.  On or prior to the Closing Date, the Company shall
     reserve for issuance the number of shares of Common Stock issuable upon the
     conversion of the Shares issued to the Purchasers pursuant to this
     Agreement.  All shares of Common Stock issuable pursuant to the preceding
     sentence, upon issuance on the terms and conditions specified in the
     instruments pursuant to which they are issuable, will be duly authorized,
     validly issued, fully paid and non assessable.  The Shares issued on the
     Closing Date will, upon payment of the Purchase Price therefor, be duly
     authorized, validly issued, fully paid and nonassessable.

          (c)  As of the date hereof, except as set forth in Schedule 2.3 or the
                                                             ------------
     Company SEC Reports, there are no options, warrants or other rights,
     agreements, arrangements or commitments of any character relating to the
     issued or unissued capital stock of the Company or any of its subsidiaries
     or obligating the Company or any of its subsidiaries to issue or sell any
     shares of capital stock of, or other equity interests in, the Company or
     any of its subsidiaries.  All shares of Common Stock subject to issuance
     thereunder, upon issuance on the terms and conditions specified in the
     instruments pursuant to which they are issuable, will be duly authorized,
     validly issued, fully paid and non-assessable.  Except as set forth in
     Schedule 2.3, there are no obligations, contingent or otherwise, of the
     Company or any of its subsidiaries to repurchase, redeem or otherwise
     acquire any shares of capital stock or the capital stock of any subsidiary
     or to provide funds to or make any investment (in the form of a loan,
     capital contribution or otherwise) in any such subsidiary or any other
     entity other than guarantees of obligations of subsidiaries entered into in
     the ordinary course of business and except for the terms of the Company
     Stock Option Plans.  Except as set forth in Schedule 2.3, all of the
     outstanding shares of capital stock of each of the Company's subsidiaries
     are duly authorized, validly issued, fully paid and nonassessable, and all
     such shares are beneficially owned by the Company or another subsidiary of
     the Company, free and clear of all security interests, liens, claims,
     pledges, agreements, limitations in the Company's voting rights, charges or
     other encumbrances of any nature whatsoever (collectively "LIENS").

          (d)  Except as set forth in Schedule 2.3, there are no outstanding
     bonds, debentures, notes or other indebtedness or other securities of the
     Company having the right to vote (or convertible into, or exchangeable for,
     securities having the right to vote) on any matters on which stockholders
     of the Company may vote.

          (e)  Except for the Transaction Documents (as hereinafter defined) or
     as set forth in Schedule 2.3, the Company is not a party to any agreement
     or arrangement restricting the voting or transfer of any outstanding shares
     of the Common Stock or Preferred Stock of the Company.

                                      -5-
<PAGE>

          (f)  Except as set forth in Schedule 2.3 or in the Transaction
     Documents and as provided by statutes of general application, there are no
     legal, contractual or other restrictions on the payment of dividends or
     other distributions or amounts on or in respect of any of the Common Stock
     or Preferred Stock of the Company.

          (g)  Except as set forth in Schedule 2.3 or in the Transaction
     Documents, there are no agreements or arrangements to which the Company or
     any of its subsidiaries is a party pursuant to which the Company is or
     could be required to register shares of Common Stock or other securities
     under the Securities Act.

          (h)  All outstanding shares of Common Stock and Preferred Stock of the
     Company were issued in compliance with the registration provisions of or
     were exempt from registration under applicable federal and state securities
     laws.

     Section 2.4.  Authority Relative to this Agreement and DGCL Section 203.

          (a)  The Company has all necessary corporate power and authority to
     execute and deliver this Agreement, the Notes, the Registration Rights
     Agreement in the form of Exhibit F hereto among the Company and the
     Purchasers (the "REGISTRATION RIGHTS AGREEMENT"), the Standstill Agreement
     dated as of the date hereof among the Company and the Purchasers (the
     "STANDSTILL AGREEMENT"), and the Warrants (as defined in Section 6.3)
     (collectively, the "TRANSACTION DOCUMENTS"), and to perform its obligations
     under the Transaction Documents and to consummate the transactions
     contemplated thereby.  The execution and delivery of the Transaction
     Documents by the Company and the consummation by the Company of the
     transactions contemplated thereby have been duly and validly authorized by
     all necessary corporate action, and no other corporate proceedings on the
     part of the Company are necessary to authorize or to consummate the
     transactions so contemplated (other than the adoption and filing of the
     Certificate of Designation and the approval of the Stock Purchase by the
     stockholders as contemplated herein).  The Board has determined that it is
     advisable and in the best interest of the Company's stockholders for the
     Company to consummate the Stock Purchase upon the terms and subject to the
     conditions of this Agreement, and, except for Messrs. Fillat and Murray,
     who abstained, has unanimously recommended that the Company's stockholders
     approve and adopt this Agreement.  Each of the Transaction Documents has
     been duly and validly executed and delivered by the Company and, assuming
     the due authorization, execution and delivery by the Purchasers,
     constitutes a legal, valid and binding obligation of the Company
     enforceable against the Company in accordance with its terms, except that
     (i) such enforcement may be subject to bankruptcy, insolvency,
     reorganization, moratorium or other similar laws now or hereafter in effect
     relating to creditors' rights, (ii) the remedy of specific performance and
     injunctive and other forms of equitable relief may be subject to equitable
     defenses and to the discretion of the court before which any proceeding
     therefor may be brought,

                                      -6-
<PAGE>

     and (iii) the enforcement of the indemnification provisions contained in
     the Registration Rights Agreement are subject to applicable securities laws
     and principles of public policy.

          (b)  The Board has taken all actions so that the restrictions
     contained in Section 203 of the Delaware General Corporation Law, as from
     time to time in effect, applicable to a "business combination" (as defined
     in Section 203) will not apply to the execution, delivery or performance of
     this Agreement by the interested stockholders (as defined in Section 203)
     or their consummation of the transactions contemplated hereby.

     Section 2.5.  No Conflict; Required Filings and Consents.

          (a)  The Company has made available to the Purchasers copies of (i)
     all loan agreements, indentures, mortgages, pledges, conditional sale or
     title retention agreements, security agreements, equipment obligations,
     guaranties, standby letters of credit, equipment leases or lease purchase
     agreements to which the Company or any of its subsidiaries is a party or by
     which any of them is bound, each in a principal outstanding amount equal to
     or exceeding $2,000,000, but excluding any such agreement between the
     Company and its wholly-owned subsidiaries or between two or more wholly-
     owned subsidiaries of the Company; (ii) all contracts, agreements,
     commitments or other understandings or arrangements to which the Company or
     any of its subsidiaries is a party or by which any of them or any of their
     respective properties or assets are bound or affected, but excluding
     contracts, agreements, commitments or other understandings or arrangements
     entered into in the ordinary course of business and involving, in each
     case, aggregate payments or receipts by the Company or any of its
     subsidiaries of less than $2,000,000 in any single instance; and (iii) all
     agreements which, as of the date hereof, are required to be filed by the
     Company as "material contracts" with the Securities Exchange Commission
     ("SEC") pursuant to the requirements of the Securities Exchange Act of
     1934, as amended, and the SEC's rules and regulations thereunder (the
     "EXCHANGE ACT") (collectively, the "MATERIAL CONTRACTS").  Schedule 2.5
     sets forth a correct and complete list of the Material Contracts.

          (b)  Except as set forth in Schedule 2.5, (i) neither the Company nor
     any of its subsidiaries has breached, is in default under, or has received
     written notice of any breach of or default under, any Material Contract,
     (ii) to the knowledge of the Company, no other party to any of the Material
     Contracts has breached or is in default of any of its obligations
     thereunder, and (iii) each of the Material Contracts is in full force and
     effect and constitutes a legal, valid and binding obligation of the parties
     thereto enforceable against such parties in accordance with its terms,
     except in any such case for breaches, defaults or failures to be in full
     force and effect that do not constitute a Material Adverse Effect.  Except
     as set forth in Schedule 4.7, the execution and delivery of this Agreement
     by the Company does not, and the performance of this

                                      -7-
<PAGE>

     Agreement by the Company will not, constitute a breach of or default under
     any Material Contract, or require any consent pursuant to any Material
     Contract, except where the failure to obtain such consent does not
     constitute a Material Adverse Effect or materially adversely affect the
     Purchasers with respect to their rights under the Transaction Documents.

          (c)  The execution and delivery of this Agreement by the Company does
     not, and the performance of this Agreement by the Company and the
     consummation of the transactions contemplated hereby will not, (i) conflict
     with or violate the Certificate of Incorporation or By-Laws of the Company,
     (ii) conflict with or violate any federal, foreign, state or provincial
     law, rule, regulation, order, judgment or decree (collectively, "LAWS")
     applicable to the Company or any of its subsidiaries or by which its or any
     of their respective properties are bound or affected, or (iii) except as
     set forth on Schedule 4.7, result in any breach of or constitute a default
     (or an event that with notice or lapse of time or both would become a
     default under), or impair the Company's or any of its subsidiaries' rights
     or alter the rights or obligations of any third party under, or give to
     others any rights of termination, amendment, acceleration or cancellation
     of, or result in the creation of a Lien on any of the properties or assets
     of the Company or any of its subsidiaries pursuant to any Material
     Contract, except in any such case for any such conflicts, violations,
     breaches, defaults or other occurrences that do not constitute a Material
     Adverse Effect.

          (d)  Except as set forth on Schedule 2.5, the execution and delivery
     of this Agreement by the Company does not, and the performance of this
     Agreement by the Company will not, require any consent, approval,
     authorization or permit of, or filing with or notification to, any federal,
     foreign, state or provincial governmental or regulatory authority except
     (i) for applicable requirements, if any, of the Securities Act, the
     Exchange Act, state securities laws ("BLUE SKY LAWS") and the pre-merger
     notification requirements of the Hart-Scott-Rodino Antitrust Improvements
     Act of 1976, as amended (the "HSR ACT"), (ii) applicable requirements of
     the Communications Act (as hereinafter defined) and the FCC (as hereinafter
     defined), (iii) filing of the Certificate of Designation, and (iv) where
     the failure to obtain such consents, approvals, authorizations or permits,
     or to make such filings or notifications, would not prevent or delay
     consummation of the Closing, or otherwise prevent or delay the Company from
     performing its obligations under this Agreement, or would not otherwise
     have a Material Adverse Effect.

     Section 2.6  Compliance.

          (a)  Neither the Company nor any of its subsidiaries is in conflict
     with, or in default or violation of, (i) any Law applicable to the Company
     or any of its subsidiaries or by which its or any of their respective
     properties are bound or affected or (ii) any

                                      -8-
<PAGE>

     Material Contract, except for any such conflicts, defaults or violations
     which do not constitute a Material Adverse Effect.

          (b)  Each of the Company and its subsidiaries has filed or caused to
     be filed with each applicable Governmental Body all reports, applications,
     documents, instruments and information required to be filed by it pursuant
     to all applicable laws, rules, regulations, ordinances, judgment, decrees,
     rulings, orders, awards, injunctions, recommendations or other official
     actions of any Governmental Body, other than those as to which the failure
     to file do not constitute a Material Adverse Effect.

     Section 2.7.  SEC Filings; Financial Statements.

          (a)  The Company has filed with the Securities and Exchange Commission
     all reports, schedules, forms, statements and other documents required by
     the Securities Act or the Exchange Act to be filed by the Company since
     January 1, 1998 as filed on or before the date of this Agreement
     (collectively, and in each case including all exhibits and schedules
     thereto and documents incorporated by reference therein the "COMPANY SEC
     REPORTS").  Schedule 2.7 sets forth a list of all Company SEC Reports.  As
     of their respective dates (except if revised or superseded by a subsequent
     filing on or before the date of this Agreement, as of such date), the
     Company SEC Reports (including the financial statements included therein)
     (i) complied as to form in all material respects with the requirements of
     the Securities Act or the Exchange Act, as the case may be, and the rules
     and regulations thereunder, and  (ii) did not contain any untrue statement
     of a material fact or omit to state a material fact required to be stated
     therein or necessary in order to make the statements therein, in light of
     the circumstances under which they were made, not misleading.  The Company
     has filed with the Securities and Exchange Commission as exhibits to the
     Company SEC Reports all agreements, contracts and other documents or
     instruments required to be so filed, and such exhibits are in all material
     respects true and complete copies of such agreements, contracts and other
     documents or instruments, as the case may be (subject to any confidential
     treatment requests allowing excision of confidential information from the
     publicly filed document).  None of the subsidiaries of the Company is
     required to file any reports, schedules, statements or other documents with
     the Securities and Exchange Commission.

          (b)  The consolidated balance sheets of the Company and its
     consolidated subsidiaries as of each of December 31, 1998 and March 31,
     1999 and the related consolidated statements of income (loss) and
     stockholders' equity and cash flows for the 12 month period and three month
     period then ended, true and complete copies of which have been delivered to
     the Purchasers, fairly present the consolidated financial position of the
     Company and its consolidated subsidiaries as of their respective dates and
     their consolidated results of operations and cash flows for the respective
     periods then ended, in accordance with U.S. generally accepted accounting
     principles applied on a consistent

                                      -9-
<PAGE>

     basis except as described in the footnotes to the financial statements or
     as disclosed in Schedule 2.7.

          (c)  The Company has made available to the Purchasers copies of each
     management letter delivered to any of the Company and its subsidiaries by
     PricewaterhouseCoopers LLP in connection with the financial statements
     referred to in this Section 2.7 or relating to any review by them of the
     internal controls of the Company and its subsidiaries during the twelve
     months ended December 31, 1998 or thereafter, and has made available for
     inspection for the twelve month period ended December 31, 1998 and, subject
     to the approval of PricewaterhouseCoopers LLP, after the date of this
     Agreement will make available for inspection all reports and working papers
     produced or developed by them or management in connection with their
     examination of those financial statements and the other financial
     statements for the three years then ended, as well as all such reports and
     working papers for prior periods for which any liability of any of the
     Company and its subsidiaries for Taxes (as hereinafter defined) has not
     been finally determined or barred by applicable statutes of limitation.

          (d)  Since January 1, 1998, to the knowledge of the Company, there has
     been no material disagreement (within the meaning of Item 304(a)(1)(iv) of
     Regulation S-K under the Securities Act) between the Company and its
     independent accountants with respect matters of accounting principles or
     practices, financial statement disclosure or auditing scope or procedures
     which if not resolved to the satisfaction of such accountant would cause it
     to make a reference to the subject matter of the disagreements in
     connection with its report.

     Section 2.8.  Absence of Certain Changes or Events.  Except as set forth in
Schedule 2.8 or in the Company SEC Reports or as contemplated by this Agreement,
since December 31, 1998, the Company has conducted its business in the ordinary
course and there has not occurred: (a) any Material Adverse Effect; (b) any
amendments or changes in the Certificate of Incorporation or By-Laws of the
Company; (c) any damage to, destruction or loss of any asset of the Company
(whether or not covered by insurance) that could reasonably be expected to have
a Material Adverse Effect; (d) any material change by the Company in its
accounting methods, principles or practices; (e) any material revaluation by the
Company of any of its assets, including, without limitation, writing down the
value of inventory or writing off notes or accounts receivable other than in the
ordinary course of business; or (f) any sale of a material amount of property of
the Company or any of its subsidiaries, except in the ordinary course of
business.

     Section 2.9.  No Undisclosed Liabilities.  Except as set forth in the
Company SEC Reports or on Schedule 2.9, neither the Company nor any of its
subsidiaries has any liabilities (absolute, accrued, contingent or otherwise),
except liabilities (a) in the aggregate adequately provided for in the Company's
audited balance sheet (including any related notes thereto) for the fiscal year
ended December 31, 1998 included in the Company SEC Reports (the "1998

                                      -10-
<PAGE>

COMPANY BALANCE SHEET"), (b) incurred in the ordinary course of business and not
required under U.S. generally accepted accounting principles to be reflected on
the 1998 Company Balance Sheet, (c) incurred since December 31, 1998 in the
ordinary course of business consistent with past practice, (d) incurred in
connection with this Agreement, or (e) which do not constitute a Material
Adverse Effect.

     Section 2.10.  Absence of Litigation.  There are no claims, actions, suits,
proceedings or investigations pending or, to the knowledge of the Company,
threatened against the Company or any of its subsidiaries, or any properties or
rights of the Company or any of its subsidiaries, before any federal, foreign,
state or provincial court, arbitrator or administrative, governmental or
regulatory authority or body that could reasonably be expected to have a
Material Adverse Effect.

     Section 2.11.  Employee Benefit Plans.  Except as set forth in Schedule
2.11 and in the Company SEC Reports:

          (a)  The Company and its subsidiaries are not and have not been
     required to contribute to any employee benefit plan or any other profit
     sharing, stock option, stock purchase, stock appreciation, deferred
     compensation, severance, or other material plan or arrangement for the
     benefit of the Company, its subsidiaries and current or former directors,
     officers, or employees (collectively "EMPLOYEE PLANS").

          (b)  None of the Company and its subsidiaries has incurred, or has any
     reason to expect that it will incur, any liability to the Pension Benefit
     Guaranty Corporation (other than premium payments) or otherwise under Title
     IV of the Employee Retirement Income Security Act of 1974, as amended
     ("ERISA") (including any withdrawal liability) or under the Internal
     Revenue Code of 1986, as amended (the "CODE") with respect to any such
     employee benefit plan which is an employee pension benefit plan.

          (c)  Each Employee Plan maintained by the Company is, and has been at
     all times, maintained and operated in compliance with all statutes, orders
     or governmental rules or regulations, including but not limited to ERISA,
     the Code and applicable federal or state securities laws, and any and all
     collective bargaining agreements and other contracts applicable thereto and
     there have been no acts or omissions by the Company, its subsidiaries or
     its officers which have given rise to or could reasonably be expected to
     give rise to fines, penalties, taxes or related charges or liability under
     ERISA or the Code, except where such charges and liabilities do not
     constitute a Material Adverse Effect.

          (d)  All plans and related trusts that are intended to qualify under
     Sections 401(a) and 501(a) of the Code, have been determined by the
     Internal Revenue Service

                                      -11-
<PAGE>

     to be so qualified, and copies of such determination letters have been made
     available to the Purchasers.

     Section 2.12.  Proxy Statement.  The information supplied by the Company
for inclusion in the proxy statement to be sent to the stockholders of the
Company in connection with the meeting of the stockholders of the Company to
consider the sale of the Shares (the "STOCKHOLDERS MEETING") (such proxy
statement as amended or supplemented is referred to herein as the "PROXY
STATEMENT"), will not, on the date the Proxy Statement (or any amendment thereof
or supplement thereto) is first mailed to stockholders or at the time of the
Stockholders Meeting, contain any untrue statement of a material fact, or shall
omit to state any material fact necessary in order to make the statements made
therein not false or misleading, or omit to state any material fact necessary to
correct any statement in any earlier communication with respect to the
solicitation of proxies for the Stockholders Meeting which has become false or
misleading. If at any time prior to the Closing Date any event relating to the
Company or any of its affiliates, officers or directors should be discovered by
the Company which is required to be set forth in a supplement to the Proxy
Statement, the Company shall promptly inform the Purchasers and shall amend such
Proxy Statement to correct such omission. Notwithstanding the foregoing, the
Company makes no representation or warranty with respect to any statement or
omission based on information supplied by the Purchasers which is contained in
any of the foregoing documents.

     Section 2.13.  Title to Property.

          (a)  Except as set forth in Schedule 2.13 or in the Company SEC
     Reports, the Company and each of its subsidiaries have good and marketable
     title to all of their properties and assets, free and clear of all liens,
     charges and encumbrances, except liens for taxes not yet due and payable
     and such liens or other imperfections of title which do not constitute a
     Material Adverse Effect; and, to the knowledge of the Company, all leases
     pursuant to which the Company or any of its subsidiaries lease from others
     material amounts of real or personal property, are in good standing, valid
     and effective in accordance with their respective terms, and there is not,
     to the knowledge of the Company, under any of such leases, any existing
     default or event of default (or event which with notice or lapse of time,
     or both, would constitute a default), except where such default or event of
     default does not constitute a Material Adverse Effect.

          (b)  All tangible Company properties are in such condition and repair,
     and are suitable, sufficient in amount, size and type and so situated, as
     is appropriate and adequate for the uses for which they are used and
     intended and to carry on the business of the Company or such subsidiary, as
     the case may be, as now conducted.

     Section 2.14.   Restrictions on Business Activities.  Except as set forth
in the Company SEC Reports or on Schedule 2.14, to the Company's knowledge,
there is no agreement,

                                      -12-
<PAGE>

judgment, injunction, order or decree binding upon the Company or any of its
subsidiaries which has or could reasonably be expected to have the effect of
prohibiting or impairing any business practice of the Company or any of its
subsidiaries, acquisition of property by the Company or any of its subsidiaries
or the conduct of business by the Company or any of its subsidiaries as
currently conducted or as proposed to be conducted by the Company, except for
any prohibition or impairment as does not constitute a Material Adverse Effect.

     Section 2.15.  Taxes.

          (a)  For purposes of this Agreement, "TAX" or "TAXES" shall mean
     taxes, fees, levies, duties, tariffs, imposts, and governmental impositions
     or charges of any kind in the nature of (or similar to) taxes, payable to
     any federal, state, local or foreign taxing authority, including (without
     limitation) (i) income, franchise, profits, gross receipts, ad valorem, net
     worth, value added, sales, use, service, real or personal property, special
     assessments, capital stock, license, payroll, withholding, employment,
     social security, workers' compensation, unemployment compensation, utility,
     severance, production, excise, stamp, occupation, premiums, windfall
     profits, transfer and gains taxes, and (ii) interest, penalties, additional
     taxes and additions to tax imposed with respect thereto; and "TAX RETURNS"
     shall mean returns, reports, and information statements with respect to
     Taxes required to be filed with the Internal Revenue Service or any other
     federal, foreign, state or provincial taxing authority, domestic or
     foreign, including, without limitation, consolidated, combined and unitary
     tax returns.

          (b)   Except as set forth in the Company SEC Reports: (i) The Company
     and its subsidiaries have filed all Tax Returns required to be filed by
     them, except where the failure to file a Tax Return does not constitute a
     Material Adverse Effect and (ii) the Company and its subsidiaries have paid
     all Taxes covered by such Tax Returns and have paid all other Taxes as are
     due, except those with respect to which the Company is maintaining adequate
     reserves, unless the failure to do so does not constitute a Material
     Adverse Effect.  Except as set forth in the Company SEC Reports or except
     as does not involve or would not result in liability to the Company or any
     of its subsidiaries that could reasonably be expected to have a Material
     Adverse Effect:  (i) there are no tax liens on any assets of the Company or
     any subsidiary thereof; and (ii) neither the Company nor any of its
     subsidiaries has granted any waiver of any statute of limitations with
     respect to, or any extension of a period for the assessment of, any Tax.
     The accruals and reserves for Taxes (including deferred taxes) reflected in
     the 1998 Company Balance Sheet are in all material respects adequate to
     cover all Taxes required to be accrued through the date thereof (including
     interest and penalties, if any, thereon and Taxes being contested) in
     accordance with U.S. generally accepted accounting principles.

     Section 2.16.  Environmental Matters.  Except in all cases as, in the
aggregate, do not constitute a Material Adverse Effect, and except for any
matters as to which remediation

                                      -13-
<PAGE>

efforts have been completed, the Company and each of its subsidiaries to the
Company's knowledge: (i) have obtained all franchises, grants, authorizations,
licenses, permits, consents, approvals and orders ("APPROVALS") which are
required to be obtained under all applicable federal, state, foreign or local
laws or any regulation, code, plan, order, decree, judgment, notice or demand
letter issued, entered, promulgated or approved thereunder relating to pollution
or protection of the environment, including laws relating to emissions,
discharges, releases or threatened releases of pollutants, contaminants, or
hazardous or toxic materials or wastes into ambient air, surface water, ground
water, or land or otherwise relating to the manufacture, processing,
distribution, use, treatment, storage, disposal, transport, or handling of
pollutants, contaminants or hazardous or toxic materials or wastes by the
Company or its subsidiaries or their respective agents ("ENVIRONMENTAL LAWS");
(ii) each of such Approvals is in full force and effect and each of the Company
and each of its subsidiaries in compliance with all terms and conditions of such
required Approvals and also is in compliance with all other limitations,
restrictions, conditions, standards, prohibitions, requirements, obligations,
schedules and timetables contained in applicable Environmental Laws; (iii) as of
the date hereof, are not aware of nor have received notice of any past or
present violations of Environmental Laws or any event, condition, circumstance,
activity, practice, incident, action or plan which is reasonably likely to
interfere with or prevent continued compliance with or which would give rise to
any common law or statutory liability, or otherwise form the basis of any claim,
action, suit or proceeding, against the Company or any of its subsidiaries based
on or resulting from the manufacture, processing, distribution, use, treatment,
storage, disposal, transport or handling, or the emission, discharge or release
into the environment, of any pollutant, contaminant or hazardous or toxic
material or waste; and (iv) have taken all actions necessary under applicable
Environmental Laws to register any products or materials required to be
registered by the Company or its subsidiaries (or any of their respective
agents) thereunder.

     Section 2.17.  Intellectual Property.

          (a)  To its knowledge, the Company, directly or indirectly, owns, or
     is licensed or otherwise possesses (or has applied for), legally
     enforceable rights to use, all copyrights, uncopyrighted works, trademarks,
     trademark rights, service marks, trade names, trade name rights, patents,
     patent rights, unpatented inventions, licenses, permits, trade secrets,
     know-how, inventions, computer software, seismic data and intellectual
     property rights and other proprietary rights together with applications and
     licenses for any of the foregoing (the "COMPANY INTELLECTUAL PROPERTY
     RIGHTS"), except where the failure to so own, be licensed or otherwise
     possess legally enforceable rights to use does not constitute a Material
     Adverse Effect.

          (b)   No claims with respect to the Company Intellectual Property
     Rights have been asserted or, to the knowledge of the Company, are
     threatened by any person, that reasonably would be expected to have a
     Material Adverse Effect on the Company or any of its subsidiaries, (i) to
     the effect that the manufacture, sale, licensing or use of

                                      -14-
<PAGE>

     any of the products of the Company or any of its subsidiaries as now
     manufactured, sold or licensed or used or currently proposed for
     manufacture, use, sale or licensing by the Company or any of its
     subsidiaries infringes on any copyright, patent, trademark, service mark or
     trade secret, (ii) against the use by the Company or any of its
     subsidiaries of any material trademarks, service marks, trade names, trade
     secrets, copyrights, patents, technology, know-how or computer software
     programs and applications used in the business of the Company and its
     subsidiaries as currently conducted, or (iii) challenging the ownership,
     validity or effectiveness of any of the Company Intellectual Property
     Rights. All registered trademarks, service marks and copyrights held by the
     Company are valid and subsisting. To the knowledge of the Company, there is
     no unauthorized use, infringement or misappropriation of any of the Company
     Intellectual Property Rights by any third party, including any employee or
     former employee of the Company or any of its subsidiaries, which could
     reasonably be expected to have a Material Adverse Effect. No Company
     Intellectual Property Right or product of the Company or any of its
     subsidiaries is subject to any outstanding decree, order, judgment, or
     stipulation restricting in any manner the licensing thereof by the Company
     or any of its subsidiaries.

          (c)  To the best of the Company's knowledge, none of the hardware or
     software currently owned, leased or licensed by the Company and used or
     proposed to be used in the business and operations of any of the Company
     and its subsidiaries contains imbedded logic or code that will fail to
     recognize the year 2000 as such, or that might fail or cause other hardware
     or software to cease to perform according to specifications or to the needs
     of the business of the Company or the subsidiary, as the case might be, by
     reason of the date change after December 31, 1999, except where such
     condition does not constitute a Material Adverse Effect.

     Section 2.18.  Certain Agreements of Officers and Employees. To the
Company's knowledge, no employee of the Company is, or is now expected to be, in
violation of any term of any employment contract, patent disclosure agreement,
non-competition agreement, or any other contract or agreement or any restrictive
covenant relating to the right of any such officer or employee to be employed by
the Company because of the nature of the business conducted or to be conducted
by the Company or relating to the use of trade secrets or propri etary
information of others.

     Section 2.19.  Regulatory Matters  Except to the extent as would not have a
Material Adverse Effect and except as set forth in Schedule 2.19:

          (a)  The Company and its subsidiaries are in compliance with the
     Communications Act of 1934, as amended by the Telecommunications Act of
     1996 (the "COMMUNICATIONS ACT") and with all applicable rules, regulations
     and policies of the Federal Communications Commission (the "FCC").

                                      -15-
<PAGE>

          (b)  Schedule 2.19 sets forth a complete and accurate list of all
     licenses (the "FCC LICENSES") granted to the Company and its subsidiaries
     by the FCC.  All the FCC Licenses are currently valid and in full force and
     effect and the Company and its subsidiaries have met material applicable
     construction or build-out regulations required to be met as of this date
     for each of the FCC Licenses.  Neither the Company nor any of its
     subsidiaries has received any notification of an investigation, violation
     or forfeiture, any notice of apparent liability, or any other order or
     complaint issued by or before any court or governmental body, including the
     FCC that could in any manner threaten or adversely affect the validity,
     continued effectiveness, material terms, or likelihood of renewal of any of
     the FCC Licenses, nor to the knowledge of the Company is any such action
     threatened.  Neither the Company nor any of its subsidiaries has knowledge
     of any other proceedings (other than proceedings relating to the wireless
     communications or 38 GHz industries generally) that could in any manner
     threaten or adversely affect the validity, continued effectiveness,
     material terms, or likelihood of renewal of any of the FCC Licenses.

          (c)  No event has occurred or failed to occur which (i) results in, or
     after notice or lapse of time or both would result in, revocation,
     suspension, adverse modification, non-renewal, impairment, restriction or
     termination of, or order of forfeiture with respect to, any FCC License or
     (ii) adversely affects or could reasonably be expected in the future to
     adversely affect any of the rights of the Company or any of its
     subsidiaries thereunder except for legislation or rule making of general
     applicability.

          (d)  The Company and its subsidiaries have duly filed in a timely
     manner all filings, reports, applications, documents, instruments and
     information required to be filed by them under the Communications Act or
     the applicable rules, regulations and policies of the FCC, and all such
     filings are true, correct and complete in all material respects.

          (e)  Neither the Company nor any of its subsidiaries has any reason to
     believe that any of the FCC Licenses will not be renewed in the ordinary
     course.

     Section 2.20.  Rank of Notes.  The Notes rank and will rank on a parity in
right of payment with all senior indebtedness of the Company outstanding on the
date hereof or that may be incurred hereafter.

     Section 2.21.  Interested Party Transactions.  Except as contemplated by
this Agreement or as set forth on Schedule 2.21, since December 31, 1998, no
event has occurred that would be required to be reported as a Certain
Relationship or Related Transaction pursuant to Item 404 of Regulation S-K
promulgated by the SEC.

     Section 2.22.  Insurance.  The Company and its subsidiaries maintain in
full force and effect insurance policies with reputable insurance carriers. Such
policies provide adequate

                                      -16-
<PAGE>

coverage for all normal risks incident to the business of the Company and its
subsidiaries and their respective properties and assets and are in character and
amount similar to that carried by entities engaged in similar businesses and
subject to the same or similar perils or hazards, except as do not constitute a
Material Adverse Effect.

     Section 2.23.  Brokers.  No broker, finder or investment banker (other than
Morgan Stanley & Co. Incorporated ("MORGAN STANLEY"), the fees and expenses of
which will be paid by the Company) is entitled to any brokerage, finder's or
other fee or commission in connection with the transactions contemplated by this
Agreement based upon arrangements made by or on behalf of the Company or its
subsidiaries or affiliates.  The Company has heretofore made available to the
Purchasers a complete and correct copy of all agreements between the Company and
Morgan Stanley pursuant to which such firm would be entitled to any payment
relating to the transactions contemplated hereunder.

     Section 2.24.  Disclosure.  This agreement including the schedules and
exhibits hereto and the certificates delivered hereunder does not, and at
Closing will not, contain any untrue statement of a material fact, or omit to
state a material fact necessary to make the statements herein, in light of the
circumstances under which they were made, not misleading.  With respect to
projections contained in the Business Strategy Plan (as hereinafter defined),
the Company notes that actual results may vary materially from the projections
and represents only that such projections were prepared in good faith and are
based on a set of assumptions believed by the Company to be reasonable as of the
date hereof.

     Section 2.25.  Securities Laws.  Assuming that each of the Purchaser's
representations and warranties contained in Article III hereof are, and continue
to be at the Closing Date and at the date of exercise of the Warrants, true and
correct, the issuance and sale of the Notes and the Warrants are as of the date
hereof, and the issuance and sale of the Shares on the Closing Date will be, and
the issuance of the shares of Common Stock upon conversion of the Preferred
Stock will be, exempt from the registration and prospectus delivery requirements
of the Securities Act and from registration and qualification under applicable
Blue Sky Laws.

     Section 2.26.  Acquiring Person.  Assuming that each of the Purchaser's
representations and warranties contained in Article III hereof are at the
Closing Date true and correct, at the Closing Date no Purchaser will constitute
an Acquiring Person as defined in the Rights Agreement dated as of June 20, 1997
between the Company and BankBoston, NA as Rights Agent.

     Section 2.27.  Acceleration.  Except as set forth on Schedule 2.27, the
execution and performance of this Agreement will not in and of itself result in
the acceleration of the vesting of any options issued by the Company or the
payments by the Company to any employee, officer or director.

                                      -17-
<PAGE>

     Section 2.28.   Board of Directors.  Schedule 2.28 sets forth the Company's
directors as of the date hereof, and the nominating class of each such director.


                                  ARTICLE III

                REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS

     Subject to Section 7.1 hereof, each of the Purchasers severally represents
and warrants to the Company that:

     Section 3.1.  Organization.  Such Purchaser is duly organized, validly
existing and in good standing under the laws of the  jurisdiction of its
organization, with all requisite power and authority to own, lease and operate
its properties and to conduct its business as now being conducted.

     Section 3.2.  Due Authorization.  Such Purchaser has all right, power and
authority to enter into this Agreement, the Registration Rights Agreement and
the Standstill Agreement and to consummate the transactions contemplated hereby
and thereby.  The execution and delivery of this Agreement, the Registration
Rights Agreement and the Standstill Agreement by such Purchaser and the
consummation by such Purchaser of the transactions contemplated hereby and
thereby have been duly authorized by all necessary action on behalf of such
Purchaser. Each of this Agreement, the Registration Rights Agreement and the
Standstill Agreement has been duly executed and delivered by such Purchaser and
constitutes the valid and binding agreement of such Purchaser enforceable in
accordance with its terms, except that (i) such enforcement may be subject to
bankruptcy, insolvency, reorganization, moratorium or other similar laws now or
hereafter in effect relating to creditors' rights, (ii) the remedy of specific
performance and injunctive and other form of equitable relief may be subject to
equitable defenses and to the discretion of the court before which any
proceeding therefor may be brought, and (iii) the enforcement of the
indemnification provisions contained in the Registration Rights Agreement are
subject to applicable securities laws and principles of public policy.

     Section 3.3.  Acquisition for Investment.  Such Purchaser is acquiring the
Shares being purchased by it for its own account for the purpose of investment
and not with a view to or for sale in connection with any distribution thereof,
and such Purchaser has no present intention or plan to effect any distribution
of Shares other than pursuant to Rule 144A under the Securities Act or in an
offering registered under the Securities Act.  Such Purchaser does not have any
contract, undertaking, agreement or arrangement with any person to sell,
transfer, or grant participations to such person or to any third person, with
respect to any of the Shares.

     Section 3.4.  Brokers or Finders.  No agent, broker, investment banker or
other firm or Person acting on behalf of such Purchaser, including any of the
foregoing that is an affiliate of

                                      -18-
<PAGE>

such Purchaser, is or will be entitled to any broker's or finder's fee or any
other commission or similar fee in connection with any of the transactions
contemplated by this Agreement.

     Section 3.5.  Accredited Investor.  Such Purchaser is an "accredited
investor" within the meaning of Regulation D under the Securities Act.

     Section 3.6.  Financial Condition.  Such Purchaser's financial condition is
such that it is able to bear the risk of holding the Shares for an indefinite
period of time and can bear the loss of its entire investment in the Shares.

     Section 3.7.  Experience.  Such Purchaser has such knowledge and experience
in financial and business matters and in making high risk investments of this
type that it is capable of evaluating the merits and risks of the purchase of
Shares.

     Section 3.8. Non-U.S. Ownership. To the knowledge of such Purchaser, except
as set forth on Schedule 3.8, the percentage of the capital stock or ownership
or voting interests of such Purchaser that, for purposes of Section 3.10(b) of
the Communications Act is owned or voted, directly or indirectly, beneficially
or otherwise, by foreign entities or persons, does not exceed 25%.

     Section 3.9.  Beneficial Ownership.  Each Purchaser that is a party to the
Standstill Agreement represents that as of the date hereof it has not entered
into any agreement, other than the "Stockholders Agreement" (as defined in the
Standstill Agreement) and the Transaction Documents, with respect to the
acquisition, voting or disposition of the Shares with any party.

     Section 3.10.  Affiliates.  Except for securities such Purchaser has agreed
to purchase hereunder or as set forth on Schedule III, such Purchaser does not
beneficially own, directly or indirectly, beneficially, any of the Company's
capital stock.

     Section 3.11.  Proxy Statement.  The information supplied by such Purchaser
in writing specifically for inclusion in the Proxy Statement will not, on the
date the Proxy Statement (or any amendment thereof or supplement thereto) is
first mailed to stockholders or at the time of the Stockholders Meeting, contain
any untrue statement of a material fact, or shall omit to state any material
fact necessary in order to make such information not false or misleading.  If at
any time prior to the Closing Date any event relating to such Purchaser or any
of its affiliates, officers or directors should be discovered by such Purchaser
which is required to be set forth in a supplement to the Proxy Statement, such
Purchaser shall promptly inform the Company.

                                      -19-
<PAGE>

                                  ARTICLE IV

                             ADDITIONAL AGREEMENTS

     The Company and each of the Purchasers severally agree that:

     Section 4.1.  HSR Act.  As promptly as practicable after the date of the
execution of this Agreement, the Company, those Purchasers required by law to
file and all other necessary parties shall file notifications under and in
accordance with the HSR Act in connection with the Stock Purchase and the
transactions contemplated hereby and shall respond as promptly as practicable to
any inquiries and requests received (i) from the Federal Trade Commission (the
"FTC") and the Antitrust Division of the Department of Justice (the "ANTITRUST
DIVISION") for additional information or documentation or (ii) from any State
Attorney General or other governmental authority in connection with antitrust
matters.

     Section 4.2.  Proxy Statement.  Unless the Closing is to occur without a
vote of the Company's stockholders, the Company shall use its best efforts, to
prepare and file with the SEC as promptly as possible preliminary proxy
materials seeking stockholder approval of the Stock Purchase (the "PROXY
STATEMENT").   The Purchasers shall use their best efforts to furnish the
Company such information about the Purchasers and the directors proposed by the
Purchasers as may be necessary to prepare and file the definitive Proxy
Statement on such schedule.   As promptly as practicable after comments are
received from the SEC thereon and after the furnishing by the Company and the
Purchasers of all information required to be contained therein, the Company
shall use its reasonable best efforts to mail the Proxy Statement to its
stockholders, as soon thereafter as practicable.  The Proxy Statement shall
include the recommendation of the Board in favor of the Stock Purchase, subject
to Section 4.4.

     Section 4.3.  Stockholders Meeting.  Unless the Closing is to occur without
a vote of the Company's stockholders, the Company shall call and hold its
Stockholders Meeting as promptly as practicable and in accordance with
applicable laws for the purpose of voting upon the approval of the Stock
Purchase.  Except as contemplated by Section 4.4, the Company shall use all
reasonable efforts to solicit from its stockholders proxies in favor of adoption
of this Agreement and approval of the transactions contemplated hereby and shall
take all other action necessary or advisable to secure the vote or consent of
stockholders to obtain such approvals.

     Section 4.4.  Alternative Transactions.  The Company shall not, or permit
any of its officers, directors, employees, financial advisors and other
representatives on behalf of the Company to:

               (1) enter into any agreement or other arrangement with respect
     to, or take any other action to effect, any Alternative Transaction (as
     hereinafter defined);

                                      -20-
<PAGE>

               (2) solicit, initiate or encourage (including, without
     limitation, by way of furnishing information), or take any other action to
     facilitate, any inquiry or the making of any proposal to any of the
     Company, its subsidiaries and its stockholders from any person which
     constitutes, or may reasonably be expected to lead to, a proposal with
     respect to an Alternative Transaction with respect to any of the Company
     and its subsidiaries, or endorse any Alternative Transaction; or

               (3) continue, enter into or participate in any activities,
     discussions or negotiations regarding any of the foregoing, or furnish to
     any other person any information with respect to the business, properties,
     operations, prospects or condition (financial or otherwise) of any of the
     Company and its subsidiaries or any of the foregoing, or otherwise
     cooperate in any way with, or assist or participate in, facilitate or
     encourage, any effort or attempt by any other person to do or seek to do
     any of the foregoing;

provided, that this Section 4.4 shall not prohibit (i) the Company from (A)
--------
furnishing to any person that has made an unsolicited, bona fide written
proposal with respect to an Alternative Transaction information concerning the
Company and its subsidiaries and the business, properties, operations, prospects
or condition (financial or otherwise) of the Company and its subsidiaries or (B)
engaging in discussions or negotiations with such person that has made such
written proposal with respect to an Alternative Transaction, (ii) following
receipt of such written proposal with respect to an Alternative Transaction, the
Company from taking and disclosing to its stockholders a position contemplated
by Rule 14e-2(a) under the Exchange Act, (iii) following receipt of such written
proposal with respect to an Alternative Transaction, the Board from withdrawing
or modifying the Board's approval of the Stock Purchase, or (iv) the Board from
recommending that the stockholders of the Company accept and approve such
proposal with respect to an Alternative Transaction or authorizing, recommending
or proposing an agreement with respect to such written proposal; provided,
                                                                 --------
however, that the Company or the Board, as the case may be, shall (w) take any
-------
action referred to in the preceding clause (iv) only after the Company gives the
Purchasers two business days advance notice of its intention to take any such
action, (x) take any action referred to in the preceding clauses (i), (iii) and
(iv) above only after the Board (after having consulted with its financial
advisors) concludes in good faith that any proposed Alternative Transaction
referred to in such clauses offers terms more favorable to the Company and its
stockholders from a financial point of view than the Investment (including
arrangements under the Commercial Agreements), taking into account (A) the terms
and conditions of the proposed Alternative Transaction and this Agreement
(including the other Transaction Documents and the Commercial Agreements),
respectively, (B) all other legal, financial, regulatory and other aspects of
such proposed Alternative Transaction and the Investment (including arrangements
under the Commercial Agreements), (C) the identity of the person proposing such
Alternative Transaction, (D) the Board's determination of whether such proposed
Alternative Transaction is reasonably capable of being completed and (E) whether
financing for such proposed Alternative Transaction, to the extent required, as
reasonably determined by the Board of Directors, will be available (an

                                      -21-
<PAGE>

Alternative Transaction meeting the forgoing criteria on its most recently
amended or modified terms, if amended or modified, a "Superior Proposal"), and
only if in the good faith opinion of the Board (based upon an opinion of the
Company's outside counsel) to do so is required in the exercise of the
directors' fiduciary duties and (y) furnish to the person making such Superior
Proposal any information referred to in the preceding clause (i) only if both
(A) the Company then promptly furnishes such information to the Purchasers, or
shall have previously furnished such information to the Purchasers, and (B) such
information shall be so furnished to such person pursuant to a confidentiality
agreement no less favorable to the Company then the terms of the Confidentiality
Agreement referred to in Section 4.6 and (z) shall take any action referred to
in the preceding clauses (i), (ii) and (iii) only if the Board of Directors of
the Company shall promptly thereafter, by written notice delivered to the
Purchasers, inform the Purchasers of its intention to take such action.  The
Company will promptly notify the Purchasers if any person makes any proposal,
offer, inquiry, or contact with respect to any of the foregoing.  The Company
shall cease and cause to be terminated any existing activities, discussions or
negotiations with all persons (other than the Purchasers or any affiliate of, or
any person acting in concert with, the Purchasers) conducted on or before the
date of this Agreement with respect to any Alternative Transaction.  The Company
shall inform the persons referred to in the first sentence of this Section 4.4
of the obligations undertaken by it in this Section 4.4.

     Section 4.5.  Access to Information.  Upon reasonable notice and subject to
restrictions contained in confidentiality agreements to which such party is
subject (from which such party shall use reasonable efforts to be released), the
Company shall (and shall cause each of its subsidiaries to) afford to the
officers, employees, accountants, counsel and other representatives of the
Purchasers, reasonable access, during the period from the date hereof until the
Closing Date, to all of its properties, books, contracts, commitments and
records and, during such period, the Company shall (and shall cause each of its
subsidiaries to) furnish promptly to the Purchasers and the officers, employees,
accountants, counsel and other representatives of the Purchasers, all
information concerning its business, properties and personnel as the Purchasers
may reasonably request, and shall make available to the Purchasers the
appropriate individuals (including attorneys, accountants and other
professionals) for discussion of the Company's business, properties and
personnel as the Purchasers may reasonably request.  Each party shall keep such
information confidential in accordance with the terms of Section 4.6 hereof.

     Section 4.6.  Confidentiality. It is understood by each of the Purchasers
that the information, documents and instruments delivered to such Purchaser
directly or indirectly by the Company or its agents and the information,
documents and instruments delivered to the Company by the Purchasers or their
respective agents are of a confidential and proprietary nature (the
"confidential information").  Each of the parties hereto agrees that both prior
and subsequent to the Closing it will maintain the confidentiality of all such
confidential information delivered to it by each of the other parties hereto or
their agents in connection with the negotiation of this Agreement or in
compliance with the terms, conditions and covenants

                                      -22-
<PAGE>

hereof and will only disclose such confidential information to its duly
authorized officers, partners, directors, representatives and agents. The term
"confidential information" does not include any information that (i) at the time
of disclosure or thereafter is generally available to and known by the public
(other than as a result of its disclosure directly or indirectly by a Purchaser
or one of its agents), (ii) was available to such Purchaser on a non-
confidential basis from a source other than the Company or its advisors,
provided that such source is not and was not bound by a confidentiality
agreement regarding the Company, or (iii) has been independently acquired or
developed by such Purchaser without violation of any obligations under this
section. Each of the parties hereto further agrees that if the transactions
contemplated hereby are not consummated, it will return all such documents and
instruments and all copies thereof in its possession to the other party to this
Agreement. Each of the parties hereto recognizes that any breach of this Section
4.6 would result in irreparable harm to the other parties to this Agreement and
their affiliates and that therefore either the Company or the Purchasers, as the
case may be, shall be entitled to seek an injunction to prohibit any such breach
or anticipated breach, without the necessity of posting a bond, cash or
otherwise, in addition to all of their other legal and equitable remedies.
Nothing in this Section 4.6, however, shall prohibit the use of such
confidential information as in the opinion of the Company's counsel or any
Purchaser's counsel are required by law or governmental regulations or judicial
process; provided, however, that no such disclosure shall be made without
reasonable notice to the party that is the source of such confidential
information.

     Section 4.7.  Consents; Approvals.  The Company shall use commercially
reasonable efforts to obtain all consents, waivers, approvals, authorizations or
orders required in connection with the execution of this Agreement and the
consummation of the transactions contemplated hereby (including, without
limitation, (i) consents under the agreements set forth on Section 4.7 of the
Company's Disclosure Schedule and (ii) all United States and foreign
governmental and regulatory rulings and approvals), and the Company shall make
all filings (including, without limitation, all filings with United States and
foreign governmental or regulatory agencies) required in connection with the
authorization, execution and delivery of this Agreement by the Company and the
consummation by it of the transactions contemplated hereby, in each case as
promptly as practicable.  The Company and the Purchasers shall furnish promptly
all information required to be included in the Proxy Statement or for any
application or other filing to be made pursuant to the rules and regulations of
any United States or foreign governmental body in connection with the
transactions contemplated by this Agreement.  The Company also shall use
commercially reasonable efforts to obtain all necessary permits and approvals
required under applicable Blue Sky Laws to carry out the transactions
contemplated hereby and shall furnish all information as may be reasonably
requested in connection with any such action.  Nothing in this Section 4.6 or
any other provision of any Transaction Document shall require any Purchaser to
sell or otherwise dispose of any substantial amount of the assets of any of the
Purchasers and their respective subsidiaries, whether as a condition to
obtaining any consent, waiver, approval, authorization or order from a
Governmental Body or any other person or for any other reason.

                                      -23-
<PAGE>

     Section 4.8.  Public Announcements.  The Purchasers and the Company shall
consult with each other before issuing any press release or public statement or
making any filing with respect to the Stock Purchase or this Agreement and shall
not issue any such press release or make any such public statement or filing
without the prior consent of the other party, which consent shall not be
unreasonably withheld; provided, however, that a party may, without the prior
consent of the other party, issue such press release or make such public
statement or filing as may upon the advice of counsel be required by law or the
rules and regulations of the Nasdaq National Market ("NASDAQ"), if it has used
all reasonable efforts to consult with the other party prior thereto, and shall
promptly notify the other parties hereto thereof.

     Section 4.9.  Listing.  The Company shall use its best efforts to (i)
continue the quotation of its Common Stock on the Nasdaq during the term of this
Agreement and for so long as any of the Shares are outstanding and (ii) to file
all forms, accompanied by the appropriate fee, to include the shares of Common
Stock into which the Shares are convertible and for which the Warrants may be
exercisable, in the Common Stock listed for quotation.

     Section 4.10.  Board of Directors.  The Certificate of Designation provides
for up to two directors to be elected by class vote of the holders of Preferred
Stock.  For so long as the Purchasers or their permitted assignees have a right
under the Certificate of Designation to elect one or more directors, this
Section 4.10 shall govern the mechanism of their election, and is to operate in
conformity with, rather than in addition to, the Certificate of Designation.  At
such time as such provisions in the Certificate of Designation no longer apply,
the provisions of this Section 4.10 shall determine the Company's obligations
with regard to the nomination of directors representing the Purchasers.

          (a)  On the day after the Closing Date the Company shall take all
     necessary action to elect two nominees of the Purchasers to the Company's
     Board as provided in the Certificate of Designation.  No later than the
     Closing Date, each of U.S. Telesource, Inc. ("TELESOURCE") and Oak shall
     provide to the Company one nominee's name (the "TELESOURCE NOMINEE" and the
     "OAK NOMINEE", respectively, and together the "NOMINEES") as soon as
     practicable after the Closing.  The Telesource Nominee shall be elected to
     the class of directors whose current term expires in 2000 (the "CLASS II")
     and the Oak Nominee shall be elected to the class of directors whose
     current term expires in 2001 ("CLASS I").

          (b)  The Company agrees to take the following action regarding ongoing
     representation on the Board of Directors:

               (i)  Until the date that Telesource and its affiliates no longer
     own a number of shares of Preferred Stock and Common Stock greater than or
     equal to one-quarter of the number of shares of Preferred Stock issued to
     Telesource on the Closing Date (or Common Stock into which such Preferred
     Stock was convertible), Telesource will have the right to nominate the
     Telesource Nominee

                                      -24-
<PAGE>

          for a Class II director upon each regular election of such class of
          directors. Such number of shares shall be appropriately adjusted to
          reflect stock splits, dividends, recapitalizations and the like.

               (ii)  Until the date that Oak, MeriTech, Accel, Brentwood,
          Worldview, Bessemer Venture Partners IV, L.P. and Adams Capital
          Management, L.P. together no longer own a number of shares of
          Preferred Stock and Common Stock greater than or equal to one-quarter
          of the number of shares of Preferred Stock issued to all of them on
          the Closing Date (or Common Stock into which such Preferred Stock was
          convertible), Oak will have the right to nominate the Oak Nominee for
          a Class I director upon each regular election of such class of
          directors.  Such number of shares shall be appropriately adjusted to
          reflect stock splits, dividends, recapitalizations and the like.

               (iii)  In the event that the right of the holders of Preferred
          Stock to elect two directors pursuant to Section 4(d) of the
          Certificate of Designation shall terminate, the Purchasers shall
          designate whichever Nominee is in the class of directors to be elected
          at the next meeting of stockholders, or if neither Nominee is in such
          class, then in the next-subsequent class, as the director as to whom a
          class vote of the Preferred Stock is required.  The other Nominee
          shall then continue in accordance with the Company's by-laws, and the
          provisions of this Section 4.10 shall control the re-election or
          replacement of such Nominee.  In the event that holders of Preferred
          Stock have no right to elect any directors pursuant to the Certificate
          of Designation, this Section 4.10 shall govern the nomination of the
          Nominees.

               (iv)  Each of Telesource and Oak shall notify the Company in
          writing of the identity of its Nominee, as applicable, for election to
          the Board at the same time shareholder proposals are due as set forth
          in the Company's proxy statement filed the preceding year for an
          election year when either of them has such a right, which notice shall
          be conclusive evidence of the consent of such nominee to serve as a
          director of the Company.  In the event either Telesource or Oak fails
          to provide such notice, the then-serving Telesource Nominee or Oak
          Nominee, as applicable, for the class of directors being elected shall
          be deemed to be renominated.  The notice shall include all information
          with respect to such nominee as is required to be included in a proxy
          statement soliciting proxies for the election of directors pursuant to
          Regulation 14A of the Exchange Act.  In the event of any vacancy
          arising by reason of the resignation, death, removal or inability to
          serve of the Telesource Nominee or the Oak Nominee, Telesource or Oak,
          as applicable, shall notify the Company of its choice to fill such
          vacancy, and the Company shall take all actions necessary to elect
          such person to serve until the next meeting of the stockholders for
          the election of directors of the Company.

                                      -25-
<PAGE>

               (v)  In any year when either Telesource or Oak has such a right,
          the Company shall cause the Telesource Nominee or the Oak Nominee, as
          applicable, nominated by Telesource or Oak for election to the Board
          to be included in the slate of nominees presented by the Board to the
          stockholders of the Company for election as directors at the relevant
          annual meeting of the stockholders, and shall use its reasonable
          efforts to cause the election of such Telesource Nominee or Oak
          Nominee, as applicable, including soliciting proxies in favor of the
          election of such nominee.  The Company shall not solicit proxies of
          the stockholders of the Company to vote against any such nominee or
          for the approval of any stockholder or other proposals that are
          inconsistent with the rights afforded the Purchasers pursuant to this
          Section 4.10.

               (vi)  For so long as the Purchasers' have such a right, the
          Company shall use its best efforts at all times to take such action as
          is necessary to ensure that the Board nominates and presents to
          stockholders the proposed election of the Telesource Nominee or the
          Oak Nominee, as applicable.  As a condition precedent to the inclusion
          of any proposed nominee to be presented to stockholders by the Board
          pursuant to this Section 4.10, the Board or, if established, the
          nominating committee of the Board, may review the information provided
          pursuant to this Section 4.10 to evaluate in good faith such nominee's
          character and fitness to serve as a director.  If the Board or the
          nominating committee, as the case may be, determines in good faith
          that any such nominee lacks the character or fitness to serve as a
          director based on applicable legal and reasonable commercial
          standards, the Board or the nominating committee, as the case may be,
          shall inform Telesource or Oak, as applicable, of such determination,
          and Telesource or Oak, as applicable, shall then have the right to
          propose an alternative nominee.

               (vii)  For so long as the Purchasers have the right to nominate
          nominees for election to the Board as set forth in this Section 4.10,
          any committee of the Board shall include at least one of the Purchaser
          Nominees (except for any committee on which neither of them is
          eligible to serve under the Nasdaq listing rules).

     Section 4.11.   Certificate of Designation.  The Company shall, prior to
the Closing, cause to be filed with the Secretary of State of Delaware, a
certificate of designation in the form attached hereto as Exhibit C,
                                                          ---------
establishing the terms and conditions of the Preferred Stock (the "CERTIFICATE
OF DESIGNATION").

     Section 4.12.  Increase of Option Pool.  The Company shall submit for
stockholder approval at the Stockholders Meeting a proposal to approve a 4
million share increase in the number of shares of Common Stock issuable pursuant
to the Company's Restated Equity Incentive Plan.

                                      -26-
<PAGE>

     Section 4.13.  Use of Proceeds.  The proceeds received by the Company from
the issuance of the Notes will be used in accordance with the provisions of
Section 4.14 hereof, and the proceeds from the sale of the Shares shall be used
by the Company in the furtherance of the business plan approved by the Board of
Directors on May   , 1999, as such plan may be amended by the Board following
the Closing (the "BUSINESS STRATEGY PLAN").

     Section 4.14.  Interim Operations.  The Company covenants and agrees that
during the period from the date of this Agreement and until the earlier of the
termination of this Agreement pursuant to Section 6.1 or the Closing, unless the
Company and Two-Thirds in Interest of the Purchasers otherwise prior thereto
agree, each of the Company and its subsidiaries shall conduct its business in
the ordinary course in the three markets, two pilot programs and facility update
programs listed on Schedule 4.14 or in furtherance of the Business Plan as it
relates to the period prior to commencement of revenue operations thereunder and
shall not, except either as contemplated by this Agreement or in furtherance of
the Business Strategy Plan, do any of the following: (i) except for any payments
required to obtain consents required to be obtained pursuant to this Agreement,
incur, assume or guarantee any liability or pay, discharge or satisfy any
liability other than in the ordinary course of business; (ii) create or assume
any Lien other than in the ordinary course of business; (iii) waive, release,
cancel, settle or compromise any debt, claim or right of any material value;
(iv) transfer or waive any material right under any material lease, license or
agreement or any material Company Intellectual Property; (v) pay or agree to pay
any bonus, extra compensation, pension, continuation, severance or termination
pay, or otherwise increase the wage, salary, pension, continuation, severance or
termination pay or other compensation (of any nature) to its directors, officers
or employees, except as required by law, other than for normal compensation
increases and promotions for employees (other than for executive officers) in
the ordinary course of business, as provided in the Company's plans and
agreements identified in the Disclosure Schedule or as are not material in the
aggregate; (vi) make any loan to or enter into any transaction with any of its
directors, officers or employees (other than pursuant to any such person's
status as an employee of the Company) giving rise to any claim or right of, by,
or against any person in an amount or having a value in excess of $10,000
individually, except travel and entertainment advances in the ordinary course of
business and consistent with Company policies; (vii)  enter into, amend or
terminate any material agreement or transaction; (viii) make any contribution to
any Employee Plan, other than regularly scheduled contributions and
contributions required to maintain the funding levels of any Employee Plan, or
make or incur any commitment to establish or increase the obligation of the
Company or a subsidiary to any Employee Plan; (ix) create, assume or incur any
indebtedness for money borrowed, or guaranties thereof, except for trade
accounts payable incurred in the ordinary course of business or borrowings under
the Company's working capital line of credit facility as in effect on the date
hereof, or issue any debt securities, warrants or other rights to acquire any
debt securities of the Company or any of its subsidiaries; (x) issue, deliver or
sell, or authorize or propose the issuance, delivery or sale of, any shares of
capital stock of any class, any securities convertible into or exercisable for,
or

                                      -27-
<PAGE>

any rights, warrants or options to acquire, any such shares, of the Company
or any of its subsidiaries except for (A) the grant of options to acquire not
more than 100,000 shares in the aggregate to new employees or promoted employees
(other than executive officers) in the ordinary course of business pursuant to
its equity incentive plans or automatic grants of options and deferred stock
pursuant to the director's equity incentive plan, in each case as in effect on
the date hereof or (B) stock issued upon exercise of outstanding options and
warrants; (xi) amend or modify any provision of the Business Strategy Plan;
(xii) amend or modify any provision of its charter, by-laws or other governing
documents, except for the proposed amendments to the Company's by-laws set forth
on Schedule 2.8; (xiii) make any capital expenditures for capital improvements
or commitments therefor except as committed on the date hereof and in any event
limited in the aggregate to $6,200,000; (xiv) expand the Company's network or
operations beyond its three existing markets, two pilot programs and facility
update program or expand its marketing beyond its three existing markets; (xv)
sell, assign or dispose of any of the FCC Licenses listed on Exhibit 2.19 or any
right thereunder; or (xvi) agree to or make any commitment to take any actions
prohibited by this Section 4.14.

     Section 4.15.  Restricted Securities.  Each Purchaser understands that the
Shares purchased by it and the Common Stock issued upon conversion thereof
(collectively the "SECURITIES") may not be sold, transferred, or otherwise
disposed of without registration under the Securities Act, or an exemption
therefrom, and that in the absence of an effective registration statement
covering such Securities or an available exemption from registration under the
Securities Act, such Securities must be held indefinitely.  Each Purchaser
agrees not to make any disposition of all or any portion of the Securities
unless and until:

          (1)  There is then in effect a registration statement under the
     Securities Act covering such proposed disposition and such disposition is
     made in accordance with such registration statement and all applicable Blue
     Sky Laws; or

          (2)  (A) Such Purchaser shall have notified the Company of the
     proposed disposition and (B) such Purchaser shall have furnished the
     Company with an opinion from counsel, reasonably satisfactory to the
     Company, that such disposition will not require registration of such shares
     under the Securities Act and any applicable Blue Sky Laws in connection
     with such disposition.

     Notwithstanding the provisions of paragraphs (1) and (2) above, no such
registration statement or opinion of counsel shall be necessary for a transfer
by any Purchaser with or without consideration to a partner, member, subsidiary,
shareholder or affiliate of such Purchaser, including, without limitation, any
partner of such Purchaser and any venture capital fund now or hereafter existing
which is controlled by or is under common control with one or more general
partners of such Purchaser, provided such transferee becomes a party to this
Agreement and specifically agrees to be bound by the agreement in this Section
4.15.

                                      -28-
<PAGE>

     Section 4.16.  Preemptive Rights.

          (a)  Subject to the provisions of Section 4.16 (c), in the event that
     following the Closing, the Company proposes to raise additional capital
     through the issuance of Common Stock (or securities convertible into or
     exercisable or exchangeable for Common Stock) other than an issuance of
     Excluded Securities ("New Securities"), each Purchaser shall have the right
     to purchase equity of such type and on substantially the same economic
     terms, including purchasing other securities issued by the Company, as the
     Company issues or sells, such that the Purchaser shall have the opportunity
     to maintain its then fully-diluted equity ownership percentage in the
     Company, subject to and in accordance with the provisions of Sections 4.16
     (b).  The then fully-diluted equity ownership percentage of each Purchaser
     (such Purchaser's "Purchaser Percentage") shall be the quotient of (i) the
     sum of the number of shares of Common Stock then held by such  Purchaser
     plus the number of shares of Common Stock issuable upon conversion of any
     Shares then held by such Purchaser plus the number of shares of Common
     Stock then held by such Purchaser issued to such Purchaser as New
     Securities, or issuable upon exercise or conversion of New Securities
     issued to such Purchaser then held by such Purchaser divided by (ii) the
     total number of shares of Common Stock outstanding plus the number of
     shares of Common Stock issuable upon conversion of any Shares then
     outstanding plus the number of shares of Common Stork issuable upon the
     exercise or conversion of any security exercisable or exchangeable for or
     convertible into Common Stock.

          (b)  The rights of the Purchaser under Section 4.16(a) shall be
     effected in accordance with the following:

               (i)   The Company shall give written notice to each Purchaser as
          soon as practicable of its intention to issue New Securities;

               (ii)  The Company shall supply each Purchaser with copies of all
          relevant documents relating to such issuance as are provided to
          potential purchasers in such an issuance at substantially the same
          time as provided to such potential purchasers;

               (iii) The Company shall inform potential purchasers of such New
          Securities of the rights of the Purchasers under this Section 4.16 to
          subscribe for a portion of such issuance.  Each Purchaser shall make a
          good faith effort to provide the Company with an estimate of its
          intent to exercise its rights under this Section 4.16 before the
          Company distributes final documents to potential purchasers of the New
          Securities;

               (iv)  The Company shall provide each Purchaser with copies of all
          of the executed agreements relating to each such issuance; and

                                      -29-
<PAGE>

               (v)   Within ten days following each Purchaser's receipt of
          agreements pursuant to (iv) above, such Purchaser shall provide
          written notice to the Company (the "Commitment Notice") as to whether
          such Purchaser exercises its rights under this Section 4.16 with
          respect to such issuance, and, if so, the number of securities to be
          purchased by such Purchaser.  If any Purchaser fails to provide the
          Commitment Notice within the stated ten day period, such Purchaser
          will be deemed to have waived its rights under Section 4.16 of this
          Agreement with respect to such issuance.  The Commitment Notice of
          each Purchaser shall constitute a binding and enforceable commitment
          by such Purchaser subject to any closing conditions contained in the
          agreements referred to in clause (iv) above, to purchase the lower of
          (a) number of securities specified in such Purchaser's Commitment
          Notice and (b) such Purchaser's Purchaser Percentage of the number of
          securities sold in such issuance at the price and on all of the other
          terms and conditions of such issuance (including, if appropriate,
          signing the same documents as signed by other purchasers) either (i)
          if such issuance has not yet been consummated, at the same time as
          such securities are sold or (ii) if such issuance has been
          consummated, within twenty days of the date of the receipt by
          Purchaser of the agreements pursuant to (iv) above.

          (c)  The rights of each Purchaser under this Section 4.16 shall
     terminate on the first date on which such Purchaser no longer holds Common
     Stock or Preferred Stock representing at least 25% of the Common Stock into
     which the Shares purchased by such Purchaser hereunder are ultimately
     convertible (determined on an as if fully converted basis).

          (d)  "Excluded Securities" shall mean (i) any securities issued
     pursuant to any Company equity incentive plan or benefit plan or, (ii) any
     securities issued in connection with any stock split, stock dividend or
     other similar event, (iii) any securities issued pursuant to the Rights
     Plan, (iv) any security issued upon exercise, conversion or exchange of any
     New Security, Excluded Security or security outstanding on the date hereof,
     (v) any issuance of securities in a private placement in an offering
     customarily known as a "144A Offering" in which either the investors have
     the right to exchange any purchased securities for securities registered
     under the Securities Act or a similar right to cause the registration of or
     otherwise freely trade such securities, (vi) any issuance of securities
     issued to financial institutions or other lenders in connection with any
     offering of debt securities or borrowing by the Company, (vii) any issuance
     of securities in a public offering registered under the Securities Act,
     (viii) any issuance of securities as consideration for the acquisition of
     assets or any ownership interest in any Person, (ix) any conversion of the
     Preferred Stock and (x) any other securities deemed to be Excluded
     Securities by the Company and Two-Thirds in Interest of the Purchasers.

                                      -30-
<PAGE>

     Section 4.17.  Amendment of Rights Agreement.   Prior to the Closing, the
Company shall have amended the Rights Agreement in substantially the form
presented to the Purchasers on the date hereof.

     Section 4.18.  FCC Approvals. The Company covenants and agrees that within
ninety (90) days following the Closing, the Company shall file and use
commercially reasonable efforts to obtain a grant of substantive transfer of
control applications with the FCC detailing the new ownership of the Company to
avoid regulatory delays for future conversion of convertible instruments.


                                   ARTICLE V

                        CONDITIONS TO THE STOCK PURCHASE

     Section 5.1.  Conditions to Obligation of Each Party to Effect the Stock
Purchase.  The respective obligations of each party to effect the Stock Purchase
shall be subject to the satisfaction at or prior to the Closing Date of the
following conditions:

          (a)  Stockholder Approval.  The Stock Purchase shall have been
     approved by the holders of at least a majority of the votes cast at the
     Special Meeting, provided that a quorum shall be present;

          (b)  HSR Act.  All waiting periods applicable to the consummation of
     the Stock Purchase under the HSR Act shall have expired or been terminated;
     and

          (c)  No Injunctions or Restraints; Illegality.  No temporary
     restraining order, preliminary or permanent injunction or other order
     issued by any court of competent jurisdiction or other legal restraint or
     prohibition preventing the consummation of the Stock Purchase shall be in
     effect, nor shall any proceeding brought by any administrative agency or
     commission or other governmental authority or instrumentality, domestic or
     foreign, seeking any of the foregoing be pending; and there shall not be
     any action taken, or any statute, rule, regulation or order enacted,
     entered, enforced or deemed applicable to the Stock Purchase, which makes
     the consummation of the Stock Purchase illegal.

     Section 5.2.  Additional Conditions to Obligations of the Purchasers.  The
obligations of the Purchasers to effect the Stock Purchase are also subject to
the following conditions:

          (a)  Representations and Warranties.  The representations and
     warranties of the Company contained herein shall be true and correct (as if
     any materiality qualifications were not contained therein) at and as of the
     Closing Date as if made at and as of such date, except for (i) changes
     contemplated by this Agreement, (ii) those representations

                                      -31-
<PAGE>

     and warranties which address matters only as of a particular date (which
     shall have been true and correct as of such date) and (iii) where the
     failure to be true and correct does not constitute a Material Adverse
     Effect, with the same force and effect as if made at and as of the Closing
     Date and the Purchasers shall have received a certificate to such effect
     signed on behalf of the Company by the Chairman, President or the Chief
     Financial Officer of the Company;

          (b)  Agreements and Covenants.  The Company shall have performed or
     complied in all material respects with all agreements and covenants
     required by this Agreement to be performed or complied with by it at or
     prior to the Closing Date, and the Purchasers shall have received a
     certificate to such effect signed on behalf of the Company by the Chairman,
     President or Chief Financial Officer of the Company;

          (c)  Consents Obtained.  All consents, waivers, approvals,
     authorizations or orders required to be obtained, and all filings required
     to be made, by the Company for the due authorization, execution and
     delivery of this Agreement and the consummation by it of the transactions
     contemplated hereby shall have been obtained and made by the Company,
     except where the failure to receive such consents, waivers, approvals,
     authorizations or orders could not reasonably be expected to (i) have a
     Material Adverse Effect on the Company, or (ii) significantly delay or
     prevent the consummation of the Stock Purchase;

          (d)  Amendment of the Indenture.  The Company shall have obtained the
     consent of holders of not less than two-thirds in principal amount of the
     Company's senior notes issued pursuant to the Indenture dated as of
     February 6, 1997 between the Company and The Bank of New York, as Trustee
     (the "INDENTURE") to the valid and effective amendment of the Indenture
     pursuant to an instrument in substantially the form provided to the
     Purchasers on the date hereof, unless otherwise agreed to by the Company
     and Two-Thirds in Interest of the Purchasers;

          (e)  Opinion of Counsel.  The Purchasers shall have received a written
     opinion from Ropes & Gray, in form and substance reasonably satisfactory to
     the Purchasers, substantially in the form of Exhibit D hereto;
                                                  ---------

          (f)  FCC Opinion.  The Purchasers shall have received a written
     opinion from Wiley, Rein & Fielding, the Company's FCC counsel, in form and
     substance reasonably satisfactory to the Purchasers, substantially in the
     form of Exhibit E hereto;
             ---------

          (g)  Blue Sky Laws.  The Company shall have received all permits and
     other authorizations necessary under the Blue Sky Laws to issue the Shares
     and the Common Stock issuable upon conversion thereof pursuant to the Stock
     Purchase;

                                      -32-
<PAGE>

          (h)  Nasdaq Listing. The shares of Common Stock issuable upon
     conversion of the Shares shall have been listed or approved for listing
     upon notice of issuance on Nasdaq;

          (i)  Registration Rights Agreement.  The Company shall have executed
     and delivered to the Purchasers the Registration Rights Agreement in
     substantially the form of Exhibit F hereto;
                               ---------

          (j)  Delivery of Shares.  The Company shall have delivered the Shares
     to be delivered pursuant to Section 1.2 hereof against the payment of the
     Purchase Price;

          (k) Resignation of Directors.  Two current members of the Board shall
     have resigned immediately prior to Closing and there shall be one Class I
     vacancy and one Class II vacancy on the Board, to be filled in accordance
     with Section 4.10;

          (l) Commercial Agreements. The Company and Qwest Communications
     Corporation ("Qwest") shall have executed and delivered (i) the Qwest
     Communications Corporation Private Line Services Agreement between the
     Company and Qwest in the form of Exhibit G, (ii) the Collocation License
     Agreement between the Company and Qwest in the form of Exhibit H, and (iii)
     the Coordinated Marketing Agreement between the Company and Qwest in the
     form of Exhibit I (collectively, the "COMMERCIAL AGREEMENTS"); and

          (m) Corporate Proceedings. The Secretary or an Assistant Secretary of
     the Company shall have delivered to the Purchasers a certificate, dated as
     of the Closing, certifying to the Company's charter and bylaws, the
     incumbency and specimen signatures of its certain officers and the
     corporate action taken by the Company in connection with the Transaction
     Documents.

     Section 5.3.  Additional Conditions to Obligation of the Company.  The
obligation of the Company to effect the Stock Purchase is also subject to the
following conditions:

          (a)  Representations and Warranties.  The representations and
     warranties of the Purchasers contained in this Agreement shall be true and
     correct in all material respects on and as of the Closing Date, except for
     (i) changes contemplated by this Agreement and (ii) those representations
     and warranties which address matters only as of a particular date (which
     shall have been true and correct as of such date), with the same force and
     effect as if made on and as of the Closing Date, and the Company shall have
     received a certificate to such effect signed by the President or Chief
     Financial Officer of each Purchaser or of the general partner of each of
     the Purchasers, as applicable;

          (b)  Agreements and Covenants.  The Purchasers shall have performed or
     complied in all material respects with all agreements and covenants
     required by this

                                      -33-
<PAGE>

     Agreement to be performed or complied with by them on or prior to the
     Closing Date, and the Company shall have received a certificate to such
     effect signed by the President or Chief Financial Officer of the general
     partner or manager of each of the Purchasers;

          (c)  Consents Obtained.  All consents, waivers, approvals,
     authorizations or orders required to be obtained, and all filings required
     to be made, by the Company for the due authorization, execution and
     delivery of this Agreement and the consummation by it of the transactions
     contemplated hereby shall have been obtained and made by the Company,
     except where the failure to receive such consents, waivers, approvals,
     authorizations or orders could not reasonably be expected to (i) have a
     Material Adverse Effect on the Company, or (ii) significantly delay or
     prevent the consummation of the Stock Purchase; provided, that the Company
                                                     --------
     will be deemed to have waived this condition if the failure to obtain such
     consents and waivers is due to the Company's material breach of its
     obligations under this Agreement;

          (d)  Payment of Purchase Price.  Each of the Purchasers shall have
     delivered full payment of the Purchase Price for the Shares to be purchased
     by such Purchaser at the Closing as set forth on Schedule I hereof.

          (e)  Standstill Agreement.  The Standstill Agreement in the form of
     Exhibit K shall have been duly executed and delivered by each of the
     Purchasers party thereto and shall be in full force and effect and shall
     not have been breached in any material respect by any of such Purchasers.

          (f)  Commercial Agreements.  The Company and Qwest shall have executed
     and delivered each of the Commercial Agreements.



                                  ARTICLE VI

                                  TERMINATION

     Section 6.1.  Termination.  This Agreement may be terminated at any time
prior to the Closing Date, notwithstanding approval thereof by the stockholders
of the Company:

          (a)  by mutual written consent of the Company and Two-Thirds in
     Interest of the Purchasers; or

          (b)  by either Two-Thirds in Interest of the Purchasers or the Company
     if a court of competent jurisdiction or governmental, regulatory or
     administrative agency or commission shall have issued a nonappealable final
     order, decree or ruling or taken any

                                      -34-
<PAGE>

     other action having the effect of permanently restraining, enjoining or
     otherwise prohibiting the Stock Purchase; or

          (c)  by Two-Thirds in Interest of the Purchasers, if the requisite
     vote of the stockholders of the Company shall not have been obtained by the
     Final Maturity Date (provided that the right to terminate this Agreement
     under this Section 6.1(c) shall not be available to the Purchasers to the
     extent that their failure to provide information required to be included in
     the proxy statement has been the cause of or resulted in the failure to
     obtain the requisite stockholder vote on or before such date); or

          (d)  by Two-Thirds in Interest of the Purchasers or the Company, (i)
     if any representation or warranty of the Company or the Purchasers,
     respectively, set forth in this Agreement shall be untrue when made, or
     (ii) upon a breach of any covenant or agreement on the part of the Company
     or the Purchasers set forth in this Agreement, such that the conditions set
     forth in Sections 5.2(a), 5.2(b), 5.3(a) or 5.3(b), as the case may be,
     would not be satisfied, provided that if any of the circumstances set forth
     in clause (i) or (ii) is curable within forty-five calendar days after
     notice of the Company's or the Purchasers', as the case may be, intent to
     terminate this Agreement, through the exercise of reasonable efforts and
     for so long as the Company or the Purchasers, as the case may be, continues
     to exercise such reasonable efforts, neither the Purchasers nor the
     Company, as the case may be, may terminate this Agreement under this
     Section 6.1(d) until after the last day of such period; or

          (e)  by Two-Thirds in Interest of the Purchasers, if the Company or
     the Board shall have (A) authorized or recommended (or publicly announced
     its intention to authorize or recommend) an agreement with respect to an
     Alternative Transaction with respect to any of the Company and its
     subsidiaries, (B) recommended that the stockholders of the Company accept
     or approve any such Alternative Transaction or (C) modified or amended the
     approval by the Board of the Stock Purchase, including any modification or
     rescission of the adoption of resolutions covering the matters addressed in
     Section 2.4(b) and Section 4.17, in any respect materially adverse to the
     Purchasers or withdrawn such Board approval or authorized or recommended
     opposing the transaction; provided that (x) a communication of the Company
                               --------
     to the Purchasers that advises that the Company has received a proposal
     with respect to an Alternative Transaction and that takes no position with
     respect to such proposal shall not be deemed to be a modification,
     amendment or withdrawal of the Board's approval of the Stock Purchase and
     (y) a "stop-look-and-listen" communication of the nature contemplated in
     Rule 14d-9(e) under the Exchange Act with respect to an unsolicited tender
     offer or exchange offer that, if concluded in accordance with the terms
     thereof, would constitute or result in an Alternative Transaction with
     respect to any of the Company and its subsidiaries (other than the Stock
     Purchase), without more, shall not be deemed to be a modification,
     amendment or withdrawal of the Board's approval of the Stock Purchase if,
     within the time period contemplated by Rule 14e-2 under the Exchange Act,
     the

                                      -35-
<PAGE>

     Board shall publicly confirm its approval of the Stock Purchase and
     recommend against the acceptance of such tender offer or exchange offer by
     the stockholders of the Company; or

          (f)  by the Company, if (A) the Board of Directors of the Company
     shall have determined that an unsolicited, bona fide proposal made by any
     person with respect to an Alternative Transaction with respect to the
     Company is a Superior Proposal, (B) the Board of Directors of the Company
     shall have complied in all material respects with Section 4.4 with respect
     to actions taken or proposed to be taken by the Company or the Board of
     Directors of the Company with respect to such Superior Proposal, (C) the
     Company shall have notified the Purchasers in writing, not less than two
     business days in advance of taking such action, of its election to
     terminate the obligations of the parties pursuant to this Section 6.1(f)
     for the purpose of recommending that the stockholders of the Company accept
     or approve such Superior Proposal or authorizing, recommending or proposing
     an agreement with respect to such Superior Proposal, (D) the Company and
     its advisors and representatives shall have discussed with the Purchasers
     during such two day period the modifications to the terms of this
     Agreement, the Transaction Documents and the Commercial Agreements that
     would permit the Company to conclude the Investment in lieu of concluding
     such Superior Proposal, and (E) at the end of such two business day period
     the Board of Directors of the Company shall have determined that such
     Superior Proposal continues to constitute a Superior Proposal; or

          (g)  by the Company or Two-Thirds in Interest of the Purchasers, if
     the Closing has not occurred by the end of the second business day
     following the Final Maturity Date (provided that the right to terminate
     this Agreement under this Section 6.1(g) shall not be available to any
     party whose material breach of any representation or warranty or failure to
     fulfill any obligation under this Agreement has been the cause of or
     resulted in the failure of the Closing to occur on or before such date).

     Section 6.2.  Effect of Termination.  In the event of the termination of
this Agreement pursuant to Section 6.1, this Agreement shall forthwith become
void and there shall be no liability on the part of any party hereto or any of
its affiliates, directors, officers or stockholders except (i) as set forth in
Section 6.3 and Section 7.1 hereof, and (ii) nothing herein shall relieve any
party from liability for any breach hereof.

     Section 6.3.  Fees and Expenses.  All fees and expenses incurred in
connection with this Agreement and the transactions contemplated hereby shall be
paid by the party incurring such expenses, whether or not the Stock Purchase is
consummated; provided that, the Company shall pay the reasonable fees (not to
exceed $150,000) and expenses of counsel to the Purchasers incurred in
connection with the negotiation, preparation, execution and delivery of this
Agreement and any other instruments and agreements contemplated hereby, and the

                                      -36-
<PAGE>

Company shall pay all fees incurred in connection with all required filings
under the HSR Act (not to exceed $180,000).

                                  ARTICLE VII

                               GENERAL PROVISIONS

     Section 7.1.  Effectiveness of Representations, Warranties and Agreements;
Knowledge, Etc.

          (a)  Except as otherwise provided in this Section 7.1, the
     representations, warranties and agreements of each party hereto shall
     remain operative and in full force and effect regardless of any
     investigation made by or on behalf of any other party hereto, any person
     controlling any such party or any of their officers or directors, whether
     prior to or after the execution of this Agreement.  The representations,
     warranties and agreements in this Agreement and certificates delivered
     pursuant hereto shall survive the Closing Date until the date that is three
     months after the filing of the Company's Annual Report on Form 10-K for the
     period ended December 31, 1999 or upon the termination of this Agreement
     pursuant to Section 6.1, as the case may be, at which time they shall
     terminate and be of no further force or effect, except that the agreement
     set forth in Section 4.6 shall survive for two years from the Closing Date,
     the agreements contained in Sections 4.10, 4.13, 4.15, 4.16, 7.1 or 7.2
     shall last indefinitely, unless sooner terminated in accordance with their
     respective terms and the agreement set forth in Section 6.3 shall survive
     the Closing Date until paid.

          (b)  Any disclosure made with reference to one or more sections of the
     Company Disclosure Schedule shall be deemed disclosed with respect to any
     section with such Disclosure Schedule to which such disclosure reasonably
     relates.

     Section 7.2.  Restrictive Legends. Each certificate representing Shares or
Conversion Shares shall bear legends in substantially the following form:

     The securities represented by this certificate have not been registered
     under the Securities Act of 1933 or the securities laws of any state and
     may not be sold or otherwise disposed of except pursuant to an effective
     registration statement under such Act and applicable state securities laws
     or an applicable exemption to the registration requirements of such Act or
     such laws.

     The securities represented by this certificate were issued pursuant to, and
     the holder hereof is entitled to certain rights and subject to certain
     obligations contained in, a Stock Purchase Agreement dated as of June __,
     1999, a copy of which is available for inspection at the principal office
     of the issuer hereof, and will be furnished without charge to the holder of
     such securities upon written request.

                                      -37-
<PAGE>

     Each certificate representing Shares or Conversion Shares shall also bear
any other legends required by any applicable law.

     Section 7.3  Notices.  All notices and other communications given or made
pursuant hereto shall be in writing and shall be deemed to have been duly given
or made if and when delivered personally or by overnight courier to the parties
at the following addresses or sent by electronic transmission, with confirmation
received, to the telecopy numbers specified below (or at such other address or
telecopy number for a party as shall be specified by like notice):

          (a)  If to the Purchasers, to such address listed on Schedule I
     hereto,  with a copy to:

          Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP
          155 Constitution Drive
          Menlo Park, CA  94025
          Attn:  Brooks Stough, Esq.
          Telecopier No.: (650) 321-2800
          Telephone No.:  (650) 463-5370

and to:
          O'Melveny & Myers LLP
          1999 Avenue of the Stars
          Los Angeles, CA  90067-6035
          Attn:  Steven L. Grossman, Esq.
          Telecopier No.: (310) 246-6779
          Telephone No.:  (310) 553-6700


          (b)  If to the Company:

          Advanced Radio Telecom Corp.
          500 108th Avenue NE, Suite 2600
          Bellevue, WA  98004
          Attn: Thomas M. Walker, Esq., General Counsel
          Telecopier No.: (425) 990-1642 or (425) 688-0703
          Telephone No.:  (425) 990-1669

          With a copy to:

          Ropes & Gray
          One International Place
          Boston, MA  02110
          Attn: Mary E. Weber, Esq.
          Telecopier No.: (617) 951-7050
          Telephone No.:  (617) 951-7391

                                      -38-
<PAGE>

     Section 7.4.  Certain Definitions.  For purposes of this Agreement, the
term:

          (a)  "AFFILIATE" means a person that directly or indirectly, through
     one or more intermediaries, controls, is controlled by, or is under common
     control with, the first mentioned person; including, without limitation,
     any partnership or joint venture in which the first mentioned person
     (either alone, or through or together with any other subsidiary) has,
     directly or indirectly, an interest of 10% or more;

          (b)  "ALTERNATIVE TRANSACTION" means, whether concluded or intended to
     be concluded in any transaction or series of transactions, any of the
     following with respect to the Company and its subsidiaries (other than the
     transactions contemplated by this Agreement):

               (1) the acquisition from the Company or from any third persons of
               any equity securities of the Company as a result of which the
               holders of equity securities of the Company immediately before
               such transaction would own beneficially directly or indirectly
               less than 75% of the equity securities of the Company issued and
               outstanding immediately after such transaction;

               (2) the merger or consolidation of any of the Company with or
               into any person other than the Company or one of its wholly-owned
               subsidiaries as a result of which the holders of equity
               securities of the Company immediately before such transaction
               would own beneficially directly or indirectly less than 75% of
               the equity securities of the Company or the surviving entity
               issued and outstanding immediately after such transaction;

               (3) the sale of a substantial portion of the assets of the
               Company and its subsidiaries to any person or group other than
               the Company or its wholly-owned subsidiaries; or

               (4) any transaction (whether or not any of the Company or its
               subsidiaries shall be a party thereto) as a result of which a
               majority of the members of the board of directors, or similar
               officials, of the Company or such subsidiary would not be persons
               who on the day after the closing date of such transaction were
               members of the board of directors, or similar officials, or who
               were nominated for election or elected with the approval of a
               majority of the directors, or similar

                                      -39-
<PAGE>

               officials, who were directors, or similar officials, on that date
               or whose nomination or election was previously so approved.

          (c)  "CONTROL" (including the terms "controlled by" and "under common
     control with") means the possession, directly or indirectly or as trustee
     or executor, of the power to direct or cause the direction of the
     management or policies of a person, whether through the ownership of stock,
     as trustee or executor, by contract or credit arrangement or otherwise;

          (d) "GOVERNMENTAL BODY" means any agency, bureau, commission, court,
     department, official, political subdivision, tribunal or other
     instrumentality of any government, whether federal, state, county or local,
     domestic or foreign, of competent jurisdiction.

          (e)  "KNOWLEDGE" means the actual knowledge of any director or
     executive officer after reasonable investigation;

          (f)  "MATERIAL ADVERSE EFFECT" means, when used in connection with the
     Company or any of the Company's subsidiaries, as the case may be, any
     change, effect or circumstance that, individually or when taken together
     with all changes, effects or circumstances that have occurred prior to the
     date of determination of the occurrence of the Material Adverse Effect and
     with respect to which such phrase is used, (a) has been, is or could
     reasonably be expected to be materially adverse to the business, assets,
     results of operations or condition (financial or otherwise) of the Company
     and its subsidiaries, in each case taken as a whole, or (b) is or is
     reasonably likely to delay or prevent the consummation of the transactions
     contemplated hereby.

          (g)  "PERSON" means an individual, corporation, partnership,
     association, trust, unincorporated organization, other entity or group (as
     defined in Section 13(d)(3) of the Exchange Act).

          (h)  "SUBSIDIARY" or "SUBSIDIARIES" of the Company or any other person
     means any corporation, partnership, joint venture or other legal entity of
     which the Company, or such other person, as the case may be (either alone
     or through or together with any other subsidiary), owns, directly or
     indirectly, more than 50% of the stock or other equity interests the
     holders of which are generally entitled to vote for the election of the
     board of directors or other governing body of such corporation or other
     legal entity.

          (i)  "TWO-THIRDS IN INTEREST" means, prior to the Closing, Purchasers
     who have agreed to purchase more than 66-2/3% of the Shares and, on and
     after the Closing, Purchasers holding more than 66-2/3% of the Shares then
     owned by the Purchasers.

                                      -40-
<PAGE>

     Section 7.5.  Notification.  The Company and each Purchaser agrees to give
prompt notice to the other parties to this Agreement or any other Transaction
Document, as the case may be, of (1) the occurrence, or failure to occur, of any
event that would be likely to cause any representation or warranty of the party
contained herein or therein to be untrue or inaccurate in any material respect
at any time from the date of this Agreement to the Closing Date, any failure of
the party to perform or otherwise comply with, in any material respect, any
covenant, condition or agreement to be performed or complied with by it
hereunder or thereunder and (2) the receipt by the party of written or oral
notice from any Governmental Body or other person stating, or causing such party
to believe, that there is a reasonable likelihood that a consent, waiver,
approval, authorization or order required by this Agreement to be obtained from
such Governmental Body or other person will not be obtained timely or at all;
which covenant of notification shall not limit the right of any other party
hereunder or thereunder to require as a condition precedent to the performance
of its obligations hereunder or thereunder the continuing accuracy and
performance of the representations and warranties and covenants of the notifying
party made herein or therein and to receive an unqualified certificate with
respect to the same.

     Section 7.6.  Amendment.  This Agreement may be amended upon the written
consent of the Company and Two-Thirds in Interest of the Purchasers, at any time
prior to the Closing Date, and such amendment shall be binding on all of the
Purchasers.  This Agreement may not be amended except by an instrument in
writing signed by the Company and Two-Thirds in Interest of the Purchasers.

     Section 7.7.  Waiver.  At any time prior to the Closing Date, the parties
hereto, upon the written consent of the Company and Two-Thirds in Interest of
the Purchasers, may (a) extend the time for the performance of any of the
obligations or other acts, (b) waive any inaccuracies in the representations and
warranties contained herein or in any document delivered pursuant hereto, or (c)
waive compliance with any of the agreements or conditions contained herein.  Any
such waiver shall be binding on all of the Purchasers.

     Section 7.8.  Cooperation.  Each Purchaser severally and the Company agree
to take, or to cause to be taken, all such reasonable and lawful action as may
be necessary to make effective and consummate the transactions contemplated by
this Agreement.

     Section 7.9.  Headings.  The headings contained in this Agreement are for
reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.

     Section 7.10.  Severability.  If any term or other provision of this
Agreement is invalid, illegal or incapable of being enforced by any rule of law,
or public policy, all other conditions and provisions of this Agreement shall
nevertheless remain in full force and effect so long as the economic or legal
substance of the transactions contemplated hereby is not affected in any manner
adverse to any party.  Upon such determination that any term or other provision
is invalid, illegal or incapable of being enforced, the parties hereto shall
negotiate in good faith to modify this Agreement so as to effect the original
intent of the parties as closely as possible in

                                      -41-
<PAGE>

an acceptable manner to the end that the transactions contemplated hereby are
fulfilled to the fullest extent possible.

     Section 7.11.  Entire Agreement.  This Agreement constitutes the entire
agreement and supersedes all prior agreements and undertakings (other than the
Confidentiality Agreement dated as of March 1, 1999 between Oak Investment
Partners and the Company), both written and oral, among the parties, or any of
them, with respect to the subject matter hereof.

     Section 7.12.  Assignment.  This Agreement shall not be assigned by
operation of law or otherwise, except that each Purchaser may assign this
Agreement to any direct or indirect wholly-owned subsidiaries of its ultimate
parent and to any limited partners of any Purchaser and to any affiliate or
sidecar fund of any such Purchaser; provided, however, that the Purchasers'
                                    --------  -------
rights pursuant to Section 4.10 may be assigned only to direct or indirect
wholly-owned subsidiaries of any Purchaser's ultimate parent, unless the
Company's prior written consent is obtained, such consent not to be unreasonably
withheld. Such assignment shall not be valid unless as a condition to such
assignment, the person to whom this Agreement is assigned (i) delivers to the
Company a written instrument by which such person agrees to be bound by the
obligations imposed upon the Purchasers under this Agreement to the same extent
as if such person had been an original Purchaser hereunder and (ii) becomes a
Purchaser hereunder.

     Section 7.13.  Parties in Interest.  This Agreement shall be binding upon
and inure solely to the benefit of each party hereto, and nothing in this
Agreement, express or implied, is intended to or shall confer upon any other
person any right, benefit or remedy of any nature whatsoever under or by reason
of this Agreement, including, without limitation, by way of subrogation.

     Section 7.14.  Failure or Indulgence Not Waiver; Remedies Cumulative.  No
failure or delay on the part of any party hereto in the exercise of any right
hereunder shall impair such right or be construed to be a waiver of, or
acquiescence in, any breach of any representation, warranty or agreement herein,
nor shall any single or partial exercise of any such right preclude any other or
further exercise thereof or of any other right.  All rights and remedies
existing under this Agreement are cumulative to, and not exclusive of, any
rights or remedies otherwise available.

     Section 7.15.   Governing Law.  This Agreement shall be governed by, and
construed in accordance with, the internal laws of the State of New York
applicable to contracts executed and fully performed within the State of New
York.

     Section 7.16.   Counterparts.  This Agreement may be executed in one or
more counterparts, and by the different parties hereto in separate counterparts,
each of which when executed shall be deemed to be an original but all of which
taken together shall constitute one and the same agreement.

                                      -42-
<PAGE>

                     [This space intentionally left blank.]

                                      -43-
<PAGE>
                                            [Preferred Stock Purchase Agreement]

     IN WITNESS WHEREOF, the Company and the Purchasers have caused this
Preferred Stock Purchase Agreement to be executed as of the date first above
written by their respective officers thereunto duly authorized.



The Company:  ADVANCED RADIO TELECOM CORP.


                              By: /s/ Henry C. Hirsch
                                  ---------------------------------------
                                  Name: Henry C. Hirsch
                                  Title:   Chairman and CEO


The Purchasers:               U.S. TELESOURCE, INC.

                              By: /s/  Marc B. Weisberg
                                  ---------------------------------------
                                  Name:  Marc B. Weisberg
                                  Title:


                              OAK INVESTMENT PARTNERS VIII, LIMITED PARTNERSHIP

                              By:  Oak Associates VIII, LLC, General Partner

                              /s/  Bandel L. Carano
                              -------------------------------------------
                              By:  Bandel L. Carano, Managing Member


                              OAK VIII AFFILIATE FUND, LIMITED PARTNERSHIP

                              By:  Oak VIII Affiliates, LLC, General Partner

                              /s/  Bandel L. Carano
                              -------------------------------------------
                              By:  Bandel L. Carano, Managing Member


                                      -44-
<PAGE>

                                            [Preferred Stock Purchase Agreement]


                              MERITECH CAPITAL PARTNERS

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

                                      -45-
<PAGE>

                                            [Preferred Stock Purchase Agreement]

                           ACCEL VI L.P.
                           BY:  ACCEL VI ASSOCIATES L.L.C.
                           ITS GENERAL PARTNER

                           By:  /s/ G. Carter Sednaoui
                                ---------------------------------
                                Managing Member


                           ACCEL INTERNET FUND II L.P.
                           BY:  ACCEL INTERNET FUND II ASSOCIATES L.L.C.
                           ITS GENERAL PARTNER

                           By:  /s/ G. Carter Sednaoui
                                ---------------------------------
                                Managing Member


                           ACCEL KEIRETSU VI L.P.
                           By:  ACCEL DEIRETSU VI ASSOCIATES L.L.C.
                           ITS GENERAL PARTNER

                           By:  /s/ G. Carter Sednaoui
                                ---------------------------------
                                Managing Member


                           ACCEL INVESTORS '98 L.P.

                           By:  /s/ G. Carter Sednaoui
                                ----------------------------------
                                General Partner

                                      -46-
<PAGE>

                                            [Preferred Stock Purchase Agreement]


                           BRENTWOOD ASSOCIATES IX, L.P.
                           By Brentwood IX Ventures, L.L.C.
                           Its General Partners

                           By:  /s/ John L. Walecka
                                ----------------------------------
                                Name:  John L. Walecka
                                Title: Managing Member


                           BRENTWOOD AFFILIATES FUND III, L.P.
                           By Brentwood IX Ventures, L.L.C.
                           Its General Partner

                           By:  /s/ John L. Walecka
                                ----------------------------------
                                Name:  John L. Walecka
                                Title: Managing Member

                                      -47-
<PAGE>

                                            [Preferred Stock Purchase Agreement]


                              COLUMBIA CAPITAL ARTT INVESTORS, LLC
                              By:  Columbia Capital, L.L.C.
                              Its:  Managing Member


                              By: /s/ James B. Fleming, Jr.
                                  -----------------------------------
                                  Name:  James B. Fleming, Jr.
                                  Title: Managing Director


                              COLUMBIA CAPITAL ARTT PARTNERS, LLC
                              By:  Columbia Capital, L.L.C.
                              Its:  Managing Member


                              By:  /s/ James B. Fleming, Jr.
                                   ---------------------------------
                                  Name:  James B. Fleming, Jr.
                                  Title: Managing Director

                                      -48-
<PAGE>

                                            [Preferred Stock Purchase Agreement]

                    WORLDVIEW TECHNOLOGY PARTNERS II, L.P.
                    By: Worldview Capital II, L.P., General Partner
                    By: Worldview Equity I, L.L.C., General Partner

                    By: /s/ James Wei
                        ---------------------------------------------
                        Name:  James Wei
                        Title:  Member

                    WORLDVIEW TECHNOLOGY INTERNATIONAL II, L.P.
                    By: Worldview Capital II, L.P., General Partner
                    By: Worldview Equity I, L.L.C., General Partner

                    By: /s/ James Wei
                        --------------------------------------------
                        Name:  James Wei
                        Title:  Member

                    WORLDVIEW STRATEGIC PARTNERS II, L.P.
                    By: Worldview Capital II, L.P., General Partner
                    By: Worldview Equity I, L.L.C., General Partner

                    By: /s/ James Wei
                        --------------------------------------------
                        Name:  James Wei
                        Title:  Member

                                      -49-
<PAGE>

                                            [Preferred Stock Purchase Agreement]

                    GLOBAL PRIVATE EQUITY II - EUROPE LIMITED PARTNERSHIP

                    GLOBAL PRIVATE EQUITY II - PGGM LIMITED PARTNERSHIP

                    DIGITAL MEDIA AND COMMUNICATIONS II LIMITED PARTNERSHIP

                    OAKSTONE VENTURES LIMITED PARTNERSHIP

                    ADVENT CROWN FUND II C.V.

                    ADWEST LIMITED PARTNERSHIP
                    By:  Advent International Limited Partnership,
                         General Partner
                    By:  Advent International Corporation,
                         General Partner
                    By:  Andrew Fillat, Senior Vice President*

                    ADVENT GLOBAL GECC LIMITED PARTNERSHIP
                    By:  Advent Global Management Limited Partnership,
                         General Partner
                    By:  Advent International Limited Partnership,
                         General Partner
                    By:  Advent International Corporation, General Partner
                    By:  Andrew Fillat, Senior Vice President*

                    ADVENT PARTNERS LIMITED PARTNERSHIP
                    By:  Advent International Corporation, General Partner
                    By:  Andrew Fillat, Senior Vice President*

                    *For all of the above:

                    /s/ Andrew Fillat
                    ----------------------------------------------------------
                    Andrew Fillat, Senior Vice President

                                      -50-
<PAGE>

                                            [Preferred Stock Purchase Agreement]

                              BESSEMER VENTURE PARTNERS IV L.P.
                              By:  Deer IV & Co. LLC, General Partner

                              By: /s/ Robert H. Buescher
                                  ---------------------------------------
                                  Name:  Robert H. Buescher
                                  Title:  Manager

                              BESSEC VENTURES IV L.P.
                              By:  Deer IV & Co. LLC, General Partner

                              By: /s/ Robert H. Buescher
                                  --------------------------------------
                                  Name:  Robert H. Buescher
                                  Title:  Manager

                              COVE VENTURES, LLC
                              By: Cove Road Associates, LLC, Managing Member

                              By: /s/ Robert Goodman
                                  --------------------------------------
                                  Name:  Robert Goodman
                                  Title:  Managing Member



                                      -51-
<PAGE>

                                            [Preferred Stock Purchase Agreement]

                              ADAMS CAPITAL MANAGEMENT, L.P.
                              By: ACM Capital Partners II, L.P., General Partner
                              By: Joel P. Adams, General Partner

                              By: /s/ Joel P. Adams
                                  ---------------------------------------
                                  Name:  Joel P. Adams
                                  Title:  General Partner

                                      -52-
<PAGE>

                                   SCHEDULE I


<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
U.S. Telesource, Inc.        945,146       179,854       358,565         N/A             $17,928,287    N/A            $90,000,000
555 17th Street
State of Residence:
Denver, CO  80202
-----------------------------------------------------------------------------------------------------------------------------------
Oak Investment Partners      412,084       78,416        156,335         46,872.00       $7,816,733     $2,343,568     $39,240,000
 VIII, Limited Partnership
525 University Avenue
Suite 1300
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Oak VIII Affiliate Fund,     7,981         1,519         3,028           N/A             $151,394       N/A            $760,000
 Limited Partnership
525 University Avenue
Suite 1300
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
MeriTech Capital Partners    262,541       49,959        99,602          N/A             $4,980,080     N/A            $25,000,000
[address]
State of Residence:
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -53-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Accel VI L.P.                128,225       24,400        48,645          14,307          $2,432,271     $715,373       $12,210,000
c/o Accel Partners
428 University Avenue
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Accel Internet Fund II L.P.  16,383        3,117         6,215           1,828           $310,757       $91,399        $1,560,000
c/o Accel Partners
428 University Avenue
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Accel Keiretsu VI L.P.       2,048         390           777             228             $38,845        $11,425        $195,000
c/o Accel Partners
428 University Avenue
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Accel Investors '98 L.P.     10,869        2,068         4,124           1,213           $206,175       $60,640        $1,035,000
428 University Avenue
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -54-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Brentwood Associates         152,799       29,076        57,968          17,576          $2,898,406     $878,837       $14,550,000
  IX, L.P.
3000 Sand Hill Road,
 Bldg. 1, Suite 260
Menlo Park, CA 94025
State of Residence:
California
-----------------------------------------------------------------------------------------------------------------------------------
Brentwood Affiliates Fund    4,726         899           1,793           N/A             $89,641        N/A            $450,000
 III, L.P.
3000 Sand Hill Road,
 Bldg. 1, Suite 260
Menlo Park, CA 94025
State of Residence:
California
-----------------------------------------------------------------------------------------------------------------------------------
Columbia ARTT Investors,     105,016       19,984        39,841          N/A             $1,992,032     N/A            $10,000,000
 LLC a Virginia LLC
-----------------------------------------------------------------------------------------------------------------------------------
Columbia ARTT Partners,      105,016       19,984        39,841          N/A             $1,992,032     N/A            $10,000,000
 LLC a Virginia LLC
201 North Union Street,
 Suite 300
State of Residence:
Alexandria
VA  22314-2642
703/519-3581
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -55-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Worldview Technology         116,808       22,228        44,314          17,577.00       $2,215,713     $878,837       $11,122,881
 Partners II, L.P.
435 Tasso, Suite 120
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Worldview Technology         35,758        6,804         13,566          N/A             $678,280       N/A            $3,404,964
 International II, L.P.
435 Tasso, Suite 120
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Worldview Strategic          4,958         944           1,881           N/A             $94,055        N/A            $472,155
 Partners II, L.P.
435 Tasso
Palo Alto, CA  94301
State of Residence:
 California
-----------------------------------------------------------------------------------------------------------------------------------
Global Private Equity II-    10,502        1,998         3,984           N/A             $199,203       N/A            $1,000,000
  Europe Limited
  Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -56-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Global Private Equity II-    26,254        4,996         9,960           N/A             $ 498,008      N/A            $2,500,000
  PGGM Limited Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Digital Media and            22,684        4,316         8,606           N/A             $ 430,279      N/A            $2,160,000
 Communications II Limited
 Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Oakstone Ventures Limited    16,204        3,083         6,147           N/A             $307,371       N/A            $1,543,000
 Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Advent Crown Fund II C.V.    16,204        3,083         6,147           N/A             $307,371       N/A            $1,543,000
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence:
 Netherlands
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -57-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Adwest Limited Partnership   4,201         799           1,594           N/A             $79,681        N/A            $400,000
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Advent Global GECC Limited   105,016       19,984        39,841          N/A             $1,992,032     N/A            $10,000,000
 Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Advent Partners Limited      8,968         1,707         3,402           N/A             $170,120       N/A            $854,000
 Partnership
c/o Advent International
75 State Street
Boston, MA  02109
State of Residence: Delaware
-----------------------------------------------------------------------------------------------------------------------------------
Bessemer Venture             31,505        5,995         11,952          N/A             $597,610       N/A            $3,000,000
 Partners IV L.P.
1400 Old Country Road,
 Suite 407
Westbury, NY  11590
Attn:  Robert H. Buescher
State of Residence:  New York
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      -58-
<PAGE>

<TABLE>
<CAPTION>
===================================================================================================================================
                                                                         MERITECH
                                                         WARRANTS        WARRANTS                       MERITECH
                            SERIES A      SERIES B      EXERCISABLE     EXERCISABLE                    PORTION OF
                            PREFERRED     PREFERRED       FOR # OF        FOR # OF        BRIDGE        BRIDGE          TOTAL
PURCHASERS AND STATES OF    STOCK # OF    STOCK # OF     SHARES OF       SHARES OF         LOAN          LOAN         PURCHASE
RESIDENCE                     SHARES        SHARES      COMMON STOCK    COMMON STOCK    COMMITMENT     COMMITMENT       PRICE
-----------------------------------------------------------------------------------------------------------------------------------
<S>                         <C>           <C>           <C>             <C>             <C>           <C>            <C>
Bessec Ventures IV, L.P.     21,003        3,997         7,968           N/A             $398,406       N/A            $2,000,000
1400 Old Country Road,
 Suite 407
Westbury, NY  11590
Attn:  Robert H. Buescher
State of Residence:  New York
-----------------------------------------------------------------------------------------------------------------------------------
Cove Ventures, LLC           31,505        5,995         11,952          N/A             $597,610       N/A            $3,000,000
1013 Cove Road
Mamaroneck, NY  10543
Attn:  Robert Goodman
State of Residence:  New York
-----------------------------------------------------------------------------------------------------------------------------------
Adams Capital                31,505        5,995         11,952          N/A             $597,610       N/A            $3,000,000
 Management, L.P.
518 Broad Street
Sewickley, PA  15143
State of Residence:
 Pennsylvania
-----------------------------------------------------------------------------------------------------------------------------------
Total:                       2,635,908     501,592       1,000,000       99,601.00       $50,000,000    $4,980,079     $251,000,000
===================================================================================================================================
</TABLE>

Basic Assumptions:

1.  Current Outstanding         =   27,200,699
2.  Preferred (as converted)    =   31,375,000
                                    ----------
3.  Total Shares Post-deal          58,575,699
4.  45% of Total                =   26,359,065
5.  Series A Total Shares       =   26,359,065/10 = 2,635,907
    Series B Total Shares       =   5,015,935     =   501,593
6.  Series B Percent of
    Total Purchase Shares       =   15.987%
7.  Series A Percent            =   84.013%
    Total Purchased Shares

To calculate Series A Shares for a fund: ($Purchase Price/$80) x .84013

To calculate Series B Shares for a fund: ($Purchase Price/$80) x .15987

                                      -59-
<PAGE>

                                  SCHEDULE II

                           Wire Transfer Instructions

US Bank
ABA  091000022

Account Name:  Phase 3 Wire Account
Account #: 173101852106

Please reference:
     Account Name:  Advanced Radio Telecom Corp.
     Account #:  41278979

     Contact:  Alex
     Phone:  206-340-8050

                                      -60-
<PAGE>

                                  SCHEDULE III

                        Schedule of Beneficial Ownership

                                      -61-